Good to see the Israelis willing to continue do business with SpaceX after all the delays with the F9 that made AMOS-4 jumping ship to the Land Launch Zenit. :)
I'll write it up, although I did have five seconds of thinking "Bloody hell, I wish we made money like space.com" ;DNot the same as making money, but I almost never go to Space.com since finding this site. :)
Good to see the Israelis willing to continue do business with SpaceX after all the delays with the F9 that made AMOS-4 jumping ship to the Land Launch Zenit. :)
What confuses me is that Amos-6 weighs 5.5ton/12,125lbs according to SFN report, far beyond Falcon 9 GTO capability(4.85 ton/10,682lbs as described by SpX's F9 page). Or did I miss something?
No, I don't think you did miss anything, but SpaceX is in the process of updating their line (to v1.1) and, as far as I recall, stats have not been announced for it yet, and 2015 is another 2 years away to boot.
Now all SpaceX has to do is up the launch rate. A lot.Definitely. Did they launch anything that was not ISS related in 2012?
Yep, same here, although I do help Anatoly Zak with his site, but he is really low on funding now so he had to make only an articles abstract publicly available and one now has to pay for the full article. May involve everything if site funding continues to decline. Hard times lay ahead for his site.I'll write it up, although I did have five seconds of thinking "Bloody hell, I wish we made money like space.com" ;DNot the same as making money, but I almost never go to Space.com since finding this site. :)
What confuses me is that Amos-6 weighs 5.5ton/12,125lbs according to SFN report, far beyond Falcon 9 GTO capability(4.85 ton/10,682lbs as described by SpX's F9 page). Or did I miss something?No, I don't think you did miss anything, but SpaceX is in the process of updating their line (to v1.1) and, as far as I recall, stats have not been announced for it yet, and 2015 is another 2 years away to boot.
The published NASA NLS F9 v1.1 performance data (http://elvperf.ksc.nasa.gov/elvMap/elvMap.ui.PerfGraph0?ReqType=Graph&OrbitType=C3&Contract=2&Vehicles=4) does suggest v1.1 is short of putting 5.5tons into GTO. Maybe that's without a "delta-v mission kit" (http://forum.nasaspaceflight.com/index.php?topic=15900.msg367231#msg367231) for which we haven't yet seen details for v1.1?
edit: Now back to KSLV-1 (looking good!). Congrats all and thanks to the NSF crew for the coverage!
That's the high-energy orbit graph, wouldn't the elliptical graph be more appropriate for GTO? Punching in an 36km x 27.0 degree elliptical (Not sure if that's standard for GTO, but closest I can find in a couple minutes of searching), the same tool gives a payload of 5715mt. Does that leave enough margin for a kick motor?Yes, you're right (doh!); elliptical with standard GTO appogee plot...
That's the high-energy orbit graph, wouldn't the elliptical graph be more appropriate for GTO? Punching in an 36km x 27.0 degree elliptical (Not sure if that's standard for GTO, but closest I can find in a couple minutes of searching), the same tool gives a payload of 5715mt. Does that leave enough margin for a kick motor?Yes, you're right (doh!); elliptical with standard GTO appogee plot...
Ex-Im Bank Approves $105.4 Million Loan to Finance SpaceX Launch
Washington, D.C. – Continuing its support of the space industry in America, the Export-Import Bank of the United States (Ex-Im Bank) has authorized a $105.4 million loan to Space Communication Ltd. of Ramat Gan, Israel, to finance the Space Exploration Technologies (SpaceX) launch of the Amos-6 communications satellite, the purchase of American made-solar arrays, and insurance brokered by Marsh USA (Marsh)
The transaction is Ex-Im Bank’s third in support of a SpaceX launch, and it will support approximately 600 U.S. jobs in California and elsewhere, according to bank estimates derived from Departments of Commerce and Labor data and methodology. In June of 2013, Ex-Im Bank announced that it had approved financing for the launches of two satellites manufactured by Space Systems/Loral LLC, and in November of 2012 the Bank announced that it had approved financing for the launches of two Boeing-manufactured satellites.
“Ex-Im Bank is always ready to help the American space industry boost its international sales and export its products to important markets,” said Ex-Im Bank Chairman and President Fred P. Hochberg. “Our support of American launches and exports levels the playing field for U.S. companies and keeps highly-skilled, well-paying jobs on American soil.”
Satellite financing represents Ex-Im Bank’s most prominent stand-out sector in the Bank's newly transformed portfolio. Just three years ago, satellites accounted for only $50 million in authorizations per year. This year numbers as the third consecutive year in which Ex-Im Bank's satellite sector authorizations will have topped $1 billion.
Amos-6, a geosynchronous satellite, will replace Space Communication’s Amos-2 and cover markets in Central and Eastern Europe and the Middle East. The satellite will also provide pan-European coverage and broadband services in Europe and Africa.
The launch is scheduled for 2015.
Founded in 2002 and headquartered in Hawthorne, Calif., SpaceX designs, manufactures and launches rockets and spacecraft. It is the first private company to build, launch, and dock spacecraft at the International Space Station, a mission previously accomplished only by government space entities.
Don't forget engineering services from SpaceX...
Don't forget engineering services from SpaceX...
Yeah, that was what I meant, in that this price give us an upper bound for the actual launch cost including all of the payload specific engineering and processing costs? Subtract off whatever the insurance and solar array costs are and whatever is left is the price spaceX is charging them for the LV hardware plus all the engineering for their payload.
Launch appears pushed back to February-March 2016
http://www.globes.co.il/en/article-spacecom-to-raise-50m-1001016293 (http://www.globes.co.il/en/article-spacecom-to-raise-50m-1001016293)
give them some time. Once assembly of the SC is complete date will be much firmer.Launch appears pushed back to February-March 2016
http://www.globes.co.il/en/article-spacecom-to-raise-50m-1001016293 (http://www.globes.co.il/en/article-spacecom-to-raise-50m-1001016293)
That's weird. I read the article, which says, "The Amos 6 satellite is meant to replace the Amos 2 satellite, due to go out of service in 2016. In late February, Spacecom announced that the launch window for Amos 6 had been deferred, and that it was expected to be in February-March 2016."
But Spacecom's website for the AMOS-6 satellite still lists launch target as Q4/2015. In their media/press releases page, there's no release that mentions a change (though, there isn't one that mentions the details in the Globes article either). A google search doesn't bring up hits on any such announcement, etc. I'm not sure where the author is getting this information. Maybe it isn't public?
http://www.calcalist.co.il/markets/articles/0,7340,L-3679157,00.html
There Date: Amos 6 will be launched into space in May 2016
Space Communications announced today the launch date of the new satellite revised - out of the sky delayed by over a year. Amos 6 will replace the Amos 2 will provide, among other things broadband services in Africa, cooperation with Facebook
http://www.calcalist.co.il/markets/articles/0,7340,L-3679157,00.html
There Date: Amos 6 will be launched into space in May 2016
Space Communications announced today the launch date of the new satellite revised - out of the sky delayed by over a year. Amos 6 will replace the Amos 2 will provide, among other things broadband services in Africa, cooperation with Facebook
wikipedia says AMOS-6 is an electric propulsion satellite, so its very likely going into a sub sync orbit, and then undergo slow transition to its GEO slot....possibly even RTLS. And this could be something that is being negotiated right now.
This suggests this launch will still be able to do ASDS landing attempt.
wikipedia says AMOS-6 is an electric propulsion satellite, so its very likely going into a sub sync orbit, and then undergo slow transition to its GEO slot.
This suggests this launch will still be able to do ASDS landing attempt.
wikipedia says AMOS-6 is an electric propulsion satellite, so its very likely going into a sub sync orbit, and then undergo slow transition to its GEO slot.
This suggests this launch will still be able to do ASDS landing attempt.
Is a low thrust engine actually more appropriate for a sub synchronous orbit than a higher thrust engine?
Is a low thrust engine actually more appropriate for a sub synchronous orbit than a higher thrust engine?
It's not about thrust, but about ISP.
Chemical propulsion satellites (aka regular) use hydrazine which sucks at ISP. You just can't drop a regular GEO bird on LEO and hope it will raise itself to GEO. If it gets there, it will be very short of station keeping fuel.
An electric satellite uses ion thrusters, which have ISP much higher even than the best chemical propulsion solution, LH2/LOX.
The low thrust also means a long time until operating station is reached. For that reason you'd still want to launch an all electric satellite as close as possible to GEO as possible.
But this makes it possible to build a massive GEO all electric bird, say 10 tons, with far more useable mission capabilities, launch it to LEO, and do the whole LEO to GEO transition while using less propellant mass than a chemical satellite would from GTO-1500m/s to GEO (actually far less).
Does this make sense ? Not rocket scientist...
wikipedia says AMOS-6 is an electric propulsion satellite, so its very likely going into a sub sync orbit, and then undergo slow transition to its GEO slot.
This suggests this launch will still be able to do ASDS landing attempt.
Is a low thrust engine actually more appropriate for a sub synchronous orbit than a higher thrust engine?
It's not about thrust, but about ISP.
Chemical propulsion satellites (aka regular) use hydrazine which sucks at ISP. You just can't drop a regular GEO bird on LEO and hope it will raise itself to GEO. If it gets there, it will be very short of station keeping fuel.
An electric satellite uses ion thrusters, which have ISP much higher even than the best chemical propulsion solution, LH2/LOX.
The low thrust also means a long time until operating station is reached. For that reason you'd still want to launch an all electric satellite as close as possible to GEO as possible.
But this makes it possible to build a massive GEO all electric bird, say 10 tons, with far more useable mission capabilities, launch it to LEO, and do the whole LEO to GEO transition while using less propellant mass than a chemical satellite would from GTO-1500m/s to GEO (actually far less).
Does this make sense ? Not rocket scientist...
The big problem with this method is that it would take A Very Long TimeTM. Sure, your all-electric bird has a great Isp. But what its engines don't have is very much actual thrust, so it ends up taking "forever" to raise the orbit. This is a potential problem for 2 reasons. 1. You've lost revenue generating time to orbit raising time. Depending on a company's economic analysis, maybe this is okay. It could theoretically be made up for by lengthening the satellite's lifetime on orbit. 2. It means that the satellite also ends up spending quite a long time getting through the Van Allen radiation belts, which is not good for the hardware on the satellite.
The big problem with this method is that it would take A Very Long TimeTM. Sure, your all-electric bird has a great Isp. But what its engines don't have is very much actual thrust, so it ends up taking "forever" to raise the orbit. This is a potential problem for 2 reasons. 1. You've lost revenue generating time to orbit raising time. Depending on a company's economic analysis, maybe this is okay. It could theoretically be made up for by lengthening the satellite's lifetime on orbit. 2. It means that the satellite also ends up spending quite a long time getting through the Van Allen radiation belts, which is not good for the hardware on the satellite.
I guess Eutelsat 115 West B already made the transfer using all electric propulsion and is now operational? Edit and ABS-3A?
Here's a paper with a bunch of plots of various tradeoffs for this strategy:
http://erps.spacegrant.org/uploads/images/images/iepc_articledownload_1988-2007/2007index/IEPC-2007-287.pdf
The big problem with this method is that it would take A Very Long TimeTM. Sure, your all-electric bird has a great Isp. But what its engines don't have is very much actual thrust, so it ends up taking "forever" to raise the orbit. This is a potential problem for 2 reasons. 1. You've lost revenue generating time to orbit raising time. Depending on a company's economic analysis, maybe this is okay. It could theoretically be made up for by lengthening the satellite's lifetime on orbit. 2. It means that the satellite also ends up spending quite a long time getting through the Van Allen radiation belts, which is not good for the hardware on the satellite.
I guess Eutelsat 115 West B already made the transfer using all electric propulsion and is now operational? Edit and ABS-3A?
Here's a paper with a bunch of plots of various tradeoffs for this strategy:
http://erps.spacegrant.org/uploads/images/images/iepc_articledownload_1988-2007/2007index/IEPC-2007-287.pdf
Great link, thanks! Just as a note though, macpacheco was talking about going from LEO to GEO, not GTO to GEO. Though, I should have made clear that he already mentioned my "problem #1" in his post.
Peter B. de Selding @pbdes 6m6 minutes ago
Spacecom of Israel: We are planning for an Aug. 22 launch, on SpaceX Falcon 9, of our Amos-6 Ku-/Ka-band telecom sat for 4 deg W.
FCC has posted the latest transmitter permit application here:
https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=72213&RequestTimeout=1000
Drone ship coordinates are:
28 6 11 N
74 34 0 W
This is about 45 miles west of the JCSAT-14 coordinates, ie closer to the Cape. This is quite a change, since the SES-9, JCSAT-14, Thaicom-8, and Eutelsat/ABS ASDS positions were all within 11 miles or so of each other.
The AMOS-6 launch date has just been announced as August 22, so this permit may be for AMOS-6, which is listed as 5500 kg. That's 700 kg more than JCSAT-14, which could explain the big difference in ASDS positions.
Also, 5500 kg is probably the upper limit for stage 1 recovery on GTO missions. The SpaceX F9 "capabilities" web page gives an F9 price of $62M for payloads up to 5500 kg to GTO. And LouScheffer's calculations have deduced an upper limit in this ballpark as well.
So AMOS-6 may turn out to be another "limiting case" stage 1 recovery experiment for SpaceX.
So we really don't have any idea yet which launch this is for?
Peter B. de Selding @pbdes 20m20 minutes ago
New target date for SpaceX launch of Spacecom's Amos-6 geo telecom satellite is 3-4 Sept (was 22 Aug.)
According to Reddit (https://www.reddit.com/r/spacex/comments/4pv7jl/amos6_launch_campaign_thread/), the core is now en-route to SLC-40 after completing its full-duration test burn at McGreggor.
Hopefully the stage is on its way to the Cape after the (reported) successful full engine burn at McGregor. If the stage arrives this weekend that would be 3 weeks away from a Sept. 3/4 launch date. ~3 weeks is the recent cadence between stage arrival at the Cape and launch.
According to Reddit (https://www.reddit.com/r/spacex/comments/4pv7jl/amos6_launch_campaign_thread/), the core is now en-route to SLC-40 after completing its full-duration test burn at McGreggor.
That's just a speculation
FCC has posted the latest transmitter permit application here:
https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=current&application_seq=72213&RequestTimeout=1000
Drone ship coordinates are:
28 6 11 N
74 34 0 W
This is about 45 miles west of the JCSAT-14 coordinates, ie closer to the Cape. This is quite a change, since the SES-9, JCSAT-14, Thaicom-8, and Eutelsat/ABS ASDS positions were all within 11 miles or so of each other.
The AMOS-6 launch date has just been announced as August 22, so this permit may be for AMOS-6, which is listed as 5500 kg. That's 700 kg more than JCSAT-14, which could explain the big difference in ASDS positions.
Also, 5500 kg is probably the upper limit for stage 1 recovery on GTO missions. The SpaceX F9 "capabilities" web page gives an F9 price of $62M for payloads up to 5500 kg to GTO. And LouScheffer's calculations have deduced an upper limit in this ballpark as well.
So AMOS-6 may turn out to be another "limiting case" stage 1 recovery experiment for SpaceX.
So we really don't have any idea yet which launch this is for?
In hindsight, that must have been for JCSAT-16. That position being 45 miles west of the JCSAT-14 position might explain why JCSAT-16 came back in better condition and why they had enough propellant to do a single engine landing burn.
Now back to AMOS-6...
Is the stage still in Texas? I've yet to see any one spotting the core on the road to Florida.
The latest launches have had the 1st stage at CC 11 days before launch and we are closing in on that date for AMOS-6 now.
Toastmastern
Is the stage still in Texas? I've yet to see any one spotting the core on the road to Florida.
The latest launches have had the 1st stage at CC 11 days before launch and we are closing in on that date for AMOS-6 now.
Toastmastern
Read back a coupe days.
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1570077#msg1570077
Now, I'm pretty sureIs the stage still in Texas? I've yet to see any one spotting the core on the road to Florida.
The latest launches have had the 1st stage at CC 11 days before launch and we are closing in on that date for AMOS-6 now.
Toastmastern
Read back a coupe days.
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1570077#msg1570077
Yea I know that but I want proof that the stage is on route
Jim West
My son took a video of a rocket leaving McGregor. He put on fb but I can't figure how to move it to this group.
Is the stage still in Texas? I've yet to see any one spotting the core on the road to Florida.
The latest launches have had the 1st stage at CC 11 days before launch and we are closing in on that date for AMOS-6 now.
Toastmastern
Read back a coupe days.
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1570077#msg1570077
Yea I know that but I want proof that the stage is on route
Is the stage still in Texas? I've yet to see any one spotting the core on the road to Florida.
The latest launches have had the 1st stage at CC 11 days before launch and we are closing in on that date for AMOS-6 now.
Toastmastern
Read back a coupe days.
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1570077#msg1570077
Yea I know that but I want proof that the stage is on route
If you'd have read the L2 info, the proof doesn't get more solid than that.
Is the stage still in Texas? I've yet to see any one spotting the core on the road to Florida.
The latest launches have had the 1st stage at CC 11 days before launch and we are closing in on that date for AMOS-6 now.
Toastmastern
Read back a coupe days.
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1570077#msg1570077
Yea I know that but I want proof that the stage is on route
If you'd have read the L2 info, the proof doesn't get more solid than that.
I didn't ser an image of the stage on route did you?
If you'd have read the L2 info AND SEEN WHO POSTED IT, you wouldn't need a photo.
Apparently Amos booster en route to cape.
https://www.facebook.com/jerry.m.west/videos/10208691238137123/ (https://www.facebook.com/jerry.m.west/videos/10208691238137123/)
...but if successful, maybe Spacecom's new Chinese owners would prefer a domestic launch vehicle?...But if the public statements of the Chinese are to be believed, SpaceX is cheaper than anything they have.
Well there is also the ITAR issue with US or Euro manufactured Comsats being launch from China....but if successful, maybe Spacecom's new Chinese owners would prefer a domestic launch vehicle?...But if the public statements of the Chinese are to be believed, SpaceX is cheaper than anything they have.
Well there is also the ITAR issue with US or Euro manufactured Comsats being launch from China....but if successful, maybe Spacecom's new Chinese owners would prefer a domestic launch vehicle?...But if the public statements of the Chinese are to be believed, SpaceX is cheaper than anything they have.
From one of the articles above, it must remain Israeli run, regardless of ownership. That may be false cover, but it's something.Well there is also the ITAR issue with US or Euro manufactured Comsats being launch from China....but if successful, maybe Spacecom's new Chinese owners would prefer a domestic launch vehicle?...But if the public statements of the Chinese are to be believed, SpaceX is cheaper than anything they have.
If the Chinese own the factory, what technology will remain to protect?
Well there is also the ITAR issue with US or Euro manufactured Comsats being launch from China....but if successful, maybe Spacecom's new Chinese owners would prefer a domestic launch vehicle?...But if the public statements of the Chinese are to be believed, SpaceX is cheaper than anything they have.
If the Chinese own the factory, what technology will remain to protect?
If the Chinese own the factory, what technology will remain to protect?
If the Chinese own the factory, what technology will remain to protect?
SpaceCom is not the factory, just the operator. Amos-6 is built in Israel Aircraft Industries, which, to the best of my knowledge, is not for sale.
There is a 60% chance of rain on Sept 1st. Do you guys think there might be a delay in launch?
I thought the launch was planned for the 3rd.I've never seen rain itself listed in an LCC, but LCC typically include a lot of things that come along with rain. From Wikipedia (https://en.wikipedia.org/wiki/Launch_commit_criteria#Falcon_9):
Speaking of which, is rain actually a problem for launches? I thought the usual weather scrubs were for high-altitude wind. Is there any reason that rain would be a problem for a Falcon 9 FT?
NASA has identified the Falcon 9 vehicle can not be launched under the following conditions. Some can be overridden if additional requirements are met.
* sustained wind at the 162 feet (49 m) level of the launch pad in excess of 30 knots (56 km/h; 35 mph)
* upper-level conditions containing wind shear[quantify] that could lead to control problems for the launch vehicle.
* launch through a cloud layer greater than 4,500 feet (1,400 m) thick that extends into freezing temperatures
* launch within 19 kilometres (10 nmi) of cumulus clouds with tops that extend into freezing temperatures,
within 19 kilometres (10 nmi) of the edge of a thunderstorm that is producing lightning within 30 minutes after the last lightning is observed.
* within 19 kilometres (10 nmi) of an attached thunderstorm anvil cloud
* within 9.3 kilometres (5 nmi) of disturbed weather clouds that extend into freezing temperatures
* within 5.6 kilometres (3 nmi) of a thunderstorm debris cloud,
through cumulus clouds formed as the result of or directly attached to a smoke plume,
The following should delay launch:
* delay launch for 15 minutes if field mill instrument readings within 9.3 kilometres (5 nmi) of the launch pad exceed +/- 1,500 volts per meter, or +/- 1,000 volts per meter
* delay launch for 30 minutes after lightning is observed within 10 nautical miles (19 km; 12 mi) of the launch pad or the flight path
From the update thread:
Interesting that the Air Force still classifies F9 flights as "expendable".
When has one been reused?That doesn't really matter, even if it gets reused even as a building ornament it can hardly be called "expendable". Also seems a bit dated given SES-10 is confirmed as launching on one this year.
And what happens with the second stage or fairing?Do they classify airplanes with a drop tank as "expendable"?
From the update thread:
Interesting that the Air Force still classifies F9 flights as "expendable".
When has one been reused? And what happens with the second stage or fairing?
Do they classify airplanes with a drop tank as "expendable"?
Anyone have a time that Elsbeth III left PC? MT.com already has her out of range of shore AIS.
But NASA didn't classify Shuttle as an expendable launch vehicle. If you go here:Do they classify airplanes with a drop tank as "expendable"?
Yeah -- under this approach at the nomenclature, the Shuttle was an expendable launch system.
I mean, what happened with the ET? ;)
That doesn't really matter, even if it gets reused even as a building ornament it can hardly be called "expendable".
I'm going to agree to disagree; I'd call it a "recoverable" launch vehicle if it is recovered but not intended for reflight as a more accurate designation than either "expendable" or "reusable". That said, the point is really moot, as SES-10 shows. And frankly, SpaceX clearly plans to recover and reuse AMOS-6's booster. If they are unable to recover and reuse the booster that might make it "expended" but not "expendable", just like an airplane crashing doesn't suddenly make that kind of airplane expendable.That doesn't really matter, even if it gets reused even as a building ornament it can hardly be called "expendable".
No, it is still an expendable launch vehicle. Retrieving parts for other uses doesn't change that
That doesn't really matter, even if it gets reused even as a building ornament it can hardly be called "expendable".
No, it is still an expendable launch vehicle. Retrieving parts for other uses doesn't change that
Please direct me elsewhere if this question has already been addressed.
What goes into a GTO launch window? This launch is happening in the absolute dead of night. For ISS rendezvous missions - I get that launch windows are completely dictated by the orbital period of the stations. For GTO launches, what constrains the launch window? If there are no orbital physics restraints, what else would push a launch to the earliest of the early morning hours? Would there be a preference on not wanting to load superchilled liquids in the heat of a florida summer day? Less likelihood of stray pleasureboats scrubbing a launch?
I would expect SpaceX to continue this 'wee hour of the morning' practice from here on out... if they can.
AMOS-6 uses electric for station keeping only. GTO transfer will be chemical.I would expect SpaceX to continue this 'wee hour of the morning' practice from here on out... if they can.
Most satellites use a combination of propellant and solar to get to their final destinations. The wee hour for this one is because the satellite is all electric, which incidentally is the weaker form of propulsion.
I can't see that any space company would prefer launches in the middle of the night, regardless of the fringe benefits. It must be a logistical nightmare to make sure all your crew is rested up to perform at their best at 3AM. You'd have to put everyone on a jet lag schedule days in advance.
However, all electric satellites can be seen as preferable for their significantly lower mass absent the mass of propellant. A more comfortable goal would likely be how to get them charged on the ground, not how to get them launched at 3AM.
Weather has nothing to do with it. The reason is for the spacecraft lighting. They want the spacecraft to be in full light after separation and during the climb to apogee. This will help ensure that the spacecraft will be power positive.
wikipedia says AMOS-6 is an electric propulsion satellite, so its very likely going into a sub sync orbit, and then undergo slow transition to its GEO slot.
This suggests this launch will still be able to do ASDS landing attempt.
Weather has nothing to do with it. The reason is for the spacecraft lighting. They want the spacecraft to be in full light after separation and during the climb to apogee. This will help ensure that the spacecraft will be power positive.
Doesn't it take weeks to get to apogee? So is it safe to assume it takes weeks to fully charge if needing electric only for stationkeeping, and that it manages to stay in the full light vector that it started in?
I said it was all electric based on the much earlier quote below, w/o having reading the article myself:wikipedia says AMOS-6 is an electric propulsion satellite, so its very likely going into a sub sync orbit, and then undergo slow transition to its GEO slot.
This suggests this launch will still be able to do ASDS landing attempt.
I would expect SpaceX to continue this 'wee hour of the morning' practice from here on out... if they can.
James Dean says only 40% go for launch at 3am on Saturday
I would expect SpaceX to continue this 'wee hour of the morning' practice from here on out... if they can.
Spacex has no real say in it. It is driven by spacecraft requirements.
I would expect SpaceX to continue this 'wee hour of the morning' practice from here on out... if they can.
Spacex has no real say in it. It is driven by spacecraft requirements.
I still don't get why they don't just charge up on the ground, if the satellite can reach apogee & sunlight in a matter of hours.
I would expect SpaceX to continue this 'wee hour of the morning' practice from here on out... if they can.
Spacex has no real say in it. It is driven by spacecraft requirements.
I still don't get why they don't just charge up on the ground, if the satellite can reach apogee & sunlight in a matter of hours.
Did anyone notice that this launch will make the US tie with Russia in number of launches this year? And surpass them later this month with non-SpaceX launches? I have no idea if there was ever a time that Russia did not dwarf all other nations in number of launches, but it's at least a decade ago, and probably before the STS. Pretty historic eh?Historic indeed. And quite sudden. For every year of the last decade, Russian launches have roughly equalled US and Chinese added together. Even as recently as 8th June this was still true; after the Proton launch that day the totals for this year were Russia 14, USA 8, China 6 (I'm getting my data from Anatoly Zak's website at
...
James Dean says only 40% go for launch at 3am on Saturday
Ouch!
So when is the next launch opportunity?
I wish they gave these odds in conditional format, as in:James Dean says only 40% go for launch at 3am on Saturday
Ouch!
So when is the next launch opportunity?
September 4 is the delay date. There's a 60% chance of weather permitting on that day.
It blew up on the pad during hot fire
It blew up on the pad during hot fire
SpaceX can confirm that in preparation for today’s static fire, there was an anomaly on the pad resulting in the loss of the vehicle and its payload. Per standard procedure, the pad was clear and there were no injuries.
I hope no one is hurt. I hope the damage to gse isn't bad. I hope there is a clear and well understood reason for whatever happened. I hope the recovery is swift.
Man this sucks.
Better to happen during test on the pad than in flight with payload loss, but still very grim news indeed.
Unless the root cause is quickly ascribed to a static fire pad test mistake and not the vehicle, that will be it for 2016 launches.
Won't be re-using that core.
I hope no one is hurt. I hope the damage to gse isn't bad. I hope there is a clear and well understood reason for whatever happened. I hope the recovery is swift.Agreed, but first and foremost hope everyone is OK.
Man this sucks.
From a friend at KSC (so this is third-hand info), incident seemed to occur at about F minus-3 minutes, so after prop load while stage was pressurizing to flight level.
From a friend at KSC (so this is third-hand info), incident seemed to occur at about F minus-3 minutes, so after prop load while stage was pressurizing to flight level.
This is a really bad failure for the Commercial Crew side of things.Wasn't it SpaceX's position that crew should board only *after* propellant load? And this is why...
This is a really bad failure for the Commercial Crew side of things.Wasn't it SpaceX's position that crew should board only *after* propellant load? And this is why...
It will also give hard data on the effectiveness of slide wire systems and shelter and such, so probably a good thing for overall crew safety, in the long run. But agreed it certainly looks bad.
Would the second stage prop have been loaded?
This is a really bad failure for the Commercial Crew side of things.Wasn't it SpaceX's position that crew should board only *after* propellant load? And this is why...
It will also give hard data on the effectiveness of slide wire systems and shelter and such, so probably a good thing for overall crew safety, in the long run. But agreed it certainly looks bad.
They're taking a firefighter out by air medivac per KSC emergency radio :'(
Is it possible that it was a problem with the loading side of things rather than the rocket itself?Would the second stage prop have been loaded?
Yes, it would also be finishing up LOX load at that point.
They're taking a firefighter out by air medivac per KSC emergency radio :'(
Sh*t :(
Also from Doug Ellison of UMSF fame, who was at the Cape today:
Doug Ellison
@doug_ellison
@NASASpaceflight I drove from CAFS to KSCVC at about 8am - looked like 1st stage only was erected.
Also from Doug Ellison of UMSF fame, who was at the Cape today:
Doug Ellison
@doug_ellison
@NASASpaceflight I drove from CAFS to KSCVC at about 8am - looked like 1st stage only was erected.
Interesting... Has there been any talk of any of the recovered cores having a test fire today?
Transporter Erector seems okay. Smoke billowing from the base of the pad. No rocket in sight.
Also from Doug Ellison of UMSF fame, who was at the Cape today:
Doug Ellison
@doug_ellison
@NASASpaceflight I drove from CAFS to KSCVC at about 8am - looked like 1st stage only was erected.
Interesting... Has there been any talk of any of the recovered cores having a test fire today?
It would have been the first two stages, not just the first stage.
Perhaps a pointless thing to say at this time, and assuming the issue has come from the rocket itself - but had this been a flight-proven Falcon 9 - would this have happened?
Is it possible that it was a problem with the loading side of things rather than the rocket itself?
They're taking a firefighter out by air medivac per KSC emergency radio :'(
Perhaps a pointless thing to say at this time, and assuming the issue has come from the rocket itself - but had this been a flight-proven Falcon 9 - would this have happened?
Very slight silver lining - might actually add more weight to using recovered stages...
Is it possible that it was a problem with the loading side of things rather than the rocket itself?
What difference does it make? It's an integrated system, one cannot function without the other. Having this failure be down to GSE doesn't make it any better.
On the flip side, this is certainly going to be an interesting data point for pad abort risk assessments, blast overpressures and the like...
Latest photos show that the T/E strongback seems intact! This is bizarre; I'm thinking that it must have been a tank top cap failure that directed most of the explosive force vertically upwards to avoid any collateral damage in that way!
Not a NASA payload==>not a NASA investigation. The SpaceX investigation need not be drawn out (unless it needs to be because the root cause is elusive). As pointed out above, it's likely that the pad reconstruction is going to take longer than the investigation.
The difference is that if it is GSE side, there would be fewer concerns relating to the rocket once it is fuelled and up in the air.
Not a NASA payload==>not a NASA investigation. The SpaceX investigation need not be drawn out (unless it needs to be because the root cause is elusive). As pointed out above, it's likely that the pad reconstruction is going to take longer than the investigation.
So could they move to LC-39 until the mess is cleaned up?
upright isn't the same as intact though. It may not be usable any more.
Unless it was a very clear case of human error. There is no idiot proofing of rockets.Not a NASA payload==>not a NASA investigation. The SpaceX investigation need not be drawn out (unless it needs to be because the root cause is elusive). As pointed out above, it's likely that the pad reconstruction is going to take longer than the investigation.
So could they move to LC-39 until the mess is cleaned up?
Cleaning up the mess may be way faster than the necessary investigation and design changes.
The difference is that if it is GSE side, there would be fewer concerns relating to the rocket once it is fuelled and up in the air.
That's not much of a consolation if you consider that the payload is up in the air on the rocket about the same length of time (30 min) as it is on the pad actively being loaded with all kinds of fluids.
upright isn't the same as intact though. It may not be usable any more.
Agreed. The discussion about the T/E likely shouldn't be about how "intact" it is, but perhaps how "salvageable".
The investigation will have to point out if there is in fact a need to change the design. Right now the cause is (publically) unknown. The cause could be something as simple as FUD in the tanks or a production fault. Those generally don't require design changes but changes to procedures.Not a NASA payload==>not a NASA investigation. The SpaceX investigation need not be drawn out (unless it needs to be because the root cause is elusive). As pointed out above, it's likely that the pad reconstruction is going to take longer than the investigation.
So could they move to LC-39 until the mess is cleaned up?
Cleaning up the mess may be way faster than the necessary investigation and design changes.
Not a NASA payload==>not a NASA investigation. The SpaceX investigation need not be drawn out (unless it needs to be because the root cause is elusive). As pointed out above, it's likely that the pad reconstruction is going to take longer than the investigation.Baseless speculation.
I am hearing that the payload was on top
I am hearing that the payload was on topAs bad as a launch failure then. Worse than most launch failures even, since some pad repair will be needed.
No pressure, but...Sigh.
"SpaceX has confirmed the loss of both the Falcon 9 rocket and its $200 million payload in today’s explosion at the launch pad."
I am hearing that the payload was on top
SpaceX confirms it was a pad issue that caused it.
This is a really bad failure for the Commercial Crew side of things.Wasn't it SpaceX's position that crew should board only *after* propellant load? And this is why...
It will also give hard data on the effectiveness of slide wire systems and shelter and such, so probably a good thing for overall crew safety, in the long run. But agreed it certainly looks bad.
One thing is almost a given now. SpaceX won't be performing static fires with the payload on top from this point forward in time.I am hearing that the payload was on top
Do they usually do the Static fire with the payload attached? are there different procedures for static fire WRT Dragon, GTO or LEO launches pertaing to payload onboard?
Wasn't the takeover of the firm who would operate AMOS-6 contingent on the successful launch of the sattelite?
Paul
If the mishap occurred at T - 3:00 as was reported earlier, that is around the time that the Flight Termination System is armed. Probably an odd coincidence, but curious, none-the-less.Isn't that also around the time that the T/E is being retracted?
Which is the point of testing the rocket engines while the P/L is on board? If there is any incident, like today's, the P/L is going to be lost anyway.
So the payload was lost as well?
Which is the point of testing the rocket engines while the P/L is on board? If there is any incident, like today's, the P/L is going to be lost anyway.
If the mishap occurred at T - 3:00 as was reported earlier, that is around the time that the Flight Termination System is armed. Probably an odd coincidence, but curious, none-the-less.Isn't that also around the time that the T/E is being retracted?
Strongback retraction begins at T-5:30.
Hm, that could definitely slow down their launch opsOne thing is almost a given now. SpaceX won't be performing static fires with the payload on top from this point forward in time.I am hearing that the payload was on top
Do they usually do the Static fire with the payload attached? are there different procedures for static fire WRT Dragon, GTO or LEO launches pertaing to payload onboard?
SpaceX confirms it was a pad issue that caused it.
Where? They said "an anomaly on the pad". Of course it was on the pad. Doesn't make it a pad issue, though.
So the payload was lost as well?
Even if it wasn't destroyed outright, it would have suffered severe enough damage to be an insurance write-off; it would be cheaper to build a new satellite than try to fix AMOS-6.Which is the point of testing the rocket engines while the P/L is on board? If there is any incident, like today's, the P/L is going to be lost anyway.
As I understand it, the engines are already flight condition verified after they are fired at McGreggor; it's more of a case to ensure all vehicle systems are ready for flight as an integrated unit (including IU control of all systems and software parameters correct). Any structural failure at CCAFS raises more questions about post-test analysis at McGreggor than anything else (IMO)
SpaceX confirms it was a pad issue that caused it.
Where? They said "an anomaly on the pad". Of course it was on the pad. Doesn't make it a pad issue, though.
Another learning opportunity and chance to improve.
It's very disappointing that there isn't enough fail safes in the GSE to avoid a loss of vehicle on the ground. That should be the easiest part of this business.
Closeup of the pad from the WFTV streamDoes not seem retracted.
Which is the point of testing the rocket engines while the P/L is on board? If there is any incident, like today's, the P/L is going to be lost anyway.If the payload is integrated then they can launch sooner once a good static fire is confirmed. Unfortunately, you also run the risk of something like this happening. :(
Is the flight termination system armed during static fires?
If the mishap occurred at T - 3:00 as was reported earlier, that is around the time that the Flight Termination System is armed. Probably an odd coincidence, but curious, none-the-less.Isn't that also around the time that the T/E is being retracted?
- Ed Kyle
Which is the point of testing the rocket engines while the P/L is on board? If there is any incident, like today's, the P/L is going to be lost anyway.If the payload is integrated then they can launch sooner once a good static fire is confirmed. Unfortunately, you also run the risk of something like this happening. :(
There is going to be a cascade of consequences stemming from the events of today. Between this and the still-recent CRS-7 failure, it effectively junks an impression that SpaceX likes to put forward - that it has the expertise and reliability necessary to go to Mars. Right now it is unable to even clear its satellite backlog.
The company is still very young, and this demonstrated lack of reliability relative to other companies/organisations underscores how far it has to go before it fulfills its undoubted potential.
Ok, so I wake up this morning, go to check the news as usual, and well this was the lasting thing I expected to see as the headline story on CNN.
Really not good for SpaceX considering last year's incident as well. If I was a customer and saw SpaceX with two fails in about a year, and ULA with over 100 successful launches in a row... Well... Umm... Really feel sorry for SpaceX though. Launch pad is gone. Time to get Pad 39a ready ASAP I guess. Devastating.
Terrible news.
At least it won't be counted as a launch failure. Or would it?
This is terrible news :'(
Could this jeapordize the company itself? SpaceX might not have a backlog problem anymore :(
I mean, forget Mars 2018 or the Falcon Heavy, I'd expect the FH by Winter of next year or the year after next if we are lucky, and Mars is still as distant a dream as ever... Am I being too pessimistic about this?
Absolutely terrible that this happened so close to Elon Musk's unveiling of his MCT and associated Mars infrastructure plans, it makes it look like a joke now :(
Yes, you are overreacting. I am sure that Spacex will take a hit, but I cannot see the failure being a threat to the existence of company. The cost advantage of Spacex is significant even with the current failure rate.
If the payload is not on the rocket for static fire it isn't anywhere near the pad. It's back at the processing building waiting for static fire to occur.
If the payload is not on the rocket for static fire it isn't anywhere near the pad. It's back at the processing building waiting for static fire to occur.
Payload was on the pad https://twitter.com/SciGuySpace/status/771352111657385984
Absolutely gutted for everyone at SpaceX. And just as they were starting to ramp up the launch rate, anouncement of the first relaunch, the imminent release of the Mars plans. Hope they pick this one up swiftly and thoruoghly.
I guess space is still hard.
If the payload is not on the rocket for static fire it isn't anywhere near the pad. It's back at the processing building waiting for static fire to occur.
Payload was on the pad https://twitter.com/SciGuySpace/status/771352111657385984
I said IF the payload wasn't on the rocket, obviously not the case here...
Arianespace had multiple failures with loss of payload yet still became the worlds leading commercial launch provider. Proton had multiple failures, with loss of payload, yet continues launching commercial and government payload. Older versions of Atlas, Delta had multiple failures with loss of payload yet continued to fly for nearly 4 decades. That goes for multiple versions of Titan as well. All of these vehicles were operated by commercial entities. None of them folded because of failures.This is terrible news :'(
Could this jeapordize the company itself? SpaceX might not have a backlog problem anymore :(
I mean, forget Mars 2018 or the Falcon Heavy, I'd expect the FH by Winter of next year or the year after next if we are lucky, and Mars is still as distant a dream as ever... Am I being too pessimistic about this?
Absolutely terrible that this happened so close to Elon Musk's unveiling of his MCT and associated Mars infrastructure plans, it makes it look like a joke now :(
No need to be overly dramatic. Certainly a major setback, but there is no indication SpaceX won't be able to recover.
Customers generally understand that space is hard. IMO SpaceX will suffer from this event, but it certainly will not endanger the continued existence of SpaceX as a company.
Terrible news.
At least it won't be counted as a launch failure. Or would it?
So what is the contingency plan for SpaceX KSC operations? How fast can they get 39 up and running for F9 if the damage at the pad will take a long time to fix?
Terrible news.
At least it won't be counted as a launch failure. Or would it?
Of course it would, and should. With the payload gone, this is a total launch campaign failure.
ok sorry, I thought you hadn't heard it yet...
Padrat, how are the SpaceX folk holding up?
ok sorry, I thought you hadn't heard it yet...
Oh trust me, I've heard.....
Hi, I'm Padrat, nice to meet you, lol (inside joke for the space vets on here)
Strongback retraction begins at T-5:30. Although I saw a CBS news tweet that said something about 5 minutes before ignition.
T-0:05:55 Pressurization for Strongback Retract
T-0:05:30 Strongback Cradles Opening
T-0:05:00 Second Stage Nitrogen Loading Termination
T-0:04:46 Stage 1 & Stage 2 Auto Sequence starts
T-0:04:30 Stage 2 Thrust Vector Control Test
T-0:04:25 Strongback Retraction
T-0:04:10 Vehicle Release Auto Sequence
T-0:03:45 Verify Good Mvac TVC
T-0:03:40 TEA-TEB Ignition System Activation
T-0:03:30 Strongback Retraction complete
T-0:03:25 Flight Termination System to Internal Power
T-0:03:05 Flight Termination System Armed
T-0:03:00 LOX Topping Termination
T-0:03:00 Strongback Securing complete
T-0:02:45 Fuel Trim Valve to Flight Position
T-0:02:40 FTS Countdown Sequence
T-0:02:30 Launch Director: Go for Launch
T-0:02:20 Propellant Tank Pre-Press
T-0:02:00 Range Verification
T-0:02:00 Flight Control to Self Alignment
T-0:01:35 Helium Loading Termination
T-0:01:30 Final Engine Chilldown, Pre-Valves/Bleeders Open
T-0:01:20 Engine Purge
T-0:01:00 Flight Computer to start-up
T-0:01:00 Pad Deck Water Deluge System Activation
T-0:00:55 Second Stage to Flight Pressure
T-0:00:50 First Stage Thrust Vector Actuator Test
T-0:00:40 First Stage to Flight Pressure
T-0:00:20 All Tanks at Flight Pressure
T-0:00:15 Arm Pyrotechnics
T-0:00:10 Latest VC Abort
T-0:00:03 Merlin Engine Ignition
T-0:00:00 LIFTOFF
there was an earlier post of the countdown events going back to about T-5 min. I was wondering if anyone has the events for the 5 minutes before that - so from T-10 or so on? Fine if its for launch countdown vs. static fire, it should be close enough.
Arianespace had multiple failures with loss of payload yet still became the worlds leading commercial launch provider. Proton had multiple failures, with loss of payload, yet continues launching commercial and government payload. Older versions of Atlas, Delta had multiple failures with loss of payload yet continued to fly for nearly 4 decades. That goes for multiple versions of Titan as well. All of these vehicles were operated by commercial entities. None of them folded because of failures.This is terrible news :'(
Could this jeapordize the company itself? SpaceX might not have a backlog problem anymore :(
I mean, forget Mars 2018 or the Falcon Heavy, I'd expect the FH by Winter of next year or the year after next if we are lucky, and Mars is still as distant a dream as ever... Am I being too pessimistic about this?
Absolutely terrible that this happened so close to Elon Musk's unveiling of his MCT and associated Mars infrastructure plans, it makes it look like a joke now :(
No need to be overly dramatic. Certainly a major setback, but there is no indication SpaceX won't be able to recover.
Customers generally understand that space is hard. IMO SpaceX will suffer from this event, but it certainly will not endanger the continued existence of SpaceX as a company.
In at least one way, this is worse than a launch failure, since that type of failure may leave the pad intact.
I'm really sad about this. I hope they don't lose too many backlogged customers during the recovery period.
when they do a static fire do they fully fuel the rocket or is it mostly empty?Test as you fly. It was a full rocket.
do we have an estimate of % full?
Depending on the extent of damage to the pad, could they use this as an opportunity to upgrade LC-40 for Falcon Heavy?
In at least one way, this is worse than a launch failure, since that type of failure may leave the pad intact.
I'm really sad about this. I hope they don't lose too many backlogged customers during the recovery period.
It's hard to say at this point but, in terms of pad damage, it doesn't look as bad as the Antares failure.
It's a rough day for us mere "fans", I can't imagine what it's like for you folks. Here's hoping for a quick fault determination, resolution and return to flight.
ok sorry, I thought you hadn't heard it yet...
Oh trust me, I've heard.....
Hi, I'm Padrat, nice to meet you, lol (inside joke for the space vets on here)
Padrat, how are the SpaceX folk holding up?
AIUI, this happened before ignition, so following assumes that.
So bearing in mind the engines were not running, what can cause an explosion? Presumably since the fire was almost about to go ahead, the rocket was fully loaded with propellant, loading complete. What was going on that could actually cause the issue?
AIUI, this happened before ignition, so following assumes that.
So bearing in mind the engines were not running, what can cause an explosion? Presumably since the fire was almost about to go ahead, the rocket was fully loaded with propellant, loading complete. What was going on that could actually cause the issue?
Has there even been an accidental FTS firing? (Not saying that's what this was, just asking).
What was going on that could actually cause the issue?
another COPV?
So bearing in mind the engines were not running, what can cause an explosion?
another COPV?
It is noteworthy that the issue appears to have been with the pad and ground systems, considering the small statement given by SpaceX,
To add more words to Jim's answer. LC-40 as built for Titan had two holes for the Titan III SRM flame trench. The Titan core was airlit in flight and did not need or have a flame trench. The Falcon 9 only uses one of those holes. To convert LC-40 for Falcon Heavy a large amount of concrete needs to be removed to add a flame trench for the center core. So to quote Jim not feasible in a way that is cost effective.Depending on the extent of damage to the pad, could they use this as an opportunity to upgrade LC-40 for Falcon Heavy?Not feasible
It is noteworthy that the issue appears to have been with the pad and ground systems, considering the small statement given by SpaceX, and not the rocket.
another COPV?
That's what I'm thinking.
It is noteworthy that the issue appears to have been with the pad and ground systems, considering the small statement given by SpaceX,
The Spacex statement says nothing of the sort.
I just got out of a meeting, during which my boss looked at his phone and said "A SpaceX rocket just exploded" and I got a big lump in my throat. My thoughts immediately went to the engines, that it had been an engine failure during the static fire itself.
So I'm actually heartened to hear the reports that the failure occurred before ignition and was (likely?) due to the pad hardware side. That immediately takes out a lot of variables. For the moment, it seems that the basic design of the F9 is still sound.
It is noteworthy that the issue appears to have been with the pad and ground systems, considering the small statement given by SpaceX,
The Spacex statement says nothing of the sort.
Agreed. People are running with the reported statement of an "anomaly on the pad" to vindicate the F9 itself and point at the GSE. The reality is we have no idea what happened - only SpaceX has the first clues to root cause yet, and they obviously won't say much very soon, unless Elon gets bored this weekend on Twitter.
Payload contained Hydrazine, also hypergolic, so if something started up there it could have lead to the rest of the vehicle going with it.
only SpaceX has the first clues to root cause yet, and they obviously won't say much very soon, unless Elon gets bored this weekend on Twitter.
there was an earlier post of the countdown events going back to about T-5 min. I was wondering if anyone has the events for the 5 minutes before that - so from T-10 or so on? Fine if its for launch countdown vs. static fire, it should be close enough.
Per the JCSAT-16 timeline, at T-7 engine chill down should have started.
Source for the timeline is: http://spaceflight101.com/falcon-9-countdown-timeline/ I haven't been able to find other sources with this level of detail, but most of the major events seem to line up with this one.
I did see that this timeline applies to Falcon 9 V1.0 (missed that, earlier), so I'm guessing some of the events will have been shifted to accommodate the different fueling requirements. Does any one have a more current countdown timeline?
The entire timeline I found is:
Time Event
L-10:00:00 Falcon 9 to Vertical
L-8:30:00 Countdown Initiation, Launch Vehicle Power-Up
L-6:00:00 First Weather Balloon Release
L-5:00:00 Launch Area Evacuation
L-4:45:00 Range Controllers on Station
L-4:35:00 Falcon 9 Attitude Control System N2 Loading
L-4:50:00 Falcon 9 Reconfiguration for Propellant Loading
L-4:37:00 GO for Propellant Loading
L-4:20:00 Rocket Propellant 1 Loading
L-4:00:00 Eastern Range Countdown Initiation
L-4:00:00 LOX Systems Setup & Chilldown Ops
L-3:45:00 LOX Loading
L-2:45:00 Falcon 9 RF & Telemetry Checks
L-2:30:00 Falcon 9 Launch Vehicle Release System Test
L-2:25:00 TEA-TEB Bleed In
L-2:00:00 RP-1 Tanking complete
L-1:45:00 Comm & FTS Checks
L-1:40:00 Data Flow Tests with Downrange Tracking Stations
L-1:30:00 LOX Replenish
L-1:00:00 Weather Briefing
L-0:50:00 RF Link Checks
L-0:45:00 Flight Control System Setup (Flight Software Loading)
L-0:30:00 Final LOX Topping
L-0:27:00 Spacecraft to Internal Power
L-0:13:00 COUNTDOWN HOLD POINT
L-0:13:00 Launch Director Poll
L-0:11:00 Terminal Count Briefing
T-0:10:00 Terminal Countdown
T-0:09:55 Verify that Terminal Countdown has started
T-0:09:50 Range Recorders Start
T-0:09:45 Launch Enable to Flight Mode
T-0:09:30 First Stage Merlin Engine Chilldown, Pre Valves to Open
T-0:09:20 Ground TEA-TEB Setup
T-0:09:17 Merlin 1D: Lox Bleeder Valves Open
T-0:08:15 Engine Trim Valve Cycling
T-0:07:30 Go/No Go for Launch
T-0:07:00 Spacecraft on Internal Power
T-0:07:00 First Stage Heater Shutdown
T-0:07:00 First Stage ACS Close-Out
T-0:06:35 Second Stage Heater Shutdown
T-0:06:25 Falcon 9 to Internal Power
T-0:06:00 Transfer to Internal complete
T-0:05:55 Pressurization for Strongback Retract
T-0:05:30 Strongback Cradles Opening
T-0:05:00 Second Stage Nitrogen Loading Termination
T-0:04:46 Stage 1 & Stage 2 Auto Sequence starts
T-0:04:30 Stage 2 Thrust Vector Control Test
T-0:04:25 Strongback Retraction
T-0:04:10 Vehicle Release Auto Sequence
T-0:03:45 Verify Good Mvac TVC
T-0:03:40 TEA-TEB Ignition System Activation
T-0:03:30 Strongback Retraction complete
T-0:03:25 Flight Termination System to Internal Power
T-0:03:05 Flight Termination System Armed
T-0:03:00 LOX Topping Termination
T-0:03:00 Strongback Securing complete
T-0:02:45 Fuel Trim Valve to Flight Position
T-0:02:40 FTS Countdown Sequence
T-0:02:30 Launch Director: Go for Launch
T-0:02:20 Propellant Tank Pre-Press
T-0:02:00 Range Verification
T-0:02:00 Flight Control to Self Alignment
T-0:01:35 Helium Loading Termination
T-0:01:30 Final Engine Chilldown, Pre-Valves/Bleeders Open
T-0:01:20 Engine Purge
T-0:01:00 Flight Computer to start-up
T-0:01:00 Pad Deck Water Deluge System Activation
T-0:00:55 Second Stage to Flight Pressure
T-0:00:50 First Stage Thrust Vector Actuator Test
T-0:00:40 First Stage to Flight Pressure
T-0:00:20 All Tanks at Flight Pressure
T-0:00:15 Arm Pyrotechnics
T-0:00:10 Latest VC Abort
T-0:00:03 Merlin Engine Ignition
T-0:00:00 LIFTOFF
At this stage we can at most bound the consequences.True.
Worst case: root cause is hard to determine, causing a lengthy investigation. Results reveal changes needed to some fundamental part of the rocket, including those already manufactured, followed by significant re-testing. (As in the Space Shuttle disasters). Could result in a 2 year delay..I strongly doubt SX would cease launches for 2 years.
It is noteworthy that the issue appears to have been with the pad and ground systems, considering the small statement given by SpaceX,
The Spacex statement says nothing of the sort.
Agreed. People are running with the reported statement of an "anomaly on the pad" to vindicate the F9 itself and point at the GSE. The reality is we have no idea what happened - only SpaceX has the first clues to root cause yet, and they obviously won't say much very soon, unless Elon gets bored this weekend on Twitter.
In all fairness, the first one to come up with that misinterpretation on this thread was Jim himself, IIRC :)
Can we say with confidence that it wasn't an engine problem, since it hadn't started them yet?
Pad is said to have survived well in terms of damage. Charring is heavy but but SLC-40 did not suffer like MARS SLC-0A as that was an above pad explosion. where as the SLC-40 explosion saw flames shooting out the flame trench as well as upwards. Antares explosion was downwards and falling debris.
Bummer--my thoughts with SpX and the spaceflight community.
Having said that, and in keeping with my career at a project manager, a couple thoughts:
Based on the MARS experience, it would appear SLC40 will be out of commission for quite some time (a year?). This would indicate ramping up pad 39A completion to get back to launch capability asap. However, as padrat and others would attest, the skills required to get a pad flight ready are somewhat specialized, so the conundrum: get 39A ready at the expense of repairing SLC40? If the team(s) is split, that slows down both efforts. This is a tough one for sure!
Years ago a number of us questioned (expressed concern?) the proximity of the HIF to 39A. Others dismissed such questions with variations of "Its a prefab bldg., no big deal". In light of today's events, I wonder if folks are so cavalier, especially considering the implications of having three flight ready cores in the HIF during a FH test or launch...
Payload contained Hydrazine, also hypergolic, so if something started up there it could have lead to the rest of the vehicle going with it.
Least likely. But the payload could be an ignition source if the vehicle collapsed for other reasons
another COPV?
That's what I'm thinking.
Dumb question but what is COPV?
Dumb question but what is COPV?
another COPV?
Has there even been an accidental FTS firing? (Not saying that's what this was, just asking).Yes. Happened on one of the first Titan 1 R&D missiles. There were others too, I believe, more related to incorrect tracking data that forced an RSO decision, but hasn't happened in many years since.
Has there even been an accidental FTS firing? (Not saying that's what this was, just asking).Yes. Happened on one of the first Titan 1 R&D missiles. There were others too, I believe, but hasn't happened in many years since.
- Ed Kyle
Everyone posting v1.0 or v1.1-pre-FT timelines, please stop. Consider removing your posts. It's actively unhelpful. Fuel loading procedures changed significantly for 1.1 FT with its supercooled propellants.
For that matter, we don't even know if the failure happened around T-5 or T-3 yet.
True. However SX have always been very good at learning from their past mistakes. AFAIK they never make the same mistake twice.another COPV?
Hm, now _that_ would really hurt SpaceX' reputation...
Dumb question but what is COPV?
Dumb question but what is COPV?
Photos of the pad seem to show the strong back not retracted. Can anyone tell if it looks like the cradle arms were opened? If so, that bounds the time of the incident pretty well.Well if this is anything to go by:
Caused by a GSE issue (i.e. over pressurization), or by a flaw in the vehicle systems (relief valve, strut, tank itself, etc.)?
Photos of the pad seem to show the strong back not retracted. Can anyone tell if it looks like the cradle arms were opened? If so, that bounds the time of the incident pretty well.
Photos of the pad seem to show the strong back not retracted. Can anyone tell if it looks like the cradle arms were opened? If so, that bounds the time of the incident pretty well.
Photos of the pad seem to show the strong back not retracted. Can anyone tell if it looks like the cradle arms were opened? If so, that bounds the time of the incident pretty well.
i think its possible the arms we're closed bc it looks like they were bent/pulled downward. not a for sure thing though.
Reconstructing things like the TE and other pad systems has historically (in similar events) taken a number of months described by two digits, correct?Hard to say, since the TE has been rebuilt three or so times at Vandenberg alone, then twice more I think at LC39A? The pad systems have also been a research project, what with the supercooling apparatus. The design keeps changing as the rocket evolves. If you're rebuilding an existing proven design with no changes---who knows? I don't think we have any evidence on "SpaceX time" for this task, although we have timelines from MARS etc... which is a simpler pad but perhaps more heavily damaged.
Reconstructing things like the TE and other pad systems has historically (in similar events) taken a number of months described by two digits, correct?
If it was a falcon failure, and its not possible to determine the cause from telemetry, there might be a better chance they'll recover the failed component given the failure was on the ground. (looking for a silver lining here.)
Is any better telemetry available from the falcon while its on the pad, as compared to once its in flight? Or does the rocket use radio telemetry at that point in the static fire?
Dumb question but what is COPV?
Composite overwrapped pressure vessel, holds helium for tank pressurisation. Failure of a strut / struts holding a COPV caused the loss of of CRS-7 - it broke free and ruptured the second stage LOX tank.
https://www.nasaspaceflight.com/2015/07/spacex-falcon-9-failure-investigation-focuses-update/
As noted above, this failure occurred under significant g-loadings - which would not have been a factor while the vehicle was at the pad.
the top third or fourth on the TEL has been bent towards where the rocket once stood. Its current position is not fully indicative of the the position of the TEL at the time of LoV.Photos of the pad seem to show the strong back not retracted. Can anyone tell if it looks like the cradle arms were opened? If so, that bounds the time of the incident pretty well.
i think its possible the arms we're closed bc it looks like they were bent/pulled downward. not a for sure thing though.
That was the 2nd incident.
That was the 2nd incident.
Dumb question but what is COPV?
Composite overwrapped pressure vessel, holds helium for tank pressurisation. Failure of a strut / struts holding a COPV caused the loss of of CRS-7 - it broke free and ruptured the second stage LOX tank.
https://www.nasaspaceflight.com/2015/07/spacex-falcon-9-failure-investigation-focuses-update/
As noted above, this failure occurred under significant g-loadings - which would not have been a factor while the vehicle was at the pad.
That was the 2nd incident.
So rumour is it was a pad issue, hmm.
That was the 2nd incident.
What was the first COPV indecent? I seem to have forgotten.
That was the 2nd incident.
What was the first COPV indecent? I seem to have forgotten.
Unless there was another anomaly we never publicly heard of, the original OG-1 static fire (2014?) suffered a copious He leak and subsequent LOX venting to the point of people speculating the tank ruptured.
If I remember correctly I think with the orbcomm mission there was some type of 'almost' anomaly during launch prep or static fire, saw some vague mentions, but never any details (probably details in L2)
edit - add link
Found discussion here: http://forum.nasaspaceflight.com/index.php?topic=33089.360 (http://forum.nasaspaceflight.com/index.php?topic=33089.360), Was just discussion, no idea if anything was ever confirmed, (and there is mention of perhaps something similar during SES-8)
Jim is entirely correct. The origin for this seems to have been Eric Berger's Twitter account where he read the official SpaceX statement wrong and tweeted that a pad anomaly had destroyed the F9 and the payload. The statement in fact had nothing of the sort, it was "an anomaly on the pad".So rumour is it was a pad issue, hmm.
No such rumor
Ex-employee on reddit:
No this was an issue with the pad itself, not the rocket.
It's not an assumption. Let's just say I'm connected
But can the COPV really be blamed for the strut failure? Or are you lumping in the design that includes placing the COPVs inside the propellent tank?Dumb question but what is COPV?
Composite overwrapped pressure vessel, holds helium for tank pressurisation. Failure of a strut / struts holding a COPV caused the loss of of CRS-7 - it broke free and ruptured the second stage LOX tank.
https://www.nasaspaceflight.com/2015/07/spacex-falcon-9-failure-investigation-focuses-update/
As noted above, this failure occurred under significant g-loadings - which would not have been a factor while the vehicle was at the pad.
That was the 2nd incident.
Ex-employee on reddit:
No this was an issue with the pad itself, not the rocket.
It's not an assumption. Let's just say I'm connected
Likely based on another false report that was spread earlier.
It won't take long to figure this out. I bet we know the cause in less than a week. Maybe 1-2 days.
Rockets are hard, lots of things can go wrong. This is obviously an avoidable mistake and I doubt it will be a big problem to fix. Which will make it even more embarrassing for SpaceX, but they'll recover.
If it is proven to not be a vehicle problem then production needs to go full speed ahead. Fill the hangers and get ready for RTF.
For all we know at this time, this may not have much of an impact on the VAFB launches.
I give zero cred to a supposed ex-employee being so connected that he/she knows the cause before most likely anybody in SX does
I give zero cred to a supposed ex-employee being so connected that he/she knows the cause before most likely anybody in SX does
It won't take long to figure this out. I bet we know the cause in less than a week. Maybe 1-2 days.
It won't take long to figure this out. I bet we know the cause in less than a week. Maybe 1-2 days.
Rockets are hard, lots of things can go wrong. This is obviously an avoidable mistake and I doubt it will be a big problem to fix. Which will make it even more embarrassing for SpaceX, but they'll recover.
If it is proven to not be a vehicle problem then production needs to go full speed ahead. Fill the hangers and get ready for RTF.
For all we know at this time, this may not have much of an impact on the VAFB launches.
Usually the folks at USLaunchReport have a camera(from a distance) on the static fires. Haven't posted anything yet.
Of course. This was a sudden explosion, not a pad fire. Fire alarms only look for fire not explosions.QuoteParabolicarc.com @spacecom 12m12 minutes ago California, USA
Hearing from a source that whatever went wrong happened very quickly. Windows blown in at KSC before pad fire alarm sounded #SpaceX #Falcon9
https://twitter.com/spacecom/status/771381094092410881 (https://twitter.com/spacecom/status/771381094092410881)
It won't take long to figure this out. I bet we know the cause in less than a week. Maybe 1-2 days.
That may be a bit too optimistic but I'm not expecting a huge mystery that stretches out for weeks either.
Why? I'd say most of the vehicle's remains will be found and, as the rocket was plugged into the ground data lines until destruction, there is no possibility of loss of telemetry until the actual physical destruction of the data lines or the IU instrumentation package, whichever came first, both of which would have been post-failure (if only by hundredths of seconds). So, SpaceX's engineers will already have quality-A data and that will only improve as more and more debris is brought in an analysed.
Usually the folks at USLaunchReport have a camera(from a distance) on the static fires. Haven't posted anything yet.
This might be cynical of me, but I wonder if they're shopping the video around.
highspeed cameras would have been activated around the start of the automated sequence.It won't take long to figure this out. I bet we know the cause in less than a week. Maybe 1-2 days.
That may be a bit too optimistic but I'm not expecting a huge mystery that stretches out for weeks either.
Why? I'd say most of the vehicle's remains will be found and, as the rocket was plugged into the ground data lines until destruction, there is no possibility of loss of telemetry until the actual physical destruction of the data lines or the IU instrumentation package, whichever came first, both of which would have been post-failure (if only by hundredths of seconds). So, SpaceX's engineers will already have quality-A data and that will only improve as more and more debris is brought in an analysed.
That and the pad video cameras. Even if they are only standard cameras that's 30 frames per second and with a good close up. Could easily have a higher frame rate.
If this is a pad failure then procedures are a likely culprit. Inadequate inspections, checks, etc?your statements are not valid.
If the root cause is traced to a procedural issue, that would goes a long way toward showing why rapid launch cadence is difficult to achieve. So many things have to happen in such rapid succession and in exactly the right order and with exactly the right timing, or else *BOOM*. The answer for why ULA can't launch faster than they do is not just that "old aerospace" is inefficient.
Usually the folks at USLaunchReport have a camera(from a distance) on the static fires. Haven't posted anything yet.
This might be cynical of me, but I wonder if they're shopping the video around.
Dumb question but what is COPV?
http://bfy.tw/7Us0
Photos of the pad seem to show the strong back not retracted. Can anyone tell if it looks like the cradle arms were opened? If so, that bounds the time of the incident pretty well.
i think its possible the arms we're closed bc it looks like they were bent/pulled downward. not a for sure thing though.
or possibly the rods that connect the top section of the TEL to the rest of it deformed from the heat?
including thermal infrared
..
SpaceX will have high res video stream recordings of pad camera from multiple angles,
Well, at least we know it wasn't the rocket engines. This took place before firing. I've heard there were multiple explosions?One big explosion, followed by a big fire and a series of secondary explosions. Typical of a fire where multiple pressure vessels are present.
No, this is not correct, the supposed ex-employee source on reddit denies that. They state:
I'm not exactly allowed to reveal sources. It'll still be months before things settle down, but it was definitely a pad issue.
Look it may be baloney, we can't say anything for sure, that's why it's a rumour.
If this is a pad failure then procedures are a likely culprit. Inadequate inspections, checks, etc?I see you are new. Welcome to the site.
If the root cause is traced to a procedural issue, that would goes a long way toward showing why rapid launch cadence is difficult to achieve. So many things have to happen in such rapid succession and in exactly the right order and with exactly the right timing, or else *BOOM*. The answer for why ULA can't launch faster than they do is not just that "old aerospace" is inefficient.
Well, at least we know it wasn't the rocket engines. This took place before firing. I've heard there were multiple explosions?One big explosion, followed by a big fire and a series of secondary explosions. Typical of a fire where multiple pressure vessels are present.
- Ed Kyle
Given that booster passed in McGregor.
Then transported to ksc.
Nothing happened to booster during transit.
Then the gse is the only variable.
LV related cause :( This means all flights grounded and no immediate cause found. Was hopping for a pad fault that couldn't happen at Vanderberg.
Part of me hopes that it's something that is easy to fix. But if it's easy to fix, people will ask "why wasn't it detected?".True.
The COPV would be bad news as it could imply that SpaceX is unable to fix that issue.Just to be clear IIRC it was not the COPV in the LOX tank but the struts holding them that failed and (eventually) caused the COPV's to fail.
Elon Musk @elonmusk 29s30 seconds ago
Loss of Falcon vehicle today during propellant fill operation. Originated around upper stage oxygen tank. Cause still unknown. More soon.
Elon Musk @elonmusk 29s30 seconds ago
Loss of Falcon vehicle today during propellant fill operation. Originated around upper stage oxygen tank. Cause still unknown. More soon.
Elon Musk @elonmusk 29s30 seconds ago
Loss of Falcon vehicle today during propellant fill operation. Originated around upper stage oxygen tank. Cause still unknown. More soon.
Well if there is a problem with the rocket... 2 major failures in 14 months... is going to be grounded for a while.
LV related cause :( This means all flights grounded and no immediate cause found. Was hopping for a pad fault that couldn't happen at Vanderberg.
No one said it was LV related. Elon just said "around upper stage oxygen tank". Could still be GSE.
Elon Musk @elonmusk 29s30 seconds ago
Loss of Falcon vehicle today during propellant fill operation. Originated around upper stage oxygen tank. Cause still unknown. More soon.
Forgive me if this is a stupid question, but what could cause an explosion around that tank?
Part of me hopes that it's something that is easy to fix. But if it's easy to fix, people will ask "why wasn't it detected?".True.QuoteThe COPV would be bad news as it could imply that SpaceX is unable to fix that issue.Just to be clear IIRC it was not the COPV in the LOX tank but the struts holding them that failed and (eventually) caused the COPV's to fail.
Historically COPV's have been pretty reliable components. They have (relatively) generous safety margins for space structures. They should be minimized not because of the danger but the paperwork they generate to show they've been tested and inspected. IIRC the ones on the SSME's last the life of each orbiter without replacement, roughly 30 flights each.
Elon Musk @elonmusk 29s30 seconds ago
Loss of Falcon vehicle today during propellant fill operation. Originated around upper stage oxygen tank. Cause still unknown. More soon.
Forgive me if this is a stupid question, but what could cause an explosion around that tank?
Elon Musk @elonmusk 29s30 seconds ago
Loss of Falcon vehicle today during propellant fill operation. Originated around upper stage oxygen tank. Cause still unknown. More soon.
Well if there is a problem with the rocket... 2 major failures in 14 months... is going to be grounded for a while.
Why, yes that is a lot, but that in no means there needs to be a long downtime. This could be a very simple fix that has complete before the pad is fully operational again
I give zero cred to a supposed ex-employee being so connected that he/she knows the cause before most likely anybody in SX does
I don't know about the ex-employee but I think it is highly likely that SX has a very good idea of what went wrong. (maybe yes, maybe not, but certainly highly likely).
Part of me hopes that it's something that is easy to fix. But if it's easy to fix, people will ask "why wasn't it detected?".True.QuoteThe COPV would be bad news as it could imply that SpaceX is unable to fix that issue.Just to be clear IIRC it was not the COPV in the LOX tank but the struts holding them that failed and (eventually) caused the COPV's to fail.
Historically COPV's have been pretty reliable components. They have (relatively) generous safety margins for space structures. They should be minimized not because of the danger but the paperwork they generate to show they've been tested and inspected. IIRC the ones on the SSME's last the life of each orbiter without replacement, roughly 30 flights each.
Yes, I know about the struts. But wasn't there a COPV problem prior to CRS-7?
VIDEO!: https://www.youtube.com/watch?v=_BgJEXQkjNQ :o
VIDEO!: https://www.youtube.com/watch?v=_BgJEXQkjNQ :ocan wait for Matthew Travis's 4K videos. Not sure if his closeup cameras would have survivied.
Given that booster passed in McGregor.
Then transported to ksc.
Nothing happened to booster during transit.
Then the gse is the only variable.
"Given that this lightbulb worked the last time I turned on the lights, it must work this time as well"
See the problem in that kind of reasoning?
VIDEO!: https://www.youtube.com/watch?v=_BgJEXQkjNQ :o
WOW. We can see the payload fall seconds after the first explosion. Maybe a dragon could fly away in time.
Elon Musk @elonmusk 29s30 seconds agoNote what this does not say.
Loss of Falcon vehicle today during propellant fill operation. Originated around upper stage oxygen tank. Cause still unknown. More soon.
can wait for Matthew Travis's 4K videos. Not sure if his closeup cameras would have survivied.
Oh, wow - I'm looking just at the first instance of visible event - it's damn sudden and energetic.Looks to me like Jim was right about this one.
Doesn't look like a fire to me, maybe an over-pressure.
1. It's a weak data point but the DC-X team were ready to re-launch 8 hrs after a previous launch. It was simply the range crew that wanted to go home that delayed it to the following day. While a smaller vehicle (and non orbital) it could be (and often is) argued that LH2 is a much less forgiving fuel to handle than RP1.
2. AFAIK the usual concern with ELV companies is slow cadence, like the time between launches of SLS for example, where there is a real risk several staff will die or retire between one launch and the next. Nothing keeps a team sharp than the chance to regularly practice their skills in a live environment.
At 3:42 there is another explosion.
That was quick.
That looks electrical on the TE. Umbilical connection shorted?
i think this is one frame before thatYep. Definitely looks centered on the edge of the stage or just to the right.
*not an expert* but i looks like the side closest to the TEL was explosing first
You and Kablooma ar right. And the wording of the spacex statement on twitter is very interesting. They say the anomaly was on the Launch Complex, so this may be GSE related (stronback bouncing, bad connections, etc..)
Has consideration ever been given to s2 static fire at McGregor?
Can't do it because it would destroy the Mvac nozzle to fire it at sea level.
Gif of the explosion. Seems the umbilical, or any other connection.there's another frame between the two you showed (look at the bird flying right to left around the lighting tower just to the right of the vehicle).
2 Questions:
Assuming this was the support equipment and a cause can be quickly identified:
1) How long will it take to repair the pad at Complex 40
Based on the flash location and the fact there was immediate ignition, the common bulkhead looks like a suspect to me.
At 3:42 there is another explosion.
That looks like RP-1, maybe from GSE that wasn't still drained back?
they were at least when they last caused a launch failure. I don't what changed for the FT variant.Based on the flash location and the fact there was immediate ignition, the common bulkhead looks like a suspect to me.
Well isn't the common bulkhead where the COPVs are on stage 2?
Based on the flash location and the fact there was immediate ignition, the common bulkhead looks like a suspect to me.
Well isn't the common bulkhead where the COPVs are on stage 2?
i think this is one frame before thatYep. Definitely looks centered on the edge of the stage or just to the right.
*not an expert* but i looks like the side closest to the TEL was explosing first
I'm wondering if the dark patch on the left side of the fireball is the remnants of the umbilical at that level (roughly the right size for that?)
The shadows on the vapor clouds from the first stage in that frame is also consistent with the explosion starting on the side of the stage.
Very strange for the explosion. There is no sign of eruption of anything before the explosion. Maybe a spark somewhere near upper stage oxygen tank?
Looks to me like Jim was right about this one.
- Ed Kyle
1) How long will it take to repair the pad at Complex 40
Based on the flash location and the fact there was immediate ignition, the common bulkhead looks like a suspect to me.
Well isn't the common bulkhead where the COPVs are on stage 2?
I think they might be located a bit higher than that.
Assuming that the x-shaped lens flare of the initial explosion is centred somewhere near the hottest point, that should theoretically be the point of failure. I've circled it on the frame immediately before the explosion.
(First explosion frame added for comparison)
Antares pad repair took about 12 months. Of course, that included wrangling about who was going to pay for it.
Looks like the payload falls down intact and then explodes...
I'm no expert, but I agree it seems like an explosion on the right side of the rocket, or beside the rocket. I also noticed debris going exactly vertical on the right side immediately after the explosion, which implies to me that the point of explosion was just to the right of the rocket rather than the rocket itself.
Doing some freeze-framing it looks like the explosion is centered around the umbilical connection.
Could that be a jet of vapor, streaming from the upper stage to the right? The light patch exactly at the point you've marked. All the other vapor in the photo is drifting to the left. Could that a leak just before the explosion?
It does seem clear that strongback was vertical and cradles closed, which puts the event before T-4:10. FTS was therefore not armed.actually with the current countdown timeline:
Correct timeline (http://spaceflight101.com/falcon-9-ft-countdown-timeline/):
Falcon 9 FT – Countdown Timeline
All Times Approximate.
Time Event
L-15:00:00 Falcon 9 to Vertical
L-10:00:00 Countdown Initiation, Launch Vehicle Power-Up
L-6:00:00 First Weather Balloon Release
L-5:00:00 Launch Area Evacuation
L-4:45:00 Range Controllers on Station
L-4:35:00 Falcon 9 Attitude Control System N2 Loading
L-5:00:00 Launch Area Evacuation
L-2:45:00 Falcon 9 RF & Telemetry Checks
L-2:30:00 Falcon 9 Launch Vehicle Release System Test
L-2:25:00 TEA-TEB Bleed In
L-1:45:00 Comm & FTS Checks
L-1:40:00 Data Flow Tests with Downrange Tracking Stations
L-1:00:00 Weather Briefing
L-0:50:00 RF Link Checks
L-0:45:00 Pre-Load Hold Point, Propellant Polls
L-0:45:00 Blast Danger Area Clear, Roadblocks Established
L-0:45:00 Flight Control System Setup (Flight Software Loading)
L-0:45:00 Final Tank Chill-In
L-0:40:00 Ready for Prop Load
L-0:38:00 Launch Readiness Poll
L-0:36:00 Tanks vented for Prop Loading
T-0:35:00 Automated Countdown Sequence, Master Script Running
T-0:34:45 Launch Enable to Flight Mode
T-0:34:30 RP-1 Flow to both Stages
T-0:33:30 Stage 1 Liquid Oxygen Loading
T-0:32:30 Confirm nominal Fuel Flow Rates
T-0:32:00 Latest Prop Flow Start
T-0:29:30 Stage 1 Helium Load
T-0:27:00 Spacecraft to Internal Power
T-0:25:30 Fuel Collector Pre-Valves Closed
T-0:25:00 All three Liquid Helium Pumps active
T-0:22:00 Stage 2 Fuel Loading Complete
T-0:19:30 Stage 2 Liquid Oxygen Loading
T-0:17:20 Stage 1 LOX Flowrate Adjustment for Stage 2 Fast Fill
T-0:13:15 Stage 2 Helium Loading
T-0:13:00 Stage 2 LOX Flow Adjustment for Helium Cryo Load
T-0:13:00 Countdown Recycle Point
T-0:12:45 Merlin 1D & MVac BTV Activation
T-0:10:15 Grid Fin Pneumatics Secured
T-0:10:05 Boostback Hazards Disabled
T-0:10:00 Stage 2 Venting for LOX Fast Fill
T-0:09:50 Flight Software Final Setups complete
T-0:09:45 TEA-TEB Ignition System Setup
T-0:09:45 Stage 2 Transmitter Re-Activation
T-0:09:30 M1D Trim Valve Cycling
T-0:09:15 Stage 1 Helium Topping
T-0:07:45 MVac Fuel Trim Valve Setup
T-0:07:30 Engine Chill Readiness
T-0:07:00 Engine Chilldown (Bleed Valves Open, both Stages
T-0:07:00 Spacecraft on Internal Power
T-0:06:45 Stage 2 Helium Transition to Pipeline
T-0:06:35 MVac Hydraulics at Bleed Pressure
T-0:06:05 M1D Engines to TVC-Null Position
T-0:05:20 Flight Computers in Self-Alignment
T-0:05:20 Stage 1 Fuel Loading Complete
T-0:05:15 Launch Vehicle Heater Deactivation
T-0:05:00 Falcon 9 to Internal Power
T-0:05:00 Range Control Comm Check
T-0:05:00 Second Stage Nitrogen Loading Termination
T-0:04:50 Pressurization for Strongback Retract
T-0:04:40 Stage 2 TVC Bleed
T-0:04:30 Stage 2 RP-1 Bleed
T-0:04:30 Stage 2 Thrust Vector Control Test
T-0:04:20 Verify Good Self-Alignment
T-0:04:10 Strongback Cradles Opening
T-0:04:00 Vehicle Release Auto Sequence
T-0:03:40 TEA-TEB Ignition System Auto Sequence
T-0:03:30 Strongback Retraction
T-0:03:25 Flight Termination System to Internal Power
T-0:03:15 FTS on Internal
T-0:03:05 Flight Termination System Armed, FTS Ready for Launch
T-0:02:55 Verify Good Mvac TVC
T-0:02:45 Fuel Trim Valve to Flight Position
T-0:02:40 Stage 1 LOX at Flight Level
T-0:02:40 FTS Countdown Sequence
T-0:02:35 Strongback Retraction Complete
T-0:02:05 Stage 2 LOX at Flight Level
T-0:02:00 Falcon 9 Transfer to Internal Power Complete
T-0:01:35 Flight Control to Self Alignment
T-0:01:30 Launch Director: Go for Launch
T-0:01:30 Final Engine Chilldown
T-0:01:25 Helium Loading Termination
T-0:01:20 Engine Purge
T-0:01:00 Flight Computer to start-up
T-0:00:50 Stage 1, Stage 2 Pressurization for Flight
T-0:00:50 First Stage Thrust Vector Actuator Test
T-0:00:30 HOLD Call for Abort
T-0:00:20 All Tanks at Flight Pressure
T-0:00:15 Arm Pyrotechnics
T-0:00:10 Latest VC Abort
T-0:00:07 Pad Deck Water Deluge System Activation
T-0:00:03 Merlin Engine Ignition
T-0:00:00 LIFTOFF
Doing some freeze-framing it looks like the explosion is centered around the umbilical connection.
Doesn't look that way to me. The umbilicals are at the 2nd stage-interstage connection, the part the explosion seems to originate at is the structural support and presumably common bulkhead location, circled in red in this image.
Check the audio, there's a small pop about 5 seconds before the sound from the actual explosions arrive.
Check the audio, there's a small pop about 5 seconds before the sound from the actual explosions arrive.
Can the FTS be activated from the initial explosion? Causing the 1st stage to unzipped.
Could that be a jet of vapor, streaming from the upper stage to the right? The light patch exactly at the point you've marked. All the other vapor in the photo is drifting to the left. Could that a leak just before the explosion?
Having gone back and forwards again in the video, it doesn't look like it.
There's another frame that I may have been skipping over, so for the sake of neatness, here are the three in sequence:
Could that be a jet of vapor, streaming from the upper stage to the right? The light patch exactly at the point you've marked. All the other vapor in the photo is drifting to the left. Could that a leak just before the explosion?
Having gone back and forwards again in the video, it doesn't look like it.
There's another frame that I may have been skipping over, so for the sake of neatness, here are the three in sequence:
I think there's too much energy in the initial explosion for it to be umbilicals.agreed. There is just not as much explosive energy in the umbilicals. If they would pop you'd get a flow or stream, which might damage later. Not this very sudden very energetic event.
I'd vote COPV, or COPV+bulkhead.
Across over the lines of glare should give the centre of the brightest part, even though the explosion itself saturated the camera.
I think there's too much energy in the initial explosion for it to be umbilicals.agreed. There is just not as much explosive energy in the umbilicals. If they would pop you'd get a flow or stream, which might damage later. Not this very sudden very energetic event.
I'd vote COPV, or COPV+bulkhead.
pressure in the stage getting released - either through COPV/associated plumbing is, imho, at this point way more likely.
Could that be a jet of vapor, streaming from the upper stage to the right? The light patch exactly at the point you've marked. All the other vapor in the photo is drifting to the left. Could that a leak just before the explosion?
Having gone back and forwards again in the video, it doesn't look like it.
There's another frame that I may have been skipping over, so for the sake of neatness, here are the three in sequence:
Anybody have any idea what that apparently rapidly moving object is? It enters the field of view from the right immediately before the explosion.
Across over the lines of glare should give the centre of the brightest part, even though the explosion itself saturated the camera.
Using the lens flare as a crosshair, it's around the point I've circled in red on the first frame.
I think there's too much energy in the initial explosion for it to be umbilicals.
I'd vote COPV, or COPV+bulkhead.
Could that be a jet of vapor, streaming from the upper stage to the right? The light patch exactly at the point you've marked. All the other vapor in the photo is drifting to the left. Could that a leak just before the explosion?
Having gone back and forwards again in the video, it doesn't look like it.
There's another frame that I may have been skipping over, so for the sake of neatness, here are the three in sequence:
Anybody have any idea what that apparently rapidly moving object is? It enters the field of view from the right immediately before the explosion. It crosses the screen in 15 frames and is in between the the lightning tower and the rocket at detonation.
Could that be a jet of vapor, streaming from the upper stage to the right? The light patch exactly at the point you've marked. All the other vapor in the photo is drifting to the left. Could that a leak just before the explosion?
Having gone back and forwards again in the video, it doesn't look like it.
There's another frame that I may have been skipping over, so for the sake of neatness, here are the three in sequence:
Peter B. de Selding:
SpaceX explosion didn't involve intentional ignition - E Musk said occurred during 2d stage fueling - & isn't covered by launch insurance.
https://twitter.com/pbdes/status/771409425475174400
Frame by frame animation...
I think there's too much energy in the initial explosion for it to be umbilicals.agreed. There is just not as much explosive energy in the umbilicals. If they would pop you'd get a flow or stream, which might damage later. Not this very sudden very energetic event.
I'd vote COPV, or COPV+bulkhead.
pressure in the stage getting released - either through COPV/associated plumbing is, imho, at this point way more likely.
Peter B. de Selding:Not covered by launch insurance. Do separate transport/handling/integration/testing policies exist? I can't imagine a $200 million asset would be totally unprotected in phases other than launch itself...
SpaceX explosion didn't involve intentional ignition - E Musk said occurred during 2d stage fueling - & isn't covered by launch insurance.
https://twitter.com/pbdes/status/771409425475174400
Check the audio, there's a small pop about 5 seconds before the sound from the actual explosions arrive.
I think that's just someone messing around a car or something near the camera.
Interestingly enough, the small first bang heard is the original S2 explosion. The big bang 3 seconds later is the fuel-air type explosion when that fireball hit the ground and mixed up the RP-1 and LOX.
In other news....
Peter B. de Selding @pbdes
Spacecom insured Amos-6 for $285M in marine cargo market, not space insurance market. Launch +1 yr policy would kick in at rocket ignition.
Peter B. de Selding @pbdes
@cbs_spacenews Sat was insured as marine cargo for pre-launch phase. Launch policy didn't kick in because no ignition-w/-intent-to-launch.
Does that mean that Spacecom won't get as much insurance payment as if this happened above ground? :-X
In other news....I'm reading this as "Spacecom will get a $285M payout from their marine cargo insurance, not <whatever amount> from their space launch insurance, since the incident happened before launch."
Peter B. de Selding @pbdes
Spacecom insured Amos-6 for $285M in marine cargo market, not space insurance market. Launch +1 yr policy would kick in at rocket ignition.
Peter B. de Selding @pbdes
@cbs_spacenews Sat was insured as marine cargo for pre-launch phase. Launch policy didn't kick in because no ignition-w/-intent-to-launch.
Does that mean that Spacecom won't get as much insurance payment as if this happened above ground? :-X
Anybody have any idea what that apparently rapidly moving object is? It enters the field of view from the right immediately before the explosion. It crosses the screen in 15 frames and is in between the the lightning tower and the rocket at detonation.
Seems to be a bird or other animal. It flies harmlessly over the rocket as it explodes.
In other news....I'm reading this as "Spacecom will get a $285M payout from their marine cargo insurance, not <whatever amount> from their space launch insurance, since the incident happened before launch."
Peter B. de Selding @pbdes
Spacecom insured Amos-6 for $285M in marine cargo market, not space insurance market. Launch +1 yr policy would kick in at rocket ignition.
Peter B. de Selding @pbdes
@cbs_spacenews Sat was insured as marine cargo for pre-launch phase. Launch policy didn't kick in because no ignition-w/-intent-to-launch.
Does that mean that Spacecom won't get as much insurance payment as if this happened above ground? :-X
I could be wrong, of course.
Me too.Check the audio, there's a small pop about 5 seconds before the sound from the actual explosions arrive.
I think that's just someone messing around a car or something near the camera.
Interestingly enough, the small first bang heard is the original S2 explosion. The big bang 3 seconds later is the fuel-air type explosion when that fireball hit the ground and mixed up the RP-1 and LOX.
I hear three distinct "initial" sounds:
1:16--a very faint "plonk" like someone hitting a PVC pipe in the distance...COPV rupture?Or:
1:18--a faint pop/bang... S2 tank rupture?
1:23--very loud boom...the LOX/RP-1 conflagration?
Check the audio, there's a small pop about 5 seconds before the sound from the actual explosions arrive.
I think that's just someone messing around a car or something near the camera.
Interestingly enough, the small first bang heard is the original S2 explosion. The big bang 3 seconds later is the fuel-air type explosion when that fireball hit the ground and mixed up the RP-1 and LOX. Check out that light pole above the number "2" bending by the generated shockwave. I wonder what the extent of damage to the hangar must be.
Anybody have any idea what that apparently rapidly moving object is? It enters the field of view from the right immediately before the explosion. It crosses the screen in 15 frames and is in between the the lightning tower and the rocket at detonation.
Seems to be a bird or other animal. It flies harmlessly over the rocket as it explodes.
I don't know man, watch it in real time, it moves so fast you can hardly see it.
Can someone point out this increase venting on S2 before the event? I keep watching it and I do not see what they are talking about.
Anybody have any idea what that apparently rapidly moving object is? It enters the field of view from the right immediately before the explosion. It crosses the screen in 15 frames and is in between the the lightning tower and the rocket at detonation.
And 12 frames after detonation another object enters the frame from the lower left and transits the fire ball at seemingly equal high velocity.
I'm breaking out my trusty tinfoil chapeau.
I wonder what the extent of damage to the hangar must be.
Can someone point out this increase venting on S2 before the event? I keep watching it and I do not see what they are talking about.
I wonder what the extent of damage to the hangar must be.
Hmm, what about the recovered cores? Are they stored in that hangar or is there another one?
Can someone point out this increase venting on S2 before the event? I keep watching it and I do not see what they are talking about.
Sorry, I meant to say 20s prior, not 10s. Venting starts at about 0:50 in the video. It may not be atypical, but I pointed it out because CRS-7 showed increased venting from the S2 starting about 20s before the stage exploded.
Not the brightness - the behavior of the hot gas. Looks like there was stored energy.I think there's too much energy in the initial explosion for it to be umbilicals.agreed. There is just not as much explosive energy in the umbilicals. If they would pop you'd get a flow or stream, which might damage later. Not this very sudden very energetic event.
I'd vote COPV, or COPV+bulkhead.
pressure in the stage getting released - either through COPV/associated plumbing is, imho, at this point way more likely.
The brightness can just be burning. Don't mistake an oversaturated image for lots of energy.
SpaceX policy begun this yr of putting sats on rocket for static tests to trim a day frm launch campaign caused insurer upset, but not alot (sic).
It looks to me to be an U/S LOX tank rupture, possibly at the common bulkhead. That will at the very least mean a careful look at the design of said bulkhead and how it attaches to the two prop tanks and possibly a redesign.
The good news? As the fault appears to be in the upper stage, the recycled cores should still be clear for reuse.
Not the brightness - the behavior of the hot gas. Looks like there was stored energy.I think there's too much energy in the initial explosion for it to be umbilicals.agreed. There is just not as much explosive energy in the umbilicals. If they would pop you'd get a flow or stream, which might damage later. Not this very sudden very energetic event.
I'd vote COPV, or COPV+bulkhead.
pressure in the stage getting released - either through COPV/associated plumbing is, imho, at this point way more likely.
The brightness can just be burning. Don't mistake an oversaturated image for lots of energy.
Even if the source was internal (e.g. COPV) the center of the ignition may be just outside
Not the brightness - the behavior of the hot gas. Looks like there was stored energy.I think there's too much energy in the initial explosion for it to be umbilicals.agreed. There is just not as much explosive energy in the umbilicals. If they would pop you'd get a flow or stream, which might damage later. Not this very sudden very energetic event.
I'd vote COPV, or COPV+bulkhead.
pressure in the stage getting released - either through COPV/associated plumbing is, imho, at this point way more likely.
The brightness can just be burning. Don't mistake an oversaturated image for lots of energy.
Even if the source was internal (e.g. COPV) the center of the ignition may be just outside
True. Still seems a bit much, but definitely possibleNot the brightness - the behavior of the hot gas. Looks like there was stored energy.I think there's too much energy in the initial explosion for it to be umbilicals.agreed. There is just not as much explosive energy in the umbilicals. If they would pop you'd get a flow or stream, which might damage later. Not this very sudden very energetic event.
I'd vote COPV, or COPV+bulkhead.
pressure in the stage getting released - either through COPV/associated plumbing is, imho, at this point way more likely.
The brightness can just be burning. Don't mistake an oversaturated image for lots of energy.
Even if the source was internal (e.g. COPV) the center of the ignition may be just outside
If th source had leaked for even a short time before ignition, the combustible material could spread quickly, particularly if boiling rapidly. When ignited the flames would spread very fast, even if there wasn't a massive amount of energy in the explosion.
I wonder what the extent of damage to the hangar must be.
Hmm, what about the recovered cores? Are they stored in that hangar or is there another one?
They are stored in the LC-39A HIF, some 3 miles away from LC-40.
Peter B. de Selding:
SpaceX explosion didn't involve intentional ignition - E Musk said occurred during 2d stage fueling - & isn't covered by launch insurance.
https://twitter.com/pbdes/status/771409425475174400
Not the brightness - the behavior of the hot gas. Looks like there was stored energy.I think there's too much energy in the initial explosion for it to be umbilicals.agreed. There is just not as much explosive energy in the umbilicals. If they would pop you'd get a flow or stream, which might damage later. Not this very sudden very energetic event.
I'd vote COPV, or COPV+bulkhead.
pressure in the stage getting released - either through COPV/associated plumbing is, imho, at this point way more likely.
The brightness can just be burning. Don't mistake an oversaturated image for lots of energy.
Even if the source was internal (e.g. COPV) the center of the ignition may be just outside
Everyone posting v1.0 or v1.1-pre-FT timelines, please stop. Consider removing your posts. It's actively unhelpful. Fuel loading procedures changed significantly for 1.1 FT with its supercooled propellants.
For that matter, we don't even know if the failure happened around T-5 or T-3 yet.
True. Still seems a bit much, but definitely possibleNot the brightness - the behavior of the hot gas. Looks like there was stored energy.I think there's too much energy in the initial explosion for it to be umbilicals.agreed. There is just not as much explosive energy in the umbilicals. If they would pop you'd get a flow or stream, which might damage later. Not this very sudden very energetic event.
I'd vote COPV, or COPV+bulkhead.
pressure in the stage getting released - either through COPV/associated plumbing is, imho, at this point way more likely.
The brightness can just be burning. Don't mistake an oversaturated image for lots of energy.
Even if the source was internal (e.g. COPV) the center of the ignition may be just outside
If th source had leaked for even a short time before ignition, the combustible material could spread quickly, particularly if boiling rapidly. When ignited the flames would spread very fast, even if there wasn't a massive amount of energy in the explosion.
It probably means many lawyers are pressing their suits and preparing for battle...
It probably means many lawyers are pressing their suits and preparing for battle...
Nothing for them to do.
This means SpaceX will have to foot most of the bill if they ever want to see another customer
Or maybe SpaceX has their own property/liability insurance which would cover this.
Peter B. de Selding:
SpaceX explosion didn't involve intentional ignition - E Musk said occurred during 2d stage fueling - & isn't covered by launch insurance.
https://twitter.com/pbdes/status/771409425475174400
Ouch. So Spacecom has to eat the cost?
I wonder what the extent of damage to the hangar must be.
Hmm, what about the recovered cores? Are they stored in that hangar or is there another one?
They are stored in the LC-39A HIF, some 3 miles away from LC-40.
As I noted upthread (now waaay upthread), the LC39A HIF is rather close to pad 39A. Imagine a similar scenario, but with a FH on (that) pad...
It probably means many lawyers are pressing their suits and preparing for battle...
Nothing for them to do.
This means SpaceX will have to foot most of the bill if they ever want to see another customer.
There's no way a shipping insurance will cover this.
41m41 minutes ago
Peter B. de Selding @pbdes
@cbs_spacenews Sat was insured as marine cargo for pre-launch phase. Launch policy didn't kick in because no ignition-w/-intent-to-launch.
More from Peter B. de Selding on Twitter:QuoteSpaceX policy begun this yr of putting sats on rocket for static tests to trim a day frm launch campaign caused insurer upset, but not alot (sic).
I’ll go out on a limb and predict that we don’t see any more comm sats on rockets for static fire tests after this any time soon.
It probably means many lawyers are pressing their suits and preparing for battle...
Nothing for them to do.
This means SpaceX will have to foot most of the bill if they ever want to see another customer.
There's no way a shipping insurance will cover this.
Are you sure? PBdSelding later tweeted that the pre-launch phase was insured as marine cargo for $285 mil.
I am kind of thinking that maybe they really didn't fix the problem that caused the CRS-7 failure. My spidey senses are telling me this. Watching the CRS-7 videos again its seems to be just too similar. Especially considering the 2nd stage wasn't even firing when the explosion happened again.
I know this is pure speculation at this point but what else are we do today.
Why? If the customer chose not to get full "space-industry" insurance then that is their prerogative, but they will bear the cost.
Are you sure? PBdSelding later tweeted that the pre-launch phase was insured as marine cargo for $285 mil.
Yes, but if that's the case... if I'm not totally mistaken that kind of insurance is for transportation and associated handling. Which is why the rate is lower, these are lower-risk events.
However, putting the payload on top of a fully fueled LV during a test firing is not a normal shipping procedure and would not be covered.
It's like with a rental car: even if you buy all the insurance, if you then go to a skid track and do some crash car racing with it, good luck claiming any damages...
Except this was standard procedure (static fire after integration)
Perhaps this has been mentioned and exhausted somewhere in the many posts today, if it has I apologize.LOX vent valve clogged/closed unexpectedly m
The venting nearer the top of the TE stops a few seconds before the fireworks.
1) Is it safe to assume that is second stage LOx?
2) Was that normal for that point in time?
Except this was standard procedure (static fire after integration)
Not for every Spacex launch and for none of the other ones.
https://www.youtube.com/watch?v=ZX1vdPjCh3QI think Kabloona might be onto something.
not sure if they got permission from US Launch Report but here is a video with the audio synced
I hear three distinct "initial" sounds:Crank up the volume, the first sound could be the creak of metal bending. If that's the case, we might be hearing a strut bend and break, a COPV rupturing or helium hose popping, and the loud boom is the visible explosion.
1:16--a very faint "plonk" like someone hitting a PVC pipe with a hammer in the distance...COPV rupture?
1:18--a faint pop/bang... S2 tank rupture?
1:23--very loud boom...the LOX/RP-1 explosion?
That first sound at 1:16 is unusual and seems to me like it may be the initiating event. A COPV or high pressure line/fitting letting go followed by S2 tank rupture 1-2 seconds later seems consistent.
Why? If the customer chose not to get full "space-industry" insurance then that is their prerogative, but they will bear the cost.
Well, it was SpaceX destroying the cargo.
Of course they might have a contract explicitly stating that if SpaceX does risky things with the cargo they won't be liable for it but I can't imagine any customer being so stupid to sign something like that.
No, this will be SpaceX's bill, but there's quite some chance they have own coverage for at least some of it.
Except this was standard procedure (static fire after integration)That kind of thing is not a standard practice for marine cargo. Heck, it isn't even for SpaceX let alone other launch providers.
and I can't imagine them buying satellite insurance with a giant hole in it after shipment to the Cape.Well, if SpaceX (+ whatever insurance they have) covers extraordinary events it in between, why not?
Plenty of bad things can happen during integration, satellite gets damaged by accident, a hurricane destroys the HIF, etc. All of those you buy insurance for.Yes, and all these things _are_ standard risks for any kind of high-value target.
Except this was standard procedure (static fire after integration)That kind of thing is not a standard practice for marine cargo. Heck, it isn't even for SpaceX let alone other launch providers.Quoteand I can't imagine them buying satellite insurance with a giant hole in it after shipment to the Cape.Well, if SpaceX (+ whatever insurance they have) covers extraordinary events it in between, why not?QuotePlenty of bad things can happen during integration, satellite gets damaged by accident, a hurricane destroys the HIF, etc. All of those you buy insurance for.Yes, and all these things _are_ standard risks for any kind of high-value target.
Not for every Spacex launch and for none of the other ones.
Crank up the volume, the first sound could be the creak of metal bending. If that's the case, we might be hearing a strut bend and break
I've spent a lot of professional time parsing insurance contracts. Unless you've seen the applicable policy and all the riders thereto, you have no way to be quite as authoritative about coverage issues IN THIS INSTANCE.
I think Kabloona might be onto something.I hear three distinct "initial" sounds:Crank up the volume, the first sound could be the creak of metal bending. If that's the case, we might be hearing a strut bend and break, a COPV rupturing or helium hose popping, and the loud boom is the visible explosion.
1:16--a very faint "plonk" like someone hitting a PVC pipe with a hammer in the distance...COPV rupture?
1:18--a faint pop/bang... S2 tank rupture?
1:23--very loud boom...the LOX/RP-1 explosion?
That first sound at 1:16 is unusual and seems to me like it may be the initiating event. A COPV or high pressure line/fitting letting go followed by S2 tank rupture 1-2 seconds later seems consistent.
Will this lead to new SpaceX procedures for quick 'n easy mating of the payload after static test firing. Should make for more aggressive, safety-enhancing testing.
The flame in the first frames looks more characteristic of detonation than conflagration to my amateur eyes; it's sharp and white all around.
These screen shots were posted by @John_Gardi on Twitter. Taken from this slow-mo video.
These screen shots were posted by @John_Gardi on Twitter. Taken from this slow-mo video. ...Seems to me that there is a bunch of software interpolation creating "detail" not in the source video. In other words, I think it's inventing frames to smooth the transitions.
We had a follow-up that it wasn't a medevac, the firefighter just wanted a lift to better observe the fire from above.
Thanks for posting the video. Boy, watching the payload tumble to the ground/from the cradle after the fact sure adds insult to injury...
Again, my thoughts are with all involved. Glad there weren't any injuries (any followup to reports that a firefighter was injured?)
Watching this in slow motion, it appears that in the first frame with fire that there is a long downward finger of flame and smoke that dissipates as the fire ball erupts. Is there an umbilical that could have come off and sprayed something downward?Some of that looks to me looks like it could be light from the initial fireball illuminating preexisting vapor clouds around the top of the first stage.
I believe this was a pre-detonation of the either a portion of, or completely of the upper stage FTS. There was an intense flash at a single small point. You don't get that level of intense flashes from an ignition. If this was a COPV explosion we should be seeing a spray of LOX or fuel before the explosion occurs.FTS was safed at the time, as evidenced in the timeline by cradle closed and strongback vertical.
My two cents. I might know the cause in my completely unfounded opinion. The main thing that I'm drawing my thoughts from are the intense localized flash of the explosion (as noticed by the flash star in the video film).
I believe this was a pre-detonation of the either a portion of, or completely of the upper stage FTS. There was an intense flash at a single small point. You don't get that level of intense flashes from an ignition. If this was a COPV explosion we should be seeing a spray of LOX or fuel before the explosion occurs.
I look forward to the date that rockets get their FTS removed. Having explosives on a vehicle has always seemed like a bad idea to me despite the good reasons for protection of the public they allow.
Made a little gif. Don't know how accurate it is:
(https://i.makeagif.com/media/9-01-2016/psm9zl.gif)
Accidentally (or deliberately) activated FTS would have activated the FTS for the entire vehicle, not just the second stage. This failure was too localized to be FTS.That exactly looks like what happened. The whole stack just exploded really fast.
1h1 hour ago
Jeff Foust @jeff_foust
You’ll see a lot of amateur speculation and analysis of today’s F9 explosion. Use with caution; almost all of it will turn out to be wrong.
Made a little gif. Don't know how accurate it is:
(https://i.makeagif.com/media/9-01-2016/psm9zl.gif)
It's hard to draw much from attempting to find the 2D mid-point of an over-exposure.
No, it doesn't. There was a very bright and fast event on the second stage near the oxygen tank. That opened the kerosene tank, and then the burning fuel and debris falling downward tore apart and ignited the first stage. A FTS trigger would have been simultaneous on the first and second stages, not starting on the second stage and then proceeding downward like this was.Accidentally (or deliberately) activated FTS would have activated the FTS for the entire vehicle, not just the second stage. This failure was too localized to be FTS.That exactly looks like what happened. The whole stack just exploded really fast.
Accidentally (or deliberately) activated FTS would have activated the FTS for the entire vehicle, not just the second stage. This failure was too localized to be FTS.That exactly looks like what happened. The whole stack just exploded really fast.
Made a little gif. Don't know how accurate it is:
(https://i.makeagif.com/media/9-01-2016/psm9zl.gif)
It's hard to draw much from attempting to find the 2D mid-point of an over-exposure.
That's why most people that attempt to locate it use the diffraction spikes instead (hence the X shape above). They are much more localized as they trace out the highest intensity light source at that instant. It's reasonable to assume that's where the event originated.
Wise words from Jeff Foust.Quote1h1 hour ago
Jeff Foust @jeff_foust
You’ll see a lot of amateur speculation and analysis of today’s F9 explosion. Use with caution; almost all of it will turn out to be wrong.
Made a little gif. Don't know how accurate it is:
(https://i.makeagif.com/media/9-01-2016/psm9zl.gif)
It's hard to draw much from attempting to find the 2D mid-point of an over-exposure.
That's why most people that attempt to locate it use the diffraction spikes instead (hence the X shape above). They are much more localized as they trace out the highest intensity light source at that instant. It's reasonable to assume that's where the event originated.
FH is worst case equivalent to 196 tons of TNT. The HIF is 1900 feet from LC-39A, and at that range the only effect should be some broken windows, and possibly some falling flamey bits - but neither are likely to cause major damage to a steel building or anything reasonably sturdy inside it.
I'm going to speculate wildly here (Mod, please delete if inappropriate);
Point 1; The CRX7 failure occurred in the second stage.
Point 2; This explosion *appears* to have originated in the second stage.
Speculation: to my eyes, this event appears to have been highly energetic from the first moment it appears.
Further speculation; would a COPV failure (sudden release of He into the LOX) fit observations?
Some notes:
1. There's no similarity to CRS-7 event. "Excessive venting" that some people claim here is probably mostly due to the fact that surrounding air was almost saturated with moisture. Pressure vessel overpressure rupture would have caused massive cloud initially, which then would have perhaps detonated. Not the other way around.
Watching this in slow motion, it appears that in the first frame with fire that there is a long downward finger of flame and smoke that dissipates as the fire ball erupts. Is there an umbilical that could have come off and sprayed something downward?
Wise words from Jeff Foust.Quote1h1 hour ago
Jeff Foust @jeff_foust
You’ll see a lot of amateur speculation and analysis of today’s F9 explosion. Use with caution; almost all of it will turn out to be wrong.
Agreed, thus why I explicitly put a low emphasis in my post.
Wise words from Jeff Foust.Quote1h1 hour ago
Jeff Foust @jeff_foust
You’ll see a lot of amateur speculation and analysis of today’s F9 explosion. Use with caution; almost all of it will turn out to be wrong.
Agreed, thus why I explicitly put a low emphasis in my post.
Made a little gif. Don't know how accurate it is:
(https://i.makeagif.com/media/9-01-2016/psm9zl.gif)
It's hard to draw much from attempting to find the 2D mid-point of an over-exposure.
That's why most people that attempt to locate it use the diffraction spikes instead (hence the X shape above). They are much more localized as they trace out the highest intensity light source at that instant. It's reasonable to assume that's where the event originated.
Sorry, but in this case, those spikes (actually in-lens reflections) show the average center of the oversaturated fireball. Nothing else.
The biggest thing I don't understand is what is the ignition source? Even if the O2 tank had an overpressure, underpressure, or any other failure mode, why would the first thing we see be blinding fire? Some static or something would probably catch it eventually, but without the engines running you could mix O2 and RP-1 and it would still not self detonate.
Am I missing something? I realize my optimism toward SpaceX might make me favor the least damaging outcome, but I just don't see how anything other than an explosive charge could have detonated so quickly. TEA-TEB or hypergolics could easily cause a bad day, but they don't appear to have been involved unless they were being loaded into S2 by the umbilical at the time.
Sorry, but in this case, those spikes (actually in-lens reflections) show the average center of the oversaturated fireball. Nothing else.
Accidentally (or deliberately) activated FTS would have activated the FTS for the entire vehicle, not just the second stage. This failure was too localized to be FTS.That exactly looks like what happened. The whole stack just exploded really fast.
It really didn't. There was a localized explosion in the second stage with a relatively slow progressive failure down the stack. If it was FTS, the whole vehicle would have ceased to exist in the span of two or three frames.
Indeed. You might call this a *static*fire*. Heh.The biggest thing I don't understand is what is the ignition source? Even if the O2 tank had an overpressure, underpressure, or any other failure mode, why would the first thing we see be blinding fire? Some static or something would probably catch it eventually, but without the engines running you could mix O2 and RP-1 and it would still not self detonate.
Am I missing something? I realize my optimism toward SpaceX might make me favor the least damaging outcome, but I just don't see how anything other than an explosive charge could have detonated so quickly. TEA-TEB or hypergolics could easily cause a bad day, but they don't appear to have been involved unless they were being loaded into S2 by the umbilical at the time.
If the fuel-oxygen mix is right, it only takes a tiny spark. Electrostatic discharge, a momentary arc from a switch opening or closing, really anything...
Accidentally (or deliberately) activated FTS would have activated the FTS for the entire vehicle, not just the second stage. This failure was too localized to be FTS.That exactly looks like what happened. The whole stack just exploded really fast.
It really didn't. There was a localized explosion in the second stage with a relatively slow progressive failure down the stack. If it was FTS, the whole vehicle would have ceased to exist in the span of two or three frames.
FTS isn't designed to obliterate the vehicle as much as it is to release the fuel to get rid of its mass, momentum, and explosive potential. When we've seen FTS before it causes a slow conflagration fireball just like we see here after that initial pop at the top of S2. It looked very much like the fireball we saw on GH2, although with a much better vantage point to see details.
For those saying FTS wouldn't cause a fireball, well, what other ignition source was there? We didn't see a green flash.
The vehicle is sitting in a cloud of concentrated, evaporating oxygen and is holding thousands of kilograms more on board. A small leak and a spark is all that is needed to cause an event big enough to rupture the tanks leading the chain reaction. Oxygen is abundant in this scenario - we don't need an explosive to turn the situation bad.
In a sufficiently high concentration of oxygen, many traditionally nonflammable things become quite flammable.The vehicle is sitting in a cloud of concentrated, evaporating oxygen and is holding thousands of kilograms more on board. A small leak and a spark is all that is needed to cause an event big enough to rupture the tanks leading the chain reaction. Oxygen is abundant in this scenario - we don't need an explosive to turn the situation bad.
Oxygen alone will not cause an explosion. It does not react with itself. You need a fuel source.
I heard from one of the reddit that some believe a hydrazine leak from the satellite may of caused the initial explosion. Given the location of the explosion being close the top of the oxygen tank, and the initial size explosion it seems like this is certainly possible. I know from chemistry that hydrazine is particularly reactive, volatile, and very dangerous. I am not an expert on launch systems and satellites, but what is the likelihood that this was the case.
The vehicle is sitting in a cloud of concentrated, evaporating oxygen and is holding thousands of kilograms more on board. A small leak and a spark is all that is needed to cause an event big enough to rupture the tanks leading the chain reaction. Oxygen is abundant in this scenario - we don't need an explosive to turn the situation bad.
13,000 gallons of liquid oxygen and a full load of fuel sloshed over the stand and the nearby terrain.
Wonder how the Dragon2 Trunk/Capsule would have dealt with this 2nd Stage RUD in a Pad Abort scenario?
Check the audio, there's a small pop about 5 seconds before the sound from the actual explosions arrive.
I think that's just someone messing around a car or something near the camera.
Interestingly enough, the small first bang heard is the original S2 explosion. The big bang 3 seconds later is the fuel-air type explosion when that fireball hit the ground and mixed up the RP-1 and LOX.
I hear three distinct "initial" sounds:
1:16--a very faint "plonk" like someone hitting a PVC pipe with a hammer in the distance...COPV rupture?
1:18--a faint pop/bang... S2 tank rupture?
1:23--very loud boom...the LOX/RP-1 explosion?
That first sound at 1:16 is unusual and seems to me like it may be the initiating event. A COPV or high pressure line/fitting letting go followed by S2 tank rupture 1-2 seconds later seems consistent.
Indeed. You might call this a *static*fire*. Heh.The biggest thing I don't understand is what is the ignition source? Even if the O2 tank had an overpressure, underpressure, or any other failure mode, why would the first thing we see be blinding fire? Some static or something would probably catch it eventually, but without the engines running you could mix O2 and RP-1 and it would still not self detonate.
Am I missing something? I realize my optimism toward SpaceX might make me favor the least damaging outcome, but I just don't see how anything other than an explosive charge could have detonated so quickly. TEA-TEB or hypergolics could easily cause a bad day, but they don't appear to have been involved unless they were being loaded into S2 by the umbilical at the time.
If the fuel-oxygen mix is right, it only takes a tiny spark. Electrostatic discharge, a momentary arc from a switch opening or closing, really anything...
I heard from one of the reddit that some believe a hydrazine leak from the satellite may of caused the initial explosion. Given the location of the explosion being close the top of the oxygen tank, and the initial size explosion it seems like this is certainly possible. I know from chemistry that hydrazine is particularly reactive, volatile, and very dangerous. I am not an expert on launch systems and satellites, but what is the likelihood that this was the case.
I heard from one of the reddit that some believe a hydrazine leak from the satellite may of caused the initial explosion. Given the location of the explosion being close the top of the oxygen tank, and the initial size explosion it seems like this is certainly possible. I know from chemistry that hydrazine is particularly reactive, volatile, and very dangerous. I am not an expert on launch systems and satellites, but what is the likelihood that this was the case.
Probably near zero. The payload was well above the plane where the first flash occurred, encapsulated in a fairing that remained intact long after the initial explosion. Also there's no way for hydrazine to get *into* the LOX tank, which appeared to rupture, suggesting the event may have started inside the LOX tank.
Wonder how the Dragon2 Trunk/Capsule would have dealt with this 2nd Stage RUD in a Pad Abort scenario?
Crank up the volume, the first sound could be the creak of metal bending. If that's the case, we might be hearing a strut bend and break, a COPV rupturing or helium hose popping, and the loud boom is the visible explosion.
FTS is designed to cease acceleration and disperse the propellants. This is often accomplished by a linear shaped charge running the length of the vehicle. I suspect the Falcon is the same way. You might not see an immediate fireball, but you would see the whole vehicle unzip basically at once if it were FTS, not the several seconds it took to completely come apart.
Crank up the volume, the first sound could be the creak of metal bending. If that's the case, we might be hearing a strut bend and break, a COPV rupturing or helium hose popping, and the loud boom is the visible explosion.
Please... This is an incessant problem on the internet to attribute new failures to previous issues. In engineering its the exception rather than the rule that a new failure is the same failure as before. If something fails its almost certainly something else that failed unless your engineers have no clue what they're doing or root cause was not found. This failure is NOT going to be related to struts. Forget the struts exist. That's a solved problem. Different metal suppliers, different stronger design, additional struts, impossible to be the same problem.
Sorry, but there is oversaturation and then there is oversaturation. According to you, those spikes should simply be as wide as the whited-out region, which is clearly not the case. My point is that it takes even more light intensity to produce spiking than it takes to saturate the detector at a region and that it was reasonable to assume that the highest physical brightness point corresponds to the point of origin. The spikes convey additional useful information about the brightness profile above the whited-out region precisely because they are more tightly constrained.
I heard from one of the reddit that some believe a hydrazine leak from the satellite may of caused the initial explosion. Given the location of the explosion being close the top of the oxygen tank, and the initial size explosion it seems like this is certainly possible. I know from chemistry that hydrazine is particularly reactive, volatile, and very dangerous. I am not an expert on launch systems and satellites, but what is the likelihood that this was the case.
Probably near zero. The payload was well above the plane where the first flash occurred, encapsulated in a fairing that remained intact long after the initial explosion. Also there's no way for hydrazine to get *into* the LOX tank, which appeared to rupture, suggesting the event may have started inside the LOX tank.
That is exactly my point though, the mixture isn't right. They are totally separate until something goes wrong. It seems a stretch to think the O2 tank popped, which popped the RP-1 tank, and static happened at the right time and place to cause a spark, all within a few milliseconds. We should have seen a tank pop before it all went up.
Wouldn't the color of the initial detonation (orange) suggest an RP-1 leak?
Please... This is an incessant problem on this forum to attribute new failures to previous issues. In engineering its the exception rather than the rule that a new failure is the same failure as before. If something fails its almost certainly something else that failed unless your engineers have no clue what they're doing or root cause was not found. This failure is NOT going to be related to struts. Forget the struts exist. That's a solved problem. Different metal suppliers, different stronger design, additional struts, impossible to be the same problem.
I dunno, ever heard of Taurus, OCO, and Glory? Just saying...
Accidentally (or deliberately) activated FTS would have activated the FTS for the entire vehicle, not just the second stage. This failure was too localized to be FTS.That exactly looks like what happened. The whole stack just exploded really fast.
It really didn't. There was a localized explosion in the second stage with a relatively slow progressive failure down the stack. If it was FTS, the whole vehicle would have ceased to exist in the span of two or three frames.
FTS isn't designed to obliterate the vehicle as much as it is to release the fuel to get rid of its mass, momentum, and explosive potential. When we've seen FTS before it causes a slow conflagration fireball just like we see here after that initial pop at the top of S2. It looked very much like the fireball we saw on GH2, although with a much better vantage point to see details.
For those saying FTS wouldn't cause a fireball, well, what other ignition source was there? We didn't see a green flash.
FTS is designed to cease acceleration and disperse the propellants. This is often accomplished by a linear shaped charge running the length of the vehicle. I suspect the Falcon is the same way. You might not see an immediate fireball, but you would see the whole vehicle unzip basically at once if it were FTS, not the several seconds it took to completely come apart.
The vehicle is sitting in a cloud of concentrated, evaporating oxygen and is holding thousands of kilograms more on board. A small leak and a spark is all that is needed to cause an event big enough to rupture the tanks leading the chain reaction. Oxygen is abundant in this scenario - we don't need an explosive to turn the situation bad.
someone posted this upthread, but lot of fuel and LOx mixing without an explosion: Atlas 190D
https://www.youtube.com/watch?v=FmrrcAVOV4s (https://www.youtube.com/watch?v=FmrrcAVOV4s)Quote13,000 gallons of liquid oxygen and a full load of fuel sloshed over the stand and the nearby terrain.
here's a reference:
https://books.google.com/books?id=OVNuxBlXFHYC&lpg=PA32&ots=RWbZyy0by-&dq=1963%2C%20Atlas%20190D&pg=PA32#v=onepage&q=1963,%20Atlas%20190D&f=false (https://books.google.com/books?id=OVNuxBlXFHYC&lpg=PA32&ots=RWbZyy0by-&dq=1963%2C%20Atlas%20190D&pg=PA32#v=onepage&q=1963,%20Atlas%20190D&f=false)
The launch crew managed to
drain the LOX tank but ended up depressurizing it in the process, and so
it collapsed, dropping the Agena.
That is exactly my point though, the mixture isn't right. They are totally separate until something goes wrong. It seems a stretch to think the O2 tank popped, which popped the RP-1 tank, and static happened at the right time and place to cause a spark, all within a few milliseconds. We should have seen a tank pop before it all went up.
That is exactly my point though, the mixture isn't right. They are totally separate until something goes wrong. It seems a stretch to think the O2 tank popped, which popped the RP-1 tank, and static happened at the right time and place to cause a spark, all within a few milliseconds. We should have seen a tank pop before it all went up.
That's what i believe too.
At least with a copv bursting, it would send shrapnel through the tank walls into the fuel tank causing mixing. someone mentioned upthread that the bursting of a copv might have enough energy to start the chemical chain reaction (not the kind of "classical" ignition source you'd imagine like a flame or spark), and the copv carbon would be flammable in a high oxygen environment.
I think there's evidence that the explosion initiated to the side of the rocket, not on or in the rocket. The USLaunchReport video as a reference. There is a fragment that has a trajectory that traces back to the strongback, not the rocket. Reference images attached
I think there's evidence that the explosion initiated to the side of the rocket, not on or in the rocket. The USLaunchReport video as a reference. There is a fragment that has a trajectory that traces back to the strongback, not the rocket. Reference images attached
I think there's evidence that the explosion initiated to the side of the rocket, not on or in the rocket. The USLaunchReport video as a reference. There is a fragment that has a trajectory that traces back to the strongback, not the rocket. Reference images attached
Interesting. Can be ballistically reconstructed. Anyone up for this?
So what is Object X?
I think there's evidence that the explosion initiated to the side of the rocket, not on or in the rocket. The USLaunchReport video as a reference. There is a fragment that has a trajectory that traces back to the strongback, not the rocket. Reference images attached
So what is Object X?
So what is Object X?
i think what you circled on the left side is some liquid oxygen that is being pushed away
and what you circled on the right side is the claw that holds onto the stage that is part of the Erector
I think there's evidence that the explosion initiated to the side of the rocket, not on or in the rocket. The USLaunchReport video as a reference. There is a fragment that has a trajectory that traces back to the strongback, not the rocket. Reference images attached
it could also coming toward the camera.
WOW. We can see the payload fall seconds after the first explosion. Maybe a dragon could fly away in time.
Maybe the crew Dragon but not the cargo Dragon. The cargo Dragon can now survive a CRS-7 type accident by deploying its parachutes but that doesn't help if the accident is at the pad.
WOW. We can see the payload fall seconds after the first explosion. Maybe a dragon could fly away in time.
Maybe the crew Dragon but not the cargo Dragon. The cargo Dragon can now survive a CRS-7 type accident by deploying its parachutes but that doesn't help if the accident is at the pad.
It's hard to know if people would have survived if they had been in a crew Dragon on this rocket. If there was no warning, the Dragon would have been subjected to a significant overpressure before it could have taken off. Maybe the Dragon could have protected crew members from such an overpressure, maybe not.
There's also the issue of whether the overpressure would have damaged the SuperDraco engines and/or their prop tanks and/or the abort control system. If any of those things failed, the crew would have died.
(In this scenario) It was the trunk I was most concerned with as a Crew Abort needs the trunk healthy and fully attached for proper abort profiles. (COG, etc)WOW. We can see the payload fall seconds after the first explosion. Maybe a dragon could fly away in time.
Maybe the crew Dragon but not the cargo Dragon. The cargo Dragon can now survive a CRS-7 type accident by deploying its parachutes but that doesn't help if the accident is at the pad.
It's hard to know if people would have survived if they had been in a crew Dragon on this rocket. If there was no warning, the Dragon would have been subjected to a significant overpressure before it could have taken off. Maybe the Dragon could have protected crew members from such an overpressure, maybe not.
There's also the issue of whether the overpressure would have damaged the SuperDraco engines and/or their prop tanks and/or the abort control system. If any of those things failed, the crew would have died.
WOW. We can see the payload fall seconds after the first explosion. Maybe a dragon could fly away in time.
Maybe the crew Dragon but not the cargo Dragon. The cargo Dragon can now survive a CRS-7 type accident by deploying its parachutes but that doesn't help if the accident is at the pad.
It's hard to know if people would have survived if they had been in a crew Dragon on this rocket. If there was no warning, the Dragon would have been subjected to a significant overpressure before it could have taken off. Maybe the Dragon could have protected crew members from such an overpressure, maybe not.
There's also the issue of whether the overpressure would have damaged the SuperDraco engines and/or their prop tanks and/or the abort control system. If any of those things failed, the crew would have died.
One thought re: speculation about a COPV failure. The COTS-7 failure wasn't thought to be a COPV letting go per se, but a massive helium leak that led to an overpressure. A COPV flat-out failing might happen faster, and could lead to a more energetic explosion. For instance, isn't that how the S-IVB 503 upper stage was lost during a ground test (in very similar circumstances--during fueling before a hot-fire test)?
~Jon
The group finally traced the source of the explosion to one of the eight ambient-temperature helium storage spheres located on the thrust structure of the J -2 engine. The exploding sphere ruptured the propellant fill lines, allowing liquid oxygen and liquid hydrogen to mix and ignite, setting off an explosion that wrecked the stage. Further analysis showed that the sphere had been welded with pure titanium weld material, rather than the alloy material specified.
So what is Object X?
That's what I was calling evidence of the LOX tank rupturing at top left, near the vents.
Does look like a panel has opened as the black outlined object looks solid under enhancement and something is venting out to the left.
It could also be a JPEG/MPEG compression artifact, which create hard edges where none actually exist.Does look like a panel has opened as the black outlined object looks solid under enhancement and something is venting out to the left.
You have to be careful in over-interpreting the dark "thing." The flame is back-lighting an oxygen vapor cloud, and the camera's response and dynamic lighting conditions might be doing very weird things. Notice how the shroud looks black on the left-hand edge in your cropped center frame? It *could* be a piece of debris, or it could be a curl of vapor.
NASA Statement on SpaceX Incident
Press Release From: NASA HQ
Posted: Thursday, September 1, 2016
“We remain confident in our commercial partners and firmly stand behind the successful 21st century launch complex that NASA, other federal agencies, and U.S. commercial companies are building on Florida’s Space Coast. Today’s incident -- while it was not a NASA launch -- is a reminder that spaceflight is an incredible challenge, but our partners learn from each success and setback.
“The situation at the Cape is being evaluated, and it’s too early to know whether the incident will affect the schedule for upcoming NASA-related SpaceX launches to the International Space Station. If there are SpaceX mission delays, other cargo spacecraft will be able to meet the station’s cargo needs, and supplies and research investigations are at good levels.
“The launch for NASA’s OSIRIS-REx mission remains on track for Sept. 8. Initial assessments indicate the United Launch Alliance Atlas V rocket and OSIRIS-REx spacecraft are healthy and secure in the Vertical Integration Facility at Space Launch Complex-41, which is 1.1 miles from SpaceX’s launch pad where the incident occurred.”
// end //
From: http://spaceref.com/news/viewpr.html?pid=49385
Further, look at the symmetry of the expanding LOX cloud a few frames later. The right side is a bit muffled because of the interference with the T/E, obviously, but the near perfect oval shape for most of its circumference suggests the failure point was mostly toward the camera, not facing directly at the erector.
Every time we have one on these events my thoughts are always the same. Better now than when we have a crew on board. Pick up the pieces, find the cause(s), fix them and get flying again. Best of luck to the teams at SpaceX.
Every time we have one on these events my thoughts are always the same. Better now than when we have a crew on board. Pick up the pieces, find the cause(s), fix them and get flying again. Best of luck to the teams at SpaceX.
Every time we have one on these events my thoughts are always the same. Better now than when we have a crew on board. Pick up the pieces, find the cause(s), fix them and get flying again. Best of luck to the teams at SpaceX.
Yes, and this is exactly why I think it's so much more dangerous to put a crew on SLS than a crew on either commercial crew vehicle. Atlas V and Falcon 9 have lots of non-crew launches to find problems before crews are put on them. SLS does not.
The fact that most LOVs are early in the program seems pretty obvious. The Shuttle was an exception.Every time we have one on these events my thoughts are always the same. Better now than when we have a crew on board. Pick up the pieces, find the cause(s), fix them and get flying again. Best of luck to the teams at SpaceX.
Yes, and this is exactly why I think it's so much more dangerous to put a crew on SLS than a crew on either commercial crew vehicle. Atlas V and Falcon 9 have lots of non-crew launches to find problems before crews are put on them. SLS does not.
Complete nonsense. Please show me where launching fewer times has resulted in greater chance of loss of vehicle?
The fact that most LOVs are early in the program seems pretty obvious. The Shuttle was an exception.Every time we have one on these events my thoughts are always the same. Better now than when we have a crew on board. Pick up the pieces, find the cause(s), fix them and get flying again. Best of luck to the teams at SpaceX.
Yes, and this is exactly why I think it's so much more dangerous to put a crew on SLS than a crew on either commercial crew vehicle. Atlas V and Falcon 9 have lots of non-crew launches to find problems before crews are put on them. SLS does not.
Complete nonsense. Please show me where launching fewer times has resulted in greater chance of loss of vehicle?
Quick&dirty attempt at recreating the trajectory of the fragment propelled upward -which, by the way, to me doesn't mean the explosion originated outside: it could well be a T/E panel or a torn piece of 2nd stage wall located over the failure point.
What is apparent from trying to follow it when it passes in front of the saturated fireball is that it's coming toward the camera, as it appears precisely where you would expect after it clears the brightest part of the cloud.
The last 2-3 crops show it being carried sideways to the left by the wind draft.
The fact that most LOVs are early in the program seems pretty obvious. The Shuttle was an exception.Every time we have one on these events my thoughts are always the same. Better now than when we have a crew on board. Pick up the pieces, find the cause(s), fix them and get flying again. Best of luck to the teams at SpaceX.
Yes, and this is exactly why I think it's so much more dangerous to put a crew on SLS than a crew on either commercial crew vehicle. Atlas V and Falcon 9 have lots of non-crew launches to find problems before crews are put on them. SLS does not.
Complete nonsense. Please show me where launching fewer times has resulted in greater chance of loss of vehicle?
There is a lot of talk about COPV which to me can't possibly be very high on the failure list -- my thinking follows, please set me straight on anything I'm missing:
1 - The tank was fairly full at this time, based on the extreme nature of the event and the timeline.
2 - The COPVs would be already charged, as they are not supercooled and are far harder to fill quickly
3 - The pressure differential inside and outside the COPVs was decreasing with every passing second (understanding that the differential was still extremely large)
So then, to me it seems utterly unlikely that a COPV let go while it's job was actually getting easier by the second.
Is there some counter intuitive effect with them that would make this likely or plausible?
@scrappydog yes. This seems instant from a human perspective, but it really a fast fire, not an explosion. Dragon would have been fine.
https://twitter.com/elonmusk/status/771479910778966016
The fact that most LOVs are early in the program seems pretty obvious. The Shuttle was an exception.Every time we have one on these events my thoughts are always the same. Better now than when we have a crew on board. Pick up the pieces, find the cause(s), fix them and get flying again. Best of luck to the teams at SpaceX.
Yes, and this is exactly why I think it's so much more dangerous to put a crew on SLS than a crew on either commercial crew vehicle. Atlas V and Falcon 9 have lots of non-crew launches to find problems before crews are put on them. SLS does not.
Complete nonsense. Please show me where launching fewer times has resulted in greater chance of loss of vehicle?
And Proton... and Delta II... and Taurus XL... and Soyuz...
@scrappydog yes. This seems instant from a human perspective, but it really a fast fire, not an explosion. Dragon would have been fine.
https://twitter.com/elonmusk/status/771479910778966016
Elon is say this starts as a fire not explosion, meaning starting from outside? (anything from the pressuring environment inside F9 will be an explosion)
Elon is say this starts as a fire not explosion, meaning starting from outside? (anything from the pressuring environment inside F9 will be an explosion)
If this does turn out to be the second stage again then I think that SpaceX has to ask some very difficult management questions.That is a lot of alluding.
I doubt that working on the second stage is 'sexy'. The 'sexy' things to work on will be the reusable first stage, Falcon Heavy core, Raptor and BFS/BFR.
I hate to reason from analogy and I am sure that mechanical engineering isn't as flaky as software 'engineering' but my experience suggests that trouble shooting never gets rewarded, if you solve a problem then people assume you caused it in the first place and people on the upward career path avoid projects that are associated with failure or don't deliver anything new. Even in a support team one is only judged by a contribution to delivery project. I doubt that a company with a large staff turnover will nurture staff who do what is necessary in an undramatic way.
I like to think it is a lot of iffing than alluding.If this does turn out to be the second stage again then I think that SpaceX has to ask some very difficult management questions.That is a lot of alluding.
I doubt that working on the second stage is 'sexy'. The 'sexy' things to work on will be the reusable first stage, Falcon Heavy core, Raptor and BFS/BFR.
I hate to reason from analogy and I am sure that mechanical engineering isn't as flaky as software 'engineering' but my experience suggests that trouble shooting never gets rewarded, if you solve a problem then people assume you caused it in the first place and people on the upward career path avoid projects that are associated with failure or don't deliver anything new. Even in a support team one is only judged by a contribution to delivery project. I doubt that a company with a large staff turnover will nurture staff who do what is necessary in an undramatic way.
You did a much better job than I could have done. Now, as a trajectory model, please explain how a panel from the 2nd stage gets blown to the right, then produces an arc up and to the left. :)
You clearly demonstrated the point I was trying to make, albeit, we disagree as to why. Great work!!! :)
Either way, my point was: it's not clear at all from the available footage whether the explosion originated in the vehicle or the umbilicals (and in fact, I personally lean for the former) but certainly the flying debris doesn't tell us much either way.
I'm going to speculate wildly here (Mod, please delete if inappropriate);
Point 1; The CRX7 failure occurred in the second stage.
Point 2; This explosion *appears* to have originated in the second stage.
Speculation: to my eyes, this event appears to have been highly energetic from the first moment it appears.
Further speculation; would a COPV failure (sudden release of He into the LOX) fit observations?
You are not the first person to suspect this. In my opinion, it appears consistent with overpressurization, but a problem with GSE or the valve that handles boiloff might also result in overpressurization.
The CRS-7 failure is believed to have been due to buoyant forces under several G's of loading. The buoyant forces while on the pad are far lower. Even if it was a COPV failure, I would be surprised if it was due to tank buoyancy breaking a strut.
Regardless, don't get too attached to the theory. For almost every high-visibility aerospace accident like this, there's usually half a dozen reasonable-sounding theories proposed early on. Most (sometimes all) of them turn out to be wrong.
The fact that most LOVs are early in the program seems pretty obvious. The Shuttle was an exception.Every time we have one on these events my thoughts are always the same. Better now than when we have a crew on board. Pick up the pieces, find the cause(s), fix them and get flying again. Best of luck to the teams at SpaceX.
Yes, and this is exactly why I think it's so much more dangerous to put a crew on SLS than a crew on either commercial crew vehicle. Atlas V and Falcon 9 have lots of non-crew launches to find problems before crews are put on them. SLS does not.
Complete nonsense. Please show me where launching fewer times has resulted in greater chance of loss of vehicle?
And Proton... and Delta II... and Taurus XL... and Soyuz...
Either way, my point was: it's not clear at all from the available footage whether the explosion originated in the vehicle or the umbilicals (and in fact, I personally lean for the former) but certainly the flying debris doesn't tell us much either way.
Even watching it on super-slow-mo is inconclusive. :(
As discussed upthread, the epicentre of the fireball may or may not be the source of the explosion, but if it is, the pixel at the centre of the fireball appears to correspond exactly with the LOX fuel line attachment point.Nope, that's the structural support at the common bulkhead. The umbilical attachment is lower. Look earlier in the thread for a good picture.
Just seen the video. From the flash to bang time can anyone confirm the mike was about 2.55 miles (4000 m) from the rocket?
SpaceX - Static Fire Anomaly - AMOS-6 - 09-01-2016Not really 60 FPS but the same video "slowed down" with repeating frames.
USLaunchReport - slow down & close up at 1080P 60fps
https://www.youtube.com/watch?v=XF253Gbi2S4
That sure looked like an explosion to me, rather than a fast fire. Sounded like that too.
Check the audio, there's a small pop about 5 seconds before the sound from the actual explosions arrive.
I think that's just someone messing around a car or something near the camera.
Interestingly enough, the small first bang heard is the original S2 explosion. The big bang 3 seconds later is the fuel-air type explosion when that fireball hit the ground and mixed up the RP-1 and LOX.
I hear three distinct "initial" sounds:
1:16--a very faint "plonk" like someone hitting a PVC pipe with a hammer in the distance...COPV rupture?
1:18--a faint pop/bang... S2 tank rupture?
1:23--very loud boom...the LOX/RP-1 explosion?
That first sound at 1:16 is unusual and seems to me like it may be the initiating event. A COPV or high pressure line/fitting letting go followed by S2 tank rupture 1-2 seconds later seems consistent.
And... I know the FTS is being ruled out because it would have unzipped the whole vehicle, but... that's if it was a commanded FTS. What if it's a short to the wire to the detonator in the S2 FTS det cord?
The "plonk" sounds like an empty 55-gallon drum ever so slightly expanding/contracting, there's a bit of reverb on the back-end of that sound. I'd guess it's local to the camera.
As discussed upthread, the epicentre of the fireball may or may not be the source of the explosion, but if it is, the pixel at the centre of the fireball appears to correspond exactly with the LOX umbilical attachment point.
Frustrating -- it would be useful to have seen many such explosions, but I'm sort of glad I haven't.
As discussed upthread, the epicentre of the fireball may or may not be the source of the explosion, but if it is, the pixel at the centre of the fireball appears to correspond exactly with the LOX fuel line attachment point.Nope, that's the structural support at the common bulkhead. The umbilical attachment is lower. Look earlier in the thread for a good picture.
And for everyone basing opinions on "super slow mo"---you do know that all those extra frames are made up, right? You're basing your opinion on details fabricated by an interpolation algorithm.
I find the "shape" of the detonation interesting as it has more in the horizontal than the vertical component...
Perhaps a tank dome...I find the "shape" of the detonation interesting as it has more in the horizontal than the vertical component...
Horizontal rupture rather than a vertical 'tin can'??
As discussed upthread, the epicentre of the fireball may or may not be the source of the explosion, but if it is, the pixel at the centre of the fireball appears to correspond exactly with the LOX umbilical attachment point.
Look at the debris trajectory debate I tried to start. You're about 5 meters to the left of where things started me thinks.
RP-1 tank or LOX??Perhaps a tank dome...I find the "shape" of the detonation interesting as it has more in the horizontal than the vertical component...
Horizontal rupture rather than a vertical 'tin can'??
QuoteThe "plonk" sounds like an empty 55-gallon drum ever so slightly expanding/contracting, there's a bit of reverb on the back-end of that sound. I'd guess it's local to the camera.
Or the reverb is from a high-pressure component letting go inside the S2, which is just like a very distant, oversized 55-gallon drum. ;)
RP-1 tank or LOX??Perhaps a tank dome...I find the "shape" of the detonation interesting as it has more in the horizontal than the vertical component...
Horizontal rupture rather than a vertical 'tin can'??
You beat me to it Herb! :)RP-1 tank or LOX??Perhaps a tank dome...I find the "shape" of the detonation interesting as it has more in the horizontal than the vertical component...
Horizontal rupture rather than a vertical 'tin can'??
Common bulkhead between the two perhaps.
Personally, I think this is what happened in the in-flight failure as well, but I lack the data to make the argument persuasive. This time, SpaceX may be able to recover sufficient debris to make a determination.
RP-1 tank or LOX??Perhaps a tank dome...I find the "shape" of the detonation interesting as it has more in the horizontal than the vertical component...
Horizontal rupture rather than a vertical 'tin can'??
Common bulkhead between the two perhaps.
T-0:04:10 Strongback Cradles Opening
T-0:03:30 Strongback Retraction
I'd think that if stage 2 overpressurized we'd have heard something along those lines somewhere, that's the kind of reading SpaceX would definitely have quite shortly after the event.
QuoteAnd... I know the FTS is being ruled out because it would have unzipped the whole vehicle, but... that's if it was a commanded FTS. What if it's a short to the wire to the detonator in the S2 FTS det cord?
Once again, not possible. The safe/arm device which contains the FTS detonator typically has both mechanical and electrical inhibits to accidental initiation in the "safe" position. FTS was safed at the time of the accident.
You could take a hammer and a 12 volt car battery to pretty much any aerospace qualified FTS safe/arm device, and as long as it's in the "safe" position, not be able to set off the detonator after an hour of beating/zapping it.
QuoteAnd... I know the FTS is being ruled out because it would have unzipped the whole vehicle, but... that's if it was a commanded FTS. What if it's a short to the wire to the detonator in the S2 FTS det cord?
Once again, not possible. The safe/arm device which contains the FTS detonator typically has both mechanical and electrical inhibits to accidental initiation in the "safe" position. FTS was safed at the time of the accident.
You could take a hammer and a 12 volt car battery to pretty much any aerospace qualified FTS safe/arm device, and as long as it's in the "safe" position, not be able to set off the detonator after an hour of beating/zapping it.
IMHO, we need to be clear here; there's a difference between the detonators and the explosive. The explosive itself is quite safe; you can toss a chunk into a fire with no ill effect (or whack it with a hammer, etc). That's why you safe explosive egress systems on military aircraft by taking out the detonators, not the explosives. The explosive itself (with no detonator present) is pretty much inert, and about as dangerous as a similar sized chunk of wax (unless exposed to very high temperatures/pressures such as from a high-order explosion, usually provided by a detonator).
Detonators, on the other hand, are very twitchy beasts. Hitting one with a hammer is not a good idea.
What this means in practice is that if the detonators were installed, accidental initiation via static charge or electrical fault is possible. If they are physically not in the det cord, it's pretty much impossible. If the detonators are not installed for a static fire, what I postulated is impossible. If the mechanical safing you mention involves physically removing the detonators, and that was in effect, what I postulated is impossible. However, if the detonators were physically present in the det cord, then what I postulated is not impossible (though still very unlikely) no matter what safeguards there are.
To be clear, I'm not taking about an accidentally commanded FTS initiation, but an electrostatic event caused by a ground leader event (also called a step leader, and more than enough to kill a human) triggering a single detonator (I know them monitor the field density as part of the launch criteria, but do those apply for a static fire?). I think this scenario very unlikely, but possible, if and only if the location of the det cord is in the area the explosion was first seen. (Caveat: this scenario is also impossible sans significant electrostatic buildup).
For those curious on what a step leader is, here's a link;
http://www.lightningsafety.noaa.gov/science/science_initiation_stepped_leader.htm
It definitely starts with a bright flash, then decreases in brightness for a few frames, then increases again.
Yes, and what I'm saying is that the detonator is typically *inside* the safe/arm device, which has both electrical and mechanical inhibits. The safe/arm device is designed to be shock resistant, so you can beat on it with a hammer and zap it with current and still not be able to set off the detonator inside, when the device is "safed."
Yes, and what I'm saying is that the detonator is typically *inside* the safe/arm device, which has both electrical and mechanical inhibits. The safe/arm device is designed to be shock resistant, so you can beat on it with a hammer and zap it with current and still not be able to set off the detonator inside, when the device is "safed."
If that device includes some way of 100% isolating the detonators from an electrical surge of a magnitude inherent in a step leader (on the order of tens of thousands of volts), then what I'm postulating is impossible.
Yes, and what I'm saying is that the detonator is typically *inside* the safe/arm device, which has both electrical and mechanical inhibits. The safe/arm device is designed to be shock resistant, so you can beat on it with a hammer and zap it with current and still not be able to set off the detonator inside, when the device is "safed."
If that device includes some way of 100% isolating the detonators from an electrical surge of a magnitude inherent in a step leader (on the order of tens of thousands of volts), then what I'm postulating is impossible.
Once again, it's not just a matter of electrical inhibits/isolation. Typically there is also a *mechanical barrier* between detonator and main charge that prevents shock wave transmission in the "safe" condition.
Yes, and what I'm saying is that the detonator is typically *inside* the safe/arm device, which has both electrical and mechanical inhibits. The safe/arm device is designed to be shock resistant, so you can beat on it with a hammer and zap it with current and still not be able to set off the detonator inside, when the device is "safed."
If that device includes some way of 100% isolating the detonators from an electrical surge of a magnitude inherent in a step leader (on the order of tens of thousands of volts), then what I'm postulating is impossible.
Once again, it's not just a matter of electrical inhibits/isolation. Typically there is also a *mechanical barrier* between detonator and main charge that prevents shock wave transmission in the "safe" condition.
Yes, and what I'm saying is that the detonator is typically *inside* the safe/arm device, which has both electrical and mechanical inhibits. The safe/arm device is designed to be shock resistant, so you can beat on it with a hammer and zap it with current and still not be able to set off the detonator inside, when the device is "safed."
If that device includes some way of 100% isolating the detonators from an electrical surge of a magnitude inherent in a step leader (on the order of tens of thousands of volts), then what I'm postulating is impossible.
Once again, it's not just a matter of electrical inhibits/isolation. Typically there is also a *mechanical barrier* between detonator and main charge that prevents shock wave transmission in the "safe" condition.
AH! My apologies, I misunderstood. I thought that was for safing the system manually, not remotely changeable on the pad. I stand corrected.
here's a link to the last launch count down. gives a look at where the umbilicals and such are
https://www.youtube.com/watch?v=OERDIFnFvHs?t=13m29s
Just impressions from watching the video at regular speed. The piece of flying debris that's been talked about looks like it bounced off the tower rather than originating from it. And the tower was deformed by the weight of the payload and fairing sitting on the cradle arms, suddenly without the support of the rocket structure.
Guess I'm not adding much. What a crappy day. The repercussions (so to speak) are going to be huge. Sad.
You did a much better job than I could have done. Now, as a trajectory model, please explain how a panel from the 2nd stage gets blown to the right, then produces an arc up and to the left. :)
You clearly demonstrated the point I was trying to make, albeit, we disagree as to why. Great work!!! :)
Thanks, but I stand by my interpretation (and in fact I would like to know what your proposed mechanism for the trajectory is if the debris is blown from the T/E side)
The trajectory can easily be identified as coming from the rocket as follows:
If the failure point on S2 was ~45º to the right of the line joining the F9 and the camera, and we assume an upper part of the S2 LOX tank wall was blown outward from an interior event, to then hinge on its upper section for a few milliseconds, until being ripped off the structure by the expanding cloud of oxidizer, centrifugal forces would blow it upward (and it would rotate along the axis parallel to the "hinge"). Further, if the "hinge" was at an angle with respect to the ground, or if hinge failure/departure from the rest of the stage happened before it reached a 180º pivoting, some of the centrifugal force would be propelling it toward the camera. This, plus a bit of wind drag pushing the piece to the left (the "vertical" trip is about 3x faster than the time period around the upper section of the arc) could perfectly explain the trajectory we see.
Or, it could just be a piece from the T/E that was blown off from the overpressure.
Either way, my point was: it's not clear at all from the available footage whether the explosion originated in the vehicle or the umbilicals (and in fact, I personally lean for the former) but certainly the flying debris doesn't tell us much either way.
Apparently not having learned not to speculate, I submit that the following fits what we can observe: that the umbilical connection partially disconnected. This could possibly cause aerosolization of RP-1 (like a finger almost fully closing a garden hose), and such aerosolization seems a requirement to explain the initial flash. It's also consistent with the subsequent downward-pointing flame (some of the RP-1 being aerosolized, but lots of it just dripping).
Here's what a typical safe/arm device looks like. The silver flex line coming out of the top is the explosive train leading to the main FTS charge.
http://www.eba-d.com/products/electro-mechanical-safe-arm-sa-device/
One electrical connector receives commands to rotate the internal detonator(s) between the safe and armed positions. The other connector receives the "fire" command to set off the detonator.
Usually the safe/arm commands can be sent to it either through ground lines during static fire tests or actual launches, or via flight computer autonomously for in-flight arming/safing.
correct as they were in the Stage 2 LOX loading steps of the static test countdown at the time of the event(s).Apparently not having learned not to speculate, I submit that the following fits what we can observe: that the umbilical connection partially disconnected. This could possibly cause aerosolization of RP-1 (like a finger almost fully closing a garden hose), and such aerosolization seems a requirement to explain the initial flash. It's also consistent with the subsequent downward-pointing flame (some of the RP-1 being aerosolized, but lots of it just dripping).
RP-1 was already loaded. There would not be any pressure in that part of the umbilical.
Just impressions from watching the video at regular speed. The piece of flying debris that's been talked about looks like it bounced off the tower rather than originating from it. And the tower was deformed by the weight of the payload and fairing sitting on the cradle arms, suddenly without the support of the rocket structure.
Guess I'm not adding much. What a crappy day. The repercussions (so to speak) are going to be huge. Sad.
The trajectory has that part going a few hundred yards off the bounce point in your theory. Other than super balls, most materials will crumple on impact rather than bounce. I don't buy the bounce idea, but... maybe it is a superball. If you look at the part as it tumbles, it seems to be a "cap" to something. Are there "cap" structures on the strongback?
Just impressions from watching the video at regular speed. The piece of flying debris that's been talked about looks like it bounced off the tower rather than originating from it. And the tower was deformed by the weight of the payload and fairing sitting on the cradle arms, suddenly without the support of the rocket structure.
Guess I'm not adding much. What a crappy day. The repercussions (so to speak) are going to be huge. Sad.
The trajectory has that part going a few hundred yards off the bounce point in your theory. Other than super balls, most materials will crumple on impact rather than bounce. I don't buy the bounce idea, but... maybe it is a superball. If you look at the part as it tumbles, it seems to be a "cap" to something. Are there "cap" structures on the strongback?
Not a theory, just an impression as I said. Caveat: the scotch kicked in a couple hours ago.
"A few hundred yards" seems just as speculative. But strong dense objects can do amazing things when propelled at high velocities in energetic events.
Slightly off topic question. A helicopter could be heard later in the video. Presumably this is from the airbase. Was it in the air at the time or did they scramble it after the explosion?
The thing about all the LOX overpressure speculation is that we know what that looks like -- it starts to puff out in big streams from the lox vents. That wasn't happening. There was no apparent change in the LOX venting in the seconds prior to the explosion.
As for seeing LOX vent spikes, that's normal. I've seen that in the launches many times, right before the strongback was retracted. I think it has to do with blowing out the fill lines, or something. But again, I didn't see any LOX vent spikes within, say, five to ten seconds prior to the blast.
Whatever happened, I don't think it was the LOX tank overpressurizing in stage 2...
It definitely starts with a bright flash, then decreases in brightness for a few frames, then increases again.
Looking at the leftmost tower, the initial flash does not illuminate it, but once the fireball is bigger than the rocket it's illuminated as well.
time for a lessons learned?
Maybe dropping the trunk is a good idea now?
Whatever happened, I don't think it was the LOX tank overpressurizing in stage 2...
The event is so sudden, instantaneous really, that it makes me think the most likely cause is failure of the common bulkhead with instant mixing of the LOX and kero. What is the pressure differential between the tanks?
The event is so sudden, instantaneous really, that it makes me think the most likely cause is failure of the common bulkhead with instant mixing of the LOX and kero. What is the pressure differential between the tanks?
time for a lessons learned?
Maybe dropping the trunk is a good idea now?
What lesson? The trunk is required for passive aerodynamic stability after SD's stop firing, while the stack is coasting up to apogee. Without the trunk, the capsule will tumble immediately after SD's stop firing, with unpleasant consequences for passengers.
The event is so sudden, instantaneous really, that it makes me think the most likely cause is failure of the common bulkhead with instant mixing of the LOX and kero. What is the pressure differential between the tanks?
That wouldn't cause a bang in and of itself - there'd first be a spray of stuff outward like we saw with the S2 launch failure. This time the 'bang' seems to happen first.
From the location of the umbilical, can I assume that the fuel goes directly to the tank, while the LOX pipe runs through or around the fuel tank. If there is a leak in this pipe, an explosive mixture could build up and then go off suddenly, causing a flash and then a tank breech.
The event is so sudden, instantaneous really, that it makes me think the most likely cause is failure of the common bulkhead with instant mixing of the LOX and kero. What is the pressure differential between the tanks?
That wouldn't cause a bang in and of itself - there'd first be a spray of stuff outward like we saw with the S2 launch failure. This time the 'bang' seems to happen first.
In CRS-7 it appeared that the LOX tank ruptured at the top rather than at the common bulkhead. If the Common bulkhead ruptures we won't see it right away but allows the fuel to mix to setup a scenario for a kaboom. Then there just has to be an ignition source.
If we have a "graphics wiz" that can superimpose a Falcon cutaway over a video still, that would be great! :)
Is the decision to have the payload attached our not attached during a static fire at the discretion of the customer?
I was looking back at static fire video and JCSAT-14,16 no payload attached and the same with EUTELSAT-ABS.
However Thaicom-8 payload was attached. Also for CRS-8, CRS-9 Dragon was attached.
SpaceX really dodged a bullet that this didn't happen on CRS-9.
The event is so sudden, instantaneous really, that it makes me think the most likely cause is failure of the common bulkhead with instant mixing of the LOX and kero. What is the pressure differential between the tanks?
That wouldn't cause a bang in and of itself - there'd first be a spray of stuff outward like we saw with the S2 launch failure. This time the 'bang' seems to happen first.
In CRS-7 it appeared that the LOX tank ruptured at the top rather than at the common bulkhead. If the Common bulkhead ruptures we won't see it right away but allows the fuel to mix to setup a scenario for a kaboom. Then there just has to be an ignition source.
Electric signal and power wires could be sheared by a bulkhead that fails catastrophically under pressure? The liquid forms a short across suddenly exposed lines of different potential.
In some ways I hope for SpaceX's case that is was some sort of subtle vehicle failure--one they can catch and design-out, not a GSE failure. The reason I say this is that the last time a US rocket blew up on the pad without an engine failure of some sort was over half a century ago. There've been well over 1000, and possibly over 2000 liquid fueled rocket launches since then, without any of them blowing up on the pad due to GSE issues. So having a pad systems failure actually makes SpaceX look a lot less professional than if it was a subtle design flaw.
On the what actually happened, it still really looks like the failure started inside the stage, not an external explosion that happened to rupture the tanks. That's not objective fact, and I may be misreading it, but that's what it looked like from the video. I just don't see some sort of "both umbilicals leaked in just the right way to also catch a spark" sort of scenario as being realistic. It's wild speculation, but I still think something to do with the common bulkhead did it.
People keep pointing out that it didn't look like the CRS-7 overpressurization, but that was a much slower event caused by a tube breaking, which meant you would've had choked flow out of a small diameter line. If you had a more rapid overpressurization event, it might look totally differently. A COPV failing more dramatically for instance might happen much. much faster, especially if it ruptured the common bulkhead. If say a dome came off of a COPV, it would probably be going fast enough that the whole bulkhead would be ruptured in less than one frame of the video. And the energy from that sort of a failure would not only mix the propellants, but could also quite possibly ignite the mixed propellants.
My Rambling $.02
~Jon
The event is so sudden, instantaneous really, that it makes me think the most likely cause is failure of the common bulkhead with instant mixing of the LOX and kero. What is the pressure differential between the tanks?
That wouldn't cause a bang in and of itself - there'd first be a spray of stuff outward like we saw with the S2 launch failure. This time the 'bang' seems to happen first.
In CRS-7 it appeared that the LOX tank ruptured at the top rather than at the common bulkhead. If the Common bulkhead ruptures we won't see it right away but allows the fuel to mix to setup a scenario for a kaboom. Then there just has to be an ignition source.
Electric signal and power wires could be sheared by a bulkhead that fails catastrophically under pressure? The liquid forms a short across suddenly exposed lines of different potential.
There is very little wiring inside the tanks and nothing would run through the common bulkhead. But I agree that once you have a massive failure like that there are lots of moving parts (that shouldn't be) and the potential of something producing a spark is much greater.
Conduits outside the tanks and maybe electrical interfaces with the t/e. Conductive liquids, flying metal and sheared wires...
Conduits outside the tanks and maybe electrical interfaces with the t/e. Conductive liquids, flying metal and sheared wires...
The liquids in this case are non-conductive and hundreds of degrees F below ignition point. No, I'm sticking with Jon's idea that a COPV failure or some similar plumbing failure inside the stage itself triggered the bulge pointed out several pages upthread. :)
Elon already confirmed the problem was in the S2 O2 tank, that is not in question.
All good thoughts. Only problem is, repercussions from a COPV failure (ie major redesign) are going to be a lot more painful for them than a simple GSE issue. So I'm going to take the other side and hope it was in fact a GSE issue.
Conduits outside the tanks and maybe electrical interfaces with the t/e. Conductive liquids, flying metal and sheared wires...
The liquids in this case are non-conductive and hundreds of degrees F below ignition point. No, I'm sticking with Jon's idea that a COPV failure or some similar plumbing failure inside the stage itself triggered the bulge pointed out several pages upthread. :)
O2 overpressure alone doesn't make a kaboom, just a pop. There has to be a mixing of fuels an an ignition source in order to cause an explosive boom like we saw. That is what we are trying to explain. Elon already confirmed the problem was in the S2 O2 tank, that is not in question.
Some of the media stories about the incident are totally pathetic and inaccurate. Drives me crazy!
Totally true, they just take some random journalist and get them on the story, even if they have never heard of SpaceX before.Some of the media stories about the incident are totally pathetic and inaccurate. Drives me crazy!
Let's put it this way.. they know less they we do and aren't paid to get their facts right - just to get the story out there before the next guy.
I find them amusing. :)
Conduits outside the tanks and maybe electrical interfaces with the t/e. Conductive liquids, flying metal and sheared wires...
The liquids in this case are non-conductive and hundreds of degrees F below ignition point. No, I'm sticking with Jon's idea that a COPV failure or some similar plumbing failure inside the stage itself triggered the bulge pointed out several pages upthread. :)
O2 overpressure alone doesn't make a kaboom, just a pop. There has to be a mixing of fuels an an ignition source in order to cause an explosive boom like we saw. That is what we are trying to explain. Elon already confirmed the problem was in the S2 O2 tank, that is not in question.
That's the thing, rapidly shearing metal and exposing fresh, unoxidized aluminum or titanium (if they have any in the tanks) may be able to release enough energy to set off a LOX/Kero mix without a separate ignition source.
Thank you, you're still a "wiz" in my books! :) It pretty much confirms my estimation of the location of common bulkhead that may have failed. The area would possibly lead to a "pseudo" horizontally shaped detonation cloud with more energy directed in this direction than vertically.If we have a "graphics wiz" that can superimpose a Falcon cutaway over a video still, that would be great! :)
I'm hardly a 'graphics wiz', but it looks like the epicentre is adjacent the common bulkhead.
It seemed like a really quick response time but I just noticed an edit in the video around 3:32 so there could have been much more time between explosion and response. More likely medics than the air force then.Slightly off topic question. A helicopter could be heard later in the video. Presumably this is from the airbase. Was it in the air at the time or did they scramble it after the explosion?
someone said earlier there was a medvac helicopter that picked up someone with the fire department to scout out the fire. long distance video from the vab showed a heli pretty close to the pad. not sure if its the same as you are hearing.
An additional element was added for Wednesday’s test, per L2 info (https://forum.nasaspaceflight.com/index.php?topic=40768.msg1567989#msg1567989), with a couple of holds added ahead of the terminal count to demonstrate performance during simulated window extensions.
Due to Falcon 9 now using super cooled propellent [sic], holds after prop loading begins around T-30 minutes provide an additional challenge of keeping the prop cold enough in the run up to T-0.
Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
Twitter User TJ Lee did an interesting video edit here, superimposing the Dragon abort test over the video of today's accident:
https://twitter.com/StateMachines/status/771535425328459780
Dragon would have had plenty of time to escape.
time for a lessons learned?IMO no it isn't because D2 needs the trunk for aerodynamic stability during abort. If the trunk is not there the entire aerodynamic shape of D2 will have to be altered or some other means of stability will have to be added to the design. Given that the trunk is mostly an empty shell it should not be too hard to "harden" it against over-pressure events coming from below. Given that the trunk has been in the design particularly for pad abort, I thinks it is pretty safe to conclude that the D2 trunk design already is optimised for over-pressure events from below. We also know that the trunk-to-capsule interface is hardened with a wipple-shield. That serves dual purposes:
<snip>
Maybe dropping the trunk is a good idea now?
Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
Some of the media stories about the incident are totally pathetic and inaccurate. Drives me crazy!
Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
If we assume the event originated in the second stage, as it appears to do, I find it interesting that both of SpaceX's LOV/LOM events originated in the second stage, and did so while that stage's engine was not running.
Could be just a coincidence - and I don't like coincidences.
Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
It definitely looks like it's some sort of fuel line, but the part we see looks like a housing, rather than a naked pipe. There's cabling of some sort that is in nearly direct contact with the second stage at the approximate center of the diffraction lines as well. If leaking fuel lines were an issue, the pending inclement weather may have exacerbated some sort of ground fault.
Twitter User TJ Lee did an interesting video edit here, superimposing the Dragon abort test over the video of today's accident:
https://twitter.com/StateMachines/status/771535425328459780
Dragon would have had plenty of time to escape.
This is very interesting (assuming frame rates are matched exactly)! I wonder what the lag would be though? Surely this is best case. What trigger would the F9 systems have to detect a problem and launch the Dragon V2 abort that quickly? (speculation) If the 'explosion' does happen to be something like a fast-fire external to the rocket, would the rocket even be able to tell something was wrong before the damaging explosions happen?
Over on the Facebook SpaceX group user Ross Sackett posted this photo with the following caption:
"I used a trick we sometimes use to fix the position of a star in an astrophoto. While the fireball is burned into the image making it hard to locate the center, the lens flares (probably diffraction spikes) are centered on the brightest part. Make of this what you will."
All credit for image and words to Facebook user Ross Sackett
I don't have a video editor so these are just screen grabs. Is there any frames in between?
Note the bird passing the lightning tower, I used that to compare frames.
Can anybody assign time to this in terms of T-x minutes?
I don't have a video editor so these are just screen grabs. Is there any frames in between?
Note the bird passing the lightning tower, I used that to compare frames.
Can anybody assign time to this in terms of T-x minutes?
Not sure about the frame question, but I do believe F9 was at approximately T-3:00 to ignition.
I don't have a video editor so these are just screen grabs. Is there any frames in between?
Note the bird passing the lightning tower, I used that to compare frames.
Can anybody assign time to this in terms of T-x minutes?
Not sure about the frame question, but I do believe F9 was at approximately T-3:00 to ignition.
If we assume the event originated in the second stage, as it appears to do, I find it interesting that both of SpaceX's LOV/LOM events originated in the second stage, and did so while that stage's engine was not running.
Could be just a coincidence - and I don't like coincidences.
There are two stages. Let's say chances of a problem in any particular are 50:50, or 1/2. That means the chances of something happening twice in the same stage are 1/4. ie one in four. That a much higher chance of happening in the same stage than throwing 2 sixes in a row.
It's a coincidence until shown otherwise.
So much jumping to conclusions here, without really thinking about the issue.
Space is hard.
Space is hard.
Space is not just hard, it's very unforgiving.
Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
Just playing devil's advocate here. I agree with the airburst, but how about a crack or a pinhole in the rocket itself as the source? Is there anything that would preclude that or make one more likely than the other? (I'm half wondering whether the supercooled oxygen might be causing more damage to the GSE side of things than people imagine - though I counter that with the necessity for fuel in the explosion)
Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
Just impressions from watching the video at regular speed. The piece of flying debris that's been talked about looks like it bounced off the tower rather than originating from it. And the tower was deformed by the weight of the payload and fairing sitting on the cradle arms, suddenly without the support of the rocket structure.
Guess I'm not adding much. What a crappy day. The repercussions (so to speak) are going to be huge. Sad.
The trajectory has that part going a few hundred yards off the bounce point in your theory. Other than super balls, most materials will crumple on impact rather than bounce. I don't buy the bounce idea, but... maybe it is a superball. If you look at the part as it tumbles, it seems to be a "cap" to something. Are there "cap" structures on the strongback?
Not a theory, just an impression as I said. Caveat: the scotch kicked in a couple hours ago.
"A few hundred yards" seems just as speculative. But strong dense objects can do amazing things when propelled at high velocities in energetic events.
Ya, you're right. There's only data for the horizontal travel distance, not the to camera distance. When it crosses the tower, it's moved at least 50 yards from the explosion center. How far towards the camera is speculative.
I believe earlier info says it's the customer's decision. CRS flights are attached because it's SpaceX's ship, and they decide to do it that way, for both mating and testing reasons (helps build confidence in attachments, resonance modes, electrical systems, etc).
Customers are generally given the choice between having their payload on during the static fire, which speeds up the timeline a bit and gives better test data, or not having it attached, which means the payload won't be damaged in the event of an anomaly.
I personally hope SpaceX and its customers continue to mate prior to static firing. The chance of the type of anomaly seen today occurring is low, even before taking into account the fact that SpaceX will be taking a long, hard look at every inch of these systems in the next 6 months. Choosing to give up test data because of such a slim chance seems a waste to me, but then again, it depends on whether your "launch insurance" is also "integration and testing insurance".
I believe earlier info says it's the customer's decision. CRS flights are attached because it's SpaceX's ship, and they decide to do it that way, for both mating and testing reasons (helps build confidence in attachments, resonance modes, electrical systems, etc).
Customers are generally given the choice between having their payload on during the static fire, which speeds up the timeline a bit and gives better test data, or not having it attached, which means the payload won't be damaged in the event of an anomaly.
I personally hope SpaceX and its customers continue to mate prior to static firing. The chance of the type of anomaly seen today occurring is low, even before taking into account the fact that SpaceX will be taking a long, hard look at every inch of these systems in the next 6 months. Choosing to give up test data because of such a slim chance seems a waste to me, but then again, it depends on whether your "launch insurance" is also "integration and testing insurance".
If we have a "graphics wiz" that can superimpose a Falcon cutaway over a video still, that would be great! :)
I'm hardly a 'graphics wiz', but it looks like the epicentre is adjacent the common bulkhead.
1. Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
2. Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
Also not a graphics wiz
:)
Ya, you're right. There's only data for the horizontal travel distance, not the to camera distance. When it crosses the tower, it's moved at least 50 yards from the explosion center. How far towards the camera is speculative.
I don't have an easy way to d/l the video and no software to analyze it; but if the angular "diameter" of the part can be measured, the angular diameter is inversely proportional to the distance. I.e., if it looks twice the size in the last frame as compared to the first frame, it's half as far away in the last frame as it was in the first frame.
It's tempting to want to do a kinematic analysis of the part's flight, but I'd not trust the timestamps on a downloaded file that had been compressed for Youtube any farther than I could kick the bits in the file. You could get the initial vertical velocity and see if friction was important (which depends on the mass/area ratio) but not sure that would give any useful info.
Probably something similar to the escape system on the Saturn series. I believe 3-4 continuous lines were strung along the outside of the rocket, with escape being triggered the moment that one of those wires were broken. Extraordinarily simple circuit that worked surprisingly well. I'm sure SpaceX's avionics have access to a vastly more granular and detailed array of data from which to decide, ranging from pressure sensors to stress, acoustic, tensile, and more. So similar concept but far less likely to experience false-positive or false-negative events.
I believe earlier info says it's the customer's decision. CRS flights are attached because it's SpaceX's ship, and they decide to do it that way, for both mating and testing reasons (helps build confidence in attachments, resonance modes, electrical systems, etc).
Customers are generally given the choice between having their payload on during the static fire, which speeds up the timeline a bit and gives better test data, or not having it attached, which means the payload won't be damaged in the event of an anomaly.
I personally hope SpaceX and its customers continue to mate prior to static firing. The chance of the type of anomaly seen today occurring is low, even before taking into account the fact that SpaceX will be taking a long, hard look at every inch of these systems in the next 6 months. Choosing to give up test data because of such a slim chance seems a waste to me, but then again, it depends on whether your "launch insurance" is also "integration and testing insurance".
There is no valid test data that can be gained by having the spacecraft on the vehicle during static fire. It is only a time saving measure.
I don't have an easy way to d/l the video and no software to analyze it; but if the angular "diameter" of the part can be measured, the angular diameter is inversely proportional to the distance. I.e., if it looks twice the size in the last frame as compared to the first frame, it's half as far away in the last frame as it was in the first frame.
That's a good idea, but the imaging doesn't support it. The order is from 1:11 to 1:14 in the video. The lighting levels and background levels are swinging wildly. While the object is coming towards the camera, the illumination either obscures parts, the orientation of the object shifts to narrow end towards camera, or it breaks up while inside the fireball.
...I can't imagine even extensive repairs would pose a time constraint on future launches given the comparatively "benign" fuel involved in the event (no toxic solid fuel residue). ...
Are there any reliable (if not official) reports on the condition of the pad and GSE? Not speculation based on videos. I can't imagine even extensive repairs would pose a time constraint on future launches given the comparatively "benign" fuel involved in the event (no toxic solid fuel residue). Still, it would be nice to know the extent of the repairs necessary.After they do a survey they will still have to take in the environmental impact for the clean up procedures and to contain any residue from the combustion products. The firefighters more than likely have placed booms and berms either yesterday or today.
Somewhere in the volumes of written word from the last 24 hours, there was the phrase from SpaceX, "Catastrophic abort."
Probably something similar to the escape system on the Saturn series. I believe 3-4 continuous lines were strung along the outside of the rocket, with escape being triggered the moment that one of those wires were broken. Extraordinarily simple circuit that worked surprisingly well. I'm sure SpaceX's avionics have access to a vastly more granular and detailed array of data from which to decide, ranging from pressure sensors to stress, acoustic, tensile, and more. So similar concept but far less likely to experience false-positive or false-negative events.
No, again, most data goes overboard as telemetry and vehicle avionics doesn't see it. Abort systems pick a few critical parameters (like tank pressures, breakwires, engine temps, etc) and just monitor them. "Stress, acoustic, tensile, and more" are foreign to launch vehicle control avionics.
1. Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
2. Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
1. It is an air burst because of a rupture. Rupture came first.
2. That would be an AC line. The second stage umbilical is lower
SpaceX decided to immerse their COPVs in their propellant. Given that choice, why did they choose to immerse them in the LOX, which is nasty stuff both chemically and thermally, instead of in the comparatively benign RP1?It's colder, and He expansion per J/kg is the highest of any element, basically, they can increase density by 20x "for free".
Also as a gas is compressed it get hot. Depending on the fill rate you could end up creating bubbles of RP1 vapor or start to polymerize it into a tarry mix.In the LOX tank you make O2 bubbles which vent (usually) harmlessly and top up with more LOX.SpaceX decided to immerse their COPVs in their propellant. Given that choice, why did they choose to immerse them in the LOX, which is nasty stuff both chemically and thermally, instead of in the comparatively benign RP1?It's colder, and He expansion per J/kg is the highest of any element, basically, they can increase density by 20x "for free".
Can you explain how a rupture does that please?
Keep in mind there is an entire half of the rocket that is not visible in this video. Who knows what was happening on the far side of the rocket moments before it detonated?1. Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
2. Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
1. It is an air burst because of a rupture. Rupture came first.
2. That would be an AC line. The second stage umbilical is lower
Just to debate the idea that the rupture came first. Based on the detonation profile that implies a fuel-air explosion, the absence of any visible plume changes prior to the explosion 1st frame, an oxygen tank rupture would create a plume, and would not itself cause a detonation. An RP-1 rupture might not show a plume but would provide the material needed for a fuel-air explosion. If there were an RP-1 rupture, how would that occur?
We go from one frame where there is no indication of abnormal plumes to a frame where the detonation is about 35 X 85 feet across. In 1/60th of a second you have to fill that volume with RP-1 aerosol (not liquid) and it has to explode during that same window.
Can you explain how a rupture does that please?
Ya, you're right. There's only data for the horizontal travel distance, not the to camera distance. When it crosses the tower, it's moved at least 50 yards from the explosion center. How far towards the camera is speculative.
Can you explain how a rupture does that please?
That is the only way the propellants became available to burn
Do you know where the 2nd stage RP1 lines are on the strong back? Knowing that could help localize whether the detonation is consistent with their position, or not. i.e. a fuel line problem is another source.
Do you know where the 2nd stage RP1 lines are on the strong back? Knowing that could help localize whether the detonation is consistent with their position, or not. i.e. a fuel line problem is another source.
There is no RP-1 flowing at that time.
RP-1 lines are at the bottom of the stage
Do you know where the 2nd stage RP1 lines are on the strong back? Knowing that could help localize whether the detonation is consistent with their position, or not. i.e. a fuel line problem is another source.
There is no RP-1 flowing at that time.
RP-1 lines are at the bottom of the stage
Do you know where the 2nd stage RP1 lines are on the strong back? Knowing that could help localize whether the detonation is consistent with their position, or not. i.e. a fuel line problem is another source.
There is no RP-1 flowing at that time.
RP-1 lines are at the bottom of the stage
lot of discussion about what is where on the tower in relation to the explosion.
this wired article has a couple of closeups of the tower and stage in the area you guys are talking about. Older Falcon variant i think, but i doubt the geometry has changed much
http://www.wired.com/2012/05/the-launch-pad-spacex-falcon-9-ready-for-liftoff/
also here's a hi res closeup i found linked off reddit of interstage area, a little lower down, good view of the service lines on the tower
http://i.imgur.com/7LL2HUp.jpg
bottom line - unless i'm looking at the images wrong, there isn't much beyond ECS (AC) and power running up past the lower part of the 2nd stage.
It wouldn't have to be flowing. Only leaking during fueling.
Well, what happens in the lines when propellants are not flowing? Are they still filled with propellants? Are they pressurized? Is there air in the fuel line?
Wups, Saab beat me to it.
Are there any other cases where there has been a complete loss of launch vehicle and payload days before T-0?As well as the Russian incidents that have already been mentioned, there was a relatively recent fatal incident of this type in Brazil; https://en.wikipedia.org/wiki/VLS-1_V03
It wouldn't have to be flowing. Only leaking during fueling.
And that would be seen and they would not have completed the tanking
Curious, anyone know what kind of refrigerant gets used for the fairing's AC? I know a lot of big commercial air chillers use ammonia, which if there is a leak in the system can make a pretty flammable concoction...None, they use air to create a positive pressure inside the fairing. What you're thinking is cooling while the AC is used to maintain a clean environment.
There have been lots of posts about the possibility of a leak outside the vehicle catching fire, (far to many to know which one to quote)
Curious, anyone know what kind of refrigerant gets used for the fairing's AC? I know a lot of big commercial air chillers use ammonia, which if there is a leak in the system can make a pretty flammable concoction...None, they use air to create a positive pressure inside the fairing. What you're thinking is cooling while the AC is used to maintain a clean environment.
Yes, passive air cooling and I was not 100% certain if they did a air/GN2 change-over for the PLF purge.Curious, anyone know what kind of refrigerant gets used for the fairing's AC? I know a lot of big commercial air chillers use ammonia, which if there is a leak in the system can make a pretty flammable concoction...None, they use air to create a positive pressure inside the fairing. What you're thinking is cooling while the AC is used to maintain a clean environment.
The air is also cooled along with being filtered. But at that point in the countdown, it should be GN2
JCM how do you classify this event? A payload and rocket were lost at the launch pad but it wasn't a launch failure as it wasn't a launch attempt. Watching your website to see how you classify it as it is probably the launch log of choice on the web
JCM how do you classify this event? A payload and rocket were lost at the launch pad but it wasn't a launch failure as it wasn't a launch attempt. Watching your website to see how you classify it as it is probably the launch log of choice on the web
I'm not JCM, but do my own tracking of launches. Even though the payload was lost in a prelaunch exercise, it counts as a failure in my book. You don't necessarily have to distinguish between a launch failure or a ground failure. But it's a fact that the vehicle failed to get the payload to orbit. It's not like the vehicle failed without the payload and you just get a new booster and have a successful mission a few months later.
Yeah, that's how I've got it in my SpaceX launches spreadsheet.JCM how do you classify this event? A payload and rocket were lost at the launch pad but it wasn't a launch failure as it wasn't a launch attempt. Watching your website to see how you classify it as it is probably the launch log of choice on the web
I'm not JCM, but do my own tracking of launches. Even though the payload was lost in a prelaunch exercise, it counts as a failure in my book. You don't necessarily have to distinguish between a launch failure or a ground failure. But it's a fact that the vehicle failed to get the payload to orbit. It's not like the vehicle failed without the payload and you just get a new booster and have a successful mission a few months later.
Two things bother me greatly.
1. The onset speed of the detonation.
2. The trajectory of that "thingee" that flies over the plume apparently from the strongback.
SpaceX decided to immerse their COPVs in their propellant. Given that choice, why did they choose to immerse them in the LOX, which is nasty stuff both chemically and thermally, instead of in the comparatively benign RP1?
Question: if we assume for a moment that the vehicle is intact and the fuel is coming from a leak outside the vehicle: would a fuel air mixture burning in open air breach the oxygen tanks? We know it makes for a nice fireball but as explained earlier it is not a bomb just a fire (to use laymen's terms for detonation vs deflagration).
So would a burning fuel/air mixture outside the vehicle rupture the vehicle tanks from the outside? or just burn to depletion?
Well, what happens in the lines when propellants are not flowing? Are they still filled with propellants? Are they pressurized? Is there air in the fuel line?
Wups, Saab beat me to it.
Standard practice would be to not to hold pressure after loading
Two things bother me greatly.
1. The onset speed of the detonation.
2. The trajectory of that "thingee" that flies over the plume apparently from the strongback.
I've looked closely at that "thingee" flying straight up from the strongback, stepping forwards and backwards in the video fame by frame several times. One thing I noticed is that if you assume that it originated at an elevation at or above where the explosion seems to be centered, and if you try to visually extrapolate the reverse-trajectory while stepping the video backwards, it seems like that part must have been launched a few frames after the initial explosion began (i.e. running backwards it seems it would reach it's expected starting point before the shrinking fireball disappears). That might indicate that it was launched from some part on the strongback due to pressure buildup from the original explosion coming from a point on the rocket to the left and possibly a bit below.
Of course my technique is very inaccurate and I could be wrong about the timing of the trajectory but that's what it looks like to me.
The LOX dome in the common bulkhead impinges the RP-1 tank, is that correct?
Bolded red here (side view): < Payload ] ( LOX ) RP1) |< M-vac
So it would take an RP-1 overpressurization (or LOX depress) to invert the dome. Right?
My own pet theory is that an RP-1 overpress inverted the bulkhead, overpressing the LOX tank and splitting the two at the now-weakened bulkhead. Hot twisted bulkhead metal ignited the mixing propellants.
Still, given the energy, it's difficult to imagine how the payload wasn't propelled upwards with the pressure from the LOX if the tank split circumferentially. Sort of like how STS-51L's ET was propelled forward when the aft LH2 dome split off.
Also, when they're doing LOX loading, is the RP-1 in the tanks pressurized? Because if there's no pressurized fuel source at this point in the prop loading process (in the tanks or the feedlines) that would make an external fuel/air explosion seem a lot less likely, wouldn't it?
Two things bother me greatly.
1. The onset speed of the detonation.
2. The trajectory of that "thingee" that flies over the plume apparently from the strongback.
I've looked closely at that "thingee" flying straight up from the strongback, stepping forwards and backwards in the video fame by frame several times. One thing I noticed is that if you assume that it originated at an elevation at or above where the explosion seems to be centered, and if you try to visually extrapolate the reverse-trajectory while stepping the video backwards, it seems like that part must have been launched a few frames after the initial explosion began (i.e. running backwards it seems it would reach it's expected starting point before the shrinking fireball disappears). That might indicate that it was launched from some part on the strongback due to pressure buildup from the original explosion coming from a point on the rocket to the left and possibly a bit below.
Of course my technique is very inaccurate and I could be wrong about the timing of the trajectory but that's what it looks like to me.
If you make the following assumption, do you come to the same conclusion?
1. The vertical component is < 50% of the total velocity
2. The horizontal component towards the camera and left is > 50% of the total velocity.
lot of discussion about what is where on the tower in relation to the explosion.
this wired article has a couple of closeups of the tower and stage in the area you guys are talking about. Older Falcon variant i think, but i doubt the geometry has changed much
http://www.wired.com/2012/05/the-launch-pad-spacex-falcon-9-ready-for-liftoff/
also here's a hi res closeup i found linked off reddit of interstage area, a little lower down, good view of the service lines on the tower
http://i.imgur.com/7LL2HUp.jpg
bottom line - unless i'm looking at the images wrong, there isn't much beyond ECS (AC) and power running up past the lower part of the 2nd stage.
Here is an image of a more up to date iteration of the vehicle: https://c2.staticflickr.com/2/1671/26217360302_b66c3e384e_o.jpg
Edit: And the fairing version:
https://c2.staticflickr.com/6/5766/23526044959_5bfe74bc88_o.jpg
Not sure where to ask this type of question, and I think it is obvious why one would ask it after such an event, but how tight is security in the launch industry? Meaning throughout the process, from origin of the rocket up to ignition?
Have there been any helicopter aerial views of the pad anywhere on the net post accident. I haven"t seen any yet. Question is how long is the pad out of commission per how much damage is there.It's an Air Force Base. I'm sure there are strict restrictions on photographers in civilian news copters.
Two things bother me greatly.
1. The onset speed of the detonation.
2. The trajectory of that "thingee" that flies over the plume apparently from the strongback.
I've looked closely at that "thingee" flying straight up from the strongback, stepping forwards and backwards in the video fame by frame several times. One thing I noticed is that if you assume that it originated at an elevation at or above where the explosion seems to be centered, and if you try to visually extrapolate the reverse-trajectory while stepping the video backwards, it seems like that part must have been launched a few frames after the initial explosion began (i.e. running backwards it seems it would reach it's expected starting point before the shrinking fireball disappears). That might indicate that it was launched from some part on the strongback due to pressure buildup from the original explosion coming from a point on the rocket to the left and possibly a bit below.
Of course my technique is very inaccurate and I could be wrong about the timing of the trajectory but that's what it looks like to me.
If you make the following assumption, do you come to the same conclusion?
1. The vertical component is < 50% of the total velocity
2. The horizontal component towards the camera and left is > 50% of the total velocity.
Yes, whether or not I'm right or wrong, I don't see how the horizontal component matters at all.
Even if the explosion was ignited outside the rocket a failure of the rocket could still be the source of the oxygen/rp-1.The LOX dome in the common bulkhead impinges the RP-1 tank, is that correct?
Bolded red here (side view): < Payload ] ( LOX ) RP1) |< M-vac
So it would take an RP-1 overpressurization (or LOX depress) to invert the dome. Right?
My own pet theory is that an RP-1 overpress inverted the bulkhead, overpressing the LOX tank and splitting the two at the now-weakened bulkhead. Hot twisted bulkhead metal ignited the mixing propellants.
Still, given the energy, it's difficult to imagine how the payload wasn't propelled upwards with the pressure from the LOX if the tank split circumferentially. Sort of like how STS-51L's ET was propelled forward when the aft LH2 dome split off.
This is a key indication that the initial explosion was external to the tank.
A detonation inside the tank would be vastly more energetic than the pressure from a COPV failure -- which itself would have sufficient energy to launch the payload upwards. It just sat there...
External explosion compromises the second stage tankage, fuel/lox waterfalls onto pad below, lower stage detonates, and finally, payload comes tumbling down.
Posting from my phone, so apologies for this not being the most readable.
That second pic there shows that there is a bit of a "cradle" on the strong back right about where the intertank is, if I'm looking at it right. This perks my interest and goes along with something else I've been wondering. Watching the video, my mind sees relative motion between the rocket and strong back (very small probably nothing). I've been thinking this was a trick of how far away the camera is etc. But what if it isn't? What if there was some relative motion there? Could this "cradle" have actually punctured the skin of the rocket? Does anyone know the wind speeds, it looked like a relatively stiff breeze from looking at the vent gasses (not really a good judge of things). I'm sure there are wind constraints even for a static test right?
I honestly think I'm crazy on this theory, but thought I'd throw it out to be debunked here.
Posting from my phone, so apologies for this not being the most readable.
That second pic there shows that there is a bit of a "cradle" on the strong back right about where the intertank is, if I'm looking at it right. This perks my interest and goes along with something else I've been wondering. Watching the video, my mind sees relative motion between the rocket and strong back (very small probably nothing). I've been thinking this was a trick of how far away the camera is etc. But what if it isn't? What if there was some relative motion there? Could this "cradle" have actually punctured the skin of the rocket? Does anyone know the wind speeds, it looked like a relatively stiff breeze from looking at the vent gasses (not really a good judge of things). I'm sure there are wind constraints even for a static test right?
I honestly think I'm crazy on this theory, but thought I'd throw it out to be debunked here.
The cradle is in pretty much the exact place the explosion started.
Probably correlation, not causation.
While I am not an official spokesperson for either Cape Canaveral Air Force Station Fire Department or Kennedy Space Center Fire Department, I am a member of CCAFS FD and was on scene at yesterday's anomaly and was involved with the eventual extinguishment of the remaining fires. I can confirm that NO personnel from either side were injured or airlifted from the scene. The Air Force's Explosive Ordinance Disposal team preceded closely in front of fire crews and did a superb job clearing a path for us to follow and approach the pad.
(On how bad the pad was damaged) Quite. Granted, I'm not in construction or an engineer but it seems like it will be months before the pad is usable. Dozens of pressurized vessels and tanks were destroyed including 5-6 pressurized rail cars. The gantry itself, while still standing appears to be a total loss, as may be a lightening arrest tower at the corner of the pad. Several buildings located on or near the pad are either destroyed or severely damaged. There's no power at the moment and I can tell you from first-hand experience that the water mains and hydrants are compromised. Debris made it as far as pad 39A, which is quite a distance. They'll be finding pieces of it in the surrounding woods and beach line for years, just as they've found pieces of 1997's Delta II mishap as recently as a year or two ago. I have loads of pictures and video, including the initial walk-down of the pad with Fire, EOD, SpaceX, and AF investigators, and know people who have posted them to social media but without SpaceX' and the Air Force's expressed permission, I'm wary of posting them.
I'm fairly certain I saw a rocket motor, or at least it's nozzle, directly under the gantry on top of the pad and a black composite tank that looked fairly intact off in the field, but that's about all that was recognizable.
The hangar actually doesn't appear damaged but I'm sitting on the opposite side of the pad right now and can't see it close up. As for concrete, I'm not sure yet but plumbing and piping leading into/out of the pad definitely is.
(on debris flying to 39A) It does seem unlikely that it would travel that distance but a contingent of EOD was dispatched to 39A for report of debris.
When I have a better handle on permissions, I'll post some. They're pretty interesting.
Yes, passive air cooling and I was not 100% certain if they did a air/GN2 change-over for the PLF purge.
I did a cursory search back to page 12, and no one had posted this... off of twitter, picked it up yesterday. The creator put the fire ball and the Dragon Abort vid together and sort of proved that Dragon would escape with plenty of margin... I hedged my comment, because I know that there may be purists who will knock his effort...
https://twitter.com/StateMachines/status/771535425328459780
User Squeazle (https://www.reddit.com/user/Squeazle) on reddit, claiming to be with the CCAFS FD, posted a few things re: pad status. Goes without saying that his information cannot be confirmed, but his post history does seem to back up his position.QuoteWhile I am not an official spokesperson for either Cape Canaveral Air Force Station Fire Department or Kennedy Space Center Fire Department, I am a member of CCAFS FD and was on scene at yesterday's anomaly and was involved with the eventual extinguishment of the remaining fires. I can confirm that NO personnel from either side were injured or airlifted from the scene. The Air Force's Explosive Ordinance Disposal team preceded closely in front of fire crews and did a superb job clearing a path for us to follow and approach the pad.
(On how bad the pad was damaged) Quite. Granted, I'm not in construction or an engineer but it seems like it will be months before the pad is usable. Dozens of pressurized vessels and tanks were destroyed including 5-6 pressurized rail cars. The gantry itself, while still standing appears to be a total loss, as may be a lightening arrest tower at the corner of the pad. Several buildings located on or near the pad are either destroyed or severely damaged. There's no power at the moment and I can tell you from first-hand experience that the water mains and hydrants are compromised. Debris made it as far as pad 39A, which is quite a distance. They'll be finding pieces of it in the surrounding woods and beach line for years, just as they've found pieces of 1997's Delta II mishap as recently as a year or two ago. I have loads of pictures and video, including the initial walk-down of the pad with Fire, EOD, SpaceX, and AF investigators, and know people who have posted them to social media but without SpaceX' and the Air Force's expressed permission, I'm wary of posting them.
I'm fairly certain I saw a rocket motor, or at least it's nozzle, directly under the gantry on top of the pad and a black composite tank that looked fairly intact off in the field, but that's about all that was recognizable.
The hangar actually doesn't appear damaged but I'm sitting on the opposite side of the pad right now and can't see it close up. As for concrete, I'm not sure yet but plumbing and piping leading into/out of the pad definitely is.
(on debris flying to 39A) It does seem unlikely that it would travel that distance but a contingent of EOD was dispatched to 39A for report of debris.
When I have a better handle on permissions, I'll post some. They're pretty interesting.
How about this.
Let's say there was a small, maybe pin-hole leak in the RP-1 fueling umbilical, and during fueling it sprayed the top of the strongback with RP1. Kerosene evaporates slowly so it can hang around for a while.
It looks like there's a GOX stream near the strongback. See the arrow below. That spot seems to correspond to the initiation location as determined by the diffraction spikes.
What if that GOX stream and the hypothetical slowly-evaporating RP-1 from the hypothetical leak finally got to sufficient concentrations, just due to just the right (or wrong) wind conditions that it could ignite into a fuel-air explosion given an ignition source? That small-ish explosion ruptures the tanks, and everything falls, burning on the way down.
Yes, that's where the explosion appears to start, thus my question.
Clearly correlation is not causation, but merely stating a trite old saying doesn't rule it out either.
What are the wind constraints for a static fire? Is there something that guaruntees there can be no relative motion between the rocket and strongback in that location? The skin wouldn't even necessarily need to be punctured either, a big enough dent could cause the tanks to buckle under pressure too.
Yes, passive air cooling and I was not 100% certain if they did a air/GN2 change-over for the PLF purge.
The air is also cooled along with being filtered. But at that point in the countdown, it should be GN2
User Squeazle (https://www.reddit.com/user/Squeazle) on reddit, claiming to be with the CCAFS FD, posted a few things re: pad status. Goes without saying that his information cannot be confirmed, but his post history does seem to back up his position.QuoteWhile I am not an official spokesperson for either Cape Canaveral Air Force Station Fire Department or Kennedy Space Center Fire Department, I am a member of CCAFS FD and was on scene at yesterday's anomaly and was involved with the eventual extinguishment of the remaining fires. I can confirm that NO personnel from either side were injured or airlifted from the scene. The Air Force's Explosive Ordinance Disposal team preceded closely in front of fire crews and did a superb job clearing a path for us to follow and approach the pad.
(On how bad the pad was damaged) Quite. Granted, I'm not in construction or an engineer but it seems like it will be months before the pad is usable. Dozens of pressurized vessels and tanks were destroyed including 5-6 pressurized rail cars. The gantry itself, while still standing appears to be a total loss, as may be a lightening arrest tower at the corner of the pad. Several buildings located on or near the pad are either destroyed or severely damaged. There's no power at the moment and I can tell you from first-hand experience that the water mains and hydrants are compromised. Debris made it as far as pad 39A, which is quite a distance. They'll be finding pieces of it in the surrounding woods and beach line for years, just as they've found pieces of 1997's Delta II mishap as recently as a year or two ago. I have loads of pictures and video, including the initial walk-down of the pad with Fire, EOD, SpaceX, and AF investigators, and know people who have posted them to social media but without SpaceX' and the Air Force's expressed permission, I'm wary of posting them.
I'm fairly certain I saw a rocket motor, or at least it's nozzle, directly under the gantry on top of the pad and a black composite tank that looked fairly intact off in the field, but that's about all that was recognizable.
The hangar actually doesn't appear damaged but I'm sitting on the opposite side of the pad right now and can't see it close up. As for concrete, I'm not sure yet but plumbing and piping leading into/out of the pad definitely is.
(on debris flying to 39A) It does seem unlikely that it would travel that distance but a contingent of EOD was dispatched to 39A for report of debris.
When I have a better handle on permissions, I'll post some. They're pretty interesting.
I'm thinking history will show JCSAT-16 as the last rocket launched from SLC-40.... it's done... :'( :(
This is a very small reference point but the oxygen show at the local science museum burns a cotton ball, uses a new one dipped in liquid oxygen and causes an explosion that rattles the ceiling tiles and you feel the concussion rattling you.
Point is, that much concentrated oxygen can support rapid burning (explosion) with many materials that we wouldn't think of as explosive.
Once that initial point started, it took everything else with it. A distinctive pattern of arcing on the remains of the TEL may tell much.
This is a very small reference point but the oxygen show at the local science museum burns a cotton ball, uses a new one dipped in liquid oxygen and causes an explosion that rattles the ceiling tiles and you feel the concussion rattling you.Ask any good welder about precautions around oxygen gas and hydrocarbons...
Point is, that much concentrated oxygen can support rapid burning (explosion) with many materials that we wouldn't think of as explosive.
Once that initial point started, it took everything else with it. A distinctive pattern of arcing on the remains of the TEL may tell much.
Somewhere in the volumes of written word from the last 24 hours, there was the phrase from SpaceX, "Catastrophic abort."
Nope, this was never said by SpaceX.
Other persistent misunderstandings: there were early conflicting reports that the incident happened at T-3 and T-5. Evidence from the timeline and strongback/cradle position indicates that it happened some time before T-4:10, which is when the cradle is opened.
So still I think something failed in the rocket, caused a fuel air or fuel gox mix to form, and then something else (what?) Ignited it.
Somewhere in the volumes of written word from the last 24 hours, there was the phrase from SpaceX, "Catastrophic abort."
Nope, this was never said by SpaceX.
Other persistent misunderstandings: there were early conflicting reports that the incident happened at T-3 and T-5. Evidence from the timeline and strongback/cradle position indicates that it happened some time before T-4:10, which is when the cradle is opened.
Do we know that SpaceX wasn't deep into processing an abort at the time of explosion, and that the strongback hadn't been retracted at some point?
If you have a sudden fracture of the RP-1 under pressure a jet of fuel vapour could shoot out into the gaseous Ox vapour cloud, could with the energy of molecule collisions, cause a spontaneous ignition.So still I think something failed in the rocket, caused a fuel air or fuel gox mix to form, and then something else (what?) Ignited it.
The ignition source appears to be in the vicinity of the cradle -- metal scraping during retraction ops? With enough O2, it really doesn't take much, and there's plenty of gox venting. I don't think the cause of the ignition is that interesting. The fact that there was something to ignite is the troubling bit.
Somewhere in the volumes of written word from the last 24 hours, there was the phrase from SpaceX, "Catastrophic abort."
Nope, this was never said by SpaceX.
Other persistent misunderstandings: there were early conflicting reports that the incident happened at T-3 and T-5. Evidence from the timeline and strongback/cradle position indicates that it happened some time before T-4:10, which is when the cradle is opened.
Do we know that SpaceX wasn't deep into processing an abort at the time of explosion, and that the strongback hadn't been retracted at some point?
Nope
Are the COPVs in the LOX tank something that is only done in the Falcon 9's second stage? Where is the GHe on the booster?Same design for both stages.
Could lc-39a be used as a launch site if lc-40 is not yet ready for when the falcon 9 is ready for return to flight?
We have footage of the strongback upright and closed on the vehicle continuously for more than a minute before the fireball.
We have the SpaceX statement that the anomaly occurred "during propellant loading of the vehicle"; if they were several minutes into an abort they would likely have been draining prop, not loading it.
First, let me say as a layperson how much I appreciate this forum for discussions like this...thank you!
Great discussions!
My question - does anyone know if/when more video will be released? Does anyone know if there were any other cameras nearby?
This is separate from asking when SpaceX will share any info or video...thanks!
Somewhere in the volumes of written word from the last 24 hours, there was the phrase from SpaceX, "Catastrophic abort."
Nope, this was never said by SpaceX.
Other persistent misunderstandings: there were early conflicting reports that the incident happened at T-3 and T-5. Evidence from the timeline and strongback/cradle position indicates that it happened some time before T-4:10, which is when the cradle is opened.
Do we know that SpaceX wasn't deep into processing an abort at the time of explosion, and that the strongback hadn't been retracted at some point?Nope
We have footage of the strongback upright and closed on the vehicle continuously for more than a minute before the fireball.
We have the SpaceX statement that the anomaly occurred "during propellant loading of the vehicle"; if they were several minutes into an abort they would likely have been draining prop, not loading it.
Yes, that's where the explosion appears to start, thus my question.
Clearly correlation is not causation, but merely stating a trite old saying doesn't rule it out either.
What are the wind constraints for a static fire? Is there something that guaruntees there can be no relative motion between the rocket and strongback in that location? The skin wouldn't even necessarily need to be punctured either, a big enough dent could cause the tanks to buckle under pressure too.
I've overlaid an image from immediately before the explosion over one a couple of minutes after it.
It shows the strongback buckled at pretty much the point you're referring to, which could be interpreted as it being damaged by the initial explosion and subsequently failing there.
However, it looks like the buckling of the strongback was caused by it taking the weight of the payload and was twisted as it fell - but it still failed at the same point.
I've marked that point on a clean image of the top of the vehicle (with a Dragon) and the construction of the strongback is different at that point.
It looks like it has what I would consider to be bottle screws, which would enable the height of the top of the strongback to be altered by extending the. (No doubt someone can cast some light on what they are?)
This is probably the weakest point in the top of the structure, so it's not surprising that it deformed there.
In short: although strongback seems to have part-failed at the point of the initial explosion, it's probably nothing more than correlation.
I don't know where this "abort" theory comes from, but it's not NSF or SpaceX. I've read every word published by spacex and every word of the NSF threads and I didn't see anything similar until AncientU's post. I suspect you guys are getting unsourced speculation from less-credible sites and then getting it mixed up in your minds as something real.
"There is NO threat to general public from catastrophic abort during static test fire at SpaceX launch pad at CCAFS this morning," the Brevard County Emergency Operations Center said.
I don't know where this "abort" theory comes from, but it's not NSF or SpaceX. I've read every word published by spacex and every word of the NSF threads and I didn't see anything similar until AncientU's post. I suspect you guys are getting unsourced speculation from less-credible sites and then getting it mixed up in your minds as something real.
I think it comes from the Brevard County Emergency Operations Center. I didn't take it too literally, though it's possible that they detected something was going south a few seconds before the fireball and attempted to abort.Quote"There is NO threat to general public from catastrophic abort during static test fire at SpaceX launch pad at CCAFS this morning," the Brevard County Emergency Operations Center said.
source: http://www.upi.com/Top_News/US/2016/09/01/SpaceX-Falcon-9-explodes-in-catastrophic-abort-on-Florida-launch-pad/4371472736796/
I don't know where this "abort" theory comes from, but it's not NSF or SpaceX. I've read every word published by spacex and every word of the NSF threads and I didn't see anything similar until AncientU's post. I suspect you guys are getting unsourced speculation from less-credible sites and then getting it mixed up in your minds as something real.
I think it comes from the Brevard County Emergency Operations Center. I didn't take it too literally, though it's possible that they detected something was going south a few seconds before the fireball and attempted to abort.Quote"There is NO threat to general public from catastrophic abort during static test fire at SpaceX launch pad at CCAFS this morning," the Brevard County Emergency Operations Center said.
source: http://www.upi.com/Top_News/US/2016/09/01/SpaceX-Falcon-9-explodes-in-catastrophic-abort-on-Florida-launch-pad/4371472736796/
The fact that most LOVs are early in the program seems pretty obvious. The Shuttle was an exception.Every time we have one on these events my thoughts are always the same. Better now than when we have a crew on board. Pick up the pieces, find the cause(s), fix them and get flying again. Best of luck to the teams at SpaceX.
Yes, and this is exactly why I think it's so much more dangerous to put a crew on SLS than a crew on either commercial crew vehicle. Atlas V and Falcon 9 have lots of non-crew launches to find problems before crews are put on them. SLS does not.
Complete nonsense. Please show me where launching fewer times has resulted in greater chance of loss of vehicle?
I see lots of mentions of "No pressure in the RP-1 umbilicals, RP-1 was already fully loaded". How do we know this is the case? SpaceX only said it was "during propellant loading", no mention of whether said "propellant" was the fuel or the oxidizer.
If this does turn out to be the second stage again then I think that SpaceX has to ask some very difficult management questions.
I doubt that working on the second stage is 'sexy'. The 'sexy' things to work on will be the reusable first stage, Falcon Heavy core, Raptor and BFS/BFR.
When you're dealing with a high oxygen content you don't even need a spark. Scuba tanks need oxygen safe cleaning for even mild oxygen enrichment as oil/grease can combust spontaneously, as can other materials.
I'm certain these risks are fully understood by all concerned, and that all materials including seals and lubricants are oxygen safe, but this is a "don't trust anything" investigation, and an ignition source not being present doesn't rule anything out.
Can't RP1 dispersed in air explode like that, if in the form of a fine mist?
Also, do they finish loading RP-1 on both stages before putting LOX on either?
How about this.
Let's say there was a small, maybe pin-hole leak in the RP-1 fueling umbilical, and during fueling it sprayed the top of the strongback with RP1. Kerosene evaporates slowly so it can hang around for a while.
It looks like there's a GOX stream near the strongback. See the arrow below. That spot seems to correspond to the initiation location as determined by the diffraction spikes.
What if that GOX stream and the hypothetical slowly-evaporating RP-1 from the hypothetical leak finally got to sufficient concentrations, just due to just the right (or wrong) wind conditions that it could ignite into a fuel-air explosion given an ignition source? That small-ish explosion ruptures the tanks, and everything falls, burning on the way down.
I don't know where this "abort" theory comes from, but it's not NSF or SpaceX. I've read every word published by spacex and every word of the NSF threads and I didn't see anything similar until AncientU's post. I suspect you guys are getting unsourced speculation from less-credible sites and then getting it mixed up in your minds as something real.
I think it comes from the Brevard County Emergency Operations Center. I didn't take it too literally, though it's possible that they detected something was going south a few seconds before the fireball and attempted to abort.Quote"There is NO threat to general public from catastrophic abort during static test fire at SpaceX launch pad at CCAFS this morning," the Brevard County Emergency Operations Center said.
source: http://www.upi.com/Top_News/US/2016/09/01/SpaceX-Falcon-9-explodes-in-catastrophic-abort-on-Florida-launch-pad/4371472736796/
Reading thru this thread... there seems to be some agreement that the T/E has a cradle/bumper like part that lines up with the dividing bulkhead on the inside of the S2 tank...
That makes sense as a place to place a fixed load point...
What I mean is, can we be sure that there was already LOX on board, and therefore, no pressure in the RP-1 umbilical?
Reading thru this thread... there seems to be some agreement that the T/E has a cradle/bumper like part that lines up with the dividing bulkhead on the inside of the S2 tank...
That makes sense as a place to place a fixed load point...
There is rubber bumpers there and on the clamps. No metal to metal contact
Question...
Suppose there is an major electrical fault that results in an arc being struck at that point...
Why... is not the question... the question is the outcome...
Put another way...
What happens if you (in effect) TIG weld (w/no shielding gas) on the outside of a thin wall aluminum tank full of ice cold LOX under pressure...
My guess is the AL will burn thru in a flash and then it all goes south from there...
Can't RP1 dispersed in air explode like that, if in the form of a fine mist?
Also, do they finish loading RP-1 on both stages before putting LOX on either?
Flour or even saw dust can combust like that, given enough dispersal and oxygen.
It's what is called a Fuel / Air Explosion.
Suppose there is an major electrical fault that results in an arc being struck at that point...
Why... is not the question... the question is the outcome...
How about this.
Let's say there was a small, maybe pin-hole leak in the RP-1 fueling umbilical, and during fueling it sprayed the top of the strongback with RP1. Kerosene evaporates slowly so it can hang around for a while.
It looks like there's a GOX stream near the strongback. See the arrow below. That spot seems to correspond to the initiation location as determined by the diffraction spikes.
What if that GOX stream and the hypothetical slowly-evaporating RP-1 from the hypothetical leak finally got to sufficient concentrations, just due to just the right (or wrong) wind conditions that it could ignite into a fuel-air explosion given an ignition source? That small-ish explosion ruptures the tanks, and everything falls, burning on the way down.
How could that pinhole leak, even if all the RP1 froze on the rocket's skin (which would bring it's flash point down, but anyway), be able to blow a hole in the wall from spontaneous ignition in open-air conditions, in 30 ms?
Yes... but what if they are aged and damp with dew from the rapidly chilling S2...
Along with a MAJOR electrical fault in the GSE/Rocket resulting in a voltage potential at that point of near contact....
This thread is long but not unreadable. I would ask posters to at least try to skim through most of it, since we're getting several repetitions of the same theories/images interleaved with actual new discussion or data, and people treating them as new, going over the same points over and over.
Reading thru this thread... there seems to be some agreement that the T/E has a cradle/bumper like part that lines up with the dividing bulkhead on the inside of the S2 tank...
That makes sense as a place to place a fixed load point...
Question...
Suppose there is an major electrical fault that results in an arc being struck at that point...
Why... is not the question... the question is the outcome...
Put another way...
What happens if you (in effect) TIG weld (w/no shielding gas) on the outside of a thin wall aluminum tank full of ice cold LOX under pressure...
My guess is the AL will burn thru in a flash and then it all goes south from there...
Yes... but what if they are aged and damp with dew from the rapidly chilling S2...
Along with a MAJOR electrical fault in the GSE/Rocket resulting in a voltage potential at that point of near contact....
Aged from what? They are fairly new. And what voltage potential?
Everyone seems to be ignoring the Very audible *Ploink* 3-4 sec prior to the detonation. This is the LOX tank failing, (mechanism irrelevant at this point), a large Qty of LOX will then be filling the stage and boiling off.
When you're dealing with a high oxygen content you don't even need a spark. Scuba tanks need oxygen safe cleaning for even mild oxygen enrichment as oil/grease can combust spontaneously, as can other materials.
I'm certain these risks are fully understood by all concerned, and that all materials including seals and lubricants are oxygen safe, but this is a "don't trust anything" investigation, and an ignition source not being present doesn't rule anything out.
I was wondering if some grease or cleaning solvent residue on the umbilical connectors could have caused the explosion. That was my first theory. Could have also been a natural contaminant that was wind borne into the proximity of the venting O2? Unlike pad 39 A, pad 40 is both closer to sea level and has more potential sources of natural contaminants in closer proximity. With a pure O2 environment, many different substances can and will spontaneously combust.
Is a COPV bursting and damaging the common bulkhead still a possible scenario?
Everyone seems to be ignoring the Very audible *Ploink* 3-4 sec prior to the detonation. This is the LOX tank failing, (mechanism irrelevant at this point), a large Qty of LOX will then be filling the stage and boiling off.
Do you not realize the distance that camera was at the time? Are you seriously implying that a "straining" bulkhead could be heard from 4 kilometers away???
The idea is that there's a cloud of kerosene vapor in the air outside the rocket body from evaporating RP1 on the strongback, that cloud gets ignited in the presence of extra gaseous oxygen, and the shock wave from that detonation ruptures the nearby tank.
From the video, it looks to me like the time between the flash and the time I see an enlarging fireball from the prop is about four frames, or 67ms. Since such a shock wave can move at several times the speed of sound and the speed of sound would allow it to move 23 meters in that time, it seems like there is sufficient time for that shock wave to rupture the tank and disperse the prop inside.
Obviously, there is insufficient evidence to support this sequence of events, so it's just a conjecture.
This thread is long but not unreadable. I would ask posters to at least try to skim through most of it, since we're getting several repetitions of the same theories/images interleaved with actual new discussion or data, and people treating them as new, going over the same points over and over.
Your message was reply #920 in this thread. Asking people to read, or even skim, 920 posts is asking a lot.
Occam's razor says that the noises are more likely to originate within the junkyard in which the videographer was located. This was discussed upthread.
Please don't post your personal theories multiple times. We've saw them the first time. If you didn't get a response it's because we didn't think it credible.
One theory post per person, please.
This thread is long but not unreadable. I would ask posters to at least try to skim through most of it, since we're getting several repetitions of the same theories/images interleaved with actual new discussion or data, and people treating them as new, going over the same points over and over.
Your message was reply #920 in this thread. Asking people to read, or even skim, 920 posts is asking a lot.
Yes... but what if they are aged and damp with dew from the rapidly chilling S2...
Along with a MAJOR electrical fault in the GSE/Rocket resulting in a voltage potential at that point of near contact....
Aged from what? They are fairly new. And what voltage potential?
460 volt from faulty GSE on the ground somewhere...
Two things bother me greatly.
1. The onset speed of the detonation.
2. The trajectory of that "thingee" that flies over the plume apparently from the strongback.
I've looked closely at that "thingee" flying straight up from the strongback, stepping forwards and backwards in the video fame by frame several times. One thing I noticed is that if you assume that it originated at an elevation at or above where the explosion seems to be centered, and if you try to visually extrapolate the reverse-trajectory while stepping the video backwards, it seems like that part must have been launched a few frames after the initial explosion began (i.e. running backwards it seems it would reach it's expected starting point before the shrinking fireball disappears). That might indicate that it was launched from some part on the strongback due to pressure buildup from the original explosion coming from a point on the rocket to the left and possibly a bit below.
Of course my technique is very inaccurate and I could be wrong about the timing of the trajectory but that's what it looks like to me.
If you make the following assumption, do you come to the same conclusion?
1. The vertical component is < 50% of the total velocity
2. The horizontal component towards the camera and left is > 50% of the total velocity.
Yes, whether or not I'm right or wrong, I don't see how the horizontal component matters at all.
In the pump house (or whatever it's called)...
Yes... but what if they are aged and damp with dew from the rapidly chilling S2...
Along with a MAJOR electrical fault in the GSE/Rocket resulting in a voltage potential at that point of near contact....
Aged from what? They are fairly new. And what voltage potential?
460 volt from faulty GSE on the ground somewhere...
What GSE?. It wouldn't be on the erector
Everyone seems to be ignoring the Very audible *Ploink* 3-4 sec prior to the detonation. This is the LOX tank failing, (mechanism irrelevant at this point), a large Qty of LOX will then be filling the stage and boiling off.
In the pump house (or whatever it's called)... 3 phase 480v pumps used to pump fluids from tanks to the pad...
It's exiting at a higher speed than the fireball which suggests it had a very energetic kick in the pants more so than the tank rupture explosion could provide. The more conventional explosion doesn't catch up with it until 2 seconds after it started its journey.
Looking hard at the pictures posted by hartspace and John Allen, it appears that the cradle just under the payload fairing is actuated by a hydralic cylinder with 2 black curved lines (hoses?) going back into the interior of the strongback. The anomaly happened close to the time the cradle should have been retracted. Is it possible that a ruptured hydralic line sent a mist of fluid into the oxygen rich environment below?
In the pump house (or whatever it's called)... 3 phase 480v pumps used to pump fluids from tanks to the pad...
That is not on the erector. It would be isolated.
In the pump house (or whatever it's called)...
My guess is 3 phase 480v pumps with Freq drives used to pump RP-1/LOX from tanks to the pad...
If they use something besides explosion proof off the shelf stuff... then correctly me please...
My points was not to argue the source of the voltage issue causing the arc...
My point was... IF an arc struck at that point of near contact... what would happen...
Since unshielded (by gas) AL usually vaporizes and burns in such a situation...
Aided by the escaping LOX liguid... poof then unzip...
In some way not able to withstand the electrical potential that exists (in error) across the joint... YES!!
In the pump house (or whatever it's called)... 3 phase 480v pumps used to pump fluids from tanks to the pad...
That is not on the erector. It would be isolated.
It should be electrically isolated... yes... but what if there is a fault in the equipment Jim...
Reposting my later edit to above post...In the pump house (or whatever it's called)...
My guess is 3 phase 480v pumps with Freq drives used to pump RP-1/LOX from tanks to the pad...
If they use something besides explosion proof off the shelf stuff... then correctly me please...
My points was not to argue the source of the voltage issue causing the arc...
My point was... IF an arc struck at that point of near contact... what would happen...
Since unshielded (by gas) AL usually vaporizes and burns in such a situation...
Added by the escaping LOX liguid... poof then unzip...
and the rubber pads are worn?
But anyways, there isn't going to be that kind of voltage on the erector. The pumps are hundreds of feet away from the launch.But what if (for some reason) there was.... ;)
It's exiting at a higher speed than the fireball which suggests it had a very energetic kick in the pants more so than the tank rupture explosion could provide. The more conventional explosion doesn't catch up with it until 2 seconds after it started its journey.
You do realize an expanding cloud of gas has a much different drag coefficient than a twisted piece of metal?
In some way not able to withstand the electrical potential that exists (in error) across the joint... YES!!
In some way not able to withstand the electrical potential that exists (in error) across the joint... YES!!
Meh, no. Too many failures required. RP-1 availability, bad rubber, short
The so-called "thingee" is probably one of the high pressure helium bottles liberated by the 2nd stage rupture. There seem to be a bunch of "it bounced off of this thing" or "banked off of that thing" or "was a secondary explosion" type comments, but I think it's simpler than that; it's probably a high pressure helium tank that is still venting helium and therefore does NOT follow a parabolic trajectory. I'm struck by the similarity between the the "thingee" flying clear of the fireball yesterday for this SpaceX failure and the helium tank skipping along the water immediately after the Sea Launch NSS8 Failure in 2007.
I assume that there are multiple COPV helium bottles in the second stage, so that even if one failed, there would still be others left flying about. But I don't know about the internals of the F9, so I defer to others.
For the Sea Launch failure, the high pressure helium bottle is barely visible in the youtube versions of the video, but shows up much better in some of the L2 content
In some way not able to withstand the electrical potential that exists (in error) across the joint... YES!!
Meh, no. Too many failures required. RP-1 availability, bad rubber, short
Got a point Jim.
Do you think that a metallic fracture of an umbilical connector could provide enough heat to cause a combustion event in the high O2 environment that would result?
Yah, I took a physics class or two in my time. I think what I'm trying to suggest is this. If you mix the RP1 and LOX you obviously get a bang, but the mixing still takes a finite time. The two tanks don't merge equally and then go boom, there has to be a burn front following the mixing front which to me is why it takes relatively long (seconds) for the 2nd stage to combust. A perfect mix probably has a burn rate of 5,000 feet per second, more or less. Frame 1 indicates a burn rate of between 2,000 and 5,000 feet per second, which is certainly enough to kick the thingee beyond the combustion front of the tank rupture. Several points.
A well mixed cloud will burn at thousands of feet per second.
A poorly mixed cloud will meander as you suggest.
However, a tank rupture is too slow and in the wrong place to get the thingee moving.
To me, something other than tank rupture propels the thingee on its path and initiates the tank rupture. The tank rupture event is too slow to propel the thingee.
The so-called "thingee" is probably one of the high pressure helium bottles liberated by the 2nd stage rupture. There seem to be a bunch of "it bounced off of this thing" or "banked off of that thing" or "was a secondary explosion" type comments, but I think it's simpler than that; it's probably a high pressure helium tank that is still venting helium and therefore does NOT follow a parabolic trajectory. I'm struck by the similarity between the the "thingee" flying clear of the fireball yesterday for this SpaceX failure and the helium tank skipping along the water immediately after the Sea Launch NSS8 Failure in 2007.
I assume that there are multiple COPV helium bottles in the second stage, so that even if one failed, there would still be others left flying about. But I don't know about the internals of the F9, so I defer to others.
For the Sea Launch failure, the high pressure helium bottle is barely visible in the youtube versions of the video, but shows up much better in some of the L2 content
I like the idea, but there are a few things that make me disagree.
1. eeergo attempted to do a trajectory analysis, picture 1 below. You can actually trace it back to frame 4 of the explosion. It's not coming from the F9, and if it's a bounce obscured by the 1st three frames, it's an amazing bounce.
2. It doesn't resemble a helium bottle, picture 2 below.
In some way not able to withstand the electrical potential that exists (in error) across the joint... YES!!
Meh, no. Too many failures required. RP-1 availability, bad rubber, short
Got a point Jim.
Do you think that a metallic fracture of an umbilical connector could provide enough heat to cause a combustion event in the high O2 environment that would result?
Wouldn't the rubber itself burn rather nicely, perhaps explosively, in a pure oxygen environment?
Occam's razor says that the noises are more likely to originate within the junkyard in which the videographer was located. This was discussed upthread.
Please don't post your personal theories multiple times. We saw them the first time. If you didn't get a response it's because we didn't think it credible, or interesting, it sufficiently different from the last person who posted that theory.
One theory post per person, please.
My problem with your hinge idea is that it has to hinge somewhere on the cylinder of the rocket. That's ok, but if you use your own trajectory plot, it has to hinge THROUGH the strongback at the beginning of the journey. It's a nice concept, but the starting point of that fragment doesn't strike me as a hinge action from the skin of the stage.
The so-called "thingee" is probably one of the high pressure helium bottles liberated by the 2nd stage rupture. There seem to be a bunch of "it bounced off of this thing" or "banked off of that thing" or "was a secondary explosion" type comments, but I think it's simpler than that; it's probably a high pressure helium tank that is still venting helium and therefore does NOT follow a parabolic trajectory. I'm struck by the similarity between the the "thingee" flying clear of the fireball yesterday for this SpaceX failure and the helium tank skipping along the water immediately after the Sea Launch NSS8 Failure in 2007.
I assume that there are multiple COPV helium bottles in the second stage, so that even if one failed, there would still be others left flying about. But I don't know about the internals of the F9, so I defer to others.
For the Sea Launch failure, the high pressure helium bottle is barely visible in the youtube versions of the video, but shows up much better in some of the L2 content
I like the idea, but there are a few things that make me disagree.
1. eeergo attempted to do a trajectory analysis, picture 1 below. You can actually trace it back to frame 4 of the explosion. It's not coming from the F9, and if it's a bounce obscured by the 1st three frames, it's an amazing bounce.
2. It doesn't resemble a helium bottle, picture 2 below.
This lines up with the idea that the explosion was more likely external.
As the payload appears to have still been attached to the gantry for several seconds after the explosion, it seems that it was more likely that the tanks were ruptured by an external explosion, as an internal explosion would have lifted the payload off the gantry and further away from the launch vehicle. An internal explosion would have acted as more like a cannon in this respect, than as a rupturing tank.
I'll bet we see a big new claw at the top of the strongback. Big enough to hold the payload. =/
> AC
The line with the S curve is insulated for cryogenic supply, either LOX or chilled RP-1. In other images, one of the large stage 1 umbilicals comes directly off of it. Looks like it's part of the LOX supply, with the bigger diameter pipe to the left being for oxygen gas return. The bigger pipe splits and also goes to a vent at the top of the strongback.
Large cryogenic supplies are typically a loop, because the pipe has to be chilled before liquid can flow through safely / reasonably. Its chilled by first pumping cold gas, recirculating the gas through a return pipe to a refrigerator that drives the temperature lower over time.
> ACI find this post from a new user (today, 2 posts) fairly interesting as it directly contradicts info from Jim and couple of others who claimed no pressure in fuel lines and AC for the piping.
The line with the S curve is insulated for cryogenic supply, either LOX or chilled RP-1. In other images, one of the large stage 1 umbilicals comes directly off of it. Looks like it's part of the LOX supply, with the bigger diameter pipe to the left being for oxygen gas return. The bigger pipe splits and also goes to a vent at the top of the strongback.
Large cryogenic supplies are typically a loop, because the pipe has to be chilled before liquid can flow through safely / reasonably. Its chilled by first pumping cold gas, recirculating the gas through a return pipe to a refrigerator that drives the temperature lower over time.
There is pressurized fuel and oxidizer in the supply lines all the way through liftoff.
Goes without saying that we're all hoping for a safe return to flight as soon as possible.
I'll bet we see a big new claw at the top of the strongback. Big enough to hold the payload. =/
Late to the thread but this failure makes me wonder why not just test fire the rocket without the payload at an adjacent stand so that if it goes boom you don't lose the pad and payload?Because static fire checks the pad as much as it checks the vehicle?
Out of curiosity: what "primary event" are you suggesting imparted such a phenomenal force to the (large) piece, that you claim overshadows the powerful burst+explosion acceleration?
Other rockets don't require them.Late to the thread but this failure makes me wonder why not just test fire the rocket without the payload at an adjacent stand so that if it goes boom you don't lose the pad and payload?Because static fire checks the pad as much as it checks the vehicle?
Late to the thread but this failure makes me wonder why not just test fire the rocket without the payload at an adjacent stand so that if it goes boom you don't lose the pad and payload?
My problem with your hinge idea is that it has to hinge somewhere on the cylinder of the rocket. That's ok, but if you use your own trajectory plot, it has to hinge THROUGH the strongback at the beginning of the journey. It's a nice concept, but the starting point of that fragment doesn't strike me as a hinge action from the skin of the stage.
Coming back to this, since you re-used the trajectory composite for the helium bottle comparison: I don't see why it'd hinge through the T/E? I actually favor the idea of piece coming from the S2 wall at ~45º from the line-of-sight from the camera to the stage - that, or being a T/E piece blown upward and toward the camera by the blast.
Out of curiosity: what "primary event" are you suggesting imparted such a phenomenal force to the (large) piece, that you claim overshadows the powerful burst+explosion acceleration?
The primary event occurs during Frame 1 of the explosion video sequence. From Frame 0 where everything is fine, Frame 1 shows a measurable pixel saturation region of roughly 35 feet horizontal and 85 feet vertical. That's an explosion with a wave front between 2,000 and 5,000 feet per second, depending on when it started during the integration time of the CCD or whatever the camera used. A fuel air explosive would go about 5,000 feet per second. TNT would go about 19,000 feet per second. That first frame shows an explosion propagating at 2 to 5 times the speed of sound. That to me is the "primary" event.
After frame 1, the fireball growth is significantly slower, which by Frame 4 includes the tank rupture explosion, which piddles along at maybe 100-200 feet per second. That's to me, the secondary event.
> AC
1. The line with the S curve is insulated for cryogenic supply, either LOX or chilled RP-1. In other images, one of the large stage 1 umbilicals comes directly off of it. Looks like it's part of the LOX supply, with the bigger diameter pipe to the left being for oxygen gas return. The bigger pipe splits and also goes to a vent at the top of the strongback.
2. Large cryogenic supplies are typically a loop, because the pipe has to be chilled before liquid can flow through safely / reasonably. Its chilled by first pumping cold gas, recirculating the gas through a return pipe to a refrigerator that drives the temperature lower over time.
3. There is pressurized fuel and oxidizer in the supply lines all the way through liftoff.
4. I'll bet we see a big new claw at the top of the strongback. Big enough to hold the payload. =/
That's a good point. I know one of the Russian N1 rockets fell onto the pad but that was also a long time ago. And Antares failed shortly after take off.Late to the thread but this failure makes me wonder why not just test fire the rocket without the payload at an adjacent stand so that if it goes boom you don't lose the pad and payload?
Sure, but counterargument would be that, while yes, spaceflight is hard, it's been about 57 years since a rocket was lost on the ground in the US. Is it worth the time and money to change procedures to prevent something that is very very rarely a problem?
"Jonathan McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics who keeps a respected catalog of space activities, said he believes the last time such a mishap occurred at Cape Canaveral on an orbital-class rocket before liftoff was in 1959, when an Atlas-Able booster exploded during a static fire test."
https://spaceflightnow.com/2016/09/01/spacex-rocket-and-israeli-satellite-destroyed-in-launch-pad-explosion/space
I think the only way to resolve our difference is via SKYPE or something. :) I see that piece going vertical in Frame 4. For it to hinge, it has to shoot to the right at some grotesque speed and then hinge up and left at some lower speed. Kinda like the Dallas magic bullet. Possible, but hard to explain off hand.
If the explosion starts in the tower and it's a piece of the tower getting blow up and left, it doesn't require hinging.
Also, if you look at the geometry, it's non-symmetric, appears to have a hole or divot, and might be a closed cylinder. So the magic bullet not only changes the trajectory it blasts it from an aluminum tank wall into a doughnut.
Please read this as an attempt at gallows humor. I don't know what really happened, but much as you're skeptical of some of my ideas, I'm a bit skeptical of this one from you. :)
John,
With respect, unless I am very mistaken, the release of pressurized gas would result in adiabatic cooling, not heating. Boyle's law, etc. As the pressure of a mass of air is decreased, it cools.
Please let me know if I'm missing something.
Other rockets don't require them.Late to the thread but this failure makes me wonder why not just test fire the rocket without the payload at an adjacent stand so that if it goes boom you don't lose the pad and payload?Because static fire checks the pad as much as it checks the vehicle?
Chronology of the video:
Frame 1: fuel-air explosive type of energetic event
Frame 3: Cloud of unburned material becomes visible behind the initial fireball
Frame 10: Unknown object emerges from the top of the fireball (while being not the first debris flying around, this one is largest)
Frame 32-33: First stage RP-1 tank rupture.
Frame 118: Stage 1 LOX tank BLEVE?
"Require" is sort of a un-useful statement. Forget "require". SpaceX doesn't do static fires because they are "required."
They do static fires because, considering the relevant tradeoffs, economic and technical, they believe it is better to do static fires at the launch site rather than not do them.
Life is the real world is always full of tradeoffs. SpaceX makes those tradeoffs, and makes a choice. They are a private company afterall, one that does a few US government flights every year as well.
John,A picture (or video) is worth a thousand words, so I give you this...
With respect, unless I am very mistaken, the release of pressurized gas would result in adiabatic cooling, not heating. Boyle's law, etc. As the pressure of a mass of air is decreased, it cools.
Please let me know if I'm missing something.
John,A picture (or video) is worth a thousand words, so I give you this...
With respect, unless I am very mistaken, the release of pressurized gas would result in adiabatic cooling, not heating. Boyle's law, etc. As the pressure of a mass of air is decreased, it cools.
Please let me know if I'm missing something.
What would be the initial speed of a LOX front decompressing from structural failure at S2's pressures? Couldn't this front have started at 2000-5000 ft/s and slowed down to 1/10th of that, from the aforementioned air drag, until reaching the deflagration speed you point out? (Not rhetorical questions, I really couldn't say, but those would speak against an external powerful event)
No. Good point - and a probable answer to the flight pressurization level...John,A picture (or video) is worth a thousand words, so I give you this...
With respect, unless I am very mistaken, the release of pressurized gas would result in adiabatic cooling, not heating. Boyle's law, etc. As the pressure of a mass of air is decreased, it cools.
Please let me know if I'm missing something.
Does that happen at 30 psi or so?
What would be the initial speed of a LOX front decompressing from structural failure at S2's pressures? Couldn't this front have started at 2000-5000 ft/s and slowed down to 1/10th of that, from the aforementioned air drag, until reaching the deflagration speed you point out? (Not rhetorical questions, I really couldn't say, but those would speak against an external powerful event)
Oh great, an easy question.
No easy answers.
It has an expansion ratio of 1:861 (not densified) which means it wants to create lots of volume once it's boiled off, but how fast it goes from liquid to gas depends on a ton of other things.
I can picture developing a software simulation to give a range of answers your question inside of a week.
What would be the initial speed of a LOX front decompressing from structural failure at S2's pressures? Couldn't this front have started at 2000-5000 ft/s and slowed down to 1/10th of that, from the aforementioned air drag, until reaching the deflagration speed you point out? (Not rhetorical questions, I really couldn't say, but those would speak against an external powerful event)
Oh great, an easy question.
No easy answers.
It has an expansion ratio of 1:861 (not densified) which means it wants to create lots of volume once it's boiled off, but how fast it goes from liquid to gas depends on a ton of other things.
I can picture developing a software simulation to give a range of answers your question inside of a week.
What would be the initial speed of a LOX front decompressing from structural failure at S2's pressures? Couldn't this front have started at 2000-5000 ft/s and slowed down to 1/10th of that, from the aforementioned air drag, until reaching the deflagration speed you point out? (Not rhetorical questions, I really couldn't say, but those would speak against an external powerful event)
Oh great, an easy question.
No easy answers.
It has an expansion ratio of 1:861 (not densified) which means it wants to create lots of volume once it's boiled off, but how fast it goes from liquid to gas depends on a ton of other things.
I can picture developing a software simulation to give a range of answers your question inside of a week.
Occam's razor says that the noises are more likely to originate within the junkyard in which the videographer was located. This was discussed upthread.
Please don't post your personal theories multiple times. We saw them the first time. If you didn't get a response it's because we didn't think it credible, or interesting, it sufficiently different from the last person who posted that theory.
One theory post per person, please.
ok, Mr Occam, there are NO extraneous noises from said junkyard the minute plus prior to the explosion other than birds and bugs.
was this camera manned at the time or remote operated? was said junkyard manned or occupied during this test? was the *Ploink* the camera operator standing up when he/she saw the flash?
Ask Mr Occam to discuss Correlation not being causation? It cuts both ways, just because there is a junkyard doesn't necessarily mean it is in use and occupied during a static test. unless JIM can verify it's occupancy. some of us have jobs and can't be glued to NSF all day. Thanks Kabloona!
... an overpressure in the O2 tank should have been relieved by venting which should have at least slowed it down and would probably have had other visual cues. That leads me to think it was an underpressure in the RP-1 tank. This could be caused by a single spurious valve opening. That could be GSE, but is likely the rocket.
From SpaceX's website (http://www.spacex.com/news/2016/09/01/anomaly-updates)QuoteSeptember 2, 6:45pm EDT
SpaceX has begun the careful and deliberate process of understanding the causes and fixes for yesterday's incident. We will continue to provide regular updates on our progress and findings, to the fullest extent we can share publicly.
We deeply regret the loss of AMOS-6, and safely and reliably returning to flight to meet the demands of our customers is our chief priority. SpaceX's business is robust, with approximately 70 missions on our manifest worth over $10 billion. In the aftermath of yesterday's events, we are grateful for the continued support and unwavering confidence that our commercial customers as well as NASA and the United States Air Force have placed in us.
Overview of the incident:
- Yesterday, at SpaceX's Launch Complex 40 at Cape Canaveral Air Force Station, an anomaly took place about eight minutes in advance of a scheduled test firing of a Falcon 9 rocket.
- The anomaly on the pad resulted in the loss of the vehicle.
- This was part of a standard pre-launch static fire to demonstrate the health of the vehicle prior to an eventual launch.
- At the time of the loss, the launch vehicle was vertical and in the process of being fueled for the test. At this time, the data indicates the anomaly originated around the upper stage liquid oxygen tank. Per standard operating procedure, all personnel were clear of the pad. There were no injuries.
To identify the root cause of the anomaly, SpaceX began its investigation immediately after the loss, consistent with accident investigation plans prepared for such a contingency. These plans include the preservation of all possible evidence and the assembly of an Accident Investigation Team, with oversight by the Federal Aviation Administration and participation by NASA, the United States Air Force and other industry experts. We are currently in the early process of reviewing approximately 3000 channels of telemetry and video data covering a time period of just 35-55 milliseconds.
As for the Launch Pad itself, our teams are now investigating the status of SLC-40. The pad clearly incurred damage, but the scope has yet to be fully determined. We will share more data as it becomes available. SpaceX currently operates 3 launch pads – 2 in Florida and 1 in California at Vandenberg Air Force Base. SpaceX's other launch sites were not affected by yesterday's events. Space Launch Complex 4E at Vandenberg Air Force Base is in the final stages of an operational upgrade and Launch Complex 39A at Kennedy Space Center remains on schedule to be operational in November. Both pads are capable of supporting Falcon 9 and Falcon Heavy launches. We are confident the two launch pads can support our return to flight and fulfill our upcoming manifest needs.
Again, our number one priority is to safely and reliably return to flight for our customers, as well as to take all the necessary steps to ensure the highest possible levels of safety for future crewed missions with the Falcon 9. We will carefully and thoroughly investigate and address this issue.
Empty junk yards when there's a breeze blowing can produce all kinds of weird noises. Trust me. I know this.Additionally, people near the camera who see a very large explosion that might be uncomfortably close may well bump into things while deciding what to do before the blast/noise/fragments arrive.
So according to the above notice, the event occurred around T minus 8 minutes. These processes would be occurring around that time on the pre-launch check list:
T-0:10:00 Stage 2 Venting for LOX Fast Fill
T-0:09:50 Flight Software Final Setups complete
T-0:09:45 TEA-TEB Ignition System Setup
T-0:09:45 Stage 2 Transmitter Re-Activation
T-0:09:30 M1D Trim Valve Cycling
T-0:09:15 Stage 1 Helium Topping
T-0:07:45 MVac Fuel Trim Valve Setup
T-0:07:30 Engine Chill Readiness
T-0:07:00 Engine Chilldown (Bleed Valves Open, both Stages
T-0:07:00 Spacecraft on Internal Power
It is also understood that the Static Fire was used to evaluate new techniques for launch window management which had become a challenge when Falcon 9 FT was introduced, given the strong desire to avoid the sub-cooled Liquid Oxygen to warm up during holds in the count.so I wouldn't be surprised if this wasn't the exact sequence/timing they followed during this static fire..
A brief window for holding exists in the final countdown minutes prior to engine chilldown, but SpaceX was aiming to expand this capability to take advantage of longer windows such as JCSat’s two-hour launch slot.
Looking hard at the pictures posted by hartspace and John Allen, it appears that the cradle just under the payload fairing is actuated by a hydralic cylinder with 2 black curved lines (hoses?) going back into the interior of the strongback. The anomaly happened close to the time the cradle should have been retracted. Is it possible that a ruptured hydralic line sent a mist of fluid into the oxygen rich environment below?
Around T-8 mins, huh.
That would imply quite an incomplete LOX load, 1/4 to 1/5 of the tank might still have been empty and the tanks probably (?) weren't pressurized.
What would be the initial speed of a LOX front decompressing from structural failure at S2's pressures? Couldn't this front have started at 2000-5000 ft/s and slowed down to 1/10th of that, from the aforementioned air drag, until reaching the deflagration speed you point out? (Not rhetorical questions, I really couldn't say, but those would speak against an external powerful event)
Oh great, an easy question.
No easy answers.
It has an expansion ratio of 1:861 (not densified) which means it wants to create lots of volume once it's boiled off, but how fast it goes from liquid to gas depends on a ton of other things.
I can picture developing a software simulation to give a range of answers your question inside of a week.
Actually just one. Assuming the Lox is sub-cooled (not boiling at one atmosphere of pressure), gas generation is a simple function of energy input. 213 kJ/kg.
Quick question: is there a hydraulic system on S2? I know S1 has one, and it's an open system that uses RP-1 as the working fluid and drains into the main RP-1 tank. If S2 also has a similar setup, the S2 hydraulic tanks, or the umbilicals for filling them, would be good candidates.
Around T-8 mins, huh.
That would imply quite an incomplete LOX load, 1/4 to 1/5 of the tank might still have been empty and the tanks probably (?) weren't pressurized.
If practicing the hold, possibly little to no Lox was loaded.
Don't the Lox fills run with tank vented to atmosphere?
Around T-8 mins, huh.
That would imply quite an incomplete LOX load, 1/4 to 1/5 of the tank might still have been empty and the tanks probably (?) weren't pressurized.
Crank up the volume, the first sound could be the creak of metal bending. If that's the case, we might be hearing a strut bend and break, a COPV rupturing or helium hose popping, and the loud boom is the visible explosion.
Please... This is an incessant problem on the internet to attribute new failures to previous issues. In engineering its the exception rather than the rule that a new failure is the same failure as before. If something fails its almost certainly something else that failed unless your engineers have no clue what they're doing or root cause was not found. This failure is NOT going to be related to struts. Forget the struts exist. That's a solved problem. Different metal suppliers, different stronger design, additional struts, impossible to be the same problem.
I dunno, ever heard of Taurus, OCO, and Glory? Just saying...
Around T-8 mins, huh.
That would imply quite an incomplete LOX load, 1/4 to 1/5 of the tank might still have been empty and the tanks probably (?) weren't pressurized.
I'm a bit late, but notably for Taurus they never found root cause, thus what I said.
Suppose there is an major electrical fault that results in an arc being struck at that point...
Why... is not the question... the question is the outcome...
There are not those types of voltages and amperages used on the vehicle. Voltage is around 28
I don't think that's appropriate. It's not a launch failure, so it's not a launch failure. It was a testing failure, which led to destruction of the vehicle and also the payload because SpaceX shortsightedly (I almost want to say "foolishly") put it way too close.Yeah, that's how I've got it in my SpaceX launches spreadsheet.JCM how do you classify this event? A payload and rocket were lost at the launch pad but it wasn't a launch failure as it wasn't a launch attempt. Watching your website to see how you classify it as it is probably the launch log of choice on the web
I'm not JCM, but do my own tracking of launches. Even though the payload was lost in a prelaunch exercise, it counts as a failure in my book. You don't necessarily have to distinguish between a launch failure or a ground failure. But it's a fact that the vehicle failed to get the payload to orbit. It's not like the vehicle failed without the payload and you just get a new booster and have a successful mission a few months later.
Suppose there is an major electrical fault that results in an arc being struck at that point...
Why... is not the question... the question is the outcome...
There are not those types of voltages and amperages used on the vehicle. Voltage is around 28
What about spacecraft battery charging. Don't those go over a hundred?
...This is pretty obvious, now. I don't think anyone should disagree with this.
But the debate is not whether or they should perform static fires. The debate is whether the spacecraft should be mated during the test. And this event has shown that they chose the wrong tradeoff. Risking a multi hundred million spacecraft to save a couple days is not smart....
SpaceX hasn't launched 40 Falcon 9s. Heck, this would've been only the 9th full thrust. They're still tweaking for fast fill of deeply subcooled propellants, a fact that probably contributed to the failure.
There is a principle in manufacturing that basically goes, the first 40 systems you build are all prototypes. You tend to declare that you know how to do manufacturing after 10 or so, but you're wrong. Dead wrong.
Things break. If you can to that 40 mark, you actually have manufacturing processes that show promise, but anything less, it's all custom.
Elon fell for complacency again.
Software engineering is not the same as hardware engineering.
It's not that space is hard, or rockets are hard, it's that going from concept to production is hard, and if you assume you know what you're doing before you hit the numbers that translate into production, you get screwed.
Not true. They are all prototypes. Rockets are constantly evolving. There are subtle improvements, part changes due to obsolesce, etc.
Falcon 9 has gone through 2 upgrades that drastically changed the vehicle.
It IS that space is hard and rockets are hard because the environment is unforgiving.
Aircraft do not constantly evolve nor are they all prototypes.
A current model Cessna is not a prototype. If it were, the FAA would only let it fly with an experimental license.
Elon want's to become a transportation company with a reliable reusable launcher. Such a device is not a prototype. It's a production model built on the same assembly line as the next 300 - 3,000 models.
As long as the answer is that it's a prototype, it's an at risk device of unknown reliability.
I contend that a prototype is a risk until you cease doing "upgrades" and build the same thing at least 40 times.
Otherwise, you're just waiting for the next RUD excuse. "Thank you for our forgiving customers, we'll get you back to flight in 4-6 months... until we have the next RUD." That's how you kill a company.
Space is forgiving if you have it nailed, otherwise, it nails you. Elon hasn't learned that lesson yet.
SpaceX could've stopped with the Falcon 9 v1.0, but then they couldn't have launched this payload at all.
They also could've tried to make a go out of Falcon 1 instead of pushing for COTS (and thus Falcon 9 and Dragon). They could've avoided reuse.
But they haven't. SpaceX wouldn't be where they are today without these significant improvements. They wouldn't be groundbreaking with reuse, they wouldn't be planning a trip to Mars in a couple years, and they sure as heck wouldn't be laying the groundwork for a space transportation architecture with the potential for actually colonizing Mars. Yes, they could've chosen the clear, safe course that leads ever downward into stagnation.
And a thing about Elon: he knows this is a risky path to take. He's well aware that it's risky and that SpaceX could fail.
I have seen this discussed briefly, but any thoughts on it being the same issue as with the CRS-7 failure? A faulty steel strut, while certainly possible, just doesn't seem like the type of thing you could be 100% certain about. I am sure SpaceX ruled out all other possible alternatives that they could think of, but that doesn't mean that it is impossible for them to miss something. Maybe some kind of design flaw with the second stage that has been problematic on multiple occasions?
Not COPV or FTS. Explosion is an external air burst. No debris until much later, other than the big cap-like thing that's shot straight up and tumbles.
Maybe a crack in the unconstrained S curve of this line (see attached) especially if that's the RP-1 line. High pressure though the crack or pinhole would make an aerosol. A line in that acoustic environment shouldn't have an unconstrained S.
ANOTHER reason you might be right. The detonation profile appears to be taller than wider. If RP-1 was becoming an aerosol, being heavier than air, the aerosol would be sinking over time, which would make a detonation cross section that's taller than wider.
I'm a bit late, but notably for Taurus they never found root cause, thus what I said.
Yes, they did.
Using this data, the MIB was able to analyze and determine that the proximate cause of
the mishap was the failure of the payload fairing system to separate. Detailed analysis
determined one of the side rails of the payload fairing system failed to fully fracture near
the fairing’s nose cap. However, no root cause for the fairing’s failure to separate was
able to be determined.
The OCO T8 mishap investigation could not identify a root cause but did identify four potential intermediate causes:
1. Failure of the base ring frangible joint to completely fracture.
2. Failure of the electrical subsystem preventing ordnance from firing.
3. Failure of the fairing’s hot gas generator pneumatic system to pressurize resulting in a failure to push the fairing halves and/or side rails apart.
4. Snagging of the flexible confined detonating cord (FCDC) on one of the payload fairing side rail’s nut plate.
I'm a bit late, but notably for Taurus they never found root cause, thus what I said.
Yes, they did.
They didn't find the root cause of the fairing separation failure before Glory launched. They found that the fairing didn't separate, but that's not a root cause. This is well known. If I'm wrong please point out information counter to that.
I'm a bit late, but notably for Taurus they never found root cause, thus what I said.
Yes, they did.
They didn't find the root cause of the fairing separation failure before Glory launched. They found that the fairing didn't separate, but that's not a root cause. This is well known. If I'm wrong please point out information counter to that.
IIRC, they did eventually find that the material heat treat (or some other metallurigcal condition) on the frangible joint hadn't been properly controlled. But that was only after two fairing sep failures, by which time it was too late.
Ultimately, I think ignoring the AMOS-6 incident would be discarding valid data about the reliability of the rocket.
snip
Ultimately, I think ignoring the AMOS-6 incident would be discarding valid data about the reliability of the rocket.
The only thing I would say about this would be to wait until the cause of the accident was found. If it happened to be something on the TEL that caused damage to the rocket and the subsequent LOV, that wouldn't be the rockets fault and should have no impact on the calculated "reliability".
What would you guys consider this as if the event that cause LOV wasn't rocket related?
Ultimately, I think ignoring the AMOS-6 incident would be discarding valid data about the reliability of the rocket.
The only thing I would say about this would be to wait until the cause of the accident was found. If it happened to be something on the TEL that caused damage to the rocket and the subsequent LOV, that wouldn't be the rockets fault and should have no impact on the calculated "reliability".
What would you guys consider this as if the event that cause LOV wasn't rocket related?
As you can see, it pretty significantly impacts the credible range of expected reliability, but the credible range is still pretty wide since the launch vehicle has limited history. I'm sticking with including AMOS-6 as a failure though.
Ultimately, I think ignoring the AMOS-6 incident would be discarding valid data about the reliability of the rocket.
The only thing I would say about this would be to wait until the cause of the accident was found. If it happened to be something on the TEL that caused damage to the rocket and the subsequent LOV, that wouldn't be the rockets fault and should have no impact on the calculated "reliability".
What would you guys consider this as if the event that cause LOV wasn't rocket related?
Ultimately, I think ignoring the AMOS-6 incident would be discarding valid data about the reliability of the rocket.
The only thing I would say about this would be to wait until the cause of the accident was found. If it happened to be something on the TEL that caused damage to the rocket and the subsequent LOV, that wouldn't be the rockets fault and should have no impact on the calculated "reliability".
What would you guys consider this as if the event that cause LOV wasn't rocket related?
Yes, the pad is part of the system
snip
I believe you've not included the CRS-7 failure.
Ultimately, I think ignoring the AMOS-6 incident would be discarding valid data about the reliability of the rocket.
The only thing I would say about this would be to wait until the cause of the accident was found. If it happened to be something on the TEL that caused damage to the rocket and the subsequent LOV, that wouldn't be the rockets fault and should have no impact on the calculated "reliability".
What would you guys consider this as if the event that cause LOV wasn't rocket related?
Ultimately, I think ignoring the AMOS-6 incident would be discarding valid data about the reliability of the rocket.
The only thing I would say about this would be to wait until the cause of the accident was found. If it happened to be something on the TEL that caused damage to the rocket and the subsequent LOV, that wouldn't be the rockets fault and should have no impact on the calculated "reliability".
What would you guys consider this as if the event that cause LOV wasn't rocket related?
On that note, is there precedence for a loss of a rocket which is completely the fault of GSE? I looked at Jonathan McDowell's list of rocket losses pre-launch he posted on Twitter, and he lists Atlas Able 9C (1959), R-16 (1960), Vostok (1980), VLS-1 (2003), and VS40M (2015). I also found a few others, such as Kosmos-3M (1973).
I couldn't always find a lot of details, but they all seemed to have various causes aside from 'ground equipment'. Granted, there's not much detail, but there always seems to be other causes.
It isn't 27/29. F9FT is not the same as the V1.1 or V1.0
You won't find a failure due to GSE because nobody puts the spacecraft at risk like Spacex did
You won't find a failure due to GSE because nobody puts the spacecraft at risk like Spacex did
Let's say "usually don't" not "don't".
https://www.youtube.com/watch?v=AUHLdJsoUOE
Would you also include Atlas III along with the Atlas V?It isn't 27/29. F9FT is not the same as the V1.1 or V1.0
I've mentioned this in the dedicated post I created for my rocket reliability estimates elsewhere. I completely agree, the FT is not the same as V1.0 or V1.1. That said, I include it because their reliability is still highly correlated with the FT, even if they are not fully equal. It's really a trade off of accuracy for precision. Without including prior versions, the Falcon 9 FT's estimate would cover a significantly larger range of potential true values of reliability, but would be more likely to include the true value within that range. I also combine all variants of other rockets for the same reason. Otherwise the credible interval becomes so large (and the precision so low) that it is essentially useless, even if it is technically more accurate. I've attached the estimate for the Falcon 9 FT by itself so that you can see the impact it has on the estimate.
I'm sticking with including AMOS-6 as a failure though.It is clearly a "failure", though not a "launch failure". It falls into the same category as Thor 103, Atlas 9C/Able, the 3/18/80 pad explosion of Vostok-2M at Plestesk, and even Soyuz-U/Soyuz T-10-1. Not to mention the first Falcon 1 flight article, which was destroyed during on-pad testing accidents prior to the first launch. If you count F9-29 in the overall performance scheme, you also have to count the first Falcon 1 that never flew. There was also at least one prior damaged or destroyed Falcon 9 stage if I recall correctly.
Would you also include Atlas III along with the Atlas V?
It is clearly a "failure", though not a "launch failure"
...
I consider Falcon 9 v1.2 at eight flights with no launch failures, but with a ninth vehicle and its payload destroyed and launch pad heavily damaged in a ground test accident
Would you also include Atlas III along with the Atlas V?It isn't 27/29. F9FT is not the same as the V1.1 or V1.0
I've mentioned this in the dedicated post I created for my rocket reliability estimates elsewhere. I completely agree, the FT is not the same as V1.0 or V1.1. That said, I include it because their reliability is still highly correlated with the FT, even if they are not fully equal. It's really a trade off of accuracy for precision. Without including prior versions, the Falcon 9 FT's estimate would cover a significantly larger range of potential true values of reliability, but would be more likely to include the true value within that range. I also combine all variants of other rockets for the same reason. Otherwise the credible interval becomes so large (and the precision so low) that it is essentially useless, even if it is technically more accurate. I've attached the estimate for the Falcon 9 FT by itself so that you can see the impact it has on the estimate.
I'm sticking with including AMOS-6 as a failure though.It is clearly a "failure", though not a "launch failure". It falls into the same category as Thor 103, Atlas 9C/Able, the 3/18/80 pad explosion of Vostok-2M at Plestesk, and even Soyuz-U/Soyuz T-10-1. Not to mention the first Falcon 1 flight article, which was destroyed during on-pad testing accidents prior to the first launch. If you count F9-29 in the overall performance scheme, you also have to count the first Falcon 1 that never flew. There was also at least one prior damaged or destroyed Falcon 9 stage if I recall correctly.
I consider Falcon 9 v1.2 at eight flights with no launch failures, but with a ninth vehicle and its payload destroyed and launch pad heavily damaged in a ground test accident.
- Ed Kyle
A more impartial adjustment would be to weigh older launches less than recent ones via an exponential decay. This would count more recent events as more important in the reliability assessment, and make it less sensitive to including older variants. That would let us move on to arguing about decay rates instead.
With its launch pad likely facing major repairs, SpaceX said it would use a second Florida site, called 39A, which is located a few miles north at NASA’s Kennedy Space Center and was used for space shuttle missions.
The pad is on schedule to be operational in November, SpaceX said. The company had planned to use the pad for the first time later this year for a test flight of its new Falcon Heavy rocket.
SpaceX hasn't launched 40 Falcon 9s. Heck, this would've been only the 9th full thrust. They're still tweaking for fast fill of deeply subcooled propellants, a fact that probably contributed to the failure.
There is a principle in manufacturing that basically goes, the first 40 systems you build are all prototypes. You tend to declare that you know how to do manufacturing after 10 or so, but you're wrong. Dead wrong.
Things break. If you can to that 40 mark, you actually have manufacturing processes that show promise, but anything less, it's all custom.
Elon fell for complacency again.
Software engineering is not the same as hardware engineering.
It's not that space is hard, or rockets are hard, it's that going from concept to production is hard, and if you assume you know what you're doing before you hit the numbers that translate into production, you get screwed.
Not true. They are all prototypes. Rockets are constantly evolving. There are subtle improvements, part changes due to obsolesce, etc.
Falcon 9 has gone through 2 upgrades that drastically changed the vehicle.
It IS that space is hard and rockets are hard because the environment is unforgiving.
Aircraft do not constantly evolve nor are they all prototypes.
A current model Cessna is not a prototype. If it were, the FAA would only let it fly with an experimental license.
Elon want's to become a transportation company with a reliable reusable launcher. Such a device is not a prototype. It's a production model built on the same assembly line as the next 300 - 3,000 models.
As long as the answer is that it's a prototype, it's an at risk device of unknown reliability.
I contend that a prototype is a risk until you cease doing "upgrades" and build the same thing at least 40 times.
Otherwise, you're just waiting for the next RUD excuse. "Thank you for our forgiving customers, we'll get you back to flight in 4-6 months... until we have the next RUD." That's how you kill a company.
Space is forgiving if you have it nailed, otherwise, it nails you. Elon hasn't learned that lesson yet.
SpaceX could've stopped with the Falcon 9 v1.0, but then they couldn't have launched this payload at all.
They also could've tried to make a go out of Falcon 1 instead of pushing for COTS (and thus Falcon 9 and Dragon). They could've avoided reuse.
But they haven't. SpaceX wouldn't be where they are today without these significant improvements. They wouldn't be groundbreaking with reuse, they wouldn't be planning a trip to Mars in a couple years, and they sure as heck wouldn't be laying the groundwork for a space transportation architecture with the potential for actually colonizing Mars. Yes, they could've chosen the clear, safe course that leads ever downward into stagnation.
And a thing about Elon: he knows this is a risky path to take. He's well aware that it's risky and that SpaceX could fail.
God bless his dreams.
Manufacturability isn't a dream, it's an engineering issue.
From my point of view, his risky path is ready to kill SPACEX which I would be mortified to see.
However, knowing the risks, without knowing the probabilities associated with risks is a path to failure.
IMHO, this RUD was avoidable. Totally. Whatever the cause.
That's what irritates me most. He doesn't have to stop his dream or his testing or striving for the new-age of humanity. That's what makes him great.
He could, however, recognize the engineering challenges which would let him succeed.
ANY manufacturing engineer could have predicted a failure soon, this one, or another, except those manufacturing engineers are 40-60 years old, and won't move to L.A. at any price. His brilliant kids don't have the experience to know to ask what could go wrong. They haven't failed before.
Elon has a cult more than a team, and he needs a team.
After this issue is resolved, he resets to zero, and my 40 count restarts. If we're all lucky, he'll get it. If we're not, we'll go another 20 +- launches before the next surprise.
You won't find a failure due to GSE because nobody puts the spacecraft at risk like Spacex didDoes anybody else do a static fire (which greatly reduces the launch risk) like SpaceX does?
Given the huge amounts of money at stake in any given launch in the commercial satellite industry, customers place a high premium on both reliability and cheap launches. For the moment, and in the historical context of spaceflight, Thursday's explosion probably won't tarnish SpaceX on the reliability front enough to overcome its advantages on the efficiency front.
Why did they fuel the upper stage before they test fired the first stage? It doesn't seem necessary, the small upper stage could be fueled rather quickly after the first stage has been tested. Seems as if it would've avoided this accident.
Occam's razor says that the noises are more likely to originate within the junkyard in which the videographer was located. This was discussed upthread.
Please don't post your personal theories multiple times. We saw them the first time. If you didn't get a response it's because we didn't think it credible, or interesting, it sufficiently different from the last person who posted that theory.
One theory post per person, please.
ok, Mr Occam, there are NO extraneous noises from said junkyard the minute plus prior to the explosion other than birds and bugs.
was this camera manned at the time or remote operated? was said junkyard manned or occupied during this test? was the *Ploink* the camera operator standing up when he/she saw the flash?
Ask Mr Occam to discuss Correlation not being causation? It cuts both ways, just because there is a junkyard doesn't necessarily mean it is in use and occupied during a static test. unless JIM can verify it's occupancy. some of us have jobs and can't be glued to NSF all day. Thanks Kabloona!
> AC
The line with the S curve is insulated for cryogenic supply, either LOX or chilled RP-1. In other images, one of the large stage 1 umbilicals comes directly off of it. Looks like it's part of the LOX supply, with the bigger diameter pipe to the left being for oxygen gas return. The bigger pipe splits and also goes to a vent at the top of the strongback.
Large cryogenic supplies are typically a loop, because the pipe has to be chilled before liquid can flow through safely / reasonably. Its chilled by first pumping cold gas, recirculating the gas through a return pipe to a refrigerator that drives the temperature lower over time.
There is pressurized fuel and oxidizer in the supply lines all the way through liftoff.
Goes without saying that we're all hoping for a safe return to flight as soon as possible.
I'll bet we see a big new claw at the top of the strongback. Big enough to hold the payload. =/
There's certainly no consensus that static fires reduce risk. Some, in fact, believe it can hasten a failure that otherwise wouldn't have occurred.You won't find a failure due to GSE because nobody puts the spacecraft at risk like Spacex didDoes anybody else do a static fire (which greatly reduces the launch risk) like SpaceX does?
Out of curiosity: what "primary event" are you suggesting imparted such a phenomenal force to the (large) piece, that you claim overshadows the powerful burst+explosion acceleration?
The primary event occurs during Frame 1 of the explosion video sequence. From Frame 0 where everything is fine, Frame 1 shows a measurable pixel saturation region of roughly 35 feet horizontal and 85 feet vertical. That's an explosion with a wave front between 2,000 and 5,000 feet per second, depending on when it started during the integration time of the CCD or whatever the camera used. A fuel air explosive would go about 5,000 feet per second. TNT would go about 19,000 feet per second. That first frame shows an explosion propagating at 2 to 5 times the speed of sound. That to me is the "primary" event.
After frame 1, the fireball growth is significantly slower, which by Frame 4 includes the tank rupture explosion, which piddles along at maybe 100-200 feet per second. That's to me, the secondary event.
You won't find a failure due to GSE because nobody puts the spacecraft at risk like Spacex didDoes anybody else do a static fire (which greatly reduces the launch risk) like SpaceX does?
Indeed. Testing with the payload mounted actually doubles part of the risk of losing the payload. It's not really a test anymore.Why did they fuel the upper stage before they test fired the first stage? It doesn't seem necessary, the small upper stage could be fueled rather quickly after the first stage has been tested. Seems as if it would've avoided this accident.
Mostly, I think it was for mass and vibration attenuation. The empty tanks of the second stage would flex far more than full tanks and likely would have buckled. They would also not likely been able to properly support the payload during the test. The mass issue gives the rocket as a whole, a more realistic profile as a whole for the test.
Although, to be honest, I'm surprised that for the test, they didn't use a mass simulator in place of the actual payload.
For a full on dry test, I could understand it, but for a full on engine test, that seems a bit odd.
Some video of COPV failures. Attached is a paper on COPV failures. A possible, but I think very unlikely cause of a COPV failure is procedural error. If the cryo Helium is loaded before significant LOX loading, the Helium might heat up and over pressurise the tank, causing an explosion. Another possible cause is a tank defect. I would think SpaceX would know about these possible causes and have taken preventative measures, for example interlocks to prevent early cryo Helium loading and testing of the tanks before use. It will be interesting to find out what really caused this failure.
https://www.youtube.com/watch?v=5UdVnO10J3U
The failure does appear to have originated from the TE/strongback vs the LV.
I wonder if it may have been damaged during the last flight.
F9 v1.2 has more thrust then v1.1 and was the pad hardware change to deal with this?
Does anyone else notice the sounds in the video...
You won't find a failure due to GSE because nobody puts the spacecraft at risk like Spacex did
Let's say "usually don't" not "don't".
Yes, because they share a good deal of components, including the upper stage and engine, their reliability should be highly correlated and so I include them as one launch system. That said, the Atlas III has very few launches compared to the Atlas V, and the Atlas V has a very, very good track record, so the difference is minimal.
Why did they fuel the upper stage before they test fired the first stage? It doesn't seem necessary, the small upper stage could be fueled rather quickly after the first stage has been tested. Seems as if it would've avoided this accident.
You won't find a failure due to GSE because nobody puts the spacecraft at risk like Spacex didDoes anybody else do a static fire (which greatly reduces the launch risk) like SpaceX does?
Out of curiosity: what "primary event" are you suggesting imparted such a phenomenal force to the (large) piece, that you claim overshadows the powerful burst+explosion acceleration?
The primary event occurs during Frame 1 of the explosion video sequence. From Frame 0 where everything is fine, Frame 1 shows a measurable pixel saturation region of roughly 35 feet horizontal and 85 feet vertical. That's an explosion with a wave front between 2,000 and 5,000 feet per second, depending on when it started during the integration time of the CCD or whatever the camera used. A fuel air explosive would go about 5,000 feet per second. TNT would go about 19,000 feet per second. That first frame shows an explosion propagating at 2 to 5 times the speed of sound. That to me is the "primary" event.
After frame 1, the fireball growth is significantly slower, which by Frame 4 includes the tank rupture explosion, which piddles along at maybe 100-200 feet per second. That's to me, the secondary event.
Most of the saturated area is reflected light. There was a tremendously bright small event that caused everything around it to reflect all that light. You can see the velocity of the expansion cloud is much slower than that. You can also see several projectiles (I count 4) that lead the expansion cloud that likely originate from the explosion site. (2 pieces shoot downward, one shoots left but only appears for two frames and one shoots right. The two that shoot down are most visible.)
Does anyone else notice the sounds in the video <snip> at 1:16 and 1:19. At a little past 1:16 there is an odd high pitched noise followed by a lower pitched noise at 1:19 that is reminiscent of metal bending. These could be just local noises around where the camera was or more interesting if they did come from the rocket.
Sound from the first conflagration reaches the camera at 1:23.
Most of the saturated area is reflected light. There was a tremendously bright small event that caused everything around it to reflect all that light. You can see the velocity of the expansion cloud is much slower than that. You can also see several projectiles (I count 4) that lead the expansion cloud that likely originate from the explosion site. (2 pieces shoot downward, one shoots left but only appears for two frames and one shoots right. The two that shoot down are most visible.)
Wow! you make me feel blind. Totally missed the other fragments. :)
Below are Frame 1 and Frame2 composited with the first fragment superimposed. It vanishes by Frame3.
Linear trajectory assumption.
The black lines indicate the horizontal distance traveled if equal to the prior frame.
However, since there is no explosion in Frame0, the actual origin is somewhere to the right.
Whatever it is is moving an average of 1,000 feet per second.
The question would be, what's along the indicated red line?
Does anyone else notice the sounds in the video
Your explanation and diagram don't make sense to me.
The question would be, what's along the indicated red line?
Post the two separate frames
I'm sorry if it was discussed already, but does anyone has any hypothesis in regard to the second explosion, the one at 3:42 in the video?I don't have the video handy, but my recollection is that the explosions are as follows:
That could be something blasted from the back of the erector by the shockwave of the initial explosion.
For reference, it might be in the next frame too. Under enhancement there might be something in the 3rd frame. If so, its on the same trajectory line, but moved only 1/4 of the previous distance, and is dim. It could also be a jpeg/mpeg artifact. I'll post if I get confident that it's real.
Your explanation and diagram don't make sense to me.
OK, you see something in two frames at different locations. You assume they are moving from an origin.
You connect the two points with a red line. If there are no other factors, that line describes a possible trajectory of where the object was, or will be, in time.
You measure the horizontal distance between the two known object locations (black line on the right). You duplicate it and place it an equal distance to the left, along the possible trajectory red line.
That gives you a first approximation of where that object was an equal time prior, provided the speed and trajectory do not change.
Where the bottom black line intersects the red trajectory line is a 1st approximation of where that part came from.
That might indicate where the initiating event occurred.
Hence the question, what's at the intersection of the bottom black line and the red line? Whatever is there becomes suspect.
There are a few problems with identifying what these objects are, no least that the video gives no idea of what their motion is like in the plane aligned with the view from the camera - i.e. you can't easily tell how much of their motion is towards (or away from) the camera.
There seems to be a (slight!) consensus that the initial explosion occurred outside the vehicle (whether of not caused by gas leaking from within), in which case some of the early material ejected will have been parts of the erector and associated equipment - and that makes identifying the cause of the explosion essentially impossible with just this one long-distance camera viewpoint.
Yes but the black lines aren't needed. Just draw a straight line between the two points (and the following points). I don't see why you'd draw horizontal lines there.
WRT to the exemplar object that you commented on, if it is in Frame3, then it's undergoing deceleration, which in principle could put its origin further left on the red line, rather than right if it were constant velocity.
You're right, we only have X-Y measurements, no Z, with the possible exception of the thingee.
However, tracing to the origin of the various fragments would constrain the X-Y origin.
Jim seems certain that the "cause" isn't along the line I drew. Is there a difference between the "cause" of the event, and the first explosion's location?
Yes but the black lines aren't needed. Just draw a straight line between the two points (and the following points). I don't see why you'd draw horizontal lines there.
Assume constant velocity (which is probably wrong), then the horizontal distance traveled between any two frames will be the same.
The right black line indicates the horizontal distance traveled for the two frames showing the object.
The red line indicates the inferred trajectory forward and backward in time.
If you want to know where the object was in the previous frame, given the above assumptions, you copy the length of the right black line.
You align the right hand side of the copy with the frame 1 location which indicates the horizontal distance in may have traveled from the previous frame.
Slide the yard stick (left black line) down until the left edge intersects the trajectory line.
With these assumptions, that now indicates a unique point where the part may have previously been.
That could be something blasted from the back of the erector by the shockwave of the initial explosion.
It's bright, but that's likely to be just reflection of the explosion.
Jim - out of interest, do you know what is the white bit of equipment in the image attached?
Part of the test is tanking both stages and going through the standard countdown. The vehicle never flies with the upper stage empty so firing the booster with it empty is an unknown and unflight like condition.
Anyone have any info of the temperature differential of the loaded RP-1 and LOX? My thinking is along the lines of a stress fracture at the interface at the common bulkhead that I mentioned originally a couple of days back. A material "snap" failure would provide the energy and the prop mixing rapidly. That could account for the initial detonation and ensuing deflagration.
Also super chilled lox (66k) condenses nitrogen out of air. Not that that would affect the anomaly.
Also super chilled lox (66k) condenses nitrogen out of air. Not that that would affect the anomaly.
More importantly, it condenses oxygen out of air (unless insulated), which has been observed on walls of uninsulated liquid hydrogen tanks. So there might be liquid oxygen in places where it should not be, without any leaks. Although I trust SpaceX took care to insulate everything.
What says there is any condensed O2?
Assuming an rp1 leak from somewhere there is breeze of about 2-3mph at the time, enough to spread an rp1/lox aerosol mixture without dispersing it.
Note deflagration on the retracted Strongarm in the same place as that supposed for this event.
Let's just stop with the external explosion idea. There is nothing that excludes internal explosion or rupture.
Anyways, anything on the outside is just going to flash and not going to be an explosion and not have any force to damage the vehicle
This is all you are going to get with a leak in the GSE
Unless anyone is operating off of additional information not shared with the rest of us, I think the evidence so far make an external detonation more likely, which is about as definite a statement as can be made from that evidence.
This is all you are going to get with a leak in the GSE
You get this assuming you have fire started in the immediate vincinity of any leak. However, if fire gets initiated later, you get this:
Nothing conclusive, but the detonation is bright and visible, seems to be located at or near the wall, and there's a very distinct lack of debris.Unless anyone is operating off of additional information not shared with the rest of us, I think the evidence so far make an external detonation more likely, which is about as definite a statement as can be made from that evidence.
Not at all. There is no public evidence that supports an external over internal explosion. And certainly, nothing from this thread or those first 3 frames.
Actually at that temperature I'd expect it to condense both N2 and O2 out of the air. :)Also super chilled lox (66k) condenses nitrogen out of air. Not that that would affect the anomaly.
More importantly, it condenses oxygen out of air (unless insulated), which has been observed on walls of uninsulated liquid hydrogen tanks. So there might be liquid oxygen in places where it should not be, without any leaks. Although I trust SpaceX took care to insulate everything.
Unless anyone is operating off of additional information not shared with the rest of us, I think the evidence so far make an external detonation more likely, which is about as definite a statement as can be made from that evidence. (meaning - not very definite...)
Most of that evidence is in the first 3 frames of video. Everything after that is cascading failure and highly speculative.
The source of the combustible material (and oxidizer) can be the rocket or the GSE, there hasn't been much evidence to support either case.
During a launch, there is often (always?) a camera looking right at the umbilical connections. I'd assume this camera is also activated for hot fires, and the recording from this camera seems like the first thing to check.
Can't address information I'm not privy to.Unless anyone is operating off of additional information not shared with the rest of us, I think the evidence so far make an external detonation more likely, which is about as definite a statement as can be made from that evidence. (meaning - not very definite...)
Most of that evidence is in the first 3 frames of video. Everything after that is cascading failure and highly speculative.
The source of the combustible material (and oxidizer) can be the rocket or the GSE, there hasn't been much evidence to support either case.
I (and I am sure others here also) labor under the burden of having good sources in the business who can't be revealed, and having certain knowledge that can't be shared, so yes, some of us are operating off of additional information – which may be right or wrong. Also, I don't share rumors to which I am privy, however well-sourced they may be. But I have, to my mind, fairly expressed certain COPV concerns in part due to "information received" and agree with Jim that an external event is likely to be insufficiently energetic to cause any appreciable damage to the vehicle.
The general similarity of this event to the in-flight failure should be causing eyebrows to be raised. The obvious retort is "how could the strut have failed again if the vehicle wasn't under acceleration? But an equally valid question is, what if the proximate cause of the in-flight failure wasn't the strut but the COPV itself failing?
Anyways, anything on the outside is just going to flash and not going to be an explosion and not have any force to damage the vehicle
>
FAE's can also be nasty, hence the media tag of the "Poor mans atomic bomb" but these require both careful mixing of fuel and air and controlled ignition delay. I think they also like fuels with high flame or explosion propagation speeds and I don't think RP1 is very good at this.
>
The general similarity of this event to the in-flight failure should be causing eyebrows to be raised. The obvious retort is "how could the strut have failed again if the vehicle wasn't under acceleration?" But an equally valid question is, "what if the proximate cause of the in-flight failure wasn't the strut but the COPV itself failing?"
(snip)
The general similarity of this event to the in-flight failure should be causing eyebrows to be raised. The obvious retort is "how could the strut have failed again if the vehicle wasn't under acceleration?" But an equally valid question is, "what if the proximate cause of the in-flight failure wasn't the strut but the COPV itself failing?"
Edit: punctuation
The general similarity of this event to the in-flight failure should be causing eyebrows to be raised. The obvious retort is "how could the strut have failed again if the vehicle wasn't under acceleration?" But an equally valid question is, "what if the proximate cause of the in-flight failure wasn't the strut but the COPV itself failing?"
I (and I am sure others here also) labor under the burden of having good sources in the business who can't be revealed, and having certain knowledge that can't be shared, so yes, some of us are operating off of additional information – which may be right or wrong. Also, I don't share rumors to which I am privy, however well-sourced they may be. But I have, to my mind, fairly expressed certain COPV concerns in part due to "information received" and agree with Jim that an external event is likely to be insufficiently energetic to cause any appreciable damage to the vehicle.
The general similarity of this event to the in-flight failure should be causing eyebrows to be raised. The obvious retort is "how could the strut have failed again if the vehicle wasn't under acceleration?" But an equally valid question is, "what if the proximate cause of the in-flight failure wasn't the strut but the COPV itself failing?"
Edit: punctuation
HMXHMX,
Perhaps there is something I am missing here, not being privy to the non-public details of the vehicle's internal design. I agree (not that my agreement matters), that COPV's are a great candidate for causing high energy events, like this anomaly. What makes me very curious, is what is so different about the design of the second stage that these vessels are an issue? We have seen these booster stages go through some pretty harsh treatment, and, at least from what we have seen publicly, no COPV failures have caused a LOV. So what's the difference? Tank wall thickness? Lighter, less rugged COPV's on the upper stage?
I know you might not be able to answer the question, but I thought it worth asking.
Edit: I am aware there have been anomalies in the first stage involving COPV's as well. I guess a follow-on question would be why did these not result in LOV? I am genuinely interested in learning about how these vehicles function.
I'm surprised to hear that there have been first stage COPV issues...I'm unaware of any, but would very much like links to any reports.
I'm surprised to hear that there have been first stage COPV issues...I'm unaware of any, but would very much like links to any reports.
The general similarity of this event to the in-flight failure should be causing eyebrows to be raised. The obvious retort is "how could the strut have failed again if the vehicle wasn't under acceleration?" But an equally valid question is, "what if the proximate cause of the in-flight failure wasn't the strut but the COPV itself failing?"
Granted your decades long history in this industry and your recent focus on COPV in this current thread.
Assuming a COPV failure, which would be in the LOX tank I presume, which would obviously rupture that tank, and possibly the RP1 tank at the same time, I'm confused as to how we'd end up with a detonation rather than a deflagration.
To me the debris tracks are indicative of detonation, while the rest of the event looks like deflagration.
Your thoughts please?
My take is an internal pressure related event (COPV is just one of possible causes) vs an event that is external to the vehicle.
And that is not based on any inside information. I have as much data as any man on the street, right now.
(snip)
The general similarity of this event to the in-flight failure should be causing eyebrows to be raised. The obvious retort is "how could the strut have failed again if the vehicle wasn't under acceleration?" But an equally valid question is, "what if the proximate cause of the in-flight failure wasn't the strut but the COPV itself failing?"
Edit: punctuation
If it indeed comes down to be a COPV blowing up then how come only the 2nd stage is FUBARed by this and not the 1st stage? From reading on this thread and others it's been made clear that the COPVs are the same on both stages. S1 would just need a lot more of them, actually, increasing the likelihood of a bad bad one getting in there. Is it the smaller volume of the S2 LOX tank that makes any COPV failure a LOV while a bottle popping inside the S1 tank has enough volume to spread out for safety valves to be able to cope with it or is the S1 just so much beefier due to reuse requirements that it can just handle the extra pressure from a COPV blowout? How would the Merlins behave if a He bottle went pop early in the launch phase, lets say 20-30sec into flight? I'm sure the He would get mixed a good bit with the LOX and get sucked into the engines and being not exactly a reactive element it should have some sort of an effect.
If that's indeed the case then the S2 COPVs need a design review. Smaller bottles in greater numbers to scale it to the same ratios as in the 1st stage as that has never gone boom due to this issue (think I read about a close call on this same thread for the first Orbcom mission).
If this is true, then why didn't the pressure vessel burst open as in CRS-7 accident, but there was some kind of explosion instead? IMHO, the plauseible expectation in case of any pressure vessel failure, is first to see large cloud of condensate and only then ignition. That was not the case.
Anything on the outside would show up before the vehicle exploded and there would be two distinct events
The general similarity of this event to the in-flight failure should be causing eyebrows to be raised. The obvious retort is "how could the strut have failed again if the vehicle wasn't under acceleration?" But an equally valid question is, "what if the proximate cause of the in-flight failure wasn't the strut but the COPV itself failing?"
Granted your decades long history in this industry and your recent focus on COPV in this current thread.
Assuming a COPV failure, which would be in the LOX tank I presume, which would obviously rupture that tank, and possibly the RP1 tank at the same time, I'm confused as to how we'd end up with a detonation rather than a deflagration.
To me the debris tracks are indicative of detonation, while the rest of the event looks like deflagration.
Your thoughts please?
If one of the two S2 COPVs fails catastrophically, that means the second COPV is also going to vent at a lower rate through what is left of its line. But about 90-100 kg of helium is going to be instantaneously released into the LOX tank from just the first failing bottle...that is pressurizing an ullage that is tiny (between 1-3% of tank volume is standard). Instantly the LOX tank is going to be at several hundred psia, failing the common bulkhead as well as the side walls. And the general shock wave from the failure is likely to be sufficient to cause some propellant mixing, though not much is required for the event to begin. It is also possible that COPV debris punctured the common bulkhead first, too.
I suggested a mechanism that might lead to in-tank combustion in a much early post but as the saying goes, "ignition is free." I don't have a specific source for ignition, just notions. Maybe torn wires sparking when the tank lets go?
I agree that this was a low-grade detonation, for all the word-smithing going on about deflagration. Actually, there are elements of both processes in the whole event. Separately, there are self-propelled objects like the COPV seen flying up and over the payload fairing. You can watch it vent helium as it tumbles along.
I've read whole thread, but I don't remember if any used this method...
The general similarity of this event to the in-flight failure should be causing eyebrows to be raised. The obvious retort is "how could the strut have failed again if the vehicle wasn't under acceleration?" But an equally valid question is, "what if the proximate cause of the in-flight failure wasn't the strut but the COPV itself failing?"
Granted your decades long history in this industry and your recent focus on COPV in this current thread.
Assuming a COPV failure, which would be in the LOX tank I presume, which would obviously rupture that tank, and possibly the RP1 tank at the same time, I'm confused as to how we'd end up with a detonation rather than a deflagration.
To me the debris tracks are indicative of detonation, while the rest of the event looks like deflagration.
Your thoughts please?
If one of the two S2 COPVs fails catastrophically, that means the second COPV is also going to vent at a lower rate through what is left of its line. But about 90-100 kg of helium is going to be instantaneously released into the LOX tank from just the first failing bottle...that is pressurizing an ullage that is tiny (between 1-3% of tank volume is standard). Instantly the LOX tank is going to be at several hundred psia, failing the common bulkhead as well as the side walls. And the general shock wave from the failure is likely to be sufficient to cause some propellant mixing, though not much is required for the event to begin. It is also possible that COPV debris punctured the common bulkhead first, too.
I suggested a mechanism that might lead to in-tank combustion in a much early post but as the saying goes, "ignition is free." I don't have a specific source for ignition, just notions. Maybe torn wires sparking when the tank lets go?
I agree that this was a low-grade detonation, for all the word-smithing going on about deflagration. Actually, there are elements of both processes in the whole event. Separately, there are self-propelled objects like the COPV seen flying up and over the payload fairing. You can watch it vent helium as it tumbles along.
Please don't mind me challenging you. :)
If you check my history in this particular thread, I've been chasing visible debris and trying to model their origins and velocity.
I know the difference between deflagration and detonation. I'm one of a few humans on the planet who saw an airburst from operation Dominick in 1962-3. I came from a long line of folks who play with things that go bang.
IMHO the item flying over the fairing is not a COPV, which is a long separate discussion, briefly, it's on a parabolic trajectory which I'm currently tracking user Tracker-4.94 which does such things. Drop that discussion for now.
The initial debris of concern is seen the the first and 2nd and possibly 3rd frame of the USLaunchReport video shooting to the right and up, and is decelerating but with an average velocity of about 1,000 feet per second. To me, that part can't seem to be moving that fast because of a deflagration. Earlier in the thread I provided images and interpretation of that debris. I'll replicate the images to save you time if you wish.
If a COPV fails, is the mixing and resulting combustion rate sufficient to propel debris at 1,000 feet per second, and if so, how? My hydrodynamics training suggests there is a mixing front that precedes a burning front and that relatively incompressible liquids will slow things down, not speed things up.
I am puzzled about how rupturing a LOX and RP1 tank results in an immediate ignition that propels some external object at 1,000 feet per second.
My question is, in your experience, is there a COPV failure scenario you are aware of that can result in a detonation that would propel an external object at that velocity?
I've read whole thread, but I don't remember if any used this method...
Method was first shown here... and again in some much later postings...
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1576505#msg1576505 (http://forum.nasaspaceflight.com/index.php?topic=30981.msg1576505#msg1576505)
My take is an internal pressure related event (COPV is just one of possible causes) vs an event that is external to the vehicle.
And that is not based on any inside information. I have as much data as any man on the street, right now.
If this is true, then why didn't the pressure vessel burst open as in CRS-7 accident, but there was some kind of explosion instead? IMHO, the plauseible expectation in case of any pressure vessel failure, is first to see large cloud of condensate and only then ignition. That was not the case.
Anything on the outside would show up before the vehicle exploded and there would be two distinct events
The general similarity of this event to the in-flight failure should be causing eyebrows to be raised. The obvious retort is "how could the strut have failed again if the vehicle wasn't under acceleration?" But an equally valid question is, "what if the proximate cause of the in-flight failure wasn't the strut but the COPV itself failing?"
Granted your decades long history in this industry and your recent focus on COPV in this current thread.
Assuming a COPV failure, which would be in the LOX tank I presume, which would obviously rupture that tank, and possibly the RP1 tank at the same time, I'm confused as to how we'd end up with a detonation rather than a deflagration.
To me the debris tracks are indicative of detonation, while the rest of the event looks like deflagration.
Your thoughts please?
If one of the two S2 COPVs fails catastrophically, that means the second COPV is also going to vent at a lower rate through what is left of its line. But about 90-100 kg of helium is going to be instantaneously released into the LOX tank from just the first failing bottle...that is pressurizing an ullage that is tiny (between 1-3% of tank volume is standard). Instantly the LOX tank is going to be at several hundred psia, failing the common bulkhead as well as the side walls. And the general shock wave from the failure is likely to be sufficient to cause some propellant mixing, though not much is required for the event to begin. It is also possible that COPV debris punctured the common bulkhead first, too.
I suggested a mechanism that might lead to in-tank combustion in a much early post but as the saying goes, "ignition is free." I don't have a specific source for ignition, just notions. Maybe torn wires sparking when the tank lets go?
I agree that this was a low-grade detonation, for all the word-smithing going on about deflagration. Actually, there are elements of both processes in the whole event. Separately, there are self-propelled objects like the COPV seen flying up and over the payload fairing. You can watch it vent helium as it tumbles along.
Please don't mind me challenging you. :)
If you check my history in this particular thread, I've been chasing visible debris and trying to model their origins and velocity.
I know the difference between deflagration and detonation. I'm one of a few humans on the planet who saw an airburst from operation Dominick in 1962-3. I came from a long line of folks who play with things that go bang.
IMHO the item flying over the fairing is not a COPV, which is a long separate discussion, briefly, it's on a parabolic trajectory which I'm currently tracking user Tracker-4.94 which does such things. Drop that discussion for now.
The initial debris of concern is seen the the first and 2nd and possibly 3rd frame of the USLaunchReport video shooting to the right and up, and is decelerating but with an average velocity of about 1,000 feet per second. To me, that part can't seem to be moving that fast because of a deflagration. Earlier in the thread I provided images and interpretation of that debris. I'll replicate the images to save you time if you wish.
If a COPV fails, is the mixing and resulting combustion rate sufficient to propel debris at 1,000 feet per second, and if so, how? My hydrodynamics training suggests there is a mixing front that precedes a burning front and that relatively incompressible liquids will slow things down, not speed things up.
I am puzzled about how rupturing a LOX and RP1 tank results in an immediate ignition that propels some external object at 1,000 feet per second.
My question is, in your experience, is there a COPV failure scenario you are aware of that can result in a detonation that would propel an external object at that velocity?
Anything on the outside would show up before the vehicle exploded and there would be two distinct events
There are two distinct event, or at least two visible phases of destruction... A detonation (3 video frames or so) and then the collapse of the entire rocket.
There may have been a "stage zero" inside the rocket, but if there was, it didn't show as any "cold" event that preceded the detonation.
A cloud of fuel vapor or aerosol would not necessarily have been visible. Depends on the weather. Also, if it sprayed from inside the rocket, it could have been very brief.
We don't have a video frame showing a detectable deformation in the rocket, or at least not a certain one.
--
Don't add meaning to what I say in the sense that I am not implying it's GSE. Very materialistically, I'm saying it looks like the first visible detonation was external.
It does not look like the tank burst outwards and then exploded, for example.
As was discussed extensively following the CRS-7 failure, composites don't "like" repeated cryogenic soak cycles, and there was some concern - before fault was pinned on a strut failure rather than the COPV itself - that perhaps SpaceX's practice of repeated tanking and tests prior to flight could have contributed.
To that point, although Elon pointed blame squarely at the failed strut, a GAO report regarding of NASA's handling of the CRS-7 failure investigation pointed out that the root cause was not 100% certain, with several other possible causes (I don't have a link handy and can't recall what other possible causes were implicated).
NASA’s Launch Services Program (LSP) conducted a separate, independent review of the failure, briefing
its results to senior NASA leadership on December 18, 2015. [24] LSP did not identify a single probable
cause for the launch failure, instead listing several “credible causes.” In addition to the material defects
in the strut assembly SpaceX found during its testing, LSP pointed to manufacturing damage or improper
installation of the assembly into the rocket as possible initiators of the failure. LSP also highlighted
improper material selection and such practices as individuals standing on flight hardware during the
assembly process, as possible contributing factors. [25]
[24] - LSP purchases commercial launch services for NASA customers, including missions of the Agency’s Science Mission Directorate. LSP had a contract with SpaceX to use the Falcon 9 to deliver a science mission payload.
[25] - In February 2016, the NASA Administrator and the Associate Administrator for the Human Exploration and Operations Mission Directorate sent a letter to SpaceX expressing concerns about the company’s systems engineering and management practices, hardware installation and repair methods, and telemetry systems based on LSP’s review of the failure.
I did step thought the video frame by frame, and what I believe I saw was a object with the approximate geometry and known dimensions of the helium COPV, self-propelled by venting helium though a tube that is somewhere between 1 and 1.5 inch diameter (tube dimension from photos of the vessels available on line). The object is being propelled by the venting gas, not the force of the detonation-deflagration. You can see the object nearly disappear in one frame when the tumble orients it base on to the camera and the cloud of venting gas obscures its shape.
If one went with the COPV failure theory as root cause for both failures, it would be interesting to work out what the chances would have been that both failures happened during launch campaigns and not in Texas.
There seems to be one object in this composite of two frames, the first & second frame of the USLaunchReport video. There are multiple assumptions that it's 60 frames per second, but it looks like the youtube version is 30 frames per second. Your milage may vary.... :)Youtube has multiple versions at different resolutions available - see the "Quality" menu which becomes available when you click on the gear on the lower right of the controls.
1080p60
720p60
480p
360p
240p
144p
The general similarity of this event to the in-flight failure should be causing eyebrows to be raised. The obvious retort is "how could the strut have failed again if the vehicle wasn't under acceleration?" But an equally valid question is, "what if the proximate cause of the in-flight failure wasn't the strut but the COPV itself failing?"
The general similarity of this event to the in-flight failure should be causing eyebrows to be raised. The obvious retort is "how could the strut have failed again if the vehicle wasn't under acceleration?" But an equally valid question is, "what if the proximate cause of the in-flight failure wasn't the strut but the COPV itself failing?"
This reply is a bit late, but I have a question specifically about your implication that the CRS-7 failure could have been caused by a failed COPV rather than a failed strut.
The COPV are under very high pressures to start with and if they fail, they will do so catastrophically (burst, unzip from the point of failure) and release the helium very rapidly. Is that a true statement?
The CRS-7 failure was very different from the AMOS-6 failure, because it occurred over a much longer period of time. The helium leak occurred over about 250ms, and the telemetry indicated partial loss and then recovery of pressure within the helium system. This flow rate exceeded the relief valve capacity, which is why the manhole cover blew off the top, which ultimately caused S2 collapse - but IMO a failed COPV would have actually ruptured S2 'instantly' from the pressure wave and looked very different.
So, I'd like clarification on how you think a failed COPV could have ended up causing CRS-7 failure given the long timelines involved.
I did step thought the video frame by frame, and what I believe I saw was a object with the approximate geometry and known dimensions of the helium COPV, self-propelled by venting helium though a tube that is somewhere between 1 and 1.5 inch diameter (tube dimension from photos of the vessels available on line). The object is being propelled by the venting gas, not the force of the detonation-deflagration. You can see the object nearly disappear in one frame when the tumble orients it base on to the camera and the cloud of venting gas obscures its shape.
LOL, thank you for not casting me into the pit of despair as others have done on this forum. :) For all who would love to down-vote me if this were Reddit, I have a 10 acre farm, 13 patents, and have a better solution in process for global internet services than Elon. We'll see who gets there first. :)
Below is the image reference that I'm trying to understand WRT to COPV failure.
There seems to be one object in this composite of two frames, the first & second frame of the USLaunchReport video. There are multiple assumptions that it's 60 frames per second, but it looks like the youtube version is 30 frames per second. Your milage may vary.... :)
The image depicts a hypothetical trajectory on a linear basis. That's the red line.
The black lines show the horizontal distance travel (X) but not Y or Z. The Right black line is the measurable line. The left line is the inferred line pointing to where that object may have originated. Frame 3 shows it on the same trajectory but 1/4 of the distance between frame suggesting that it is decelerating.
Assuming 30 fps, between Frame 1 and Frame 2, its average velocity is about 1,000 feet per second.
Now my problem is this. In Frame 0, there is no indication of any failure of any kind.
1/30th of a second later this object can be found, and 1/30th of a second later its X velocity implies it's moving at 1,000 feet per second, more or less.
When a COPV fails, in 1/30th of a second, it has to rupture the LOX and RP1 tanks, ignition has to occur, and the resulting detonation/deflagration has to propel this visible object to 1,000+ feet per second.
I'm really curious to know how a COPV failure can do that.
I can accept that a COPV failure can rupture tanks.
I have difficulty seeing how in 1/30th of a second, a COPV failure and ignition results in propelling even a ping pong ball. Gaining that kind of velocity from the resulting detontation/deflagration gets up to 1,000 feet per second if my photo interpretation is accurate.
I'm not saying a COPV failure didn't happen, I just don't know how that failure followed by tank failure, followed by ignition, gets my ping pong ball moving that fast.
You're clearly a COPV failure proponent, so I'm wondering if you can reconcile what I think I'm seeing, which is speculative, with what you know and have seen.
During a launch, there is often (always?) a camera looking right at the umbilical connections. I'd assume this camera is also activated for hot fires, and the recording from this camera seems like the first thing to check.
If this is true, then why didn't the pressure vessel burst open as in CRS-7 accident, but there was some kind of explosion instead? IMHO, the plauseible expectation in case of any pressure vessel failure, is first to see large cloud of condensate and only then ignition. That was not the case.
We cant externally see either of the domes which also comprise the pressure vessel. Maybe CRS-7 was what happens when the forward dome fails, and this is what happens when the aft dome fails.
You know what, I installed the frame-by-frame add-on and looked again.
It's more than I said before.
The first detonation event goes through about 5 key frames, expanding on the first 3, and then contracting.
As it does so, you can still see the "far" side of the stage, and it is undisturbed.
As the detonation event recedes, the there appears a lot of black smoke / liquid RP1, and the secondary melt-down ensues.
---
That was a description of what I saw. Interpretation? Still could equally be an external or internal failure.
--------
I recommend for all to install and watch for yourself. "[" and "]" for stepping through the frames. Get the 1080 video link from update thread.
I'll download the just released 2160p (4K) version and see if my opinion changes...
I'll download the just released 2160p (4K) version and see if my opinion changes...
FYI, that 4K isn't 4K. It's USLaunchReport trying to milk some more views on his video. It's an upscale that is actually lower quality with a bunch of extra pixelation (for the part where the explosion occurs) than the original 1080p. You shouldn't use the 4K for any analysis. He added a couple seconds of film of the pad burning that is actually 4K footage, but the rest of the video is not.
I'll download the just released 2160p (4K) version and see if my opinion changes...
FYI, that 4K isn't 4K. It's USLaunchReport trying to milk some more views on his video. It's an upscale that is actually lower quality with a bunch of extra pixelation (for the part where the explosion occurs) than the original 1080p. You shouldn't use the 4K for any analysis. He added a couple seconds of film of the pad burning that is actually 4K footage, but the rest of the video is not.
I'll download the just released 2160p (4K) version and see if my opinion changes...
FYI, that 4K isn't 4K. It's USLaunchReport trying to milk some more views on his video. It's an upscale that is actually lower quality with a bunch of extra pixelation (for the part where the explosion occurs) than the original 1080p. You shouldn't use the 4K for any analysis. He added a couple seconds of film of the pad burning that is actually 4K footage, but the rest of the video is not.
I checked and agree... I made changes in my 2nd post up above based on your finding... Thanks... :)
Hopefully this time they will be able to recover some debris, including the COPVs, and perform some forensics. They couldn't do this for CRS-7.This is what I am hoping as well. Last time the debris went in the drink and smashed into a million pieces this time even with the fire there should be some left.
The YouTube frame rate can be calculated from the number of frames needed to show the payload's fall. It is accelerating under gravity at 9.81 m/s/s or 32 feet/s/s.
v = u + at
Any other component gases or potentially a tank component for the first few nano seconds which would compromise the tank after which the rp 1 tank would probably be compromised leading to an abundance of fuel.
"The test articles will consist of vessels lined with Inconel 718 and Al-2219. Inconel 718 has been selected since it is LO2 compatible and it provides excellent corrosion resistance and provides good material fracture toughness at cryogenic temperatures.2 Al-2219 has been selected since it is lighter in weight and it can be used if the risk of exposure to LOX is acceptable based on the propulsion system design ... The 31-43B resin has been selected based on previous research and development work performed by ARDE’, Inc. The Toray T-1000 carbon fiber by Torayca has been selected since NASA plans to use it for the fabrication of the flight vessels."
...
Following are the test procedures to be performed on the series of test articles.
Ambient
1. Perform 2 proof pressure tests hydrostatically to 1.25 X MOP = 5625 psig.
2. Perform 100 pressure cycles from 0 to 4,500 psig with water.
3. Perform hydrostatic burst pressure tests using Digital Imaging Correlation (DIC) equipment to measure the strain as the pressure is increased to the rupture event.
Cryogenic
1. Perform 2 proof pressure tests to 1.25 X MOP = 5625 psig at -320°F where LN2 is in the COPV and GN2 is the pressurant.
2. Perform thermal cycle testing 5 times where the COPV is filled with and submerged in LN2 with no applied pressure.
3. Perform 100 pressure cycles charging to 4,500 psig at -320°F using LN2 where GN2 is the pressurant while the COPV is submerged in LN2.
4. Perform burst pressure tests with LN2 at -320°F.
...
These results for the burst tests for both Inconel 718 and Al-2219 show that the minimum burst pressure was met where the smallest burst pressure is 2.36 X MOP or 10,620 psig for the cryogenic burst tests of Inconel 718. Comparisons of the Al-2219 versus the Inconel 718 show that the Al-2219 provided higher burst pressures at a lower vessel weight than the Inconel 718. The Al-2219 vessels have more overwrap due to the reduced tensile strength of Al-2219 but the results show that Al-2219 can provide the required burst pressures after proof tests, pressure cycles and thermal cycles.
...
The remaining risk for COPVs that needs to be tested regards stress rupture life at cryogenic conditions.
We are more or less in agreement but I don't think an internal ignition of some kind can yet be ruled out.Any other component gases or potentially a tank component for the first few nano seconds which would compromise the tank after which the rp 1 tank would probably be compromised leading to an abundance of fuel.
Having combustible gas component in the oxygen tank ullage would denote a colossal GSE flaw. Incomplete purging of atmosphere would not suffice here. Would have to contaminate the tank with some light alkane or hydrogen.
Some other contamination, a big blob of grease etc? Maybe, but again a colossal procedural flaw.
A tank component burning? One would think people have learned from Apollo 13 but the COPVs themselves might sustain a fire if ignited. Even Teflon burns in pure oxygen so I guess composite resins too. Exposed carbon fiber most certainly would. Dunno if the COPVs are protected with some passive layer.
Anyhow, on a general note I think the COPV is one way or the other the most probable culprit. There seems to be nothing out of the ordinary in one frame and bigbadaboom well on its way in the next frame. Hard to imagine anything other than COPV or FTS exploding doing that. Shape of the explosion and long proven track record all but rule out FTS.
The COPVs appear to be in the upper part of the LOX tank, adjacent to tank walls. If one goes pop it is more like to immediately burst through the minimum resistance path, tank wall, than have time to rupture common bulkhead, mix RP-1 and oxygen at correct ratio, and then either ignite it inside the tank or spray a cloud of explosive mixture outside the vehicle and ignite that.
Btw the one in the imagery supposedly flying out venting helium might not be the one which originally failed, but one next to it deciding to exit the scene.
Before I go any further, I currently hold no opinion on the LOV incident, other than it was energetic and extremely fast. 3 frames of video shot from 4km away does not provide enough data to draw a conclusion. Having said that, there seems to be a lot of discussion regarding COPV cyro compatibility being insurmountable - two pages ago I posted a link to a NASA article on COPV cyro testing which is worth a read:Quote"The test articles will consist of vessels lined with Inconel 718 and Al-2219. Inconel 718 has been selected since it is LO2 compatible and it provides excellent corrosion resistance and provides good material fracture toughness at cryogenic temperatures.2 Al-2219 has been selected since it is lighter in weight and it can be used if the risk of exposure to LOX is acceptable based on the propulsion system design ... The 31-43B resin has been selected based on previous research and development work performed by ARDE’, Inc. The Toray T-1000 carbon fiber by Torayca has been selected since NASA plans to use it for the fabrication of the flight vessels."
...
Following are the test procedures to be performed on the series of test articles.
Ambient
1. Perform 2 proof pressure tests hydrostatically to 1.25 X MOP = 5625 psig.
2. Perform 100 pressure cycles from 0 to 4,500 psig with water.
3. Perform hydrostatic burst pressure tests using Digital Imaging Correlation (DIC) equipment to measure the strain as the pressure is increased to the rupture event.
Cryogenic
1. Perform 2 proof pressure tests to 1.25 X MOP = 5625 psig at -320°F where LN2 is in the COPV and GN2 is the pressurant.
2. Perform thermal cycle testing 5 times where the COPV is filled with and submerged in LN2 with no applied pressure.
3. Perform 100 pressure cycles charging to 4,500 psig at -320°F using LN2 where GN2 is the pressurant while the COPV is submerged in LN2.
4. Perform burst pressure tests with LN2 at -320°F.
...
These results for the burst tests for both Inconel 718 and Al-2219 show that the minimum burst pressure was met where the smallest burst pressure is 2.36 X MOP or 10,620 psig for the cryogenic burst tests of Inconel 718. Comparisons of the Al-2219 versus the Inconel 718 show that the Al-2219 provided higher burst pressures at a lower vessel weight than the Inconel 718. The Al-2219 vessels have more overwrap due to the reduced tensile strength of Al-2219 but the results show that Al-2219 can provide the required burst pressures after proof tests, pressure cycles and thermal cycles.
...
The remaining risk for COPVs that needs to be tested regards stress rupture life at cryogenic conditions.
100 cycles whilst charged to 4500psi with (and immersed in) LN2 seems like a good data point to me regarding performance of tailored composites in cryogenic conditions. I would be more interested in the LOX compatibility of the Al liner material, which the article somewhat sidesteps.
Cheers,
Andy
Spyx helium system is known to run in excess of 6000 psi. Fyi
Does anyone know when in the count Stage 2 helium loading occurs?
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1577625#msg1577625
Does anyone know when in the count Stage 2 helium loading occurs?
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1577625#msg1577625
Bad form to quote myself but I haven't been able to find this info and the question may have been lost in the crush yesterday by someone who does know.
COPV or not COPV, that is the question.... unless they are a pressurised COPV. That would bounce very good.
Let me pose some puzzlers for the folks that are now in the pro-COPV camp.
1. Image 1 below, showing the object moving up to the right, compared to Image 2 below, showing the trajectory path through the F9. Is there a COPV on any part of that trajectory path? If not, how did it get on the observed trajectory? Keep in mind, most things moving at 1,000 feet per second don't bounce very well on impact.
2. Original first frame of the event, Image 3 below under different leveling modes. How does a COPV failure also create a detonation front that consumes 35 X 85 feet of burn front in one frame? That detonation front is clearly not mostly reflection and lens aberrations.
3. Original discussion thingee now dubbed an obvious COPV. How does it blow out the side of the tank to the right, then end up shooting vertical centered on the tower, and loop to the left? Image 4 (produced by eeergo). Also, if you measure it's size in early frames, you see that it's asymmetric and much larger than a COPV would be, unless it's headed towards the camera at an amazing speed or has become a pancake. Image 5
Does anyone know when in the count Stage 2 helium loading occurs?
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1577625#msg1577625
Bad form to quote myself but I haven't been able to find this info and the question may have been lost in the crush yesterday by someone who does know.
Spaceflight 101 has it at
T-0:13:15 Stage 2 Helium Loading
http://spaceflight101.com/falcon-9-ft-countdown-timeline/
Has anybody tried liquid helium storage in dewar flask as a helium source? Eliminates the high pressure.
What is the difference in the helium design of the second stage vs the first stage? They have never had a problem with the first stage. If they use basically the same kerolox engines. Only difference is the upper engine is designed for vacuum.
COPV or not COPV, that is the question.... unless they are a pressurised COPV. That would bounce very good.
Let me pose some puzzlers for the folks that are now in the pro-COPV camp.
1. Image 1 below, showing the object moving up to the right, compared to Image 2 below, showing the trajectory path through the F9. Is there a COPV on any part of that trajectory path? If not, how did it get on the observed trajectory? Keep in mind, most things moving at 1,000 feet per second don't bounce very well on impact.Quote
2. Original first frame of the event, Image 3 below under different leveling modes. How does a COPV failure also create a detonation front that consumes 35 X 85 feet of burn front in one frame? That detonation front is clearly not mostly reflection and lens aberrations.
3. Original discussion thingee now dubbed an obvious COPV. How does it blow out the side of the tank to the right, then end up shooting vertical centered on the tower, and loop to the left? Image 4 (produced by eeergo). Also, if you measure it's size in early frames, you see that it's asymmetric and much larger than a COPV would be, unless it's headed towards the camera at an amazing speed or has become a pancake. Image 5
There are at least 4 COPVs in S2, iirc. If one of them failed, mangled the inside of the S2 and caused the propellants to mix and ignite, the other three would be torn loose and propelled by the pressurised helium inside them to basically any trajectory.
COPV or not COPV, that is the question.... unless they are a pressurised COPV. That would bounce very good.
Let me pose some puzzlers for the folks that are now in the pro-COPV camp.
1. Image 1 below, showing the object moving up to the right, compared to Image 2 below, showing the trajectory path through the F9. Is there a COPV on any part of that trajectory path? If not, how did it get on the observed trajectory? Keep in mind, most things moving at 1,000 feet per second don't bounce very well on impact.Quote
2. Original first frame of the event, Image 3 below under different leveling modes. How does a COPV failure also create a detonation front that consumes 35 X 85 feet of burn front in one frame? That detonation front is clearly not mostly reflection and lens aberrations.
3. Original discussion thingee now dubbed an obvious COPV. How does it blow out the side of the tank to the right, then end up shooting vertical centered on the tower, and loop to the left? Image 4 (produced by eeergo). Also, if you measure it's size in early frames, you see that it's asymmetric and much larger than a COPV would be, unless it's headed towards the camera at an amazing speed or has become a pancake. Image 5
There are at least 4 COPVs in S2, iirc. If one of them failed, mangled the inside of the S2 and caused the propellants to mix and ignite, the other three would be torn loose and propelled by the pressurised helium inside them to basically any trajectory.
OK, let's see some COPV hand waving on this one.
The first image below is a fragment shooting up and to the left, visible in three frames, with a line through it's trajectory path. This one obviously could not have bounced off the tower. (720p version on YouTube).
On that trajectory, how does a COPV or any other fragment get on this trajectory? Is this also a COPV moving at 700+ feet per second? If it's not a COPV, why is the other one a COPV but this one isn't.
And what's at the intersection of the two mapped trajectories?
Just a little physics. Assume a COPV weighs a paltry 20 kg and is moving at 300 meters per second. It's got 900,000 joules of kinetic energy when it impacts a steal beam and bounces. Exactly how does that become an elastic collision instead of a shattering event?
Are you an expert on COPV construction, fracture mechanics and collision physics? How exactly did a 2 pound piece of foam result in the destruction of a an entire shuttle orbiter and loss of 7 crew members?
Are you an expert on COPV construction, fracture mechanics and collision physics? How exactly did a 2 pound piece of foam result in the destruction of a an entire shuttle orbiter and loss of 7 crew members?
Nope ...
Is that green line the object I mentioned two pages back post#1164?
Are you an expert on COPV construction, fracture mechanics and collision physics? How exactly did a 2 pound piece of foam result in the destruction of a an entire shuttle orbiter and loss of 7 crew members?
Nope, are you? Most of the knowledge here on COPVs comes from technical articles, testing reports from NASA and ESA, and some studies of truck collisions in the EU. If someone has ever worked on manufacturing or destructive testing of COPVs it would be wonderful if they'd chime in.
Another fragment trajectory shown below, followed by the paths' intersections. Clearly not converging to a single point.
Are you an expert on COPV construction, fracture mechanics and collision physics? How exactly did a 2 pound piece of foam result in the destruction of a an entire shuttle orbiter and loss of 7 crew members?
Nope ...
Then really, should you be tossing out the barrage of conclusory remarks about what a COPV will or won't do in a decidedly off-nominal event in close proximity to a low-order detonation/high-energy deflagration like this?
Is that green line the object I mentioned two pages back post#1164?
COPV or not COPV, that is the question.... unless they are a pressurised COPV. That would bounce very good.
Let me pose some puzzlers for the folks that are now in the pro-COPV camp.
1. Image 1 below, showing the object moving up to the right, compared to Image 2 below, showing the trajectory path through the F9. Is there a COPV on any part of that trajectory path? If not, how did it get on the observed trajectory? Keep in mind, most things moving at 1,000 feet per second don't bounce very well on impact.Quote
2. Original first frame of the event, Image 3 below under different leveling modes. How does a COPV failure also create a detonation front that consumes 35 X 85 feet of burn front in one frame? That detonation front is clearly not mostly reflection and lens aberrations.
3. Original discussion thingee now dubbed an obvious COPV. How does it blow out the side of the tank to the right, then end up shooting vertical centered on the tower, and loop to the left? Image 4 (produced by eeergo). Also, if you measure it's size in early frames, you see that it's asymmetric and much larger than a COPV would be, unless it's headed towards the camera at an amazing speed or has become a pancake. Image 5
There are at least 4 COPVs in S2, iirc. If one of them failed, mangled the inside of the S2 and caused the propellants to mix and ignite, the other three would be torn loose and propelled by the pressurised helium inside them to basically any trajectory.
OK, let's see some COPV hand waving on this one.
The first image below is a fragment shooting up and to the left, visible in three frames, with a line through it's trajectory path. This one obviously could not have bounced off the tower. (720p version on YouTube).
On that trajectory, how does a COPV or any other fragment get on this trajectory? Is this also a COPV moving at 700+ feet per second? If it's not a COPV, why is the other one a COPV but this one isn't.
And what's at the intersection of the two mapped trajectories?
Just a little physics. Assume a COPV weighs a paltry 20 kg and is moving at 300 meters per second. It's got 900,000 joules of kinetic energy when it impacts a steal beam and bounces. Exactly how does that become an elastic collision instead of a shattering event?
Thanks, not yet... I'm getting a bit "cross-eyed" looking for them with the bird distractions. ;D I'll get back to you all if I do. A suggestion would be to add some vector arrowheads to yours lines clarity... ;)
Is that green line the object I mentioned two pages back post#1164?
Yes it is, find any others? :)
Here is a liquid helium pressurization tank.
http://www.airliquideadvancedtechnologies.com/en/our-offer/space/programs/supercritical-helium-pressurization-tank-for-ariane-5.html
So this was asked upthread a ways.
What do other vehicles use for helium bottles?
I noticed the atlas V uses helium bottles but I can't seem to find any info on their construction. They appear to be not inside of the tanks. Spaceflight101 just lists helium bottles. This diagram just shows their location for the rd180 and the rl10. The rl10 definitely isn't inside of a tank. Not sure about the lox tank for the rd180. Looks to be at the bottom of the lox tank.
http://www.ulalaunch.com/uploads/docs/Atlas500_Cutaway.pdf
interesting that no one has taken perspective into account when doing debris trajectories. Because the camera shows something moving down and to the left they seem to assume it is infact moving down and to the left where infact it could be heading towards the camera, with only one angle trajectory plots are just wild guesses. Also lens flares/starbusts do not always point to the brightest area on a flat image as the convex lens will bend light . if you notice lens flares (and u can even try this with your own camera) will occur at an angle to the lens never head on. starbursts are more accurate but even they can be affected by the lens and pan and tilt anglesI mentioned perspective several pages back...
Here is a liquid helium pressurization tank.
http://www.airliquideadvancedtechnologies.com/en/our-offer/space/programs/supercritical-helium-pressurization-tank-for-ariane-5.html
Super critical is not the same as liquid
Any reports on the condition of the launch pad?
It isn't clear which system ariane V uses currently.
Here is a copv version.
http://www.sciencephoto.com/media/87925/view
3. Original discussion thingee now dubbed an obvious COPV. How does it blow out the side of the tank to the right, then end up shooting vertical centered on the tower, and loop to the left? Image 4 (produced by eeergo). Also, if you measure it's size in early frames, you see that it's asymmetric and much larger than a COPV would be, unless it's headed towards the camera at an amazing speed or has become a pancake.
It isn't clear which system ariane V uses currently.
Here is a copv version.
http://www.sciencephoto.com/media/87925/view
Looks like external COPV's: http://www.zamandayolculuk.com/pu-3/roket_ar5_corestage.jpg
On the two items seen in first 5 frames... one going left... one going right...
And including the 3rd item that I and others noted in about frames 6 thru 10 or so...
You seem to be thinking in 2D... based on my interpretation of the talking points your making...
The LONG zoom lens on the camera is messing with us... that I am sure of... ;)
My opinion... there is a lot of movement towards or away from the camera on all three flying small items...
And the only thing I'm kinda sure about... is the 3rd items is going away fast... :-\
The left and right items... I am not sure how much Z speed they have... and in which direction.
In any case... the Z speed will drastically alter the intersection point... assuming these came from about the same place...
As to the likely COPV chunk seen long after the situation unfolds...
It's about as interesting as the COPV much later chucked from S1 and impacting the right lightning tower... to me...
It's interesting that it first appeared at about 1/3 second after it all started...
But at 1/3 of a second... there wasn't much left structurally of S2... in my opinion...
To me, this may not point to a root cause, but for the initial event which seems to me to have been a detonation rather than a deflagration, tracing multiple objects helps constrain the physical volume of that event. The counter argument seems to be that a bunch of COPVs lose their He and become little rockets that shoot out ahead of the deflagration which would make the tracing exercise meaningless.
For me, for now, I'm assuming an external detonation is the first energy release in the event, and the trajectory tracing helps constrain the scope of that event. Others heartily disagree.
3. Original discussion thingee now dubbed an obvious COPV. How does it blow out the side of the tank to the right, then end up shooting vertical centered on the tower, and loop to the left? Image 4 (produced by eeergo). Also, if you measure it's size in early frames, you see that it's asymmetric and much larger than a COPV would be, unless it's headed towards the camera at an amazing speed or has become a pancake.
The trajectory has been concerning me as far as labelling it a COPV is concerned.
Your composite image shows it originating from a point to the right of the vehicle - for it to have been part of the vehicle, it would have had to deflect off the erector to change the trajectory, otherwise it would have headed towards the right of the frame.
I'm with your later comment that it's highly unlikely to be a COPV deflecting off the erector. Regardless of the elasticity of various components, there are two problems with that being the COPV:
(1) The odds of it hitting a part of the erector that deflected it would be very slight - firstly, it would have had to hit an outer upright exactly evenly, otherwise it would have ended up embedded within the lattice of the structure. Secondly, had it not bounced off an upright and gone into the frame of the erector, it wouldn't come out. Thirdly, it would have had to pass through the clamping structure that holds the top of the vehicle - and that remained intact enough to hold the payload fairing for several seconds after.
(2) If you count the frames from the initial explosion to the point the object becomes visible flying out of the fireball, it's 20 (+/-1). Count forwards 20 frame from there and take a fix on the position and it's a couple of metres above the top of the fairing. That gives you an approximate distance travelled in the 20 frames after it becomes visible, so assuming a relatively constant velocity, the same distance back from the frame it was first visible should give you the approximate start point. (See attached image).
On that basis, it's unlikely this is a COPV (or anything else that was part of the vehicle). My guess would be this is part of the erector, liberated by the shockwave of the blast.
3. Original discussion thingee now dubbed an obvious COPV. How does it blow out the side of the tank to the right, then end up shooting vertical centered on the tower, and loop to the left? Image 4 (produced by eeergo). Also, if you measure it's size in early frames, you see that it's asymmetric and much larger than a COPV would be, unless it's headed towards the camera at an amazing speed or has become a pancake.
The trajectory has been concerning me as far as labelling it a COPV is concerned.
Your composite image shows it originating from a point to the right of the vehicle - for it to have been part of the vehicle, it would have had to deflect off the erector to change the trajectory, otherwise it would have headed towards the right of the frame.
I'm with your later comment that it's highly unlikely to be a COPV deflecting off the erector. Regardless of the elasticity of various components, there are two problems with that being the COPV:
(1) The odds of it hitting a part of the erector that deflected it would be very slight - firstly, it would have had to hit an outer upright exactly evenly, otherwise it would have ended up embedded within the lattice of the structure. Secondly, had it not bounced off an upright and gone into the frame of the erector, it wouldn't come out. Thirdly, it would have had to pass through the clamping structure that holds the top of the vehicle - and that remained intact enough to hold the payload fairing for several seconds after.
(2) If you count the frames from the initial explosion to the point the object becomes visible flying out of the fireball, it's 20 (+/-1). Count forwards 20 frame from there and take a fix on the position and it's a couple of metres above the top of the fairing. That gives you an approximate distance travelled in the 20 frames after it becomes visible, so assuming a relatively constant velocity, the same distance back from the frame it was first visible should give you the approximate start point. (See attached image).
On that basis, it's unlikely this is a COPV (or anything else that was part of the vehicle). My guess would be this is part of the erector, liberated by the shockwave of the blast.
3. Original discussion thingee now dubbed an obvious COPV. How does it blow out the side of the tank to the right, then end up shooting vertical centered on the tower, and loop to the left? Image 4 (produced by eeergo). Also, if you measure it's size in early frames, you see that it's asymmetric and much larger than a COPV would be, unless it's headed towards the camera at an amazing speed or has become a pancake.
The trajectory has been concerning me as far as labelling it a COPV is concerned.
Your composite image shows it originating from a point to the right of the vehicle - for it to have been part of the vehicle, it would have had to deflect off the erector to change the trajectory, otherwise it would have headed towards the right of the frame.
I'm with your later comment that it's highly unlikely to be a COPV deflecting off the erector. Regardless of the elasticity of various components, there are two problems with that being the COPV:
(1) The odds of it hitting a part of the erector that deflected it would be very slight - firstly, it would have had to hit an outer upright exactly evenly, otherwise it would have ended up embedded within the lattice of the structure. Secondly, had it not bounced off an upright and gone into the frame of the erector, it wouldn't come out. Thirdly, it would have had to pass through the clamping structure that holds the top of the vehicle - and that remained intact enough to hold the payload fairing for several seconds after.
(2) If you count the frames from the initial explosion to the point the object becomes visible flying out of the fireball, it's 20 (+/-1). Count forwards 20 frame from there and take a fix on the position and it's a couple of metres above the top of the fairing. That gives you an approximate distance travelled in the 20 frames after it becomes visible, so assuming a relatively constant velocity, the same distance back from the frame it was first visible should give you the approximate start point. (See attached image).
On that basis, it's unlikely this is a COPV (or anything else that was part of the vehicle). My guess would be this is part of the erector, liberated by the shockwave of the blast.
This image shows the emergence of the object frame by frame. Also, using a 17' fairing size as reference, the object appears to have a longest dimension of about 5 feet. If you look at the images to the left of where its appearance is obvious, it is obscuring parts of the tower several frames prior to your 20 frame point.
Two questions:
1. What equipment is on the T/E near S2? Obvious items include the cradle arms, the hydraulic pistons that open the cradle, the RP-1 and LOX umbilicals, and the payload umbilical. Is there any active equipment up there like a pump, heat exchanger, etc?
2. What's the combined thickness of the S2 outer skin + the wall of the LOX tank?
Just to clue you in on where I'm going with this, I'm pondering whether a piece of shrapnel from failing equipment on the T/E might have impacted the stage and/or the LOX umbilical.
Spyx helium system is known to run in excess of 6000 psi. Fyi
4500psi was the design MOP for the test articles - that in itself does not preclude designing tanks for a higher MOP. FYI.
Additionally, as previously quoted the lowest burst pressure was "2.36 X MOP or 10,620 psig".
The COPV is about 22 inches in diameter and about 60 inches long. Just for reference.
So this was asked upthread a ways.
What do other vehicles use for helium bottles?
I noticed the atlas V uses helium bottles but I can't seem to find any info on their construction. They appear to be not inside of the tanks. Spaceflight101 just lists helium bottles. This diagram just shows their location for the rd180 and the rl10. The rl10 definitely isn't inside of a tank. Not sure about the lox tank for the rd180. Looks to be at the bottom of the lox tank.
http://www.ulalaunch.com/uploads/docs/Atlas500_Cutaway.pdf
Two questions:
1. What equipment is on the T/E near S2? Obvious items include the cradle arms, the hydraulic pistons that open the cradle, the RP-1 and LOX umbilicals, and the payload umbilical. Is there any active equipment up there like a pump, heat exchanger, etc?
2. What's the combined thickness of the S2 outer skin + the wall of the LOX tank?
Just to clue you in on where I'm going with this, I'm pondering whether a piece of shrapnel from failing equipment on the T/E might have impacted the stage and/or the LOX umbilical.
As to your question #1...
I've been looking at this picture zoomed in close for 2 days now asking the same question...
Source...
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1577399#msg1577399 (http://forum.nasaspaceflight.com/index.php?topic=30981.msg1577399#msg1577399)
On edit...
It's from the other side... and from an earlier mission obviously...
But it still seems useful on close inspection... zoomed in...
Now that's a silly question Jim. You darn well know that Helium dewar flasks have flown on a number of launches, just not as part of the rocket ;-)Has anybody tried liquid helium storage in dewar flask as a helium source? Eliminates the high pressure.
The gas is need for its pressure. Liquid does no good. How much does a dewar flask cost and weigh? And have any flown before?
The flash started higher up on the stage. Near the middle of it
3. Original discussion thingee now dubbed an obvious COPV. How does it blow out the side of the tank to the right, then end up shooting vertical centered on the tower, and loop to the left? Image 4 (produced by eeergo). Also, if you measure it's size in early frames, you see that it's asymmetric and much larger than a COPV would be, unless it's headed towards the camera at an amazing speed or has become a pancake.
The trajectory has been concerning me as far as labelling it a COPV is concerned.
Your composite image shows it originating from a point to the right of the vehicle - for it to have been part of the vehicle, it would have had to deflect off the erector to change the trajectory, otherwise it would have headed towards the right of the frame.
I'm with your later comment that it's highly unlikely to be a COPV deflecting off the erector. Regardless of the elasticity of various components, there are two problems with that being the COPV:
(1) The odds of it hitting a part of the erector that deflected it would be very slight - firstly, it would have had to hit an outer upright exactly evenly, otherwise it would have ended up embedded within the lattice of the structure. Secondly, had it not bounced off an upright and gone into the frame of the erector, it wouldn't come out. Thirdly, it would have had to pass through the clamping structure that holds the top of the vehicle - and that remained intact enough to hold the payload fairing for several seconds after.
(2) If you count the frames from the initial explosion to the point the object becomes visible flying out of the fireball, it's 20 (+/-1). Count forwards 20 frame from there and take a fix on the position and it's a couple of metres above the top of the fairing. That gives you an approximate distance travelled in the 20 frames after it becomes visible, so assuming a relatively constant velocity, the same distance back from the frame it was first visible should give you the approximate start point. (See attached image).
On that basis, it's unlikely this is a COPV (or anything else that was part of the vehicle). My guess would be this is part of the erector, liberated by the shockwave of the blast.
This image shows the emergence of the object frame by frame. Also, using a 17' fairing size as reference, the object appears to have a longest dimension of about 5 feet. If you look at the images to the left of where its appearance is obvious, it is obscuring parts of the tower several frames prior to your 20 frame point.
The COPV is about 22 inches in diameter and about 60 inches long. Just for reference.
It seems unlikely to me that enough aerosol would collect upwind of the rocket, well above the umbilical cords, without some sort of obvious pressurized spray. But I don't know how to estimate the size of the initial explosion nor how much RP-1/O2 aerosol it would take to generate it.>
FAE's can also be nasty, hence the media tag of the "Poor mans atomic bomb" but these require both careful mixing of fuel and air and controlled ignition delay. I think they also like fuels with high flame or explosion propagation speeds and I don't think RP1 is very good at this.
>
Haven't spent much time around grain elevators or bins? No careful mixing there at all. Vapors will also blow without careful mixing, been there with poorly stored fuels.
Things you learn growing up on a farm.
An improvised explosive can be made using a tin of flour and a small dispersion charge. Old tech my uncle used as a vintage SO. The damnedest things can be bombs.
The flash started higher up on the stage. Near the middle of it
Pretty much at the intertank / the s-bend on the pipe running up the erector at the point where it appears to have been stretched to transition from F9 1.1 to FT.
Either of these could be part of the cause of the anomaly, or neither of them.
I'm tending towards the ignition location of the explosion not necessarily being the same as the root cause.
There is no separate payload umbilical line. It is part of the second stage lines. The only thing going into the fairing is the AC duct.
It seems unlikely to me that enough aerosol would collect upwind of the rocket, well above the umbilical cords, without some sort of obvious pressurized spray. But I don't know how to estimate the size of the initial explosion nor how much RP-1/O2 aerosol it would take to generate it.>
FAE's can also be nasty, hence the media tag of the "Poor mans atomic bomb" but these require both careful mixing of fuel and air and controlled ignition delay. I think they also like fuels with high flame or explosion propagation speeds and I don't think RP1 is very good at this.
>
Haven't spent much time around grain elevators or bins? No careful mixing there at all. Vapors will also blow without careful mixing, been there with poorly stored fuels.
Things you learn growing up on a farm.
An improvised explosive can be made using a tin of flour and a small dispersion charge. Old tech my uncle used as a vintage SO. The damnedest things can be bombs.
Issues with this scenario:
1. There's a wind out there, so FAE is difficult, but not impossible to form
2. Such a cloud of dispersed fuel should have been seen (although the actual fireball may have been a lot smaller when measured from images due to lit surroundings.
3. WTF formed the FAE mixture in first place.
Issues with this scenario:
1. There's a wind out there, so FAE is difficult, but not impossible to form
2. Such a cloud of dispersed fuel should have been seen (although the actual fireball may have been a lot smaller when measured from images due to lit surroundings.
3. WTF formed the FAE mixture in first place.
*IF* the pipe running through the s-bend in the extendable section of the erector carries LOX (and not aircon), then gaseous release from that would be blown towards the vehicle, which would be consistent with the location of the explosion.
...
Call it either way - I don't think we can get an answer without other camera angles (and probably access to SpaceX's telemetry data).
Especially when we're working off a few frames of 60 fps (16.67 ms resolution) video from a couple miles away. There is no smoking gun in the video.Issues with this scenario:
1. There's a wind out there, so FAE is difficult, but not impossible to form
2. Such a cloud of dispersed fuel should have been seen (although the actual fireball may have been a lot smaller when measured from images due to lit surroundings.
3. WTF formed the FAE mixture in first place.
*IF* the pipe running through the s-bend in the extendable section of the erector carries LOX (and not aircon), then gaseous release from that would be blown towards the vehicle, which would be consistent with the location of the explosion.
...
Call it either way - I don't think we can get an answer without other camera angles (and probably access to SpaceX's telemetry data).
First of all - additional oxygen is NOT needed for FAE. The problem with the FAE scenario is that normally this environment there is fule-deprived.
But I agree with you, that our chances to determine whether any of our scenarios have something to do with reality are effectively nil
First of all - additional oxygen is NOT needed for FAE. The problem with the FAE scenario is that normally this environment there is fuel-deprived.
But I agree with you, that our chances to determine whether any of our scenarios have something to do with reality are effectively nil
This was noted earlier, but might need a reminder - SpaceCom was about to be sold to a Chinese buyer, contingent on successful Amos-6 launch. The deal is currently not happening, afaik."Spacecom to recoup $173m, plus interest, for destroyed satellite"
http://www.timesofisrael.com/spacecom-to-recoup-173m-plus-interest-for-destroyed-satellite/ (http://www.timesofisrael.com/spacecom-to-recoup-173m-plus-interest-for-destroyed-satellite/)
$205M +$50M (or a free launch) + $39M
Now, if they can stay in business...QuoteThe satellite’s owners, Space Communication, will receive over $173 million from IAI plus interest, which provided insurance for the device, a company official said.
According to Space Communication, also known as SpaceCom, the total sum from IAI is “approximately $205 million.”
Under the insurance policy, IAI will have to pay the amount “in under 60 days,” a spokesperson for the quasi-governmental firm said.
In addition, the Israeli company said it expects to receive either $50 million from SpaceX or “have the launch of a future satellite carried out under the existing agreement and with the payments that have [already] been made.”
Additional insurers are expected to pay SpaceCom an additional $39 million, the company said in a statement Saturday night.
It isn't clear which system ariane V uses currently.
Here is a copv version.
http://www.sciencephoto.com/media/87925/view
It isn't clear which system ariane V uses currently.
Here is a copv version.
http://www.sciencephoto.com/media/87925/view
A question I have as well for the industry folks. Does any other rocket put COPVs in the LOX tanks? If so, which one(s)?
The flash ignition is clearly to one side, but the collapse is symmetric and is unaccompanied by a noticeable, one-sided concussive force (the camera *is* very far away, granted). If the failure was initiated externally, it's more likely to be via an externally applied over-pressurization, or something went ballistic through the tank walls. I don't think an accelerated insulation fire is going to do that. Of course, we've been surprised by cork before. But I still think the smart money is on an internal failure. Given the history of COPVs, I'm suspicious, and if there really is a mismatch in thermal expansion, the super-chilled LOX may be making a bad problem worse.
I am surprised that no statement has been made about postponing future launches (or did I miss that?).
Someone posted this on reddit which I thought was interesting:
https://www.youtube.com/watch?v=tM-QlPAMLEc&feature=youtu.be&t=1m (https://www.youtube.com/watch?v=tM-QlPAMLEc&feature=youtu.be&t=1m)
The one and only thing that leads me to believe we could be looking at some kind of GSE failure (though not necessarily an external explosion, again jury's out on that one) is that SpaceX, it seems to me, is acting rather like it believes the anomaly does not reflect an inherent design or manufacturing weakness in stage 2 as-is. And I can imagine a few not-impossible of scenarios that could result in what saw happen that involve failures of propellant feed systems, helium feed systems and/or even hydraulic systems in the TEL.
So this was asked upthread a ways.
What do other vehicles use for helium bottles?
I noticed the atlas V uses helium bottles but I can't seem to find any info on their construction. They appear to be not inside of the tanks. Spaceflight101 just lists helium bottles. This diagram just shows their location for the rd180 and the rl10. The rl10 definitely isn't inside of a tank. Not sure about the lox tank for the rd180. Looks to be at the bottom of the lox tank.
http://www.ulalaunch.com/uploads/docs/Atlas500_Cutaway.pdf (http://www.ulalaunch.com/uploads/docs/Atlas500_Cutaway.pdf)
After looking into the topic over the past day, the Zenit launch vehicle, which appears to be the closest analog to the Falcon, uses titanium spheres for helium storage, submerged in the LOX tanks. Whether there are other materials in addition to titanium, such as some sort of overwrap, I have been unable to determine this. The Angara uses the same system.
I can not find another explicitly stated example of a launch vehicle which submerges COPV's in cryogenic Oxygen, although that doesn't mean there aren't any. From what I have found, vehicles which use COPV's for helium storage do not submerge them.
I really do hope Elon Musk sees this discussion thread.
I really do hope Elon Musk sees this discussion thread.I sure hope he ignores it and concentrates on the actual data he has in hand.
I really do hope Elon Musk sees this discussion thread.I sure hope he ignores it and concentrates on the actual data he has in hand.
Am I the only one who read ZachS09's comment and took it for a bit of irony? :)
3. Original discussion thingee now dubbed an obvious COPV. How does it blow out the side of the tank to the right, then end up shooting vertical centered on the tower, and loop to the left? Image 4 (produced by eeergo). Also, if you measure it's size in early frames, you see that it's asymmetric and much larger than a COPV would be, unless it's headed towards the camera at an amazing speed or has become a pancake.
The trajectory has been concerning me as far as labelling it a COPV is concerned.
Your composite image shows it originating from a point to the right of the vehicle - for it to have been part of the vehicle, it would have had to deflect off the erector to change the trajectory, otherwise it would have headed towards the right of the frame.
I'm with your later comment that it's highly unlikely to be a COPV deflecting off the erector. Regardless of the elasticity of various components, there are two problems with that being the COPV:
(1) The odds of it hitting a part of the erector that deflected it would be very slight - firstly, it would have had to hit an outer upright exactly evenly, otherwise it would have ended up embedded within the lattice of the structure. Secondly, had it not bounced off an upright and gone into the frame of the erector, it wouldn't come out. Thirdly, it would have had to pass through the clamping structure that holds the top of the vehicle - and that remained intact enough to hold the payload fairing for several seconds after.
(2) If you count the frames from the initial explosion to the point the object becomes visible flying out of the fireball, it's 20 (+/-1). Count forwards 20 frame from there and take a fix on the position and it's a couple of metres above the top of the fairing. That gives you an approximate distance travelled in the 20 frames after it becomes visible, so assuming a relatively constant velocity, the same distance back from the frame it was first visible should give you the approximate start point. (See attached image).
On that basis, it's unlikely this is a COPV (or anything else that was part of the vehicle). My guess would be this is part of the erector, liberated by the shockwave of the blast.
This image shows the emergence of the object frame by frame. Also, using a 17' fairing size as reference, the object appears to have a longest dimension of about 5 feet. If you look at the images to the left of where its appearance is obvious, it is obscuring parts of the tower several frames prior to your 20 frame point.
The COPV is about 22 inches in diameter and about 60 inches long. Just for reference.
For us metric minded people that's around 55cm in diameter and about 1.5m in length.
4)
Stress Rupture of the Composite Overwrap. Fiber-wrapped composite vessels differ from
metal vessels in that they experience an effect known as stress rupture, or static fatigue.
Stress rupture is a situation in which the composite experiences degradation, as a function
of time. This degradation results in a sudden structural failure of the pressurized vessel’s
composite overwrap, resulting in the rapid release of the vessel’s contents and the stored
energy of the pressurized gas – possibly causing serious injury and damage to the surroundings.
“Stress rupture is a sudden failure mode for [COPVs] that can occur at normal
operating pressures and temperatures. This failure mode can occur while at stress
levels below ultimate strength for [an] extended time. The failure mechanism is com-
plex, not well understood, [and] difficult to accurately predict or detect prior to failure.
The location and mechanism of triggering damage causing sudden failure is highly
localized, but at a random location. This location and extent of local damage has not
been able to be [reliably] detected by current [NDE] techniques prior to catastrophic
failure. Pressure, duration of time at pressure, and temperature experienced contribute
to the degradation of the fiber and/or the fiber-matrix interface, particularly around
accumulations of fiber breaks, and these increase the probability of COPV stress rupture.”
Just a quick note regarding the theories of origin based on the brightness of the fire/explosion.
Intensity doesn't correlate to origin, although on the surface that seems counter-intuitive. It simply indicates at what point the release of light energy is greatest. It's like the candle shown below, we know the wick is the source of ignition and the paraffin the source of fuel, but just based on the intensity of light we'd be led to believe the ignition is actually 2-3 inches above the candle.
*IF* the pipe running through the s-bend in the extendable section of the erector carries LOX (and not aircon),
In a rocket engine, you have pure O2 and fuel, in a ratio fairly close to balance (often slightly fuel rich to avoid corrosive nature of O2 rich exhaust gas)
In a rocket engine, you have pure O2 and fuel, in a ratio fairly close to balance (often slightly fuel rich to avoid corrosive nature of O2 rich exhaust gas)
There is no rocket engine in this case
*IF* the pipe running through the s-bend in the extendable section of the erector carries LOX (and not aircon),
There is no "if", it doesn't
The flash started higher up on the stage. Near the middle of it
*IF* the pipe running through the s-bend in the extendable section of the erector carries LOX (and not aircon),
There is no "if", it doesn't
Sure looks like it does carry LOX but not the main flow to the F9 but to a vent/overpressure relief plus Dragon or sat umbilical at the top of the strong back. Which suggests that if the joint in the "S" bend failed, it would vent what ever was in the pipe to atmo.
As the pipe to the left seems to carry aircon to the top of the strong back, to feed either a Dragon or sat, this would suggest the "S" bend pipe carries LOX to the top of the strong back to feed either a Dragon or sat if needed.
*IF* the pipe running through the s-bend in the extendable section of the erector carries LOX (and not aircon),
There is no "if", it doesn't
Sure looks like it does carry LOX but not the main flow to the F9 but to a vent/overpressure relief plus Dragon or sat umbilical at the top of the strong back. Which suggests that if the joint in the "S" bend failed, it would vent what ever was in the pipe to atmo.
As the pipe to the left seems to carry aircon to the top of the strong back, to feed either a Dragon or sat, this would suggest the "S" bend pipe carries LOX to the top of the strong back to feed either a Dragon or sat if needed.
No, the payloads don't need to be loaded with fuel or LOX when on the pad.
Would seem strongback fires have occurred before.
Would seem strongback fires have occurred before.
And, furthermore, that even when they impinge on the vehicle there is no effect.
Would seem strongback fires have occurred before.
And, furthermore, that even when they impinge on the vehicle there is no effect.
I've read most of the comments in this thread.
Currently 2 plauseible scenarios stand out and both have their faults:
Scenario 1: COPV failure.
Goes like this:
1. COPV (carbon fiber on top of aluminium) fails for unknown reason (may be delamination, may be something else)
2. It is safe to say that when carbon fiber fails, it has tremendous energy stored in it (high tensile strength and stiffness combined). That makes us assume, that possibly helium COPV (at ~6000psi) fails like in https://www.youtube.com/watch?v=5UdVnO10J3U, and then carbon fiber and epoxy will be dispersed as a fine dust into LOX, thereby turning immediate vincinity of the helium bottle onto an Oxyliquit.
3. Supersonic compression wave follows, heating up the mixture of fine carbon and epoxy dust in LOX to a point of detonation
4. Detonation occurs throwing pieces of S2 into different directions
5. 60ms after that behind still burning fireball, the now open LOX tank disperses large cloud of vaporizing oxygen
6. At the same time pressure wave propagates down the LOX pressure vessel destroying common bulkhead
7. RP-1 flows down the scene and COPV submerged in RP-1 tank gets ripped from the tank breaking the tubing to pressure regulator
8. RP-1 tank's COPV gets propelled upwards by releasing helium from broken tubing
the rest is not worth describing.
Issues with this scenario:
1. Why didn't the back side or the whole circumference of S2 burst open due to sharp pressure wave
2. Why wasn't the payload lifted by pressure release into LOX
3. Why the epicenter of initial detonation SEEMS to be just at or outside the surface of S2
4. Why did the COPV fail in first place
Scenario 2: External FAE or oxuliquit initiated event
1. For unknown reasons FAE mixture occurs near the S2. Other option - due to long time stay in oxygen rich environment either rubber stops, some padding. grease, insulation or whatnot turns into oxyliquit)
2. Static discharge (btw highly unlikely in such wet weather) initiates the inadvertently created explosive
3. Explosion occurs, rising pressure just outside the S2 to ~400 psi and temperature 4,500 to 5,400 °F
4. Pressure wave propagates inside the S2 tearing the outer wall open in process and ripping He COPV from it's supports.
5. Pressure wave reflects back from inside wall of S2 and together with pressurized LOX throws He COPV out from S2 at mild speeds
6. LOX tank's COPV gets propelled upwards by releasing helium from broken tubing
7. At the same time pressure wave propagates down the LOX pressure vessel destroying common bulkhead
8. RP-1 flows down the scene and COPV submerged in RP-1 tank gets ripped from the tank breaking the tubing to pressure regulator
Issues with this scenario:
1. There's a wind out there, so FAE is difficult, but not impossible to form
2. Such a cloud of dispersed fuel should have been seen (although the actual fireball may have been a lot smaller when measured from images due to lit surroundings.
3. WTF formed the FAE mixture in first place.
I've read most of the comments in this thread....
Currently 2 plauseible scenarios stand out and both have their faults:
Scenario 1: COPV failure.
Goes like this:
1. COPV (carbon fiber on top of aluminium) fails for unknown reason (may be delamination, may be something else)
2. It is safe to say that when carbon fiber fails, it has tremendous energy stored in it (high tensile strength and stiffness combined). That makes us assume, that possibly helium COPV (at ~6000psi) fails like in (see Youtube video in previous post), and then carbon fiber and epoxy will be dispersed as a fine dust into LOX, thereby turning immediate vincinity of the helium bottle onto an Oxyliquit.
3. Supersonic compression wave follows, heating up the mixture of fine carbon and epoxy dust in LOX to a point of detonation
4. Detonation occurs throwing pieces of S2 into different directions
5. 60ms after that behind still burning fireball, the now open LOX tank disperses large cloud of vaporizing oxygen
6. At the same time pressure wave propagates down the LOX pressure vessel destroying common bulkhead
7. RP-1 flows down the scene and COPV submerged in RP-1 tank gets ripped from the tank breaking the tubing to pressure regulator
8. RP-1 tank's COPV gets propelled upwards by releasing helium from broken tubing
the rest is not worth describing.
Issues with this scenario:
1. Why didn't the back side or the whole circumference of S2 burst open due to sharp pressure wave
2. Why wasn't the payload lifted by pressure release into LOX
3. Why the epicenter of initial detonation SEEMS to be just at or outside the surface of S2
4. Why did the COPV fail in first place
...
However, having looked at this more I am starting to question the COPV failure idea as well. This event seems too energetic for that in terms of burning gases already being apparent as the stage is intially breaching. To me this says either fts related or somehow there was a sudden fast fire already inside the lox tank nano or mili seconds before it breached.
...
The longer they stay clammed up the more I think it's either a real head-scratcher or they've got a fairly deep-seated problem with the vehicle (or both).well, consider the calendar: we're in the middle of a 3-day weekend, and they know from last year's experience that RTF is not a sprint.
Intensity doesn't correlate to origin, although on the surface that seems counter-intuitive. It simply indicates at what point the release of light energy is greatest. It's like the candle shown below, we know the wick is the source of ignition and the paraffin the source of fuel, but just based on the intensity of light we'd be led to believe the ignition is actually 2-3 inches above the candle.Maybe not exactly as what you meant, but while the 'diffraction crosshairs' seems to point at the right 'edge' of the visible rocket, it may well be that the actual brightest part was slightly at the 'back' of the S2, invisible from camera standpoint. The liberated 'thingee' could origin from that side as well and not be flying straight up, but up and farther away from the camera.
So, if I'm reading that graph right, say on the red line, there is a 1% chance of failure with 24 hours of use at 75% load on the composite overwrap. That means to improve the odds, you need to either reduce the time the vessel is loaded (less test time?), or reduce the load on the overwrap (thicker metal, lower pressure?). Is that the right way to read that graph?
at 4 kelvin helium is liquid?
Is there a pressure relief valve almost exactly at the origin of the fire (if you believe the lens flare cross points to the right place)?
See venting during the JCSAT-16 static fire, which is exactly the same angle as the AMOS-6 video: https://www.youtube.com/watch?v=rK9Xz3ZqBG4&feature=youtu.be&t=2m18s
When the strongback is fully retracted maybe no effect. Might just be a different result if the strongback is closely coupled to the F9 and occurs where the 2nd stage LOX tank vent is and the LOX tank is being vented (valve open).
When the strongback is fully retracted maybe no effect. Might just be a different result if the strongback is closely coupled to the F9 and occurs where the 2nd stage LOX tank vent is and the LOX tank is being vented (valve open).
For the sake of neatness, here's the vent on the second stage, seen at the JCSAT14 static fire.
For the correlation (not causation!) list, this is about the height of the brightest point of the initial explosion.
...
For the sake of neatness, here's the vent on the second stage, seen at the JCSAT14 static fire.
For the correlation (not causation!) list, this is about the height of the brightest point of the initial explosion.
Just adjacent to that LOX vent is the "S" bend in the RP-1 supply pipe.
Just adjacent to that LOX vent is the "S" bend in the RP-1 supply pipe.
Just adjacent to that LOX vent is the "S" bend in the RP-1 supply pipe.
That is not what that is. That S bend is *above* the level of the second stage LOX umbilical. If you look at other photos, you'll see that that line goes onto the payload shroud, which means it cannot be RP1 or LOX. It's an air conditioning duct, as Jim said.
IMHO, you're right on the Lox vent being close to that S bend.
So, if I'm reading that graph right, say on the red line, there is a 1% chance of failure with 24 hours of use at 75% load on the composite overwrap. That means to improve the odds, you need to either reduce the time the vessel is loaded (less test time?), or reduce the load on the overwrap (thicker metal, lower pressure?). Is that the right way to read that graph?
For Kevlar® COPVs, the manufacturer can compute the stress rupture reliability using a Weibull model because a large, robust database exists. Un- fortunately, as of the writing of this paper, there is not a similar database for carbon. Two NASA independent stress rupture test programs are currently under way that should provide additional data availability in 2013 for analysis. Until that time, the NESC and JSC Engineering recommend that the carbon fiber strain remain at or below 50% of the ultimate strength. Based on industry- wide experience, the risk of stress rupture at a strain ratio of 50% is minimal for short-duration space missions.
When I look at this picture:It goes to the very top of T/E, apparently to some equipment there and then umbilicals to the P/L.
https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=30981.0;attach=1366202;sess=14795
the tube is not connected to payload shroud in any ways.
Just adjacent to that LOX vent is the "S" bend in the RP-1 supply pipe.
That is not what that is. That S bend is *above* the level of the second stage LOX umbilical. If you look at other photos, you'll see that that line goes onto the payload shroud, which means it cannot be RP1 or LOX. It's an air conditioning duct, as Jim said.
IMHO, you're right on the Lox vent being close to that S bend.
When I look at this picture:
https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=30981.0;attach=1366202;sess=14795
the tube is not connected to payload shroud in any ways.
Just adjacent to that LOX vent is the "S" bend in the RP-1 supply pipe.
That is not what that is. That S bend is *above* the level of the second stage LOX umbilical. If you look at other photos, you'll see that that line goes onto the payload shroud, which means it cannot be RP1 or LOX. It's an air conditioning duct, as Jim said.
IMHO, you're right on the Lox vent being close to that S bend.
When I look at this picture:
https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=30981.0;attach=1366202;sess=14795
the tube is not connected to payload shroud in any ways.
The payload in the pic is a Dragon. It is not a payload shroud, so no shroud AC duct attached.
For a pic of that line (With the S in it) going into the Thiacom payload shroud, this link should work;
http://www.americaspace.com/wp-content/uploads/2014/01/1515011_694655020564843_986350026_n.jpg
That fact that line goes into a payload shroud means it cannot be RP1 (or for that matter, Lox).
Hrmmm... Looks like there are two AC ducts; one in, one out? Is the S-bend is on the out (return) duct and, hypothetically, there was a hydrazine leak in the payload, and if those AC ducts leak a bit (which normally would not be a problem due to positive pressurization... that S-bend, if a bit leaky, would put hypothetical hydrazine vapor in contact with the O2 being vented at about the area of the apparent locus of the event.
Hrmmm... Looks like there are two AC ducts; one in, one out? Is the S-bend is on the out (return) duct and, hypothetically, there was a hydrazine leak in the payload, and if those AC ducts leak a bit (which normally would not be a problem due to positive pressurization... that S-bend, if a bit leaky, would put hypothetical hydrazine vapor in contact with the O2 being vented at about the area of the apparent locus of the event.
Hrmmm... Looks like there are two AC ducts; one in, one out? Is the S-bend is on the out (return) duct and, hypothetically, there was a hydrazine leak in the payload, and if those AC ducts leak a bit (which normally would not be a problem due to positive pressurization... that S-bend, if a bit leaky, would put hypothetical hydrazine vapor in contact with the O2 being vented at about the area of the apparent locus of the event.
Ah, here we go again. The payload's fault. Anything but the vehicle.
Anything.
Hrmmm... Looks like there are two AC ducts; one in, one out? Is the S-bend is on the out (return) duct and, hypothetically, there was a hydrazine leak in the payload, and if those AC ducts leak a bit (which normally would not be a problem due to positive pressurization... that S-bend, if a bit leaky, would put hypothetical hydrazine vapor in contact with the O2 being vented at about the area of the apparent locus of the event.
Ah, here we go again. The payload's fault. Anything but the vehicle.
Anything.
No. It's more like "could we exclude Scenario 2 (FAE)?". The answer is that we couldn't. Both scenarios are plausible, though, Scenario 1 (COPV) seems more likely.
In this case, one plausible scenario is that this leaked hydrazine cloud gets connected to some rusty part of strongback and flashes (hydrazine autoignition temperature on rust is 24C)
Hrmmm... Looks like there are two AC ducts; one in, one out? Is the S-bend is on the out (return) duct and, hypothetically, there was a hydrazine leak in the payload, and if those AC ducts leak a bit (which normally would not be a problem due to positive pressurization... that S-bend, if a bit leaky, would put hypothetical hydrazine vapor in contact with the O2 being vented at about the area of the apparent locus of the event.
Ah, here we go again. The payload's fault. Anything but the vehicle.
Anything.
Also, even if it was a hydrazine leak in AMOS, that does not get SpaceX off the hook - it might well be their fault due to a mistake in processing/handling of the payload.
the tube is not connected to payload shroud in any ways.
Which makes sense since there is no "payload shroud" in that picture.
Wow. I did not realize Ariane 5 carried 168Kg of liquid Helium in the LOX tank. I know it's the pressurizing gas of choice but always thought keeping it liquid would be just too tough in a launch environment.at 4 kelvin helium is liquid?
At 4 K and 23 bar, Helium is liquid and not supercritical. According to the attached pamphlet, Ariane V uses a liquid Helium tank for pressurisation, at 4.2 K. The liquid Helium would be heated by heat from the engine, where it would be used to pressurise the tanks. Not sure why that previous link said supercritical, but that is clearly incorrect, unless they somehow confused the liquid tank with the gaseous Helium tanks that are also used.
Wow. I did not realize Ariane 5 carried 168Kg of liquid Helium in the LOX tank.
Ooops. The pamphlet on the end of Steve's post said the LHe pressurizes the LOX tank. I conflated that with being in the LOX tank, which is where they are often put.Wow. I did not realize Ariane 5 carried 168Kg of liquid Helium in the LOX tank.
Are you sure it's located in the LOX tank? It doesn't look that way to me.
Just adjacent to that LOX vent is the "S" bend in the RP-1 supply pipe.
That is not what that is. That S bend is *above* the level of the second stage LOX umbilical. If you look at other photos, you'll see that that line goes onto the payload shroud, which means it cannot be RP1 or LOX. It's an air conditioning duct, as Jim said.
IMHO, you're right on the Lox vent being close to that S bend.
When I look at this picture:
https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=30981.0;attach=1366202;sess=14795
the tube is not connected to payload shroud in any ways.
In absence of any data on our part, any scenarios that require multiple failures (and the probability of chained failures drops off exponentially) like the above copious hydrazine leak on P/L *and* AC duct leak will inevitably look contrived.
Which reminds me, did anyone postulate the scenario of a strut failure on CRS-7 in the vast speculations on this forum?
My point is that complex failure mechanisms seem to be constructed here (for the apparent purpose of getting F9 off the hook) while there is probably a large number of single failure mechanisms we haven't even thought of.
Yes, theoretically, we as a forum community cannot exclude any of the more complex ones, but I feel Occam's razor probably has something to say about them.
Two tubes run to the top of the strongback. One stops where the 2ns stage umbilical attaches to the strongback. Suggest the RP-1 goes to the top of the strongback as if needed the RP-1 can vent / dump from there. Of course the dumped RP-1 can cause problems.
Wow. I did not realize Ariane 5 carried 168Kg of liquid Helium in the LOX tank. I know it's the pressurizing gas of choice but always thought keeping it liquid would be just too tough in a launch environment.at 4 kelvin helium is liquid?
At 4 K and 23 bar, Helium is liquid and not supercritical. According to the attached pamphlet, Ariane V uses a liquid Helium tank for pressurisation, at 4.2 K. The liquid Helium would be heated by heat from the engine, where it would be used to pressurise the tanks. Not sure why that previous link said supercritical, but that is clearly incorrect, unless they somehow confused the liquid tank with the gaseous Helium tanks that are also used.
I think it's another testimony to how robust these structures are that none of them has ever failed in flight, given the massive (explosive) volume expansion that would take place if its insulation was punctured.
Sadly there is always a first time for everything and time will tell if this is that time.
Two tubes run to the top of the strongback. One stops where the 2ns stage umbilical attaches to the strongback. Suggest the RP-1 goes to the top of the strongback as if needed the RP-1 can vent / dump from there. Of course the dumped RP-1 can cause problems.
Suggest that this is totally wrong. Suggest that no RP-1 goes to the top of the strongback. Suggest that RP-1 is never "vented" it is drained (and filled) through the umbilical at the base of the second stage. Suggest that the fires seen on the strongback are by RP-1 draining from the disconnected umbilical which is set on fire by the exhaust of the engines as the vehicle rises.
Launch pads do not vent combustible fluids freely into the atmosphere. LH2 powered vehicles have the boiled off GH2 siphoned off and burned off safely at a distance. RP-1 vehicles do not vent RP-1 because there is no reason to do so. Period.
Launch pads do not vent combustible fluids freely into the atmosphere. LH2 powered vehicles have the boiled off GH2 siphoned off and burned off safely at a distance. RP-1 vehicles do not vent RP-1 because there is no reason to do so. Period.
So what is vented to the right, falls down and is ignited in the video? Sure looks like RP-1 to me. Then I wonder why there is a vent on the very top of the strongback?
With respect, the video and the vent location suggest otherwise.
Please remember we are dealing with fluids chilled their max density point. So maybe super chilled RP-1, when it warms and expands a bit and may need to be vented.
Yes, but note that time scale is a logarithm and the only data points were for a 50% chance of failure and for a day to a year failure chance you need to run it t 65% of ultimateYou misread the plot. The points are the median values of many tests that failed within the yellow bands. So at 85% of rupture their could be more than 20 actual tests.
Yes, but note that time scale is a logarithm and the only data points were for a 50% chance of failure and for a day to a year failure chance you need to run it t 65% of ultimateYou misread the plot. The points are the median values of many tests that failed within the yellow bands. So at 85% of rupture the could be more than 20 actual tests.
What the chart does not show is the effect of multiple cycles at a given load. Holding at 40% rupture for 25 years is not what happens here.
Launch pads do not vent combustible fluids freely into the atmosphere. LH2 powered vehicles have the boiled off GH2 siphoned off and burned off safely at a distance. RP-1 vehicles do not vent RP-1 because there is no reason to do so. Period.
So what is vented to the right, falls down and is ignited in the video? Sure looks like RP-1 to me. Then I wonder why there is a vent on the very top of the strongback?
With respect, the video and the vent location suggest otherwise.
Please remember we are dealing with fluids chilled their max density point. So maybe super chilled RP-1, when it warms and expands a bit and may need to be vented.
Please stop. No sane person would ever vent RP-1 fumes into oxygen-rich environment near $300 mil vulnerable equipment full of dangerous flammables. In extreme "if", this could be some emergency vent, but I would be very surprised if it's that.
Please remove your "I have to prove my point" hat and wear "curios to what may be the actual likely reason" hat instead.
Super-chilled RP-1 is a viscous substance that is the least "excess venting" requiring flammable one can find.
So what was clearly vented from the top of the strongback, fell down until it found some heat and maybe LOX and caught fire? You can't avoid what the video clearly shows happened.
As far as I know vented LOX does not fall down as the vented white vapour does in the video. The only thing that I know of, that was on that strongback, that would form a heavy white vapour upon venting, fall down and then ignite is RP-1. What else can it be?
I agree that there *appears* to be a vent on the top of the strongback, although this could be a fitting to allow something to be pumped into the system when it is on the ground.
It would be useful if we knew what this was...
I'm not sure that whatever many have vented from the top of the strongback was whatever ignited - I would think a more likely candidate would be residual RP-1 from the fuelling line(s).
Perhaps this nozzle in top is fire suppression head and the whole tube is for spraying rocket with fire suppression liquid, should there be RP-1 leak and develop fire. Then all that (mysterious tube, mysterious spray-nozzle) would make sense as well as the eventual purge from the tube (tube should be prefilled to enable quick reaction times).
To follow up a previous post.
A slight mis-adjustment of the top clamps allowed excess weight to be placed on the support fixture at the common bulkhead position. That caused a slight deformation of the tank body inward, after payload supports were removed and while vehicle was being raised to vertical. This was NOT enough to structurally damage the tank but WAS enough to crack a bolt holding one of the COPV's in place. Then the cryogenic cooling contracted the tank enough to shear the bolt completely. Other bolts and struts were strong enough to hold the COPV in place so that the unrestricted strut became a "dagger" that pierced the common bulkhead. Scraping as it pierced caused a spark that ignited the mixture around the hole.
Or not.
Perhaps this nozzle in top is fire suppression head and the whole tube is for spraying rocket with fire suppression liquid, should there be RP-1 leak and develop fire. Then all that (mysterious tube, mysterious spray-nozzle) would make sense as well as the eventual purge from the tube (tube should be prefilled to enable quick reaction times).
The "vent???" is pointed tangential to the F9 and not at the F9.
It would make sense to have a fire fighting system installed along the strongback.
Just a random thought that I haven't seen mentioned yet: the concept that the explosion could have been driven by nothing more than the combusion of LOX with *the tank itself*.
Aluminum alloys are generally LOX compatible. *Generally*. But it requires an intact oxide layer. LOX is, for example, not compatible with freshly polished aluminum. And once a burn begins, it's self-sustaining and very aggressive.
Any chance that there was a damaged or even never formed oxide layer inside?
Contamination also comes across as possibilities, because there's a lot of things considered incompatible with LOX - greases, lubricants, most solvents, most plastics, and on and on. Most are not hypergolic, but they can go off with an ignition source, including mere impact. LOX tanks must be clean, both on the vehicle end, the delivery end, and everything in-between. But *not* cleaned to the point of removing the protective oxide layer shortly before filling.
Just some thoughts to add to the conversation.
Perhaps this nozzle in top is fire suppression head and the whole tube is for spraying rocket with fire suppression liquid, should there be RP-1 leak and develop fire. Then all that (mysterious tube, mysterious spray-nozzle) would make sense as well as the eventual purge from the tube (tube should be prefilled to enable quick reaction times).
The "vent???" is pointed tangential to the F9 and not at the F9.
It would make sense to have a fire fighting system installed along the strongback.
I think that 'vent' is used during the dragon late load, to supply clean air to the 'cabin'
http://blogs.nasa.gov/spacex/wp-content/uploads/sites/227/2016/04/spacex8-latecargoload-1024x683.jpg (http://blogs.nasa.gov/spacex/wp-content/uploads/sites/227/2016/04/spacex8-latecargoload-1024x683.jpg)
Perhaps this nozzle in top is fire suppression head and the whole tube is for spraying rocket with fire suppression liquid, should there be RP-1 leak and develop fire. Then all that (mysterious tube, mysterious spray-nozzle) would make sense as well as the eventual purge from the tube (tube should be prefilled to enable quick reaction times).
The "vent???" is pointed tangential to the F9 and not at the F9.
It would make sense to have a fire fighting system installed along the strongback.
I think that 'vent' is used during the dragon late load, to supply clean air to the 'cabin'
http://blogs.nasa.gov/spacex/wp-content/uploads/sites/227/2016/04/spacex8-latecargoload-1024x683.jpg (http://blogs.nasa.gov/spacex/wp-content/uploads/sites/227/2016/04/spacex8-latecargoload-1024x683.jpg)
This one solves the matter with this tube. And again, Jim was right - no LOX, no RP-1 in there.
Perhaps this nozzle in top is fire suppression head and the whole tube is for spraying rocket with fire suppression liquid, should there be RP-1 leak and develop fire. Then all that (mysterious tube, mysterious spray-nozzle) would make sense as well as the eventual purge from the tube (tube should be prefilled to enable quick reaction times).
The "vent???" is pointed tangential to the F9 and not at the F9.
It would make sense to have a fire fighting system installed along the strongback.
I think that 'vent' is used during the dragon late load, to supply clean air to the 'cabin'
http://blogs.nasa.gov/spacex/wp-content/uploads/sites/227/2016/04/spacex8-latecargoload-1024x683.jpg (http://blogs.nasa.gov/spacex/wp-content/uploads/sites/227/2016/04/spacex8-latecargoload-1024x683.jpg)
This one solves the matter with this tube. And again, Jim was right - no LOX, no RP-1 in there.
@ Rei: The oxide layer on aluminum tends to "heal" as soon as it's exposed to air.
Atlas, Titan I, R-7, Zenit....they all had/have aluminum LOX tanks which tends to suggest that this isn't any problem.
Contamination might be a possibility, but I think that is way down the line. It would mean that there was something seriously wrong with SpaceX's processing.
This one solves the matter with this tube. And again, Jim was right - no LOX, no RP-1 in there.
Another useful photo showing the plumbing - note this is F9 1.1 and there are a few bits 'missing' from the erector compared to its most recent format.
@ Rei: The oxide layer on aluminum tends to "heal" as soon as it's exposed to air.
Indeed. But there are two aspects to that.
1) Air
2) Time
What gas is in the tank during transport / storage / erection? Air, or something inert like nitrogen? And how sure are we that due to the stress of erecting or loading the rocket that there was no damage to the oxide layer?QuoteAtlas, Titan I, R-7, Zenit....they all had/have aluminum LOX tanks which tends to suggest that this isn't any problem.
It certainly suggests that it would not be a common problem - but not that we can rule it out, as each vehicle has its own manufacture, transport, erection, etc properties. It's also worthy of note that none of those rockets used densified LOX. There's actually rather limited experience with it.QuoteContamination might be a possibility, but I think that is way down the line. It would mean that there was something seriously wrong with SpaceX's processing.
I agree. I'm just presenting this possibility, to point out that the presence of combustion within the LOX tank does not inherently imply contact between the LOX and RP1.
Looking at strongback photos, it looks like the top part is mechanically decoupled, to probably allow for this adjustment.
Anyone have any history on how many cycles the second stage has gone though since manufacture?Not a number, but less than S1-024.
Anyone have any history on how many cycles the second stage has gone though since manufacture?Rough guess - this was the second prop load on the tankage. 1st for acceptance testing at McGregor, and then the static fire attempt.
Making up ideas to "absolve" the vehicles is a smaller sin than overlooking possibilities because of that.Hrmmm... Looks like there are two AC ducts; one in, one out? Is the S-bend is on the out (return) duct and, hypothetically, there was a hydrazine leak in the payload, and if those AC ducts leak a bit (which normally would not be a problem due to positive pressurization... that S-bend, if a bit leaky, would put hypothetical hydrazine vapor in contact with the O2 being vented at about the area of the apparent locus of the event.
Ah, here we go again. The payload's fault. Anything but the vehicle.
Anything.
Peter B. de Selding @pbdes 1h1 hour agohttps://twitter.com/pbdes/status/772795118143303680 (https://twitter.com/pbdes/status/772795118143303680)
Spacecom CEO David Pollack on how he learned his Amos-6 sat was under the smoke cloud from Cape Canaveral on Sept 1.
Thanks, that's all I would figure at this point as well unless they did more in Texas...Anyone have any history on how many cycles the second stage has gone though since manufacture?Rough guess - this was the second prop load on the tankage. 1st for acceptance testing at McGregor, and then the static fire attempt.
This one solves the matter with this tube. And again, Jim was right - no LOX, no RP-1 in there.
Another useful photo showing the plumbing - note this is F9 1.1 and there are a few bits 'missing' from the erector compared to its most recent format.
Wonderful photo. Thanks.
Is the combined Aircon & LOX header unit, as per the attached, maybe "The Thingy" that shot up into the air from the strongback?
The line you have labeled as a LOX line going up to what you have labeled as a combined LOX/AC header unit is, as again has been noted by people who have worked on those lines and who know and are not just speculating, is an AC return line. Again, just to put the matter to rest, this is not a LOX line. No LOX lines go farther up the TEL than the base of stage 2.
Now, if, say, the RP-1 umbilical that runs to the bottom of stage 2 were to have suffered a small leak that was located just such that it sprayed RP-1 in an invisible cloud up to the level of the LOX vents, near where the flash was seen, then maybe I could see a FAE event happening. But it was a windy day...
1. Al tank holding supercooled LOX will NOT self-combust due to simple reasons - even if some patch of aluminium gets constantly scrubbed:
1.1. This Al oxide layer is one of the hardest substances known to man and does not come off easily
1.2. Any heat build-up before combustion will be absorbed by sheer mass of supercooled LOX
2. Densified LOX is probalby even less susceptible to causing Al-O2 fire due to general rule - lower temperature, slower reactions
3. I have never heard about LOX containing Al tank to burst to fire without initiation ... AFAIK, you can even have Al slurry in LOX and it still won't autoignite.
*IF* the pipe running through the s-bend in the extendable section of the erector carries LOX (and not aircon),
There is no "if", it doesn't
Sure looks like it does carry RP-1.
Would seem strongback fires have occurred before.
Does anyone have an idea what data rate the 3000 channels of data were recording at? I would assume some channels video and some GSE equipment would be low ( 30 to 100 Hz).
Just trying to understand what kind of resolution Space X will see during the 30-35 miliseconds. Got to believe SpaceX has all the digital data reviewed by now and have a good idea as to the source of the problem if not the reason.
Just adjacent to that LOX vent is the "S" bend in the RP-1 supply pipe.
That is not what that is. That S bend is *above* the level of the second stage LOX umbilical. If you look at other photos, you'll see that that line goes onto the payload shroud, which means it cannot be RP1 or LOX. It's an air conditioning duct, as Jim said.
IMHO, you're right on the Lox vent being close to that S bend.
When I look at this picture:
https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=30981.0;attach=1366202;sess=14795
the tube is not connected to payload shroud in any ways.
In this case, one plausible scenario is that this leaked hydrazine cloud gets connected to some rusty part of strongback and flashes (hydrazine autoignition temperature on rust is 24C)
Three tubes come up from the bottom. One stops where the 2ns stage umbilical attaches to the strongback. Two tubes continue up and run to the top of the strongback. Suggest the RP-1 goes to the top of the strongback as if needed the RP-1 can vent / dump from there. Of course the dumped RP-1 can cause problems.
Interesting the initial flash of the 2 events looks very similar. SlowMo video attached.
Fairly serious very top of the strongback vent is seen.
Also, to be clear, even if it was a hydrazine leak, how would that get SpaceX off the hook any more than a strut
Note in post 1349 how small the support fixture by the common bulkhead is. Note also the crescent connection between that structure and the upper clamps. It would make sense that these are small because they are only intended to support about 1/2 of stage 2. But also note it is right in the section that is the portion of the TEL that can be adjusted for height. Could it be that they simulated compressional loads properly but maybe underestimated the rotational load on those struts with a very heavy payload? (Could the Fairing have additional recovery system weight?)
Guessing at a list of things that might be different from prior launches.
If hydrazine was released from the satellite into the fairing, then flushed out by AC, it would end up in the very AC return line that many people are holding suspect.
Does that AC return duct go all the way down to ground, or does it vent the removed gases at some higher altitude?
Does anyone have an idea what data rate the 3000 channels of data were recording at? I would assume some channels video and some GSE equipment would be low ( 30 to 100 Hz).
Just trying to understand what kind of resolution Space X will see during the 30-35 miliseconds. Got to believe SpaceX has all the digital data reviewed by now and have a good idea as to the source of the problem if not the reason.
I would think SpaceX already has the data that illuminates what happened. However, you're right, there is proximate cause and then there is root cause.
The data likely has shown them what the proximate cause was -- what was happening that made the rocket go boom. As to what began the chain of events that led to the proximate cause, that's the item that will take longer to define. And that's what they need to get down to before they can even define their next steps in making the system safe to fly again.
The one thing I will say is this --it is not the exact same causation path that happened on CRS-7. This was a sudden, abrupt failure, while CRS-7's overpressurization event occurred over a period of up to 10 seconds. If this was an overpressurization event, it occurred far, far more rapidly. So, people who are sitting back and dispensing their disgust about how SpaceX failed to fix the same problem that took down CRS-7 should just stop, since it's impossible that this could be the same problem.
It could possibly be a different problem in the same system, but it's not the same problem, has a different proximate cause, and almost certainly has a different root cause.
Bear in mind that the stages are very strong - strong enough to be trucked across the country, tested, launched and in the case of the first stage, landed. Those stresses are much more than being sat on the erector and taken vertical a couple of times.
Three tubes come up from the bottom. One stops where the 2ns stage umbilical attaches to the strongback. Two tubes continue up and run to the top of the strongback. Suggest the RP-1 goes to the top of the strongback as if needed the RP-1 can vent / dump from there. Of course the dumped RP-1 can cause problems.
Interesting the initial flash of the 2 events looks very similar. SlowMo video attached.
Fairly serious very top of the strongback vent is seen.
No, just stop. It is an AC duct
If hydrazine was released from the satellite into the fairing, then flushed out by AC, it would end up in the very AC return line that many people are holding suspect.
Does that AC return duct go all the way down to ground, or does it vent the removed gases at some higher altitude?
There is no return duct. It is a single pass system. It vents out of the fairing near the bottom
Isn't that just one wound up to have leeway when the strong back moves back?If hydrazine was released from the satellite into the fairing, then flushed out by AC, it would end up in the very AC return line that many people are holding suspect.
Does that AC return duct go all the way down to ground, or does it vent the removed gases at some higher altitude?
There is no return duct. It is a single pass system. It vents out of the fairing near the bottom
This surely looks like 2 separate ducts going into the fairing.
(http://i.imgur.com/24r2llc.jpg)
Edit: Oops. Big image.
Bear in mind that the stages are very strong - strong enough to be trucked across the country, tested, launched and in the case of the first stage, landed. Those stresses are much more than being sat on the erector and taken vertical a couple of times.
And if your/their strength assumptions are in the slightest way wrong the vehicle goes boom -
- which it did.
Isn't that just one wound up to have leeway when the strong back moves back?If hydrazine was released from the satellite into the fairing, then flushed out by AC, it would end up in the very AC return line that many people are holding suspect.
Does that AC return duct go all the way down to ground, or does it vent the removed gases at some higher altitude?
There is no return duct. It is a single pass system. It vents out of the fairing near the bottom
This surely looks like 2 separate ducts going into the fairing.
[snip /]
Edit: Oops. Big image.
The Yellow line ends at the bottom of the interstage and connects to one of the 2 shiny umbilical feeds that connect to the 2nd stage.
The Orange line does appear to be a A/C line.
The Green line connects to the other 2nd stage shiny umbilical that connects to the 2nd stage but doesn't appear to stop at the bottom of the interstage. It appears to continue to the top of the strongback.
Please show where the Green line stops being a supply line to the 2nd stage and becomes a return A/C duct as I can't see it. Maybe I should toss my engineering degree and 45 years of engineering experience.
Still looks like 2 ducts.
In this case, one plausible scenario is that this leaked hydrazine cloud gets connected to some rusty part of strongback and flashes (hydrazine autoignition temperature on rust is 24C)
The Yellow line ends at the bottom of the interstage and connects to one of the 2 shiny umbilical feeds that connect to the 2nd stage.
The Orange line does appear to be a A/C line.
The Green line connects to the other 2nd stage shiny umbilical that connects to the 2nd stage but doesn't appear to stop at the bottom of the interstage. It appears to continue to the top of the strongback.
Please show where the Green line stops being a supply line to the 2nd stage and becomes a return A/C duct as I can't see it. Maybe I should toss my engineering degree and 45 years of engineering experience.
You may have missed my query about that duct, so attached again.
It does feed / join the feed to the first stage, but then comes to a end about halfway down the strongback - i.e. it can not be a supply from the ground.
The image you're using isn't thoroughly helpful as it doesn't show that the pipe marked in green doesn't go to the bottom of the erector.
Given the stresses the vehicle goes through in use, I think SpaceX's strength 'assumptions' would have to be a bit more wrong than the 'slightest way' for the vehicle to explode without warning on the pad because the strongback supports are set up wrong.
I'm still looking at at brittle fracture of material of either FSW at the common bulkhead or at the bottom COPV mount at the tank side wall. It could be cryro cycling or material dislocation. A failure in that area would cause RP-1/LOX mixing and the possible kinetic energy for ignition. It is an event that happens very fast...
Yes, it's just for a reference point for my thoughts... Feel free to update the image...I'm still looking at at brittle fracture of material of either FSW at the common bulkhead or at the bottom COPV mount at the tank side wall. It could be cryro cycling or material dislocation. A failure in that area would cause RP-1/LOX mixing and the possible kinetic energy for ignition. It is an event that happens very fast...
Note: this looks like a v1.0 second stage to me.
I'm still looking at at brittle fracture of material of either the FSW at the common bulkhead or at the bottom COPV mount at the tank side wall. It could be cryro cycling or material dislocation. A failure in that area would cause RP-1/LOX mixing and the possible kinetic energy for ignition. It would an event that happens very fast...
Yes, I agree Herb with that as well and could have produced a vibration or shock fatigue along the transport. I believe that Doug may have said thing along the same lines as well with the Apollo 13 LOX tank handling. Multiple causes including a bad material batch or start/stop FSW spot during manufacture could have revealed itself during erection and prop load temps, pressures and COPV upward strain.I'm still looking at at brittle fracture of material of either the FSW at the common bulkhead or at the bottom COPV mount at the tank side wall. It could be cryro cycling or material dislocation. A failure in that area would cause RP-1/LOX mixing and the possible kinetic energy for ignition. It would an event that happens very fast...
Hmm, the bottom of that COPV mount you have circled in red does appear to be around the approximate centroid of the flash seen in the video.
I have no pet theory here, as amusing as it is to watch people with random backgrounds try to correct Jim and nitpick to support their own. That said, I do wonder - personally - if the root cause of this might come down a handling mishap with S2 somewhere along the way days, weeks or even months ago, such as jarred or dropped tank in the factory (say a jolt of 2" - 3" in placing on the cradle for transport or assembly jig, or the over-the-road transport truck having a minor collision along the route such as bumping a concrete post as a truck stop)? Alternately, perhaps a bit of manufacturing re-work might have been required during assembly at one of the COPV mounts which was performed in a defective manner (something like that brought down an entire 747 full of people in Japan once) ... In other words, a seemingly minor event somewhere along the that seemed of no consequence but which eventually resulted in a major mishap.
I'm still looking at at brittle fracture of material of either the FSW at the common bulkhead or at the bottom COPV mount at the tank side wall. It could be cryro cycling or material dislocation. A failure in that area would cause RP-1/LOX mixing and the possible kinetic energy for ignition. It would an event that happens very fast...
Give me a side view cutaway please or I will reject your reality and replace it with my own... ;DI'm still looking at at brittle fracture of material of either the FSW at the common bulkhead or at the bottom COPV mount at the tank side wall. It could be cryro cycling or material dislocation. A failure in that area would cause RP-1/LOX mixing and the possible kinetic energy for ignition. It would an event that happens very fast...
You do realize the drawing your working from does not match reality in many ways... ;)
Yes it happened to the Russians several times. The most famous one is probably the "Nedelin disaster" with an early ICBM, which resulted in a high number of fatalities too.
But it could be strong in every possible direction & motion EXCEPT a pivot around that frighteningly tiny support fixture. It would have never been seen with non-payload static fires or even Dragon static fires and launches - they are not heavy enough, or present a long enough lever arm to have an effect. So just what, maybe 5 launches where they were close but dodged the bullet. Just like STS dodged the foam issue for 106 launches. How is this less likely than not testing COPV's enough to guarantee they won't explode?
But it wasn't a fire. It was a very neat and clean detonation, which subsided before the main fire erupted.
Any scenario that starts with internal mixing of RP1 and O2, I'd think, would result in a much much larger detonation, and it wouldn't subside - it would generate more mixing as it went, and it would also obliterate the payload.
We must always bear in mind that it could be an unfortunate combination of design, materials, forces, events, conditions and not a smoking gun...But it could be strong in every possible direction & motion EXCEPT a pivot around that frighteningly tiny support fixture. It would have never been seen with non-payload static fires or even Dragon static fires and launches - they are not heavy enough, or present a long enough lever arm to have an effect. So just what, maybe 5 launches where they were close but dodged the bullet. Just like STS dodged the foam issue for 106 launches. How is this less likely than not testing COPV's enough to guarantee they won't explode?
That support is one of a pair - the second one is at the level of the 'claw' immediately under the fairings.
The pair of supports are mounted on a frame which appears to be pivoted at its centre - i.e. if the loading on one of the supports is disproportionate, it will give a little and the other one will be pressed against the stage.
No doubt someone could come up with a failure mode based on this ;)
Once the vehicle is located on the erector frame, there will be no unexpected forces. As far as I'm aware, the vehicle is lifted horizontally and lowered horizontally onto the erector, so I don't quite see how it can experience forces sufficient to damage it - unless it's been dropped or badly abused in transit.
But it wasn't a fire. It was a very neat and clean detonation, which subsided before the main fire erupted.
Any scenario that starts with internal mixing of RP1 and O2, I'd think, would result in a much much larger detonation, and it wouldn't subside - it would generate more mixing as it went, and it would also obliterate the payload.
If it was an internal event, it managed to burst the skin without shredding the stage, showed the detonation outside, ran its course, and then the shockwave destroyed the stage (which might have been weakened by the first event).
It all happens between the two critical frames of the youTube video... The first shows nothing, not even deformation or spray, the second shows a detonation already many meters across. 30 ms is a long time in explosions...
For the sake of neatness, here's the vent on the second stage, seen at the JCSAT16 static fire.
For the correlation (not causation!) list, this is about the height of the brightest point of the initial explosion.
Give me a side view cutaway please or I will reject your reality and replace it with my own... ;DI'm still looking at at brittle fracture of material of either the FSW at the common bulkhead or at the bottom COPV mount at the tank side wall. It could be cryro cycling or material dislocation. A failure in that area would cause RP-1/LOX mixing and the possible kinetic energy for ignition. It would an event that happens very fast...
You do realize the drawing your working from does not match reality in many ways... ;)
1. The Green line connects to the other 2nd stage shiny umbilical that connects to the 2nd stage but doesn't appear to stop at the bottom of the interstage. It appears to continue to the top of the strongback.
2. Please show where the Green line stops being a supply line to the 2nd stage and becomes a return A/C duct as I can't see it.
3. Maybe I should toss my engineering degree and 45 years of engineering experience.
This surely looks like 2 separate ducts going into the fairing.
The left feed pipe to the 2nd stage umbilicals does stop at the bottom of the interstage but the right feed pipe does not stop at the bottom of the interstage.
I'll just give Elon a call then... ;DGive me a side view cutaway please or I will reject your reality and replace it with my own... ;DI'm still looking at at brittle fracture of material of either the FSW at the common bulkhead or at the bottom COPV mount at the tank side wall. It could be cryro cycling or material dislocation. A failure in that area would cause RP-1/LOX mixing and the possible kinetic energy for ignition. It would an event that happens very fast...
You do realize the drawing your working from does not match reality in many ways... ;)
LOL... Believe me when I say... I tried very hard to find one online... ;D
So, I haven't had a chance to read every comment on the last 10 pages, but a friend of mine who worked Centaur for many years mentioned a theory I hadn't heard much in the first several dozen pages of this thread. His thought was that the failure could be due to a common bulkhead failure that wasn't driven by COPVs popping, but by something else such as ullage collapse. IIRC, someone mentioned somewhere that SpaceX was trying some new approaches for being able to give them longer hold-time with the subcooled propellants. It may be possible that something they did lead to ullage collapse in the S2 LOX tank (ie the cold GOX in the ullage is chilled enough by the subcooled LOX that it condenses, dropping the pressure enough to create a wrong-way pressure differential across the bulkhead. Because the vehicle is constrained pretty strongly at the top and bottom, the outer walls might have been prevented from buckling, but the bulkhead could have buckled or flipped. Localized mixing would've created a shock sensitive enough mixture that the dynamics of the event could have provided its own initiation energy.Still pretty interesting Jon, Thanks! :)
There's lots of possibilities how this could happen, but if it is the cause, it's not necessarily a rocket or a GSE/pad failure per se, but possibly an experiment gone horribly wrong. It would bode well for getting back to flight soon, but if true, may suggest that there are more risks to using highly subcooled propellants than initially thought.
Anyhow, figured I'd mention that one, since I think it's probably just as likely as a COPV/pressurization system related failure. And would fit in with the "not some stupid mistake SpaceX should've obviously not made, but something subtle about how they're pushing the envelope performance-wise".
~Jon
So, I haven't had a chance to read every comment on the last 10 pages, but a friend of mine who worked Centaur for many years mentioned a theory I hadn't heard much in the first several dozen pages of this thread. His thought was that the failure could be due to a common bulkhead failure that wasn't driven by COPVs popping, but by something else such as ullage collapse. IIRC, someone mentioned somewhere that SpaceX was trying some new approaches for being able to give them longer hold-time with the subcooled propellants. It may be possible that something they did lead to ullage collapse in the S2 LOX tank (ie the cold GOX in the ullage is chilled enough by the subcooled LOX that it condenses, dropping the pressure enough to create a wrong-way pressure differential across the bulkhead. Because the vehicle is constrained pretty strongly at the top and bottom, the outer walls might have been prevented from buckling, but the bulkhead could have buckled or flipped. Localized mixing would've created a shock sensitive enough mixture that the dynamics of the event could have provided its own initiation energy.
[SNIP]
~Jon
We must always bear in mind that it could be an unfortunate combination of design, materials, forces, events, conditions and not a smoking gun...
It may be possible that something they did lead to ullage collapse in the S2 LOX tank (ie the cold GOX in the ullage is chilled enough by the subcooled LOX that it condenses, dropping the pressure enough to create a wrong-way pressure differential across the bulkhead.
It may be possible that something they did lead to ullage collapse in the S2 LOX tank (ie the cold GOX in the ullage is chilled enough by the subcooled LOX that it condenses, dropping the pressure enough to create a wrong-way pressure differential across the bulkhead.
Pretty interesting theory, but could ullage collapse really happen that quickly that it wouldn't leave an obvious smoking gun in telemetry via a dropping pressure trend? I (naively) wouldn't think so.
How do we know if there hasn't been a smoking gun in the telemetry?
How do we know if there hasn't been a smoking gun in the telemetry?
Granted, we don't know, but the press statement talking about a few tens of milliseconds of telemetry to me sounds like the anomaly had a rather quick onset.
So, I haven't had a chance to read every comment on the last 10 pages, but a friend of mine who worked Centaur for many years mentioned a theory I hadn't heard much in the first several dozen pages of this thread. His thought was that the failure could be due to a common bulkhead failure that wasn't driven by COPVs popping, but by something else such as ullage collapse. IIRC, someone mentioned somewhere that SpaceX was trying some new approaches for being able to give them longer hold-time with the subcooled propellants. It may be possible that something they did lead to ullage collapse in the S2 LOX tank (ie the cold GOX in the ullage is chilled enough by the subcooled LOX that it condenses, dropping the pressure enough to create a wrong-way pressure differential across the bulkhead. Because the vehicle is constrained pretty strongly at the top and bottom, the outer walls might have been prevented from buckling, but the bulkhead could have buckled or flipped. Localized mixing would've created a shock sensitive enough mixture that the dynamics of the event could have provided its own initiation energy.
There's lots of possibilities how this could happen, but if it is the cause, it's not necessarily a rocket or a GSE/pad failure per se, but possibly an experiment gone horribly wrong. It would bode well for getting back to flight soon, but if true, may suggest that there are more risks to using highly subcooled propellants than initially thought.
Anyhow, figured I'd mention that one, since I think it's probably just as likely as a COPV/pressurization system related failure. And would fit in with the "not some stupid mistake SpaceX should've obviously not made, but something subtle about how they're pushing the envelope performance-wise".
~Jon
It may be possible that something they did lead to ullage collapse in the S2 LOX tank (ie the cold GOX in the ullage is chilled enough by the subcooled LOX that it condenses, dropping the pressure enough to create a wrong-way pressure differential across the bulkhead.
Here is a picture of the interior of a LOX tank (http://www.astronautinews.it/2015/07/26/un-supporto-difettoso-la-causa-della-perdita-del-falcon-9/) in the F9. Are the COPV those three black cylinders along the walls?
It may be more of a response to Tory Bruno's initial comments about 'not speculating about causes too soon' after the Orbital-6 anomaly. ¯\_(ツ)_/¯
Side note2, i notice that elon is tweeting less and shotwell wrote the official company response. Some people have interpreted this bearish for id-ing root cause(s). I wonder if since crs-7 was so recent I'd imagine they and their partners are confident in getting great resolution. So less tweeting more patience into working the problem. I do wonder how elon decides whether he's going to work on spx blow ups vs tsla issues. I'm guessing spx since this is revenue stopping at the moment.
I've read most of the comments in this thread....
Currently 2 plauseible scenarios stand out and both have their faults:
Scenario 1: COPV failure.
Goes like this:
1. COPV (carbon fiber on top of aluminium) fails for unknown reason (may be delamination, may be something else)
2. It is safe to say that when carbon fiber fails, it has tremendous energy stored in it (high tensile strength and stiffness combined). That makes us assume, that possibly helium COPV (at ~6000psi) fails like in (see Youtube video in previous post), and then carbon fiber and epoxy will be dispersed as a fine dust into LOX, thereby turning immediate vincinity of the helium bottle onto an Oxyliquit.
3. Supersonic compression wave follows, heating up the mixture of fine carbon and epoxy dust in LOX to a point of detonation
4. Detonation occurs throwing pieces of S2 into different directions
5. 60ms after that behind still burning fireball, the now open LOX tank disperses large cloud of vaporizing oxygen
6. At the same time pressure wave propagates down the LOX pressure vessel destroying common bulkhead
7. RP-1 flows down the scene and COPV submerged in RP-1 tank gets ripped from the tank breaking the tubing to pressure regulator
8. RP-1 tank's COPV gets propelled upwards by releasing helium from broken tubing
the rest is not worth describing.
Issues with this scenario:
1. Why didn't the back side or the whole circumference of S2 burst open due to sharp pressure wave
2. Why wasn't the payload lifted by pressure release into LOX
3. Why the epicenter of initial detonation SEEMS to be just at or outside the surface of S2
4. Why did the COPV fail in first place
...
However, having looked at this more I am starting to question the COPV failure idea as well. This event seems too energetic for that in terms of burning gases already being apparent as the stage is intially breaching. To me this says either fts related or somehow there was a sudden fast fire already inside the lox tank nano or mili seconds before it breached.
...
Well, if you look carefully, then I propose a way, how the detonation initiated inside the tank. See points marked in bold.
Wow. I did not realize Ariane 5 carried 168Kg of liquid Helium in the LOX tank.
Are you sure it's located in the LOX tank? It doesn't look that way to me.
Does anyone have an idea what data rate the 3000 channels of data were recording at? I would assume some channels video and some GSE equipment would be low ( 30 to 100 Hz).
Just trying to understand what kind of resolution Space X will see during the 30-35 miliseconds. Got to believe SpaceX has all the digital data reviewed by now and have a good idea as to the source of the problem if not the reason.
I would think SpaceX already has the data that illuminates what happened. However, you're right, there is proximate cause and then there is root cause.
The data likely has shown them what the proximate cause was -- what was happening that made the rocket go boom. As to what began the chain of events that led to the proximate cause, that's the item that will take longer to define. And that's what they need to get down to before they can even define their next steps in making the system safe to fly again.
The one thing I will say is this --it is not the exact same causation path that happened on CRS-7. This was a sudden, abrupt failure, while CRS-7's overpressurization event occurred over a period of up to 10 seconds. If this was an overpressurization event, it occurred far, far more rapidly. So, people who are sitting back and dispensing their disgust about how SpaceX failed to fix the same problem that took down CRS-7 should just stop, since it's impossible that this could be the same problem.
It could possibly be a different problem in the same system, but it's not the same problem, has a different proximate cause, and almost certainly has a different root cause.
It may be possible that something they did lead to ullage collapse in the S2 LOX tank (ie the cold GOX in the ullage is chilled enough by the subcooled LOX that it condenses, dropping the pressure enough to create a wrong-way pressure differential across the bulkhead.
Pretty interesting theory, but could ullage collapse really happen that quickly that it wouldn't leave an obvious smoking gun in telemetry via a dropping pressure trend? I (naively) wouldn't think so.
How do we know if there hasn't been a smoking gun in the telemetry? Even if SpaceX was reasonably sure they knew the problem, do you think they'd announce their findings before double and triple checking everything, and making sure the FAA, DoD, and NASA folks on their investigation panel were in agreement?
But yeah, while ullage collapse can happen quickly, it wouldn't be instantaneous, though it could be fairly quick.
~Jon
58.72%, to be precise
It is not only possible but almost 60% likely to have been a very similar problem with the same components.
Does anyone have an idea what data rate the 3000 channels of data were recording at? I would assume some channels video and some GSE equipment would be low ( 30 to 100 Hz).
Just trying to understand what kind of resolution Space X will see during the 30-35 miliseconds. Got to believe SpaceX has all the digital data reviewed by now and have a good idea as to the source of the problem if not the reason.
I would think SpaceX already has the data that illuminates what happened. However, you're right, there is proximate cause and then there is root cause.
The data likely has shown them what the proximate cause was -- what was happening that made the rocket go boom. As to what began the chain of events that led to the proximate cause, that's the item that will take longer to define. And that's what they need to get down to before they can even define their next steps in making the system safe to fly again.
The one thing I will say is this --it is not the exact same causation path that happened on CRS-7. This was a sudden, abrupt failure, while CRS-7's overpressurization event occurred over a period of up to 10 seconds. If this was an overpressurization event, it occurred far, far more rapidly. So, people who are sitting back and dispensing their disgust about how SpaceX failed to fix the same problem that took down CRS-7 should just stop, since it's impossible that this could be the same problem.
It could possibly be a different problem in the same system, but it's not the same problem, has a different proximate cause, and almost certainly has a different root cause.
It is not only possible but almost 60% likely to have been a very similar problem with the same components. Failure mode differs because helium gas lines failed first in crs7 resulting in a "slower" overpressure as compared to a supersonic shockwave generated by a burst COPV bottle.
Yeah, but you're using metric percents.58.72%, to be precise
It is not only possible but almost 60% likely to have been a very similar problem with the same components.
58.72%, to be precise
It is not only possible but almost 60% likely to have been a very similar problem with the same components.
A question: How long do the telemetry systems stay alive? Would spacex still get telemetry from sensors in the S1 while S2 is already gone? Would they still get data from the fairing and the payload while it hung on the strongback?That depends on the physical data path the cabling takes and where exactly the explosion originated. If it originated from the umbilical, and they had a data line in the umbilical, they would have lost all the signal, all at once. If there was an alternate path (say through the interstage) then they would probably see further into the event. If the telemetry transmitters were active, then the sensitive paths would be he path from the sensors to the transmitter and avionics hardware on top of the upper stage.
So, I haven't had a chance to read every comment on the last 10 pages, but a friend of mine who worked Centaur for many years mentioned a theory I hadn't heard much in the first several dozen pages of this thread. His thought was that the failure could be due to a common bulkhead failure that wasn't driven by COPVs popping, but by something else such as ullage collapse. IIRC, someone mentioned somewhere that SpaceX was trying some new approaches for being able to give them longer hold-time with the subcooled propellants. It may be possible that something they did lead to ullage collapse in the S2 LOX tank (ie the cold GOX in the ullage is chilled enough by the subcooled LOX that it condenses, dropping the pressure enough to create a wrong-way pressure differential across the bulkhead. Because the vehicle is constrained pretty strongly at the top and bottom, the outer walls might have been prevented from buckling, but the bulkhead could have buckled or flipped. Localized mixing would've created a shock sensitive enough mixture that the dynamics of the event could have provided its own initiation energy.
Looking at the video, this really doesn't look to be an internal explosion.
Maybe a burn off of the vented LOX, but not an internal blast. However; we can't be certain of this until we can get some video from another angle. An internal explosion would have lifted the payload clear of the tower as the upper stage unzipped and peeled away to the sides.
I base this on other pad explosions I've seen in previous videos, as well as aircraft explosions of a similar nature.
This looks like an uncontained explosion, that occurred from the tower or its near vicinity, that expanded into the side of the stage, rupturing it sideways, and then inhibiting the fuel and LOX. As an uncontained explosion, both the initial and the rupture ignition, there wouldn't have been enough upwards force to shift the payload upwards to any sufficient distance.
It should also be noted that such an internal explosion, would have forced the upper stage engine downwards to the first state's LOX tank, further adding fuel to the explosion, magnifying the over all explosive force helping to throw the payload at least several meters up and away from the tower.
About 50% of the time everyone on this site turns out to be wrong (me included)58.72%, to be precise
It is not only possible but almost 60% likely to have been a very similar problem with the same components.
78.26% of statistics are made up on the spot. And 68.23% of those statistics are then defended vigorously when questioned...
~Jon
I agree with you 114.28%
Despite appearances, this probably wasn't a "detonation." It was a "fast fire" as Elon said, and there is a world of difference. An internal pressure event followed by tank rupture and "fast fire" of LOX/RP-1 combustion appears consistent with what we saw.
This would require flipping bulkhead to lift against several meters worth of hydraulic pressure of LOX in LOX tank. Does not look likely to me. Also, if explosive mixture formed in the tanks (not outside of the tanks), the kaboom would be much more energetic, sending payload flying upwards.
Despite appearances, this probably wasn't a "detonation." It was a "fast fire" as Elon said, and there is a world of difference. An internal pressure event followed by tank rupture and "fast fire" of LOX/RP-1 combustion appears consistent with what we saw.
Where Frame 0 is pre-event (USLaunchReport video)
Where Frame 1 is post-event,
I agree with you on Frame 2 forward. However, not prior to Frame 2.
Frame 1 shows a "fast fire" moving at between 2,000 and 5,000 feet per second. In the world I live in, 2,000 to 5,000 feet per second is called a detonation.
After Frame 2, it slows to 100-200 feet per second, and that's a deflagration, at least in the world I live in.
I still beg to disagree with Elon... It was an over-pressure event of an initial detonation followed by deflagration. I'm sure those on this site that saw it and heard it live would agree. The distance that parts flew would confirm the energy required...A tank losing pressure suddenly is VERY energetic. Obviously there was fire almost immediately since we don't see the tank burst until after we see fire. But I believe an over-pressurized LOX tank could easily provide enough energy to explain the small flying parts we see early on. There was an incident in McGregor a couple years ago with nitrogen tanks exploding and it was called an explosion. As far as we know there was no fire involved and thus no detonation.
Does anyone have an idea what data rate the 3000 channels of data were recording at? I would assume some channels video and some GSE equipment would be low ( 30 to 100 Hz).
Just trying to understand what kind of resolution Space X will see during the 30-35 miliseconds. Got to believe SpaceX has all the digital data reviewed by now and have a good idea as to the source of the problem if not the reason.
I would think SpaceX already has the data that illuminates what happened. However, you're right, there is proximate cause and then there is root cause.
The data likely has shown them what the proximate cause was -- what was happening that made the rocket go boom. As to what began the chain of events that led to the proximate cause, that's the item that will take longer to define. And that's what they need to get down to before they can even define their next steps in making the system safe to fly again.
The one thing I will say is this --it is not the exact same causation path that happened on CRS-7. This was a sudden, abrupt failure, while CRS-7's overpressurization event occurred over a period of up to 10 seconds. If this was an overpressurization event, it occurred far, far more rapidly. So, people who are sitting back and dispensing their disgust about how SpaceX failed to fix the same problem that took down CRS-7 should just stop, since it's impossible that this could be the same problem.
It could possibly be a different problem in the same system, but it's not the same problem, has a different proximate cause, and almost certainly has a different root cause.
It is not only possible but almost 60% likely to have been a very similar problem with the same components. Failure mode differs because helium gas lines failed first in crs7 resulting in a "slower" overpressure as compared to a supersonic shockwave generated by a burst COPV bottle.
That's a lot more confident than I think we can be at this point. I think a COPV failure is one of the more likely failure sources, but far from the only credible cause of failure. I know this is hard for aerospace engineers, but humility is in order, especially with how little data we're working with here.
~Jon
Despite appearances, this probably wasn't a "detonation." It was a "fast fire" as Elon said, and there is a world of difference. An internal pressure event followed by tank rupture and "fast fire" of LOX/RP-1 combustion appears consistent with what we saw.
Where Frame 0 is pre-event (USLaunchReport video)
Where Frame 1 is post-event,
I agree with you on Frame 2 forward. However, not prior to Frame 2.
Frame 1 shows a "fast fire" moving at between 2,000 and 5,000 feet per second. In the world I live in, 2,000 to 5,000 feet per second is called a detonation.
After Frame 2, it slows to 100-200 feet per second, and that's a deflagration, at least in the world I live in.
But what people fail to realize is that a localized internal detonation need not have enough impulse to lift the fairing up against the probably heftily overbuilt strongback. If we're talking about a small pocket of mixed LOX/RP-1 right near the outer wall where the bulkhead attaches, you could see most of the energy going out the side wall.
~Jon
I'm speaking of parts being reported around outside the launch complex...I still beg to disagree with Elon... It was an over-pressure event of an initial detonation followed by deflagration. I'm sure those on this site that saw it and heard it live would agree. The distance that parts flew would confirm the energy required...A tank losing pressure suddenly is VERY energetic. Obviously there was fire almost immediately since we don't see the tank burst until after we see fire. But I believe an over-pressurized LOX tank could easily provide enough energy to explain the small flying parts we see early on. There was an incident in McGregor a couple years ago with nitrogen tanks exploding and it was called an explosion. As far as we know there was no fire involved and thus no detonation.
Detonation implies force applied by burning materials. In this case the force and the burning materials could be separate. Hopefully Elon knows more than us about the vehicle and the anomaly, so there is probably an explanation.
I still beg to disagree with Elon... It was an over-pressure event of an initial detonation followed by deflagration. I'm sure those on this site that saw it and heard it live would agree. The distance that parts flew would confirm the energy required...
Despite appearances, this probably wasn't a "detonation." It was a "fast fire" as Elon said, and there is a world of difference. An internal pressure event followed by tank rupture and "fast fire" of LOX/RP-1 combustion appears consistent with what we saw.
Where Frame 0 is pre-event (USLaunchReport video)
Where Frame 1 is post-event,
I agree with you on Frame 2 forward. However, not prior to Frame 2.
Frame 1 shows a "fast fire" moving at between 2,000 and 5,000 feet per second. In the world I live in, 2,000 to 5,000 feet per second is called a detonation.
After Frame 2, it slows to 100-200 feet per second, and that's a deflagration, at least in the world I live in.
But what people fail to realize is that a localized internal detonation need not have enough impulse to lift the fairing up against the probably heftily overbuilt strongback. If we're talking about a small pocket of mixed LOX/RP-1 right near the outer wall where the bulkhead attaches, you could see most of the energy going out the side wall.
~Jon
Please don't take this as a snark, but the term "fast-fire" is meaningless in the world of physics that I teach...I still beg to disagree with Elon... It was an over-pressure event of an initial detonation followed by deflagration. I'm sure those on this site that saw it and heard it live would agree. The distance that parts flew would confirm the energy required...
His "fast fire" was in reference to Dragon abort. It doesn't seem the initial detonation was big enough to have any effect on Dragon, just at it had no apparent effect on the payload, and the following "fast fire" which eventually resulted in the destruction of the payload, was slow enough for Dragon to abort away.
Detonation implies force applied by burning materials. In this case the force and the burning materials could be separate. Hopefully Elon knows more than us about the vehicle and the anomaly, so there is probably an explanation.
As am I. They were small, shoebox size pieces. It doesn't take much force if it is directed as in the case of a pressure explosion. The initial breach obviously covered a pretty small area since we see the initial explosion radiating in just one direction. It is the same principle behind canons and pressure cooker bombs. A little force allowed to build up and released all at once can have a lot of umph.I'm speaking of parts being reported around outside the launch complex...I still beg to disagree with Elon... It was an over-pressure event of an initial detonation followed by deflagration. I'm sure those on this site that saw it and heard it live would agree. The distance that parts flew would confirm the energy required...A tank losing pressure suddenly is VERY energetic. Obviously there was fire almost immediately since we don't see the tank burst until after we see fire. But I believe an over-pressurized LOX tank could easily provide enough energy to explain the small flying parts we see early on. There was an incident in McGregor a couple years ago with nitrogen tanks exploding and it was called an explosion. As far as we know there was no fire involved and thus no detonation.
Detonation implies force applied by burning materials. In this case the force and the burning materials could be separate. Hopefully Elon knows more than us about the vehicle and the anomaly, so there is probably an explanation.
His words, not mine. And almost certainly can be wholly replaced with the word "deflagration" without changing the intent or meaning of the tweet at all.Please don't take this as a snark, but the term "fast-fire" is meaningless in the world of physics that I teach...I still beg to disagree with Elon... It was an over-pressure event of an initial detonation followed by deflagration. I'm sure those on this site that saw it and heard it live would agree. The distance that parts flew would confirm the energy required...
His "fast fire" was in reference to Dragon abort. It doesn't seem the initial detonation was big enough to have any effect on Dragon, just at it had no apparent effect on the payload, and the following "fast fire" which eventually resulted in the destruction of the payload, was slow enough for Dragon to abort away.
Now for something completely different.
I was skimming parts of this book: https://books.google.com/books?id=H9XKBQAAQBAJ
Its focus is on reducing the risk of industrial accidents. There are several discussions about how to design HVAC and AC systems so they don't inadvertently detonate. One minor tidbit just to spark an AC debate, don't mix water and aluminum shavings in a closed space. You'll build up hydrogen gas...
The book has lots of other examples of what not to do...
Does anyone know much about how the tower AC system was configured?
Would they still get data from the fairing and the payload while it hung on the strongback?
Can you confirm that these aren't very low ballistic coefficient items (foils, wraps, insulation, etc) that floated away on that huge thermal plume? I'd strongly suspect that anything found at 39A was this type of debris. Nothing in the video suggests that there was heavy or large debris flying more than a few hundred feet.I'm speaking of parts being reported around outside the launch complex...I still beg to disagree with Elon... It was an over-pressure event of an initial detonation followed by deflagration. I'm sure those on this site that saw it and heard it live would agree. The distance that parts flew would confirm the energy required...A tank losing pressure suddenly is VERY energetic. Obviously there was fire almost immediately since we don't see the tank burst until after we see fire. But I believe an over-pressurized LOX tank could easily provide enough energy to explain the small flying parts we see early on. There was an incident in McGregor a couple years ago with nitrogen tanks exploding and it was called an explosion. As far as we know there was no fire involved and thus no detonation.
Detonation implies force applied by burning materials. In this case the force and the burning materials could be separate. Hopefully Elon knows more than us about the vehicle and the anomaly, so there is probably an explanation.
If there was an initial detonation (supersonic speed) then shouldn't we have seen a shock wave, especially in the humid coastal air.
Yes, I know it was "his words", hence the "no snark" comment towards you! ;)His words, not mine. And almost certainly can be wholly replaced with the word "deflagration" without changing the intent or meaning of the tweet at all.Please don't take this as a snark, but the term "fast-fire" is meaningless in the world of physics that I teach...I still beg to disagree with Elon... It was an over-pressure event of an initial detonation followed by deflagration. I'm sure those on this site that saw it and heard it live would agree. The distance that parts flew would confirm the energy required...
His "fast fire" was in reference to Dragon abort. It doesn't seem the initial detonation was big enough to have any effect on Dragon, just at it had no apparent effect on the payload, and the following "fast fire" which eventually resulted in the destruction of the payload, was slow enough for Dragon to abort away.
.
Does anyone know much about how the tower AC system was configured?
If there was an initial detonation (supersonic speed) then shouldn't we have seen a shock wave, especially in the humid coastal air.If you have multiple near simultaneous events Ron you will get wave interference and will be hard to discern without high speed cameras...
Despite appearances, this probably wasn't a "detonation." It was a "fast fire" as Elon said, and there is a world of difference. An internal pressure event followed by tank rupture and "fast fire" of LOX/RP-1 combustion appears consistent with what we saw.
Where Frame 0 is pre-event (USLaunchReport video)
Where Frame 1 is post-event,
I agree with you on Frame 2 forward. However, not prior to Frame 2.
Frame 1 shows a "fast fire" moving at between 2,000 and 5,000 feet per second. In the world I live in, 2,000 to 5,000 feet per second is called a detonation.
After Frame 2, it slows to 100-200 feet per second, and that's a deflagration, at least in the world I live in.
But what people fail to realize is that a localized internal detonation need not have enough impulse to lift the fairing up against the probably heftily overbuilt strongback. If we're talking about a small pocket of mixed LOX/RP-1 right near the outer wall where the bulkhead attaches, you could see most of the energy going out the side wall.
~Jon
Jon, would you care to speculate on how such a pocket would occur? Based on what we have seen so far, the pocket would be asymmetrical facing the camera (an exemplary example of Murphy in action if you ask me).
.
Does anyone know much about how the tower AC system was configured?
The system is located in a building west of the pad. And it would not be the source of any combustibles.
.
Does anyone know much about how the tower AC system was configured?
The system is located in a building west of the pad. And it would not be the source of any combustibles.
Jim, you're some kind of wonderful. :) You're the only person I've ever known who can blow up one of my ideas in 21 words or less. :)
Despite appearances, this probably wasn't a "detonation." It was a "fast fire" as Elon said, and there is a world of difference. An internal pressure event followed by tank rupture and "fast fire" of LOX/RP-1 combustion appears consistent with what we saw.
Where Frame 0 is pre-event (USLaunchReport video)
Where Frame 1 is post-event,
I agree with you on Frame 2 forward. However, not prior to Frame 2.
Frame 1 shows a "fast fire" moving at between 2,000 and 5,000 feet per second. In the world I live in, 2,000 to 5,000 feet per second is called a detonation.
After Frame 2, it slows to 100-200 feet per second, and that's a deflagration, at least in the world I live in.
But what people fail to realize is that a localized internal detonation need not have enough impulse to lift the fairing up against the probably heftily overbuilt strongback. If we're talking about a small pocket of mixed LOX/RP-1 right near the outer wall where the bulkhead attaches, you could see most of the energy going out the side wall.
~Jon
Jon, would you care to speculate on how such a pocket would occur? Based on what we have seen so far, the pocket would be asymmetrical facing the camera (an exemplary example of Murphy in action if you ask me).
Some sort of localized structural failure of the common bulkhead, driven by one of the mechanisms under discussion (CB inversion driven by ullage collapse or some other mechanism, COPV failure, pressurization system failure, etc). A CB failure doesn't mean you get instantaneous mixing of all the LOX and RP-1, especially if the failure is fairly small.
Handwaving here, I just think the "if it was an internal explosion, it would have to be a big one that would pop the payload off" crowd is overstating their case.
~Jon
If there was an initial detonation (supersonic speed) then shouldn't we have seen a shock wave, especially in the humid coastal air.
However, I did take a brief look at the venting oxygen clouds on S1, and you can see that they move down as if in response to a shock wave. That's suggestive, but not definitive.
I'm still looking at at brittle fracture of material of either the FSW at the common bulkhead or at the bottom COPV mount at the tank side wall. It could be cryro cycling or material dislocation. A failure in that area would cause RP-1/LOX mixing and the possible kinetic energy for ignition. It would an event that happens very fast...
Hmm, the bottom of that COPV mount you have circled in red does appear to be around the approximate centroid of the flash seen in the video.
I have no pet theory here, as amusing as it is to watch people with random backgrounds try to correct Jim and nitpick to support their own. That said, I do wonder - personally - if the root cause of this might come down a handling mishap with S2 somewhere along the way days, weeks or even months ago, such as a jarred or dropped tank in the factory (say a jolt of 2" - 3" in placing on the cradle for transport or assembly jig, or the over-the-road transport truck having a minor collision along the route such as bumping a concrete post at a truck stop, running over a curb making a turn, etc)? Alternately, perhaps a bit of manufacturing re-work might have been required during assembly at one of the COPV mounts which was performed in a defective manner (something like that brought down an entire 747 full of people in Japan once) ... In other words, a seemingly minor event somewhere along the that seemed of no consequence but which eventually resulted in a major mishap.
It may be interesting to note that at T-8:00 the MVAC hydraulics are pressurized and prepared for bleed. You can hear the call out on at least the last three technical streams. This is the only call out in regards to the second stage around this time, and according to the official statement the anomaly was about eight minutes before the engines would have fired. Since the MVAC uses RP-1 as hydraulic fluid, could this have been a leak somewhere in the hydraulic system?Welcome to the forum! :)
Detonation implies force applied by burning materials. In this case the force and the burning materials could be separate. Hopefully Elon knows more than us about the vehicle and the anomaly, so there is probably an explanation.
Here's my definition of detonation.
The event expansion rate moves faster than the local speed of sound.
Here's my definition of deflagration.
The event expansion rate moves slower than the local speed of sound.
Per my definition, Frame one is detonation.
Per my definition, after Frame one is deflagration.
Were the tanks not at flight pressure with helium? How could that support combustion without liquid prop mixing, become vapor and then ignite? I'm trying to understand what you are saying...
Detonation implies force applied by burning materials. In this case the force and the burning materials could be separate. Hopefully Elon knows more than us about the vehicle and the anomaly, so there is probably an explanation.
Here's my definition of detonation.
The event expansion rate moves faster than the local speed of sound.
Here's my definition of deflagration.
The event expansion rate moves slower than the local speed of sound.
Per my definition, Frame one is detonation.
Per my definition, after Frame one is deflagration.
A simple overpressure inside the tank, with no combustion, that causes the tank to rupture will produce a supersonic shock wave. No detonation required for that. A bursting balloon will be a "detonation" by your definition.
So a "fast fire" combustion event that is initially contained inside the tank, which then ruptures, will produce a supersonic expansion of flaming combustion products, ie what we see in the first few frames.
Again, this is entirely consistent with a "fast fire" combustion inside the tank, which ruptures the tank and causes supersonic expansion of the hot gases. The "fast fire" then continues outside the tank as more LOX/RP-1 combust.
No detonation needed to explain what we saw, and I doubt we saw one. Overpressure and/or "fast fire" that begins inside the tank and ruptures it would produce what we saw and is easier to initiate than a detonation.
Were the tanks not at flight pressure with helium? How could that support combustion without liquid prop mixing and then ignite? I'm trying to understand what you are saying...
Oh, I agree with terminology use but you have me curious for the mechanism for a "fast-fire" in a single tank under flight pressure helium...QuoteWere the tanks not at flight pressure with helium? How could that support combustion without liquid prop mixing and then ignite? I'm trying to understand what you are saying...
What I'm saying is that LOX and RP-1 combusting is not necessarily a "detonation." It can be a "deflagration," or fast fire. There is a difference. People seem to be throwing around the word "detonation" without fully understanding what it actually means.
Oh, I agree with terminology use but you have me curious for the mechanism for a "fast-fire" in a single tank under flight pressure helium...QuoteWere the tanks not at flight pressure with helium? How could that support combustion without liquid prop mixing and then ignite? I'm trying to understand what you are saying...
What I'm saying is that LOX and RP-1 combusting is not necessarily a "detonation." It can be a "deflagration," or fast fire. There is a difference. People seem to be throwing around the word "detonation" without fully understanding what it actually means.
The problem with "words" that they generate imagery that can be unique for each individual and why in physics we stick to numbers...Oh, I agree with terminology use but you have me curious for the mechanism for a "fast-fire" in a single tank under flight pressure helium...QuoteWere the tanks not at flight pressure with helium? How could that support combustion without liquid prop mixing and then ignite? I'm trying to understand what you are saying...
What I'm saying is that LOX and RP-1 combusting is not necessarily a "detonation." It can be a "deflagration," or fast fire. There is a difference. People seem to be throwing around the word "detonation" without fully understanding what it actually means.
I don't know what happened inside. Maybe a bulkhead leak/burst under a too-high pressure differential. Then internal "deflagration" followed by stage rupture. Or a COPV burst provided enough energy to intiate combustion of LOX with the overwrap material.
All I'm saying is that an internal "deflagration" could have caused what we saw in the video. It was not necessarily a "detonation" as was asserted upthread.
As a propulsion engineer I worked with solid propellants that could "deflagrate" (burn fast) and/or "detonate," and there is a technical difference, with a continuum between them, depending on how fast the deflagration proceeds. This is true also of the liquid-phase reactants involved here.
In "explosions" like this, people may assume that high-speed combustion/explosion events must be the result of "detonation," and my example of the hydogen/oxygen balloon bursting shows that this is not necessarily true.
The problem with "words" that they generate imagery specific for each individual and why in physics we stick to numbers...
Oh, I agree with terminology use but you have me curious for the mechanism for a "fast-fire" in a single tank under flight pressure helium...QuoteWere the tanks not at flight pressure with helium? How could that support combustion without liquid prop mixing and then ignite? I'm trying to understand what you are saying...
What I'm saying is that LOX and RP-1 combusting is not necessarily a "detonation." It can be a "deflagration," or fast fire. There is a difference. People seem to be throwing around the word "detonation" without fully understanding what it actually means.
Oh, I agree with terminology use but you have me curious for the mechanism for a "fast-fire" in a single tank under flight pressure helium...QuoteWere the tanks not at flight pressure with helium? How could that support combustion without liquid prop mixing and then ignite? I'm trying to understand what you are saying...
What I'm saying is that LOX and RP-1 combusting is not necessarily a "detonation." It can be a "deflagration," or fast fire. There is a difference. People seem to be throwing around the word "detonation" without fully understanding what it actually means.
I don't know what happened inside. Maybe a bulkhead leak/burst under a too-high pressure differential. Then internal "deflagration" followed by stage rupture. Or a COPV burst provided enough energy to intiate combustion of LOX with the overwrap material.
All I'm saying is that an internal "deflagration" could have caused what we saw in the video. It was not necessarily a "detonation" as was asserted upthread.
As a propulsion engineer I worked with solid propellants that could "deflagrate" (burn fast) and/or "detonate," and there is a technical difference, with a continuum between them, depending on how fast the deflagration proceeds. This is true also of the liquid-phase reactants involved here.
Seeing/hearing an event like this, observers may assume the event was the result of a "detonation," and my earlier example of the hydogen/oxygen balloon bursting shows that this is not necessarily true.
QuoteThe problem with "words" that they generate imagery specific for each individual and why in physics we stick to numbers...
And engineers working with energetic materials like propellants also have very specific definitions for words like "deflagration," "detonation," etc. Unfortunately, not all armchair rocket scientists have a firm grasp on those definitions.
I'll take that one step further for each engineering discipline. For example; a combustion engineer in the automotive field, detonation would mean a specific event that what happening within the combustion chamber without a timed ignition spark...QuoteThe problem with "words" that they generate imagery specific for each individual and why in physics we stick to numbers...
And engineers working with energetic materials like propellants also have very specific definitions for words like "deflagration," "detonation," etc. Unfortunately, not all armchair rocket scientists have a firm grasp on those definitions.
Oh, I agree with terminology use but you have me curious for the mechanism for a "fast-fire" in a single tank under flight pressure helium...QuoteWere the tanks not at flight pressure with helium? How could that support combustion without liquid prop mixing and then ignite? I'm trying to understand what you are saying...
What I'm saying is that LOX and RP-1 combusting is not necessarily a "detonation." It can be a "deflagration," or fast fire. There is a difference. People seem to be throwing around the word "detonation" without fully understanding what it actually means.
I don't know what happened inside. Maybe a bulkhead leak/burst under a too-high pressure differential. Then internal "deflagration" followed by stage rupture. Or a COPV burst provided enough energy to intiate combustion of LOX with the overwrap material.
All I'm saying is that an internal "deflagration" could have caused what we saw in the video. It was not necessarily a "detonation" as was asserted upthread.
As a propulsion engineer I worked with solid propellants that could "deflagrate" (burn fast) and/or "detonate," and there is a technical difference, with a continuum between them, depending on how fast the deflagration proceeds. This is true also of the liquid-phase reactants involved here.
Seeing/hearing an event like this, observers may assume the event was the result of a "detonation," and my earlier example of the hydogen/oxygen balloon bursting shows that this is not necessarily true.
My problem with internal deflagration is that the first visible signs would not be that flash followed by a decrease in magnitude..l
Then for a few frames it brightens up, diminishes, and then a secondary cloud of fluid appears, and everything catches fire and melts down.
Do we have an exact point in the sequence yet? I haven't heard/read anything yet unless I missed it...Oh, I agree with terminology use but you have me curious for the mechanism for a "fast-fire" in a single tank under flight pressure helium...QuoteWere the tanks not at flight pressure with helium? How could that support combustion without liquid prop mixing and then ignite? I'm trying to understand what you are saying...
What I'm saying is that LOX and RP-1 combusting is not necessarily a "detonation." It can be a "deflagration," or fast fire. There is a difference. People seem to be throwing around the word "detonation" without fully understanding what it actually means.
The tanks are not at flight pressure during prop loading, which is when the klabooma happened.
My problem with internal deflagration is that the first visible signs would not be that flash followed by a decrease in magnitude - it would be an ever-increasing thing, as more propellant and oxidizer got in contact.
Somehow, within one frame (say 30 mSec if it happened right after the previous frame), we went from nothing to a bright structure about, what, 6 m tall? Not quite supersonic in the "worst" case, but at least very close to it, and supersonic if it only took half a frame's time.
Then for a few frames it brightens up, diminishes, and then a secondary cloud of fluid appears, and everything catches fire and melts down.
So without speculating on what preceded the first external sign of trouble, my interpretation of what I see is a limited external explosion causing a shockwave, structural failure (maybe aided by a weakening caused by the root failure), and then the pressurized contents disperse and we have the big fire.
Faster video may tell a different tale of course. Lots could have happened within those 30 mSec.
Yes, an internal deflagration with a limited amount of fuel (say, COPV overwrap or some RP-1 from a bulkhead leak) combusting with LOX would produce exactly this phenomenon. The tank bursts suddenly with a bright flash and supersonic expansion, then the fireball grows more slowly and dims as the initial combustion products are consumed.QuoteThen for a few frames it brightens up, diminishes, and then a secondary cloud of fluid appears, and everything catches fire and melts down.
Don't know why it brightens up again, maybe more fuel is becoming vaporized/atomized and available for combustion. But again, this isn't necessarily detonation. It's about how much fuel and oxidizer is in contact at any time in the event.
Correct timeline (http://spaceflight101.com/falcon-9-ft-countdown-timeline/):
Falcon 9 FT – Countdown Timeline
All Times Approximate.
Time Event
L-15:00:00 Falcon 9 to Vertical
L-10:00:00 Countdown Initiation, Launch Vehicle Power-Up
L-6:00:00 First Weather Balloon Release
L-5:00:00 Launch Area Evacuation
L-4:45:00 Range Controllers on Station
L-4:35:00 Falcon 9 Attitude Control System N2 Loading
L-5:00:00 Launch Area Evacuation
L-2:45:00 Falcon 9 RF & Telemetry Checks
L-2:30:00 Falcon 9 Launch Vehicle Release System Test
L-2:25:00 TEA-TEB Bleed In
L-1:45:00 Comm & FTS Checks
L-1:40:00 Data Flow Tests with Downrange Tracking Stations
L-1:00:00 Weather Briefing
L-0:50:00 RF Link Checks
L-0:45:00 Pre-Load Hold Point, Propellant Polls
L-0:45:00 Blast Danger Area Clear, Roadblocks Established
L-0:45:00 Flight Control System Setup (Flight Software Loading)
L-0:45:00 Final Tank Chill-In
L-0:40:00 Ready for Prop Load
L-0:38:00 Launch Readiness Poll
L-0:36:00 Tanks vented for Prop Loading
T-0:35:00 Automated Countdown Sequence, Master Script Running
T-0:34:45 Launch Enable to Flight Mode
T-0:34:30 RP-1 Flow to both Stages
T-0:33:30 Stage 1 Liquid Oxygen Loading
T-0:32:30 Confirm nominal Fuel Flow Rates
T-0:32:00 Latest Prop Flow Start
T-0:29:30 Stage 1 Helium Load
T-0:27:00 Spacecraft to Internal Power
T-0:25:30 Fuel Collector Pre-Valves Closed
T-0:25:00 All three Liquid Helium Pumps active
T-0:22:00 Stage 2 Fuel Loading Complete
T-0:19:30 Stage 2 Liquid Oxygen Loading
T-0:17:20 Stage 1 LOX Flowrate Adjustment for Stage 2 Fast Fill
T-0:13:15 Stage 2 Helium Loading
T-0:13:00 Stage 2 LOX Flow Adjustment for Helium Cryo Load
T-0:13:00 Countdown Recycle Point
T-0:12:45 Merlin 1D & MVac BTV Activation
T-0:10:15 Grid Fin Pneumatics Secured
T-0:10:05 Boostback Hazards Disabled
T-0:10:00 Stage 2 Venting for LOX Fast Fill
T-0:09:50 Flight Software Final Setups complete
T-0:09:45 TEA-TEB Ignition System Setup
T-0:09:45 Stage 2 Transmitter Re-Activation
T-0:09:30 M1D Trim Valve Cycling
T-0:09:15 Stage 1 Helium Topping
T-0:07:45 MVac Fuel Trim Valve Setup
T-0:07:30 Engine Chill Readiness
T-0:07:00 Engine Chilldown (Bleed Valves Open, both Stages
T-0:07:00 Spacecraft on Internal Power
T-0:06:45 Stage 2 Helium Transition to Pipeline
T-0:06:35 MVac Hydraulics at Bleed Pressure
T-0:06:05 M1D Engines to TVC-Null Position
T-0:05:20 Flight Computers in Self-Alignment
T-0:05:20 Stage 1 Fuel Loading Complete
T-0:05:15 Launch Vehicle Heater Deactivation
T-0:05:00 Falcon 9 to Internal Power
T-0:05:00 Range Control Comm Check
T-0:05:00 Second Stage Nitrogen Loading Termination
T-0:04:50 Pressurization for Strongback Retract
T-0:04:40 Stage 2 TVC Bleed
T-0:04:30 Stage 2 RP-1 Bleed
T-0:04:30 Stage 2 Thrust Vector Control Test
T-0:04:20 Verify Good Self-Alignment
T-0:04:10 Strongback Cradles Opening
T-0:04:00 Vehicle Release Auto Sequence
T-0:03:40 TEA-TEB Ignition System Auto Sequence
T-0:03:30 Strongback Retraction
T-0:03:25 Flight Termination System to Internal Power
T-0:03:15 FTS on Internal
T-0:03:05 Flight Termination System Armed, FTS Ready for Launch
T-0:02:55 Verify Good Mvac TVC
T-0:02:45 Fuel Trim Valve to Flight Position
T-0:02:40 Stage 1 LOX at Flight Level
T-0:02:40 FTS Countdown Sequence
T-0:02:35 Strongback Retraction Complete
T-0:02:05 Stage 2 LOX at Flight Level
T-0:02:00 Falcon 9 Transfer to Internal Power Complete
T-0:01:35 Flight Control to Self Alignment
T-0:01:30 Launch Director: Go for Launch
T-0:01:30 Final Engine Chilldown
T-0:01:25 Helium Loading Termination
T-0:01:20 Engine Purge
T-0:01:00 Flight Computer to start-up
T-0:00:50 Stage 1, Stage 2 Pressurization for Flight
T-0:00:50 First Stage Thrust Vector Actuator Test
T-0:00:30 HOLD Call for Abort
T-0:00:20 All Tanks at Flight Pressure
T-0:00:15 Arm Pyrotechnics
T-0:00:10 Latest VC Abort
T-0:00:07 Pad Deck Water Deluge System Activation
T-0:00:03 Merlin Engine Ignition
T-0:00:00 LIFTOFF
Yes, an internal deflagration with a limited amount of fuel (say, COPV overwrap or some RP-1 from a bulkhead leak) combusting with LOX would produce exactly this phenomenon. The tank bursts suddenly with a bright flash and supersonic expansion, then the fireball grows more slowly and dims as the initial combustion products are consumed.QuoteThen for a few frames it brightens up, diminishes, and then a secondary cloud of fluid appears, and everything catches fire and melts down.
Don't know why it brightens up again, maybe more fuel is becoming vaporized/atomized and available for combustion. But again, this isn't necessarily detonation. It's about how much fuel and oxidizer is in contact at any time in the event.
If there is already combustion going on, then as the outer tank fails due to the rising pressure, (all within 30 ms) the liquid inside would be forced out and burn without the first fire going out.
And, IMO, there would be very little structure standing, and lots of debris.
But if the internal event was cold, and still resulted in a limited release of combustibles, and they ignited outside... then we're talking.
(Acknowledging that this kind of hand waved prediction is of low confidence... It's just playing with what little we've got to go on)
Flight press starts at T-0:00:50 and tanks don't reach flight press until T-0:00:20My question is still "where" were we on the sequence when the event happened?Correct timeline (http://spaceflight101.com/falcon-9-ft-countdown-timeline/):
Falcon 9 FT – Countdown Timeline
All Times Approximate.
Time Event
L-15:00:00 Falcon 9 to Vertical
L-10:00:00 Countdown Initiation, Launch Vehicle Power-Up
L-6:00:00 First Weather Balloon Release
L-5:00:00 Launch Area Evacuation
L-4:45:00 Range Controllers on Station
L-4:35:00 Falcon 9 Attitude Control System N2 Loading
L-5:00:00 Launch Area Evacuation
L-2:45:00 Falcon 9 RF & Telemetry Checks
L-2:30:00 Falcon 9 Launch Vehicle Release System Test
L-2:25:00 TEA-TEB Bleed In
L-1:45:00 Comm & FTS Checks
L-1:40:00 Data Flow Tests with Downrange Tracking Stations
L-1:00:00 Weather Briefing
L-0:50:00 RF Link Checks
L-0:45:00 Pre-Load Hold Point, Propellant Polls
L-0:45:00 Blast Danger Area Clear, Roadblocks Established
L-0:45:00 Flight Control System Setup (Flight Software Loading)
L-0:45:00 Final Tank Chill-In
L-0:40:00 Ready for Prop Load
L-0:38:00 Launch Readiness Poll
L-0:36:00 Tanks vented for Prop Loading
T-0:35:00 Automated Countdown Sequence, Master Script Running
T-0:34:45 Launch Enable to Flight Mode
T-0:34:30 RP-1 Flow to both Stages
T-0:33:30 Stage 1 Liquid Oxygen Loading
T-0:32:30 Confirm nominal Fuel Flow Rates
T-0:32:00 Latest Prop Flow Start
T-0:29:30 Stage 1 Helium Load
T-0:27:00 Spacecraft to Internal Power
T-0:25:30 Fuel Collector Pre-Valves Closed
T-0:25:00 All three Liquid Helium Pumps active
T-0:22:00 Stage 2 Fuel Loading Complete
T-0:19:30 Stage 2 Liquid Oxygen Loading
T-0:17:20 Stage 1 LOX Flowrate Adjustment for Stage 2 Fast Fill
T-0:13:15 Stage 2 Helium Loading
T-0:13:00 Stage 2 LOX Flow Adjustment for Helium Cryo Load
T-0:13:00 Countdown Recycle Point
T-0:12:45 Merlin 1D & MVac BTV Activation
T-0:10:15 Grid Fin Pneumatics Secured
T-0:10:05 Boostback Hazards Disabled
T-0:10:00 Stage 2 Venting for LOX Fast Fill
T-0:09:50 Flight Software Final Setups complete
T-0:09:45 TEA-TEB Ignition System Setup
T-0:09:45 Stage 2 Transmitter Re-Activation
T-0:09:30 M1D Trim Valve Cycling
T-0:09:15 Stage 1 Helium Topping
T-0:07:45 MVac Fuel Trim Valve Setup
T-0:07:30 Engine Chill Readiness
T-0:07:00 Engine Chilldown (Bleed Valves Open, both Stages
T-0:07:00 Spacecraft on Internal Power
T-0:06:45 Stage 2 Helium Transition to Pipeline
T-0:06:35 MVac Hydraulics at Bleed Pressure
T-0:06:05 M1D Engines to TVC-Null Position
T-0:05:20 Flight Computers in Self-Alignment
T-0:05:20 Stage 1 Fuel Loading Complete
T-0:05:15 Launch Vehicle Heater Deactivation
T-0:05:00 Falcon 9 to Internal Power
T-0:05:00 Range Control Comm Check
T-0:05:00 Second Stage Nitrogen Loading Termination
T-0:04:50 Pressurization for Strongback Retract
T-0:04:40 Stage 2 TVC Bleed
T-0:04:30 Stage 2 RP-1 Bleed
T-0:04:30 Stage 2 Thrust Vector Control Test
T-0:04:20 Verify Good Self-Alignment
T-0:04:10 Strongback Cradles Opening
T-0:04:00 Vehicle Release Auto Sequence
T-0:03:40 TEA-TEB Ignition System Auto Sequence
T-0:03:30 Strongback Retraction
T-0:03:25 Flight Termination System to Internal Power
T-0:03:15 FTS on Internal
T-0:03:05 Flight Termination System Armed, FTS Ready for Launch
T-0:02:55 Verify Good Mvac TVC
T-0:02:45 Fuel Trim Valve to Flight Position
T-0:02:40 Stage 1 LOX at Flight Level
T-0:02:40 FTS Countdown Sequence
T-0:02:35 Strongback Retraction Complete
T-0:02:05 Stage 2 LOX at Flight Level
T-0:02:00 Falcon 9 Transfer to Internal Power Complete
T-0:01:35 Flight Control to Self Alignment
T-0:01:30 Launch Director: Go for Launch
T-0:01:30 Final Engine Chilldown
T-0:01:25 Helium Loading Termination
T-0:01:20 Engine Purge
T-0:01:00 Flight Computer to start-up
T-0:00:50 Stage 1, Stage 2 Pressurization for Flight
T-0:00:50 First Stage Thrust Vector Actuator Test
T-0:00:30 HOLD Call for Abort
T-0:00:20 All Tanks at Flight Pressure
T-0:00:15 Arm Pyrotechnics
T-0:00:10 Latest VC Abort
T-0:00:07 Pad Deck Water Deluge System Activation
T-0:00:03 Merlin Engine Ignition
T-0:00:00 LIFTOFF
anomaly took place about eight minutes in advance of a scheduled test firing of a Falcon 9 rocket.
Correct timeline (http://spaceflight101.com/falcon-9-ft-countdown-timeline/):[/quote]
Falcon 9 FT – Countdown Timeline
...
T-0:34:30 RP-1 Flow to both Stages
T-0:33:30 Stage 1 Liquid Oxygen Loading
...
T-0:29:30 Stage 1 Helium Load
...
T-0:25:00 All three Liquid Helium Pumps active
T-0:22:00 Stage 2 Fuel Loading Complete
T-0:19:30 Stage 2 Liquid Oxygen Loading
T-0:17:20 Stage 1 LOX Flowrate Adjustment for Stage 2 Fast Fill
T-0:13:15 Stage 2 Helium Loading
T-0:13:00 Stage 2 LOX Flow Adjustment for Helium Cryo Load
...
T-0:10:00 Stage 2 Venting for LOX Fast Fill
...
T-0:09:15 Stage 1 Helium Topping
...
T-0:06:45 Stage 2 Helium Transition to Pipeline
...
T-0:02:40 Stage 1 LOX at Flight Level
...
T-0:02:05 Stage 2 LOX at Flight Level
...
T-0:01:25 Helium Loading Termination
...
T-0:00:50 Stage 1, Stage 2 Pressurization for Flight
...
T-0:00:20 All Tanks at Flight Pressure
T-0:00:15 Arm Pyrotechnics
...
The SpaceX statement said around T-8 minutes, so somewhere between Stage 1 Helium Topping and MVac Fuel Trim Valve Setup. I don't think that tells us anything useful since those things seem innocuous and there is a pretty big gap between those events. It does tell us that both LOX tanks were loading at the time and the RP-1 tank in the second stage was full.Flight press starts at T-0:00:50 and tanks don't reach flight press until T-0:00:20My question is still "where" were we on the sequence when the event happened?Correct timeline (http://spaceflight101.com/falcon-9-ft-countdown-timeline/):
Falcon 9 FT – Countdown Timeline
All Times Approximate.
Time Event
L-15:00:00 Falcon 9 to Vertical
L-10:00:00 Countdown Initiation, Launch Vehicle Power-Up
L-6:00:00 First Weather Balloon Release
L-5:00:00 Launch Area Evacuation
L-4:45:00 Range Controllers on Station
L-4:35:00 Falcon 9 Attitude Control System N2 Loading
L-5:00:00 Launch Area Evacuation
L-2:45:00 Falcon 9 RF & Telemetry Checks
L-2:30:00 Falcon 9 Launch Vehicle Release System Test
L-2:25:00 TEA-TEB Bleed In
L-1:45:00 Comm & FTS Checks
L-1:40:00 Data Flow Tests with Downrange Tracking Stations
L-1:00:00 Weather Briefing
L-0:50:00 RF Link Checks
L-0:45:00 Pre-Load Hold Point, Propellant Polls
L-0:45:00 Blast Danger Area Clear, Roadblocks Established
L-0:45:00 Flight Control System Setup (Flight Software Loading)
L-0:45:00 Final Tank Chill-In
L-0:40:00 Ready for Prop Load
L-0:38:00 Launch Readiness Poll
L-0:36:00 Tanks vented for Prop Loading
T-0:35:00 Automated Countdown Sequence, Master Script Running
T-0:34:45 Launch Enable to Flight Mode
T-0:34:30 RP-1 Flow to both Stages
T-0:33:30 Stage 1 Liquid Oxygen Loading
T-0:32:30 Confirm nominal Fuel Flow Rates
T-0:32:00 Latest Prop Flow Start
T-0:29:30 Stage 1 Helium Load
T-0:27:00 Spacecraft to Internal Power
T-0:25:30 Fuel Collector Pre-Valves Closed
T-0:25:00 All three Liquid Helium Pumps active
T-0:22:00 Stage 2 Fuel Loading Complete
T-0:19:30 Stage 2 Liquid Oxygen Loading
T-0:17:20 Stage 1 LOX Flowrate Adjustment for Stage 2 Fast Fill
T-0:13:15 Stage 2 Helium Loading
T-0:13:00 Stage 2 LOX Flow Adjustment for Helium Cryo Load
T-0:13:00 Countdown Recycle Point
T-0:12:45 Merlin 1D & MVac BTV Activation
T-0:10:15 Grid Fin Pneumatics Secured
T-0:10:05 Boostback Hazards Disabled
T-0:10:00 Stage 2 Venting for LOX Fast Fill
T-0:09:50 Flight Software Final Setups complete
T-0:09:45 TEA-TEB Ignition System Setup
T-0:09:45 Stage 2 Transmitter Re-Activation
T-0:09:30 M1D Trim Valve Cycling
T-0:09:15 Stage 1 Helium Topping
T-0:07:45 MVac Fuel Trim Valve Setup
T-0:07:30 Engine Chill Readiness
T-0:07:00 Engine Chilldown (Bleed Valves Open, both Stages
T-0:07:00 Spacecraft on Internal Power
T-0:06:45 Stage 2 Helium Transition to Pipeline
T-0:06:35 MVac Hydraulics at Bleed Pressure
T-0:06:05 M1D Engines to TVC-Null Position
T-0:05:20 Flight Computers in Self-Alignment
T-0:05:20 Stage 1 Fuel Loading Complete
T-0:05:15 Launch Vehicle Heater Deactivation
T-0:05:00 Falcon 9 to Internal Power
T-0:05:00 Range Control Comm Check
T-0:05:00 Second Stage Nitrogen Loading Termination
T-0:04:50 Pressurization for Strongback Retract
T-0:04:40 Stage 2 TVC Bleed
T-0:04:30 Stage 2 RP-1 Bleed
T-0:04:30 Stage 2 Thrust Vector Control Test
T-0:04:20 Verify Good Self-Alignment
T-0:04:10 Strongback Cradles Opening
T-0:04:00 Vehicle Release Auto Sequence
T-0:03:40 TEA-TEB Ignition System Auto Sequence
T-0:03:30 Strongback Retraction
T-0:03:25 Flight Termination System to Internal Power
T-0:03:15 FTS on Internal
T-0:03:05 Flight Termination System Armed, FTS Ready for Launch
T-0:02:55 Verify Good Mvac TVC
T-0:02:45 Fuel Trim Valve to Flight Position
T-0:02:40 Stage 1 LOX at Flight Level
T-0:02:40 FTS Countdown Sequence
T-0:02:35 Strongback Retraction Complete
T-0:02:05 Stage 2 LOX at Flight Level
T-0:02:00 Falcon 9 Transfer to Internal Power Complete
T-0:01:35 Flight Control to Self Alignment
T-0:01:30 Launch Director: Go for Launch
T-0:01:30 Final Engine Chilldown
T-0:01:25 Helium Loading Termination
T-0:01:20 Engine Purge
T-0:01:00 Flight Computer to start-up
T-0:00:50 Stage 1, Stage 2 Pressurization for Flight
T-0:00:50 First Stage Thrust Vector Actuator Test
T-0:00:30 HOLD Call for Abort
T-0:00:20 All Tanks at Flight Pressure
T-0:00:15 Arm Pyrotechnics
T-0:00:10 Latest VC Abort
T-0:00:07 Pad Deck Water Deluge System Activation
T-0:00:03 Merlin Engine Ignition
T-0:00:00 LIFTOFF
What is the tank pressure while loading? Doesn't it have to have some pressure to prevent the loaded tank from collapsing?
John
Jim, don't they do a nitrogen purge?What is the tank pressure while loading? Doesn't it have to have some pressure to prevent the loaded tank from collapsing?
John
No, the vehicle is structurally stable without pressure
What is the tank pressure while loading? Doesn't it have to have some pressure to prevent the loaded tank from collapsing?
John
No, the vehicle is structurally stable without pressure
The SpaceX statement said around T-8 minutes, so somewhere between Stage 1 Helium Topping and MVac Fuel Trim Valve Setup. I don't think that tells us anything useful since those things seem innocuous and there is a pretty big gap between those events. It does tell us that both LOX tanks were loading at the time and the RP-1 tank in the second stage was full.
There is no electrical fault interruption in that box
There is no electrical fault interruption in that box
Then that can't be good :)
How important are contaminants in liquid oxygen? Presumably this is another variable compared to the test site.
How important are contaminants in liquid oxygen? Presumably this is another variable compared to the test site.
Speaking from experience not to do with rockets; pure oxygen with a flammable contaminant (ex: hydrocarbons) is a bad day looking for a time & place to happen, especially where pipes change direction which can cause local heating.
Oh, I agree with terminology use but you have me curious for the mechanism for a "fast-fire" in a single tank under flight pressure helium...QuoteWere the tanks not at flight pressure with helium? How could that support combustion without liquid prop mixing and then ignite? I'm trying to understand what you are saying...
What I'm saying is that LOX and RP-1 combusting is not necessarily a "detonation." It can be a "deflagration," or fast fire. There is a difference. People seem to be throwing around the word "detonation" without fully understanding what it actually means.
I don't know what happened inside. Maybe a bulkhead leak/burst under a too-high pressure differential. Then internal "deflagration" followed by stage rupture. Or a COPV burst provided enough energy to intiate combustion of LOX with the overwrap material.
All I'm saying is that an internal "deflagration" could have caused what we saw in the video. It was not necessarily a "detonation" as was asserted upthread.
As a propulsion engineer I worked with solid propellants that could "deflagrate" (burn fast) and/or "detonate," and there is a technical difference, with a continuum between them, depending on how fast the deflagration proceeds. This is true also of the liquid-phase reactants involved here.
Seeing/hearing an event like this, observers may assume the event was the result of a "detonation," and my earlier example of the hydogen/oxygen balloon bursting shows that this is not necessarily true.
My problem with internal deflagration is that the first visible signs would not be that flash followed by a decrease in magnitude - it would be an ever-increasing thing, as more propellant and oxidizer got in contact.
Somehow, within one frame (say 30 mSec if it happened right after the previous frame), we went from nothing to a bright structure about, what, 6 m tall? Not quite supersonic in the "worst" case, but at least very close to it, and supersonic if it only took half a frame's time.
Then for a few frames it brightens up, diminishes, and then a secondary cloud of fluid appears, and everything catches fire and melts down.
So without speculating on what preceded the first external sign of trouble, my interpretation of what I see is a limited external explosion causing a shockwave, structural failure (maybe aided by a weakening caused by the root failure), and then the pressurized contents disperse and we have the big fire.
Faster video may tell a different tale of course. Lots could have happened within those 30 mSec.
How important are contaminants in liquid oxygen? Presumably this is another variable compared to the test site.
Speaking from experience not to do with rockets; pure oxygen with a flammable contaminant (ex: hydrocarbons) is a bad day looking for a time & place to happen, especially where pipes change direction which can cause local heating.
If you had enough contaminants in LOX to initiate this event, the whole tank should have be gone in an instant. This is not what happened.
How important are contaminants in liquid oxygen? Presumably this is another variable compared to the test site.
Speaking from experience not to do with rockets; pure oxygen with a flammable contaminant (ex: hydrocarbons) is a bad day looking for a time & place to happen, especially where pipes change direction which can cause local heating.
If you had enough contaminants in LOX to initiate this event, the whole tank should have be gone in an instant. This is not what happened.
Presumably contaminants don't just affect combustion. Could some materials be sensitive like the overwrapping of pressure vessels. Brainstorming further, how dry in terms of water ice particles does lox have to be - is it even possible to have ice contamination.
Apologies if this is annoying people, it's just that in the absence of new information about the event it is natural to think about external variables and the extent that they are understood. The vehicle is most likely the issue, or some transport handling
, from what informed people here have said.
So why are so many people blaming the COPV with no evidence to support that blame?
Or have I missed a whole load of COPV issues that would indicate they are a likely cause - someone said 60% likely above given previous issues- where does this number come from?
...
The diameter of the F9 is 12 feet. Using that as a rough yardstick, a supersonic expansion would have to be more than one F9 diameter per frame. It isn't.
...
Fireball diameter is actually TWICE the diameter of the F9 there.
One odd thing, that puzzles me, is the leftmost shape of the initial fireball. I have in mind those 3 "tongues". This implies, that at least this part of the explosion front should probably be subsonic and parts of it's propagation should have been obstructed in some ways.
Fireball diameter is actually TWICE the diameter of the F9 there.
One odd thing, that puzzles me, is the leftmost shape of the initial fireball. I have in mind those 3 "tongues". This implies, that at least this part of the explosion front should probably be subsonic and parts of it's propagation should have been obstructed in some ways.
No.
The middle "tongue" is the shape of the condensation cloud coming out of the LOX vent, reflecting (actually scattering) the light of the initial explosion. The shape above it is the same thing, it is the underside of the payload shroud lit up by the light of the initial explosion.
For what it's worth:
Fireball diameter is actually TWICE the diameter of the F9 there.
One odd thing, that puzzles me, is the leftmost shape of the initial fireball. I have in mind those 3 "tongues". This implies, that at least this part of the explosion front should probably be subsonic and parts of it's propagation should have been obstructed in some ways.
No.
The middle "tongue" is the shape of the condensation cloud coming out of the LOX vent, reflecting (actually scattering) the light of the initial explosion. The shape above it is the same thing, it is the underside of the payload shroud lit up by the light of the initial explosion.
Well, Your're right. In addition, the blast runs radially, not diameter-wise from one edge to another. This requires the initial fireball to be twice the size for it to be supersonic. Meaning that it should have been:
1. About 37ft in diameter
2. Almost perfectly circular
3. Have clear edge
Which it is not.
However this all assumes that the event started in the next millisecond after last frame. Possible, but not probable.
[about COPV failure] However IF they fail, then this results in enough carbon fiber, epoxy and aluminium dust and particles in order to turn the LOX into an explosive slurry. Following supersonic compression wave (due to high He pressure) will set this slurry off to a detonation. Not deflagration.Though a bursting COPV would be fast, it's not clear it could be supersonic in LOX. The speed of sound in helium is about 970 m/s at room temperature (http://www.engineeringtoolbox.com/speed-sound-gases-d_1160.html). Hence it will be about 500 m/s at cryogenic temperature. This is as fast as the bubble from the busted COPV could expand. The speed of sound in LOX is about 1000 m/s, according to the NASA report "Sound Speed Measurements in Liquid Oxygen-Liquid Nitrogen Mixtures" (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19850026994.pdf). So not supersonic.
[about COPV failure] However IF they fail, then this results in enough carbon fiber, epoxy and aluminium dust and particles in order to turn the LOX into an explosive slurry. Following supersonic compression wave (due to high He pressure) will set this slurry off to a detonation. Not deflagration.Though a bursting COPV would be fast, it's not clear it could be supersonic in LOX. The speed of sound in helium is about 970 m/s at room temperature (http://www.engineeringtoolbox.com/speed-sound-gases-d_1160.html). Hence it will be about 500 m/s at cryogenic temperature. This is as fast as the bubble from the busted COPV could expand. The speed of sound in LOX is about 1000 m/s, according to the NASA report "Sound Speed Measurements in Liquid Oxygen-Liquid Nitrogen Mixtures" (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19850026994.pdf). So not supersonic.
Also, at this point in the countdown, a burst COPV(or even all of them) won't rupture the tank from static overpressure alone (though they might from mechanical damage or shock). The COPVs combined only contain enough gas to pressurize the tank once the helium is heated. So without heating they can only fill something like 1/6 of the tank (depending on what temperature the Merlin heats them to). Since the tank is not 5/6 full (they are loading it at this point in the countdown), even the release of all the helium should not overpressurize the tank.
...
Also, at this point in the countdown, a burst COPV(or even all of them) won't rupture the tank from static overpressure alone (though they might from mechanical damage or shock). The COPVs combined only contain enough gas to pressurize the tank once the helium is heated. So without heating they can only fill something like 1/6 of the tank (depending on what temperature the Merlin heats them to). Since the tank is not 5/6 full (they are loading it at this point in the countdown), even the release of all the helium should not overpressurize the tank.
@Woods170,You either did not read or did not comprehend the disclaimer in my post.
So, your contact's gut feeling is a tank rupture followed by the ignition of the escaping liquids on such a short time-frame that it seems instantaneous to the human eye and most types of camera? That brings us back to the possibility of a flaw in the tanks or plumbing.
@Woods170,You either did not read or did not comprehend the disclaimer in my post.
So, your contact's gut feeling is a tank rupture followed by the ignition of the escaping liquids on such a short time-frame that it seems instantaneous to the human eye and most types of camera? That brings us back to the possibility of a flaw in the tanks or plumbing.
Also, the guy did not pull any conclusions with regards to the failure mode. I only asked him to have a look at the fireball event from the footage. That's what he did, and nothing else.
The only conclusion, that can be made from this post (and some adjacent ones), that you refer to, is that it is highly unlikely, that this blast was a detonation. And also, that it's incredibly difficult to determine something from this low quality image (and distant sound). That's all.
I was thinking of things in the sequence over a morning "cup of Joe"...There were early rumors of the event happening at T-3 and T-5. I would not put a lot of stock in those rumors, they were anonomous and of the "I heard" variety. It's certainly possible that they saw something in the data and were actively "aborting" the static fire but there is no evidence for it other than some speculation on this thread. The same update from SpaceX says, " At the time of the loss, the launch vehicle was vertical and in the process of being fueled for the test." So I don't think they were actively aborting.
From SpaceX press release:
http://www.spacex.com/news/2016/09/01/anomaly-updates
"- Yesterday, at SpaceX's Launch Complex 40 at Cape Canaveral Air Force Station, an anomaly took place about eight minutes in advance of a scheduled test firing of a Falcon 9 rocket.
- The anomaly on the pad resulted in the loss of the vehicle."
One could read that "an anomaly took place about eight minutes" so it was noted and did they continue with the sequence or abort (back out)? I'm trying to reconcile what happened between eight minutes and the originally reported five minutes. I was following it as the event occurred and when Jim posted what happened, I just sat there blinking at the screen. I thought I read all the posts but might have missed something... Anyone?
Thanks for your feedback. So the way I could read it is that they just saw "a funny" and either aborted or not and continued to work it is possible... Or the funny had nothing to do with it and another failure took place or something in the back out occurred... Anyone else please feel free to chime in...I was thinking of things in the sequence over a morning "cup of Joe"...There were early rumors of the event happening at T-3 and T-5. I would not put a lot of stock in those rumors, they were anonomous and of the "I heard" variety. It's certainly possible that they saw something in the data and were actively "aborting" the static fire but there is no evidence for it other than some speculation on this thread. The same update from SpaceX says, " At the time of the loss, the launch vehicle was vertical and in the process of being fueled for the test." So if they were already aware and aborting, they are being explicitly duplicitous.
From SpaceX press release:
http://www.spacex.com/news/2016/09/01/anomaly-updates
"- Yesterday, at SpaceX's Launch Complex 40 at Cape Canaveral Air Force Station, an anomaly took place about eight minutes in advance of a scheduled test firing of a Falcon 9 rocket.
- The anomaly on the pad resulted in the loss of the vehicle."
One could read that "an anomaly took place about eight minutes" so it was noted and did they continue with the sequence or abort (back out)? I'm trying to reconcile what happened between eight minutes and the originally reported five minutes. I was following it as the event occurred and when Jim posted what happened, I just sat there blinking at the screen. I thought I read all the posts but might have missed something... Anyone?
This does not rule out a data anomaly and the loss being separated in time, but I don't think they were "aborting" and I don't think we have any evidence that the events were separated in time. *shrug*
How important are contaminants in liquid oxygen? Presumably this is another variable compared to the test site.
Speaking from experience not to do with rockets; pure oxygen with a flammable contaminant (ex: hydrocarbons) is a bad day looking for a time & place to happen, especially where pipes change direction which can cause local heating.
If you had enough contaminants in LOX to initiate this event, the whole tank should have be gone in an instant. This is not what happened.
Presumably contaminants don't just affect combustion. Could some materials be sensitive like the overwrapping of pressure vessels. Brainstorming further, how dry in terms of water ice particles does lox have to be - is it even possible to have ice contamination.
Apologies if this is annoying people, it's just that in the absence of new information about the event it is natural to think about external variables and the extent that they are understood. The vehicle is most likely the issue, or some transport handling
, from what informed people here have said.
By quick googling I found a few reports on LOX contamination:
1. STUDY OF LIQUID OXYGEN CONTAMINATION from 1961: http://www.dtic.mil/dtic/tr/fulltext/u2/272377.pdf
2. Ignition of Aluminum by Impact in LOX — Influence of Contaminants https://www.astm.org/DIGITAL_LIBRARY/STP/PAGES/STP12492S.htm
The first one is rather old and I did not notice any particularly agressive contaminants in the text. Yes, there may be combustibles (most importantly acetylene and methane), but I think that in purities used today this should not be an issue.
The second one I have no access to, but the name is interesting in this context. So, if anyone can access it, this would be interesting.
Is spacex/nasa likely to have spectrum analysis? I good spectrum would indicate what metals were present in the initial flash. Do their cameras record colors in enough detail for this?Almost certainly not. Digital or analog cameras are going to just record red/green/blue channels, not enough information for spectral analysis. Even a film camera would just be recording those colors that the film emulsion responds to. To get any decent spectrographic information they would have to had a camera capable of breaking down the specific spectrum of the light set up and pointed at the rocket before the explosion.
I had a co-worker at one of my former jobs have a look at this. This guy used to characterize explosive properties of industrial gases. After some measuring, separating reflection from actual fireball, performing calculations, and assuming the time between the two frames is indeed 30 milliseconds, he made the following remarks:
...
....
So the way I could read it is that they just saw "a funny" and either aborted or not and continued to work it is possible... Or the funny had nothing to do with it and another failure took place or something in the back out occurred... Anyone else please feel free to chime in...
...
An explosion that can damage the skin would not move a fueled tank, not in a way that's visible in 3-4 frames...
Judo - CHOP!
It's concussion, not propulsion.
Watch any Bruce Lee movie... By the time the guy is flying backwards, his bones are already broken...
Especially if the tank was already damaged from an internal event that is invisible to the camera.
An explosion that can damage the skin would not move a fueled tank, not in a way that's visible in 3-4 frames...
Judo - CHOP!
It's concussion, not propulsion.
Watch any Bruce Lee movie... By the time the guy is flying backwards, his bones are already broken...
Especially if the tank was already damaged from an internal event that is invisible to the camera.
My uninformed and entirely unsupported GUESS... is that a venting valve for the RP1 tank stuck shut, and the common bulkhead inverted leading to... everything we saw. Highly unlikely.
First off, I recall someone (not sure who, there have been so many ideas tossed out) saying that they didn't feel this could be an external explosion, because they didn't see the stack move sideways in the first three or four frames after the initial fireball. The point being made was that an external explosion capable of piercing the tank, especially at the common bulkhead, would first noticeably push the whole stack to the side.Counterpoint- The Strongback is still attached to the rocket, dampening any horizontal motion with a structure specifically designed to dampen a less catastrophic horizontal motion.
Well, the initial flash is so sudden that, if it was created by gasses escaping from the stage and flaring into combustion as soon as they escaped, you would think this would cause a propulsive effect on the stack at that point, right? Equal to, or greater than, the force applied by an external explosion pushing against the stage, I would think.
And yet, the stack doesn't seem to move in response. And whatever happened, physics would tend to require that the stack would respond to what seems obviously to be an explosive force happening on just one side of the vehicle.
1/60 = 0.01666666 or 16.66~ milliseconds per frame...If so (I think the one I saw was 30 fps) then even more so...
(@ 1080p 60fps original source posted to Utube)
I keep seeing 30 milliseconds and 1/30 sec mentioned in many posts...
Am I wrong in saying those numbers quoted are in error??... :-\
For what it's worth:
Fireball diameter is actually TWICE the diameter of the F9 there.
One odd thing, that puzzles me, is the leftmost shape of the initial fireball. I have in mind those 3 "tongues". This implies, that at least this part of the explosion front should probably be subsonic and parts of it's propagation should have been obstructed in some ways.
No.
The middle "tongue" is the shape of the condensation cloud coming out of the LOX vent, reflecting (actually scattering) the light of the initial explosion. The shape above it is the same thing, it is the underside of the payload shroud lit up by the light of the initial explosion.
Well, Your're right. In addition, the blast runs radially, not diameter-wise from one edge to another. This requires the initial fireball to be twice the size for it to be supersonic. Meaning that it should have been:
1. About 37ft in diameter
2. Almost perfectly circular
3. Have clear edge
Which it is not.
However this all assumes that the event started in the next millisecond after last frame. Possible, but not probable.
I had a co-worker at one of my former jobs have a look at this. This guy used to characterize explosive properties of industrial gases. After some measuring, separating reflection from actual fireball, performing calculations, and assuming the time between the two frames is indeed 30 milliseconds, he made the following remarks:
1. This only looks like an explosion IF it started in the last 3-to-6 milliseconds before the second frame, and then only if the explosion is in a gas.
2. If the explosive was solid in nature then it probably started within the timeframe of exposure of the frame itself (solid explosives have much higher explosive velocities than gases).
3. The shape of the visible fireball is hard to interpret given all the reflection involved. Reflective elements from the TEL, payload shroud, second stage structure and the vapour cloud surrounding the vehicle, do a good job obscuring the actual shape of the fireball, combined with the poor image quality.
4. That said, and compensating for said reflective elements, the shape of the fireball does not support the notion of an explosive detonation taking place; too irregular.
5. Given best-case expansion velocities, assuming gases as the combustion medium, this can best be classed as a near-explosive conflagration, not as a true explosive detonation. He literally said: "With regards to the expansion velocity of the fireball, the initial blast looks very much like what was witnessed when Challenger was destroyed. And that wasn't an explosion either."
Disclaimer:
OK, that was just a quick look by a guy familiar with explosive properties. But it is important to remember that above remarks are based on a single piece of poor quality footage only, and without having access to any other sources related to this incident. So please, don't pull any conclusions based on above remarks and observations. That would be silly.
I urge folks to Use the "gear icon" at YouTube and pull down the 1080P @60fps version and step thru it frame by frame using , and . buttons... ;)1/60 = 0.01666666 or 16.66~ milliseconds per frame...If so (I think the one I saw was 30 fps) then even more so...
(@ 1080p 60fps original source posted to Utube)
I keep seeing 30 milliseconds and 1/30 sec mentioned in many posts...
Am I wrong in saying those numbers quoted are in error??... :-\
Musk stated that it was a fast fire, not an explosion since he stated that the crew escape system would have worked.
http://forum.nasaspaceflight.com/index.php?topic=40868.60
I would not be surprised to find the root cause has something to do with the properties of sub-cooled LOX, as opposed to regular boiling-point LOX. As many have pointed out, the US has not had a similar accident in about 50 years, a time span that includes many new generations of rockets. So it would seem the needed precautions for regular LOX and RP-1 are well understood. While it's certainly possible that SpaceX simply made some mistake, often the cause of an accident is some new material or procedure whose impact is not completely understood. The likely candidate here is sub-cooled LOX (they also use cooled RP-1, but kerosene at these temperatures is used all the time by airplanes, outdoor tank farms, campers, and other uses).
I have no specific suspect to relate this to the proximal cause. Candidates could be the higher viscosity causing larger losses and higher stresses in the plumbing, the ability of sub-cooled LOX to condense oxygen or nitrogen from the air, or perhaps some mechanical property of some material that is different enough at sub-cooled temperatures.
Musk stated that it was a fast fire, not an explosion since he stated that the crew escape system would have worked.
http://forum.nasaspaceflight.com/index.php?topic=40868.60
As has been discussed on this thread, the fast fire comment was taken to mean with respect to the crew escape system. I'm not sure why that distinction was necessary. It would be more impressive if the crew escape system could separate in the event of an "explosion". Several posters have provided information based on the size of the plume and the frame rate of the video that shows this meets "accepted" definitions of an "explosion", and that "fast fire" is really not a typical term. I'm no expert, but that loud BANG that occurs with the flash of light sure sounds like an explosion to me.
Musk stated that it was a fast fire, not an explosion since he stated that the crew escape system would have worked.
http://forum.nasaspaceflight.com/index.php?topic=40868.60
As has been discussed on this thread, the fast fire comment was taken to mean with respect to the crew escape system. I'm not sure why that distinction was necessary. It would be more impressive if the crew escape system could separate in the event of an "explosion". Several posters have provided information based on the size of the plume and the frame rate of the video that shows this meets "accepted" definitions of an "explosion", and that "fast fire" is really not a typical term. I'm no expert, but that loud BANG that occurs with the flash of light sure sounds like an explosion to me.
I didn't read all of this thread. But I understood the fast fire tweet as indicating that it started off as a fire which means that they would have had time to trigger the escape system even if it was milliseconds.
First off, I recall someone (not sure who, there have been so many ideas tossed out) saying that they didn't feel this could be an external explosion, because they didn't see the stack move sideways in the first three or four frames after the initial fireball. The point being made was that an external explosion capable of piercing the tank, especially at the common bulkhead, would first noticeably push the whole stack to the side.
I urge folks to Use the "gear icon" at YouTube and pull down the 1080P @60fps version and step thru it frame by frame using , and . buttons... ;)1/60 = 0.01666666 or 16.66~ milliseconds per frame...If so (I think the one I saw was 30 fps) then even more so...
(@ 1080p 60fps original source posted to Utube)
I keep seeing 30 milliseconds and 1/30 sec mentioned in many posts...
Am I wrong in saying those numbers quoted are in error??... :-\
If that option is not shown... suggest use the Google Chrome Browser to solve that issue...
60FPS 1080p cameras are a thing and the source video could have been uploaded as such. Are you sure this was interpolated?I urge folks to Use the "gear icon" at YouTube and pull down the 1080P @60fps version and step thru it frame by frame using , and . buttons... ;)1/60 = 0.01666666 or 16.66~ milliseconds per frame...If so (I think the one I saw was 30 fps) then even more so...
(@ 1080p 60fps original source posted to Utube)
I keep seeing 30 milliseconds and 1/30 sec mentioned in many posts...
Am I wrong in saying those numbers quoted are in error??... :-\
If that option is not shown... suggest use the Google Chrome Browser to solve that issue...
The 60fps version is an interpolated up-conversion based on the original upload at 30fps. If you are watching the video at 60fps and stepping through it frame by frame, just remember that every other frame was completely invented by an algorithm.
Agreed... the file I reviewed was 1080P @ 60fps... My take was it WAS at the source file spec... ???60FPS 1080p cameras are a thing and the source video could have been uploaded as such. Are you sure this was interpolated?I urge folks to Use the "gear icon" at YouTube and pull down the 1080P @60fps version and step thru it frame by frame using , and . buttons... ;)1/60 = 0.01666666 or 16.66~ milliseconds per frame...If so (I think the one I saw was 30 fps) then even more so...
(@ 1080p 60fps original source posted to Utube)
I keep seeing 30 milliseconds and 1/30 sec mentioned in many posts...
Am I wrong in saying those numbers quoted are in error??... :-\
If that option is not shown... suggest use the Google Chrome Browser to solve that issue...
The 60fps version is an interpolated up-conversion based on the original upload at 30fps. If you are watching the video at 60fps and stepping through it frame by frame, just remember that every other frame was completely invented by an algorithm.
It won't be the exact source file that was uploaded as YouTube often re-encodes the video for playback compatibility and bitrate conformance, but it should be close.Agreed... the file I reviewed was 1080P @ 60fps... My take was it WAS the source file spec... ???60FPS 1080p cameras are a thing and the source video could have been uploaded as such. Are you sure this was interpolated?I urge folks to Use the "gear icon" at YouTube and pull down the 1080P @60fps version and step thru it frame by frame using , and . buttons... ;)1/60 = 0.01666666 or 16.66~ milliseconds per frame...If so (I think the one I saw was 30 fps) then even more so...
(@ 1080p 60fps original source posted to Utube)
I keep seeing 30 milliseconds and 1/30 sec mentioned in many posts...
Am I wrong in saying those numbers quoted are in error??... :-\
If that option is not shown... suggest use the Google Chrome Browser to solve that issue...
The 60fps version is an interpolated up-conversion based on the original upload at 30fps. If you are watching the video at 60fps and stepping through it frame by frame, just remember that every other frame was completely invented by an algorithm.
Moving objects acted as they should frame to frame... (birds, fragments, etc)
Agreed... I have uploaded 1080p 60fps drone and camcorder footage to YouTube in the past...It won't be the exact source file that was uploaded as YouTube often re-encodes the video for playback compatibility and bitrate conformance, but it should be close.Agreed... the file I reviewed was 1080P @ 60fps... My take was it WAS the source file spec... ???60FPS 1080p cameras are a thing and the source video could have been uploaded as such. Are you sure this was interpolated?I urge folks to Use the "gear icon" at YouTube and pull down the 1080P @60fps version and step thru it frame by frame using , and . buttons... ;)1/60 = 0.01666666 or 16.66~ milliseconds per frame...If so (I think the one I saw was 30 fps) then even more so...
(@ 1080p 60fps original source posted to Utube)
I keep seeing 30 milliseconds and 1/30 sec mentioned in many posts...
Am I wrong in saying those numbers quoted are in error??... :-\
If that option is not shown... suggest use the Google Chrome Browser to solve that issue...
The 60fps version is an interpolated up-conversion based on the original upload at 30fps. If you are watching the video at 60fps and stepping through it frame by frame, just remember that every other frame was completely invented by an algorithm.
Moving objects acted as they should frame to frame... (birds, fragments, etc)
I urge folks to Use the "gear icon" at YouTube and pull down the 1080P @60fps version and step thru it frame by frame using , and . buttons... ;)1/60 = 0.01666666 or 16.66~ milliseconds per frame...If so (I think the one I saw was 30 fps) then even more so...
(@ 1080p 60fps original source posted to Utube)
I keep seeing 30 milliseconds and 1/30 sec mentioned in many posts...
Am I wrong in saying those numbers quoted are in error??... :-\
If that option is not shown... suggest use the Google Chrome Browser to solve that issue...
First off, I recall someone (not sure who, there have been so many ideas tossed out) saying that they didn't feel this could be an external explosion, because they didn't see the stack move sideways in the first three or four frames after the initial fireball. The point being made was that an external explosion capable of piercing the tank, especially at the common bulkhead, would first noticeably push the whole stack to the side.
Another minor hypothesis to shoot down.
The initial event occurred on the side of the tower/F9 closest to the camera.
Rationale:
There are multiple reflective bodies in the field of view, the oxy-globe, and 3 of the lightning towers, and some roof sections towards the bottom.
at Frame 0 as reference, note which parts of the towers and globe are reflecting. Then toggle to Frame 1 and note the difference.
Compare that with Frame 20 or 30 or 40, and note which parts of the towers and globe are reflecting.
What I think I see is that a much larger portion of the rear towers and globe are illuminated as the event proceeds and surrounds the F9 completely, vs a much narrower illumination of the rear towers & globe at Frame 1. To me that suggests that the event is partially obscured to the rear towers and globe by the F9 and its tower.
Does anyone have the ability to ray-trace cylinders & globes from different point source illuminations and see if you can duplicate the reflections based on where the source is? I guess you'd also have to have a full 3-D model of the F9 and tower to get it right.
Does anyone know the radius of the globe and the top parts of the lightning towers?
First off, I recall someone (not sure who, there have been so many ideas tossed out) saying that they didn't feel this could be an external explosion, because they didn't see the stack move sideways in the first three or four frames after the initial fireball. The point being made was that an external explosion capable of piercing the tank, especially at the common bulkhead, would first noticeably push the whole stack to the side.
I can not parse the difference between a slow explosion and a fast fire, but the stack definitely moves. Pardon the crappy tech in this video, but it does illustrate the movement. All video credit to the dedicated folk at USLaunchReport for giving us something to chew on while we await word from the people with much more info and insight.
https://www.youtube.com/watch?v=SQ8ZBPRiLXs
Enjoy, Matthew
That appears to be the exact same video, mirrored left-to-right, with a slow motion interpolation applied that's mostly just amplifying compression artifacts. I wouldn't give it any credence at all.
How important are contaminants in liquid oxygen? Presumably this is another variable compared to the test site.
Speaking from experience not to do with rockets; pure oxygen with a flammable contaminant (ex: hydrocarbons) is a bad day looking for a time & place to happen, especially where pipes change direction which can cause local heating.
If you had enough contaminants in LOX to initiate this event, the whole tank should have be gone in an instant. This is not what happened.
Presumably contaminants don't just affect combustion. Could some materials be sensitive like the overwrapping of pressure vessels. Brainstorming further, how dry in terms of water ice particles does lox have to be - is it even possible to have ice contamination.
Apologies if this is annoying people, it's just that in the absence of new information about the event it is natural to think about external variables and the extent that they are understood. The vehicle is most likely the issue, or some transport handling
, from what informed people here have said.
By quick googling I found a few reports on LOX contamination:
1. STUDY OF LIQUID OXYGEN CONTAMINATION from 1961: http://www.dtic.mil/dtic/tr/fulltext/u2/272377.pdf
2. Ignition of Aluminum by Impact in LOX — Influence of Contaminants https://www.astm.org/DIGITAL_LIBRARY/STP/PAGES/STP12492S.htm
The first one is rather old and I did not notice any particularly agressive contaminants in the text. Yes, there may be combustibles (most importantly acetylene and methane), but I think that in purities used today this should not be an issue.
The second one I have no access to, but the name is interesting in this context. So, if anyone can access it, this would be interesting.
Here is a personal experience with oxygen contamination is a gaseous system. I had a 2" isolation ball valve explode after being in service for many years. The valve was last cycled 5 minutes prior to the incident and no oxygen flow was occurring (no delta P across the valve). The failure was traced to comtaminated gaseous oxygen delivery from the supplier. This was determined only after filters were installed on the fill lines and upon inspection revealed organics. The suppliers investigation found their techs were failing to cap the the fill line from their factory to the delivery trucks. Bugs were making a home in the line. Just goes to show it can happen!
Needless to say there was extensive damage and required significant rework. The fill filters are required to be inspected after EVERY delivery now. A lesson learned.
Another minor hypothesis to shoot down.
The initial event occurred on the side of the tower/F9 closest to the camera.
Rationale:
There are multiple reflective bodies in the field of view, the oxy-globe, and 3 of the lightning towers, and some roof sections towards the bottom.
at Frame 0 as reference, note which parts of the towers and globe are reflecting. Then toggle to Frame 1 and note the difference.
Compare that with Frame 20 or 30 or 40, and note which parts of the towers and globe are reflecting.
What I think I see is that a much larger portion of the rear towers and globe are illuminated as the event proceeds and surrounds the F9 completely, vs a much narrower illumination of the rear towers & globe at Frame 1. To me that suggests that the event is partially obscured to the rear towers and globe by the F9 and its tower.
Does anyone have the ability to ray-trace cylinders & globes from different point source illuminations and see if you can duplicate the reflections based on where the source is? I guess you'd also have to have a full 3-D model of the F9 and tower to get it right.
Does anyone know the radius of the globe and the top parts of the lightning towers?
So far you have tracked every bug, bird, and square centimeter of debris within the ? number of miles between the event and the camera, and now you want us to start tracking every ray of light? To prove one of the few things that have been obvious from the beginning?
First off, I recall someone (not sure who, there have been so many ideas tossed out) saying that they didn't feel this could be an external explosion, because they didn't see the stack move sideways in the first three or four frames after the initial fireball. The point being made was that an external explosion capable of piercing the tank, especially at the common bulkhead, would first noticeably push the whole stack to the side.
I can not parse the difference between a slow explosion and a fast fire, but the stack definitely moves. Pardon the crappy tech in this video, but it does illustrate the movement. All video credit to the dedicated folk at USLaunchReport for giving us something to chew on while we await word from the people with much more info and insight.
https://www.youtube.com/watch?v=SQ8ZBPRiLXs
Enjoy, Matthew
So, here's my bit. Can't find where anyone has talked about inadvertent activation of the flight termination system. Rare, but it has happened before. And Spacex has been talking about a new automatic FTS system. Was that implemented yet?
Lots of interesting and entertaining speculation while we wait for facts from SpaceX.
So, here's my bit. Can't find where anyone has talked about inadvertent activation of the flight termination system. Rare, but it has happened before. And Spacex has been talking about a new automatic FTS system. Was that implemented yet?
Everyone is focused on trying to mix fuel and lox, or overpressurization, to get to an explosion, but aren't there explosives attached right to the side of the stages? The idea is to "unzip" the tanks upon activation, right?
Apologies in advance if I've missed this in prior discussions.
So, here's my bit. Can't find where anyone has talked about inadvertent activation of the flight termination system. Rare, but it has happened before. And Spacex has been talking about a new automatic FTS system. Was that implemented yet?
Another minor hypothesis to shoot down.... i think this is also supported by the diffraction spikes being at the edge of the visible rocket, thus likely being 'behind' the rocket in the USLaunch vid
The initial event occurred on the side of the tower/F9 closest to the camera.
Rationale:
There are multiple reflective bodies in the field of view, the oxy-globe, and 3 of the lightning towers, and some roof sections towards the bottom.
So far you have tracked every bug, bird, and square centimeter of debris within the ? number of miles between the event and the camera, and now you want us to start tracking every ray of light? To prove one of the few things that have been obvious from the beginning?
So far you have tracked every bug, bird, and square centimeter of debris within the ? number of miles between the event and the camera, and now you want us to start tracking every ray of light? To prove one of the few things that have been obvious from the beginning?
Another minor hypothesis to shoot down.... i think this is also supported by the diffraction spikes being at the edge of the visible rocket, thus likely being 'behind' the rocket in the USLaunch vid
The initial event occurred on the side of the tower/F9 closest to the camera.
Rationale:
There are multiple reflective bodies in the field of view, the oxy-globe, and 3 of the lightning towers, and some roof sections towards the bottom.
1/60 = 0.01666666 or 16.66~ milliseconds per frame...
(@ 1080p 60fps original source posted to Utube)
I keep seeing 30 milliseconds and 1/30 sec mentioned in many posts...
Am I wrong in saying those numbers quoted are in error??... :-\
On edit...
As to movement... The rocket weighed several 100's of TONS at the moment of 'Flash'... ???
Movement?... I think not much... that can be seen or even recorded...
I just thought of something. Since this did not occur at launch or in flight, is the FAA really in charge of the investigation? Or is it the Air Force, since it is a ground accident on their property.?
First off, I recall someone (not sure who, there have been so many ideas tossed out) saying that they didn't feel this could be an external explosion, because they didn't see the stack move sideways in the first three or four frames after the initial fireball. The point being made was that an external explosion capable of piercing the tank, especially at the common bulkhead, would first noticeably push the whole stack to the side.
I can not parse the difference between a slow explosion and a fast fire, but the stack definitely moves. Pardon the crappy tech in this video, but it does illustrate the movement. All video credit to the dedicated folk at USLaunchReport for giving us something to chew on while we await word from the people with much more info and insight.
https://www.youtube.com/watch?v=SQ8ZBPRiLXs
Enjoy, Matthew
OMG -- the top of the payload shroud moved forward and to the right...
da da DA!!!
:)
I just thought of something. Since this did not occur at launch or in flight, is the FAA really in charge of the investigation? Or is it the Air Force, since it is a ground accident on their property.?
First off, I recall someone (not sure who, there have been so many ideas tossed out) saying that they didn't feel this could be an external explosion, because they didn't see the stack move sideways in the first three or four frames after the initial fireball. The point being made was that an external explosion capable of piercing the tank, especially at the common bulkhead, would first noticeably push the whole stack to the side.
I can not parse the difference between a slow explosion and a fast fire, but the stack definitely moves. Pardon the crappy tech in this video, but it does illustrate the movement. All video credit to the dedicated folk at USLaunchReport for giving us something to chew on while we await word from the people with much more info and insight.
https://www.youtube.com/watch?v=SQ8ZBPRiLXs
Enjoy, Matthew
Just checked the Updates section and there was an SX press release from the 2nd. Interesting take awaysOops. As someone reminded me, what about October?
was
They state their 2nd FL launch pad is on schedule for being F9/FH ready by November. So Florida launches resume NET November 1st (Using Musk level optimism :) ) unless they can repair this pad in less than 25 days.
I've no feel for how damaged the pad and TEL have been damaged. To a layman like me it looks really badly damaged with months of work to rebuild it but is it?
I just thought of something. Since this did not occur at launch or in flight, is the FAA really in charge of the investigation? Or is it the Air Force, since it is a ground accident on their property.?Good point but I thought there was a lot of debate around this for commercial space flights with NASA pushing hard for jurisdiction but (IIRC) FAA getting it under their commercial spaceflight office.
So far you have tracked every bug, bird, and square centimeter of debris within the ? number of miles between the event and the camera, and now you want us to start tracking every ray of light? To prove one of the few things that have been obvious from the beginning?
Yes and I want a color comparison of the initial flash to rp1/lox exhaust and solid rocket motor with aluminum. What does the color of the flash match for component materials....
I just thought of something. Since this did not occur at launch or in flight, is the FAA really in charge of the investigation? Or is it the Air Force, since it is a ground accident on their property.?
First off, I recall someone (not sure who, there have been so many ideas tossed out) saying that they didn't feel this could be an external explosion, because they didn't see the stack move sideways in the first three or four frames after the initial fireball. The point being made was that an external explosion capable of piercing the tank, especially at the common bulkhead, would first noticeably push the whole stack to the side.
I can not parse the difference between a slow explosion and a fast fire, but the stack definitely moves. Pardon the crappy tech in this video, but it does illustrate the movement. All video credit to the dedicated folk at USLaunchReport for giving us something to chew on while we await word from the people with much more info and insight.
https://www.youtube.com/watch?v=SQ8ZBPRiLXs
Enjoy, Matthew
Very clever approach. I'm jealous that I didn't think of it.
It looks actually like it's moving to the right and dropping a bit. I would interpret it as a structural collapse rather than motion imparted by an explosion, however defined.
OK, gang... using my geologic engineering background, i believe i have a plausible explanation of the *ploink* and rumble on the vid. YES is DOES COME FROM THE JUNKYARD!, but the explosion and subsequent fireball ARE to blame. Since the S1 is attached to the pad/ground, it transmits the pressure wave directly to the ground. This is why it registered on seismic equipment. since pressure waves travel much faster through the ground than in the compressible air, the transient noises in the video are caused by the explosion. The shock traveling through the ground will arrive to the microphone location before the sound traveling in the air. This shockwave/impulse caused something in the yard to tilt,rub,bang or rattle . Initial explosion shock arrival IS the *ploink* and fireball/collapse of the stack is the rattle. That should put everything to bed... what do you think Chris?I was checking for seismic data the a couple of days ago but could not locate a station for Florida. Perhaps you have better luck. I did find news of a quake offshore from Daytona beach on July 17th which was interesting...
this will be for pressure or P-Wave impulses
since the coastal area of CCAFS is mostly unconsolidated sediment & sand, one can use 1000 meters/sec as velocity.
Here's the study from 2011 by University of Florida regarding seismic energy propagation in FLA
http://www.dot.state.fl.us/research-center/Completed_Proj/Summary_SMO/FDOT_BDK75_977-01_rpt.pdf
I'll let you have fun with the maths
First off, I recall someone (not sure who, there have been so many ideas tossed out) saying that they didn't feel this could be an external explosion, because they didn't see the stack move sideways in the first three or four frames after the initial fireball. The point being made was that an external explosion capable of piercing the tank, especially at the common bulkhead, would first noticeably push the whole stack to the side.
I can not parse the difference between a slow explosion and a fast fire, but the stack definitely moves. Pardon the crappy tech in this video, but it does illustrate the movement. All video credit to the dedicated folk at USLaunchReport for giving us something to chew on while we await word from the people with much more info and insight.
https://www.youtube.com/watch?v=SQ8ZBPRiLXs
Enjoy, Matthew
Very clever approach. I'm jealous that I didn't think of it.
It looks actually like it's moving to the right and dropping a bit. I would interpret it as a structural collapse rather than motion imparted by an explosion, however defined.
Could be payload pivoting to the right as S2 moves left. (pivoting at the point of the TEL arms). Or right side of S2 collapsing before left side (and payload falling right as you said).
A thought I have wrt this video and the ensuing discussion is thatFirst off, I recall someone (not sure who, there have been so many ideas tossed out) saying that they didn't feel this could be an external explosion, because they didn't see the stack move sideways in the first three or four frames after the initial fireball. The point being made was that an external explosion capable of piercing the tank, especially at the common bulkhead, would first noticeably push the whole stack to the side.
I can not parse the difference between a slow explosion and a fast fire, but the stack definitely moves. Pardon the crappy tech in this video, but it does illustrate the movement. All video credit to the dedicated folk at USLaunchReport for giving us something to chew on while we await word from the people with much more info and insight.
https://www.youtube.com/watch?v=SQ8ZBPRiLXs
Enjoy, Matthew
Very clever approach. I'm jealous that I didn't think of it.
It looks actually like it's moving to the right and dropping a bit. I would interpret it as a structural collapse rather than motion imparted by an explosion, however defined.
Could be payload pivoting to the right as S2 moves left. (pivoting at the point of the TEL arms). Or right side of S2 collapsing before left side (and payload falling right as you said).
I just thought of something. Since this did not occur at launch or in flight, is the FAA really in charge of the investigation? Or is it the Air Force, since it is a ground accident on their property.?
I believe that the FAA/AST license encompasses pre-launch preparations, though when they deem that process begins eludes me. But I'd bet they all claim authority over the wet-dress.
I know they tried to claim jurisdiction over Rotary twenty years ago, saying that we needed their approval to build our manufacturing facilities in Mojave, even before we had begun any licensing process.
A very good observation, young weed hopper, and one I thought about too. Your observation is most credible, but...
The problem is locking the field of view which I didn't show in the image posted. Granted long distance atmospheric distortion and such, and other things, there are multiple frames that show this. I merged the two most obvious frames, but, there are others. You are correct that the brightening is not uniform, and comes from the right to the left, which could create an optical illusion separate from actual motion, but, I looked at that over multiple frames and focused on finding the fairing irrespective of illumination, which is, as you suggest, the right thing to do, and concluded, IMHO, it actually rotates right and down. If you have Photoshop, try selecting levels at various values to try to enhance the fairing. You'll have to change the tolerance for each frame, since the illumination levels are changing frame to frame.
The original data is there to see. RIP it and post please if you're sure I'm wrong. :)
I welcome this debate and am willing to post multiple images, but the simple fact is as I see it, the fairing rotates towards the right and drops.
It doesn't go up ever in any mode I've looked at.
I still propose IMHO that the initial detonation is external to the F9, and in front of the tower facing the camera... :)
Elon's will be done. :)
5. Given best-case expansion velocities, assuming gases as the combustion medium, this can best be classed as a near-explosive conflagration, not as a true explosive detonation. He literally said: "With regards to the expansion velocity of the fireball, the initial blast looks very much like what was witnessed when Challenger was destroyed. And that wasn't an explosion either."The National Fire Protection Association defines a detonation as "propagation of a combustion zone at a velocity greater than the speed of sound in the unreacted medium". It defines an explosion as "the sudden conversion of potential energy (chemical or mechanical) into kinetic energy with the production and release of gases under pressure, or the release of gas under pressure. These high-pressure gases then do mechanical work such as moving, changing, or shattering nearby materials."
Wow - a new piece of evidence. And consistent with an external force pushing at the common bulkhead with the payload pivoting clockwise around the clamp.
I can not parse the difference between a slow explosion and a fast fire, but the stack definitely moves. Pardon the crappy tech in this video, but it does illustrate the movement. All video credit to the dedicated folk at USLaunchReport for giving us something to chew on while we await word from the people with much more info and insight.
Is there any definitive proof that the center of the lens flair is in fact where the LOX fuel line is?
I get the feeling that problem is going to be the use of the densified propellant. It could be that every time the falcon was loaded with the superchilled LOX there was a small chance that there would be an explosion and it was just a matter of time. I little bit of googling shows that a lot of people were concerned with the use of the new denser fuel.
My greatest fear is that the investigation shows that there are unresolvable issues with the densified fuel and spacex is ordered to stop using it. This would create all kinds of issues even assuming no changes need to be made to the rocket.
Is there any definitive proof that the center of the lens flair is in fact where the LOX fuel line is?
Is there any definitive proof that the center of the lens flair is in fact where the LOX fuel line is?
The contrary seems more likely. From left to right, the Amos6 lens flare, the same point in the frame before the conflagration, the cross section from the Falcon 9 User's Guide v2.0, and the JCSAT14 static fire with the TE retracted, and no payload. The LOX fuel line is attached much lower than the epicentre.
A very good observation, young weed hopper, and one I thought about too. Your observation is most credible, but...
The problem is locking the field of view which I didn't show in the image posted. Granted long distance atmospheric distortion and such, and other things, there are multiple frames that show this. I merged the two most obvious frames, but, there are others. You are correct that the brightening is not uniform, and comes from the right to the left, which could create an optical illusion separate from actual motion, but, I looked at that over multiple frames and focused on finding the fairing irrespective of illumination, which is, as you suggest, the right thing to do, and concluded, IMHO, it actually rotates right and down. If you have Photoshop, try selecting levels at various values to try to enhance the fairing. You'll have to change the tolerance for each frame, since the illumination levels are changing frame to frame.
The original data is there to see. RIP it and post please if you're sure I'm wrong. :)
I welcome this debate and am willing to post multiple images, but the simple fact is as I see it, the fairing rotates towards the right and drops.
It doesn't go up ever in any mode I've looked at.
I still propose IMHO that the initial detonation is external to the F9, and in front of the tower facing the camera... :)
Elon's will be done. :)
As of sunset September 6th, the strongback is still vertical as I photographed it. No great details as its over 10.5 miles away in atmospheric wind and heat shimmer
As of sunset September 6th, the strongback is still vertical as I photographed it. No great details as its over 10.5 miles away in atmospheric wind and heat shimmer
What type of lens do you have to see something 10 miles away?
In the picture there seems to be some kind of structure running up the side of the second stage that ends around where the lox tank would start. This would seem to imply a failure of the lox lines.
Using the single frame advance (and many thanks to the person upthread who shared that trick for Youtube vids) I detect no motion on the part of the payload faring. If you lay a ruler on the screen at the beginning, then as the light climbs the fairing, the only change is the background washout along the upper left curve. The right edge remains absolutely clear and never shifts as the cloud climbs to obscure it.
Some really interesting (as well as some not so good) work with the footage....although it makes me think we should have a whip round/collection for the USLaunchReport guys at some point, because without them having a camera on these static fires we'd have no footage (SpaceX had cameras on it, but for internal purposes).
This is probably based on mistaken reporting and shouldn't be considered an update. Various reports on financial channels state that Spacecom will be pursuing/expecting $50M from SpaceX and $200M from the satellite manufacturer. Not sure why they're expecting to collect from the manufacturer. Anyhow the implication is SpaceX isn't on the hook for the satellite costs.
http://arstechnica.com/science/2016/09/spacex-explosion-amos-6-satellite-owner-demands-50-million-dollars/
Why would the satellite manufacturer agree to refund unless their satellite somehow caused the incident?
Might be just venting hot air to impress the Chinese.
As of sunset September 6th, the strongback is still vertical as I photographed it. No great details as its over 10.5 miles away in atmospheric wind and heat shimmer
Why would the satellite manufacturer agree to refund unless their satellite somehow caused the incident?
Might be just venting hot air to impress the Chinese.
We know that the payload was insured as marine cargo until the ignition for launch. I would think that the manufacturer signed this insurance policy and will pass the payout on to Spacecom.
As of sunset September 6th, the strongback is still vertical as I photographed it. No great details as its over 10.5 miles away in atmospheric wind and heat shimmer
I don't see this as an optical illusion. This is a composite of prior to the event and just before the fairing is obscured by the event. Grey is the before. I've cropped out most of the sky. While the motion is optically illuminating from lower right to upper left, and that could produce the illusion you describe, the outline of the fairing you can see is still visible, and it's lower and tilted to the right.
If you have the correct tools, you can cut out the before, rotate and drop it, and it's a perfect matchup for the after.
So anyone care to speculate if that left-most lightning mast is scorched (it was probably downwind of the fire and smoke plume), just dirty, or just dark due to distance/lighting/photo processing? I understand the the masts are fiberglass, mounted on the steel tower bases.
We know that the payload was insured as marine cargo until the ignition for launch. I would think that the manufacturer signed this insurance policy and will pass the payout on to Spacecom.
I don't see this as an optical illusion. This is a composite of prior to the event and just before the fairing is obscured by the event. Grey is the before. I've cropped out most of the sky. While the motion is optically illuminating from lower right to upper left, and that could produce the illusion you describe, the outline of the fairing you can see is still visible, and it's lower and tilted to the right.
If you have the correct tools, you can cut out the before, rotate and drop it, and it's a perfect matchup for the after.
Could you, guys, elaborate, what difference does it make? Moved, moved a little, did not move at all - what conclusions will you make out of that?
Are there any pipes/tubes running up and down on the side of the tower closest to the camera? If so, does anyone know what's supposed to be in them?
Are there any pipes/tubes running up and down on the side of the tower closest to the camera? If so, does anyone know what's supposed to be in them?
Nothing, they are just lightning towers
Are there any pipes/tubes running up and down on the side of the tower closest to the camera? If so, does anyone know what's supposed to be in them?
Nothing, they are just lightning towers
Are there any pipes/tubes running up and down on the side of the tower closest to the camera? If so, does anyone know what's supposed to be in them?
Nothing, they are just lightning towers
Jim, I obviously didn't state my question clearly. This is the area that my question referred to.
Still nothing
Are there any pipes/tubes running up and down on the side of the tower closest to the camera? If so, does anyone know what's supposed to be in them?
Nothing, they are just lightning towers
Not clear if glennfish meant the T/E or lightning towers. If lightning tower, they're tubes with (I think, if they follow industry standards), a thick grounding conductor running their length to a deeply-driven grounding rod. If he's referring to the T/E, I think it's been well established that the only thing running up past the S2 umbilicals at the base of the stage would be conditioned air/N2 for payload purge, and hydraulics for the clamps. Is that a good summary, Jim?
Are there any pipes/tubes running up and down on the side of the tower closest to the camera? If so, does anyone know what's supposed to be in them?
Nothing, they are just lightning towers
Jim, I obviously didn't state my question clearly. This is the area that my question referred to.
Are there any pipes/tubes running up and down on the side of the tower closest to the camera? If so, does anyone know what's supposed to be in them?
Nothing, they are just lightning towers
Not clear if glennfish meant the T/E or lightning towers. If lightning tower, they're tubes with (I think, if they follow industry standards), a thick grounding conductor running their length to a deeply-driven grounding rod. If he's referring to the T/E, I think it's been well established that the only thing running up past the S2 umbilicals at the base of the stage would be conditioned air/N2 for payload purge, and hydraulics for the clamps. Is that a good summary, Jim?
Are there any materials on the T/E in that area that could become sensitized after repeated exposure to low temperatures and liquid oxygen? I'm reminded of the gasket explosions that destroyed several of the early X-planes.
Lessons learned long ago that are no longer repeated
Lessons learned long ago that are no longer repeated
Yes, but then again how many launch providers have their vehicle blow up during a tanking operation these days?
Are there any pipes/tubes running up and down on the side of the tower closest to the camera? If so, does anyone know what's supposed to be in them?
Nothing, they are just lightning towers
Not clear if glennfish meant the T/E or lightning towers. If lightning tower, they're tubes with (I think, if they follow industry standards), a thick grounding conductor running their length to a deeply-driven grounding rod. If he's referring to the T/E, I think it's been well established that the only thing running up past the S2 umbilicals at the base of the stage would be conditioned air/N2 for payload purge, and hydraulics for the clamps. Is that a good summary, Jim?
Did you say hydraulics for the clamps? Any idea what the working fluid is in those hydraulics, and the capacity, and the working pressure?
Lessons learned long ago that are no longer repeated
Yes, but then again how many launch providers have their vehicle blow up during a tanking operation these days?
Because they found a new way to do it.
Are there any pipes/tubes running up and down on the side of the tower closest to the camera? If so, does anyone know what's supposed to be in them?
Nothing, they are just lightning towers
Not clear if glennfish meant the T/E or lightning towers. If lightning tower, they're tubes with (I think, if they follow industry standards), a thick grounding conductor running their length to a deeply-driven grounding rod. If he's referring to the T/E, I think it's been well established that the only thing running up past the S2 umbilicals at the base of the stage would be conditioned air/N2 for payload purge, and hydraulics for the clamps. Is that a good summary, Jim?
Did you say hydraulics for the clamps? Any idea what the working fluid is in those hydraulics, and the capacity, and the working pressure?
Sanity check: how big was the initial blast? How much hydraulic fluid would have been required for a blast of that size? Now consider the speed of the initial blast. The fuel and oxidizer would already have had to have been mixed. Could such an enormous amount of hydraulic fluid have leaked without anyone noticing, let alone leaked and mixed with oxygen, all without blowing away in the wind?
I can't see how.
Thoughts.... this looks like a elongated illumination source, more tall than wide, kinda like you'd see from a shop light.
So, that means that, in my latest adaptation of the pic of an F9 on the pad, the conduit that runs up to the S-bend is the AC line. So, the conduit to its left in this picture, which terminates in the padded boxes I had assumed was an AC filter complex, seems to be completely unconnected from the AC system.
Which begs the question, what is inside these padded boxes? They are connected to the TEL and are the termination of the largest main conduit that reaches this far up the TEL. They are also right around where the initial flash is seen. They also show a number of different electrical connections, especially on some smaller panels attached to the whole complex on the camera-facing side of the TEL. And there are three relatively small small pipe terminations below that appear to have orange cover booties on them that are visible below this complex, which could be liquid, gas or electrical terminations.
So, that means that, in my latest adaptation of the pic of an F9 on the pad, the conduit that runs up to the S-bend is the AC line. So, the conduit to its left in this picture, which terminates in the padded boxes I had assumed was an AC filter complex, seems to be completely unconnected from the AC system.
Which begs the question, what is inside these padded boxes? They are connected to the TEL and are the termination of the largest main conduit that reaches this far up the TEL. They are also right around where the initial flash is seen. They also show a number of different electrical connections, especially on some smaller panels attached to the whole complex on the camera-facing side of the TEL. And there are three relatively small small pipe terminations below that appear to have orange cover booties on them that are visible below this complex, which could be liquid, gas or electrical terminations.
The AC line through the s-bend is going down, as far as I can tell - see attached: it's highlighted in green and comes to an end at the bottom of the image, where it's marked '2'.
I think Jim said the boxes on the left are part of the AC system?
The feed appears to be up the back of the erector, through the white boxes and then back down via the pipe with the s-bend?
Jeff Foust @jeff_foust (https://twitter.com/jeff_foust) · 5 minutes ago (https://twitter.com/jeff_foust/status/773546248339091456)
Here’s a closer look at SpaceX’s SLC-40 from earlier today.
QuoteJeff Foust @jeff_foust (https://twitter.com/jeff_foust) · 5 minutes ago (https://twitter.com/jeff_foust/status/773546248339091456)
Here’s a closer look at SpaceX’s SLC-40 from earlier today.
That's why I'm asking. The pictures we have don't let us track where the conduits all interact at the base of the TEL. Since it's a no-return ventilation system, then you only need one conduit, but if the only -- or best -- place to locate a filter complex is up by stage 2, and you need to run the airstream through it, an up-down-up flow as you suggest might be the best kludge... er, excuse me, compromise, you could come up with to do so.
However, I also recall two statements -- possibly both from Jim -- that seem contradictory. One is that some of the flying debris after the initial flash is likely part of the AC filtering system. The other is that the filtered GN2, and possibly the filtered air intake, for the AC system is provided from a location off the TEL, away from the pad. Which made me think that all of the AC filtering, etc., is done off the TEL, and then led me to wonder what these padded boxes are for...
QuoteJeff Foust @jeff_foust (https://twitter.com/jeff_foust) · 5 minutes ago (https://twitter.com/jeff_foust/status/773546248339091456)
Here’s a closer look at SpaceX’s SLC-40 from earlier today.
QuoteJeff Foust @jeff_foust (https://twitter.com/jeff_foust) · 5 minutes ago (https://twitter.com/jeff_foust/status/773546248339091456)
Here’s a closer look at SpaceX’s SLC-40 from earlier today.
Is there any information to be gleaned from the fact that only one lightning mast is charred? Obviously the "fast fire" did not spread in a circle centered around the vehicle. Am I wrong?
So, the obvious question is -- what the heck is actually inside this set of padded boxes on the TEL?
QuoteJeff Foust @jeff_foust (https://twitter.com/jeff_foust) · 5 minutes ago (https://twitter.com/jeff_foust/status/773546248339091456)
Here’s a closer look at SpaceX’s SLC-40 from earlier today.
Is there any information to be gleaned from the fact that only one lightning mast is charred? Obviously the "fast fire" did not spread in a circle centered around the vehicle. Am I wrong?
Probably only that was the way the wind was blowing ;)
From the latest pictures of the damaged T/E, the only part that appears to be conclusively missing are one or more of the white struts in the section just below the second stage cradle. The loss of these struts seems to be what permitted the cradle to sag forward when the payload fell off. Don't know if these were lost in the initial explosion or secondarily due to the fire. Every other structural part of the T/E seems to be still there, just badly sooted.
QuoteJeff Foust @jeff_foust (https://twitter.com/jeff_foust) · 5 minutes ago (https://twitter.com/jeff_foust/status/773546248339091456)
Here’s a closer look at SpaceX’s SLC-40 from earlier today.
Is there any information to be gleaned from the fact that only one lightning mast is charred? Obviously the "fast fire" did not spread in a circle centered around the vehicle. Am I wrong?
Probably only that was the way the wind was blowing ;)
Can the wind really influence a close to supersonic expansion?
From the latest pictures of the damaged T/E, the only part that appears to be conclusively missing are one or more of the white struts in the section just below the second stage cradle. The loss of these struts seems to be what permitted the cradle to sag forward when the payload fell off. Don't know if these were lost in the initial explosion or secondarily due to the fire. Every other structural part of the T/E seems to be still there, just badly sooted.
The damaged section is, I think, the bit where they extended the height of the erector to adapt it from F9 1.1 to F9 FT.
It has/had several struts I would think of as bottlescrews and several have failed, almost certainly collapsed by the weight of the payload.
As for the condition of the rest of the TEL, bear in mind it has been exposed to massive heat, which may have damaged it beyond repair. It may look as it the lower sections are not warped, but it might take a brave engineer to sign it off as reusable without a lot of very detailed examination
In reality it may be cheaper (and quicker) just to build a new one (okay, the base may well be okay, because that's designed to resist those sort of temperatures) - and I wouldn't be at all surprised if that process hasn't already been started.
Can the wind really influence a close to supersonic expansion?
In reality it may be cheaper (and quicker) just to build a new one (okay, the base may well be okay, because that's designed to resist those sort of temperatures) - and I wouldn't be at all surprised if that process hasn't already been started.
I don't think the base is meant nor designed to withstand an uncontrolled kerosene fire the lasted nearly as long as it did. The heat treatment of the steel, even if it wasn't all melted and sagged out of spec, will be completely ruined. I would not be surprised at all if LC-40 itself has to be rebuilt, possibly including part or all of the concrete hardstand.
Ref Jeff Foust pic posted above...Burned, or just sooted? Maybe it just needs a scrub down like some other items is SpaceX inventory?
The blackened lightning rod tube was on the upwind side, but facing the intense IR heat as the rocket burned down...
It was smoking very heavily when the fireball was at max intensity...
That same tower got smacked near it's base with (I believe) a S1 COPV liberated late in the event... (the lean)
I am surprised how black that one side got... crispy is a good term to use... :o
Thoughts.... this looks like a elongated illumination source, more tall than wide, kinda like you'd see from a shop light.
My tuppeneceworth on this is that we're looking at an explosion of vapour/gases in an oxygen-rich environment outside the vehicle.
Entirely possible that the upper stage tank/tanks was/were ruptured and discharging vapour, which was subsequently ignited by something on the erector.
Around 1/3 second after the first explosion, the upper stage tank(s) started to explode and beyond that point, it's merely narrative rather than anything that would help find a cause.
The 'problem' is that there's no indication of anything awry prior to the first frame showing the explosion.
(Incidentally, I'd agree that the top of the fairing moves slightly to the right around 1/2 second after the initial explosion. Given that the second explosion occurred just before this - which is probably a tank rupturing on the right side - that's unsurprising.)
Some VERY clear, hi res pics of strongback and surrounding area.
Not sure of permissions, so just posting link.
https://imgur.com/a/se8bK
Ref Jeff Foust pic posted above...
The blackened lightning rod tube was on the upwind side, but facing the intense IR heat as the rocket burned down...
It was smoking very heavily when the fireball was at max intensity...
That same tower got smacked near it's base with (I believe) a S1 COPV liberated late in the event... (the lean)
I am surprised how black that one side got... crispy is a good term to use... :o
Some VERY clear, hi res pics of strongback and surrounding area.
Not sure of permissions, so just posting link.
https://imgur.com/a/se8bK
. Also, wasnt this tower on the downwind side (ie, smoke and flame blew into it)?
I'd look it over then scrap it...Some VERY clear, hi res pics of strongback and surrounding area.
Not sure of permissions, so just posting link.
https://imgur.com/a/se8bK
Gotta admit, the damage looks a let less severe than I expected. Still don't know that I'd trust the remains of the T/E based on the heat flux, but overall it's not as bad I would have thought.
Some VERY clear, hi res pics of strongback and surrounding area.
Not sure of permissions, so just posting link.
https://imgur.com/a/se8bK
Hmm, the strongback and all its constituent plumbing looks pretty intact in those pictures (considering what it went though)
So query: in those high-res photos on Imgur, what's the tangle hanging off the end of the T/E?
Yes, but the most damaged area -- where the TEL bent -- is exactly where what I have called the "soft cradle", the small cradle that supports stage 2 right at its common bulkhead, was located -- and it doesn't appear to still be attached to the structure of the TEL.
So query: in those high-res photos on Imgur, what's the tangle hanging off the end of the T/E?
The remains of the umbilicals.
Yes, but the most damaged area -- where the TEL bent -- is exactly where what I have called the "soft cradle", the small cradle that supports stage 2 right at its common bulkhead, was located -- and it doesn't appear to still be attached to the structure of the TEL.
It's still there?
The cradle that supports the stage around the common bulkhead is part of a larger cradle with a second support at the top of the stage at the same height as the 'claw'.
Highlighted in green on the attached.
Will add a 'before' when I can find one...
I wonder...
There's been a lot of speculation that the S-curve AC duct might have been the source of something. This has been counterpointed that it's ONLY an AC duct, and a this point in the countdown is only pushing gasious nitrogen.
However, supercooled LOX can freeze nitrogen and liquify oxygen.
Is there any posibility that the FAIRING got cold enough that the AC airturned liquid and flowed back through the pipe? Where it would get hung up on the S-curve and cause unspecified problems?
Yes, but the most damaged area -- where the TEL bent -- is exactly where what I have called the "soft cradle", the small cradle that supports stage 2 right at its common bulkhead, was located -- and it doesn't appear to still be attached to the structure of the TEL.
It's still there?
The cradle that supports the stage around the common bulkhead is part of a larger cradle with a second support at the top of the stage at the same height as the 'claw'.
Highlighted in green on the attached.
Will add a 'before' when I can find one...
Please do, because yes, I see the structure that connects to the claw-arms (also only one of which is visible in this picture, though the other may be hidden) that support the stack right at the payload fairing adapter, but it seems to be open at the bottom. The only structure I see at the bottom, where the smaller cradle was attached, is the background latticework of the far side of the TEL. I don't see any sign of the small cradle.
Working from this picture:
https://i.imgur.com/cJEQpS1.jpg
here's my attempt. Movable clamp arms are in red, lower cradle structure in green.
Please do, because yes, I see the structure that connects to the claw-arms (also only one of which is visible in this picture, though the other may be hidden) that support the stack right at the payload fairing adapter, but it seems to be open at the bottom. The only structure I see at the bottom, where the smaller cradle was attached, is the background latticework of the far side of the TEL. I don't see any sign of the small cradle.
This is just the type of thing that might not be modeled correctly. They might have modeled a small explosion
Knew I'd seen a better photograph of the cradle: attached, with the frame and the pivot highlighted. The upper supports are at the same height as the claw, which is retracted in the photo.This is the one I posted before, if it's any use to you...
Knew I'd seen a better photograph of the cradle: attached, with the frame and the pivot highlighted. The upper supports are at the same height as the claw.
What I don't see in these post-event images is that actual curved rubber-tipped rest, circled in red in the steadfast image I've again detailed below that we've been looking at for a rough pre-accident TEL illustration.
The TEL bent as a result of the support for the payload and fairing disappearing under them. The payload/fairing pivoted while bending the cradle until it fell. I believe all of the bending happened after the bulk of the rock confettied.
Enjoy, Matthew
The TEL bent as a result of the support for the payload and fairing disappearing under them. The payload/fairing pivoted while bending the cradle until it fell. I believe all of the bending happened after the bulk of the rock confettied.
Enjoy, Matthew
What I don't see in these post-event images is that actual curved rubber-tipped rest, circled in red in the steadfast image I've again detailed below that we've been looking at for a rough pre-accident TEL illustration.
I'm fairly sure that those structures are still in place. The whole assembly is visible (https://i.imgur.com/BdezhQ7.jpg), albeit with poor lighting, in We Report Space's new picture album of SLC-40 (https://imgur.com/a/se8bK).
Why would they model any explosion?
Anyone have a schematic of all the hydraulic lines on the strongback right up to the cradle? I've been trying to locate one....
Just a general comment -- while I don't discount the possibility that a COPV failure could have caused the anomaly, the whole feel of the discussion thus far is like a posse heading out to a hanging. Some people have completely made up their minds, without any access to any data, that the COPVs must be at fault and so now SpaceX is screwed, since their design required the COPVs, used the way they are currently used.
I never liked posses. They end up hanging innocent men a lot of times.
If a COPV is shown to have been the cause of the anomaly, fine, I will accept that. But for now, I will go on record as saying that there are likely other possible causes, and it would not surprise me in the least if this had nothing whatsoever to do with the COPVs.
My own personal opinion is that there was some change to the fueling procedures, to try and support longer hold times after prop loading (as SpaceX announced they were going to be experimenting with on this flight), and the new fueling procedures led to an off-nominal situation that got out of control faster than anyone could react to. But that's my own personal opinion, and it's based on the same lack of facts that we are all working with. I only lean in this direction because, when this happened, I asked myself "What did they do differently this time than what they've done in the past?" and recalled the announced before-mentioned experimentation planned for managing the densified props over longer hold times. You know, just tried to apply some logic to it, and came up with that question and answer.
Beyond that, I don't think it's appropriate to be convicting the COPVs before there is even a trial.
Just a general comment -- while I don't discount the possibility that a COPV failure could have caused the anomaly, the whole feel of the discussion thus far is like a posse heading out to a hanging. Some people have completely made up their minds, without any access to any data, that the COPVs must be at fault and so now SpaceX is screwed, since their design required the COPVs, used the way they are currently used.
I never liked posses. They end up hanging innocent men a lot of times.
If a COPV is shown to have been the cause of the anomaly, fine, I will accept that. But for now, I will go on record as saying that there are likely other possible causes, and it would not surprise me in the least if this had nothing whatsoever to do with the COPVs.
My own personal opinion is that there was some change to the fueling procedures, to try and support longer hold times after prop loading (as SpaceX announced they were going to be experimenting with on this flight), and the new fueling procedures led to an off-nominal situation that got out of control faster than anyone could react to. But that's my own personal opinion, and it's based on the same lack of facts that we are all working with. I only lean in this direction because, when this happened, I asked myself "What did they do differently this time than what they've done in the past?" and recalled the announced before-mentioned experimentation planned for managing the densified props over longer hold times. You know, just tried to apply some logic to it, and came up with that question and answer.
Beyond that, I don't think it's appropriate to be convicting the COPVs before there is even a trial.
Oh come now, I'm not on that posse. Right now I'm looking at the possibility that a hydraulic cylinder blew a gasket spewed a couple of gallons of hydraulic fluid in a second or so, thus creating a FAE. The good news is that if I'm right, the post-event tower photos indicate that the evidence is hanging up there to be found, or not.
I jes don' hold to much with COPV failures.
Before you get too tightly wed to your theory, please remember two things: #1) we don't know what SpaceX uses for hydraulic fluid in the T/E and cradle mechs; #2) there are a number of well-understood hydraulic fluids in common aerospace usage that are not flammable.
There seems to be an awful lot of desperation for it to be anything but the rocket. It's one thing trying to figure out where the explosion occurred, since we can try to work on that with the information available, but another to deduce what caused the overall problem.
There seems to be an awful lot of desperation for it to be anything but the rocket. It's one thing trying to figure out where the explosion occurred, since we can try to work on that with the information available, but another to deduce what caused the overall problem.Reddit user em-power (supposedly ex-SpaceX) says, that the investigation determined that the initial anomaly came from outside the vehicle.
Before you get too tightly wed to your theory, please remember two things: #1) we don't know what SpaceX uses for hydraulic fluid in the T/E and cradle mechs; #2) there are a number of well-understood hydraulic fluids in common aerospace usage that are not flammable.
Well, I was going to put my first born child down as collateral on the bet, but you've dissuaded me. :)
Both of your points are good ones.
If it's not the hydraulics, I'm pretty much out of ideas as to where to look for the initiating event. Maybe I should take off my tin foil hat?
Does that cylinder look heavily corroded to you?
Oh come now, I'm not on that posse. Right now I'm looking at the possibility that a hydraulic cylinder blew a gasket spewed a couple of gallons of hydraulic fluid in a second or so, thus creating a FAE. The good news is that if I'm right, the post-event tower photos indicate that the evidence is hanging up there to be found, or not.
There seems to be an awful lot of desperation for it to be anything but the rocket. It's one thing trying to figure out where the explosion occurred, since we can try to work on that with the information available, but another to deduce what caused the overall problem.
So, absent official data, my question becomes, how do you create an explosion that starts outside of the body of the rocket?
Addendum: *IF* those claw hydraulic cylinders are operated from a remote central pressure system (which presumably also operates the strongback retract); and *IF* that system is routed up the strongback; and *IF* the solenoid valves for the claw cylinders are near them; and *IF* the system is left idle and then pressurised about 8 minutes before hot fire; and *IF* there was a leak 'downstream' of the relevant solenoid; and *IF* that leak was somewhere around the common bulkhead; and *IF* the hydraulic fluid was inflammable - than all you'd need would be an ignition source and you'd have seen exactly what we did see.
There seems to be an awful lot of desperation for it to be anything but the rocket. It's one thing trying to figure out where the explosion occurred, since we can try to work on that with the information available, but another to deduce what caused the overall problem.Reddit user em-power (supposedly ex-SpaceX) says, that the investigation determined that the initial anomaly came from outside the vehicle.
em-power ex-SpaceX 22 points 14 hours ago
take this with a grain of salt, but i just spoke to one of the current spacex employees and according to him, the 'explosion' did originate from outside the rocket. they dont know yet exactly what caused it.
So here is a new one.
What if the rubber pads of the clamps (if they are indeed made of rubber or similar flamable material), became brittle in the cold, with the rubber forming crevasses that became drenched in liquid oxygen (e.g. condensed from air, as it is in contact with the cold wall of the oxygen tank) and then found an ignition source.
So here is a new one.
What if the rubber pads of the clamps (if they are indeed made of rubber or similar flamable material), became brittle in the cold, with the rubber forming crevasses that became drenched in liquid oxygen (e.g. condensed from air, as it is in contact with the cold wall of the oxygen tank) and then found an ignition source.
Liquid oxygen is not going to form on the outside of the tank for two reasons
a. The temperature differential from inside (going from aluminum through ice) is going to be below liquid oxygen formation temperature. The temp difference between LOX boiling and supercooled is less than 25 degree C
B. And if there was a risk of LOX forming, then they would have added insulation.
FWIW heard close to this, firsthand, as well. Be patient.There seems to be an awful lot of desperation for it to be anything but the rocket. It's one thing trying to figure out where the explosion occurred, since we can try to work on that with the information available, but another to deduce what caused the overall problem.Reddit user em-power (supposedly ex-SpaceX) says, that the investigation determined that the initial anomaly came from outside the vehicle.
The exact quote,
Link.... (https://www.reddit.com/r/spacex/comments/50rr9v/falcon_9_amos6_static_fire_anomaly_faq_summary/d7ci0b9)Quoteem-power ex-SpaceX 22 points 14 hours ago
take this with a grain of salt, but i just spoke to one of the current spacex employees and according to him, the 'explosion' did originate from outside the rocket. they dont know yet exactly what caused it.
So here is a new one.
What if the rubber pads of the clamps (if they are indeed made of rubber or similar flamable material), became brittle in the cold, with the rubber forming crevasses that became drenched in liquid oxygen (e.g. condensed from air, as it is in contact with the cold wall of the oxygen tank) and then found an ignition source.
Liquid oxygen is not going to form on the outside of the tank for two reasons
a. The temperature differential from inside (going from aluminum through ice) is going to be below liquid oxygen formation temperature. The temp difference between LOX boiling and supercooled is less than 25 degree C
B. And if there was a risk of LOX forming, then they would have added insulation.
There would be no ice layer where the clamps are, so there could be "wet patches". But yes, it severely limits the amount of oxygen that could condensate.
There seems to be an awful lot of desperation for it to be anything but the rocket. It's one thing trying to figure out where the explosion occurred, since we can try to work on that with the information available, but another to deduce what caused the overall problem.I agree and it bothers me. Spacex and this vehicle are things I care very much about and it's because of that that it bothers me. If you really are a "falcon hugger" let's call it , you should not be trying to find a failure mode that absolves the vehicle, you should be open to all possible failure modes particularly the most likely ones based on available information.
I counted 7 IFs. Let's go to Reddit and claim case closed.
I don't think the hydraulics come from a remote pressure system. Usually there's a small reservoir near the pump and the pump looks like it's just below the main cylinder.
I counted 7 IFs. Let's go to Reddit and claim case closed.
I don't think the hydraulics come from a remote pressure system. Usually there's a small reservoir near the pump and the pump looks like it's just below the main cylinder.
Not sure how good you are on hydraulics?
Yes, you need a pump to generate pressure.
The reservoir is generally a dump for hydraulic fluid at no pressure. The pump creates pressure, the fluid under pressure gets used for moving rams / motors and then the fluid is returned at low pressure to the reservoir, from where the pump picks it up, pressurises it and sends it round the system again.
If the pump is running and there's no demand for the fluid, pressure relief valves will dump the fluid directly back into the reservoir, where the pressure is lost.
In that sort of system, supply is under high pressure, return is effectively at no pressure.
So in this case, how do you generate hydraulic pressure locally?
Potentially a gas cylinder with a diaphragm across to the hydraulic fluid, but I'm not seeing that you could maintain that pressure at a steady level. Also, if it runs out of pressure, you need to lower the erector to recharge the pressure (unless it comes in from elsewhere, in which case just bring the hydraulic fluid in under pressure).
Put a diesel engine on the erector to drive a pump? No on several levels.
Put an electo-hydraulic pump on the erector? Possible, but there's an ignition risk that you'd prefer to avoid.
There has to be a pretty decent hydraulic system already in place to operate the cylinders that retract the erector, so just tap into that with a couple of big hoses that run up the structure. Pretty simple. I'd guess at a diesel motor in a bunker 50-100 yards away?
Basic question: Why does the F9 vent GOX so close to the vehicle and tower?
As I recall, the Shuttle ET vented GOX through a "beanie cap" into a pipe leading meters away. Granted that the ET was covered in foam (and a vent pipe must be free of stray organics!), but high O2 levels seem a risk.
P.S. Any notion of what the recent changes might have been, to allow longer holds with supercooled LOX?
I counted 7 IFs. Let's go to Reddit and claim case closed.
I don't think the hydraulics come from a remote pressure system. Usually there's a small reservoir near the pump and the pump looks like it's just below the main cylinder.
Not sure how good you are on hydraulics?
Yes, you need a pump to generate pressure.
The reservoir is generally a dump for hydraulic fluid at no pressure. The pump creates pressure, the fluid under pressure gets used for moving rams / motors and then the fluid is returned at low pressure to the reservoir, from where the pump picks it up, pressurises it and sends it round the system again.
If the pump is running and there's no demand for the fluid, pressure relief valves will dump the fluid directly back into the reservoir, where the pressure is lost.
In that sort of system, supply is under high pressure, return is effectively at no pressure.
So in this case, how do you generate hydraulic pressure locally?
Potentially a gas cylinder with a diaphragm across to the hydraulic fluid, but I'm not seeing that you could maintain that pressure at a steady level. Also, if it runs out of pressure, you need to lower the erector to recharge the pressure (unless it comes in from elsewhere, in which case just bring the hydraulic fluid in under pressure).
Put a diesel engine on the erector to drive a pump? No on several levels.
Put an electo-hydraulic pump on the erector? Possible, but there's an ignition risk that you'd prefer to avoid.
There has to be a pretty decent hydraulic system already in place to operate the cylinders that retract the erector, so just tap into that with a couple of big hoses that run up the structure. Pretty simple. I'd guess at a diesel motor in a bunker 50-100 yards away?
FWIW heard close to this, firsthand, as well. Be patient.There seems to be an awful lot of desperation for it to be anything but the rocket. It's one thing trying to figure out where the explosion occurred, since we can try to work on that with the information available, but another to deduce what caused the overall problem.Reddit user em-power (supposedly ex-SpaceX) says, that the investigation determined that the initial anomaly came from outside the vehicle.
The exact quote,
Link.... (https://www.reddit.com/r/spacex/comments/50rr9v/falcon_9_amos6_static_fire_anomaly_faq_summary/d7ci0b9)Quoteem-power ex-SpaceX 22 points 14 hours ago
take this with a grain of salt, but i just spoke to one of the current spacex employees and according to him, the 'explosion' did originate from outside the rocket. they dont know yet exactly what caused it.
Thanks, I'm good with those pics. I was more specifically look for locations of hydraulic line couplers areas where one could fail (I agree about 3,000psi as well).Anyone have a schematic of all the hydraulic lines on the strongback right up to the cradle? I've been trying to locate one....
If you're sniffing the same hound that I am, you don't need to trace the lines. This looks like a self contained system.
The cradle uses a hydraulic piston to open & close on a hinge.
It's that black pipe with a silver piston sticking out of it. You can see the extract and extend flow ports at each end of the black pipe. The hoses feed into the pump below and towards the middle of the black pipe.
I "borrowed" these pics from other posters who were pointing out other things and highlighting those.
The first picture shows it extended.
The 2nd picture shows it extracted.
The 3rd picture shows it on the post-event tower, and you can see some of the hydraulic lines from the one on the other side.
I'd be very curious to know if the partially obscured one shows signs of a high-pressure leak.
Also, this looks a lot like a Bosh product, I'm not sure if they monitor the pressure in these. They have a simple job, open or close. They probably operate around 3,000 psi and there is no pre-charge or anything required.
Why hydraulic and not gas actuated.
Why hydraulic and not gas actuated.
Thanks, I'm good with those pics. I was more specifically look for locations of hydraulic line couplers areas where one could fail (I agree about 3,000psi as well).Anyone have a schematic of all the hydraulic lines on the strongback right up to the cradle? I've been trying to locate one....
If you're sniffing the same hound that I am, you don't need to trace the lines. This looks like a self contained system.
The cradle uses a hydraulic piston to open & close on a hinge.
It's that black pipe with a silver piston sticking out of it. You can see the extract and extend flow ports at each end of the black pipe. The hoses feed into the pump below and towards the middle of the black pipe.
I "borrowed" these pics from other posters who were pointing out other things and highlighting those.
The first picture shows it extended.
The 2nd picture shows it extracted.
The 3rd picture shows it on the post-event tower, and you can see some of the hydraulic lines from the one on the other side.
I'd be very curious to know if the partially obscured one shows signs of a high-pressure leak.
Also, this looks a lot like a Bosh product, I'm not sure if they monitor the pressure in these. They have a simple job, open or close. They probably operate around 3,000 psi and there is no pre-charge or anything required.
Just to confirm my theory, I went back to the video posted in the update thread and found my area of interest on the TEL continued to burn on its own well after all other fire had gone out as if under small pressure fed source...(I know it could have been damaged after as well)
https://www.youtube.com/watch?v=Yk4huQ3Iyhg
Thanks Jim for confirming my second thought...Thanks, I'm good with those pics. I was more specifically look for locations of hydraulic line couplers areas where one could fail (I agree about 3,000psi as well).Anyone have a schematic of all the hydraulic lines on the strongback right up to the cradle? I've been trying to locate one....
If you're sniffing the same hound that I am, you don't need to trace the lines. This looks like a self contained system.
The cradle uses a hydraulic piston to open & close on a hinge.
It's that black pipe with a silver piston sticking out of it. You can see the extract and extend flow ports at each end of the black pipe. The hoses feed into the pump below and towards the middle of the black pipe.
I "borrowed" these pics from other posters who were pointing out other things and highlighting those.
The first picture shows it extended.
The 2nd picture shows it extracted.
The 3rd picture shows it on the post-event tower, and you can see some of the hydraulic lines from the one on the other side.
I'd be very curious to know if the partially obscured one shows signs of a high-pressure leak.
Also, this looks a lot like a Bosh product, I'm not sure if they monitor the pressure in these. They have a simple job, open or close. They probably operate around 3,000 psi and there is no pre-charge or anything required.
Just to confirm my theory, I went back to the video posted in the update thread and found my area of interest on the TEL continued to burn on its own well after all other fire had gone out as if under small pressure fed source...(I know it could have been damaged after as well)
That would likely be the prop umbilicals, that contribute to burn like after every launch
There seems to be an awful lot of desperation for it to be anything but the rocket. It's one thing trying to figure out where the explosion occurred, since we can try to work on that with the information available, but another to deduce what caused the overall problem.
Here's why I don't feel desperation.
There's some photo evidence to indicate that the initial event included a fireball that extended beyond the tower to the right, at least 15 feet, towards the camera, at least 20 feet, and not quite to the edge of the F9, < 15 feet. The center of that cylinder is outside of the body of the F9. If the center of that cylinder were inside the F9, then I'd blame the rocket, but it isn't.
So, absent official data, my question becomes, how do you create an explosion that starts outside of the body of the rocket?
Or is that desperation? :)
With a brief bit of thought, given the opportunity I'd prefer to fit a gas-actuated system in an installation like this. Mostly to avoid the potential of hydraulic fluid spraying around.
If this system is gas-actuated, that closes off a potential cause of failure.
Is this part of the system gas-actuated?
There seems to be an awful lot of desperation for it to be anything but the rocket. It's one thing trying to figure out where the explosion occurred, since we can try to work on that with the information available, but another to deduce what caused the overall problem.
Here's why I don't feel desperation.
There's some photo evidence to indicate that the initial event included a fireball that extended beyond the tower to the right, at least 15 feet, towards the camera, at least 20 feet, and not quite to the edge of the F9, < 15 feet. The center of that cylinder is outside of the body of the F9. If the center of that cylinder were inside the F9, then I'd blame the rocket, but it isn't.
So, absent official data, my question becomes, how do you create an explosion that starts outside of the body of the rocket?
Or is that desperation? :)
My issue is that the source of ignition being outside the rocket does not mean the rocket itself is not at fault. There's a lot of stuff that indicates the source is outside, so I'm ok with that. The question I wonder is whether it is a leak in the rocket or the gse
I recently witnessed a coleague with an Aluminium cup filled with liquid Nitrogen at -196°C. A liquid quickly condensed on the outside surface of the cup and dripped onto the table. This liquid was LOX condensed from the surrounding air with a condensation temperature of -186°C. It was not LIN, as the surface was not cold enough to condense Notrogen at -196°C.
On the F9, if air is able to get to the surface of the 2nd stage LOX tank, then the super cooled temperature of the LOX in the tank would cause air (O2 and N2) to condence on the outside surface. LIN would vaporise allot easier with a lower vaporising temperature, leaving a high concentration of LOX/GOX.
Is the LOX tank sealed in air tight insulation? Can air get access to the surface of the aluminium surface of the LOX tank?
A high oxygen environment is one of three incredients for elevated risk of ignition.
I can't even guess what the fuel or the ignition method was.
I recently witnessed a coleague with an Aluminium cup filled with liquid Nitrogen at -196°C. A liquid quickly condensed on the outside surface of the cup and dripped onto the table. This liquid was LOX condensed from the surrounding air with a condensation temperature of -186°C. It was not LIN, as the surface was not cold enough to condense Notrogen at -196°C.
On the F9, if air is able to get to the surface of the 2nd stage LOX tank, then the super cooled temperature of the LOX in the tank would cause air (O2 and N2) to condence on the outside surface. LIN would vaporise allot easier with a lower vaporising temperature, leaving a high concentration of LOX/GOX.
Is the LOX tank sealed in air tight insulation? Can air get access to the surface of the aluminium surface of the LOX tank?
A high oxygen environment is one of three ingredients for elevated risk of ignition.
I can't even guess what the fuel or the ignition method was.
As pointed out much earlier in this thread, the ambient air was high in humidity. As the LOX tank started to be filled and cooled down, the first thing to condense would be water vapor, forming frost then ice. That ice would continue to thicken, completely insulating the O2/N2 in the air from the tank wall long before the Li/Al completely chilled to cryogenic temperatures.
...
Assuming the initial explosion was indeed outside, and assuming SpaceX still doesn't know what it was:
What internally-originated fault can fit those two speculative data points?
Can there be something as simple as a pin-hole RP1 leak from the rocket? (assuming that pressurized RP1 was no longer present in the T/E)
...
Assuming the initial explosion was indeed outside, and assuming SpaceX still doesn't know what it was:
What internally-originated fault can fit those two speculative data points?
Can there be something as simple as a pin-hole RP1 leak from the rocket? (assuming that pressurized RP1 was no longer present in the T/E)
There is no pressurized RP1 in the rocket at T-8 minutes. The RP1 tanks aren't pressed until under 1 minute.
So here is a new one.
What if the rubber pads of the clamps (if they are indeed made of rubber or similar flamable material), became brittle in the cold, with the rubber forming crevasses that became drenched in liquid oxygen (e.g. condensed from air, as it is in contact with the cold wall of the oxygen tank) and then found an ignition source.
Liquid oxygen is not going to form on the outside of the tank for two reasons
a. The temperature differential from inside (going from aluminum through ice) is going to be below liquid oxygen formation temperature. The temp difference between LOX boiling and supercooled is less than 25 degree C
B. And if there was a risk of LOX forming, then they would have added insulation.
I recently witnessed a coleague with an Aluminium cup filled with liquid Nitrogen at -196°C. A liquid quickly condensed on the outside surface of the cup and dripped onto the table. This liquid was LOX condensed from the surrounding air with a condensation temperature of -186°C. It was not LIN, as the surface was not cold enough to condense Notrogen at -196°C.
Now I do see a serious problem with Jims point A.
There simply is no ice layer on the tank to begin with and no other insulation we'd have heard of. It would take some time for the ice layer to form and the tank would be uninsulated in the meantime. Usually, that cannot possibly be a problem. The LOX is filled in at boiling temperature anyway and there is never any chance at all to condense oxygen from the air.
With subcooled oxygen in the tank, there is a short window of opportunity for oxygen to condense - prior to any ice layer forming on the tank and insulating it.
Now I do see a serious problem with Jims point A.
There simply is no ice layer on the tank to begin with and no other insulation we'd have heard of. It would take some time for the ice layer to form and the tank would be uninsulated in the meantime. Usually, that cannot possibly be a problem. The LOX is filled in at boiling temperature anyway and there is never any chance at all to condense oxygen from the air.
With subcooled oxygen in the tank, there is a short window of opportunity for oxygen to condense - prior to any ice layer forming on the tank and insulating it.
The cup analogy is really not applicable. There is big difference in thermal mass. Ice should be forming during the chill down. But then again, the loading time is less than 30 minutes
But also, I should have said:
And if there was a risk of LOX forming, then they SHOULD have added insulation. My point is that they would have analyzed this. When liquid air forms on the outside and drains away, it is putting more heat into the tank
Notice that it's not enough to have hydraulic rams controlling the extension of the strongback top. You have to actuate these rams to relieve any axial shear force between the cradle and rocket. So you need some kind of servo loop. If the servo loop pauses you harm the rocket. So the root cause here could be a momentary loss of hydraulic pressure to the strongback temperature compensating hydraulics during chilldown of any of the propellant tanks.
Again, though, we know that LOX load was in process; am I right in thinking that LOX and RP-1 load simultaneously? Was RP-1 being loaded at the time of the anomaly, or just LOX?
One final thing: a jet of kerosene heading towards the camera would be hard to see. It could develop for a frame or two before you'd notice.
What would the consequences be if tanks of something other than GN2 were either delivered or incorrectly connected before the flush?
Basic question: Why does the F9 vent GOX so close to the vehicle and tower?The reason NASA used the "beanie cap" was that NASA did not want any ice accumulating on the surface of the ET, and subsequently shedding during flight and damaging the HRSI insulation tiles on the belly of the orbiters.
As I recall, the Shuttle ET vented GOX through a "beanie cap" into a pipe leading meters away. Granted that the ET was covered in foam (and a vent pipe must be free of stray organics!), but high O2 levels seem a risk.
P.S. Any notion of what the recent changes might have been, to allow longer holds with supercooled LOX?
I went through all the frames one by one (in the 60 fps video). Here's a quick list of what I found:
• I reconstructed the origin path of 3 individual pieces flying around and they appear to have come from the
same 1mx1m area, about 1-2 meter below the common bulkhead (about 1-2 meters below the origin of the
lens flare, visible in the second frame)
• I agree that they look like aluminum tank skin: one of them in particular reflects back the light of the fire in
one of the frames.
• I reconstructed the various lens flares in the video. I don't think they pinpoint the origin of the detonation -
they are simply pointing to the geometric middle of the visible detonation plume, i.e. the lens flare origin
doesn't have a true physical meaning. (The trajectories of the ejecta are more reliable and seem to point
slightly below the lens flare center.)
• I annotated the apparent movement of the nose cone and found that it's not real movement but the optical
illusion created by a burning plume rising on the left side of the rocket - this illuminates part of the fairing
that creates the appearance of it leaning towards the strongback. (Until the fairing is covered by the plume.)
• The aperture of the camera appears to be unchanged for the first couple of frames - this can be verified
from looking at the visible brightness of constant light sources, such as lighting.
• Based on this the 'average illumination' of the fire can be seen on the bottom right spherical LOX tank, as
the fire gets reflected and shrunk. That point of light is the illumination: it clearly suggests a bright initial
detonation followed by a fire that is ramping up.
• (Later on the camera auto-shrinks its aperture as the fireball expands and its heat increases.)
• Interestingly the frames themselves are showing a second peak in illumination, but this cannot be seen in
the reflection on the big spherical LOX tank. This is the 5th frame of the explosion in the video: this is the
only frame that is showing two lens flares. It is possible that the plume of the first explosion is shadowing
the second one in the direction of the big spherical LOX tank, but the air is still clear towards the camera. So
I believe there are 3 events altogether: the first detonation was very quick, the second one lasted 3-5
frames, and the third one (structural disintegration) was the big fire everyone sees when watching the
video.
• The shadows in the frame are all very interesting: for example in the first frame the shadow of the left side
grid fin suggests that the first detonation happened over a volume that extended well beyond the rocket's
diameter, in the direction of the camera. (This appears to support fuel/air mixture scenarios.)
• The sharp shadow at the lower part of the rocket suggest either that the detonation also occurred within the
strong-arm's volume, and the structure possibly shadowed the flash - or another possibility is that the water
fog created by the first stage LOX tank is so thick that it stop the flash from penetrating further down.
• The illumination of the fairing suggests a detonation volume that must also be extending away from the
rocket in the rocket's direction.
• The illumination of the strongback's middle region also gives an idea about how far the detonation plume
must extend away from the strongback.
• Ejecta analysis looks interesting too: much later in the video still unburnt LOX can be seen ejecting to the
right, without having any fuel to burn - and turning into a white cloud as it freezes out moisture from the air.
(It's cold LOX because it keeps going to the right, not rising up like hot gases do.)
They appear to me to possibly be tank parts. They are curved, and appear to be venting a gas (or steaming
if they are very cold.) One can be seen going past the payload, then deflecting off the TE and continuing up
with a good bit of energy. It can be followed all the way to the ground. Another piece can be seen on the left
side. I found three pieces altogether. (I also found a fourth piece of shrapnel and reconstructed its
trajectory, which pointed to a weird place - only to realize that it was a bird.)
I was going to download the video this weekend and do some analysis because I thought I was going to be home bound due to the hurricane, but it blew past, so I didn't have the chance. The thing I was most interested in is working from the original 60 fps video. Everyone seems to be using stills from 30 fps versions and missing intermediate frames.
Here's my conclusion based on that analysis:
• I think the video supports an air/fuel detonation scenario: I just don't see how a COPV failure cold have
reached all those places so quickly and created all those specific shadows - without also ejecting LOX
through the strongback in the first frame. Also, LOX alone is not enough to create an initial large-volume
detonation - fuel is also needed.
• So I think the initially detonated mixture was necessarily fuel-rich: which supports a fuel leak (RP-1 or
hydrazine) as the root cause, not a LOX leak.
• The pressure wave of the air/fuel detonation pushed in the S2 tank skin at around the common bulkhead,
which sheared the tank skin like a knife, rupturing both the LOX tank and the RP-1 tank.
• The fuel-rich detonation died down after frame 1, because it consumed all oxygen from the air in the volume
of detonation. The volume was still fuel-rich at this point
• As the LOX exited from the now ruptured LOX tank it created the quick bright flash in frame 5 as it
consumed all quick sources of fuel not consumed by the initial detonation. This kind of very bright flash is
typical of LOX rupture: complete combustion of everything fuel.
• This flash too dies down quickly, because now all sources of fuel are gone.
• But now both the LOX and the RP-1 tanks are ruptured catastrophically, and the LOX is falling down into the
RP-1 tank - which creates the real big explosion and the subsequent avalanche of deflagration.
I think the rightward and slightly downward motion of the fairing is a significant find. That's actually quite a bit of motion, maybe 0.6 meters in about 1 second, or 1.2 m/s^2 acceleration at the tip, about 20 meters above the site of the initial flash.
I think this is consistent with the right wall of stage 2 rupturing while the wall was under significant axial compression, not axial tension.
When the stage is at the correct pressure, the walls are under axial tension. So it seems to me that while the payload is moving, the ullage is well below nominal pressure, and my guess is that it is in the kerosene ullage, not the LOX ullage, because the flash happens around the level of the kerosene ullage. Note that I'm not suggesting the ullage is below atmospheric pressure, but rather that the pressure is too low to support the nearly 100 tonnes of payload and LOX above it. Supporting that load requires around 93 kPa above ambient.
The fairing motion happens after the flash, so I think that during a fair bit of the initial flamey bits, the stage is below nominal pressure. To me, that says it's not an internal pressure vessel failure, which would have caused overpressure and pushed the payload to the left after a right wall rupture. To me that's a big deal because until I saw that video I was pretty sure it was a pressure vessel problem.
So now my favorite theory is that there was a problem in the cradle that holds stage 2, perhaps during erection or chilldown. My guess is that stage 2 got stressed in a way it can't tolerate. This stress caused a slight buckle in the skin that wasn't noticed but reduced it's ultimate tensile strength. Pressurizing the stage caused a rupture at the previously-buckled point, at a point low enough that kerosene and not ullage gas under a nominal ullage pressure was ejected forcibly from the tank. I don't know what the ignition source was, but it must have been immediately proximate to the kerosene jet. The tearing aluminum-lithium metal might have done it.
I also had some thoughts about that cradle holding stage 2. It's got a difficult job. While the stage is horizontal it's not too bad, the cradle just balances the load between the upper and lower clamps. But when the stage rotates to vertical, the cradle must react to horizontal wind loads without reacting to the shrinkage of the rocket when cooled. So there is some bearing that lets the cradle go up and down, but that system has to support the weight of the portion of the strongback that is rising and falling with the upper stage. Otherwise, that weight is going to go into the rocket, but it's off center, so it's going to produce a torque. That torque is going to produce a strong force on the lower clamp in the direction from the strongback to the rocket. That force would tend to buckle the skin of the rocket inwards.
Notice that it's not enough to have hydraulic rams controlling the extension of the strongback top. You have to actuate these rams to relieve any axial shear force between the cradle and rocket. So you need some kind of servo loop. If the servo loop pauses you harm the rocket. So the root cause here could be a momentary loss of hydraulic pressure to the strongback temperature compensating hydraulics during chilldown of any of the propellant tanks.
One final thing: a jet of kerosene heading towards the camera would be hard to see. It could develop for a frame or two before you'd notice.
Hydrazine is not feasible. It would have gone off in the fairing
Hydrazine is not feasible. It would have gone off in the fairing
Nice to see your personal and professional experience jibes with my engineering intuition.
So assuming an external fuel/air explosive event, any ideas how enough fuel could or would rise the 10' or so from the the apparently-unpressurized RP1 umbilicals? If RP1 loading was complete but the tank not yet at flight pressure, how does that happen? Could a check valve in the RP1 QD have failed, combined with a hole in the umbilical causing a vertical spray or mist up in the clouds of venting O2 gas?
I just don't get the mechanism yet.
Hydrazine is not feasible. It would have gone off in the fairing
Hydrazine is not feasible. It would have gone off in the fairing
Nice to see your personal and professional experience jibes with my engineering intuition.
So assuming an external fuel/air explosive event, any ideas how enough fuel could or would rise the 10' or so from the the apparently-unpressurized RP1 umbilicals? If RP1 loading was complete but the tank not yet at flight pressure, how does that happen? Could a check valve in the RP1 QD have failed, combined with a hole in the umbilical causing a vertical spray or mist up in the clouds of venting O2 gas?
I just don't get the mechanism yet.
I'm struggling with the fact that I've read that Kerosene vapors are heavier than air.
Hydrazine is not feasible. It would have gone off in the fairing
Apologies if this is a bit of an odd question, but do we know the specific hydrazine compound that Amos-6 utilized? Monoprop is implied, so that points to hydrazine hydrate (I believe).
Hydrazine is not feasible. It would have gone off in the fairing
Apologies if this is a bit of an odd question, but do we know the specific hydrazine compound that Amos-6 utilized? Monoprop is implied, so that points to hydrazine hydrate (I believe).
hydrazine hydrate is not a propellant. Mono prop would be pure hydrazine. But some biprops use it too. The other is MMH.
Hydrazine is not feasible. It would have gone off in the fairing
Apologies if this is a bit of an odd question, but do we know the specific hydrazine compound that Amos-6 utilized? Monoprop is implied, so that points to hydrazine hydrate (I believe).
hydrazine hydrate is not a propellant. Mono prop would be pure hydrazine. But some biprops use it too. The other is MMH.
Much appreciated. Do you have any idea what prop Amos-6 was to use?
FWIW, here are some edits of the We Report Space member's photos of the TE. Did my best to improve visibility.
FWIW, here are some edits of the We Report Space member's photos of the TE. Did my best to improve visibility.
So looking at the first of the two photos you've attached, I see that one of the umbilicals looks like it's superficially intact, hanging straight down. If you trace it up, it seems as if it's still attached to the large rectangular structure on the T/E in the center of the frame. At the bottom, however, there is a second, more slender umbilical that looks like it's not attached at the top. The photo isn't clear but it looks as if the large rectangular structure has a blackened hole in the center, where the second umbilical might have been attached.
Thoughts?
While viewing the video I noticed that prior to 15 seconds of the anomaly (explosion) vapor is venting rather rapidly from the back (away from the rocket) of the T/E. 15 seconds prior to the anomaly it stops and vapor starts venting from the second stage. This seems to correlate to an event on the countdown at T-10:00 of 'stage two venting for LOX fast fill'. I know that Musk tweeted that the anomaly occurred at approximately T-8 minutes, but perhaps that was just an approximation. If the anomaly occurred at T-9:45 the closest event on the countdown is
TEA-TEB ignition setup. I know what TEA-TEB is and why it is on the rocket, but no idea what 'ignition setup' means.
and it was a static fire of the first stage, there would be no TEB/TEA Ops
...
The diameter of the F9 is 12 feet. Using that as a rough yardstick, a supersonic expansion would have to be more than one F9 diameter per frame. It isn't.
...
Fireball diameter is actually TWICE the diameter of the F9 there.
One odd thing, that puzzles me, is the leftmost shape of the initial fireball. I have in mind those 3 "tongues". This implies, that at least this part of the explosion front should probably be subsonic and parts of it's propagation should have been obstructed in some ways.
I should point out, that close to sonic wave propagation is complex and there may be transitions in both ways - from detonation to deflagration and the other way.
When there was FAE, then it may have started out as deflagration, then progressed temporarily as detonation in low supersonic and then outgassed (after it run out of oxygen in FAE mixture) as subsonic cloud.
When there was COPV, then I do not see how this could have started as subsonic event.
I would argue that such a leak would, without an ignition source, have been able to exist without any obvous sign, starting well before the explosion.Hydrazine is not feasible. It would have gone off in the fairing
Nice to see your personal and professional experience jibes with my engineering intuition.
So assuming an external fuel/air explosive event, any ideas how enough fuel could or would rise the 10' or so from the the apparently-unpressurized RP1 umbilicals? If RP1 loading was complete but the tank not yet at flight pressure, how does that happen? Could a check valve in the RP1 QD have failed, combined with a hole in the umbilical causing a vertical spray or mist up in the clouds of venting O2 gas?
I just don't get the mechanism yet.
I'm struggling with the fact that I've read that Kerosene vapors are heavier than air.
IF a fuel-air explosive event occurred outside the vehicle, it would probably not be kerosene vapor but atomized droplets (essentially an aerosol), as might be sprayed under pressure through a very tiny leak. Not sure I underdetsand how that could happen at that point in the countdown if such an event did in fact occur involving kerosene.
While viewing the video I noticed that prior to 15 seconds of the anomaly (explosion) vapor is venting rather rapidly from the back (away from the rocket) of the T/E. 15 seconds prior to the anomaly it stops and vapor starts venting from the second stage.
I think the rightward and slightly downward motion of the fairing is a significant find. That's actually quite a bit of motion, maybe 0.6 meters in about 1 second, or 1.2 m/s^2 acceleration at the tip, about 20 meters above the site of the initial flash.
I think this is consistent with the right wall of stage 2 rupturing while the wall was under significant axial compression, not axial tension.
When the stage is at the correct pressure, the walls are under axial tension. So it seems to me that while the payload is moving, the ullage is well below nominal pressure, and my guess is that it is in the kerosene ullage, not the LOX ullage, because the flash happens around the level of the kerosene ullage. Note that I'm not suggesting the ullage is below atmospheric pressure, but rather that the pressure is too low to support the nearly 100 tonnes of payload and LOX above it. Supporting that load requires around 93 kPa above ambient.
The fairing motion happens after the flash, so I think that during a fair bit of the initial flamey bits, the stage is below nominal pressure. To me, that says it's not an internal pressure vessel failure, which would have caused overpressure and pushed the payload to the left after a right wall rupture. To me that's a big deal because until I saw that video I was pretty sure it was a pressure vessel problem.
So now my favorite theory is that there was a problem in the cradle that holds stage 2, perhaps during erection or chilldown. My guess is that stage 2 got stressed in a way it can't tolerate. This stress caused a slight buckle in the skin that wasn't noticed but reduced it's ultimate tensile strength. Pressurizing the stage caused a rupture at the previously-buckled point, at a point low enough that kerosene and not ullage gas under a nominal ullage pressure was ejected forcibly from the tank. I don't know what the ignition source was, but it must have been immediately proximate to the kerosene jet. The tearing aluminum-lithium metal might have done it.
I also had some thoughts about that cradle holding stage 2. It's got a difficult job. While the stage is horizontal it's not too bad, the cradle just balances the load between the upper and lower clamps. But when the stage rotates to vertical, the cradle must react to horizontal wind loads without reacting to the shrinkage of the rocket when cooled. So there is some bearing that lets the cradle go up and down, but that system has to support the weight of the portion of the strongback that is rising and falling with the upper stage. Otherwise, that weight is going to go into the rocket, but it's off center, so it's going to produce a torque. That torque is going to produce a strong force on the lower clamp in the direction from the strongback to the rocket. That force would tend to buckle the skin of the rocket inwards.
Notice that it's not enough to have hydraulic rams controlling the extension of the strongback top. You have to actuate these rams to relieve any axial shear force between the cradle and rocket. So you need some kind of servo loop. If the servo loop pauses you harm the rocket. So the root cause here could be a momentary loss of hydraulic pressure to the strongback temperature compensating hydraulics during chilldown of any of the propellant tanks.
One final thing: a jet of kerosene heading towards the camera would be hard to see. It could develop for a frame or two before you'd notice.
Is it correct that the thrust-vectoring on the M-Vac uses pressurised RP fuel during flight?
If so, is there a separate ground-side pressurised supply (and return) for the required fluids for the pre-launch test of this system?
Is this another potential fuel source for the fireball?
This system does not need to be pressurized before engines start running. Simply because before that, there's no thrust to vector :-)
This system does not need to be pressurized before engines start running. Simply because before that, there's no thrust to vector :-)
And what about MVac TVC checks prior to flight, known to have caused a scrub on at least one occasion?
Yes the FTS is exonerated. It is impossible for a stray signal to activate it. In the SAFE mode, there is a physical block between the initiator and chargeBesides, as my former co-worker with knowledge of explosive characteristics pointed out: an inadvertant FTS detonation would not look anything like what was witnessed.
Yes the FTS is exonerated. It is impossible for a stray signal to activate it. In the SAFE mode, there is a physical block between the initiator and chargeBesides, as my former co-worker with knowledge of explosive characteristics pointed out: an inadvertant FTS detonation would not look anything like what was witnessed.
As FTS on F9FT has detcord installed (actually 2 detcords) along the tank, the actual activation of it should look like this:
Attached you can see a subtraction between Frame 0 and Frame 1. Essentially the differences.
and the claim is this happened<---doesn't say who said it.
Feynman's rubber ring, but supercooled?
As FTS on F9FT has detcord installed (actually 2 detcords) along the tank, the actual activation of it should look like this:
Source for this? I was under the impression that it was actually several shaped charges at discrete points.
5) More to the point, this has taken out craft before - most notably the X-1A and X-1D, whose tanks were contaminated by a chemical used in the manufacture of their gaskets. And the stage in which they went off? Why, pressurization, of course ;)
5) More to the point, this has taken out craft before - most notably the X-1A and X-1D, whose tanks were contaminated by a chemical used in the manufacture of their gaskets. And the stage in which they went off? Why, pressurization, of course ;)
That had nothing to do with combustion of aluminum. The LOX tanks in the X-craft were sealed with Ulmer leather gaskets, containing tricresyl phosphate, which became explosive when exposed to LOX. In fact, the propellant tanks were made of stainless steel. When the gaskets were compressed between the tank flanges after assembly, the sealing compound containing TCP oozed out. Any mechanical shock was enough to cause it to detonate.
As FTS on F9FT has detcord installed (actually 2 detcords) along the tank, the actual activation of it should look like this:
Source for this? I was under the impression that it was actually several shaped charges at discrete points.
I would argue that such a leak would, without an ignition source, have been able to exist without any obvous sign, starting well before the explosion.Hydrazine is not feasible. It would have gone off in the fairing
Nice to see your personal and professional experience jibes with my engineering intuition.
So assuming an external fuel/air explosive event, any ideas how enough fuel could or would rise the 10' or so from the the apparently-unpressurized RP1 umbilicals? If RP1 loading was complete but the tank not yet at flight pressure, how does that happen? Could a check valve in the RP1 QD have failed, combined with a hole in the umbilical causing a vertical spray or mist up in the clouds of venting O2 gas?
I just don't get the mechanism yet.
I'm struggling with the fact that I've read that Kerosene vapors are heavier than air.
IF a fuel-air explosive event occurred outside the vehicle, it would probably not be kerosene vapor but atomized droplets (essentially an aerosol), as might be sprayed under pressure through a very tiny leak. Not sure I underdetsand how that could happen at that point in the countdown if such an event did in fact occur involving kerosene.
T-8:00, then, would be when some kind of ignition source was introduced to this already existing fuel-air mixture.
I think the rightward and slightly downward motion of the fairing is a significant find. That's actually quite a bit of motion, maybe 0.6 meters in about 1 second, or 1.2 m/s^2 acceleration at the tip, about 20 meters above the site of the initial flash.
I think this is consistent with the right wall of stage 2 rupturing while the wall was under significant axial compression, not axial tension.
When the stage is at the correct pressure, the walls are under axial tension. So it seems to me that while the payload is moving, the ullage is well below nominal pressure, and my guess is that it is in the kerosene ullage, not the LOX ullage, because the flash happens around the level of the kerosene ullage. Note that I'm not suggesting the ullage is below atmospheric pressure, but rather that the pressure is too low to support the nearly 100 tonnes of payload and LOX above it. Supporting that load requires around 93 kPa above ambient.
The fairing motion happens after the flash, so I think that during a fair bit of the initial flamey bits, the stage is below nominal pressure. To me, that says it's not an internal pressure vessel failure, which would have caused overpressure and pushed the payload to the left after a right wall rupture. To me that's a big deal because until I saw that video I was pretty sure it was a pressure vessel problem.
So now my favorite theory is that there was a problem in the cradle that holds stage 2, perhaps during erection or chilldown. My guess is that stage 2 got stressed in a way it can't tolerate. This stress caused a slight buckle in the skin that wasn't noticed but reduced it's ultimate tensile strength. Pressurizing the stage caused a rupture at the previously-buckled point, at a point low enough that kerosene and not ullage gas under a nominal ullage pressure was ejected forcibly from the tank. I don't know what the ignition source was, but it must have been immediately proximate to the kerosene jet. The tearing aluminum-lithium metal might have done it.
...
This system does not need to be pressurized before engines start running. Simply because before that, there's no thrust to vector :-)
And what about MVac TVC checks prior to flight, known to have caused a scrub on at least one occasion?
Good point :-) Then it means, that the hydraulics line should be pressurized, there should be hydraulic accumulator for keeping pressure and there should be pressurized RP-1 supply. Now we are talking.
...
How? The tank was not pressurized at the time
Ok, armchair detectives, besides the obvious (LOX tank, lightning towers, engines), what can be effectively RULED OUT of the root cause at this point?
For example, clearly the bottom half of the rocket did not explode, what does that rule out?
I would argue that such a leak would, without an ignition source, have been able to exist without any obvous sign, starting well before the explosion.Hydrazine is not feasible. It would have gone off in the fairing
Nice to see your personal and professional experience jibes with my engineering intuition.
So assuming an external fuel/air explosive event, any ideas how enough fuel could or would rise the 10' or so from the the apparently-unpressurized RP1 umbilicals? If RP1 loading was complete but the tank not yet at flight pressure, how does that happen? Could a check valve in the RP1 QD have failed, combined with a hole in the umbilical causing a vertical spray or mist up in the clouds of venting O2 gas?
I just don't get the mechanism yet.
I'm struggling with the fact that I've read that Kerosene vapors are heavier than air.
IF a fuel-air explosive event occurred outside the vehicle, it would probably not be kerosene vapor but atomized droplets (essentially an aerosol), as might be sprayed under pressure through a very tiny leak. Not sure I underdetsand how that could happen at that point in the countdown if such an event did in fact occur involving kerosene.
T-8:00, then, would be when some kind of ignition source was introduced to this already existing fuel-air mixture.
How? The tank was not pressurized at the time
Silence of SpaceX is deafening... :o
I would argue that such a leak would, without an ignition source, have been able to exist without any obvous sign, starting well before the explosion.Hydrazine is not feasible. It would have gone off in the fairing
Nice to see your personal and professional experience jibes with my engineering intuition.
So assuming an external fuel/air explosive event, any ideas how enough fuel could or would rise the 10' or so from the the apparently-unpressurized RP1 umbilicals? If RP1 loading was complete but the tank not yet at flight pressure, how does that happen? Could a check valve in the RP1 QD have failed, combined with a hole in the umbilical causing a vertical spray or mist up in the clouds of venting O2 gas?
I just don't get the mechanism yet.
I'm struggling with the fact that I've read that Kerosene vapors are heavier than air.
IF a fuel-air explosive event occurred outside the vehicle, it would probably not be kerosene vapor but atomized droplets (essentially an aerosol), as might be sprayed under pressure through a very tiny leak. Not sure I underdetsand how that could happen at that point in the countdown if such an event did in fact occur involving kerosene.
T-8:00, then, would be when some kind of ignition source was introduced to this already existing fuel-air mixture.
How? The tank was not pressurized at the time
If the RP1 tank is full, it's pressurized at least by gravity (head pressure).
Perhaps the best thing we can do is to start eliminating, based on lowest probability, what it couldn't be. Because, to be honest, I've been following this thread with great interest (as many no doubt are) and all the suggested scenarios seem to get MythBusted pretty easily.
So I'll start - again, a list of what it couldn't be and why it couldn't be.
- payload prop leaking: because fairing was intact when it toppled.
- FTS: because the system is mechanically isolated prior to arming, and it wasn't armed at time of event.
- pressurized RP-1 leak from S2 tank creating aerosol leading to FAE: because tank wasn't pressurized at time of event.
If the RP1 tank is full, it's pressurized at least by gravity (head pressure).
Not nearly enough to produce a mist required for FAE to form.
T-0:09:30 M1D Trim Valve Cycling
T-0:09:15 Stage 1 Helium Topping
T-0:07:45 MVac Fuel Trim Valve Setup
anybody know what these events are? 9:30 and 7:45?
Silence of SpaceX is deafening... :o
Ok, armchair detectives, besides the obvious (LOX tank, lightning towers, engines), what can be effectively RULED OUT of the root cause at this point?
Hydraulic fitting... ;DOk, armchair detectives, besides the obvious (LOX tank, lightning towers, engines), what can be effectively RULED OUT of the root cause at this point?
For me the biggest things to be ruled out are all those that we would be considering if this failure had happened in flight, as with CRS-7. Vibration, aerodynamic stress, g-forces, bending moments. No engines running, M-Vac wasn't in chilldown. We're looking for something that happened very fast, very quietly without any apparent outside mechanical force.
Silence of SpaceX is deafening... :o
Fairly certain the last thing on SpaceX's mind right now is appeasing forums of conspiracy theorists and arm chair rocket scientists with half baked info. This isn't a game, and truly in the big picture we don't even register on their radar. I expect nothing less and nothing more than them to keep their heads down, find the problem and when ready communicate the minimum they need to reassure their customers/potential customers and save face where they can.
Jobs, businesses, and potential industries are in the balance. I hope they take all the time they need, and am happy they see twitter isn't high on the list of "customers" they need to be focused on.
Attached you can see a subtraction between Frame 0 and Frame 1. Essentially the differences.
Great work! Attached is an enhanced version. You can see the far off spherical LOX tank is quite illuminated, along with the top of a lightning tower. The bird that is passing by is seen as a bright spot near the middle tower. The gases that are moving or illuminated around the rocket can also be seen more clearly.
And how soon we forget...CRS-7 failure took (a mere) 3 weeks for SpaceX to release preliminary findings, and in the launch vehicle world even that is unusually fast. Other failure investigations (Taurus, Pegasus XL) have taken much longer. Expecting SpaceX to say anything this soon is unrealistic, unless the root cause is blindingly obvious, which it usually isn't.That's a good benchmark given the explosion was high up and out to sea, whereas here it's (literally) on their doorstep with lots of direct video and telemetry and a fairly tight timeframe to analyze.
Obviously there would be cameras and sound, but would they have anything like a spectral analyser monitoring it or anything like that?
Obviously there would be cameras and sound, but would they have anything like a spectral analyser monitoring it or anything like that?
There would be no need for such devices.
Obviously there would be cameras and sound, but would they have anything like a spectral analyser monitoring it or anything like that?
There would be no need for such devices.
...LOx and Aluminum facts...
...LOx and Aluminum facts...
My question about this scenario is "OK, so unoxidized aluminum oxidizes rapidly in LOx, but what event caused the aluminum to be exposed? What caused the tank to be so severely bent that exposed enough raw aluminum to cause a runaway reaction?"
It's putting the cart before the horse. A successful launch hinges on them being able to load LOx into an aluminum tank; I'd assume they know the risks and the rocket passed their checks before being rolled out to the pad. If something messed up the LOx tank that much after raising it on the pad and the rocket didn't explode, they'd still have to have an investigation and delay a bunch of launches.
Ok, armchair detectives, besides the obvious (LOX tank, lightning towers, engines), what can be effectively RULED OUT of the root cause at this point?
For example, clearly the bottom half of the rocket did not explode, what does that rule out?
Well clearly it rules out everything in the first stage, and all the associated umbilicals to the first stage. But we knew that as soon as we'd seen video. Read the thread. The suspects are all well-talked out at this point.
Obviously there would be cameras and sound, but would they have anything like a spectral analyser monitoring it or anything like that?
There would be no need for such devices.
Why do you say that? Do you not think knowing what is combusting in the initial phases of the explosion would be useful data?
Not nearly enough to produce a mist required for FAE to form.
My main speculative sources for pressurized RP-1 are hydraulic accumulators in MVac hydraulic scheme. Anyone knows wehere they are located? Only thing is that when MVac hydraulics are pressurized by spinning dry turbine during chilldown process, then the pressure is non-nominal to say the least. I do not know, how the hydraulics are pressurized, while turbine is not running.
Perhaps it is pressurized by filling the accumulators first to certain level and then injecting pressurized N2 to their gas bubbles.
Yes, I've read the hundreds of COPV/not COPV messages. And while people have narrowed to some favorites, it's also interesting to box in the problem with what it cannot be. Like, can the strongback be eliminated? Or parts of it? It seems the fairing and the payload are eliminated as well. Does that eliminate the systems connected to them? What systems are monitored and would shut down the static fire if tripped -- aren't those also eliminated? Like fuel pressure in the LOX pumps/hoses/tanks?
My main speculative sources for pressurized RP-1 are hydraulic accumulators in MVac hydraulic scheme. Anyone knows wehere they are located? Only thing is that when MVac hydraulics are pressurized by spinning dry turbine during chilldown process, then the pressure is non-nominal to say the least. I do not know, how the hydraulics are pressurized, while turbine is not running.
Rocket ScienceWelcome to the forum! Great and informative first post for the "video sleuths" on here, thanks! :)
Most video editors have a reverse play connected with either the Speed or Duration effect. In Adobe Premiere the effect is Crtl+R. You can also speed up or slow down the action within the reversal effect. Make a copy of the original video in your editor timeline; Ctrl+C, Crtl+V. Select the copy and apply the reversal effect, Crtl+R. Set the Duration or Speed. This works in Premiere and Pinnacle. Instructions may also apply to Vegas. It's been a few years since I last used Vegas.
Musk has been unusually silent on Twitter the past week. I wonder if Shotwell told him he needs to stop leaning forward on incidents like this?
Can? I would say, want to share.... I read the silence as they don't have anything definite yet.
I don't think anyone can tell Elon what to do! :) I'm sure they will provide an update when they have something they can share.
Musk has been unusually silent on Twitter the past week. I wonder if Shotwell told him he needs to stop leaning forward on incidents like this?
I don't think anyone can tell Elon what to do! :) I'm sure they will provide an update when they have something they can share.
Musk has been unusually silent on Twitter the past week. I wonder if Shotwell told him he needs to stop leaning forward on incidents like this?
Yes, I've read the hundreds of COPV/not COPV messages. And while people have narrowed to some favorites, it's also interesting to box in the problem with what it cannot be. Like, can the strongback be eliminated? Or parts of it? It seems the fairing and the payload are eliminated as well. Does that eliminate the systems connected to them? What systems are monitored and would shut down the static fire if tripped -- aren't those also eliminated? Like fuel pressure in the LOX pumps/hoses/tanks?
I doubt the strongback can be eliminated, in the same way the vehicle can't be eliminated.
Both have the potential to have provided the fuel and/or the oxidiser the caused the explosion.
Elon's comment "originated around the upper stage oxygen tank" can be read as "originated in the approximate area of the upper stage oxygen tank" or "originated outside the upper stage oxygen tank". It doesn't particularly help.
Thus, the equipment on the strongback must remain as much of a suspect as the vehicle is.
You would think the pad has multiple microphones for triangulation.
Anybody know?
You would think the pad has multiple microphones for triangulation.
Anybody know?
What would that provide that video doesn't?
Musk has been unusually silent on Twitter the past week. I wonder if Shotwell told him he needs to stop leaning forward on incidents like this?
Musk has been unusually silent on Twitter the past week. I wonder if Shotwell told him he needs to stop leaning forward on incidents like this?
He was also silent after the CRS-7 accident. So can we now say that he is "usually silent" after accidents, since this has been the case both times?
Can we also stop condescending, like he's a high school student who doesn't know when to shut up? SpaceX is in the middle of an extremely sensitive accident investigation, and he'll keep quiet about the details until they have a root cause nailed down, and have briefed customers, NASA and Air Force. Just like last time.
You would think the pad has multiple microphones for triangulation.
Anybody know?
What would that provide that video doesn't?
3 time synchronized microphones being recorded at 20khz could localize the bang within about half an inch.
sound travels at 1125.33 feet/second
1125.33/20000 = 0.05 feet
1 microphone places it on a sphere
2 places it on a circle
3 places it at one of two points
You would think the pad has multiple microphones for triangulation.
Anybody know?
OK, gang... using my geologic engineering background, i believe i have a plausible explanation of the *ploink* and rumble on the vid. YES is DOES COME FROM THE JUNKYARD!, but the explosion and subsequent fireball ARE to blame. Since the S1 is attached to the pad/ground, it transmits the pressure wave directly to the ground. This is why it registered on seismic equipment. since pressure waves travel much faster through the ground than in the compressible air, the transient noises in the video are caused by the explosion. The shock traveling through the ground will arrive to the microphone location before the sound traveling in the air. This shockwave/impulse caused something in the yard to tilt,rub,bang or rattle . Initial explosion shock arrival IS the *ploink* and fireball/collapse of the stack is the rattle. That should put everything to bed... what do you think Chris?
this will be for pressure or P-Wave impulses
since the coastal area of CCAFS is mostly unconsolidated sediment & sand, one can use 1000 meters/sec as velocity.
Here's the study from 2011 by University of Florida regarding seismic energy propagation in FLA
http://www.dot.state.fl.us/research-center/Completed_Proj/Summary_SMO/FDOT_BDK75_977-01_rpt.pdf
I'll let you have fun with the maths
for all the experts here :
Is it possible to make spectroscopic analysis from the Video of the AMOS-6 fire to deduct which material was
involved in the initial fast fire ? we all assumed that the white color is oxygen or over saturation of the camera
but maybe more sensitive analysis can discover more ?
Musk has been unusually silent on Twitter the past week. I wonder if Shotwell told him he needs to stop leaning forward on incidents like this?
for all the experts here :
Is it possible to make spectroscopic analysis from the Video of the AMOS-6 fire to deduct which material was
involved in the initial fast fire ? we all assumed that the white color is oxygen or over saturation of the camera
but maybe more sensitive analysis can discover more ?
Just curious regarding all the discussion about SpaceX having their own video of the failure: Is that an assumption or an established fact?
Just curious regarding all the discussion about SpaceX having their own video of the failure: Is that an assumption or an established fact?
The fact is they have 2 Falcon 9's lost to 2nd stage failures. Whether or not these are common, we do not know.
Just curious regarding all the discussion about SpaceX having their own video of the failure: Is that an assumption or an established fact?They would need a full spectrum camera for analysis which is not sop...
They would need a full spectrum camera for analysis which is not sop...Small nit, but "hyper spectral" is the correct industry term. Camera's that have true hyper spectral sampling in all bands at the same time do not usually have the highest frame rate and resolution. They usually build up the images over time either with a slit and grating or narrow bandpass filtering (which can be filters or a double subtractive grating combo).
Nits are good, but what I've used in the lab is this type...They would need a full spectrum camera for analysis which is not sop...Small nit, but "hyper spectral" is the correct industry term. Camera's that have true hyper spectral sampling in all bands at the same time do not usually have the highest frame rate and resolution. They usually build up the images over time either with a slit and grating or narrow bandpass filtering (which can be filters or a double subtractive grating combo).
Nice, a pushbroom, aka slit and grating. 1 cube every 7 seconds or so... So getting back to why this isn't standard SOP for watching a vehicle, in 7 seconds the event had already progressed well past the point of data being interesting.Nits are good, but what I've used in the lab is this type...They would need a full spectrum camera for analysis which is not sop...Small nit, but "hyper spectral" is the correct industry term. Camera's that have true hyper spectral sampling in all bands at the same time do not usually have the highest frame rate and resolution. They usually build up the images over time either with a slit and grating or narrow bandpass filtering (which can be filters or a double subtractive grating combo).
http://www.spectralcameras.com/files/SisuCHEMA_brochure.pdf
Just curious regarding all the discussion about SpaceX having their own video of the failure: Is that an assumption or an established fact?
Just curious regarding all the discussion about SpaceX having their own video of the failure: Is that an assumption or an established fact?They would need a full spectrum camera for analysis which is not sop...
...
Still curious if they had the internal LOX tank camera turned on and what did it see...
...
Still curious if they had the internal LOX tank camera turned on and what did it see...
Eee... Considering, that the internals of the LOX tank do not have good natural lighting conditions, I would bet, that only thing you see from this video is following:
1. Everything is normal
2. Everything is oversaturated
3. Everything is black as camera went offline
Yes, they could do a camera conversion..Just curious regarding all the discussion about SpaceX having their own video of the failure: Is that an assumption or an established fact?They would need a full spectrum camera for analysis which is not sop...
You could do a lot with far simpler gear than that.
Anyone brought attention to the weld between bottom of the LOX tank and the tube running inside RP tank?I did, a zillion pages back... ;D Slight correction my weld comment was more about the circumference of the tank, so your area is new as far as I know...
What if LOX would slowly drip there. Assuming there is 10cm of free space left at the top of the RP tank after fueling, that is 0.6 cubic meters of GOX, or ~0.6 liters (0.5kg) of LOX.
LOX falling from the small hole could even turn a bit of RP solid and make a small pool of LOX on the top...
As there is a vent from the top of RP tank to atmosphere (can be seen during end of normal static fires videos, when it is opened after engines stop running to release pressure from RP tank), this LOX boiling in RP tank might get unnoticed...
~1kg of mixed propellants (not sure about ignition source though) might be enough to rip the tank skin apart.
...
Still curious if they had the internal LOX tank camera turned on and what did it see...
Eee... Considering, that the internals of the LOX tank do not have good natural lighting conditions, I would bet, that only thing you see from this video is following:
1. Everything is normal
2. Everything is oversaturated
3. Everything is black as camera went offline
I go so far as to say the inside of the LOX tank has absolutely no natural lighting 8) But the artificial lighting for the camera might be enough to catch some anomalous events before the explosion.
Just curious regarding all the discussion about SpaceX having their own video of the failure: Is that an assumption or an established fact?They would need a full spectrum camera for analysis which is not sop...
Just curious regarding all the discussion about SpaceX having their own video of the failure: Is that an assumption or an established fact?They would need a full spectrum camera for analysis which is not sop...
SOP is to have cameras that record events, not cameras that are to record catastrophic events. You want to get indications if something is odd on the pad right now. The cameras aren't there, and weren't assigned specific functions, based on the possibility that a rocket might explode, so we might want spectral analysis. They are there to, for example, visually confirm that a valve has closed, or that the TEL has retracted the correct amount, before going on to the next item of the count. Especially if a sensor fails and you can't tell if the TEL has retracted from the sensors on it, for example.
Cameras are for monitoring current events, not for reconstructing catastrophic failures. You don't go in assuming catastrophic failures...
While today, we no longer put checkerboard patterns on rockets, since they don't usually spin out of control, the cameras are there for the same reason.
I don't get what you are saying to me Doug. My only comment was about having a highly specialized camera was not now part of norm video ops outside of the IR they use in addition to the standard video tracking camera...Just curious regarding all the discussion about SpaceX having their own video of the failure: Is that an assumption or an established fact?They would need a full spectrum camera for analysis which is not sop...
SOP is to have cameras that record events, not cameras that are to record catastrophic events. You want to get indications if something is odd on the pad right now. The cameras aren't there, and weren't assigned specific functions, based on the possibility that a rocket might explode, so we might want spectral analysis. They are there to, for example, visually confirm that a valve has closed, or that the TEL has retracted the correct amount, before going on to the next item of the count. Especially if a sensor fails and you can't tell if the TEL has retracted from the sensors on it, for example.
Cameras are for monitoring current events, not for reconstructing catastrophic failures. You don't go in assuming catastrophic failures...
While today, we no longer put checkerboard patterns on rockets, since they don't usually spin out of control, the cameras are there for the same reason.
No, it is because we can get reliable telemetry to get the roll rate data. It has nothing to do with reliability.
While today, we no longer put checkerboard patterns on rockets, since they don't usually spin out of control, the cameras are there for the same reason.
No, it is because we can get reliable telemetry to get the roll rate data. It has nothing to do with reliability.
LOL, I have to watch my phrasing around you. :)
I didn't mean to suggest that roll rate was the reason for cameras, but that globally for all launches, there's a 5.8% failure rate, and cameras are a good means albeit not the only of determining why.
source: http://space.stackexchange.com/questions/8566/what-is-the-success-failure-ratio-of-space-bound-rockets
Question for Jim, PadRat, others who actually work on the hardware:
How does SpaceX know that the consumables that they receive from 3rd parties are not contaminated, and that all of the pumps and lines on the pad are clear of foreign matter besides what is meant to flow through them?
That sounds like a great way to convince yourself that JPEG compression artifacts represent real events.
Jim,
One theory that came up earlier was a pinhole leak in a hydraulics system leading to a fuel-air explosion. But that would seem to be a hazard for any LOX-based launch vehicle. Do you know if there are non-flammable hydraulic fluids, and is it typical for rocket companies to use those non-flammable hydraulic fluids in their launch site hydraulics (ie stuff that is going to be operating near venting GOX)?
I did a quick bit of googling, and it does look like there's a whole class of Flame Resistant Hydraulic Fluids, that are meant for use specifically in areas where they're operating near flame or other hazards, but do you know if it's standard practice to use those types of hydraulic fluid? Do you know if SpaceX does?
Just curious. Because if the hydraulic fluid they were using wasn't flammable, I'm back to wondering where they would've had a pressurized fuel source that could've created the Fuel Air Explosion that others are suggesting was the cause of the incident.
~Jon
I don't get what you are saying to me Doug. My only comment was about having a highly specialized camera was not now part of norm video ops outside of the IR they use in addition to the standard video tracking camera...Just curious regarding all the discussion about SpaceX having their own video of the failure: Is that an assumption or an established fact?They would need a full spectrum camera for analysis which is not sop...
SOP is to have cameras that record events, not cameras that are to record catastrophic events. You want to get indications if something is odd on the pad right now. The cameras aren't there, and weren't assigned specific functions, based on the possibility that a rocket might explode, so we might want spectral analysis. They are there to, for example, visually confirm that a valve has closed, or that the TEL has retracted the correct amount, before going on to the next item of the count. Especially if a sensor fails and you can't tell if the TEL has retracted from the sensors on it, for example.
Cameras are for monitoring current events, not for reconstructing catastrophic failures. You don't go in assuming catastrophic failures...
Tory Bruno weighs in on SpaceX's pad failure...
http://fortune.com/2016/09/08/spacex-grounded/
“It typically takes nine to 12 months for people to return to flight. That’s what the history is,” Tory Bruno, chief executive of United Launch Alliance, told Reuters.
All I was trying to say is that, under normal circumstances, the reason for having cameras is for monitoring items on the rocket and on the pad to visually verify status of various items. Their purpose is not so much to gather data to be used in accident investigations, it is for the moment-to-moment verification of things you want to verify before you give your "go" to proceed with the count.
Tory Bruno weighs in on SpaceX's pad failure...
http://fortune.com/2016/09/08/spacex-grounded/
“It typically takes nine to 12 months for people to return to flight. That’s what the history is,” Tory Bruno, chief executive of United Launch Alliance, told Reuters.
Tory Bruno weighs in on SpaceX's pad failure...
http://fortune.com/2016/09/08/spacex-grounded/
“It typically takes nine to 12 months for people to return to flight. That’s what the history is,” Tory Bruno, chief executive of United Launch Alliance, told Reuters.
So I wonder how he explains the RTF from CRS-7 taking 6-months.
Russia just brushes the debris off the launch pad and launches again. Practically.
https://www.youtube.com/watch?v=7nL10C7FSbE
Shows that a direct flame does not ignite Jet-A, it needs to be an aerosol
What kind of external analytical tools would normally be monitoring this? Obviously there would be cameras and sound, but would they have anything like a spectral analyser monitoring it or anything like that?
Tory Bruno weighs in on SpaceX's pad failure...
http://fortune.com/2016/09/08/spacex-grounded/
“It typically takes nine to 12 months for people to return to flight. That’s what the history is,” Tory Bruno, chief executive of United Launch Alliance, told Reuters.
So I wonder how he explains the RTF from CRS-7 taking 6-months.
As I said above, I think you're reading too much into it. I think he was trying to say politely that he had no better idea than anyone else who's not at SpaceX, but here's what it has typically been in the past. Not "it can't go any faster than this" or "it's definitely going to take them a long time to figure this out", but more a "how on earth am I supposed to answer that question--here's what it's taken historically, but beyond that your guess is as good as mine".
~Jon
Anyone brought attention to the weld between bottom of the LOX tank and the tube running inside RP tank?
Still working on the Falcon fireball investigation. Turning out to be the most difficult and complex failure we have ever had in 14 years.
Important to note that this happened during a routine filling operation. Engines were not on and there was no apparent heat source.
Support & advice from @NASA, @FAA, @AFPAA & others much appreciated. Please email any recordings of the event to [email protected].
Particularly trying to understand the quieter bang sound a few seconds before the fireball goes off. May come from rocket or something else.
Just out of curiosity,
I have heard SpaceX uses GoPro cameras for video feeds. Is this true?
Does anyone know where the GoPro cameras are located on the rocket?
Are they stock standard or modified?
Cheers,
Peter
Elon:Could the explosion been caused by a short circuit somewhere within the GSE? Short circuits can easily be powerful enough to cause a large explosion.
"Still working on the Falcon fireball investigation. Important to note that this happened during a routine filling operation. Engines were not on and there was no apparent heat source. Turning out to be the most difficult and complex failure we have ever had in 14 years.. Support & advice from @NASA, @FAA, @AFPAA & others much appreciated. Please email any recordings of the event to [email protected]. Particularly trying to understand the quieter bang sound a few seconds before the fireball goes off. May come from rocket or something else."
That sure sounds to me like they can't figure out the source of the fire. Based on other leaks it seems the know the fire started externally. They likely know the venting LOX ignited (hence trying to find the source of heat), but from what?
Could the explosion been caused by a short circuit somewhere within the GSE? Short circuits can easily be powerful enough to cause a large explosion.
Well, that's worrisome. I mean, if a week later they still apparently don't have a good candidate for the cause...
Could the explosion been caused by a short circuit somewhere within the GSE? Short circuits can easily be powerful enough to cause a large explosion.
I had earlier speculated this was the cause, but that's what he's saying, they haven't found a short, or an arc, or a spark, or anything else that could cause (what I think they believe to be) ignition of the venting LOX.
He further said they hadn't ruled out a drone or other impact. It's kind of crazy they're even thinking that direction in my opinion.
Might I ask where he mentioned external impacts?
Just out of curiosity,
I have heard SpaceX uses GoPro cameras for video feeds. Is this true?
Does anyone know where the GoPro cameras are located on the rocket?
Are they stock standard or modified?
Cheers,
Peter
I've read somewhere that they started to make their own cameras a few years back, but before that I believe they used GoPro's yea
Could there be the possibility that Amos-6 was sabotaged in some way? Some people on Twitter seem to think that foul play may have been at hand.Could the explosion been caused by a short circuit somewhere within the GSE? Short circuits can easily be powerful enough to cause a large explosion.
I had earlier speculated this was the cause, but that's what he's saying, they haven't found a short, or an arc, or a spark, or anything else that could cause (what I think they believe to be) ignition of the venting LOX.
He further said they hadn't ruled out a drone or other impact. It's kind of crazy they're even thinking that direction in my opinion.
Well, that's worrisome. I mean, if a week later they still apparently don't have a good candidate for the cause...
With the thousands of telemetry channels and and video feeds they have, the fact that they not only don't have a likely candidate, but they don't have any candidate means at the very least the failure occurred in a place thought impossible to occur, and thus was unmonitored. Or it was external to the rocket and GSE and thus impossible to predict.
Could there be the possibility that Amos-6 was sabotaged in some way? Some people on Twitter seem to think that foul play may have been at hand.
Every incident has people claiming:Could there be the possibility that Amos-6 was sabotaged in some way? Some people on Twitter seem to think that foul play may have been at hand.Could the explosion been caused by a short circuit somewhere within the GSE? Short circuits can easily be powerful enough to cause a large explosion.
I had earlier speculated this was the cause, but that's what he's saying, they haven't found a short, or an arc, or a spark, or anything else that could cause (what I think they believe to be) ignition of the venting LOX.
He further said they hadn't ruled out a drone or other impact. It's kind of crazy they're even thinking that direction in my opinion.
Could there be the possibility that Amos-6 was sabotaged in some way? Some people on Twitter seem to think that foul play may have been at hand.
Any time Israel is involved there will always be that train of thought - sometimes rightfully - but in this particular case I personally feel it's far more likely that if there is sabotage involved, it's targeted towards SpaceX rather than Spacecom.
Sounds like they worked through the fault tree and found nothing wrong and are left with more questions then answers.
As they intimately know their own rocket, I guess they particularly could not figure out what would cause ignition from any of the possible elements in that part of the rocket/erector.
An failing tank, compartment or COPV would likely be visible before any form of ignition, would it not? Also such an event would/should clearly be visible in several of the 3000 telemetry channels.
Also, as a rule, it is generally useful to invoke Occam's Razor in the context of most things analytical. In the sense of launch vehicle failures, this means avoiding the invocation of external actors before all other possible routes of failure have been ruled out.
Any chance we have sound of that "quieter bang" Elon mentioned?
Jim,
One theory that came up earlier was a pinhole leak in a hydraulics system leading to a fuel-air explosion. But that would seem to be a hazard for any LOX-based launch vehicle. Do you know if there are non-flammable hydraulic fluids, and is it typical for rocket companies to use those non-flammable hydraulic fluids in their launch site hydraulics (ie stuff that is going to be operating near venting GOX)?
Any chance we have sound of that "quieter bang" Elon mentioned?
Attached below, two sounds, at 6 and 8 seconds. Unless he means a sound from a recording other than the USLR one.
2. A pinhole leak in a LOX hose would physically blow it apart, so assuming they can find the umbilicals that should be a relatively easy one to rule in or out.
Also, as a rule, it is generally useful to invoke Occam's Razor in the context of most things analytical. In the sense of launch vehicle failures, this means avoiding the invocation of external actors before all other possible routes of failure have been ruled out.
Of course, but it appears in this case they haven't found a cause in the rocket or GSE, which means they have to look externally.
Since Musk commented on the external impact theory, I'll give some thoughts. Based on my own armchair analysis of the video, I don't think the purported videos showing impact are true. Even for pro racing drones, they are moving too fast.
My next train of thought would be a bird shorting something. But they would have on video a bird in the area, even if not the short itself, I have to assume they have enough cameras around the area of ignition to see a bird around there.
Then for fun let's think about guns. Elon actually tweeted they heard a sound before the explosion they can't source. Let's say someone pulled off the road with a .50 cal. There are numerous spots within 2 miles, well within range of the gun. The first bang heard could in theory be the sound barrier being broken by the bullet.
Finally, there is the laser threat. Unlike the .50 cal, this would have to be corporate sabotage or nation state, but it is in theory possible.
The thing about a bullet is that it would almost certainly be supersonic at the point of impact, meaning that the report would only be heard after (and likely several seconds after for a shot from a mile or more out).
Any chance we have sound of that "quieter bang" Elon mentioned?
Attached below, two sounds, at 6 and 8 seconds. Unless he means a sound from a recording other than the USLR one.
This is a good point, esp with regards to be (admittedly unlikely) .50 cal theory. If the first bang was recorded near the cameras away from the pad, then a gun is in play. If it was recorded on the pad, that likely eliminates a gun as a potential source.
Elon:
Support & advice from @NASA, @FAA, @AFPAA & others much appreciated.
What failure modes would have been immediately obvious from telemetry data and can those be ruled out after Elons tweets (COPV, LOX condensing from air,...)?
Elon:
Support & advice from @NASA, @FAA, @AFPAA & others much appreciated.
Will we see @FBI and @DHSgov in this list?
Any chance we have sound of that "quieter bang" Elon mentioned?
Attached below, two sounds, at 6 and 8 seconds. Unless he means a sound from a recording other than the USLR one.
This is a good point, esp with regards to be (admittedly unlikely) .50 cal theory. If the first bang was recorded near the cameras away from the pad, then a gun is in play. If it was recorded on the pad, that likely eliminates a gun as a potential source.
Neither of the noises on that recording sound like any kind of gun I've ever heard.
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So, I'm going to go way the heck off the deep end here and speculate obnoxiously on the bang Musk mentioned; he's looking for recordings, and one possible use for those is triangulation. Just as one would do for, say, a gunshot. Could a rifle bullet (hitting S2 or the payload or the TLE) do what we've seen?
>
Well, now that the bullet theory has been brought up, you don't need someone on land lurking nearby. Might as well go full conspiracy: Do they close off boating traffic offshore for a static test? If not, someone should check if any Russian trawlers or small pleasure craft were "fishing" just offshore. Just joking, but at this point...
Also this reply, make of it what you want.QuoteAJ @ashwin7002 34m34 minutes ago
@elonmusk @NASA @faa @AFPAA there are some videos on YouTube claiming something hit the rocket. Any reality there?QuoteElon Musk Verified account
@elonmusk:
@ashwin7002 @NASA @faa @AFPAA We have not ruled that out.
Any chance we have sound of that "quieter bang" Elon mentioned?
Attached below, two sounds, at 6 and 8 seconds. Unless he means a sound from a recording other than the USLR one.
This is a good point, esp with regards to be (admittedly unlikely) .50 cal theory. If the first bang was recorded near the cameras away from the pad, then a gun is in play. If it was recorded on the pad, that likely eliminates a gun as a potential source.
Neither of the noises on that recording sound like any kind of gun I've ever heard.
Didn't someone on here yesterday posit that the first thump could've been sound transmitted through the ground, which would reach the microphone quicker than the pressure wave through the air?
Also this reply, make of it what you want.This might just fit with a rumour coming from within SpaceX (days ago, but I refrained from posting because rumours are usually just that: rumours) that substantial parts of the fault tree focusing on F9 itself have been closed with parts focusing on GSE and external sources (meaning not the GSE and not the vehicle) still wide open.QuoteAJ @ashwin7002 34m34 minutes ago
@elonmusk @NASA @faa @AFPAA there are some videos on YouTube claiming something hit the rocket. Any reality there?QuoteElon Musk Verified account
@elonmusk:
@ashwin7002 @NASA @faa @AFPAA We have not ruled that out.
Well, now that the bullet theory has been brought up, you don't need someone on land lurking nearby. Might as well go full conspiracy: Do they close off boating traffic offshore for a static test? If not, someone should check if any Russian trawlers or small pleasure craft were "fishing" just offshore. Just joking, but at this point...
Why would they need to use a firearm?
How would a single shot with a gun disperse enough fuel AND oxidizer quickly enough to create such a big, immediate fireball? Wouldn't that disperse more of one fuel fist?
Didn't someone on here yesterday posit that the first thump could've been sound transmitted through the ground, which would reach the microphone quicker than the pressure wave through the air?
No. Not even quarry blasts have this kind of audible ground "thump," although you may hear a rumble which is essentially dirt grinding against each other. Just because the ground vibrates doesn't mean it will transmit that back into the air as a sound wave. There are a large number of raypaths and different vibrational modes, so no. If I were SpaceX, I would be looking for nearby seismic data. If it were a source coupled to the ground, it would show up as a trace from a reasonable distance.
Can anyone suggest a frame averaging freeware download that permits image enhancement within a static image between selected frame #s?
How would a single shot with a gun disperse enough fuel AND oxidizer quickly enough to create such a big, immediate fireball? Wouldn't that disperse more of one fuel fist?
Or, one could ask the complement to that question: where and when would you shoot to intentionally blow up a rocket?
I dont know if mod action is required for this, but could someone interested in the sabotage/shooting hypothesis please start a new thread? The hypothesis cant be ruled out easily but I suggest this because the sabotage stuff has so much potential for all sorts of conspiracy theories that have no place in a technical analysis of this failure. Also, I dont do it myself because I dont want my name attached to it. Thank you.
Any chance we have sound of that "quieter bang" Elon mentioned?
Attached below, two sounds, at 6 and 8 seconds. Unless he means a sound from a recording other than the USLR one.
This is a good point, esp with regards to be (admittedly unlikely) .50 cal theory. If the first bang was recorded near the cameras away from the pad, then a gun is in play. If it was recorded on the pad, that likely eliminates a gun as a potential source.
Neither of the noises on that recording sound like any kind of gun I've ever heard.
Didn't someone on here yesterday posit that the first thump could've been sound transmitted through the ground, which would reach the microphone quicker than the pressure wave through the air?
No. Not even quarry blasts have this kind of audible ground "thump," although you may hear a rumble which is essentially dirt grinding against each other. Just because the ground vibrates doesn't mean it will transmit that back into the air as a sound wave. There are a large number of raypaths and different vibrational modes, so no. If I were SpaceX, I would be looking for nearby seismic data. If it were a source coupled to the ground, it would show up as a trace from a reasonable distance.
The problem with some "device" on the erector is that requires either an inside job, or someone evading detection while sneaking onto a secure military base. With those scenarios, there is a possibility of capture and exposure. A boat offshore remains anonymous and can just slip away. Who would like to get their commercial launch business back? Who is hacking all sorts of sensitive US servers? Sad to say, but this stuff just writes itself. Which is why this sort of cause will be almost impossible to confirm.SpaceX is no threat to state actors who can just wait for SpaceX to pave the path so they can copy the system if it proves economic.
Didn't someone on here yesterday posit that the first thump could've been sound transmitted through the ground, which would reach the microphone quicker than the pressure wave through the air?
No. Not even quarry blasts have this kind of audible ground "thump," although you may hear a rumble which is essentially dirt grinding against each other. Just because the ground vibrates doesn't mean it will transmit that back into the air as a sound wave. There are a large number of raypaths and different vibrational modes, so no. If I were SpaceX, I would be looking for nearby seismic data. If it were a source coupled to the ground, it would show up as a trace from a reasonable distance.
Could it make a difference that the ground water table at the cape is very near the surface? The primary underground acoustic transmission could be by that water. If the water table vibrates at an audible frequency, why would the vibration not be transmitted to the air, even though attenuated considerably at the ground/air interface?
if the video was shot in a junk yard then the ground vibration would just have to vibrate a large metal object.
EDIT: I was kayaking on a river in portsmouth nh and they were driving piles. I got to a distance away where I could here the pile driver and also here the one before resonating on a buoy. The vibration traveling faster in the water was inaudible until it reached a large metal buoy which was making the sound.
I dont know if mod action is required for this, but could someone interested in the sabotage/shooting hypothesis please start a new thread? The hypothesis cant be ruled out easily but I suggest this because the sabotage stuff has so much potential for all sorts of conspiracy theories that have no place in a technical analysis of this failure. Also, I dont do it myself because I dont want my name attached to it. Thank you.
Jim,
One theory that came up earlier was a pinhole leak in a hydraulics system leading to a fuel-air explosion. But that would seem to be a hazard for any LOX-based launch vehicle. Do you know if there are non-flammable hydraulic fluids, and is it typical for rocket companies to use those non-flammable hydraulic fluids in their launch site hydraulics (ie stuff that is going to be operating near venting GOX)?
I did a quick bit of googling, and it does look like there's a whole class of Flame Resistant Hydraulic Fluids, that are meant for use specifically in areas where they're operating near flame or other hazards, but do you know if it's standard practice to use those types of hydraulic fluid? Do you know if SpaceX does?
Just curious. Because if the hydraulic fluid they were using wasn't flammable, I'm back to wondering where they would've had a pressurized fuel source that could've created the Fuel Air Explosion that others are suggesting was the cause of the incident.
~Jon
Elon:
"Still working on the Falcon fireball investigation. Important to note that this happened during a routine filling operation. Engines were not on and there was no apparent heat source. Turning out to be the most difficult and complex failure we have ever had in 14 years.. Support & advice from @NASA, @FAA, @AFPAA & others much appreciated. Please email any recordings of the event to [email protected]. Particularly trying to understand the quieter bang sound a few seconds before the fireball goes off. May come from rocket or something else."
That sure sounds to me like they can't figure out the source of the fire. Based on other leaks it seems the know the fire started externally. They likely know the venting LOX ignited (hence trying to find the source of heat), but from what?
Does anyone know when, during the countdown, the cameras are turned on?
Has anybody done something as simple as hold up a diffraction grating in front of a cell phone and done a video of firecracker going off?
If the initial flash is small enough you might get useful spectra from it. Probably better at night.
You could then introduce various metals into the explosive and see the signature.
Does anyone know when, during the countdown, the cameras are turned on?
They are always on
Does anyone know when, during the countdown, the cameras are turned on?
They are always on
But are they recording?
If they had multiple recordings they would not be wondering if the noises heard before the initial explosion were coming from around the rocket or not. If they already had good coverage they wouldn't be asking for the public to send in amateur video taken from miles away.
if the video was shot in a junk yard then the ground vibration would just have to vibrate a large metal object.
EDIT: I was kayaking on a river in portsmouth nh and they were driving piles. I got to a distance away where I could here the pile driver and also here the one before resonating on a buoy. The vibration traveling faster in the water was inaudible until it reached a large metal buoy which was making the sound.
Water conducts pressure waves very well, but couples poorly to air. As for ground, you have to have a very precise set of conditions to get a drum or whatever to do the same. Ground transmission is made up of pressure waves, shear waves, ground roll and a whole bunch of other little modes as well.
Does anyone know when, during the countdown, the cameras are turned on?
They are always on
But are they recording?
If they had multiple recordings they would not be wondering if the noises heard before the initial explosion were coming from around the rocket or not. If they already had good coverage they wouldn't be asking for the public to send in amateur video taken from miles away.
Maybe they're hoping some of the amateur video will include footage of the surrounding area, beyond the perimeter of the launch facility.
Possible. Problem is that's going to be people filming family on the beach, etc. Very few people video static fires (and probably only the guys with the video we've seen). SpaceX teams have their own footage, but clearly they want more. And the other Cape assets - of which there are many - are not used for testing....only for launches.
Does anyone know when, during the countdown, the cameras are turned on?
They are always on
But are they recording?
Does anyone know when, during the countdown, the cameras are turned on?
They are always on
But are they recording?
If they had multiple recordings they would not be wondering if the noises heard before the initial explosion were coming from around the rocket or not. If they already had good coverage they wouldn't be asking for the public to send in amateur video taken from miles away.
They don't record sound
I dont know if mod action is required for this, but could someone interested in the sabotage/shooting hypothesis please start a new thread? The hypothesis cant be ruled out easily but I suggest this because the sabotage stuff has so much potential for all sorts of conspiracy theories that have no place in a technical analysis of this failure. Also, I dont do it myself because I dont want my name attached to it. Thank you.
Update thread for pure updates.
This discussion thread for technical and other discussion, from the rocket (which is not receiving any blame right now), the TE and GSE.
Wild Theories (which are NOT being ruled out, per Elon's comments, so don't complain about people asking about it....) here:
https://forum.nasaspaceflight.com/index.php?topic=41119.0
They don't record sound
So: Other recordings needed to triangulate that "quieter bang sound a few seconds before the fireball goes off"?
They don't record sound
So: Other recordings needed to triangulate that "quieter bang sound a few seconds before the fireball goes off"?
Surely there must be dozens of security cameras recording sound scattered around the Cape?
I don't think musk was referring to the us launch recording sound before explosion. Unless they really don't have any better sound recordings?
Any object hitting the vehicle would be picked up by the same high speed accelerometers that were able to triangulate the strut failing.
They don't record sound
So: Other recordings needed to triangulate that "quieter bang sound a few seconds before the fireball goes off"?
Falcon 9 FT is known for producing scary looking barfs of oxygen through its relief valve. I do not remember the same thing happening with previous (not supercooled LOX) version. Any chance this may be somehow related to what happened?
I don't think musk was referring to the us launch recording sound before explosion. Unless they really don't have any better sound recordings?
Has anybody done the computation for sound in rock versus sound in air to see if it lines up with the thunk sound in the us launch video? The time delay for sound was what 12s. How much before the explosion was the thunk heard?
I don't think musk was referring to the us launch recording sound before explosion. Unless they really don't have any better sound recordings?
Has anybody done the computation for sound in rock versus sound in air to see if it lines up with the thunk sound in the us launch video? The time delay for sound was what 12s. How much before the explosion was the thunk heard?
Thunk happened ~5.25 seconds before main explosion started.
Falcon 9 FT is known for producing scary looking barfs of oxygen through its relief valve. I do not remember the same thing happening with previous (not supercooled LOX) version. Any chance this may be somehow related to what happened?
I don't think musk was referring to the us launch recording sound before explosion. Unless they really don't have any better sound recordings?
Has anybody done the computation for sound in rock versus sound in air to see if it lines up with the thunk sound in the us launch video? The time delay for sound was what 12s. How much before the explosion was the thunk heard?
Thunk happened ~5.25 seconds before main explosion started.
That gives a wave propagation speed of about 700 m/s. About twice the speed of propagation in air, about half the speed of propagation in water. Not sure about propagation speed in swampy dirt. Unless that "pre-thunk" can be corroborated by a recording from a different location, I'm not convinced it's not merely a coincidence.
Has anybody done the computation for sound in rock versus sound in air to see if it lines up with the thunk sound in the us launch video? The time delay for sound was what 12s. How much before the explosion was the thunk heard?
Has anybody done the computation for sound in rock versus sound in air to see if it lines up with the thunk sound in the us launch video? The time delay for sound was what 12s. How much before the explosion was the thunk heard?
ok I just relistened to the video.
1:12 fireball
1:18 pop sound
1:24 big boom
Do I have those times right?
I'm sure it is upthread somewhere.
If these are the sounds them I get:
340m/s *12s = 4080 meters
4080/6000m/s=.68 seconds
in other words the p-wave should arrive about half a second after the visual explosion.
I used 6000m/s for p-wave in linestone.
Falcon 9 FT is known for producing scary looking barfs of oxygen through its relief valve. I do not remember the same thing happening with previous (not supercooled LOX) version. Any chance this may be somehow related to what happened?
This venting isn't unique, as shown by my photo from the Thaicom-8 launch on May 27. My recollection was that I took this photo at about T-4 minutes.
Discussed here:
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1579390#msg1579390
He estimates 1000 m/sec propagation speed for a seismic wave in that soil. The junkyard is about 4 km from the pad, so that would be a seismic wave travel time of about 4 seconds, vs 12 seconds in air.
Then the time delta would be 8 seconds for "ground vs air" wave speed.
Surely there must be dozens of security cameras recording sound scattered around the Cape?
They don't record sound
So: Other recordings needed to triangulate that "quieter bang sound a few seconds before the fireball goes off"?
Surely there must be dozens of security cameras recording sound scattered around the Cape?
Just wondering why Elon asks for "any recordings of the event" on Twitter.
From the TEL and with such cold temps I wonder if a LOX ball valve fractured with enough force in the flow to break through just outside the vehicle? If there was a filter it could go through it as well...
During development the launch vehicle has many strain gauges mounted, but what about the ground equipment?
No, I live a boring life... My point is that the piece break though near the LOX tank connection and deflects into the RP-1 tank section close by. Materials are very brittle at the temps SpaceX are working with and any material/manufaturing flaw could reveal itself in a spectacular fashion...From the TEL and with such cold temps I wonder if a LOX ball valve fractured with enough force in the flow to break through just outside the vehicle? If there was a filter it could go through it as well...
Pressure propagation down a pipe? Ever done the thing where you whack the top of a part full beer bottle and then laugh at the holder as it erupts into foam?
Just how big is that initial explosion?
The initial bang seems to be some form of fuel-air(oxygen) explosion. Has anyone given a reasonable estimate of just HOW MUCH fuel would be needed to form a bang of that size?
A few grams? A few kilograms? Hundreds?
Assuming the initial explosion is from somehow-vented/sprayed/aerosolysed RP1, we could go a long way to eliminating likely causes if we have a better idea of the actual volume of fuel needed to create that explosion.
I've tried to find info on this earlier in the thread, but my search-fu failed me.
Thanx,
Pete.
I think that sound before the explosion is a steel strut failing. Listen closely to the sounds in the video below and then listen again to the AMOS video (with headphones if possible). Both have that same distinctive ringing sound.
About this "sound through ground" discussion,
sorry guys, but why should be audible only the initial bang,
and not all the cacophony of the subsequent explosions?
Doesn't convince at all...
Thorsten
Anyone think that, if a root cause does not present itself, SpaceX will take another page out of the Silicon Valley playbook?
"Attempt to replicate the bug?"
A problem I'm told many programmers are famiiar with.Anyone think that, if a root cause does not present itself, SpaceX will take another page out of the Silicon Valley playbook?
"Attempt to replicate the bug?"
The problem is that there are a nearly infinite number of ways to make a rocket explode, and much of the hardware was completely destroyed. The T/E and much of the GSE will have to be rebuilt from scratch, and once you've done that if you fail to replicate the explosion, how do you know if the flaw was some hidden defect or failure in the now-destroyed GSE or some rare fault caused by a still-present design flaw?
A problem I'm told many programmers are famiiar with.Anyone think that, if a root cause does not present itself, SpaceX will take another page out of the Silicon Valley playbook?
"Attempt to replicate the bug?"
The problem is that there are a nearly infinite number of ways to make a rocket explode, and much of the hardware was completely destroyed. The T/E and much of the GSE will have to be rebuilt from scratch, and once you've done that if you fail to replicate the explosion, how do you know if the flaw was some hidden defect or failure in the now-destroyed GSE or some rare fault caused by a still-present design flaw?
Hydrazine is not feasible. It would have gone off in the fairing
Nice to see your personal and professional experience jibes with my engineering intuition.
So assuming an external fuel/air explosive event, any ideas how enough fuel could or would rise the 10' or so from the the apparently-unpressurized RP1 umbilicals? If RP1 loading was complete but the tank not yet at flight pressure, how does that happen? Could a check valve in the RP1 QD have failed, combined with a hole in the umbilical causing a vertical spray or mist up in the clouds of venting O2 gas?
I just don't get the mechanism yet.
just to touch on copv's one more time...
what state would the copv's be in now? would they have survived intact?
it would be nice to see pictures of them. just to put my mind at ease.
They all likely explodedDue to heat weakening them? If so they might look different than one that failed prior to the fire.
There are fire-resistant fluids. One is even water. The Dow family usually mixes glycol with water. Glycol, however as an aerosol, would still ignite.
Not sure about the others.
If someone could affirmatively state that the clamp piston is gas operated, then we could shut down my favorite hypothesis.
Do you know if there are non-flammable hydraulic fluids, and is it typical for rocket companies to use those non-flammable hydraulic fluids in their launch site hydraulics (ie stuff that is going to be operating near venting GOX)?
I think that sound before the explosion is a steel strut failing. Listen closely to the sounds in the video below and then listen again to the AMOS video (with headphones if possible). Both have that same distinctive ringing sound.
Compare how close those guys were standing vs how close the recording was taken from. Atmospheric attenuation hits high frequencies much harder than low frequencies. The spectrograph posted earlier shows that "pre-thunk" has pretty substantial energy up through the 4kHz band (btw, would it be possible for someone to get a snapshot spectrograph in dB/Hz for that brief sound?).
A frequency-based attenuation table is available here (https://en.wikibooks.org/wiki/Engineering_Acoustics/Outdoor_Sound_Propagation#Attenuation_by_atmospheric_absorption.5B5.5D_.5B6.5D_.5B7.5D).
If that sound had the vehicle as a direct source, you would see a much stronger bias to the low frequencies than you do over that kind of distance. In particular, a 4 km distance would result in an attenuation of around 100 dB in the 4 kHz band, which would basically render that effectively inaudible. There's simply no way that sound doesn't have a source much closer to the camera than the rocket.
increasingly trying to understand sound heard prior to explosion
Why are we talking about drones? We would have seen a drone on the video and SpaceX certainly would have seen it on on their pad cameras.
Because drones are the new favorite subject of the obsessively paranoid.
Personally I'm not being paranoid, there doesn't need to be any kind of conspiracy or deliberate action just someone stupid with a drone. Drones carry batteries, batteries can short or even explode. Plenty of people fly them far too close to airports, there have been many recorded near misses.
None of that has any practical basis in reality in this context.
Batteries burn (they "explode" in the sense of a pressure release and expansion, but there's no detonation) when you overcharge them, not in flight. I've seen hundreds of crashes, some into concrete, some into steel, and I've only once seen a battery burn and that was a very extreme case.
It's perfectly legal to fly near airports with notification, in most cases. The rule is "see and avoid" full-scale airplanes. Controlled and/or restricted airspace is another matter and my understand is that CCAFs is restricted.
Since Elon's tweet re the sound:
"Particularly trying to understand the quieter bang sound a few seconds before the fireball goes off. May come from rocket or something else."
I went back and did a much more detailed listen (and look using spectrogram) to the sound track of the video.
From the 60fps video I was able to determine a 12.14 sec sound travel time in air using the first visible sign of explosion (whatever the correct term is). I used this offset to time correct the spectrogram (attached) so that it is synchronised with the video.
Just out of interest I also tried a 4 sec time offset to see of any sounds match up with the video. IMHO they do, but nothing of great interest other then it appears the explosion would have been heard via the ground before hearing via the air.
Using some high and low pass filtering I was able to clearly hear many birds and to my surprise many frogs reasonably clearly from the video sound track.
IMO there are only two sounds that cannot identified. They occur 1 second apart.
I'm guessing these are the sounds Elon is referring to in his tweet?
They occur at 1:06.5 and 1:07.5 in the below time offset spectrogram.
Or at 1:18.64 and 1:19.64 in the original video.
Understanding the source of these sounds may help provide answers as the first sounds occurs 5.2 secs before the explosion.
Edit: Spelling, more image annotations.
Since Elon's tweet re the sound:
"Particularly trying to understand the quieter bang sound a few seconds before the fireball goes off. May come from rocket or something else."
I went back and did a much more detailed listen (and look using spectrogram) to the sound track of the video.
From the 60fps video I was able to determine a 12.14 sec sound travel time in air using the first visible sign of explosion (whatever the correct term is). I used this offset to time correct the spectrogram (attached) so that it is synchronised with the video.
Just out of interest I also tried a 4 sec time offset to see of any sounds match up with the video. IMHO they do, but nothing of great interest other then it appears the explosion would have been heard via the ground before hearing via the air.
Using some high and low pass filtering I was able to clearly hear many birds and to my surprise many frogs reasonably clearly from the video sound track.
IMO there are only two sounds that cannot identified. They occur 1 second apart.
I'm guessing these are the sounds Elon is referring to in his tweet?
They occur at 1:06.5 and 1:07.5 in the below time offset spectrogram.
Or at 1:18.64 and 1:19.64 in the original video.
Understanding the source of these sounds may help provide answers as the first sounds occurs 5.2 secs before the explosion.
Edit: Spelling, more image annotations.
Good work, almost there.
Now cut the spectrum image included to overlap the air transmitted vs ground transmitted waveforms.
The labeled "Animals reacting" is really the RUD in Progress of the stack collapse and impact of AMOS-6 + secondary Hydrazine detonation
. . . Any recordings from another distant camera in a different location that might have picked up the same sound would rule out that possibility and indicate it was a very loud sound from somewhere far off.
If that's the case, then maybe they could try triangulation.
. . . Any recordings from another distant camera in a different location that might have picked up the same sound would rule out that possibility and indicate it was a very loud sound from somewhere far off.
If that's the case, then maybe they could try triangulation.
Re: triangulation - if its possible to sync two or more audio tracks to within tens of ms, it should be possible to localize the source to within some 10s of feet, no? SpaceX ought to have been able to do that. Does that imply the sound came from an "expected" place - the area of the 2nd stage?
Maybe this was covered previously, if so, apologies.
What's the "standard" sampling rate for the sensors that are all over a rocket like this one? It appears from the public Elon tweets that none of the telemetry shows anything unusual until it's all going haywire.
OK, gang... using my geologic engineering background, i believe i have a plausible explanation of the *ploink* and rumble on the vid. YES is DOES COME FROM THE JUNKYARD!, but the explosion and subsequent fireball ARE to blame. Since the S1 is attached to the pad/ground, it transmits the pressure wave directly to the ground. This is why it registered on seismic equipment. since pressure waves travel much faster through the ground than in the compressible air, the transient noises in the video are caused by the explosion. The shock traveling through the ground will arrive to the microphone location before the sound traveling in the air. This shockwave/impulse caused something in the yard to tilt,rub,bang or rattle . Initial explosion shock arrival IS the *ploink* and fireball/collapse of the stack is the rattle. That should put everything to bed... what do you think Chris?
this will be for pressure or P-Wave impulses
since the coastal area of CCAFS is mostly unconsolidated sediment & sand, one can use 1000 meters/sec as velocity.
Here's the study from 2011 by University of Florida regarding seismic energy propagation in FLA
http://www.dot.state.fl.us/research-center/Completed_Proj/Summary_SMO/FDOT_BDK75_977-01_rpt.pdf
I'll let you have fun with the maths
So Space X is requesting if you have audio, photos or videos of their anomaly last week to please send to them but wouldn't it also help if they presented what evidence they have so far like their own video? Don't know if it some proprietary issue but just wondering.You do have a point, the NFS community did an incredible reconstructing the first water landing for them. Hand over what audio files may exist and see if the NFS community can reconstruct it...
This looks very convincing to me. Quite a number of features line up here, enough to convince me that the "thumps before" are just fast-arriving versions of the main event.Since Elon's tweet re the sound:
"Particularly trying to understand the quieter bang sound a few seconds before the fireball goes off. May come from rocket or something else."
I went back and did a much more detailed listen (and look using spectrogram) to the sound track of the video.
From the 60fps video I was able to determine a 12.14 sec sound travel time in air using the first visible sign of explosion (whatever the correct term is). I used this offset to time correct the spectrogram (attached) so that it is synchronised with the video.
Just out of interest I also tried a 4 sec time offset to see of any sounds match up with the video. IMHO they do, but nothing of great interest other then it appears the explosion would have been heard via the ground before hearing via the air.
Using some high and low pass filtering I was able to clearly hear many birds and to my surprise many frogs reasonably clearly from the video sound track.
IMO there are only two sounds that cannot identified. They occur 1 second apart.
I'm guessing these are the sounds Elon is referring to in his tweet?
They occur at 1:06.5 and 1:07.5 in the below time offset spectrogram.
Or at 1:18.64 and 1:19.64 in the original video.
Understanding the source of these sounds may help provide answers as the first sounds occurs 5.2 secs before the explosion.
Edit: Spelling, more image annotations.
Good work, almost there.
Now cut the spectrum image included to overlap the air transmitted vs ground transmitted waveforms.
The labeled "Animals reacting" is really the RUD in Progress of the stack collapse and impact of AMOS-6 + secondary Hydrazine detonation
OK, gang... using my geologic engineering background, i believe i have a plausible explanation of the *ploink* and rumble on the vid. YES is DOES COME FROM THE JUNKYARD!, but the explosion and subsequent fireball ARE to blame. Since the S1 is attached to the pad/ground, it transmits the pressure wave directly to the ground. This is why it registered on seismic equipment. since pressure waves travel much faster through the ground than in the compressible air, the transient noises in the video are caused by the explosion. The shock traveling through the ground will arrive to the microphone location before the sound traveling in the air. This shockwave/impulse caused something in the yard to tilt,rub,bang or rattle . Initial explosion shock arrival IS the *ploink* and fireball/collapse of the stack is the rattle. That should put everything to bed... what do you think Chris?
this will be for pressure or P-Wave impulses
since the coastal area of CCAFS is mostly unconsolidated sediment & sand, one can use 1000 meters/sec as velocity.
Here's the study from 2011 by University of Florida regarding seismic energy propagation in FLA
http://www.dot.state.fl.us/research-center/Completed_Proj/Summary_SMO/FDOT_BDK75_977-01_rpt.pdf
I'll let you have fun with the maths
Working from another angle, the distance from the epicentre to the USLR camera is 4.34 kms.
If the speed of sound is 343.2 m/s, the sound should take 4340 / 343.2 = 12.64 seconds to arrive.
If I look at the audio in a waveform editor, I can mark the visible explosion at 13.467 - 12.64 = 0.836 seconds.
The first two events, the squeak and the clunk are at the 6.7 and 8.3 second marks, that is 5.864 and 7.464 after the explosion.
For the squeak to be ground transmitted, the velocity would be 4340 / 5.864 = 740.1 m/s.
For the clunk to be ground transmitted, the velocity would be 4340 / 7.464 = 581.46 m/s.
If 1000 m/s is the velocity of the pressure wave in the soil, then the sounds are not arriving quickly enough to be related to the explosion. Does anyone have a reason to suggest that the speed of transmission might be significantly less than 1000 m/s?
Here's one I don't think is in the list:
a leak, even a tiny one, in the S2 TEB system. It auto ignites in O2 at -20°C. Is it tanked on the ground or late loaded through the strongback?
Here's one I don't think is in the list:
a leak, even a tiny one, in the S2 TEB system. It auto ignites in O2 at -20°C. Is it tanked on the ground or late loaded through the strongback?
It is beginning to look (to me) like Spacex may wind up doing a complete 'clean sheet' redesign of the second stage. I think this is the 'hardest' problem they have ever run into, and they may not ever find a 'smoking gun' cause (I think it is already too late for that.) Would reverting to 'non-chilled RP1 and LOX do anything to solve the problem (I'm thinking Mr. Musk would pull his eyeteeth out before regressing to an earlier system/procedure)?Re: clean sheet redesign of 2nd stage. Why? :
It is beginning to look (to me) like Spacex may wind up doing a complete 'clean sheet' redesign of the second stage. I think this is the 'hardest' problem they have ever run into, and they may not ever find a 'smoking gun' cause (I think it is already too late for that.) Would reverting to 'non-chilled RP1 and LOX do anything to solve the problem (I'm thinking Mr. Musk would pull his eyeteeth out before regressing to an earlier system/procedure)?Re: clean sheet redesign of 2nd stage. Why? :
1. They don't know the root cause was in the second stage.
2. The first stage and second stage are as similar as two stages can be. If the second stage did contain the root cause, why would the first stage be exempt from the same (undetermined) short coming?
3. If they don't know the root cause, they don't know how to avoid designing in the exact same mode of failure.
Re: densified propellent:
They don't know the root cause yet, what's the point of randomly changing things?
I don't know what they will do if they don't discover a root cause. But they won't redesign the second stage just hoping that fixes the problem. I guess at some point they'd double down on QA, GSE robustness safety, propellent purity, sensors, cameras and microphones. The first steps hoping it doesn't happen again, the latter hoping if it does they'll get a definitive answer. But that bleak possibility is months away. There is still debris to collect, a TEL to disassemble and inspect, GSE to inspect and heads to scratch.
The second stage doesn't use densified propellant (?)
Thorsten
Since Elon's tweet re the sound:
"Particularly trying to understand the quieter bang sound a few seconds before the fireball goes off. May come from rocket or something else."
I went back and did a much more detailed listen (and look using spectrogram) to the sound track of the video.
From the 60fps video I was able to determine a 12.14 sec sound travel time in air using the first visible sign of explosion (whatever the correct term is). I used this offset to time correct the spectrogram (attached) so that it is synchronised with the video.
Just out of interest I also tried a 4 sec time offset to see of any sounds match up with the video. IMHO they do, but nothing of great interest other then it appears the explosion would have been heard via the ground before hearing via the air.
Using some high and low pass filtering I was able to clearly hear many birds and to my surprise many frogs reasonably clearly from the video sound track.
IMO there are only two sounds that cannot identified. They occur 1 second apart.
I'm guessing these are the sounds Elon is referring to in his tweet?
They occur at 1:06.5 and 1:07.5 in the below time offset spectrogram.
Or at 1:18.64 and 1:19.64 in the original video.
Understanding the source of these sounds may help provide answers as the first sounds occurs 5.2 secs before the explosion.
Edit: Spelling, more image annotations.
Good work, almost there.
Now cut the spectrum image included to overlap the air transmitted vs ground transmitted waveforms.
The labeled "Animals reacting" is really the RUD in Progress of the stack collapse and impact of AMOS-6 + secondary Hydrazine detonation
Shifting the spectrogram further back in time ALMOST but not exactly lines up... What does this do to the speed calculations? It also shows an earlier blip. I need to listen to the audio to see if it's really related.
OK, gang... using my geologic engineering background, i believe i have a plausible explanation of the *ploink* and rumble on the vid. YES is DOES COME FROM THE JUNKYARD!, but the explosion and subsequent fireball ARE to blame. Since the S1 is attached to the pad/ground, it transmits the pressure wave directly to the ground. This is why it registered on seismic equipment. since pressure waves travel much faster through the ground than in the compressible air, the transient noises in the video are caused by the explosion. The shock traveling through the ground will arrive to the microphone location before the sound traveling in the air. This shockwave/impulse caused something in the yard to tilt,rub,bang or rattle . Initial explosion shock arrival IS the *ploink* and fireball/collapse of the stack is the rattle. That should put everything to bed... what do you think Chris?
this will be for pressure or P-Wave impulses
since the coastal area of CCAFS is mostly unconsolidated sediment & sand, one can use 1000 meters/sec as velocity.
Here's the study from 2011 by University of Florida regarding seismic energy propagation in FLA
http://www.dot.state.fl.us/research-center/Completed_Proj/Summary_SMO/FDOT_BDK75_977-01_rpt.pdf
I'll let you have fun with the maths
Working from another angle, the distance from the epicentre to the USLR camera is 4.34 kms.
If the speed of sound is 343.2 m/s, the sound should take 4340 / 343.2 = 12.64 seconds to arrive.
If I look at the audio in a waveform editor, I can mark the visible explosion at 13.467 - 12.64 = 0.836 seconds.
The first two events, the squeak and the clunk are at the 6.7 and 8.3 second marks, that is 5.864 and 7.464 after the explosion.
For the squeak to be ground transmitted, the velocity would be 4340 / 5.864 = 740.1 m/s.
For the clunk to be ground transmitted, the velocity would be 4340 / 7.464 = 581.46 m/s.
If 1000 m/s is the velocity of the pressure wave in the soil, then the sounds are not arriving quickly enough to be related to the explosion. Does anyone have a reason to suggest that the speed of transmission might be significantly less than 1000 m/s?
I can appreciate that a surface wave would arrive before a wave traveling through the air, but would it actually make an audible sound? I can see how it might shake the camera, but would the microphone pick it up?A microphone might not, but the junkyard the microphone is sitting in may react in ways a microphone can detect.
Are any of the external "rocket cameras" located in the area of interest? If a battery caught fire or exploded in that oxygen rich environment...
You misunderstood me, I'm talking about the one's mounted "on the rocket" to give us pretty videos from it as it launches...Are any of the external "rocket cameras" located in the area of interest? If a battery caught fire or exploded in that oxygen rich environment...
With electrical telemetry you don't need any cameras for that part of the fault tree...
Are any of the external "rocket cameras" located in the area of interest? If a battery caught fire or exploded in that oxygen rich environment...
I have no idea Jim, my only thought was about a battery failure or short. Your thoughts?Are any of the external "rocket cameras" located in the area of interest? If a battery caught fire or exploded in that oxygen rich environment...
How long do you think it transmitted the video
I had an interesting thought on how you might get LOX on the outside/bottom edge of the LOX tank, near the RP-1 tank vent without a leak.Welcome to the forum! :) It's a long thread to read but I think I recall some making comments about static discharges as well. Have fun!
At the sub chilled LOX temperatures that are present inside the tank, it is highly likely that you would actually get liquid oxygen condensing out of the surrounding air onto the rocket body.
This could also explain why this failure mode didn't crop up before... The sub-chilled LOX is a relatively new procedure and almost no one else has used it (might explain why they had a almost unheard of fueling failure). Combine that with changes in humidity and wind conditions and that could put a RP-1 plume and nearby liquid oxygen in the right place for a spark during LOX filling to ignite it.
Based on the approx. location of the start of the flame, the common bulkhead support cradle on the TE could possibly provide a location for a static discharge to occur near a suspected RP-1 tank vent and condensing O2.
It seems like a bit of a stretch but I remember making LOX on the outside of a pop can filled with LN2.
-340F is cold enough to liquify both Nitrogen and Oxygen in the atmosphere. I thought that was one of the big headaches of LH2 was that you had to deal with Liquid oxygen forming on the tanks and such. ~Jon
Liquid hydrogen and liquid helium are both so cold that they can liquefy the air they contact. For example, liquid air can condense on a surface cooled by liquid hydrogen or helium. Nitrogen evaporates more rapidly than oxygen from the liquid air. This action leaves behind a liquid air mixture which, when evaporated, gives a high concentration of oxygen. This oxygen-enriched air now presents all of the same hazards as oxygen.
Shifting the spectrogram further back in time ALMOST but not exactly lines up... What does this do to the speed calculations? It also shows an earlier blip. I need to listen to the audio to see if it's really related.
Not sure if you have the tools to do this, I'm not sure exactly how to do this either.
IF the clang and thunk are P & S waves, there is a chance that the camera is shaking at the same times, and not prior or after until the big 'un.
I tried focusing on two lights at the bottom during the clang and the thunk, thinking they wouldn't move unless the camera did, and boy was I wrong. They're wobbling like mad because of other explosions at the same time that the clang and thump happen. I'll try the tower next, but if you can synch the audio and video maybe you could look at shake and save me a mouse induced carpel tunnel event? :)
Welcome to the forum! :) It's a long thread to read but I think I recall some making comments about static discharges as well. Have fun!
There are posts on this earlier in the thread
I have had lots of experience burning TEB in an oxygen environment. Let's remember it is a fuel not an explosive. The only flame you would get is until it is consumed. The flame front will not propagate through the oxygen cloud unless some other fuel is present.Here's one I don't think is in the list:
a leak, even a tiny one, in the S2 TEB system. It auto ignites in O2 at -20°C. Is it tanked on the ground or late loaded through the strongback?
I don't know but I would say on the ground in the hangar, because
a. we don't see a container on the TEL for it.
b. running a line from the ground all the way up the TEL to the second stage means a lot of fluid that would have to be purge out of the line after filling. Maybe more than would be needed by the stage
Something I don't recall being mentioned yet are stress fractures. This could be caused by a number of of things including handling issues. The thing about stress fractures is that they can act as a time bomb failing some time after the event that causes them. For high pressure pipelines they could take months or years before failing.Yes, mentioned something similar at the common bulkhead, many pages back...
One argument for a stress fracture is that the explosion occurred during LOX loading, with super cooled LOX providing the additional stress to cause the failure. The actual failure could be quite small resulting in a plume of O2 being sprayed out prior to the ignition event.
I suppose this logic could also apply to chilled RP-1, providing the fuel required. (LOX really isn't required here).
The only thing in favor of this is the timing with the metal walls of S-2 being stressed by the loading operations under way.
Shifting the spectrogram further back in time ALMOST but not exactly lines up... What does this do to the speed calculations? It also shows an earlier blip. I need to listen to the audio to see if it's really related.
Not sure if you have the tools to do this, I'm not sure exactly how to do this either.
IF the clang and thunk are P & S waves, there is a chance that the camera is shaking at the same times, and not prior or after until the big 'un.
I tried focusing on two lights at the bottom during the clang and the thunk, thinking they wouldn't move unless the camera did, and boy was I wrong. They're wobbling like mad because of other explosions at the same time that the clang and thump happen. I'll try the tower next, but if you can synch the audio and video maybe you could look at shake and save me a mouse induced carpel tunnel event? :)
Here's the synced video. I can't see anything happening... Now I'm not sure which thread this should go in...
Are any of the external "rocket cameras" located in the area of interest? If a battery caught fire or exploded in that oxygen rich environment...Next up: all pad technicians get body cameras.
Welcome to the forum! :) It's a long thread to read but I think I recall some making comments about static discharges as well. Have fun!
I have seen quite some talk on how LOX generates a decent amount of static during flow. But the only way they had LOX getting outside the rocket at that location was with a break at the common bulkhead.
I wanted to add a possible mechanism by which LOX ends up outside the rocket near the common bulkhead support on the strongback (which is pretty much the apparent epicenter of the first sign of fire). There has also been talk of the RP-1 tank vent being near there. Add that to the fact that earlier launches, except for the last few, would have had warmer LOX (thus no LOX condensation) and you have a possible change that could have led to such a rare event, in rocket history, occurring.
At that rate, if the LOX on the outside of the tank came in contact with any organic matter (it wouldn't have to be RP-1). What do they use to prevent denting the common bulkhead with the TE support? Any sort of foam?
SpaceX apparently housed some or all of their telemetry servers at or very close to the pad, and they were destroyed by the fire.
Re: triangulation - if its possible to sync two or more audio tracks to within tens of ms, it should be possible to localize the source to within some 10s of feet, no? SpaceX ought to have been able to do that. Does that imply the sound came from an "expected" place - the area of the 2nd stage?
What audio tracks?
SpaceX apparently housed some or all of their telemetry servers at or very close to the pad, and they were destroyed by the fire.
Far be it from me to question your sources, but that doesn't jive even remotely with earlier statements. Telemetry being lost precludes telemetry being reviewed. If the supposed lost servers weren't hardened AND located close enough to burn in the aftermath, how would they not have been destroyed or at least damaged during a previous nominal launch?
Re: triangulation - if its possible to sync two or more audio tracks to within tens of ms, it should be possible to localize the source to within some 10s of feet, no? SpaceX ought to have been able to do that. Does that imply the sound came from an "expected" place - the area of the 2nd stage?
What audio tracks?
Huh. It hadn't occurred to me that SpaceX might not have multiple video/audio recordings of the static fire. That would be unfortunate.
I was surprised by this info too, that's why I said make of it what you will. I also don't know what public statements SpaceX has actually made that would contradict it. To what "earlier statements" do you refer?
As for the second half of the comment, it's quite possibly electronics are hardened against a 3 second static fire (or even a 2 minute static fire) but still unable to tolerate an extended-duration 1,000 degree-plus RP1 and/or hypergolic fire, impact with high-speed debris from a venting COPV, etc. SpaceX notably doesn't use old-fashioned blockhouses these days, you'll note. Most launch providers don't.
Anyway, I'm not wedded to this info - the person I got it from is far better placed than me to know what's going on in and around CCAFS right now, but you know, there could be subtle misunderstandings on their part or in how it was explained to me.
***ARC FLASH**
I'm not sure if it has been noted here yet in the discussion - surprised if it hasn't been - when an electrical arc flash occurs it makes a "noise" - snap, crackle, pop, boom - as it were...
As always, for what it is worth!
It's basically swampland. You're not going to get a surface wave, period.When I witnessed launches at KSC and the Cape, sometimes from less than 3 miles distant, I could feel the ground move beneath my feet before the sound of the launch arrived. Isn't that a "surface wave"?
***ARC FLASH**
I'm not sure if it has been noted here yet in the discussion - surprised if it hasn't been - when an electrical arc flash occurs it makes a "noise" - snap, crackle, pop, boom - as it were...
As always, for what it is worth!
What voltages do you think are used on Launch vehicles?
***ARC FLASH**
I'm not sure if it has been noted here yet in the discussion - surprised if it hasn't been - when an electrical arc flash occurs it makes a "noise" - snap, crackle, pop, boom - as it were...
As always, for what it is worth!
What voltages do you think are used on Launch vehicles?
An ungrounded system can develop millions of volts of surface potential just from being in the wind.
I'm not saying this system is ungrounded, but if a ground failed or separated, a large potential could develop very quickly.
Audio is not used
Re: triangulation - if its possible to sync two or more audio tracks to within tens of ms, it should be possible to localize the source to within some 10s of feet, no? SpaceX ought to have been able to do that. Does that imply the sound came from an "expected" place - the area of the 2nd stage?
What audio tracks?
Huh. It hadn't occurred to me that SpaceX might not have multiple video/audio recordings of the static fire. That would be unfortunate.
Audio is not used
From my understanding of Hydrazine's (actually MMH I believe) properties, it would certainly have carried the initial explosion immediately into the payload fairing, which was clearly uninvolved in the early sequence of events
I was thinking about this a lot last night, trying to hypothesize a system that would comport with this possible news. Imagine a very high bandwidth telemetry system - it will require a lot of signal bandwidth back to the storage system and then a relatively smaller bandwidth to the consoles of the folks working a mission. Remember, controllers only look at some of the data in realtime but can often focus in more closely on systems as necessary, pulling up some data and looking away from others on the fly as needed.
I was surprised by this info too, that's why I said make of it what you will. I also don't know what public statements SpaceX has actually made that would contradict it. To what "earlier statements" do you refer?
As for the second half of the comment, it's quite possibly electronics are hardened against a 3 second static fire (or even a 2 minute static fire) but still unable to tolerate an extended-duration 1,000 degree-plus RP1 and/or hypergolic fire, impact with high-speed debris from a venting COPV, etc. SpaceX notably doesn't use old-fashioned blockhouses these days, you'll note. Most launch providers don't.
Anyway, I'm not wedded to this info - the person I got it from is far better placed than me to know what's going on in and around CCAFS right now, but you know, there could be subtle misunderstandings on their part or in how it was explained to me.
Not using blockhouses indicates to me that all the data is transmitted well away from the pad to servers, certainly not that they are using servers close enough to have been destroyed.
Also, one of Elon's tweets mentioned vehicle sensor data, indicating they have telemetry data.
Bandwidth is cheap. CWDM Ethernet LX-4 provides 10Gbit/s per fibre. DWDM can achieve 1.6 Tbit/s per fibre with cheap of the shelf hardware. A cable contains multiple fibres (12).I was thinking about this a lot last night, trying to hypothesize a system that would comport with this possible news. Imagine a very high bandwidth telemetry system - it will require a lot of signal bandwidth back to the storage system and then a relatively smaller bandwidth to the consoles of the folks working a mission. Remember, controllers only look at some of the data in realtime but can often focus in more closely on systems as necessary, pulling up some data and looking away from others on the fly as needed.
I was surprised by this info too, that's why I said make of it what you will. I also don't know what public statements SpaceX has actually made that would contradict it. To what "earlier statements" do you refer?
As for the second half of the comment, it's quite possibly electronics are hardened against a 3 second static fire (or even a 2 minute static fire) but still unable to tolerate an extended-duration 1,000 degree-plus RP1 and/or hypergolic fire, impact with high-speed debris from a venting COPV, etc. SpaceX notably doesn't use old-fashioned blockhouses these days, you'll note. Most launch providers don't.
Anyway, I'm not wedded to this info - the person I got it from is far better placed than me to know what's going on in and around CCAFS right now, but you know, there could be subtle misunderstandings on their part or in how it was explained to me.
Not using blockhouses indicates to me that all the data is transmitted well away from the pad to servers, certainly not that they are using servers close enough to have been destroyed.
Also, one of Elon's tweets mentioned vehicle sensor data, indicating they have telemetry data.
Now imagine a data system created by Silicon Valley types who think they have a more efficient way than running miles of high-data rate cabling back to launch control. Instead, limit the very high bandwidth runs from the vehicle down to a semi-hardened bunker near the pad then run a relatively "thin" set of data cables back to launch control to allow controllers to see what they want in realtime but store everything else for later download and analysis. "What could go wrong, right? Civilian rockets haven't blown up on the pad in 50+ years!" Remember, this system - whatever the details - was conceived before the Antares mishap when LC-40 was first converted.
Anyway, as I said I have no personal knowledge but thought it worth bringing up for discussion. I can imagine a data system architecture that lines up with the info - and even justification for such an architecture at the time it might have been created - but don't know if it's true. In fact we may never know unless a government investigation report is released that delineates difficulties experienced pursuing the investigation.
Curious question on the servers wiped clean with burning RP-1 and LOX. Is it a flesh wound, or is it possible to send the remains out to one of those data recovery places? I know heat can do a number on drives. Curious if there is hope for the lost servers.Got no clue, man. I passed along what I heard purely for the sake of discussion.
Got no clue, man. I passed along what I heard purely for the sake of discussion.
Long time listener, first time caller. I have read all 2100+ messages so far in this board and I haven't heard this exact theory I'm about to put forth.
I call this the "slow slump" theory. Since the static fire is the first time the full stack was fully integrated and was being fueled, I propose that there was not necessarily a manufacturing flaw but a borderline tolerance flaw, along with a borderline tolerance mating of the strongback to the stack. As the RP1 was being loaded the rocket would be creaking and would be triggering sensors within the rocket, but the difference would be there would be an accumulation of borderline tolerance flaws that would cause the rocket to slowly "slump" along the side of the rocket facing the strongback and would have lead to a minor leak of the rocket near the top of RP1 stage 2 tank only when the tank was full (around the time of the anomaly occurred). This leak was minor enough it would not have been observed easily on camera, but the RP1 was being atomized by LOX venting from S1 and carried up to be ignited by the oxygen rich venting on S2 until there was enough fuel to be ignited.
Sensor readings long before the anomaly would look different than prior static firings of the F9. The cause of the anomaly was a long running event while everyone is looking for a fast cascade of sensor reading, but culminated in the footage we have all seen in the video. The weak part of this theory is the ignition of this FAE event, but I'm postulating that given enough RP1, and oxidizer in this environment that any rust point on the strongback could have triggered the FAE, and subsequent LOV.
I'm just a curious armchair rocket sturgeon looking for answers like everyone else.
Well, that is a new idea. :) Been a while.... :)
Does your theory require S1 LOX to go up? Couldn't the RP1 just come down and start evaporating?
Kerosine's vapor pressure is 0.5kPa at 20 degrees C. Water, and beer, by comparison is 2.4. It would, me thinks, take a long time to accumulate enough vapor, and the wind was blowing to the left...
We now understand air oxygen will condense on the supercooled oxygen tank.
Obviously not the pad cams but just confirming something I thought I remembered reading, wasn't it brought up in the last investigation that the accelerometers on the craft itself were sensitive enough to be able to reproduce sound?
Somebody PLEASE tell me there wasn't any Kapton insulated wiring on the TE or other GSE.
Kapton + salt atmosphere is bad news as the insulation cracks, causes shorts and catches fire. In an oxygen rich atmosphere near LOx vents likely to be worse.
Earlier in this thread there were many posts regarding the large diameter duct with an ‘S’ bend in the upper section of the TEL.
It was established that this upper duct solely carried a/c for the payload/fairing which at a later stage in the launch sequence was transitioned to carrying gaseous purge nitrogen.
The payload’s hydrazine fuel is pre-loaded before the satellite is encased by the fairing.
Jim has pointed out that the fairing vents to the exterior and that there is no return path for nitrogen or a/c air.
However, the fairing must be pressurized somewhat above atmospheric pressure for the nitrogen purge system to work.
What is the possibility that some payload anomaly occurred where hydrazine fuel was accidentally discharged and somehow ended up coming out from the fairing then subsequently running down the side of S2 until it came into contact with the venting O2 at the point where an ignition occurred then leading to the LOV?
There are two types of cameras. Gopro, which stores the data and the telemetry cameras, which we can see liveThanks Jim, So we have the Gopros in the faring with their own batteries and the telemetry cameras off Falcon's mains which are located where on the second stage if publicly known?
There are two types of cameras. Gopro, which stores the data and the telemetry cameras, which we can see liveThanks Jim, So we have the Gopros in the faring with their own batteries and the telemetry cameras off Falcon's mains which are located where on the second stage if publicly known?
The only 'go pro' cameras I know of in the second stage are on either side of the M1-vac and one on top of the second stage to view fairing sep and payload deploy. None near the apparent center of the explosion.
For the historians like Ed, was this failure the largest hydrazine pad handling accident at the cape?
From my understanding of Hydrazine's (actually MMH I believe) properties, it would certainly have carried the initial explosion immediately into the payload fairing, which was clearly uninvolved in the early sequence of eventsWouldn't the vents be somewhat one way? That and gravity might be enough to prevent it going internal to the fairing. Plus there would be no oxidizer in the fairing if only the "fuel" part was leaking.
1. Wouldn't the vents be somewhat one way? That and gravity might be enough to prevent it going internal to the fairing.
2. Plus there would be no oxidizer in the fairing if only the "fuel" part was leaking.
3. So two questions: Would the payload have been monitored AT ALL during the static fire?
4 Is Hydrazine hypergolic in oxygen enriched air?
Quoteincreasingly trying to understand sound heard prior to explosion
This is very telling. Points to one of two things:
Internal failure in the lox tank or GSE failure that rapidly overpressurized the tank or its internals.
FTS is ruled out (thanks for the info on this jim).
External fae is ruled out due to a variety of reasons though the wind is a big one.
Gse is not something I can completely rule out but it seems very unlikely, the system itself would probably fail first not the lox tank.
Payload as source is ruled out due to the payload not blowing up until after it fell off what was left of the TE and other aforementioned reasons regarding payload fuel.
Really IMHO only thing that fits in something within the lox tank. So COPV or other internal ignition+overpressure ignition not yet found.
My guess is the reason why it is so hard to pinpoint is because it happened extremely fast.
Still there are more questions now I think than we had before and not really any answers.
Here is the point though. The failure was in the LOX tank or very near to it in the second stage. I think this is almost 100% certain given spacex's own statements and the failure nature itself.
Second, to me this leads back to the original problem which brought down crs7: quality control.
Spacex is apparently learning the hard way they cannot keep doing things internally like a startup company. They need to seriously rethink their quality control program and how they test tankage components. They have been criticized by both other other industry figures and others for this in the recent past and have ignored the criticism as far more knowledgeable members on this site are no doubt aware.
Basically the short version, and I will preface this by saying that it's as I see it, is they need to get with the program already. Innovation is great but constantly changing component design and manufacture in the quest for efficiency is a recipe for these kinds of failures every time.
I suspect they will make real changes this time because the alternative will be losing contracts if this happens again.
Bandwidth is cheap. CWDM Ethernet LX-4 provides 10Gbit/s per fibre. DWDM can achieve 1.6 Tbit/s per fibre with cheap of the shelf hardware. A cable contains multiple fibres (12).sure, but are they going to have optical links to the rocket? If the link to the rocket is electrical they'll need some device near the pad to convert from electrical to optical.. and that may introduce some amount (microseconds to milliseconds) of buffering and packetization delay which would increase the amount of data lost over a system which merely repeated the signal a bit at a time...
Bandwidth is cheap. CWDM Ethernet LX-4 provides 10Gbit/s per fibre. DWDM can achieve 1.6 Tbit/s per fibre with cheap of the shelf hardware. A cable contains multiple fibres (12).sure, but are they going to have optical links to the rocket? If the link to the rocket is electrical they'll need some device near the pad to convert from electrical to optical.. and that may introduce some amount (microseconds to milliseconds) of buffering and packetization delay which would increase the amount of data lost over a system which merely repeated the signal a bit at a time...
Would not be surprised to see multiple 1000base-T twisted-pair gigabit ethernet links off the rocket (spec says max cable length ~100m) running to one or more ethernet switches on the pad (or even up on the TEL!) with an optical uplink off the pad.
This might be an explanation for the supposedly lost telemetry. Maybe a few milliseconds worth of data was still in the (data) pipeline, when said pipeline got doused with LOX or burned to a crisp.Bandwidth is cheap. CWDM Ethernet LX-4 provides 10Gbit/s per fibre. DWDM can achieve 1.6 Tbit/s per fibre with cheap of the shelf hardware. A cable contains multiple fibres (12).sure, but are they going to have optical links to the rocket? If the link to the rocket is electrical they'll need some device near the pad to convert from electrical to optical.. and that may introduce some amount (microseconds to milliseconds) of buffering and packetization delay which would increase the amount of data lost over a system which merely repeated the signal a bit at a time...
Would not be surprised to see multiple 1000base-T twisted-pair gigabit ethernet links off the rocket (spec says max cable length ~100m) running to one or more ethernet switches on the pad (or even up on the TEL!) with an optical uplink off the pad.
Fiber is used to go off the pad.
This brings up an issue again. ethernet is the wrong medium for telemetry within and coming off the rocket. packetization means data can be lost in incidents such as this. And timing can get screw up. Serial data rules for these instances.
Quoteincreasingly trying to understand sound heard prior to explosion
This is very telling. Points to one of two things:
Internal failure in the lox tank or GSE failure that rapidly overpressurized the tank or its internals.
FTS is ruled out (thanks for the info on this jim).
External fae is ruled out due to a variety of reasons though the wind is a big one.
Gse is not something I can completely rule out but it seems very unlikely, the system itself would probably fail first not the lox tank.
Payload as source is ruled out due to the payload not blowing up until after it fell off what was left of the TE and other aforementioned reasons regarding payload fuel.
Really IMHO only thing that fits in something within the lox tank. So COPV or other internal ignition+overpressure ignition not yet found.
My guess is the reason why it is so hard to pinpoint is because it happened extremely fast.
Still there are more questions now I think than we had before and not really any answers.
Here is the point though. The failure was in the LOX tank or very near to it in the second stage. I think this is almost 100% certain given spacex's own statements and the failure nature itself.
Second, to me this leads back to the original problem which brought down crs7: quality control.
Spacex is apparently learning the hard way they cannot keep doing things internally like a startup company. They need to seriously rethink their quality control program and how they test tankage components. They have been criticized by both other other industry figures and others for this in the recent past and have ignored the criticism as far more knowledgeable members on this site are no doubt aware.
Basically the short version, and I will preface this by saying that it's as I see it, is they need to get with the program already. Innovation is great but constantly changing component design and manufacture in the quest for efficiency is a recipe for these kinds of failures every time.
I suspect they will make real changes this time because the alternative will be losing contracts if this happens again.
Long time listener, first time caller. I have read all 2100+ messages so far in this board and I haven't heard this exact theory I'm about to put forth.
I call this the "slow slump" theory. Since the static fire is the first time the full stack was fully integrated and was being fueled, I propose that there was not necessarily a manufacturing flaw but a borderline tolerance flaw, along with a borderline tolerance mating of the strongback to the stack. As the RP1 was being loaded the rocket would be creaking and would be triggering sensors within the rocket, but the difference would be there would be an accumulation of borderline tolerance flaws that would cause the rocket to slowly "slump" along the side of the rocket facing the strongback and would have lead to a minor leak of the rocket near the top of RP1 stage 2 tank only when the tank was full (around the time of the anomaly occurred). This leak was minor enough it would not have been observed easily on camera, but the RP1 was being atomized by LOX venting from S1 and carried up to be ignited by the oxygen rich venting on S2 until there was enough fuel to be ignited.
Sensor readings long before the anomaly would look different than prior static firings of the F9. The cause of the anomaly was a long running event while everyone is looking for a fast cascade of sensor reading, but culminated in the footage we have all seen in the video. The weak part of this theory is the ignition of this FAE event, but I'm postulating that given enough RP1, and oxidizer in this environment that any rust point on the strongback could have triggered the FAE, and subsequent LOV.
I'm just a curious armchair rocket sturgeon looking for answers like everyone else.
Welcome to the forum! :)Long time listener, first time caller. I have read all 2100+ messages so far in this board and I haven't heard this exact theory I'm about to put forth.
I call this the "slow slump" theory. Since the static fire is the first time the full stack was fully integrated and was being fueled, I propose that there was not necessarily a manufacturing flaw but a borderline tolerance flaw, along with a borderline tolerance mating of the strongback to the stack. As the RP1 was being loaded the rocket would be creaking and would be triggering sensors within the rocket, but the difference would be there would be an accumulation of borderline tolerance flaws that would cause the rocket to slowly "slump" along the side of the rocket facing the strongback and would have lead to a minor leak of the rocket near the top of RP1 stage 2 tank only when the tank was full (around the time of the anomaly occurred). This leak was minor enough it would not have been observed easily on camera, but the RP1 was being atomized by LOX venting from S1 and carried up to be ignited by the oxygen rich venting on S2 until there was enough fuel to be ignited.
Sensor readings long before the anomaly would look different than prior static firings of the F9. The cause of the anomaly was a long running event while everyone is looking for a fast cascade of sensor reading, but culminated in the footage we have all seen in the video. The weak part of this theory is the ignition of this FAE event, but I'm postulating that given enough RP1, and oxidizer in this environment that any rust point on the strongback could have triggered the FAE, and subsequent LOV.
I'm just a curious armchair rocket sturgeon looking for answers like everyone else.
I'm thinking this is the way to look. It looks like a fuel air explosion. For that volume to develop, it seems like it would take some time. And the way the wind is blowing, seems likely at least one part, fuel or O2 would come from the GSE and blow towards the vehicle. Perhaps fuel was sprayed out and began mixing with O2 by the rocket. Then a spark near the rocket/GSE interface occurred causing the accident.
Need to look in detail at the video a ways before the accident to see if anything different can be seen, especially around the GSE.
This brings up an issue again. ethernet is the wrong medium for telemetry within and coming off the rocket. packetization means data can be lost in incidents such as this. And timing can get screw up. Serial data rules for these instances.
This brings up an issue again. ethernet is the wrong medium for telemetry within and coming off the rocket. packetization means data can be lost in incidents such as this. And timing can get screw up. Serial data rules for these instances.
Loss is not a given on switched ethernet. Also the minimum frame time at 10Gbps is only 67 nanoseconds. At level, the amount of time it takes your operating system to finish an interrupt will be the driving factor in timing.
Spacex is apparently learning the hard way they cannot keep doing things internally like a startup company. They need to seriously rethink their quality control program and how they test tankage components. They have been criticized by both other other industry figures and others for this in the recent past and have ignored the criticism as far more knowledgeable members on this site are no doubt aware.Just a small point but AFAIK the struts were not "doing things internally." They were bought from a 3rd party, who I presume won't be supplying SX with anything else anytime soon. :(
Basically the short version, and I will preface this by saying that it's as I see it, is they need to get with the program already. Innovation is great but constantly changing component design and manufacture in the quest for efficiency is a recipe for these kinds of failures every time.In fact it's an argument for bringing more in house as much as revamping their QC on externally made components. both of which I suspect they will consider doing, depending on the root cause analysis.
I suspect they will make real changes this time because the alternative will be losing contracts if this happens again.Just to be clear IIRC SX said some of the struts they tested were 1/10 the design strength.
still packeting is good for losing data
still packeting is good for losing dataPacketization happens randomly between generation and storage, because everything has a buffer, that's the nature of being digital. Even serial UART's have buffers. It's just formally controlled in the link layer when using ethernet protocol. As long as the system is designed to control the maximum amount of data outstanding, it's fine. The only way to avoid the whole thing would be to go back to hard analog lines from every single sensor to recording medium, and no one wants to do that, or needs to if properly designed. Like I said, with 10Gbps ethernet you can send exactly 1 byte every 67ns. Of course if your source data was only 4 bits you've already packetized 2 samples!
This brings up an issue again. ethernet is the wrong medium for telemetry within and coming off the rocket. .Ethernet comes in a few versions. EtherCAT and Sercos and things like that have proven super reliable and robust for telemetry and realtime controls in industrial environments. I have no inkling if one of these is being used on GSE
Ethernet comes in a few versions. EtherCAT and Sercos and things like that have proven super reliable and robust for telemetry and realtime controls in industrial environments. I have no inkling if one of these is being used on GSE
So nobody thinks contamination in the lox line could cause this type and magnitude explosion?Yes, many times... ;D
So nobody thinks contamination in the lox line could cause this type and magnitude explosion?
Seems the simplest but suffers from location problems.So nobody thinks contamination in the lox line could cause this type and magnitude explosion?Yes, many times... ;D
And yet another probably irrelevant image processing example.
Here we see a 10 frame sequence, the last frame on the right is frame 0.
The one to the left is Frame-1 minus frame 0, Frame -2 minus frame -1, etc. The differences of 9 frames leading to the last.
the range is maxed with no saturation. Image upscaled X3.
There is no interpretation offered, it looks pretty, but I can't pull any meaning out of it.
No joy on battery locations, but it did get me thinking about the "customer supplied cable 20ft." to pad junction box on the TEL (section 5.1) via the Catenary Umbililcal to S2 (image page 39)... Was that the case for this launch or was it supplied by SpaceX? Was it the first time it was powered on from the TEL junction box?
http://www.spacex.com/sites/spacex/files/falcon_9_users_guide_rev_2.0.pdf
No joy on battery locations, but it did get me thinking about the "customer supplied cable 20ft." to pad junction box on the TEL (section 5.1) via the Catenary Umbililcal to S2 (image page 39)... Was that the case for this launch or was it supplied by SpaceX? Was it the first time it was powered on from the TEL junction box?
http://www.spacex.com/sites/spacex/files/falcon_9_users_guide_rev_2.0.pdf
The "customer supplied cable" could potentially be the source of the ignition, but it could not be the source of the fuel (in the order of 10kg) for the FAE.
And yet another probably irrelevant image processing example.
Here we see a 10 frame sequence, the last frame on the right is frame 0.
The one to the left is Frame-1 minus frame 0, Frame -2 minus frame -1, etc. The differences of 9 frames leading to the last.
the range is maxed with no saturation. Image upscaled X3.
There is no interpretation offered, it looks pretty, but I can't pull any meaning out of it.
Considering the moire patterns you were getting along the length of the Falcon, I think what you invented here is a nice way to show how JPEG compression follows algorithms to create its artifacting... ;)
Jim, do you have a hypothesis?
Without a trace in the telemetry?Jim, do you have a hypothesis?
A pressure/structure event
Without a trace in the telemetry?Jim, do you have a hypothesis?
A pressure/structure event
When does the telemetry start? It was not a real flight, and 8 minutes before the start, so was everything turned on at the time?
Without a trace in the telemetry?Jim, do you have a hypothesis?
A pressure/structure event
Jim, do you have a hypothesis?
A pressure/structure event
Now I do see a serious problem with Jims point A.
There simply is no ice layer on the tank to begin with and no other insulation we'd have heard of. It would take some time for the ice layer to form and the tank would be uninsulated in the meantime. Usually, that cannot possibly be a problem. The LOX is filled in at boiling temperature anyway and there is never any chance at all to condense oxygen from the air.
With subcooled oxygen in the tank, there is a short window of opportunity for oxygen to condense - prior to any ice layer forming on the tank and insulating it.
The cup analogy is really not applicable. There is big difference in thermal mass. Ice should be forming during the chill down. But then again, the loading time is less than 30 minutes
But also, I should have said:
And if there was a risk of LOX forming, then they SHOULD have added insulation. My point is that they would have analyzed this. When liquid air forms on the outside and drains away, it is putting more heat into the tank
I have asked multiples times over the years if SpaceX performs a Nitrogen purge of all the tanks and lines and have never recieved an answer, perhaps this time?
Now I do see a serious problem with Jims point A.
There simply is no ice layer on the tank to begin with and no other insulation we'd have heard of. It would take some time for the ice layer to form and the tank would be uninsulated in the meantime. Usually, that cannot possibly be a problem. The LOX is filled in at boiling temperature anyway and there is never any chance at all to condense oxygen from the air.
With subcooled oxygen in the tank, there is a short window of opportunity for oxygen to condense - prior to any ice layer forming on the tank and insulating it.
The cup analogy is really not applicable. There is big difference in thermal mass. Ice should be forming during the chill down. But then again, the loading time is less than 30 minutes
But also, I should have said:
And if there was a risk of LOX forming, then they SHOULD have added insulation. My point is that they would have analyzed this. When liquid air forms on the outside and drains away, it is putting more heat into the tank
My LIN in an Aluminium cup occurred outside on a reasonably humid warm summers day in Surrey, England.
It doesn't matter if the aluminium LOX container is a small cup or a large pressure vessel. If it is suddenly filled with LIN or super chilled LOX, LOX will form on its surface and drip down and off the bottom on to whatever is below. Even in very humid air, the dripping LOX may even wash away any ice crystals before they have a chance to make contact with and get stuck to the surface of the Aluminium.
However, if as Jim say, the Al/Li tank is pre chill down to say -150°C allowing an ice layer to form before LOX begins to be poured into the 2nd stage, then the surface of the ice will be to warm for LOX to form and drip.....however, during chill down fresh humid air will need to be forcibly convecting around the LOX tank. If the pre chilled tank is simply sitting in stagnant air, all you get is the tiniest layer of ice on the surface surrounded by dehumidified air. A constant flow of new humid air is required to build up the thickness of the layer of ice during pre-chill. Free convection will likely not be good enough.
Insulating by ice build up on the surface sounds like a better option to insulation. Insulation would need to be air tight and vacuumed, as it would quickly become a sponge soaked in LOX if it lost its air tightness.
With respect to LOX compatibility with Aluminium, a couple of decades ago, it was normal for LIN. LOX and LAR be stored in vacuum insulated storage tanks where the inner vessel was made of Aluminium or Stainless Steel. However, there were a few instances of the Aluminium tanks spontaneously exploding for no reason when being filled with clean pure LOX. As the LIN and LAR tanks weren't exploding, the industry made it standard to only fabricate Stainless Steel LOX storage vessels.
The air separation columns that distilled the Oxygen for use in the F9, were likely made of Aluminium. During the air separation process, these columns have hundreds of litres of near pure LOX continuously trickling inside them splashing on top of and through Aluminium packing which is 0.25mm thick aluminium sheet. There are probably a thousand such ASU plants around the world and this thin material never explodes. It is always an aluminium plate fin heat exchanger that has 1mm parting sheets that spontaiously vaporises its self every couple of years. They are assumed to explode due to getting a blockage and build up of solid CO2 and hydrocarbon impurities followed by an impingement of a foreign particle.
The LOX flowing into the F9 is already pureified of hydrocarbons and I can't imagine there is anything in the F9 2nd stage with such thin material and turbulent LOX flow.
If a COPV was the problem, then this would have been identified immediately.
If there was LOX dripping and vaporising, then the GOX sensor would have picked up elevated O2 levels. Maybe an elevated O2 atmosphere is acceptable? After chill down and the ice layer is formed, does the outside surface of the LOX tank have a slow continuous purge with GAN to prevent a high GOX atmosphere from forming at all? This is standard for Cryogenic Air Separation Equipment.
Does the 2nd stage LOX tank have an outer skin with annulus space? If SpaceX don't find the problem, then I predict they will introduce Nitrogen Purging around the LOX tank as a precaution.
If the pre chilled tank is simply sitting in stagnant air, all you get is the tiniest layer of ice on the surface surrounded by dehumidified air. A constant flow of new humid air is required to build up the thickness of the layer of ice during pre-chill. Free convection will likely not be good enough.
So nobody thinks contamination in the lox line could cause this type and magnitude explosion?
It would have happened at the beginning of the load.
Hydrazine is not feasible. It would have gone off in the fairing
Nice to see your personal and professional experience jibes with my engineering intuition.
So assuming an external fuel/air explosive event, any ideas how enough fuel could or would rise the 10' or so from the the apparently-unpressurized RP1 umbilicals? If RP1 loading was complete but the tank not yet at flight pressure, how does that happen? Could a check valve in the RP1 QD have failed, combined with a hole in the umbilical causing a vertical spray or mist up in the clouds of venting O2 gas?
I just don't get the mechanism yet.
I'm struggling with the fact that I've read that Kerosene vapors are heavier than air.
So nobody thinks contamination in the lox line could cause this type and magnitude explosion?
It would have happened at the beginning of the load.
Not if the contamination was inside the tank near the top.
still packeting is good for losing data
NASA seemed to also have concerns on SpaceX telemetry
https://forum.nasaspaceflight.com/index.php?topic=40621.msg1554985#msg1554985
SpaceX has about 3000 total channels, this was communicated by them on other occasions, so I suppose mentioning the number is just a generic way of saying "we have a lot of it" without specifying more.
Discussion on how telemetry is done took place during CRS-7 event when Elon mentioned trying to reconstruct the last frame available. Some starting points should avoid rehashing:
https://forum.nasaspaceflight.com/index.php?topic=37476.msg1398608#msg1398608
https://forum.nasaspaceflight.com/index.php?topic=37954.msg1402048#msg1402048
https://forum.nasaspaceflight.com/index.php?topic=37476.msg1398972#msg1398972
Does the 2nd stage LOX tank have an outer skin with annulus space? If SpaceX don't find the problem, then I predict they will introduce Nitrogen Purging around the LOX tank as a precaution.
So nobody thinks contamination in the lox line could cause this type and magnitude explosion?
It would have happened at the beginning of the load.
Not if the contamination was inside the tank near the top.
If the pre chilled tank is simply sitting in stagnant air, all you get is the tiniest layer of ice on the surface surrounded by dehumidified air. A constant flow of new humid air is required to build up the thickness of the layer of ice during pre-chill. Free convection will likely not be good enough.
From what I saw it was quite windy and very very humid on that day (tropical storm nearby).
I've attempted to draw the internals of the second stage based both on the Falcon 9 User Manual
(http://www.spacex.com/sites/spacex/files/falcon_9_users_guide_rev_2.0.pdf)
, and earlier diagram from 2008.
(http://selenianboondocks.com/wp-content/uploads/2008/11/s12-11.pdf)
There may be (are) more changes from 2008 to now then I've included in this drawing.
All lengths are estimated from slightly blurry images.
Here's my drawing overlaid on the video...
T-0:09:30 M1D Trim Valve Cyclingand the FAE that occurred in the vicinity of the interstage/MVac. Regarding the interstage, I am assuming that it is quite effectively sealed off from the environment outside of the vehicle. Can anyone verify or disprove this assumption?
T-0:09:15 Stage 1 Helium Topping
T-0:07:45 MVac Fuel Trim Valve Setup
For the first few frames, what was the fuel?
For the first few frames, what was the fuel?
The helium bottles are made out of carbon-epoxy, which burns quite aggressively in pure oxygen environments.
For the first few frames, what was the fuel?
The helium bottles are made out of carbon-epoxy, which burns quite aggressively in pure oxygen environments.
Arrh, now I understand the COPV idea. But the ignition method is still unknown and the telemetry would clearly show them rupturing.
It's basically swampland. You're not going to get a surface wave, period.When I witnessed launches at KSC and the Cape, sometimes from less than 3 miles distant, I could feel the ground move beneath my feet before the sound of the launch arrived. Isn't that a "surface wave"?
- Ed Kyle
The question that keeps replaying in my mind is why are the asking for sources of external events? That would mean they have decided that the vehicle is a sound design and played no responsibility in the mishap. Just thinking out loud on my keyboard...
There have been multiple times in Mojave when we would fill an uninsulated steel sphere with LN2. It would rapidly form an ice layer even in non-windy, low humidity conditions. The "ice" that forms is more like snow however, and is usually 1/4" to 3/8" thick. We wanted the LN2 to boil, so we would brush off the snow every few minutes. I don't remember liquid air ever forming; it would just start making more snow. I think the densified LOX on the Falcon 9 is warmer than LN2, so doubt air would condense on the outside.
1. Wouldn't the vents be somewhat one way? That and gravity might be enough to prevent it going internal to the fairing.
2. Plus there would be no oxidizer in the fairing if only the "fuel" part was leaking.
3. So two questions: Would the payload have been monitored AT ALL during the static fire?
4 Is Hydrazine hypergolic in oxygen enriched air?
1. No, they just have air blowing out them
2. Not needed. See below
3. Yes,
4. Hydrazine is a monopropellant, it needs no oxygen. It reacts with many items. Rust, dirt, foam, etc can set it off.
The SpaceX explosion highlights a backend way to invest in the space...... by investing in the launch insurance business.
... Thus the loss of the rocket is a $250M plus hit – and that’s where the opportunity comes in. Such losses highlight the importance of risk mitigation through insurance – and the space insurance industry is one that investors can invest in.... which profits from the sustained need for insurance.
For SpaceX to have an insurance policy they must pay a premium to big name insurance companies like AIG, Allianz, AON, or XL Catlin. Last year there were $500 million in claims; double the premiums being paid.... premium costs don't just gradually rise.
... all it takes is 2 to 3 explosions a year for the insurance market to run into trouble – such problems can actually be a good thing. Typically, in catastrophe insurance markets, whether it is hurricanes or rocket explosions, a bad year leads to a good year. In bad years, some players exit the market, and everyone raises premium prices. That typically leads to a strong follow-up year in which the industry is more profitable thanks to higher prices.... because the increased premiums stay with you for follow-on years.
With an increase in annual launches there is a high likelihood of rocket explosions becoming even more numerous. These commercial space companies will feel a greater need to insure their rockets and their payloads, increasing the demand for insurance policies. By investing in insurers like AON or XL Catlin, companies that protect these rockets, investors can see a correlation between returns and development of the space industry, predominantly private.... launch frequency means potential casualties must rise. Actually, the profitability of such insurance grows faster than the profitability of launches ... irrespective of success.
I do NOT subscribe to the sabotage theories, but as outside interference has not yet been ruled out, perhaps they will need to borrow some techniques from aircraft crash investigation; ie microscopic examination of salvaged parts of the external hull for explosives residue and pitting from high velocity impact (implying high detonation velocity). Another would be partial reconstruction of the hull to demonstrate that the initial explosion was definitively outside the F9 (ie, the panels all buckled inwards). Would also allow higher precision in determining the initiation point.The problem is that aluminum and aluminum lithium melts at about 1,200 F or less. This fire likely generated higher temperatures than that. Much of the metal fuselage likely melted into silver blobs.
...
Having most of the pieces available for this sort of investigation will be useful, and finding a bullet hole would of course simplify things immensely!
The question that keeps replaying in my mind is why are the asking for sources of external events? That would mean they have decided that the vehicle is a sound design and played no responsibility in the mishap. Just thinking out loud on my keyboard...
The T/E is still standing.I'm not surprised. The hydraulics are probably destroyed so either they'll have to replace the entire hydraulic system for T/E or they'll have to rent some mobile cranes to manually rotate it back to a horizontal position.
Yes, this is what has been plaguing me re: the sounds for a while now. There's no way to tell whether or not the sounds actually came from the pad or the vehicle. We do know for a fact that SpaceX do have at least one microphone at the pad, so if it didn't record the noises I seriously doubt that it came from either the pad or the vehicle.The question that keeps replaying in my mind is why are the asking for sources of external events? That would mean they have decided that the vehicle is a sound design and played no responsibility in the mishap. Just thinking out loud on my keyboard...
Because different audio recordings taken from different distances/locations would help them determine whether the "precursor" sounds came from the rocket/pad, or were an artifact from near the camera.
Right now the only audio recording we have is the USLaunchReport video, and it's unclear whether the precursor sounds came from the rocket or from the junkyard where the camera was. If a different audio recording from another spot at the Cape also has the precursor sounds with the same time differential, that would suggest they came from the rocket/pad rather than the junkyard.
This brings up an issue again. ethernet is the wrong medium for telemetry within and coming off the rocket. packetization means data can be lost in incidents such as this. And timing can get screw up. Serial data rules for these instances.
Loss is not a given on switched ethernet. Also the minimum frame time at 10Gbps is only 67 nanoseconds. At level, the amount of time it takes your operating system to finish an interrupt will be the driving factor in timing.
still packeting is good for losing data
On reddit is a thread investigating the audio recording from the video. It seems that the camera had a stereo microphone. According to the redditor, the mystery sound came from a different direction than the explosion and is probably unrelated to the fireball.The question that keeps replaying in my mind is why are the asking for sources of external events? That would mean they have decided that the vehicle is a sound design and played no responsibility in the mishap. Just thinking out loud on my keyboard...
Because different audio recordings taken from different distances/locations would help them determine whether the "precursor" sounds came from the rocket/pad, or were an artifact from near the camera.
Right now the only audio recording we have is the USLaunchReport video, and it's unclear whether the precursor sounds came from the rocket or from the junkyard where the camera was. If a different audio recording from another spot at the Cape also has the precursor sounds with the same time differential, that would suggest they came from the rocket/pad rather than the junkyard.
This brings up an issue again. ethernet is the wrong medium for telemetry within and coming off the rocket. packetization means data can be lost in incidents such as this. And timing can get screw up. Serial data rules for these instances.
Loss is not a given on switched ethernet. Also the minimum frame time at 10Gbps is only 67 nanoseconds. At level, the amount of time it takes your operating system to finish an interrupt will be the driving factor in timing.
still packeting is good for losing data
Disagree. I concur with dbavatar. Your experience may be based on a misbehaving link technology or oversubscribed switches.
There are link bit errors and switches dropping packets. Serial lines aren't going to help reduce link bit error rate, that comes down to whatever technology you are using for transmission. Raw serial lines do pass the glitchy data up to your software, so presumably you could do better error containment there. Packet switched stuff will just dump the whole packet when there is a bit error, which potentially amplifies the underlying bit error rate.
I believe Jim is simply saying that if you wait x ms to assemble a packet of data (packetise) before you transmit it, you will lose up to x ms of untransmitted data when an event occurs.Packetization before transmitting is not really happening in hard-realtime industrial ethernet versions. Look up IEC 61158 / EtherCAT
Please don't take this as a snarky answer, but to say the cause "is" from coincidental ambient sounds is a little surprising from them this early in the investigation... Shuttle flew for thirty years and they were still discovering new things about her and retrospectively deemed it an "experimental" vehicle in an operational role... I was one of the many "so called foamologists" as was termed by the then NASA administrator Sean O'Keefe after the Columbia accident. Prior to the report, I had my physics student calculate the energy and forces of a strike from simple first principals would be enough to cause damage to RCC. The point I am making is to not go down the road of being in denial of the "fragility" of an experimental system with all the new processes they are using...The question that keeps replaying in my mind is why are the asking for sources of external events? That would mean they have decided that the vehicle is a sound design and played no responsibility in the mishap. Just thinking out loud on my keyboard...
Because different audio recordings taken from different distances/locations would help them determine whether the "precursor" sounds came from the rocket/pad, or were an artifact from near the camera.
Right now the only audio recording we have is the USLaunchReport video, and it's unclear whether the precursor sounds came from the rocket or from the junkyard where the camera was. If a different audio recording from another spot at the Cape also has the precursor sounds with the same time differential, that would suggest they came from the rocket/pad rather than the junkyard.
The question that keeps replaying in my mind is why are the asking for sources of external events? That would mean they have decided that the vehicle is a sound design and played no responsibility in the mishap. Just thinking out loud on my keyboard...
I do NOT subscribe to the sabotage theories, but as outside interference has not yet been ruled out, perhaps they will need to borrow some techniques from aircraft crash investigation; ie microscopic examination of salvaged parts of the external hull for explosives residue and pitting from high velocity impact (implying high detonation velocity).
Right now the only audio recording we have is the USLaunchReport video, and it's unclear whether the precursor sounds came from the rocket or from the junkyard where the camera was. If a different audio recording from another spot at the Cape also has the precursor sounds with the same time differential, that would suggest they came from the rocket/pad rather than the junkyard.
Was it simply hugged too much, or too little.
Please don't take this as a snarky answer, but to say the cause "is" from coincidental ambient sounds is a little surprising from them this early in the investigation... Shuttle flew for thirty years and they were still discovering new things about her...The question that keeps replaying in my mind is why are the asking for sources of external events? That would mean they have decided that the vehicle is a sound design and played no responsibility in the mishap. Just thinking out loud on my keyboard...
Because different audio recordings taken from different distances/locations would help them determine whether the "precursor" sounds came from the rocket/pad, or were an artifact from near the camera.
Right now the only audio recording we have is the USLaunchReport video, and it's unclear whether the precursor sounds came from the rocket or from the junkyard where the camera was. If a different audio recording from another spot at the Cape also has the precursor sounds with the same time differential, that would suggest they came from the rocket/pad rather than the junkyard.
BingoThe question that keeps replaying in my mind is why are the asking for sources of external events? That would mean they have decided that the vehicle is a sound design and played no responsibility in the mishap. Just thinking out loud on my keyboard...
Because different audio recordings taken from different distances/locations would help them determine whether the "precursor" sounds came from the rocket/pad, or were an artifact from near the camera.
Right now the only audio recording we have is the USLaunchReport video, and it's unclear whether the precursor sounds came from the rocket or from the junkyard where the camera was. If a different audio recording from another spot at the Cape also has the precursor sounds with the same time differential, that would suggest they came from the rocket/pad rather than the junkyard.
So nobody thinks contamination in the lox line could cause this type and magnitude explosion?
It would have happened at the beginning of the load.
Not if the contamination was inside the tank near the top.
Yeah, but the specific question he was responding to was about contamination in the LOX line (or maybe at the GSE/vehicle interface), and I assume propagating into the tank during LOX loading operations. Jim's point was that in that scenario, the anomaly would be expected to occur at the beginning of the loading This scenario is distinct from contamination having been in the tank prior to filling.
That said, I'm not sure that the expectation would be all that different. A good amount of the LOX that is loaded at the very beginning will boil off while the tank is chilling down. So, you end up with quite a bit of GOX in the tank early in the fill operation and it is in contact with the contamination at the top of the tank. Not sure I see much of a difference besides maybe the hydrodynamics of the LOX, but I'm not an expert.
Is there any estimation how much fuel,lox,contamination... is needed for an initial ignition of the observed size (or needed size to trigger the observed RUD)? I would expect such an amount estimation, say for fuel aerosol, would give some hints on the timing as it may need som time to build up. Any expert for a hint on this here?I have seen somewhere on this thread of about a gallon of rp1 necessary for the initial explosion(that was for FAE).
Yes, Hydrazine is a monopropellant. The problem with that line of thinking is that the payload didn't have hydrazine. It had UDMH (which, yes - is a hydrazine derivative, but not "hydrazine")
This arrangement could make sure the patches of tank were clear of ice and impart a varying, and sliding load to the skin.
There is also I believe a vent around that point for oxygen. The wind direction would carry the output to the rocket skin.
Was that enough to crack the skin exposing the fresh metal to oxygen and forming the initial fire. The rest is inevitable.
This brings up an issue again. ethernet is the wrong medium for telemetry within and coming off the rocket. packetization means data can be lost in incidents such as this. And timing can get screw up. Serial data rules for these instances.
Loss is not a given on switched ethernet. Also the minimum frame time at 10Gbps is only 67 nanoseconds. At level, the amount of time it takes your operating system to finish an interrupt will be the driving factor in timing.
still packeting is good for losing data
Disagree. I concur with dbavatar. Your experience may be based on a misbehaving link technology or oversubscribed switches.
F9 is a clean sheet design, and being able to get the last bit of data out is a design requirement for telemetry...j
In light of the appeal this is my $0.02 worth.
There are only two observable differences with this flight and any other.
1. The satellite
2. The wind and direction
]
Loss is not a given on switched ethernet. Also the minimum frame time at 10Gbps is only 67 nanoseconds. At level, the amount of time it takes your operating system to finish an interrupt will be the driving factor in timing.
This brings up an issue again. ethernet is the wrong medium for telemetry within and coming off the rocket. packetization means data can be lost in incidents such as this. And timing can get screw up. Serial data rules for these instances.
Loss is not a given on switched ethernet. Also the minimum frame time at 10Gbps is only 67 nanoseconds. At level, the amount of time it takes your operating system to finish an interrupt will be the driving factor in timing.
still packeting is good for losing data
Disagree. I concur with dbavatar. Your experience may be based on a misbehaving link technology or oversubscribed switches.
There are link bit errors and switches dropping packets. Serial lines aren't going to help reduce link bit error rate, that comes down to whatever technology you are using for transmission. Raw serial lines do pass the glitchy data up to your software, so presumably you could do better error containment there. Packet switched stuff will just dump the whole packet when there is a bit error, which potentially amplifies the underlying bit error rate.
With gigabit ethernet over cat5, I found a consistent bit error rate of 3e-12. With 10GbE over multimode fiber, I never saw a single bit error ever. We ran a test for weeks, probably over a month (we forgot about it for a while), with an FPGA stuffing packets down the fiber with minimum interpacket gaps. No errors. That's better than 1e-16 BER!
<Snip>A most interesting first post. Anyone able to refute it?
Now back to the wind. The discussions on oxygen condensation all show that the ice would form first. Yet there is one point this would not be true. This strong back is unique in having a pivoted cradle for the upper stage. This means the grabbers hold predominantly the far side of the cylinder. The pivoting cradle pushes on the near side, to the strongback. I have been unable to locate any hydraulics associated with this pivoting cradle from images or videos.
If gravity does its job, the cradle would push more on the upper support than the lower one. This would be countered by the grabbers. In an early video of the strongback retraction a previous Falcon 9 is seen to sway significantly. The grabbers must therefore have enough force to hold it. If they are slack the pivoting cradle will modulate its push, with the wind caused flexing, on the lower support. The wind direction is pushing the Falcon 9 away from the strongback. Every time the wind gusts the lower cradle would ease off the pressure and move up slightly. The pads on the grabbers are on the sides and the far side. How do they regulate the force, do they prioritise squashing it or pulling it back. These are also set while the rocket is horizontal but are used when it is vertical.
This arrangement could make sure the patches of tank were clear of ice and impart a varying, and sliding load to the skin.
There is also I believe a vent around that point for oxygen. The wind direction would carry the output to the rocket skin.
Was that enough to crack the skin exposing the fresh metal to oxygen and forming the initial fire. The rest is inevitable.
In this case there would be no indications on any sensors of any prior event.
If this is the case then the solution was also achieved in the event. The strongback was destroyed. The new designs do not have the same mechanism. They need to grab the Falcon 9 above the tanks with a grabber that has equal angle of pads around the cylinder.
Was it simply hugged too much, or too little.
<Snip>A most interesting first post. Anyone able to refute it?
Now back to the wind. The discussions on oxygen condensation all show that the ice would form first. Yet there is one point this would not be true. This strong back is unique in having a pivoted cradle for the upper stage. This means the grabbers hold predominantly the far side of the cylinder. The pivoting cradle pushes on the near side, to the strongback. I have been unable to locate any hydraulics associated with this pivoting cradle from images or videos.
If gravity does its job, the cradle would push more on the upper support than the lower one. This would be countered by the grabbers. In an early video of the strongback retraction a previous Falcon 9 is seen to sway significantly. The grabbers must therefore have enough force to hold it. If they are slack the pivoting cradle will modulate its push, with the wind caused flexing, on the lower support. The wind direction is pushing the Falcon 9 away from the strongback. Every time the wind gusts the lower cradle would ease off the pressure and move up slightly. The pads on the grabbers are on the sides and the far side. How do they regulate the force, do they prioritise squashing it or pulling it back. These are also set while the rocket is horizontal but are used when it is vertical.
This arrangement could make sure the patches of tank were clear of ice and impart a varying, and sliding load to the skin.
There is also I believe a vent around that point for oxygen. The wind direction would carry the output to the rocket skin.
Was that enough to crack the skin exposing the fresh metal to oxygen and forming the initial fire. The rest is inevitable.
In this case there would be no indications on any sensors of any prior event.
If this is the case then the solution was also achieved in the event. The strongback was destroyed. The new designs do not have the same mechanism. They need to grab the Falcon 9 above the tanks with a grabber that has equal angle of pads around the cylinder.
Was it simply hugged too much, or too little.
Edit: Prune quote.
I have no problem with them looking for an additional data point "if" indeed that is what he means. As far as Shuttle was concerned, NASA folks are the same as the ones at SpaceX, as are us all. We are all humans, subject to biases, making mistakes and sometimes blinded by ambition...Please don't take this as a snarky answer, but to say the cause "is" from coincidental ambient sounds is a little surprising from them this early in the investigation... Shuttle flew for thirty years and they were still discovering new things about her...The question that keeps replaying in my mind is why are the asking for sources of external events? That would mean they have decided that the vehicle is a sound design and played no responsibility in the mishap. Just thinking out loud on my keyboard...
Because different audio recordings taken from different distances/locations would help them determine whether the "precursor" sounds came from the rocket/pad, or were an artifact from near the camera.
Right now the only audio recording we have is the USLaunchReport video, and it's unclear whether the precursor sounds came from the rocket or from the junkyard where the camera was. If a different audio recording from another spot at the Cape also has the precursor sounds with the same time differential, that would suggest they came from the rocket/pad rather than the junkyard.
Not quite sure I understand your post. But it seems SpaceX hasn't yet concluded whether those precursor sounds *are* causal or unrelated, which is why they're asking for more audio. If I understand Elon's tweet, vehicle sensors (ie high freq accelerometers) didn't pick up the precursor sounds, which would suggest they didn't originate in the vehicle. But they are being extra cautious by asking for more audio in order to try to pinpoint where those sounds did come from. Which means, unlike the NASA shuttle foam debacle, they aren't making the mistake of ignoring evidence that could be overlooked or prematurely dismissed as unrelated.
Is there any estimation how much fuel,lox,contamination... is needed for an initial ignition of the observed size (or needed size to trigger the observed RUD)? I would expect such an amount estimation, say for fuel aerosol, would give some hints on the timing as it may need som time to build up. Any expert for a hint on this here?I have seen somewhere on this thread of about a gallon of rp1 necessary for the initial explosion(that was for FAE).
Of course if a lox line explodes from contamination it takes what ever the tubing material is(Al?) with it.
My other problem with external lox line exploding is that the center of the initial explosion is not where the lox lines are.
Yes, Hydrazine is a monopropellant. The problem with that line of thinking is that the payload didn't have hydrazine. It had UDMH (which, yes - is a hydrazine derivative, but not "hydrazine")
Neither UDMH or Aerozine 50 are not used by spacecraft. It is a launch vehicle propellant. MMH or Hydrazine is used in spacecraft for the liquid apogee engine but hydrazine is use for attitude control thrusters
Neither UDMH or Aerozine 50 have been present at the Cape since the last Titan IV
re the cradle, see Reply #1717 this thread.
clearly shows the hydraulics. Later in that thread is a closeup.
This arrangement could make sure the patches of tank were clear of ice and impart a varying, and sliding load to the skin.
There is also I believe a vent around that point for oxygen. The wind direction would carry the output to the rocket skin.
Was that enough to crack the skin exposing the fresh metal to oxygen and forming the initial fire. The rest is inevitable.
Will such cracking result in the observed large and fast initial explosion? I doubt it.
No, my experience is with launch vehicle failuresstill packeting is good for losing dataDisagree. I concur with dbavatar. Your experience may be based on a misbehaving link technology or oversubscribed switches.
Do we have hard confirmation whether the fairing/payload was nitrogen purged? It is listed as an option in the F9 user's guide.
No, my experience is with launch vehicle failuresstill packeting is good for losing dataDisagree. I concur with dbavatar. Your experience may be based on a misbehaving link technology or oversubscribed switches.
So other launch vehicles have used packeting? What did the shuttle use?
1. A tank full of densitied LOX doesn't need to have a leak or vented oxygen in order for their to be a high oxygen concentration on the outside. It's more than sufficient to liquefy air, and in the right conditions, a predominantly liquid oxygen mixture. This is a risk that does not exist with boiling-point LOX.
2. What exactly do they paint with? Most organics (with the exception of some fluorinated ones, which would be too expensive for paint) and silicone compounds are impact and heat sensitive when in contact with LOX.
As a general rule one *strongly* tries to avoid air liquefaction around rockets. Does SpaceX do anything at all to prevent it?
A note that if the actual problem was due to air liquefaction... there's no easy fix for this, at least not one that doesn't ruin performance.
clearly shows the hydraulics. Later in that thread is a closeup.
1. A tank full of densified LOX doesn't need to have a leak or vented oxygen in order for their to be a high oxygen concentration on the outside. It's more than sufficient to liquefy air, and in the right conditions, a predominantly liquid oxygen mixture. This is a risk that does not exist with boiling-point LOX.
2. What exactly do they paint with? Most organics (with the exception of some fluorinated ones, which would be too expensive for paint) and silicone compounds are impact and heat sensitive when in contact with LOX.
As a general rule one *strongly* tries to avoid air liquefaction around rockets. Does SpaceX do anything at all to prevent it?
A note that if the actual problem was due to air liquefaction... there's no easy fix for this, at least not one that doesn't ruin performance.
That isn't the problem. There is ice on the stages.
Less Land (who brought up this particular topic) was arguing for conditions that could shed ice. Which isn't a far-fetched concept.
Welcome to the forum! :) I have looking for a few days now and only located the two rams as well...
re the cradle, see Reply #1717 this thread.
clearly shows the hydraulics. Later in that thread is a closeup.
It shows the two large rams for the grabbers. I can find no other rams to control the pivoting cradle. The internship video has a good close up.
The article you cite, plus other sources, state that AMOS-6 was equipped with an Airbus S400 Series Apogee motor which uses MMH and MON as Bipropellants.
Yes, Hydrazine is a monopropellant. The problem with that line of thinking is that the payload didn't have hydrazine. It had UDMH (which, yes - is a hydrazine derivative, but not "hydrazine")
Neither UDMH or Aerozine 50 are not used by spacecraft. It is a launch vehicle propellant. MMH or Hydrazine is used in spacecraft for the liquid apogee engine but hydrazine is use for attitude control thrusters
Neither UDMH or Aerozine 50 have been present at the Cape since the last Titan IV
Looks like I was wrong about UDMH on the payload, so I did some more digging. This is a reference to AMOS-6 using MMH for the propellant
http://spaceflight101.com/falcon-9-amos-6/amos-6-satellite/
I can't find any reference to MMH as a monopropellant. It is (like UDMH) notably more stable than straight hydrazine.
Flash point (in air) of -8C
Autoignition temperature of 196C
Flammable limits (in air) of 2.5-92%
Compare to UDMH
Flash point (in air) of -10C
Autoignition temperature of 248C
Flammable limits (in air) of 2-95%
Characteristics are quite similar.
The article further states that station keeping was to be achieved using a Thales Alenia Electric propulsion system, so there may well have been no separate pure Hydrazine loaded aboard to drive a monopropellant attitude control system.
Less Land (who brought up this particular topic) was arguing for conditions that could shed ice. Which isn't a far-fetched concept.
it is farfetched.
No, my experience is with launch vehicle failuresstill packeting is good for losing dataDisagree. I concur with dbavatar. Your experience may be based on a misbehaving link technology or oversubscribed switches.
So other launch vehicles have used packeting? What did the shuttle use?
Shuttle existed long before ethernet
Less Land (who brought up this particular topic) was arguing for conditions that could shed ice. Which isn't a far-fetched concept.
it is farfetched.
It's worth pointing out that the reason LH tanks need insulation and LOX tanks don't is precisely that: air liquefaction. It's not simply "hydrogen is cold so it loses heat fast"; it's "hydrogen is cold enough to liquefy air which draws away heat *far* faster than would otherwise occur". And "ice" isn't enough to protect it from air liquefaction, you need real insulation.
No, densified LOX is not as cold as hydrogen. But it's still extremely cold - what, ~23C colder than boiling-point LOX? The thermal conductivity of water ice is 2.2W/m², compared to typical foam insulations at around 0.03W/m² . It's just not that good of an insulator.
And that's assuming it even stays on. Or has sufficient time to form to a relevant thickness, when they're just starting loading.
I like ideas that have to do with the temperature, since the flight history of that configuration is much shorter.
Might be interesting to look at the Field Mill data on that date and time...I like ideas that have to do with the temperature, since the flight history of that configuration is much shorter.
Before this even happened, my though was "they are very brave to do static test in tropical storm conditions". Weather on this day was really bad.
Depends on your definition of long. Space shuttle design started in the early 70, 1972 was the launch date. First flight in 1981. Ethernet gestation was around the same time, at Xerox Parc, in 1973/4. First standard was 1983, although commercially introduced in 1980, before the first shuttle flight.
Less Land (who brought up this particular topic) was arguing for conditions that could shed ice. Which isn't a far-fetched concept.
it is farfetched.
The concept of ice shedding, off of smooth, freshly painted aluminum, on a substrate that's undergoing thermal expansion, uneven thermal expansion at that, and is a tall object subjected to time-varying wind and propellant loadings.... is far fetched? In what world?
Glenn Thompson posted the data from his infrasound station near the pad on Twitter:
https://twitter.com/volcanoglenn/status/774724624655519744
Glenn Thompson posted the data from his infrasound station near the pad on Twitter:
https://twitter.com/volcanoglenn/status/774724624655519744
Assuming seismographs are located near the Lighthouse and assuming "U" on this chart represents the bang Musk was talking about, it is 4.5 seconds before explosion happens. Does it mean source of this bang was a few hounded yards south of the pad?
Glenn Thompson posted the data from his infrasound station near the pad on Twitter:
https://twitter.com/volcanoglenn/status/774724624655519744
Assuming seismographs are located near the Lighthouse and assuming "U" on this chart represents the bang Musk was talking about, it is 4.5 seconds before explosion happens. Does it mean source of this bang was a few hounded yards south of the pad?
In that tweet he says the top three traces were from ultrasound sensors arranged in a triangle 0.87 mi from the pad. But only one of the (co-located) sensors shows the "U" artifact, so I'm not sure what we can conclude from it.
1. EXACTLY at what time in the countdown did this event occur? If this is not known, why isn't it?
2. WHERE is most likely location where the event initiated?
3. Is TEA-TAB for the second stage loaded prior to erection or while on the pad? I see mention of TEA-TAB in the countdown timeline.
3. Where are SpaceX pad cameras located?
Glenn Thompson posted the data from his infrasound station near the pad on Twitter:
https://twitter.com/volcanoglenn/status/774724624655519744
Assuming seismographs are located near the Lighthouse and assuming "U" on this chart represents the bang Musk was talking about, it is 4.5 seconds before explosion happens. Does it mean source of this bang was a few hounded yards south of the pad?
In that tweet he says the top three traces were from ultrasound sensors arranged in a triangle 0.87 mi from the pad. But only one of the (co-located) sensors shows the "U" artifact, so I'm not sure what we can conclude from it.
In this case the source of this bang is much closer to LC-40. If we knew exactly where these seismographs were located we could perform some crude triangulation to find two possible locations of this bang.
This arrangement could make sure the patches of tank were clear of ice and impart a varying, and sliding load to the skin.
There is also I believe a vent around that point for oxygen. The wind direction would carry the output to the rocket skin.
Was that enough to crack the skin exposing the fresh metal to oxygen and forming the initial fire. The rest is inevitable.
Will such cracking result in the observed large and fast initial explosion? I doubt it.
Some notes.
1. A tank full of densified LOX doesn't need to have a leak or vented oxygen in order for their to be a high oxygen concentration on the outside. It's more than sufficient to liquefy air, and in the right conditions, a predominantly liquid oxygen mixture. This is a risk that does not exist with boiling-point LOX.
2. What exactly do they paint with? Most organics (with the exception of some fluorinated ones, which would be too expensive for paint) and silicone compounds are impact and heat sensitive when in contact with LOX.
As a general rule one *strongly* tries to avoid air liquefaction around rockets. Does SpaceX do anything at all to prevent it?
A note that if the actual problem was due to air liquefaction... there's no easy fix for this, at least not one that doesn't ruin performance.
The article you cite, plus other sources, state that AMOS-6 was equipped with an Airbus S400 Series Apogee motor which uses MMH and MON as Bipropellants.
Yes, Hydrazine is a monopropellant. The problem with that line of thinking is that the payload didn't have hydrazine. It had UDMH (which, yes - is a hydrazine derivative, but not "hydrazine")
Neither UDMH or Aerozine 50 are not used by spacecraft. It is a launch vehicle propellant. MMH or Hydrazine is used in spacecraft for the liquid apogee engine but hydrazine is use for attitude control thrusters
Neither UDMH or Aerozine 50 have been present at the Cape since the last Titan IV
Looks like I was wrong about UDMH on the payload, so I did some more digging. This is a reference to AMOS-6 using MMH for the propellant
http://spaceflight101.com/falcon-9-amos-6/amos-6-satellite/
I can't find any reference to MMH as a monopropellant. It is (like UDMH) notably more stable than straight hydrazine.
Flash point (in air) of -8C
Autoignition temperature of 196C
Flammable limits (in air) of 2.5-92%
Compare to UDMH
Flash point (in air) of -10C
Autoignition temperature of 248C
Flammable limits (in air) of 2-95%
Characteristics are quite similar.
The article further states that station keeping was to be achieved using a Thales Alenia Electric propulsion system, so there may well have been no separate pure Hydrazine loaded aboard to drive a monopropellant attitude control system.
1. Why?
2. The summary of the most likely sources mentioned so far by someone who HAS read the entire very long thread would be useful for everyone else.
3. A simple yes/no answer is all that question requires.
4. I'd certainly hope there's one in the umbilical area and some locations can be known through recollections of individuals who have watched their YouTube launch coverage. Anyone ever seen one from the umbilical area?
1. Why?
2. The summary of the most likely sources mentioned so far by someone who HAS read the entire very long thread would be useful for everyone else.
3. A simple yes/no answer is all that question requires.
4. I'd certainly hope there's one in the umbilical area and some locations can be known through recollections of individuals who have watched their YouTube launch coverage. Anyone ever seen one from the umbilical area?
1. Ask Spacex
2. And we would have to do that for everybody that comes late to the party
3. It is not known
4. Spacex doesn't release close range camera views of the vehicle.
IIRC the 3 stage solid Pegasus and Pegasus XL have used Ethernet for internal functions since their first launch.Depends on your definition of long. Space shuttle design started in the early 70, 1972 was the launch date. First flight in 1981. Ethernet gestation was around the same time, at Xerox Parc, in 1973/4. First standard was 1983, although commercially introduced in 1980, before the first shuttle flight.
Long as in regular usage. Airplanes didn't even use it for a long time. Shuttle didn't even use it for PC's in the cabin until the later 90's.
IIRC the 3 stage solid Pegasus and Pegasus XL have used Ethernet for internal functions since their first launch.
The other potential issue is items not being synchronized due to delays between when a channel is sampled and when it's sent. While Ethernet cannot supply a pure set of data values exactly when they happen (as a 3000 pin plug could) but the greater data rate would if necessary allow every channel to be time tagged.Modern Ethernet provides for precision timestamping, frequency and phase synchronisation down to 500ns (or even better in a small network). Developing these capabilities was required as Ethernet has become a de-facto (=cheap!) backhaul medium in mobile networks, especially with recent LTE-A introduction. This is all way beyond what was available 5-10 years ago, not to mention technology origins.
(http://uploads.tapatalk-cdn.com/20160911/69fad97ab9681f6943e99f7bff5faa8a.jpg)
Not sure if I missed this being mentioned or discussed. Is this of any value? Can the source of the thump triangulated with this info?
Edit: just found it few posts back. Searched for seismic and found nothing. Should have searched for Thompson.
Mods: feel free to remove this post
Here are the positions for Glenn Thompson's sensors:
https://www.google.com/maps/d/viewer?mid=17Tim56aFrQKtcF2KStP05hG9A3M
The one that recorded the blip before the main event is located NNW of the pad between SLC 40 and 41.
-C
Edit: The data that I'm really interested in is the "pop" on the top channel at 13:07:11.
The other potential issue is items not being synchronized due to delays between when a channel is sampled and when it's sent. While Ethernet cannot supply a pure set of data values exactly when they happen (as a 3000 pin plug could) but the greater data rate would if necessary allow every channel to be time tagged.Modern Ethernet provides for precision timestamping, frequency and phase synchronisation down to 500ns (or even better in a small network). Developing these capabilities was required as Ethernet has become a de-facto (=cheap!) backhaul medium in mobile networks, especially with recent LTE-A introduction. This is all way beyond what was available 5-10 years ago, not to mention technology origins.
Nevertheless Ethernet or not is a secondary consideration, primary is how SpaceX wanted to perform the whole data multiplexing (delay/resilience/...).
Here are the positions for Glenn Thompson's sensors:
https://www.google.com/maps/d/viewer?mid=17Tim56aFrQKtcF2KStP05hG9A3M
The one that recorded the blip before the main event is located NNW of the pad between SLC 40 and 41.
-C
Edit: The data that I'm really interested in is the "pop" on the top channel at 13:07:11.
I would love to know why only one of these three sensors registered the event. Tuned to different frequencies?
This is the sound track from the video and the seismic data scaled and aligned as I personally think makes sense. :)
This is the sound track from the video and the seismic data scaled and aligned as I personally think makes sense. :)
This is the sound track from the video and the seismic data scaled and aligned as I personally think makes sense. :)
Sure, anyone is free to use it as they wish.This is the sound track from the video and the seismic data scaled and aligned as I personally think makes sense. :)
RDoc, do you mind if I cross-post your stacked graphs of the sonic and seismic data over on the FB @SpaceX group?
This is the sound track from the video and the seismic data scaled and aligned as I personally think makes sense. :)
This is amazing! Plus it seems to show the initial "bang" originated outside of the pad.
This is the sound track from the video and the seismic data scaled and aligned as I personally think makes sense. :)
This is amazing! Plus it seems to show the initial "bang" originated outside of the pad.
Well, if his alignment is correct, you'll note that the initial bang doesn't create much of a seismic signal, in which case, it doesn't tell us much about where the clang and thunk came from unless they came from the "debris hit the ground" phase with different P & S arrival times. Which is possible since that occurs prior to the clang and thunk.
BUT, it would require recalculating the speed of sound in the ground.
The other potential issue is items not being synchronized due to delays between when a channel is sampled and when it's sent. While Ethernet cannot supply a pure set of data values exactly when they happen (as a 3000 pin plug could) but the greater data rate would if necessary allow every channel to be time tagged.Modern Ethernet provides for precision timestamping, frequency and phase synchronisation down to 500ns (or even better in a small network). Developing these capabilities was required as Ethernet has become a de-facto (=cheap!) backhaul medium in mobile networks, especially with recent LTE-A introduction. This is all way beyond what was available 5-10 years ago, not to mention technology origins.
Nevertheless Ethernet or not is a secondary consideration, primary is how SpaceX wanted to perform the whole data multiplexing (delay/resilience/...).
With event propagation measured in maybe 1000 m/sec, and structural scale of 1 m, you're looking at 1 mSec desired latency.
That is a huge huge time for electronics, where you can package frames in uSecs.
The concern with "original" Ethernet was that you had multiple devices on a coax cable, and stochastic collision resolution, and so in principle a data packet may be held indefinitely before leaving the source. Total bandwidth back then was 10 Mb/sec, which only applied in theory if one device was talking the whole time.
This is all history, however. Applicable to vehicles that started development 20-30 years ago.
To confirm the pivoting cradle is free to move, look at the technical webcast for CRS-8. Look at the internship video at 3:35 for a close up.
At 4:10, on the countdown clock for CRS-8, there is a close up. Look at the square sections behind the grabbers as they release. This is the top of the pivoting cradle. As the grabbers release the cradle falls forward while the strongback falls away.
What happens in high winds blowing the Falcon 9 away from the strongback?
The grabbers are not rigid so will allow the Falcon 9 to move away. If this movement is enough to allow the lower pivoting cradle to separate from the tank then all manner of mechanisms could occur.
1. For large gaps the snow would form behind the pad and then be crushed on the next sway. This would form ice that is not thermally insulating. So the next sway would form more snow and then ice. A build up would occur. "Snow" can easily be 90% trapped air and compares well with good insulation. Ice is much worse. The pads pivot also. Would one end become thick with ice and create a point load?
2. Bouncing cold metals is just bad. Bouncing welds even more of a problem.
3. In a tiny gap situation the water would be condensed rapidly at the outer edges of the pad and only the dry air would get to the centre of the pad. The pad would provide insulation and wind shielding to lower the temperature behind its centre. This would lead to trapped condensation of oxygen plus repetitive loading/rubbing.
My experience is from corrosion of metals including aluminium in a sea environment. Similar situations occur with salt build up between moving items in a high sea spray environment. Same occurs with ice build up, but I make sure I never get any experience of that! Stainless tanks splitting after constant sloshing. Aluminium erosion by even the softest natural materials constantly rubbing. Crevice corrosion of stainless steel which is the opposite situation were damage is done due to oxygen starvation in narrow areas. All metals have to be treated fairly to gain their advantage. Any discontinuity in environment is always bad news.
(http://uploads.tapatalk-cdn.com/20160911/69fad97ab9681f6943e99f7bff5faa8a.jpg)
Not sure if I missed this being mentioned or discussed. Is this of any value? Can the source of the thump triangulated with this info?
Edit: just found it few posts back. Searched for seismic and found nothing. Should have searched for Thompson.
Mods: feel free to remove this post
Here are the positions for Glenn Thompson's sensors:
https://www.google.com/maps/d/viewer?mid=17Tim56aFrQKtcF2KStP05hG9A3M
The one that recorded the blip before the main event is located NNW of the pad between SLC 40 and 41.
-C
Edit: The data that I'm really interested in is the "pop" on the top channel at 13:07:11.
Trying to register for this site. Craig, my seismic&infrasound station is 0.87 miles NNE of SLC-40 (you said NNW).
Trying to register for this site. Craig, my seismic&infrasound station is 0.87 miles NNE of SLC-40 (you said NNW).(http://uploads.tapatalk-cdn.com/20160911/69fad97ab9681f6943e99f7bff5faa8a.jpg)
Not sure if I missed this being mentioned or discussed. Is this of any value? Can the source of the thump triangulated with this info?
Edit: just found it few posts back. Searched for seismic and found nothing. Should have searched for Thompson.
Mods: feel free to remove this post
Here are the positions for Glenn Thompson's sensors:
https://www.google.com/maps/d/viewer?mid=17Tim56aFrQKtcF2KStP05hG9A3M
The one that recorded the blip before the main event is located NNW of the pad between SLC 40 and 41.
-C
Edit: The data that I'm really interested in is the "pop" on the top channel at 13:07:11.
Thanks! Been reading for a long time, finally registered.Welcome to the forum! :)Long time listener, first time caller. I have read all 2100+ messages so far in this board and I haven't heard this exact theory I'm about to put forth.
I call this the "slow slump" theory. Since the static fire is the first time the full stack was fully integrated and was being fueled, I propose that there was not necessarily a manufacturing flaw but a borderline tolerance flaw, along with a borderline tolerance mating of the strongback to the stack. As the RP1 was being loaded the rocket would be creaking and would be triggering sensors within the rocket, but the difference would be there would be an accumulation of borderline tolerance flaws that would cause the rocket to slowly "slump" along the side of the rocket facing the strongback and would have lead to a minor leak of the rocket near the top of RP1 stage 2 tank only when the tank was full (around the time of the anomaly occurred). This leak was minor enough it would not have been observed easily on camera, but the RP1 was being atomized by LOX venting from S1 and carried up to be ignited by the oxygen rich venting on S2 until there was enough fuel to be ignited.
Sensor readings long before the anomaly would look different than prior static firings of the F9. The cause of the anomaly was a long running event while everyone is looking for a fast cascade of sensor reading, but culminated in the footage we have all seen in the video. The weak part of this theory is the ignition of this FAE event, but I'm postulating that given enough RP1, and oxidizer in this environment that any rust point on the strongback could have triggered the FAE, and subsequent LOV.
I'm just a curious armchair rocket sturgeon looking for answers like everyone else.
I'm thinking this is the way to look. It looks like a fuel air explosion. For that volume to develop, it seems like it would take some time. And the way the wind is blowing, seems likely at least one part, fuel or O2 would come from the GSE and blow towards the vehicle. Perhaps fuel was sprayed out and began mixing with O2 by the rocket. Then a spark near the rocket/GSE interface occurred causing the accident.
Need to look in detail at the video a ways before the accident to see if anything different can be seen, especially around the GSE.
Did USLR ever provide the exact coordinates for their camera? We now know that Glenn's sensor picked up the thump at 28.574183, -80.5724. If we know exactly where the USLR camera was, then we can see if the slight difference in arrival time for the thump intersects at the pad.
HiI believe that may be the rubber bumper on the cradle being obscured on and off again by the gaseous oxygen... Anyone else?
on the 70 frames slowdown link i notice what looks like a hole appear 3 or 4 seconds before the boom, does anyone else see this?
http://(https://s17.postimg.org/5n0e51sx7/spacex.jpg) (https://postimg.org/image/5n0e51sx7/)
Modified - no its not 3/4 seconds of course i'm slowing things down at lot, its very shortly before
and i also see a change in the 'fog' and things around it after this hole appears
yes, its unclear but the question is, is something happening here, or not..
Martin
[
.....
The other potential issue is items not being synchronized due to delays between when a channel is sampled and when it's sent. While Ethernet cannot supply a pure set of data values exactly when they happen (as a 3000 pin plug could) but the greater data rate would if necessary allow every channel to be time tagged.
In reality I suspect quite a few of those channels are events, essentially a time tag and a channel ID as and when necessary. A 4 byte entry can hold up to 4096 channel ID's and still time tag an even to the nearest 100 miliseconds in a 24 hour period. While I could believe some events might need recording down to a millisecond to find out if some events have happened together (giving 17 minutes of range with 20 bits of time stamp, or over 49 hours with a 32 bit time stamp to the nearest millisecond.
A substance that is a contact explosive with many organics at atmospheric pressures clearly is irrelevant to an investigation of an explosion.
A substance that is a contact explosive with many organics at atmospheric pressures clearly is irrelevant to an investigation of an explosion.
correct. Because there was no contact and no organics.
There is no case for air liquefying on the outside of the vehicle.
Again: boldfaced assertion doesn't make it true. You have a 23°C temperature differential. Your proposed "insulation" is 2,2W/m-K thermal conductivity. You're proposing an amount equal to seven thousandths of a millimeter of foam insulation, and claiming that it's enough to prevent a 23°C temperature differential. Good to know that I can insulate my house with a practically invisibly small amount of insulation.
I'll reiterate: if you want to be dismissive, give an actual reason behind your argument. Right now, your entire argument is built around, "because I say so".
I never said anything about proposed "insulation".
HiI believe that may be the rubber bumper on the cradle being obscured on and off again by the gaseous oxygen... Anyone else?
on the 70 frames slowdown link i notice what looks like a hole appear 3 or 4 seconds before the boom, does anyone else see this?
http://(https://s17.postimg.org/5n0e51sx7/spacex.jpg) (https://postimg.org/image/5n0e51sx7/)
Modified - no its not 3/4 seconds of course i'm slowing things down at lot, its very shortly before
and i also see a change in the 'fog' and things around it after this hole appears
yes, its unclear but the question is, is something happening here, or not..
Martin
Then do explain what is to prevent the formation of LOX on the outside of the tank, given that the inside is significantly colder than the boiling point of oxygen.
i'm definately seeing something happen in the cloud/fog on the slowed down video
let me describe the events, first a 'hole' appears, which i'm not saying is a hole but that's what i'll refer to it as. it could be a hole blown in the cloud, a real hole, an artifact
you will easily see this on the slowed down vid by stepping through the youtube by hitting pause/play quickly and slowing down to 0.25 speed
next, there is the 'disruption', which happens very quickly, but not simultaneously with the appearance of the hole
its very quick and happens literally from one frame to the next, giving the appearance of a frame skip on the video
this would require an extremely high pressure force as it changes the dynamic of the cloud and is marked by the appearance of 4 dark spots
i've screen grabbed the before/after on the disruption, but you will need to see it on the video to judge its validity as these stills don't bring out the noticability of the change...
(https://s18.postimg.org/uj0b5m4t1/spacex2.jpg) (https://postimg.org/image/uj0b5m4t1/)
I never said anything about proposed "insulation".
Then do explain what is to prevent the formation of LOX on the outside of the tank, given that the inside is significantly colder than the boiling point of oxygen.
No,Again: boldfaced assertion doesn't make it true. You have a 23°C temperature differential to account for (about a tenth of the difference between the inside and the outside). LOX.
No, you provide the work that shows LOX IS forming on the outside.
As a comment on external LOX - if there were such a layer, I'd expect it to be forming a vapor cloud where the LOX tank fill line was and not elsewhere. Having looked at closeup stills of the video for a too much time, I don't see anything like that.I never said anything about proposed "insulation".
Then do explain what is to prevent the formation of LOX on the outside of the tank, given that the inside is significantly colder than the boiling point of oxygen.
No,Again: boldfaced assertion doesn't make it true. You have a 23°C temperature differential to account for (about a tenth of the difference between the inside and the outside). LOX.
No, you provide the work that shows LOX IS forming on the outside.
1. It's colder than the boiling point of oxygen.
And that's the entire work right there. Either you think that there's some sort of insulation creating a significant temperature differential, or by the very definition of a boiling point, LOX will condense.
Don't give up looking, we can always use new eyes and resources!HiI believe that may be the rubber bumper on the cradle being obscured on and off again by the gaseous oxygen... Anyone else?
on the 70 frames slowdown link i notice what looks like a hole appear 3 or 4 seconds before the boom, does anyone else see this?
http://(https://s17.postimg.org/5n0e51sx7/spacex.jpg) (https://postimg.org/image/5n0e51sx7/)
Modified - no its not 3/4 seconds of course i'm slowing things down at lot, its very shortly before
and i also see a change in the 'fog' and things around it after this hole appears
yes, its unclear but the question is, is something happening here, or not..
Martin
I'm gonna have to agree with you there. I looked at the original video at 1/4th speed, frame by frame, for about twenty minutes and could not find a hole appearing. I do believe that is the cradle being inconsistently obscured and revealed by the vented gaseous oxygen.
He doesn't have to show his work because liquid air is not the issue.
Just move on.
Don't give up looking, we can always use new eyes and resources!HiI believe that may be the rubber bumper on the cradle being obscured on and off again by the gaseous oxygen... Anyone else?
on the 70 frames slowdown link i notice what looks like a hole appear 3 or 4 seconds before the boom, does anyone else see this?
http://(https://s17.postimg.org/5n0e51sx7/spacex.jpg) (https://postimg.org/image/5n0e51sx7/)
Modified - no its not 3/4 seconds of course i'm slowing things down at lot, its very shortly before
and i also see a change in the 'fog' and things around it after this hole appears
yes, its unclear but the question is, is something happening here, or not..
Martin
I'm gonna have to agree with you there. I looked at the original video at 1/4th speed, frame by frame, for about twenty minutes and could not find a hole appearing. I do believe that is the cradle being inconsistently obscured and revealed by the vented gaseous oxygen.
You know very well that the thermal inertia of aluminum is tiny.
If people are going to point to stuff in video frames, please, please say what the time code of the frame is. I'd suggest using either the first frame with the explosion in it as the start point, or the start of the video itself.
min:sec:frame
...When you say boundary layer, I interpret that to mean air-tank wall boundary. Therefore by the second law of thermodynamics, no LOX outside the tank.
Let's go with 70°K tank wall and 300°K external temp. 230K net temperature differential, boundary layer is 185°K, 115° boundary differential.
...
Ok, I've read through this thread over the last week or so and might have missed/forgotten some detail so forgive me. I was thinking as the RP-1 loading was complete by this point but previously under pressure to fill the tank. If there was some plumbing leak that sprayed/dripped RP-1 onto adjacent gear in the TEL, and that gear was warm, could it cause the RP-1 to slowly vaporize over time. This could happen until mixture was right and ignition source was found? Is there anything in the TEL that just gets warm to allow heating of the RP-1 in those 6 minutes? Seems like this is basic but don’t recall, please delete if duplicate.
Additionally, the initial deflagration looks quite wrong for an uncontrolled kerosene ignition. Too clean, too bright, no smoke/soot/partial burn anywhere.
Ice from airborne water vapor is normally pretty pure water. Pure enough that it would take an enormous amount of power to generate enough hydrogen to make the explosion.Additionally, the initial deflagration looks quite wrong for an uncontrolled kerosene ignition. Too clean, too bright, no smoke/soot/partial burn anywhere.
How about hydrogen? Hydrogen burns clean.
I'm fully willing to be told I'm nuts, but... it was a very humid day and frost would start building up quickly. What would happen if that frost managed to form an accidental short-circuit between some points (undefined for purposes of this question)? Could electrolysis break some of that frost into hydrogen and oxygen? And if that happened, could that rapidly building and layering frost start having a bunch of entrained hydrogen and oxygen bubbles, trapping much of it near its origin? And those bubbles might start to combine as gases form and expand within the ice layers.
My last physics class was a long time ago, so it's strongly possible I've made a basic mistake here. Just curious. I have no opinion on the ignition source, just trying to figure out the fuel.
Additionally, the initial deflagration looks quite wrong for an uncontrolled kerosene ignition. Too clean, too bright, no smoke/soot/partial burn anywhere.
How about hydrogen? Hydrogen burns clean.
I'm fully willing to be told I'm nuts, but... it was a very humid day and frost would start building up quickly. What would happen if that frost managed to form an accidental circuit between some points (undefined for purposes of this question)? Could electrolysis break some of that frost into hydrogen and oxygen? And if that happened, could that rapidly building and layering frost start having a bunch of entrained hydrogen and oxygen bubbles, trapping much of it near its origin? And those bubbles might start to combine as gases form and expand within the ice layers.
My last physics class was a long time ago, so it's strongly possible I've made a basic mistake here. Just curious. I have no opinion on the ignition source, just trying to figure out the fuel.
I've watch this clip all day, and can't see where I'm going wrong...
Frame #1 is T0 (no flame) (00:01:11:721)
Something appears on the right side at frame #3, which is very early in the event. I tracked it out as far as I could and circled the object. Some frames required filtering, which could just lead to image compression effects, but the object appears to be in the correct positions.
It appears to be coming towards the camera, and slowing down. (based on illumination and apparent size)
The solid two dots are projected guesses where the object should have been in the first two frames to end up where it is in frame #3.
In frame #2, the fire is to bright to spot it.
In frame #1, it's in what I would consider to be an interesting location...
Edit: Added video with no overlay. Added Time
What would happen if that frost managed to form an accidental short-circuit between some points (undefined for purposes of this question)? Could electrolysis break some of that frost into hydrogen and oxygen? And if that happened, could that rapidly building and layering frost start having a bunch of entrained hydrogen and oxygen bubbles, trapping much of it near its origin? And those bubbles might start to combine as gases form and expand within the ice layers.
And even if it did somehow break apart into oxygen and hydrogen, the hydrogen would float up and away quite quickly. Ever seen how fast a helium balloon floats up and away? Hydrogen would float up and away even faster.Sure, if it were immediately free to do so, but that's why I was thinking about trapped bubbles. And yes, hydrogen will find its way out of just about any container eventually, but on a much longer timescale than we're looking at.
And even if it did somehow break apart into oxygen and hydrogen, the hydrogen would float up and away quite quickly. Ever seen how fast a helium balloon floats up and away? Hydrogen would float up and away even faster.Sure, if it were immediately free to do so, but that's why I was thinking about trapped bubbles. And yes, hydrogen will find its way out of just about any container eventually, but on a much longer timescale than we're looking at.
I'm not married to this theory, but perhaps I should frame it a different way before I put it to bed:
We're looking for a fuel consistent with the first external bang. Hydrogen would be one candidate, but it's not native to the rocket. How could hydrogen get there? You can accidentally make it with electricity (which is definitely available) and water (which will invite itself to the party as frost, even if it melts later). Presence of salt to facilitate electrolysis is highly plausible near the ocean. We're currently struggling to identify how a FAE event got set up without a trace on the video we have, and electrolysis would be one way to invisibly build up a stock of invisible fuel.
That leaves questions: How much hydrogen would it take to generate the first bang? Is there any way that much hydrogen could have been trapped near the rocket somehow? That's when I thought of ice. After that, how much energy would you have to pour into electrolysis to get that much hydrogen? How long before that was the rocket cold enough to form frost? I don't know the answers to those.
And even if it did somehow break apart into oxygen and hydrogen, the hydrogen would float up and away quite quickly. Ever seen how fast a helium balloon floats up and away? Hydrogen would float up and away even faster.Sure, if it were immediately free to do so, but that's why I was thinking about trapped bubbles. And yes, hydrogen will find its way out of just about any container eventually, but on a much longer timescale than we're looking at.
I'm not married to this theory, but perhaps I should frame it a different way before I put it to bed:
We're looking for a fuel consistent with the first external bang. Hydrogen would be one candidate, but it's not native to the rocket. How could hydrogen get there? You can accidentally make it with electricity (which is definitely available) and water (which will invite itself to the party as frost, even if it melts later). Presence of salt to facilitate electrolysis is highly plausible near the ocean. We're currently struggling to identify how a FAE event got set up without a trace on the video we have, and electrolysis would be one way to invisibly build up a stock of invisible fuel.
That leaves questions: How much hydrogen would it take to generate the first bang? Is there any way that much hydrogen could have been trapped near the rocket somehow? That's when I thought of ice. After that, how much energy would you have to pour into electrolysis to get that much hydrogen? How long before that was the rocket cold enough to form frost? I don't know the answers to those.
A substance that is a contact explosive with many organics at atmospheric pressures clearly is irrelevant to an investigation of an explosion.
correct. Because there was no contact and no organics.
There is no case for air liquefying on the outside of the vehicle.
Anyway, modelling this is hard (CFD), but the experiment "what happens when a rocket tank filled with LOX is exposed to air" has been performed and we have people like Jim here with first hand knowledge of the results - no LOX forms outside the tank.
This is the frame before the explosion and the explosion frame and the two combined.
Anyway, modelling this is hard (CFD), but the experiment "what happens when a rocket tank filled with LOX is exposed to air" has been performed and we have people like Jim here with first hand knowledge of the results - no LOX forms outside the tank.
Formation of liquid air has been reported at LN2 temperatures (https://www.freelists.org/post/arocket/Keeping-moisture-out-of-cryogenic-valves,7) (which subcooled LOX will certainly reach). Apparently this happens if an air-facing surface cools quickly enough that frost doesn't have enough time to form before it's washed away by liquid air. This may also be climate-dependent. I could see this happening at, say, a LOX valve, pipe, or inlet in some weather where it wouldn't in other conditions.
The snow will form first and prevent the air from liquefying.
I can't believe I just registered to post 'bird poop'. ???
Another imaging tidbit derived from something called Lucky Imaging.
HiI believe that may be the rubber bumper on the cradle being obscured on and off again by the gaseous oxygen... Anyone else?
on the 70 frames slowdown link i notice what looks like a hole appear 3 or 4 seconds before the boom, does anyone else see this?
http://(https://s17.postimg.org/5n0e51sx7/spacex.jpg) (https://postimg.org/image/5n0e51sx7/)
Modified - no its not 3/4 seconds of course i'm slowing things down at lot, its very shortly before
and i also see a change in the 'fog' and things around it after this hole appears
yes, its unclear but the question is, is something happening here, or not..
Martin
Another imaging tidbit derived from something called Lucky Imaging.
The area I've circled seems to be a bit brighter than the general background behind the rocket.
I'm wondering if cork insulation can be a fuel source if somehow it becomes saturated with LOX. Is the cork at all permeable to gaseous oxygen? Might the boundary between cork and aluminum tank be cold enough to support the formation of a thin layer of LOX? Then an ignition source, such as a spark, would have to somehow find that vulnerable patch.
On the other hand, I gather many vehicles use cork, so it must be possible to do so safely. Just a thought.
Edit: after searching this thread more carefully, this has already been asked, and one reply stated that there is no cork on the second stage. Perhaps the nearest source of carbon would be the composite interstage, then.
Edit 2: are any of the TEL S2 LOX lines insulated with cork?
Anyway, modelling this is hard (CFD), but the experiment "what happens when a rocket tank filled with LOX is exposed to air" has been performed and we have people like Jim here with first hand knowledge of the results - no LOX forms outside the tank.
Formation of liquid air has been reported at LN2 temperatures (https://www.freelists.org/post/arocket/Keeping-moisture-out-of-cryogenic-valves,7) (which subcooled LOX will certainly reach). Apparently this happens if an air-facing surface cools quickly enough that frost doesn't have enough time to form before it's washed away by liquid air. This may also be climate-dependent. I could see this happening at, say, a LOX valve, pipe, or inlet in some weather where it wouldn't in other conditions.
The reason why liquid-hydrogen tanks don't normally form a frost layer (and therefore need deliberately-provided insulation) is that the dripping liquid air usually washes the frost off before it can get established. Apparently you *can* get a frost layer on them if the initial conditions are just right. Maybe you're running into a milder version of the same thing, with the tank bottom sometimes getting too cold too fast and the frost layer not getting well started before the liquid air starts to show up.
The only observable candidate, in the observable area, for unmodelled complex behaviour is the lower pads of the pivoting cradle.
But fast fill means the sides are not in this state for long. I'd take a very close look at this if I was on the investigation board.
Perhaps the nearest source of carbon would be the composite interstage, then.
No such mechanism was in work. There is no play between the cradle and grabbers
Regarding LOX build-up vs "something else": in the first frame, a fragment is seen flying "to the right", which seems to be moving quite "fast". For me, the fragment seems expelled at the T=0 initial event. Would a LOX-fueled boom do that? At least the LOX must then have been confined in some box or thing that would 'blow up' or at least could create the power to expel parts.I would expect that the initial fragment blown away from the initial explosion is located around the pad area. It probably got enveloped and mostly destroyed by the resultant explosion, but a survey of the GSE around the upper stage for hardware missing might identify it (assuming it came from the GSE which I think it did).
Moreover, if indeed the fragment would be expelled at T=0, it would be worthwile finding it back. Also, while it is seen moving to the right, it could also be first reflected off the hull of the rocket. Or it could be there were more fragments, some moving "to the left", impacting the vehicle.
I would expect that the initial fragment blown away from the initial explosion is located around the pad area. It probably got enveloped and mostly destroyed by the resultant explosion, but a survey of the GSE around the upper stage for hardware missing might identify it (assuming it came from the GSE which I think it did).
Pad did not damage tank.
No turnbuckle snapped before the vehicle exploded.
Strong back did not collapse before the vehicle exploded
Morning cup of Joe thought... Those lower cradle bumpers against the sides of the stage have a pivot pin. Are they lubricated to stay free from binding? If they were lubricated and subject to a high pressure LOX vent blast, what would happen if the lube was inappropriate for a oxygen rich environment under pressure?
And nothing is happening there. There is no movement between the pads and the vehicle
I've just had a spooky thought. What if the "source of heat" was not local ... but 150 million km away, the Sun? Could the morning Sun reflect of various elements of the TEL and focus on a single spot? That bright area we see could be the Sun shining through a buildup of gaseous oxygen between the second stage and TEL. All we need now is a source of fuel, most likely from the TEL but perhaps also from the vehicle.
Agreed, we would need a fuel mist in the mix somehow...Morning cup of Joe thought... Those lower cradle bumpers against the sides of the stage have a pivot pin. Are they lubricated to stay free from binding? If they were lubricated and subject to a high pressure LOX vent blast, what would happen if the lube was inappropriate for a oxygen rich environment under pressure?
A fire but not a blast
Pad did not damage tank.
No turnbuckle snapped before the vehicle exploded.
Strong back did not fail before the vehicle exploded
The strong back is much, much more robust than the rocket. It is there to protect the vehicle and provide more stiffness to the vehicle. Vehicle movement is not going to damage the strong back. The strong back also lifts the vehicle and cantilevered payload vertical.
There are three things required: a fuel, an oxidizer, and an ignition source. It seems most of the folks posting theories are focusing on whichever of the three they like most and ignoring or wildly hand-waving about the rest.
Suppose there was lox-saturated frost on the rocket. Then what?
Suppose the a hole is poked in the tank. Then what?
Remember, all three have to occur either simultaneously or invisibly, since there was no prior indication before the explosion.
Further, (im)probabilities multiply. So if you postulate a highly unlikely source for one of the three, it seems your burden is much higher for showing that the other two are quite likely/common.
To take an example, suppose that there is lox-saturated frost on the vehicle (unlikely, as direct observation of prior rockets hasn't evidenced it, but let's take this as the given). If you want to say that the fuel source is the paint or the aluminum skin, it seems you should have the burden of showing that LOX-related incidents with painted rockets or aluminum tanks are likely and common. But in fact LOX is carried in painted aluminum tanker trucks without incident every day. And then you *also* have to show that there was a not-unlikely ignition source---and a powerful one, given that paint and aluminum are not exactly easy to ignite, and aluminum doesn't spark when it is mechanically deformed. I don't think anyone has offered a plausible scenario there.
Let's try to make sure that all requirements of the explosion are addressed; that may trim down the number of wild theories.
Jim,
Does the Vehicle shrink at all vertically when it cools? If it does, will the strongback and that support point move lower with it, or is it designed to slide?
I think the gusty winds blowing on the higher and wider payload could have caused the pivot cradle to do some things that even modelling a higher constant wind velocity might have missed, such as a resonance. And I could imagine the strongback creating some vortices where stagnant air could dry out due to declining temperature.
It almost doesn't matter. It seems to be turning into another Columbia incident where the unthinkable and supposedly impossible happens. I think all of us are hoping that something will nudge one of you knowledgeable guys to think "This can't possibly be the cause UNLESS some seemingly impossible event occurs - like liquid Oxygen dripping down the rocket" and then eventually finding that maybe, just maybe it COULD happen say one in 1000 times instead of never.
Jim,
Does the Vehicle shrink at all vertically when it cools? If it does, will the strongback and that support point move lower with it, or is it designed to slide?
I think the gusty winds blowing on the higher and wider payload could have caused the pivot cradle to do some things that even modelling a higher constant wind velocity might have missed, such as a resonance. And I could imagine the strongback creating some vortices where stagnant air could dry out due to declining temperature.
It almost doesn't matter. It seems to be turning into another Columbia incident where the unthinkable and supposedly impossible happens. I think all of us are hoping that something will nudge one of you knowledgeable guys to think "This can't possibly be the cause UNLESS some seemingly impossible event occurs - like liquid Oxygen dripping down the rocket" and then eventually finding that maybe, just maybe it COULD happen say one in 1000 times instead of never.
Anything related to a mechanic failure would first show a breach in the vehicle followed by massive venting before the explosion. See CRS
The problem, I feel, is ignition source. There's no electrical events and no heat sources in that area, by design.
The mechanism I propose is that a small leak developed in the LOX line running down through the RP1 tank. Initially a slug of LOX went into the RP1 tank due to it's density and immediately evaporated in the RP1 causing a slight increase in pressure that drove RP1 into the pipe. The increase in pressure in the RP1 tank could be very small, just enough to overcome a few meters of LOX head in the filling tank, so it may not be obvious in the pressure readings in the RP1 tank. RP1, liquid and solid, would float in LOX.
All vehicle can flex and do flex in flight and on the pad.
What if it was a mechanical failure on the strongback which generated fast debris ("flying metal bolt") puncturing RP-1 tank or piping?I believe that its been mentioned...
This explains everything. The "twang" sound, the RP-1 mist, the ignition source.
And would, I imagine, leave an unmistakable trace in the telemetry data, like bangs, groans and readings way outside the norm.
hello,
"Негромкий инсульт" частной космонавтики
Quote from: Strangerhello,
"Негромкий инсульт" частной космонавтики
(don't shoot the translator, please transfer to "wacky" thread if this doesn't make sense)
Hypothesis in this (now deleted) post was approximately:
- SpaceX subcooled oxygen to increase mass by 15% (density 1140 kg/m3 goes up to 1300 kg/m3),
- transport of LOX requires certain maximum speed (? 2m/s ~= 7km/h) to avoid problems,
- to load larger mass of subcooled oxygen in required time, transfer speed might have been increased,
- due to LOX flow characteristics, a hydroshock could have happened in LOX supply line,
- if line is estimated at 100m length, 10cm diameter, it could have carried about 1t of LOX at about 3m/s ~= 11km/h,
- hydroshock would have converted this to energy (and heat?) rupturing LOX supply line, possibly also RP-1 supply line,
- "quiet bang" could have been sound of hydroshock.
If such hypothesis is true, oxygen plumbing would need to be redesigned for subcooled LOX.
There was more information and details in the original post, I could have also wrongly translated/understood something critical for the described idea.
It may have been a transient pressure increase if the leak was sealed by RP1 freezing at the break after some got into the line and then the stream of RP1 froze as the tank pressure decreased.
The back and forth movement of fluid is not going to happen. The pressure in the fuel tank is not going to overcome the pressure in the LOX line.
An increase of pressure to overcome a few meters of LOX head is going to be a few psi. That is noticeable
The problem, I feel, is ignition source. There's no electrical events and no heat sources in that area, by design.
I disagree. The problem is the fuel, not ignition source.
Possible ignition sources: electrical wiring. Moving metal parts. Strongback has both.
Of course, SpaceX tries to reduce the possibilities for ignition sources there (as in: electrical insulation should be not damaged), but mainly it depends on not having PR-1 or something else combustible dripping there!
My main concern would be if it were made of Aluminum, it could have melted in the fire.I would expect that the initial fragment blown away from the initial explosion is located around the pad area. It probably got enveloped and mostly destroyed by the resultant explosion, but a survey of the GSE around the upper stage for hardware missing might identify it (assuming it came from the GSE which I think it did).
Mangled, roughed up, bent, torn, exposed to extreme heat, yes. But if landed outside of the raging RP-1 fire, it would not have been "destroyed". Beyond what have been consumed/melted in the fire that raged after the explosions the entire rocket still exists in smaller smaller pieces spread across a large area. SpaceX still has a Falcon 9, some assembly required ;)
When you blast in a quarry the rock does not disappear, it just gets shattered and shifted around. You still need a front end loader to scoop it up and move it out of the quarry.
All vehicle can flex and do flex in flight and on the pad.
But you have completely discounted any strongback, contact points or mechanical failures. No visible external plumes to ignite.
So, bird picked at eletrical insulation for it's nest,
The back and forth movement of fluid is not going to happen. The pressure in the fuel tank is not going to overcome the pressure in the LOX line.OK, another variant is that the leak was already in the LOX pipe running through the RP1 tank before the LOX loading was started. The RP1 was very slowly leaking into the pipe, then the LOX started loading and filling the pipe. That froze the RP1 at the leak, sealing the leak and preventing the RP1 tank pressure rise.
An increase of pressure to overcome a few meters of LOX head is going to be a few psi. That is noticeable
In the nominal operation, there absolutely must be no fuel on or near the rocket or TEL, nothing at all which can combust not only in ordinary air, but also in oxygen-enriched LOX boiloff plumes.
If there was fuel, _that_ is the problem. Not the ignition source.
It's impractical to eliminate all sources of ignition for such a situation, and SpaceX shouldn't try to debug that. They should figure out where did that fuel came from. Not how it ignited.
The problem, I feel, is ignition source. There's no electrical events and no heat sources in that area, by design.
I disagree. The problem is the fuel, not ignition source.
Possible ignition sources: electrical wiring. Moving metal parts. Strongback has both.
Of course, SpaceX tries to reduce the possibilities for ignition sources there (as in: electrical insulation should be not damaged), but mainly it depends on not having PR-1 or something else combustible dripping there!
Given that we're looking for "swiss cheese" failure modes, where individual minor failures are not problematic, both have to be the problem, I suppose.
But you have completely discounted any strongback, contact points or mechanical failures. No visible external plumes to ignite.
Those would be seen in the video
The off-nominal presence of RP-1 leak would be enough. It could be happening for minutes without visible effects (on video and in telemetry), waiting for a normally completely insignificant and harmless event, such as metal parts rubbing, setting it off.
A cracked through beam would not show up until it was needed. This is one upright out of 4. The rest are not particularly elastic.
In the video, the fluid does not ignite because he is careful to have it in a container with the fluid level well below the opening. Liquid propane burns the same way. a steel container can be lit and the flame will hover over the opening until the fuel is exhausted. Just don't tip it over or break the container. Him doing that in a glass jar is very dangerous. If the heat broke the jar ? ? he would have to run like hell to escape it !
The off-nominal presence of RP-1 leak would be enough. It could be happening for minutes without visible effects (on video and in telemetry), waiting for a normally completely insignificant and harmless event, such as metal parts rubbing, setting it off.
RP-1 is not like gasoline. A torch doesn't even light it
https://www.youtube.com/watch?v=7nL10C7FSbE
I believe SpaceX shines a laser some place on the 2nd stage to measure sway. Therefore they would have known if the rocket was moving out of a well defined tolerance.
Which is why I also posited an RP1 tank over-pressure approximately 1 standard deviation above the mean- not so rare to be remarked on, but enough that, with an undetected tank defect, would be enough to aerosolize a leak.
The off-nominal presence of RP-1 leak would be enough. It could be happening for minutes without visible effects (on video and in telemetry), waiting for a normally completely insignificant and harmless event, such as metal parts rubbing, setting it off.
RP-1 is not like gasoline. A torch doesn't even light it
Which is why I also posited an RP1 tank over-pressure approximately 1 standard deviation above the mean- not so rare to be remarked on, but enough that, with an undetected tank defect, would be enough to aerosolize a leak.
The off-nominal presence of RP-1 leak would be enough. It could be happening for minutes without visible effects (on video and in telemetry), waiting for a normally completely insignificant and harmless event, such as metal parts rubbing, setting it off.
RP-1 is not like gasoline. A torch doesn't even light it
A cracked through beam would not show up until it was needed. This is one upright out of 4. The rest are not particularly elastic.
The fracture/collapse and subsequent rupture would be seen in the video before the explosion.
Doesn't the partial pressure of GOX reduce it's condensation point considerably? The partial pressure of O2 in normal atmosphere is 21 kPa, which if I'm reading the phase diagram right reduces the vapor temperature by almost half of the temperature differential between subcooled and boiling LOX.This is a very relevant point. Thank you envy887!
It's like a glass of water at room temperature: despite the fact that the outside of the glass is MUCH cooler than the boiling point of water, water vapor in the atmosphere does not condense because the partial pressure of water in a normal atmosphere is only a few kPa. The dew point of water varies with partial pressure, the condensation point of O2 should as well.
The aluminum-lithium skin might be insulation enough to prevent LOX formation even without ice buildup, as long as the sounding atmosphere is mostly nitrogen (i.e. the vented GOX doesn't comprise the majority of the local atmosphere for a long duration).
I don't believe your story on either the fuel or the ignition source, even if I grant your lox-frost theory for purposes of discussion.
After all, there is plenty of GOX around as well. Why hasn't the paint burst into flames before?
That's a LOX-soaked *hydrocarbon*. You're postulating LOX-soaked paint being a similar contact explosive... And even then you're missing the "heavy fire truck" part of the anecdote. (Also it fails on account of explosive mass: 6" of asphalt vs a millimeter of paint).I don't believe your story on either the fuel or the ignition source, even if I grant your lox-frost theory for purposes of discussion.
After all, there is plenty of GOX around as well. Why hasn't the paint burst into flames before?
Well, I was thinking of upthread stories like the LOX-soaked tarmac that exploded when a fire-truck drove over it. That had never burst into flames before either, despite lots of GOX and hot sun. I have to rely on people with more practical experience of LOX ignition than I have ...
That's a LOX-soaked *hydrocarbon*. You're postulating LOX-soaked paint being a similar contact explosive... And even then you're missing the "heavy fire truck" part of the anecdote. (Also it fails on account of explosive mass: 6" of asphalt vs a millimeter of paint).I don't believe your story on either the fuel or the ignition source, even if I grant your lox-frost theory for purposes of discussion.
After all, there is plenty of GOX around as well. Why hasn't the paint burst into flames before?
Well, I was thinking of upthread stories like the LOX-soaked tarmac that exploded when a fire-truck drove over it. That had never burst into flames before either, despite lots of GOX and hot sun. I have to rely on people with more practical experience of LOX ignition than I have ...
That's a LOX-soaked *hydrocarbon*. You're postulating LOX-soaked paint being a similar contact explosive... And even then you're missing the "heavy fire truck" part of the anecdote. (Also it fails on account of explosive mass: 6" of asphalt vs a millimeter of paint).Agreed. That's the genesis of my conjecture involving a frozen slush-like RP1/LOX chunk being propelled by the LOX boiling striking the edge of the vent being the ignition source.
But on a humid day, with a tropical storm moving in, maybe the frost layer grew unusually thick and fluffy?
The rupture WAS visible as a huge fireball.
No, there would be fluid release before the flame. See CRS-7
Search bleve.
Tanks were not at flight pressure, but if the tank was slightly overfilled, there would be some purely internally generated pressure as subcooled Rp1 warmed up. Tanks would of course be designed to withstand this, for days on end, or it would be considered a fault. It would show up on the sensors, but be within tolerance. Because Acceptable Tolerance is a thing.Which is why I also posited an RP1 tank over-pressure approximately 1 standard deviation above the mean- not so rare to be remarked on, but enough that, with an undetected tank defect, would be enough to aerosolize a leak.
The off-nominal presence of RP-1 leak would be enough. It could be happening for minutes without visible effects (on video and in telemetry), waiting for a normally completely insignificant and harmless event, such as metal parts rubbing, setting it off.
RP-1 is not like gasoline. A torch doesn't even light it
First, per the many-times-posted F9 FT countdown flow, tanks were not at flight pressure. Second, do you know what the mean pressure of the RP1 tank would be? Third, do you know how well-controlled and repeatably pressure is maintained so that you can determine how large or small a single standard deviation is? Fourth, just how inaccurate and/or imprecise (*) do you think SpaceX's pressure transducers would have to be for them not to notice such deviance? Fifth, do you know enough about the S2 umbilicals to know if and where there might be check valves, cut-off valves and/or drains? Sixth, with tanks not yet at flight pressure, are you confident that SpaceX keeps GSE pressurized with RP1 to allow fuel to aerosolize though a leak? And even if so, I refer you back up to Nos. 2, 3 and 4 above.
(*) There is a difference between accuracy and precision. I'm just going to go ahead and assume (I know, I know ...) that anyone here who posits this kind of theory understands this difference.
The heat finally melts the tank wall. In an aluminium alloy thin wall tank this is alarmingly quick. Look up the regulator fires on thick wall components. They were instant and had no fuel except the aluminium.
I'm wondering if cork insulation can be a fuel source if somehow it becomes saturated with LOX. Is the cork at all permeable to gaseous oxygen? Might the boundary between cork and aluminum tank be cold enough to support the formation of a thin layer of LOX? Then an ignition source, such as a spark, would have to somehow find that vulnerable patch.
On the other hand, I gather many vehicles use cork, so it must be possible to do so safely. Just a thought.
Edit: after searching this thread more carefully, this has already been asked, and one reply stated that there is no cork on the second stage. Perhaps the nearest source of carbon would be the composite interstage, then.
Edit 2: are any of the TEL S2 LOX lines insulated with cork?
No cork on stage 2
The rupture WAS visible as a huge fireball.
No, there would be fluid release before the flame. See CRS-7
Search bleve. The fuel never gets out of the tank first. The heat finally melts the tank wall. In an aluminium alloy thin wall tank this is alarmingly quick. Look up the regulator fires on thick wall components. They were instant and had no fuel except the aluminium.
Once this initial event occurs the rest of the destruction is guaranteed.
Tanks were not at flight pressure, but if the tank was slightly overfilled, there would be some purely internally generated pressure as subcooled Rp1 warmed up. Tanks would of course be designed to withstand this, for days on end, or it would be considered a fault. It would show up on the sensors, but be within tolerance. Because Acceptable Tolerance is a thing.
What would that pressure be? I do not know. What IS the expansion of subcooled RP1? Wound it be enough that a pinhole tank leak could cause aerosolization? That is my unproven assertion.
Any cork on the TEL in the vicinity of S2? Are the TEL LOX lines insulated, and if so, with what?
Of course you're right that I have very little, or no, evidence for the paint as fuel, especially since I don't even know what kind of paint it is (can anyone here tell us that?) That's why I wrote " ... the paint? the tank Al?" so hesitantly.That's a LOX-soaked *hydrocarbon*. You're postulating LOX-soaked paint being a similar contact explosive... And even then you're missing the "heavy fire truck" part of the anecdote. (Also it fails on account of explosive mass: 6" of asphalt vs a millimeter of paint).I don't believe your story on either the fuel or the ignition source, even if I grant your lox-frost theory for purposes of discussion.
After all, there is plenty of GOX around as well. Why hasn't the paint burst into flames before?
Well, I was thinking of upthread stories like the LOX-soaked tarmac that exploded when a fire-truck drove over it. That had never burst into flames before either, despite lots of GOX and hot sun. I have to rely on people with more practical experience of LOX ignition than I have ...
There would however be head pressure if a postulated leak was low down on the tank.Tanks were not at flight pressure, but if the tank was slightly overfilled, there would be some purely internally generated pressure as subcooled Rp1 warmed up. Tanks would of course be designed to withstand this, for days on end, or it would be considered a fault. It would show up on the sensors, but be within tolerance. Because Acceptable Tolerance is a thing.
What would that pressure be? I do not know. What IS the expansion of subcooled RP1? Wound it be enough that a pinhole tank leak could cause aerosolization? That is my unproven assertion.
No, the tank is not closed. It is still vented
There would however be head pressure if a postulated leak was low down on the tank.Tanks were not at flight pressure, but if the tank was slightly overfilled, there would be some purely internally generated pressure as subcooled Rp1 warmed up. Tanks would of course be designed to withstand this, for days on end, or it would be considered a fault. It would show up on the sensors, but be within tolerance. Because Acceptable Tolerance is a thing.
What would that pressure be? I do not know. What IS the expansion of subcooled RP1? Wound it be enough that a pinhole tank leak could cause aerosolization? That is my unproven assertion.
No, the tank is not closed. It is still vented
This is a frame of the CRS-7 failure just before the explosion showing some kind of precursor damage.
Not one large enough to form a propellant mist, and that doesn't square with where the event took place.How about a stream of high velocity GOX formed by LOX boiling in the LOX pipe atomizing RP1 pulled into it by Bernoulli through a crack in the LOX pipe?
But on a humid day, with a tropical storm moving in, maybe the frost layer grew unusually thick and fluffy?
It was a standard Florida day. The storm had no bearing on the weather. It was no more humid or dryer, no more hotter or cooler, no more stiller or winder than a typical Florida day in the summer.
There is no fluffy frost or LOX on the side of the vehicle. Look at previous launches
And again, if there was LOX it would evaporate upon running down the tank when it hits RP-1 temps
The pressure differential in the LOX feedline would be in the wrong direction for that to happen. If there were to be a leak, it would be into the RP-1 tank, not into the LOX feedline.Not one large enough to form a propellant mist, and that doesn't square with where the event took place.How about a stream of high velocity GOX formed by LOX boiling in the LOX pipe atomizing RP1 pulled into it by Bernoulli through a crack in the LOX pipe?
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1582381#msg1582381 (http://forum.nasaspaceflight.com/index.php?topic=30981.msg1582381#msg1582381)
The pressure differential in the LOX feedline would be in the wrong direction for that to happen. If there were to be a leak, it would be into the RP-1 tank, not into the LOX feedline.I'm proposing that the leak started before the LOX was loaded and as the LOX started filling the feed line it was boiling and sending a stream of high velocity GOX up the line that pulled the RP1 into it and atomized it in addition to the RP1 that had already leaked into the pipe.
Thinking about structural failure - not a burning event that started this but a stage structural failure that led to propellant rupture and ignition.
The stage was test fired in McGregor at some point in its life, meaning it was loaded, pressurized and unloaded without failing.
...
A bit of pedantry, but I don't believe it's possible to static fire a Merlin 1D Vac.
The upper stage is, iirc, fuelled at McGregor, but not fired.
I'm proposing that the leak started before the LOX was loaded and as the LOX started filling the feed line it was boiling and sending a stream of high velocity GOX up the line that pulled the RP1 into it and atomized it in addition to the RP1 that had already leaked into the pipe.
No. It needs too many miracles to happen in succession.Not an especially strong argument.
No. It needs too many miracles to happen in succession.Not an especially strong argument.
The only fault I'm suggesting is a leak into the LOX line. After that, the stage has a situation of heavily hydrocarbon contaminated LOX which is an explosion waiting to happen.
There are three things required: a fuel, an oxidizer, and an ignition source. It seems most of the folks posting theories are focusing on whichever of the three they like most and ignoring or wildly hand-waving about the rest.
Suppose there was lox-saturated frost on the rocket. Then what?
Suppose the a hole is poked in the tank. Then what?
Remember, all three have to occur either simultaneously or invisibly, since there was no prior indication before the explosion.
Further, (im)probabilities multiply. So if you postulate a highly unlikely source for one of the three, it seems your burden is much higher for showing that the other two are quite likely/common.
I feel there are a few plausable minor explanations for fuel- the strongback hydraulics, the RP1 tank, the stage 2 gimbal hydrolics- that only need a few coincidences to happen.
Oxidiser is dead simple. Lox-Frost shouldnt even be nessisary for the fuel sources I feel are most likely. If a leak is under sufficent pressure to aerosolize the fuel, a FAE can develop with normal air.
The problem, I feel, is ignition source. There's no electrical events and no heat sources in that area, by design. Someone suggesed a one-in-a-million solar mirror ignition- while unlikely, it should be relatively simple (though not easy) to retroactively prove or disprove, as we've got a bazilion pictures of the erector.
I find that theory unlikely, but what ignition sources -are- plausable?
A bit of pedantry, but I don't believe it's possible to static fire a Merlin 1D Vac.
The upper stage is, iirc, fuelled at McGregor, but not fired.
https://www.youtube.com/watch?v=O90FROx8J3Y
Because there was no ignition source. You can mix LOX and hydrocarbon fuel and it won't go off spontaneously, it needs an ignition source or a shock. I'm suggesting that some of the frozen RP1 particles stuck together in the LOX tank to form a pellet of frozen RP1 and LOX with enough mass that when it was thrown by the boiling action at the top of the LOX tank it hit with enough energy to shock ignite itself.No. It needs too many miracles to happen in succession.Not an especially strong argument.
The only fault I'm suggesting is a leak into the LOX line. After that, the stage has a situation of heavily hydrocarbon contaminated LOX which is an explosion waiting to happen.
Why wouldn't the LOX have reacted violently to the hydrocarbon contamination immediately at the start of LOX load?
You mean, that the stage then vented a fuel-gox mix, ready to explode?No. It needs too many miracles to happen in succession.Not an especially strong argument.
The only fault I'm suggesting is a leak into the LOX line. After that, the stage has a situation of heavily hydrocarbon contaminated LOX which is an explosion waiting to happen.
https://en.wikipedia.org/wiki/Oxyliquit (https://en.wikipedia.org/wiki/Oxyliquit)
Essentially. My conjecture is that the frozen RP1, either through mechanical agitation in the boiling LOX or because it was atomized by Bernoulli in the LOX pipe, was blown out the vent as a cloud of fine particles, some of which had LOX either incorporated internally or wetting the surface.You mean, that the stage then vented a fuel-gox mix, ready to explode?No. It needs too many miracles to happen in succession.Not an especially strong argument.
The only fault I'm suggesting is a leak into the LOX line. After that, the stage has a situation of heavily hydrocarbon contaminated LOX which is an explosion waiting to happen.
Because there was no ignition source. You can mix LOX and hydrocarbon fuel and it won't go off spontaneously, it needs an ignition source or a shock. I'm suggesting that some of the frozen RP1 particles stuck together in the LOX tank to form a pellet of frozen RP1 and LOX with enough mass that when it was thrown by the boiling action at the top of the LOX tank it hit with enough energy to shock ignite itself.No. It needs too many miracles to happen in succession.Not an especially strong argument.
The only fault I'm suggesting is a leak into the LOX line. After that, the stage has a situation of heavily hydrocarbon contaminated LOX which is an explosion waiting to happen.
Why wouldn't the LOX have reacted violently to the hydrocarbon contamination immediately at the start of LOX load?
Ah, but it is. There are a wide variety of such explosives using a lot of different types of fuel. Things like carbon black and charcoal I believe are used because they are less sensitive to detonation. Fuels that are more flammable are more dangerous and some will self detonate.
https://en.wikipedia.org/wiki/Oxyliquit (https://en.wikipedia.org/wiki/Oxyliquit)
Not applicable to RP-1
Those are the rest of the miracles. I can tell you that it didn't happen that wayHere are the steps:
The understanding I had (which various people mention in this thread) is that the extended nozzle means the stage can not be tested.
What happens to RP-1 in densified LOX? Does it freeze, dissolve, float, sink?Those are the rest of the miracles. I can tell you that it didn't happen that wayHere are the steps:
1) Leak into the LOX line - improbable, but something improbable demonstrably happened.
2) LOX boiling in the line picking up the leaked RP1 and sucking in more. For a relatively small leak such as a crack, why wouldn't this be expected to happen?
3) LOX freezes the RP1 in the leak before the LOX pressure builds up enough to flow into the RP1 tank. How would this not happen? RP1 gets very viscous as it cools and freezes.
4) Frozen RP1 breaks up into fine particles. This I have no proof of and absent a cryogenic explosives lab have no way to test, but it doesn't seem impossible.
5) Cloud of particles goes out vent. If the particles were fine, why wouldn't they?
6) A clump of frozen RP1 mixed with LOX strikes a surface and ignites. The LOX comes from the LOX tank it's in, the explosion is expected and is one of the reasons people worry about not contaminating LOX.
What happens to RP-1 in densified LOX? Does it freeze, dissolve, float, sink?
Consensus seems to be, that the initial fireball was a fuel-air explosion. If RP-1 leaked into the LOX tank and then vented with the GOX, all ingredients would be in place. It just needs a tiny spark for ignition.
Can you explain the missing beams, broken off, as opposed to heated and distorted by a fireball? Why would a strut in compression by a simple 10 tonne weight break off. Why was one grabber only distorted? If it was all destroyed by the blast why was the blast selective between neighbouring struts and beams?
What happens to RP-1 in densified LOX? Does it freeze, dissolve, float, sink?Those are the rest of the miracles. I can tell you that it didn't happen that wayHere are the steps:
1) Leak into the LOX line - improbable, but something improbable demonstrably happened.
2) LOX boiling in the line picking up the leaked RP1 and sucking in more. For a relatively small leak such as a crack, why wouldn't this be expected to happen?
3) LOX freezes the RP1 in the leak before the LOX pressure builds up enough to flow into the RP1 tank. How would this not happen? RP1 gets very viscous as it cools and freezes.
4) Frozen RP1 breaks up into fine particles. This I have no proof of and absent a cryogenic explosives lab have no way to test, but it doesn't seem impossible.
5) Cloud of particles goes out vent. If the particles were fine, why wouldn't they?
6) A clump of frozen RP1 mixed with LOX strikes a surface and ignites. The LOX comes from the LOX tank it's in, the explosion is expected and is one of the reasons people worry about not contaminating LOX.
Consensus seems to be, that the initial fireball was a fuel-air explosion. If RP-1 leaked into the LOX tank and then vented with the GOX, all ingredients would be in place. It just needs a tiny spark for ignition.
Here are the steps:
1) Leak into the LOX line.
Here are the steps:
1) Leak into the LOX line.
Going to stop you right there. How does something leak into a pressurised line?
And the other way around? LOX leaking into the RP-1 tank? The LOX would boil away and vent into the environment. Could it take enough fuel with it for the initial fuel-air explosion? The external walls would not be affected, it just needs the existing vents to escape.What happens to RP-1 in densified LOX? Does it freeze, dissolve, float, sink?Those are the rest of the miracles. I can tell you that it didn't happen that wayHere are the steps:
1) Leak into the LOX line - improbable, but something improbable demonstrably happened.
2) LOX boiling in the line picking up the leaked RP1 and sucking in more. For a relatively small leak such as a crack, why wouldn't this be expected to happen?
3) LOX freezes the RP1 in the leak before the LOX pressure builds up enough to flow into the RP1 tank. How would this not happen? RP1 gets very viscous as it cools and freezes.
4) Frozen RP1 breaks up into fine particles. This I have no proof of and absent a cryogenic explosives lab have no way to test, but it doesn't seem impossible.
5) Cloud of particles goes out vent. If the particles were fine, why wouldn't they?
6) A clump of frozen RP1 mixed with LOX strikes a surface and ignites. The LOX comes from the LOX tank it's in, the explosion is expected and is one of the reasons people worry about not contaminating LOX.
Consensus seems to be, that the initial fireball was a fuel-air explosion. If RP-1 leaked into the LOX tank and then vented with the GOX, all ingredients would be in place. It just needs a tiny spark for ignition.
I don't see how one tubular pipe can leak into another.
Some sort of welding flaw in the area where the common bulkhead meets the tank wall(s)? Yes, quite possibly - but I'd still expect to see at least some evidence of the vehicle body failing prior to the explosion; and also there should have been some trace on the telemetry.
For those of you looking for an ignition source please consider the Hurricane that was passing through Florida to the north. There were also many smaller t-storms spread all over. A t-storm can be 30 or 40 miles away and induce significant voltages in wiring or metal structures, especially those that are 200 ft+ high.Somebody posted the measurements from the field mills on the Cape.
Many years ago, 1973, in the Navy, we were anchored 2 miles offshore near Naples, Italy, for a medivac operation. The CO wanted to send a radio message, but we had no luck. I was ordered aloft to inspect the antennas at the top of the superstructure of the ship, about 120 feet high. There was a lightning storm in the mountains, more than 30 miles distant. Every time I saw a distant lightning strike in the mountains the entire top of the ship lit up with brilliant Elmo's Fire and my hair literally stood on end. I got down below pretty darn quick. Please google Elmo's Fire if you've not heard of it. This is the reason NASA and the Range have restrictions on launches when there is t-storm activity or even just towering cumulus clouds.
For those of you looking for an ignition source please consider the Hurricane that was passing through Florida to the north. There were also many smaller t-storms spread all over. A t-storm can be 30 or 40 miles away and induce significant voltages in wiring or metal structures, especially those that are 200 ft+ high.Somebody posted the measurements from the field mills on the Cape.
Many years ago, 1973, in the Navy, we were anchored 2 miles offshore near Naples, Italy, for a medivac operation. The CO wanted to send a radio message, but we had no luck. I was ordered aloft to inspect the antennas at the top of the superstructure of the ship, about 120 feet high. There was a lightning storm in the mountains, more than 30 miles distant. Every time I saw a distant lightning strike in the mountains the entire top of the ship lit up with brilliant Elmo's Fire and my hair literally stood on end. I got down below pretty darn quick. Please google Elmo's Fire if you've not heard of it. This is the reason NASA and the Range have restrictions on launches when there is t-storm activity or even just towering cumulus clouds.
Can you explain the missing beams, broken off, as opposed to heated and distorted by a fireball? Why would a strut in compression by a simple 10 tonne weight break off. Why was one grabber only distorted?
There are three things required: a fuel, an oxidizer, and an ignition source. It seems most of the folks posting theories are focusing on whichever of the three they like most and ignoring or wildly hand-waving about the rest.
Suppose there was lox-saturated frost on the rocket. Then what?
Suppose the a hole is poked in the tank. Then what?
Remember, all three have to occur either simultaneously or invisibly, since there was no prior indication before the explosion.
Further, (im)probabilities multiply. So if you postulate a highly unlikely source for one of the three, it seems your burden is much higher for showing that the other two are quite likely/common.
I feel there are a few plausable minor explanations for fuel- the strongback hydraulics, the RP1 tank, the stage 2 gimbal hydrolics- that only need a few coincidences to happen.
Oxidiser is dead simple. Lox-Frost shouldnt even be nessisary for the fuel sources I feel are most likely. If a leak is under sufficent pressure to aerosolize the fuel, a FAE can develop with normal air.
The problem, I feel, is ignition source. There's no electrical events and no heat sources in that area, by design. Someone suggesed a one-in-a-million solar mirror ignition- while unlikely, it should be relatively simple (though not easy) to retroactively prove or disprove, as we've got a bazilion pictures of the erector.
I find that theory unlikely, but what ignition sources -are- plausable?
I agree with the initial quoted post.
Unless something remarkably strange has happened, we need oxidiser, fuel and an ignition source.
We have the oxidiser if the tank is venting - an oxygen-rich environment.
We potentially have the ignition source on the erector: there is part of the air conditioning system at the height the explosion was *probably* initiated.
Okay, it will be guarded against sparking but it's not beyond reasonable suspicion that there could be a bare wire shorting or a motor that's not shielded properly and that *could* be the source.
In any instance, an ignition source is potentially the easiest mistake to have been made: the TEL is a 'Heath Robinson' of a device, which has been modified for three iterations of launch vehicle and certainly isn't what you'd build if you had a clean start (see the ones at Vandenberg and Pad 39a for comparison).
The bit that bothers me is the fuel - I don't quite see where it's come from; and I'm not easily persuaded by (for example) strangely flammable paint that SpaceX didn't realise they were applying; and that then requires some strange circumstances of oxygen liquifying out of the air.
The hydraulic fluid is possibly a candidate, but only if the claw system uses hydraulics (not pneumatics); and if the fluid is not flammable (less likely).
The hypothetical hydraulic system has a few aspects which make it a candidate for me:
- the leak can be above the point of initiation of the explosion, allowing fluid to fall down beside the vehicle in the area where the initial explosion happened
- the leak can also be upwind of the vehicle, enabling ignition within the frame of the erector frame and an explosion which is centred between the vehicle and the strongback (which corresponds with what was seen)
- the hydraulic system is probably the highest pressure fluid on the pad, so a tiny leak in a hose or fitting (not uncommon unless pipes and fittings are tested / changed regularly) will almost inevitably cause a fine mist
- there is less likely to be telemetry watching hydraulic pressures (and if the system at the top of the strongback is fed from the high-volume system that raises and lowers the erector, any pressure drop would be negligible)
(By way of comparison, the RP-1 tank considered against these counts:
- the leak would be below the point of initiation of the explosion
- the leak would have to blow into the wind to find the ignition source and this plume would almost certainly have been visible
- pressure in the tank is unlikely to produce a fine enough vapour to ignite, although in an oxygen-rich environment, the bar may be set quite low on the vapour front
- telemetry should show any significant leaks
The one thing I might entertain is the connections / equipment on the strongback that provides the feed to the upper stage - these are a bit low to correspond with the apparent point of initiation of the explosion, but sufficient pressure might allow fine fuel to be be squirted upwards.)
Can you explain the missing beams, broken off, as opposed to heated and distorted by a fireball? Why would a strut in compression by a simple 10 tonne weight break off. Why was one grabber only distorted? If it was all destroyed by the blast why was the blast selective between neighbouring struts and beams?
Missing beams?
If you're referring to the collapsed section of the strongback, that's the weakest point - where what appears to be bottlescrews were used to enable the transition (expansion in height) from F9 1.1 to F9 FT.
Plus, it got bent when it had to hold the weight of the payload after the rocket had weakened it by exploding pretty much exactly at that point.
I don't see how one tubular pipe can leak into another.
Can you explain the missing beams, broken off, as opposed to heated and distorted by a fireball? Why would a strut in compression by a simple 10 tonne weight break off. Why was one grabber only distorted?
Because the payload and fairing were sitting on it, after the second stage disappeared.
Or did the strongback fail first, and cause the blast.
Why would a 5 tonne satellite and fairing destroy all the turnbuckles and two welded beams? The same turnbuckles and beams, that lift it from horizontal along with a part of the dry weight of the Falcon 9. If they were so weak not to handle the offset when vertical, how did it get vertical?
I could see the grabbers distorting as they were outside their intended use. But the main connections in the strongback should have held. It means it was damaged at the turnbuckle area long before the fall. The initial blast does move the strongback and the fairing in the video. This would have been a twisting force. Did the blast break the strongback?
Can you explain the missing beams, broken off, as opposed to heated and distorted by a fireball? Why would a strut in compression by a simple 10 tonne weight break off. Why was one grabber only distorted?
Because the payload and fairing were sitting on it, after the second stage disappeared.
Why would a 5 tonne satellite and fairing destroy all the turnbuckles and two welded beams?
Heat flux, blast wave ...
Heat flux, blast wave ...
That is my point. It was not the satellite.
The discussion of FAE, hydraulic fluid and RP-1 spraying leaks and LOX on the outside of the vehicle is over.
SpaceX would have said something if they knew the source of the accident and now were just working on the cause.
Heat flux, blast wave ...
That is my point. It was not the satellite.
That means, if something changed on the 1-2 foot range, in the field of view of the camera, in the last 20 seconds prior to the event, we have a chance of seeing it.
Heat flux, blast wave ...
That is my point. It was not the satellite.
Absent the weight of the payload, those factors wouldn't have made any difference. That is everyone else's point.
That means, if something changed on the 1-2 foot range, in the field of view of the camera, in the last 20 seconds prior to the event, we have a chance of seeing it.
All that would be a waste, because there is nothing to see since nothing changed and hence the problem that Spacex has
Spacex has many more cameras views. There is no need to work on this one from this distance.
Heat flux, blast wave ...
That is my point. It was not the satellite.
Absent the weight of the payload, those factors wouldn't have made any difference. That is everyone else's point.
Simply 5 tonnes extra and it was enough to tip the destructive balance. No, I do not see that.
.That means, if something changed on the 1-2 foot range, in the field of view of the camera, in the last 20 seconds prior to the event, we have a chance of seeing it.
All that would be a waste, because there is nothing to see since nothing changed and hence the problem that Spacex has
Spacex has many more cameras views. There is no need to work on this one from this distance.
Unless Spacex used this process on the many more camera views, they wouldn't know either.
There are three things required: a fuel, an oxidizer, and an ignition source. It seems most of the folks posting theories are focusing on whichever of the three they like most and ignoring or wildly hand-waving about the rest.I think this type of theorizing is useful. Although there is plenty of oxidizer, there should be no fuel and no ignition source. If one person can explain how there might be fuel (while ignoring the ignition part) and another can explain how an ignition source could arise (while ignoring how the fuel got there) it would represent significant progress.
That means, if something changed on the 1-2 foot range, in the field of view of the camera, in the last 20 seconds prior to the event, we have a chance of seeing it.
All that would be a waste, because there is nothing to see since nothing changed and hence the problem that Spacex has
Spacex has many more cameras views. There is no need to work on this one from this distance.
Unless Spacex used this process on the many more camera views, they wouldn't know either.
Don't need it. It is very obvious to see changes in close ups
Essentially. My conjecture is that the frozen RP1, either through mechanical agitation in the boiling LOX or because it was atomized by Bernoulli in the LOX pipe, was blown out the vent as a cloud of fine particles, some of which had LOX either incorporated internally or wetting the surface.You mean, that the stage then vented a fuel-gox mix, ready to explode?No. It needs too many miracles to happen in succession.Not an especially strong argument.
The only fault I'm suggesting is a leak into the LOX line. After that, the stage has a situation of heavily hydrocarbon contaminated LOX which is an explosion waiting to happen.
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1582381#msg1582381 (http://forum.nasaspaceflight.com/index.php?topic=30981.msg1582381#msg1582381)
I think we need another sensible voice here besides Jim. Everyone else seems to be going off on weird tangents.
First, the explosion started at the junction of the S2 RP-1 and LOX tanks and the fireball burst outward on the WINDWARD side, adjoining the transporter/erector ("strongback"). The TEL is a thin lattice structure which would not stop the strong wind from scrubbing away the postulated leaking RP-1, etc. The only place that an explosive mixture of vapors could accumulate is in the turbulent eddy zone to LEEWARD of the booster (see the big external explosion that wrecked DC-X). The rapid dispersal of tank fragments further confirms that this was a internal explosion, not a DC-X type scenario.
Second, this type of accident is unknown in modern times with all other types of boosters, so we need to look for a unique feature of Falcon 9 which would fail in a unique way.
The glaringly obvious unique feature is the submerging of "composite" pressure vessels in supercooled liquid oxygen. British engineers call this material Carbon Reinforced Plastic (CRP) which is a more accurate description. Both the carbon fibers and the plastic/epoxy matrix are organic materials. The Falcon 9 design breaks a fundamental rule of rocket safety: no organic material must ever come in contact with LOX. As far as I know, every other modern rocket using CRP bottles for GHe or GN2 keeps them outside the propellant tanks. Those models using submerged tanks have stuck with titanium tanks.
The most famous case where this rule was broken was in 1951-53 when FOUR aircraft in the Bell X-1 and X-2 families blew up for no apparent reason. The LOX systems in these planes used LEATHER gaskets impregnated with WAX.
I don't know how Musk and his engineers convinced themselves that this configuration is safe. Possibly they put some inert coating on the outside of the bottles. But all the photos I have seen show them to be glossy black on the outside, like bare CRP.
Actually, we don't need actual combustion to explain the initial fireball. The He bottles are located right at the bottom of the LOX tank and a simple bursting of one would breach the common bulkhead and the outer skin at the same time.
Remember that the NASA investigators of the previous F9 S2 failure found photos of SpaceX assemblers STANDING on the He bottles - a great way to damage the outer surface after inspection.
You conspiracy buffs are now saying "Why didn't SpaceX already determine this from telemetry?" Granted that they actually have 3000 channels of telemetry and high-speed videos, I think they suffer from the same problem as the SpaceX amazing peoples on this thread - they are emotionally unable to admit that F9 has a fundamental design error that will require a long time to fix.
Look at the implications of this theory: All the first stages and second stages in production have to be redesigned and rebuilt. All the recovered first stages have to be rebuilt before they can be reused. I know I would have a hard time telling this to Elon if he were my boss.
Look at the implications of this theory: All the first stages and second stages in production have to be redesigned and rebuilt. All the recovered first stages have to be rebuilt before they can be reused. I know I would have a hard time telling this to Elon if he were my boss.Then you have no business being on a failure board. Would you rather explain to him why his NEXT rocket blew up, and then when the real problem comes out (as it eventually will) explain to him that you knew all along, and did not tell him?
It was closer to 10 tons and it fell. There is an acceleration involved.
It broke a turnbuckle in compression
Ok. Can you explain furthur where this vent would be on the Falcon 9?Tanks were not at flight pressure, but if the tank was slightly overfilled, there would be some purely internally generated pressure as subcooled Rp1 warmed up. Tanks would of course be designed to withstand this, for days on end, or it would be considered a fault. It would show up on the sensors, but be within tolerance. Because Acceptable Tolerance is a thing.
What would that pressure be? I do not know. What IS the expansion of subcooled RP1? Wound it be enough that a pinhole tank leak could cause aerosolization? That is my unproven assertion.
No, the tank is not closed. It is still vented
.
.
.
Look at the implications of this theory: All the first stages and second stages in production have to be redesigned and rebuilt. All the recovered first stages have to be rebuilt before they can be reused. I know I would have a hard time telling this to Elon if he were my boss.
Especially if Elon, as Chief Designer, was the one who insisted on that approach in the first place.
It was already grabbed at the top of the tank.
Through a set of grabbers that you earlier were certain would allow no movement.
Everyone else seems to be going off on weird tangents.
Soup to nuts in 16 milliseconds? That's fast... like amazingly fast. Like re-write the history of exploding rockets... but... I'm an imaging guru, not an exploding rocket guru.
I think we need another sensible voice here besides Jim. Everyone else seems to be going off on weird tangents.
First, the explosion started at the junction of the S2 RP-1 and LOX tanks and the fireball burst outward on the WINDWARD side, adjoining the transporter/erector ("strongback"). The TEL is a thin lattice structure which would not stop the strong wind from scrubbing away the postulated leaking RP-1, etc. The only place that an explosive mixture of vapors could accumulate is in the turbulent eddy zone to LEEWARD of the booster (see the big external explosion that wrecked DC-X). The rapid dispersal of tank fragments further confirms that this was a internal explosion, not a DC-X type scenario.
Second, this type of accident is unknown in modern times with all other types of boosters, so we need to look for a unique feature of Falcon 9 which would fail in a unique way.
The glaringly obvious unique feature is the submerging of "composite" pressure vessels in supercooled liquid oxygen. British engineers call this material Carbon Reinforced Plastic (CRP) which is a more accurate description. Both the carbon fibers and the plastic/epoxy matrix are organic materials. The Falcon 9 design breaks a fundamental rule of rocket safety: no organic material must ever come in contact with LOX. As far as I know, every other modern rocket using CRP bottles for GHe or GN2 keeps them outside the propellant tanks. Those models using submerged tanks have stuck with titanium tanks.
The most famous case where this rule was broken was in 1951-53 when FOUR aircraft in the Bell X-1 and X-2 families blew up for no apparent reason. The LOX systems in these planes used LEATHER gaskets impregnated with WAX.
I don't know how Musk and his engineers convinced themselves that this configuration is safe. Possibly they put some inert coating on the outside of the bottles. But all the photos I have seen show them to be glossy black on the outside, like bare CRP.
Actually, we don't need actual combustion to explain the initial fireball. The He bottles are located right at the bottom of the LOX tank and a simple bursting of one would breach the common bulkhead and the outer skin at the same time.
Remember that the NASA investigators of the previous F9 S2 failure found photos of SpaceX assemblers STANDING on the He bottles - a great way to damage the outer surface after inspection.
You conspiracy buffs are now saying "Why didn't SpaceX already determine this from telemetry?" Granted that they actually have 3000 channels of telemetry and high-speed videos, I think they suffer from the same problem as the SpaceX amazing peoples on this thread - they are emotionally unable to admit that F9 has a fundamental design error that will require a long time to fix.
Look at the implications of this theory: All the first stages and second stages in production have to be redesigned and rebuilt. All the recovered first stages have to be rebuilt before they can be reused. I know I would have a hard time telling this to Elon if he were my boss.
One alternative I've not seen addressed is a possibility for (c), an ignition source. This might be static buildup from the flow of insulating liquid. This is a known problem (http://www.machinerylubrication.com/Read/809/electrostatic-charge-hydraulic)that depends on flow rates, liquid properties, and so on. Since both kerosene and LOX are insulating liquids, I'd assume this was already addressed in the existing art. But sub-cooled LOX will have different properties, and SpaceX is pumping it at different rates, so maybe the old prevention techniques are insufficient.
One alternative I've not seen addressed is a possibility for (c), an ignition source. This might be static buildup from the flow of insulating liquid. This is a known problem (http://www.machinerylubrication.com/Read/809/electrostatic-charge-hydraulic)that depends on flow rates, liquid properties, and so on. Since both kerosene and LOX are insulating liquids, I'd assume this was already addressed in the existing art. But sub-cooled LOX will have different properties, and SpaceX is pumping it at different rates, so maybe the old prevention techniques are insufficient.
Well, it was raised by me some 1870-something posts back..
https://forum.nasaspaceflight.com/index.php?topic=30981.msg1576917#msg1576917 (https://forum.nasaspaceflight.com/index.php?topic=30981.msg1576917#msg1576917)
..but thank you for raising it again. 8)
One alternative I've not seen addressed is a possibility for (c), an ignition source. This might be static buildup from the flow of insulating liquid. This is a known problem (http://www.machinerylubrication.com/Read/809/electrostatic-charge-hydraulic)that depends on flow rates, liquid properties, and so on. Since both kerosene and LOX are insulating liquids, I'd assume this was already addressed in the existing art. But sub-cooled LOX will have different properties, and SpaceX is pumping it at different rates, so maybe the old prevention techniques are insufficient.
Well, it was raised by me some 1870-something posts back..
https://forum.nasaspaceflight.com/index.php?topic=30981.msg1576917#msg1576917 (https://forum.nasaspaceflight.com/index.php?topic=30981.msg1576917#msg1576917)
..but thank you for raising it again. 8)
Did we establish how the second stage is grounded? The major points of contact (interstage, gripper pads) seem to be insulative.
One alternative I've not seen addressed is a possibility for (c), an ignition source. This might be static buildup from the flow of insulating liquid. This is a known problem (http://www.machinerylubrication.com/Read/809/electrostatic-charge-hydraulic)that depends on flow rates, liquid properties, and so on. Since both kerosene and LOX are insulating liquids, I'd assume this was already addressed in the existing art. But sub-cooled LOX will have different properties, and SpaceX is pumping it at different rates, so maybe the old prevention techniques are insufficient.
Well, it was raised by me some 1870-something posts back..
https://forum.nasaspaceflight.com/index.php?topic=30981.msg1576917#msg1576917 (https://forum.nasaspaceflight.com/index.php?topic=30981.msg1576917#msg1576917)
..but thank you for raising it again. 8)
Did we establish how the second stage is grounded? The major points of contact (interstage, gripper pads) seem to be insulative.
Wouldn't there have to be a designed-in conductive path from the second stage thought the interstage to the first stage to keep all structure at the same potential during ascent?
The top of the tank with fairing and payload would be shoved up some distance by the explosion before falling onto the one gripper.
Through a set of grabbers that you earlier were certain would allow no movement.
Side to side movement. Never said anything about vertical. I would expect somebody on this forum to know that there is need to allow for vertical movement due to cryogenic contraction.
I think we need another sensible voice here besides Jim. Everyone else seems to be going off on weird tangents.
However, I'm beginning to believe the LOX-soaked frost theory. ...
There are three things required: a fuel, an oxidizer, and an ignition source. It seems most of the folks posting theories are focusing on whichever of the three they like most and ignoring or wildly hand-waving about the rest.Guilty as charged.
...
Does anyone know what the "MVac Fuel Trim Valve Setup" is all about?? That is the only thing I noted in the timeline posted that may have been happening at the time of the bang.
Again nothing supports your claims.
1) The Russian NK-33 family engines do use subcooled LOX (partly to cool the turbopump bearings better) but apparently not as low as 77 K. According to Spaceflight101 at http://spaceflight101.com/spacerockets/soyuz-2-1v/ the N-1 cooled to 81 K, Antares-100 to 78 K and the current Soyuz 2-1v to 86 K. Since these are all above 77 K, atmospheric LOX could never condense on the outside of their tanks, insulated or not. Is it possible that the Antares-100 temperature of 78 K was chosen with this in mind? Anybody know? So there is not much industry experience with sub-77 LOX.
...
Does anyone know what the "MVac Fuel Trim Valve Setup" is all about?? That is the only thing I noted in the timeline posted that may have been happening at the time of the bang.
It's testing/calibrating the servo motor driven propellent fine control valves on the 2nd stage:
The fuel-trim device consists of a servo-motor-controlled butterfly valve. To achieve the proper speed and torque, the design incorporates a planetary gearbox for a roughly 151:1 reduction ratio, plus additional gearing internal to the unit. The team qualified the components with a significant safety margin to protect against common-mode failure. The shaft of the motor interfaces with the valve directly to make fine adjustments. “The basic mixture ratio is given by the sizing of the tubes, and a small amount of the flow of each one gets trimmed out,” explains Frefel. “We only adjust a fraction of the whole fuel flow.”
http://www.micromo.com/applications/aerospace-defense/space-x-shuttle-launch
Again nothing supports your claims.
An understanding of truss design and load-path analysis, basic physics and the US Launch Report video support his claims.
1. It would also have to continue to sit there as the strongback turnbuckle areas collapsed.
2. As for the expansion that was immediately pointed out to you by a subsequent post by another when you claimed no movement could occur. Now we are told that these pads allow movement, but only in one direction. There could never be side to side movement at the lower pivot cradle pad anyway. That would require the Falcon 9 to twist. There was only up and down movement considered due to the pivot cradle.
Again nothing supports your claims.
The servo valves are much lower on the stage, near the Merlin. The failure happened halfway up the tank.
Thanks for that. Something else to add to the memory bank! :)
Where is was going with the enquiry was: Is a short-circuit - or fuel leakage causing brittle-fracture, total failure and then short circuit - of this servo-valve assembly a possible cause here? I've personally seen motorised cryogenic butterfly valves in industrial tank farms fail like this before (cheap ones on a Liquid Nitrogen system granted, but it did happen).
I want to try something else...
In regular fuel-air explosion, you need to disperse the fuel very finely in "3D" to get a good burning mixture.
But here, we have LOX.
What if... this is a surface phenomena, not a volume phenomena.
- It is very well coupled to the skin, so a much smaller amount of reactants might be able to damage the tank
- It might help with the wind conundrum.
- It will occur right on the wall, which kinda sorta maybe fits the video.
3) One thing in favour of the theory is that it's so easily testable in practice; a spare tank, some subcooled LOX, and a lot of days with different weather. But of course SpaceX may already have done all that, have temperature sensors all over the outer skin, and measurements to show that the outer surface of the paint never gets down anywhere near 77 K.
Actually, we don't need actual combustion to explain the initial fireball. The He bottles are located right at the bottom of the LOX tank and a simple bursting of one would breach the common bulkhead and the outer skin at the same time.
How can you be sure that a failed COPV would breach either the CB or outer wall or both? How can you be sure it would mix and explode with LOX?
Thanks for that. Something else to add to the memory bank! :)
Where is was going with the enquiry was: Is a short-circuit - or fuel leakage causing brittle-fracture, total failure and then short circuit - of this servo-valve assembly a possible cause here? I've personally seen motorised cryogenic butterfly valves in industrial tank farms fail like this before (cheap ones on a Liquid Nitrogen system granted, but it did happen).
The servo valves are much lower on the stage, near the Merlin. The failure happened halfway up the tank.
To start with, the LOX line I'm talking about is the line that runs from the LOX tank through the fuel tank to get to the engine. When the stage is being fueled, the pressure in both the LOX and RP1 tank is going to be very similar because they are separated by a common bulkhead.
RP1 will certainly float not sink in LOX, it is significantly less dense.
1. It would also have to continue to sit there as the strongback turnbuckle areas collapsed.
2. As for the expansion that was immediately pointed out to you by a subsequent post by another when you claimed no movement could occur. Now we are told that these pads allow movement, but only in one direction. There could never be side to side movement at the lower pivot cradle pad anyway. That would require the Falcon 9 to twist. There was only up and down movement considered due to the pivot cradle.
Again nothing supports your claims.
wrong.
1. It did sit there. It was 8 seconds from the beginning of the explosion until the appearance of the fairing tipping over.
2. The movement is the vehicle shrinking. So the vehicle is sliding against the pads in the gripper and cradle. The cradle pivot is not involved. The cradle is for when the vehicle is horizontal. Earlier strongback versions only had the gripper pads and the vehicle could not support the payload and fairing for long periods of time without supplemental support (crane and sling) while horizontal.
50 - 100 pounds of TNT!!!??? How did you arrive at anything near that number?I want to try something else...
In regular fuel-air explosion, you need to disperse the fuel very finely in "3D" to get a good burning mixture.
But here, we have LOX.
What if... this is a surface phenomena, not a volume phenomena.
- It is very well coupled to the skin, so a much smaller amount of reactants might be able to damage the tank
- It might help with the wind conundrum.
- It will occur right on the wall, which kinda sorta maybe fits the video.
You have to come up with the Stoichiometry of the fuel vs available oxygen.
If you assume RP1, Kerosine, Aluminum, bat guano, there is so much oxygen required to consume your fuel.
Deeper in this thread I provided the calculations for Kerosine, which is well studied.
I also provided an analysis of the frame 1 fireball.
Here's the basics:
1. The frame 1 fireball is equivalent to 50-100 lb of tnt. Analysis previously provided in this thread.
2. If the detonation were FEA kerosine, that would have required .4 kg of kerosine. Kerosine is not RP-1, but it's close. It would have to be a perfect aerosol before the gremlin lit the match. Analysis previously provided in this thread.
3. Any other ignition source has to produce equivalent stoichiometry equivalent to 50-100 lb of tnt. Aluminum and paint are not in the running. Nor is bird poop, iphones, lithium batteries, cork, seagulls, whatever.
4. Frame 1 requires about 52 x 10^6 joules of energy to be consistent with that image. Any hypothesis has to be able to produce this amount of energy. Sherwin Williams is off the chart. LOX, GOX, etc, is not a fuel. You have to find a fuel that burns with that energy release in 16 milliseconds. It doesn't matter if the oxygen is enriched, depleted, or drooling down the side of the rocket. You need fuel that when combusted with air or enriched oxygen air, or dribbled by the nearest seagull or UFO, produces the requisite energy by BURNING the fuel. IF you can't find the fuel, there is no explosion, and this never happened.
We have to find a means of producing 52 x 10^6 joules of energy, thereabouts, to identify the cause of this event. My guesstimates are plus minus 50%
3) One thing in favour of the theory is that it's so easily testable in practice; a spare tank, some subcooled LOX, and a lot of days with different weather. But of course SpaceX may already have done all that, have temperature sensors all over the outer skin, and measurements to show that the outer surface of the paint never gets down anywhere near 77 K.
don't need to test it, just look at past missions. No LOX soaked frost layer
With all due respect, the argument "In the ten previous trials, this effect never showed up" is evidence, but not sound engineering. It could have been said in many, many previous failures, with respect to the cause that was eventually determined.
3) One thing in favour of the theory is that it's so easily testable in practice; a spare tank, some subcooled LOX, and a lot of days with different weather. But of course SpaceX may already have done all that, have temperature sensors all over the outer skin, and measurements to show that the outer surface of the paint never gets down anywhere near 77 K.
don't need to test it, just look at past missions. No LOX soaked frost layer
50 - 100 pounds of TNT!!!??? How did you arrive at anything near that number?I want to try something else...
In regular fuel-air explosion, you need to disperse the fuel very finely in "3D" to get a good burning mixture.
But here, we have LOX.
What if... this is a surface phenomena, not a volume phenomena.
- It is very well coupled to the skin, so a much smaller amount of reactants might be able to damage the tank
- It might help with the wind conundrum.
- It will occur right on the wall, which kinda sorta maybe fits the video.
You have to come up with the Stoichiometry of the fuel vs available oxygen.
If you assume RP1, Kerosine, Aluminum, bat guano, there is so much oxygen required to consume your fuel.
Deeper in this thread I provided the calculations for Kerosine, which is well studied.
I also provided an analysis of the frame 1 fireball.
Here's the basics:
1. The frame 1 fireball is equivalent to 50-100 lb of tnt. Analysis previously provided in this thread.
2. If the detonation were FEA kerosine, that would have required .4 kg of kerosine. Kerosine is not RP-1, but it's close. It would have to be a perfect aerosol before the gremlin lit the match. Analysis previously provided in this thread.
3. Any other ignition source has to produce equivalent stoichiometry equivalent to 50-100 lb of tnt. Aluminum and paint are not in the running. Nor is bird poop, iphones, lithium batteries, cork, seagulls, whatever.
4. Frame 1 requires about 52 x 10^6 joules of energy to be consistent with that image. Any hypothesis has to be able to produce this amount of energy. Sherwin Williams is off the chart. LOX, GOX, etc, is not a fuel. You have to find a fuel that burns with that energy release in 16 milliseconds. It doesn't matter if the oxygen is enriched, depleted, or drooling down the side of the rocket. You need fuel that when combusted with air or enriched oxygen air, or dribbled by the nearest seagull or UFO, produces the requisite energy by BURNING the fuel. IF you can't find the fuel, there is no explosion, and this never happened.
We have to find a means of producing 52 x 10^6 joules of energy, thereabouts, to identify the cause of this event. My guesstimates are plus minus 50%
Have you ever seen even a pound of TNT explode? 50 to 100 pounds would have blown the entire second stage to bits.
Precisely.To start with, the LOX line I'm talking about is the line that runs from the LOX tank through the fuel tank to get to the engine. When the stage is being fueled, the pressure in both the LOX and RP1 tank is going to be very similar because they are separated by a common bulkhead.
RP1 will certainly float not sink in LOX, it is significantly less dense.
Remember, RP1 is loaded first, and then LOX. But neither tank is pressurized until late in the count after both tanks are full.
Precisely.To start with, the LOX line I'm talking about is the line that runs from the LOX tank through the fuel tank to get to the engine. When the stage is being fueled, the pressure in both the LOX and RP1 tank is going to be very similar because they are separated by a common bulkhead.
RP1 will certainly float not sink in LOX, it is significantly less dense.
Remember, RP1 is loaded first, and then LOX. But neither tank is pressurized until late in the count after both tanks are full.
There's no pressure to prevent RP1 leaking from the full tank into the empty LOX line running through it before the LOX loading started.
Thanks for that. Something else to add to the memory bank! :)
Where is was going with the enquiry was: Is a short-circuit - or fuel leakage causing brittle-fracture, total failure and then short circuit - of this servo-valve assembly a possible cause here? I've personally seen motorised cryogenic butterfly valves in industrial tank farms fail like this before (cheap ones on a Liquid Nitrogen system granted, but it did happen).
The servo valves are much lower on the stage, near the Merlin. The failure happened halfway up the tank.
Oh well.. What else is halfway up the tank then? Can't be too many things to rule out.
I think Cameron's claim was that the servo might have overheated/shorted and started a fire. But you're right, there would be little fuel for that fire at that point. And my point was that the evidence of the fire would first show up near the engine/in the interstage, not halfway up the second stage.
Thanks for that. Something else to add to the memory bank! :)
Where is was going with the enquiry was: Is a short-circuit - or fuel leakage causing brittle-fracture, total failure and then short circuit - of this servo-valve assembly a possible cause here? I've personally seen motorised cryogenic butterfly valves in industrial tank farms fail like this before (cheap ones on a Liquid Nitrogen system granted, but it did happen).
The servo valves are much lower on the stage, near the Merlin. The failure happened halfway up the tank.
Oh well.. What else is halfway up the tank then? Can't be too many things to rule out.
The trim valve, as it's name implies, only trims the flow. It is not the main propellent valving and doesn't work against full tank pressure, and AFAIK is not wet at this point in the count (i.e. it's downstream of the main valves).
Thanks for that. Something else to add to the memory bank! :)
Where is was going with the enquiry was: Is a short-circuit - or fuel leakage causing brittle-fracture, total failure and then short circuit - of this servo-valve assembly a possible cause here? I've personally seen motorised cryogenic butterfly valves in industrial tank farms fail like this before (cheap ones on a Liquid Nitrogen system granted, but it did happen).
The servo valves are much lower on the stage, near the Merlin. The failure happened halfway up the tank.
Oh well.. What else is halfway up the tank then? Can't be too many things to rule out.
The trim valve, as it's name implies, only trims the flow. It is not the main propellent valving and doesn't work against full tank pressure, and AFAIK is not wet at this point in the count (i.e. it's downstream of the main valves).
Precisely.To start with, the LOX line I'm talking about is the line that runs from the LOX tank through the fuel tank to get to the engine. When the stage is being fueled, the pressure in both the LOX and RP1 tank is going to be very similar because they are separated by a common bulkhead.
RP1 will certainly float not sink in LOX, it is significantly less dense.
Remember, RP1 is loaded first, and then LOX. But neither tank is pressurized until late in the count after both tanks are full.
There's no pressure to prevent RP1 leaking from the full tank into the empty LOX line running through it before the LOX loading started.
Although I'm one who doesn't believe that's possible, for reasons discussed >1700 posts ago..
What if they inadvertently overfilled the RP1 tank and didn't notice? Perhaps it's a closed system and the question is moot, but where do the fuel drains go??
Actually, we don't need actual combustion to explain the initial fireball. The He bottles are located right at the bottom of the LOX tank and a simple bursting of one would breach the common bulkhead and the outer skin at the same time.
How can you be sure that a failed COPV would breach either the CB or outer wall or both? How can you be sure it would mix and explode with LOX?
I'm not the original poster, but keep in mind that SpaceX is on record as believing a COPV failure could cause a structural failure in CRS-7.
Jim has indicated that the tanks remain vented to ambient pressure until they are pressurized late in the count. Drains, as I understand it, are back down the umbilicals into the GSE. Not exactly sure how the vents are designed but either fluid would flow out a vent (and should be visible in SpaceX's internal closeup imagery from the pad) or the GSE would register increased system pressure and load on the pumps (reduced RPM on the pump shaft, increased motor temp or current draw, decreased flow rate, increased pressure, whatever). But more to the point, RP1 load finishes fairly early in the count (T-22 minutes for S2), with plenty of time to notice and do something about it.
Jim has indicated that the tanks remain vented to ambient pressure until they are pressurized late in the count. Drains, as I understand it, are back down the umbilicals into the GSE. Not exactly sure how the vents are designed but either fluid would flow out a vent (and should be visible in SpaceX's internal closeup imagery from the pad) or the GSE would register increased system pressure and load on the pumps (reduced RPM on the pump shaft, increased motor temp or current draw, decreased flow rate, increased pressure, whatever). But more to the point, RP1 load finishes fairly early in the count (T-22 minutes for S2), with plenty of time to notice and do something about it.
So there could (theoretically) be residual RP1 in the tank drain lines and umbilicals during LOX filling?? Interesting.
I wonder if they have any electrically-operated isolation valves on their RP1 drain lines anywhere near the location of the bang..
Jim has indicated that the tanks remain vented to ambient pressure until they are pressurized late in the count. Drains, as I understand it, are back down the umbilicals into the GSE. Not exactly sure how the vents are designed but either fluid would flow out a vent (and should be visible in SpaceX's internal closeup imagery from the pad) or the GSE would register increased system pressure and load on the pumps (reduced RPM on the pump shaft, increased motor temp or current draw, decreased flow rate, increased pressure, whatever). But more to the point, RP1 load finishes fairly early in the count (T-22 minutes for S2), with plenty of time to notice and do something about it.
So there could (theoretically) be residual RP1 in the tank drain lines and umbilicals during LOX filling?? Interesting.
I wonder if they have any electrically-operated isolation valves on their RP1 drain lines anywhere near the location of the bang..
The umbilicals connect to the interstage down by the Merlin. Also not particularly near the bang.
So there could (theoretically) be residual RP1 in the tank drain lines and umbilicals during LOX filling?? Interesting.
So there could (theoretically) be residual RP1 in the tank drain lines and umbilicals during LOX filling?? Interesting.
I don't think that necessarily follows. The tanks undoubtedly have check or isolation valves at their umbilical plates, and there may or may not be valves at the base of the tower and check valve/vents to allow the residuals to drain back down to the base of the T/E and out of the system I don't know, but I'd be very surprised if there was any significant volume of RP1 left in the system, let alone under any pressure.
1. I know it did sit there. That was my claim. How it did that, after your claim of it bouncing down onto two grabbers using the failed skin of an fully exploded tank wall to keep alignment is what I was countering. It sat there because it was always there, and was held there.
2. The cradle is not only for when the vehicle is horizontal otherwise they would have put the pads on the grabbers at the front and back. Not just the sides and the front. The video close up of the CRS-8 retract proves it is used when vertical.
Actually, we don't need actual combustion to explain the initial fireball. The He bottles are located right at the bottom of the LOX tank and a simple bursting of one would breach the common bulkhead and the outer skin at the same time.
How can you be sure that a failed COPV would breach either the CB or outer wall or both? How can you be sure it would mix and explode with LOX?
I'm not the original poster, but keep in mind that SpaceX is on record as believing a COPV failure could cause a structural failure in CRS-7.
CRS-7 had a full COPV in a full LOX tank (<5% ullage) under flight loads at flight pressures and it didn't burst or ignite. This was a partially empty COPV in a partially empty LOX tank (>30% ullage) with no internal pressure and no dynamic loads, and it didn't just burst but also ignited, apparently in a few milliseconds and without warning.
It is far from obvious that a COPV failure would breach the tank under these circumstances. More evidence is needed to support that claim.
But fast fill means the sides are not in this state for long. I'd take a very close look at this if I was on the investigation board.
Look at past missions. Is there liquid on the outside of the stages?
And if there was LOX forming one the vehicle, it isn't going to mix with anything on the TEL. It would stream down onto the fuel tank portion of the vehicle and evaporate. It isn't going to contribute any more O2 to the environment than the GOX venting from the vehicle.
Precisely.To start with, the LOX line I'm talking about is the line that runs from the LOX tank through the fuel tank to get to the engine. When the stage is being fueled, the pressure in both the LOX and RP1 tank is going to be very similar because they are separated by a common bulkhead.
RP1 will certainly float not sink in LOX, it is significantly less dense.
Remember, RP1 is loaded first, and then LOX. But neither tank is pressurized until late in the count after both tanks are full.
There's no pressure to prevent RP1 leaking from the full tank into the empty LOX line running through it before the LOX loading started.
With all due respect, the argument "In the ten previous trials, this effect never showed up" is evidence, but not sound engineering. It could have been said in many, many previous failures, with respect to the cause that was eventually determined.
Attached is an image that shows where I think folks should concentrate if they believe that a visible event preceded the main show.
On the left is a compound image of the 70 turbulence stabilized frames, astrophotography technique. In the middle is the difference between that image and the single last pre-event turbulence stabilized image. On the right are the areas flagged, in yellow, where in my opinion, there are regions of interest.
Basically, the brighter the area in the difference map, the more it deviates from the normal.
We have a 1,200 frame turbulence removal in process, about 20 seconds worth, may be available tomorrow I'm told.
Sorry but noThe issue with pressure isn't if it's at ambient, it's if there is a pressure differential between the RP1 tank and LOX line where the LOX line is at higher pressure than the RP1 tank before LOX loading starts, thereby preventing leaking of RP1 into the LOX line.
there are blanket pressures. Yes, the tanks are vented but they are not vented to ambient. the vent valves have a cracking pressure.
And the LOX line is likely in another line for insulation
The issue with pressure isn't if it's at ambient, it's if there is a pressure differential between the RP1 tank and LOX line where the LOX line is at higher pressure than the RP1 tank before LOX loading starts, thereby preventing leaking of RP1 into the LOX line.
The construction of the LOX line is certainly a valid objection however. It must be insulated somehow, but I've not been able to find a description of how it's set up or what the coupling at the bottom RP1 bulkhead consists of. My conjecture does require a path for RP1 to get into the LOX tank which obviously is highly dependent on the exact design of that pipe. There could be other paths from below the RP1 surface into the LOX tank, but the LOX pipe is certainly the most obvious.
Sorry but noThe issue with pressure isn't if it's at ambient, it's if there is a pressure differential between the RP1 tank and LOX line where the LOX line is at higher pressure than the RP1 tank before LOX loading starts, thereby preventing leaking of RP1 into the LOX line.
there are blanket pressures. Yes, the tanks are vented but they are not vented to ambient. the vent valves have a cracking pressure.
And the LOX line is likely in another line for insulation
The construction of the LOX line is certainly a valid objection however. It must be insulated somehow, but I've not been able to find a description of how it's set up or what the coupling at the bottom RP1 bulkhead consists of. My conjecture does require a path for RP1 to get into the LOX tank which obviously is highly dependent on the exact design of that pipe. There could be other paths from below the RP1 surface into the LOX tank, but the LOX pipe is certainly the most obvious.
FWIW, RP1 getting into the LOX tank would rise to the top (away from the location of the bang), but be so chilled by the LOX such that you couldn't ignite it with a blowtorch.
I'm leaning more and more to the failed COPV scenario. The event happened, really, really fast. In 16 ms, the rocket went from sitting happily on the pad, to being enveloped by a fireball, and the simplest thing that could act that fast, that also makes sense is a COPV failure.
CRS 7:
Tanks at flight pressure, overpressure causes LOX tank to burst, aerodynamic stress causes RP1 tank to disintegrate, huge cloud of mist , LOX and RP1, but no fire until the mess comes in contact with 1st stage exhaust.
AMOS6:
LOX tank half full, neither tank pressurized. Yet sudden big fireball around LOX tank? Thats so unlikely, even if any of the tanks had sprouted a leak it would more likely have created a waterfall style outpour. Since the lox is subcooled it wouldnt even turn gaseous on exit like pressurized boiling lox, it would just pour.
I think that alone points at an external event.
Hello,
this has probably been asked before and i tried my best to search the thread, but didnt find anything to answer my question.
If this is a upper stage failure and it was a hot fire test (which is just testing the S1 booster), why was the upper stage fueled up? My guess it was fueled up or what exactly did combust there?
Attached is an image that shows where I think folks should concentrate if they believe that a visible event preceded the main show.
On the left is a compound image of the 70 turbulence stabilized frames, astrophotography technique. In the middle is the difference between that image and the single last pre-event turbulence stabilized image. On the right are the areas flagged, in yellow, where in my opinion, there are regions of interest.
Basically, the brighter the area in the difference map, the more it deviates from the normal.
We have a 1,200 frame turbulence removal in process, about 20 seconds worth, may be available tomorrow I'm told.
It appears that at least the three points of deviation on the left coincide with the cradle frame. So are you suggesting the cradle moved in the last frame before the fast fire?
Edit: If so, perhaps there is a design flaw with the cradle, especially when the rocket is vertical and subjected to transient loading from wind, e.g. vortex shedding. The lower pad is resting near the midpoint of the second stage, essentially creating a cantilever, and hence a stress concentrator. This effect is enhanced further when the grabber is engaged, because that pins the location of the top bulkhead. Because the cradle is also pinned, and the top pad is now fixed relative to the grabber, any flex in the rocket will be now concentrated at the lower pad. If the cradle extended to the base of the second stage, the lower pad could rest against the lower bulkhead, making the stage a pinned beam with far greater structural integrity.
This raises an interesting point, the video footage shows what happened, but effectively sampled every 16.7ms.
Soup to nuts in 16 milliseconds? That's fast... like amazingly fast. Like re-write the history of exploding rockets... but... I'm an imaging guru, not an exploding rocket guru.
The problem with an internal "soup to nuts in 16 mSec" event is that it would not cause a small bright flash that diminishes, and is followed by a much slower fire.
If something was able to do all that damage internally so quickly, it would follow that in the next 16 mSec, you'd have more LOX and propellant flying out and basically the event escalating.
Instead we see, very distinctly, a bright flash happening in frame 1, holding and diminishing for about 5 frames or so? and then the subsequent collapse (which could be a result of it, or the rest of the failure, happening in parallel).
Some posters have assumed that the center of the initial explosion must be at the geometric center of the first visible frame flash, which lies approximately at the boundary between the S2 RP1 and LOX tanks, however during the (up to 16.7ms) sampling interval, the flash could have started at the base of S2 then worked up tracing some extraneous fuel source, or vice-versa from the base of the fairing down.
This raises an interesting point, the video footage shows what happened, but effectively sampled every 16.7ms.
Soup to nuts in 16 milliseconds? That's fast... like amazingly fast. Like re-write the history of exploding rockets... but... I'm an imaging guru, not an exploding rocket guru.
The problem with an internal "soup to nuts in 16 mSec" event is that it would not cause a small bright flash that diminishes, and is followed by a much slower fire.
If something was able to do all that damage internally so quickly, it would follow that in the next 16 mSec, you'd have more LOX and propellant flying out and basically the event escalating.
Instead we see, very distinctly, a bright flash happening in frame 1, holding and diminishing for about 5 frames or so? and then the subsequent collapse (which could be a result of it, or the rest of the failure, happening in parallel).
What is observed in the USLaunchReport video footage is nothing significantly unusual in one frame, then a sudden visible bright flash running almost all the way from the base of S2 up to the fairing, then leading to the subsequent 'slower darker' FAE blooming into a massive fireball.
The initial explosion is very bright and it's possible that video camera lens flare/overexposure makes the initial flash appear larger than it actually was.
Some posters have assumed that the center of the initial explosion must be at the geometric center of the first visible frame flash, which lies approximately at the boundary between the S2 RP1 and LOX tanks, however during the (up to 16.7ms) sampling interval, the flash could have started at the base of S2 then worked up tracing some extraneous fuel source, or vice-versa from the base of the fairing down.
This raises an interesting point, the video footage shows what happened, but effectively sampled every 16.7ms.
Soup to nuts in 16 milliseconds? That's fast... like amazingly fast. Like re-write the history of exploding rockets... but... I'm an imaging guru, not an exploding rocket guru.
The problem with an internal "soup to nuts in 16 mSec" event is that it would not cause a small bright flash that diminishes, and is followed by a much slower fire.
If something was able to do all that damage internally so quickly, it would follow that in the next 16 mSec, you'd have more LOX and propellant flying out and basically the event escalating.
Instead we see, very distinctly, a bright flash happening in frame 1, holding and diminishing for about 5 frames or so? and then the subsequent collapse (which could be a result of it, or the rest of the failure, happening in parallel).
What is observed in the USLaunchReport video footage is nothing significantly unusual in one frame, then a sudden visible bright flash running almost all the way from the base of S2 up to the fairing, then leading to the subsequent 'slower darker' FAE blooming into a massive fireball.
The initial explosion is very bright and it's possible that video camera lens flare/overexposure makes the initial flash appear larger than it actually was.
Some posters have assumed that the center of the initial explosion must be at the geometric center of the first visible frame flash, which lies approximately at the boundary between the S2 RP1 and LOX tanks, however during the (up to 16.7ms) sampling interval, the flash could have started at the base of S2 then worked up tracing some extraneous fuel source, or vice-versa from the base of the fairing down.
...
Re the apparent shrinking... The event continues to expand during all relevant frames. What gives the illusion of shrinking is gaseous material is obscuring parts of the fireball and about 5 frames in there's a lot of gaseous junk in the field of view. If you measure the observable actual edges of the fireball, it's still expanding.
...
This raises an interesting point, the video footage shows what happened, but effectively sampled every 16.7ms.
Soup to nuts in 16 milliseconds? That's fast... like amazingly fast. Like re-write the history of exploding rockets... but... I'm an imaging guru, not an exploding rocket guru.
The problem with an internal "soup to nuts in 16 mSec" event is that it would not cause a small bright flash that diminishes, and is followed by a much slower fire.
If something was able to do all that damage internally so quickly, it would follow that in the next 16 mSec, you'd have more LOX and propellant flying out and basically the event escalating.
Instead we see, very distinctly, a bright flash happening in frame 1, holding and diminishing for about 5 frames or so? and then the subsequent collapse (which could be a result of it, or the rest of the failure, happening in parallel).
What is observed in the USLaunchReport video footage is nothing significantly unusual in one frame, then a sudden visible bright flash running almost all the way from the base of S2 up to the fairing, then leading to the subsequent 'slower darker' FAE blooming into a massive fireball.
The initial explosion is very bright and it's possible that video camera lens flare/overexposure makes the initial flash appear larger than it actually was.
Some posters have assumed that the center of the initial explosion must be at the geometric center of the first visible frame flash, which lies approximately at the boundary between the S2 RP1 and LOX tanks, however during the (up to 16.7ms) sampling interval, the flash could have started at the base of S2 then worked up tracing some extraneous fuel source, or vice-versa from the base of the fairing down.
...
Re the apparent shrinking... The event continues to expand during all relevant frames. What gives the illusion of shrinking is gaseous material is obscuring parts of the fireball and about 5 frames in there's a lot of gaseous junk in the field of view. If you measure the observable actual edges of the fireball, it's still expanding.
...
Not true. If the fireball was in contact with this cloud of condensate, this should have been illuminated, assuming, that the fireball was still growing. This was not the case.
I think it's not debatable that the initial flash died down for a few frames of the video before the main tank ruptures began the major fireball, as stage 2's tanks unzipped.
It seems to me we're seeing an external explosion and an initial cascade of LOX, that actually did nearly smother the fire due to blowing its fuel source away from the initial blast point. Of course, it being LOX, as soon as any sufficient fuel source entered the mix (i.e., when the RP-1 tank ruptured), the fireball expanded again.
This would argue towards the LOX tank rupturing first, and then the RP-1 tank. I believe this conclusion is reinforced by the observed cascade of unburned RP-1 coming down from the exploding second stage after the tanks were compromised. Had both tanks come apart at the same time, as a tank wall failure at the common bulkhead would have done, the turbulence of the explosion would have mixed a lot more of the RP-1 into the fireball and resulted in little to no unburned RP-1 falling down along the sides of the rocket, I think...
My first post. Please be gentle.. :)Welcome to the forum! :)
Does the umbilical for propellant feed to the upper stage provide both RP-1 and LOX?
If so...
Maybe the umbilical for the upper stage detached for some unknown reason. There would be pressure in the pipes feeding the propellants and quite possibly some back pressure (less than flight pressure) in the propellant tanks, too.
This would cause a spray/mist of RP-1 and LOX from the connection point. They would immediately mix and form a flammable cloud.
The connector separating would also provide a plausible ingition source, either by a mechanical or an electrical spark.
The resulting deflagaration would transition into a detonation almost instantly.
The detonation of a relatively large amount of material right next to the tanks would rupture them and everything would proceed downhill from there.
This all could happen in milliseconds, so it would not be readily evident in the video and it would also be difficult to tell the cause from the effect in the telemetry data.
But this scenario only "works" if the RP-1 and LOX feed lines are right next to each other.
Please shoot holes into this if you know something I don't, and sorry if this has been proposed earlier (quite many posts in this thread).
Some posters have assumed that the center of the initial explosion must be at the geometric center of the first visible frame flash, which lies approximately at the boundary between the S2 RP1 and LOX tanks, however during the (up to 16.7ms) sampling interval, the flash could have started at the base of S2 then worked up tracing some extraneous fuel source, or vice-versa from the base of the fairing down.
OK, this is my theory:I don't believe there is a vent for the RP1 that would be normally exhausting on the pad. The LOX vent is needed because the LOX is boiling during filling.
1) A (possibly tiny) leak in the common bulkhead lets LOX into the RP1 tank
2) LOX boils away and takes some of the RP1 with it
3) The GOX-RP1 mix exits through the RP1 tank vent and forms a highly explosive cloud right were the initial explosion was observed.
4) Something (a tiny spark is enough) ignites the mixture and the rest is history
This would explain:
* no apparent breach of the hull before the explosion
* the sudden blast
Problems:
* Could this get past the telemetry?
* Could the postulated GOX-RP1 cloud form under the wind conditions?
* Could the boiling LOX carry enough RP1?
I don't believe there is a vent for the RP1 that would be normally exhausting on the pad. The LOX vent is needed because the LOX is boiling during filling.
My first post. Please be gentle.. :)It is a common umbilical.
Does the umbilical for propellant feed to the upper stage provide both RP-1 and LOX?
If so...
Maybe the umbilical for the upper stage detached for some unknown reason. There would be pressure in the pipes feeding the propellants and quite possibly some back pressure (less than flight pressure) in the propellant tanks, too.
This would cause a spray/mist of RP-1 and LOX from the connection point. They would immediately mix and form a flammable cloud.
The connector separating would also provide a plausible ingition source, either by a mechanical or an electrical spark.
The resulting deflagaration would transition into a detonation almost instantly.
The detonation of a relatively large amount of material right next to the tanks would rupture them and everything would proceed downhill from there.
This all could happen in milliseconds, so it would not be readily evident in the video and it would also be difficult to tell the cause from the effect in the telemetry data.
But this scenario only "works" if the RP-1 and LOX feed lines are right next to each other.
Please shoot holes into this if you know something I don't, and sorry if this has been proposed earlier (quite many posts in this thread).
I've watched this video and the frames #0 - #3 also countless times so, that they've been burned to my retina already. I've convinced myself, that the initial blast originated in strongback. Not inside rocket, not on rocket body skin. Look at the attached image for approx location of initial bang. Here's why I think so:One serious problem with this scenario is that RP1 vapor at anywhere near room temperature won't ignite and certainly won't explode even with an open flame. It's not at all like gasoline.
1. Reflection on rocket body below is larger than above. There's at least is some reflection on payload fairing.
2. Those "claws" in left (frame #1) are streams of condensate, that scatter light. The same thing was possibly visible from the other side.
3. Also big part of the "flash" below is actually reflection from rocket body combined with condensate scattering
4. If the blast would have originated on rocket skin, we should not have seen those "claws". Also hints on the destruction of the S2 skin should have been visible
My take on what happened.
1. On umbilical connection with RP-1 main line, a pinhole leak developed
2. As the RP-1 is at least under pressure to reach the top of the tank (and then some to get realistic flowspeeds), then the jet should have reached at least the altitude of LOX tank on S2, giving us nice fountain, whose tip was directed towards leftmost corner of strongback near the rocket
3. The rocket is about 35pixels wide on the video. Thus, the stream to be visible, it should have had the width of at least half of a pixel (meaning approximately 2 in). In addition, the stream was hidden by the frame of the strongback
4. The stream wetted the strongback frame and the walkway (now standing vertical)
5. Heat transfer from surrounding air, strongback frame and walkway took subcooled RP-1 back to vaporization temperatures
6. Warm wind pushed the RP-1 fumes toward the rocket body
7. Downdraft near the rocket body made part of the fuel vapors sink downwards until diluted enough, so that this mixture won't catch fire anymore.
8. As of the point of ignition, I would point my finger towards electrical connections box up there, where either short or something else could have given the initial energy
After ignition:
1. Pressure ruptured both tanks, but first to arrive in scene was LOX, as the shockwave hit this tank first
2. Pressure wave pushed condensate cloud past the rocket (hence the whitish cloud is visible on left side, but barely visible on right side.
3. Arriving cold LOX should have suffocated the initial explosion if the strongback's structure would not have been wetted. Thus, it kept burning.
4. ...
Sure, but the proposal I was responding to was that there was an open vent on the RP1 tank that would allow a cloud of RP1 driven by evaporating leaked LOX to form outside the stage. The pressure relief valve wouldn't normally be open I don't believe. Obviously the LOX valve is open a lot during LOX loading to keep the pressure in the LOX tank under control due to boiling. There's nothing like that going on in the RP1 tank.I don't believe there is a vent for the RP1 that would be normally exhausting on the pad. The LOX vent is needed because the LOX is boiling during filling.
There is a pressure relief valve like the one on the LOX tank. RP-1 tank is pressurized with helium and safing procedures after test firings and stage landing obviously require the ability to vent that pressurant gas.
Hi, long time lurker here, but I have a question. I marked on the attached image a section of the second stage, near the Strongback. What is this for/what does it contain? I'm not sure if its structural or not, but it appears to connect down to the umbilical's at the base of the stage. There also in some older factory images appears to be some sort of wiring through there too. Does anyone know?
Sure, but the proposal I was responding to was that there was an open vent on the RP1 tank that would allow a cloud of RP1 driven by evaporating leaked LOX to form outside the stage. The pressure relief valve wouldn't normally be open I don't believe. Obviously the LOX valve is open a lot during LOX loading to keep the pressure in the LOX tank under control due to boiling. There's nothing like that going on in the RP1 tank.I don't believe there is a vent for the RP1 that would be normally exhausting on the pad. The LOX vent is needed because the LOX is boiling during filling.
There is a pressure relief valve like the one on the LOX tank. RP-1 tank is pressurized with helium and safing procedures after test firings and stage landing obviously require the ability to vent that pressurant gas.
The fireball happened during fueling. If fuel gets in, the gas in the tank (Nitrogen??) has to get out. This would imply an open vent, I think.Actually, it happened after fuel loading had completed and LOX loading had started but not finished.
I've watched this video and the frames #0 - #3 also countless times so, that they've been burned to my retina already. I've convinced myself, that the initial blast originated in strongback. Not inside rocket, not on rocket body skin. Look at the attached image for approx location of initial bang. Here's why I think so:One serious problem with this scenario is that RP1 vapor at anywhere near room temperature won't ignite and certainly won't explode even with an open flame. It's not at all like gasoline.
1. Reflection on rocket body below is larger than above. There's at least is some reflection on payload fairing.
2. Those "claws" in left (frame #1) are streams of condensate, that scatter light. The same thing was possibly visible from the other side.
3. Also big part of the "flash" below is actually reflection from rocket body combined with condensate scattering
4. If the blast would have originated on rocket skin, we should not have seen those "claws". Also hints on the destruction of the S2 skin should have been visible
My take on what happened.
1. On umbilical connection with RP-1 main line, a pinhole leak developed
2. As the RP-1 is at least under pressure to reach the top of the tank (and then some to get realistic flowspeeds), then the jet should have reached at least the altitude of LOX tank on S2, giving us nice fountain, whose tip was directed towards leftmost corner of strongback near the rocket
3. The rocket is about 35pixels wide on the video. Thus, the stream to be visible, it should have had the width of at least half of a pixel (meaning approximately 2 in). In addition, the stream was hidden by the frame of the strongback
4. The stream wetted the strongback frame and the walkway (now standing vertical)
5. Heat transfer from surrounding air, strongback frame and walkway took subcooled RP-1 back to vaporization temperatures
6. Warm wind pushed the RP-1 fumes toward the rocket body
7. Downdraft near the rocket body made part of the fuel vapors sink downwards until diluted enough, so that this mixture won't catch fire anymore.
8. As of the point of ignition, I would point my finger towards electrical connections box up there, where either short or something else could have given the initial energy
After ignition:
1. Pressure ruptured both tanks, but first to arrive in scene was LOX, as the shockwave hit this tank first
2. Pressure wave pushed condensate cloud past the rocket (hence the whitish cloud is visible on left side, but barely visible on right side.
3. Arriving cold LOX should have suffocated the initial explosion if the strongback's structure would not have been wetted. Thus, it kept burning.
4. ...
From P.B. de Selding:QuoteSpaceX President Shotwell: We anticipate return to flight in November, meaning down for three months. Next flight from CCAFS, then to VAFB.
https://twitter.com/pbdes/status/775702299402526720
That is a fast return and would indicate they have an idea what caused it or have narrowed it to not be the vehicle?
Question on the subject of possible COPV failure:The pictures I've seen of COPV failures look more or less like this:
Suppose a bottle failed and being mounted to the wall of the tank you got LOX and COPV material flying out. It has been posted up thread several times that COPV material itself will burn nicely with LOX, and perhaps even supply an ignition source just by force of the rupture.
Question: Is it reasonable to assume that the failed COPV bottle by itself without any RP-1 would supply enough fuel to create a blast of the size seen in the initial frame(s)? (perhaps it depends on how the bottle breaks apart, does it break into a few large pieces? or is it instantly turned into a large mass of tiny particles?)
From update threadThey figured it out and it's an easy fix?From P.B. de Selding:QuoteSpaceX President Shotwell: We anticipate return to flight in November, meaning down for three months. Next flight from CCAFS, then to VAFB.
https://twitter.com/pbdes/status/775702299402526720
That is a fast return and would indicate they have an idea what caused it or have narrowed it to not be the vehicle?
How do they go from 'we have no idea' to 'rtf in 3 months' in just a few days?
Question on the subject of possible COPV failure:
Suppose a bottle failed and being mounted to the wall of the tank you got LOX and COPV material flying out. It has been posted up thread several times that COPV material itself will burn nicely with LOX, and perhaps even supply an ignition source just by force of the rupture.
Question: Is it reasonable to assume that the failed COPV bottle by itself without any RP-1 would supply enough fuel to create a blast of the size seen in the initial frame(s)? (perhaps it depends on how the bottle breaks apart, does it break into a few large pieces? or is it instantly turned into a large mass of tiny particles?)
Followup: I think there's good evidence that it was interlaced, but that the interlacing has been filtered out. See this:
https://c7.staticflickr.com/9/8324/29619459086_d5c8623e19_z.jpg
(https://c7.staticflickr.com/9/8324/29619459086_d5c8623e19_z.jpg)
That's from the highest res video I could download from Youtube, 1080p mp4. Odd lines on the top, even lines on the bottom, split with:
ffmpeg -ss 71 -i video.mp4 -t 1 -vf il=d out-%04d.png
Note that halfway through the odd lines there suddenly starts a chromatic abberation, which slowly diminishes as it continues downward. The abberation continues along the even frames, top to bottom. Yet the "image" in both the even and odd rows is identical. It seems quite likely that the video was initially interlaced but has subsequently been deinterlaced during processing. If so then there would be an additional recoverable frame as well as highly precise (sub-millisecond) timing on when the explosion began and at least the X coordinate in the frame of the ignition point.
If the original wasn't interlaced, I'd expect that the images from the even and odd rows would look almost identical. They don't. I can't think of a way that this result could be explained by compression artifacts, either.
Followup: I think there's good evidence that it was interlaced, but that the interlacing has been filtered out. See this:
https://c7.staticflickr.com/9/8324/29619459086_d5c8623e19_z.jpg
(https://c7.staticflickr.com/9/8324/29619459086_d5c8623e19_z.jpg)
That's from the highest res video I could download from Youtube, 1080p mp4. Odd lines on the top, even lines on the bottom, split with:
ffmpeg -ss 71 -i video.mp4 -t 1 -vf il=d out-%04d.png
Note that halfway through the odd lines there suddenly starts a chromatic abberation, which slowly diminishes as it continues downward. The abberation continues along the even frames, top to bottom. Yet the "image" in both the even and odd rows is identical. It seems quite likely that the video was initially interlaced but has subsequently been deinterlaced during processing. If so then there would be an additional recoverable frame as well as highly precise (sub-millisecond) timing on when the explosion began and at least the X coordinate in the frame of the ignition point.
If the original wasn't interlaced, I'd expect that the images from the even and odd rows would look almost identical. They don't. I can't think of a way that this result could be explained by compression artifacts, either.
Someone earlier suggested that the 1080 was upsampled from the original of 720. That might do it.
Do you see the same on the 720 version?
Question on the subject of possible COPV failure:
Suppose a bottle failed and being mounted to the wall of the tank you got LOX and COPV material flying out. It has been posted up thread several times that COPV material itself will burn nicely with LOX, and perhaps even supply an ignition source just by force of the rupture.
Question: Is it reasonable to assume that the failed COPV bottle by itself without any RP-1 would supply enough fuel to create a blast of the size seen in the initial frame(s)? (perhaps it depends on how the bottle breaks apart, does it break into a few large pieces? or is it instantly turned into a large mass of tiny particles?)
Depends on the type and cause of failure, and how much energy is stored in the vessel at the time. High energy overpressure failures can turn the resin matrix into dust and expose the massive surface area of all the winding fibers very quickly.
Low pressure spot failures or puncture failures would simply vent the helium into the LOX tank relatively slowly and with little debris.
How sure are we explosion happened on TEL side of the rocket around common bulkhead? I looked at the video and traced trajectories of 3 fast moving objects visible in first few frames and they all seem to come out from interstage area.Interesting Marek, Could you post the link of which video you were watching and at what speed (normal?) you saw the objects...
From update threadThey figured it out and it's an easy fix?From P.B. de Selding:QuoteSpaceX President Shotwell: We anticipate return to flight in November, meaning down for three months. Next flight from CCAFS, then to VAFB.
https://twitter.com/pbdes/status/775702299402526720
That is a fast return and would indicate they have an idea what caused it or have narrowed it to not be the vehicle?
How do they go from 'we have no idea' to 'rtf in 3 months' in just a few days?
I put in a request at US Launch Report for the raw video, if they have it.
How do they go from 'we have no idea' to 'rtf in 3 months' in just a few days?
[OK, lets go with a hypothetical worst case, can anyone answer the question if that is enough fuel for the initial visible blast?I suspect we're well into flailing at a dead horse, but FWIW, I'm doubtful of an internal overpressure event such as a COPV failure simply because the initial flash was so fast and asymmetrical. There was no evidence of damage to the left side of the stage at the flash frame and no evidence of a wall failure before the flash frame. I'd expect an overpressure event to be more symmetrical and to first burst the wall, then ignite. If the ignition was inside the tank, I'd expect it to symmetrically blow out both sides.
(and for the record, considering they are now saying RTF in november, it's seems impossible for this to have been a COPV failure)
OK,In CRS-7 there wasn't a COPV failure, the COPV broke loose because of a strut failure and twisted and broke a helium line.
one serious flaw I see in all COPV scenarios is that COPV burst would clearly show on the telemetry.
In the CRS7 RUD, Elon tweeted about the sudden pressure drop in the first hours or so from the explosion.
So, as they are dealing with milliseconds of data, if the COPV would burst, they will see a pressure drop some milliseconds before the actual fire.. maybe also some other data I am not familiar with, but I am 99.99% sure, they would have known if it was that..
I would just forget about all the COPV speculations.. it would be too obvious for them to wonder about the reason for the RUD.
OK,In CRS-7 there wasn't a COPV failure, the COPV broke loose because of a strut failure and twisted and broke a helium line.
one serious flaw I see in all COPV scenarios is that COPV burst would clearly show on the telemetry.
In the CRS7 RUD, Elon tweeted about the sudden pressure drop in the first hours or so from the explosion.
So, as they are dealing with milliseconds of data, if the COPV would burst, they will see a pressure drop some milliseconds before the actual fire.. maybe also some other data I am not familiar with, but I am 99.99% sure, they would have known if it was that..
I would just forget about all the COPV speculations.. it would be too obvious for them to wonder about the reason for the RUD.
OK,
one serious flaw I see in all COPV scenarios is that COPV burst would clearly show on the telemetry.
In the CRS7 RUD, Elon tweeted about the sudden pressure drop in the first hours or so from the explosion.
So, as they are dealing with milliseconds of data, if the COPV would burst, they will see a pressure drop some milliseconds before the actual fire.. maybe also some other data I am not familiar with, but I am 99.99% sure, they would have known if it was that..
I would just forget about all the COPV speculations.. it would be too obvious for them to wonder about the reason for the RUD.
[OK, lets go with a hypothetical worst case, can anyone answer the question if that is enough fuel for the initial visible blast?I suspect we're well into flailing at a dead horse, but FWIW, I'm doubtful of an internal overpressure event such as a COPV failure simply because the initial flash was so fast and asymmetrical. There was no evidence of damage to the left side of the stage at the flash frame and no evidence of a wall failure before the flash frame. I'd expect an overpressure event to be more symmetrical and to first burst the wall, then ignite. If the ignition was inside the tank, I'd expect it to symmetrically blow out both sides.
(and for the record, considering they are now saying RTF in november, it's seems impossible for this to have been a COPV failure)
Just one tiny problem with Ms. Shotwell's tweet -- I doubt they'll be launching from CCAFS (SLC-40) any time soon. Much more likely from KSC (LC-39A), I would think... ;)
Just one tiny problem with Ms. Shotwell's tweet -- I doubt they'll be launching from CCAFS (SLC-40) any time soon. Much more likely from KSC (LC-39A), I would think... ;)
Shotwell didn't tweet anything. The tweet was secondhand from a statement.
Peter B. de Selding @pbdes 4m4 minutes ago
SpaceX's Shotwell: Nov return to flight is our best hope. We still haven't isolated the cause or whether its origin was rocket or ground.
Well, it appears the horse is alive after all, resume the beating. ::)QuotePeter B. de Selding @pbdes 4m4 minutes ago
SpaceX's Shotwell: Nov return to flight is our best hope. We still haven't isolated the cause or whether its origin was rocket or ground.
From P.B. de Selding:QuoteSpaceX President Shotwell: We anticipate return to flight in November, meaning down for three months. Next flight from CCAFS, then to VAFB.
https://twitter.com/pbdes/status/775702299402526720
That is a fast return and would indicate they have an idea what caused it or have narrowed it to not be the vehicle?
I wonder....https://twitter.com/pbdes
Dragon 39A.
Iridium - Vandy.
SES - 39A or LC-40.
FH - 39A?
(Oh and there's SHERPA somewhere in the mix).
Probably the subject of a new thread at some point.
Side to side movement. Never said anything about vertical. I would expect somebody on this forum to know that there is need to allow for vertical movement due to cryogenic contraction.
Don't know if Selding is interviewing Shotwell or how he is getting his info as his tweets keep coming in sporadically:
AMOS6:
LOX tank half full, neither tank pressurized. Yet sudden big fireball around LOX tank? Thats so unlikely, even if any of the tanks had sprouted a leak it would more likely have created a waterfall style outpour. Since the lox is subcooled it wouldnt even turn gaseous on exit like pressurized boiling lox, it would just pour.
I think that alone points at an external event.
How does that preclude something internal like a COPV explosion, which are mounted near the tank walls and in the vicinity of the common bulkhead?
But that's a mute point by now. Recent twitter information (return to flight in 3 month time, hinted on external cause, no change to F9 insurance rates, ...) is highly counter indicative to a failed COPV.
Side to side movement. Never said anything about vertical. I would expect somebody on this forum to know that there is need to allow for vertical movement due to cryogenic contraction.
I knew that! Asked about it twice. How exactly is the vertical shrinkage of the vehicle handled by the strongback?
Add a few RP-1 vapor sensors.
Have a few blind hunches. Strengthen this strut, improve that insulation. Add a few RP-1 vapor sensors. Put more cameras around the pad, make sure they and their data would survive a similar accident. And back to work.
Add a few RP-1 vapor sensors.
No such things
Add a few RP-1 vapor sensors.
No such things
Add a few RP-1 vapor sensors.
No such things
Maybe not stock on the shelf currently, but they should be easy to build.
This is the type of factual information that helps reduce idle speculation, so thank you. But it gives rise to other what-ifs.
1. It did sit there. It was 8 seconds from the beginning of the explosion until the appearance of the fairing tipping over.
2. The movement is the vehicle shrinking. So the vehicle is sliding against the pads in the gripper and cradle. The cradle pivot is not involved. The cradle is for when the vehicle is horizontal. Earlier strongback versions only had the gripper pads and the vehicle could not support the payload and fairing for long periods of time without supplemental support (crane and sling) while horizontal.
For instance, (not claiming this is true) what if a paint imperfection had extra thickness just above the lower support? Might be warm enough to melt the accumulating frost then refreezing as ice. THEN the paint/ice dam breaks allowing very rapid dropping of the stage and going from a locally tensile condition to local compression? Might have even been strong enough to scrape the paint just above, exposing bare aluminum.
But that's a mute point by now. Recent twitter information (return to flight in 3 month time, hinted on external cause, no change to F9 insurance rates, ...) is highly counter indicative to a failed COPV.
No, the 3 months is a hope and there is no hint
Which says a lot about how stage 2 unzipped, I think, which implies a rupture point at, or more likely just above, the common bulkhead...
Right where the lower support pads would be if the rocket had started to shrink down as the LOX was loaded. If the slide was unimpaired ...
Add a few RP-1 vapor sensors.
No such things
Maybe not stock on the shelf currently, but they should be easy to build.
Nonsense. No to everything on that list. Nice knee jerk reaction.What Jim said is the thing, most accidents by far happen in flight.
a. better served by putting sensors on the vehicle
b. Just need cameras with higher frame rate. The multi spectra is a waste and not going to provide more data. Just going to show what is already known.
b. seismographic, pressure, and sound recording instruments are a waste. Accidents happen in mostly in flight
c. EDS doesn't do anything for accident reduction. It uses existing sensors.
Add a few RP-1 vapor sensors.
No such things
Maybe not stock on the shelf currently, but they should be easy to build.
What???? Sure there are.
See http://s7d9.scene7.com/is/content/minesafetyappliances/General%20Monitors%20Product%20Catalog-1
just for some of the many many flammable vapor detectors
Don't know if Selding is interviewing Shotwell or how he is getting his info as his tweets keep coming in sporadically:
Peter B. de Selding @pbdes 3 minutes ago
SpaceX's Shotwell: Falcon Heavy wont launch this year, likely Q1 next year. Could be from Pad 39A or from VAFB, not sure.
Peter B. de Selding @pbdes 23 minutes ago
Shotwell: Not 100% certain if we'll launch from VAFB or CCAFS for next flight. Depends on customer. Both pads will be ready.
Peter B. de Selding @pbdes 26 minutes ago
Shotwell: Will 'probably not' put payloads on next few static fires, but too easy to say, given Sept 1, that doing so is always bad idea.
Peter B. de Selding @pbdes 27 minutes ago
SpaceX's Shotwell: Nov return to flight is our best hope. We still haven't isolated the cause or whether its origin was rocket or ground.
Peter B. de Selding @pbdes 1 hour ago
SpaceX's Shotwell: We have been told that the Sept. 1 anomaly will not affect Falcon 9's insurance rates. So we expect no impact.
Peter B. de Selding @pbdes 1 hour ago
SpaceX President Shotwell: We anticipate return to flight in November, meaning down for three months. Next flight from CCAFS, then to VAFB.
Sounds like they know which component went pop, but don't know why.....and possibly don't care why. If they are having continuous confidence issues with the criminal component, maybe they are just going to replace it with something completely different, therefore there is no need for a long drawn out investigation.
..., most accidents by far happen in flight.
These measures are in place to capture the rare events, aka failures...
By your logic, most flights happen without an incident, so why use such sensors at all?
If sensors were there only to measure mission success, nobody would be worried about getting the data out within a milliSec....
If sensors were there only to measure mission success, nobody would be worried about getting the data out within a milliSec....
The point is, failures happen, and are rare, and discounting ideas about sensors just because "failure is not expected there" is misguided.
Nobody ever expects the Spanish inquisition.
RP-1 sensor? No vapors are not explosive. Aerosol monitor, there is no such thing. Anyways, use a camera to look for leaks.
Add a few RP-1 vapor sensors.
No such things
Maybe not stock on the shelf currently, but they should be easy to build.
What???? Sure there are.
See http://s7d9.scene7.com/is/content/minesafetyappliances/General%20Monitors%20Product%20Catalog-1
just for some of the many many flammable vapor detectors
RP-1 specifically and not just hydrocarbon.
And the actual point is that it is not needed with RP-1. The fumes are not explosive.
Using the flare as a crosshair I get a point of origin just outside of the rocket, just above the strongback attachment.From the picture in this post, there is a plastic support from the strongback that pushes against the rocket at just about the common bulkhead. Suppose LOX does liquify from the air here (Jim thinks this unlikely, but the literature is full of references for this happening with LN2, and this is colder) Also this looks like right at the bottom of the LOX tank, so it would be cold early in the fill sequence, and high enough so the LOX would not need to run over any warmer portions (and hence evaporate) before hitting the plastic bumper.
Hmm, let’s see the compatibility of various kind of rubber with oxygen:Lots of stuff that is perfectly compatible with GOX is a hazard with LOX. So if SpaceX was not expecting LOX here, the combination could be explosive.
How much? Assuming the stage one LOX tank is 30m tall, cools by 240K (306K->66K), coefficient of thermal expansion 22 microns/meter/K, we get a contraction of 15 cm. So this point would be expected to be sliding at this point in the count, as the first stage tank fills.The vehicle just slides in it.Side to side movement. Never said anything about vertical. I would expect somebody on this forum to know that there is need to allow for vertical movement due to cryogenic contraction.I knew that! Asked about it twice. How exactly is the vertical shrinkage of the vehicle handled by the strongback?
If sensors were there only to measure mission success, nobody would be worried about getting the data out within a milliSec....
The point is, failures happen, and are rare, and discounting ideas about sensors just because "failure is not expected there" is misguided.
Nobody ever expects the Spanish inquisition.
If your sensor fails or is suspected of failure, it is the Spanish Inquisition according to NASA. I have personal knowledge.
The multi spectra is a waste and not going to provide more data. Just going to show what is already known.
From wiki:
RP-1 sensor? No vapors are not explosive. Aerosol monitor, there is no such thing. Anyways, use a camera to look for leaks.
Im not sure if you are saying the absence of vapors is not explosive (true) or that kerosene vapors are not explosive (false). The explosive range of kerosene vapors is .7%-5% volume of air (a relatively narrow range as far as they go) and easily detectable by a sub $1000 air monitor.
Because of the lack of light hydrocarbons, RP-1 has a high flash point, and is less of a fire hazard than gasoline/petrol or even some jet and diesel fuels.
I don't know about you, but I would not be enthusiastic about forcefully sliding a large chunk of LOX-soaked plastic across a surface while pressing on it.
Lets list all the assumptions not backed by data
I don't know about you, but I would not be enthusiastic about forcefully sliding a large chunk of LOX-soaked plastic across a surface while pressing on it.
The multi spectra is a waste and not going to provide more data. Just going to show what is already known.
How do you know this in all cases?
Also this looks like right at the bottom of the LOX tank, so it would be cold early in the fill sequence, and high enough so the LOX would not need to run over any warmer portions (and hence evaporate) before hitting the plastic bumper.
Personally, I'm not convinced at all that the explosion started on the side of the vehicle the camera was viewing. It certainly flashed to the camera side, but it could well have started on the other side and blew around the stage.The initial frame shows nothing, then the one after that shows a fireball that has expanded at nearly the speed of sound.
Personally, I'm not convinced at all that the explosion started on the side of the vehicle the camera was viewing. It certainly flashed to the camera side, but it could well have started on the other side and blew around the stage.The initial frame shows nothing, then the one after that shows a fireball that has expanded at nearly the speed of sound.
For it to have started at the back, and moved all the way round to completely encircle the front, would have taken it considerably supersonic, and caused a rather more energetic explosion. Some of the ligthning rods would also be differently illuminated.
But not nescessarily the distribution of the elements involved in an incident like this.
I applied Luma, Alpha, and Hue filters to the video and found two areas on the TEL that show change in their values. The top area is the payload A/C. The Luma /Alpha channels show activity throughout the video until 133 ms before the initial flash. At that time all Luma/Alpha activity concentrates in one small area.
The lower area is centered in the area of the initial flash. The Luma/Alpha activity in this area is intermittent. Under some filter combinations I get the impression of something escaping or flowing from one of the ducts. This could be a false artifact from the interplay of filters and video compression.
Something new to think about.
The quick RTFS could be the result of new evidence from the examination of the TEL.
Sounds like they know which component went pop, but don't know why.....and possibly don't care why. If they are having continuous confidence issues with the criminal component, maybe they are just going to replace it with something completely different, therefore there is no need for a long drawn out investigation.
No, she said they didn't know and the 3 months is a hope
My guess: the umbilical moved slightly.
That would account for a "large" image change, and would be expected with wind/completion of RP-1 loading/initiation of LOX loading/etc.
Well, the area in red is the top of stage 1, at the very bottom of the interstage, from what I can tell.
What goes into the rocket, or interfaces between the TEL and the rocket, right there? I doubt there is any fueling happening that high up on stage 1, so perhaps this is where the AC umbilical connects to the interstage? I know per several things that have been posted throughout this thread that the AC system ventilates and purges both the payload fairing and the interstage. Maybe this is where the AC umbilicals go into the interstage?
The LOX and RP-1 feed lines for stage 2 should be running right behind this area, though -- they reach up to the base of stage 2.
Well, the area in red is the top of stage 1, at the very bottom of the interstage, from what I can tell.
What goes into the rocket, or interfaces between the TEL and the rocket, right there? I doubt there is any fueling happening that high up on stage 1, so perhaps this is where the AC umbilical connects to the interstage? I know per several things that have been posted throughout this thread that the AC system ventilates and purges both the payload fairing and the interstage. Maybe this is where the AC umbilicals go into the interstage?
The LOX and RP-1 feed lines for stage 2 should be running right behind this area, though -- they reach up to the base of stage 2.
For sure there is the AC connection to the interstage there. Jim can correct me if I am wrong, but I thought RP1 was loaded in the umbilical below the Lox (there at the interstage with the AC).
I believe there are 5 total umbilical lines[interstage through Stage2] (At least from the SES-9 launch) 1xRP1, 1xHe, 1xAC, 1XLox,1x(? power/data?) Not certain what ones are below through
Would there be an expected venting of any kind to the right of that area, keeping in mind the wind is blowing right to left? Is there anything that could vent to the right of that area, unexpectedly?
- - - -
Please comment on my comment just before your comment. :) Please. :)
Well, the area in red is the top of stage 1, at the very bottom of the interstage, from what I can tell.
What goes into the rocket, or interfaces between the TEL and the rocket, right there? I doubt there is any fueling happening that high up on stage 1, so perhaps this is where the AC umbilical connects to the interstage? I know per several things that have been posted throughout this thread that the AC system ventilates and purges both the payload fairing and the interstage. Maybe this is where the AC umbilicals go into the interstage?
The LOX and RP-1 feed lines for stage 2 should be running right behind this area, though -- they reach up to the base of stage 2.
For sure there is the AC connection to the interstage there. Jim can correct me if I am wrong, but I thought RP1 was loaded in the umbilical below the Lox (there at the interstage with the AC).
I believe there are 5 total umbilical lines[interstage through Stage2] (At least from the SES-9 launch) 1xRP1, 1xHe, 1xAC, 1XLox,1x(? power/data?) Not certain what ones are below through
repeating a question I asked of another comment:
Possible, but after I posted the image, I looked at our video stream.
Remember, it could be changes in luminance rather than a physical event. The red area is extremely precise. It not like +- x%. That's exactly where the change occurs.
My irrefutable rock solid no one can doubt me interpretation is a bit different.
In the video stream, that region appears to grow light & dark over time. It's consistent in behavior with the obvious venting seen to the left of the F9.
It could be the result of something venting a semi-opaque cloud to the right (above right, below right, unknown right). The region appears to be between the F9 and the TE. There should be no reason for there to be a change in luminosity, unless something is changing the luminosity. The video doesn't show a physical motion as best as I can tell, i.e. a change in the physical structure of F9 and TE. It does show luminosity changes.
Would there be an expected venting of any kind to the right of that area, keeping in mind the wind is blowing right to left? Is there anything that could vent to the right of that area, unexpectedly?
"Pressing" and "Forcefully sliding" - until the clamps let go, they are surely pressing on the far side of the rocket. No way they would have an air gap and let the rocket rattle back and forth against the clamps - that would confuse the telemetry if nothing else. So until the arms are opened, the rocket will be pressed into the pad on the erector. And thermal contraction generates big forces, so it will slide despite being pushed against the rocket.I don't know about you, but I would not be enthusiastic about forcefully sliding a large chunk of LOX-soaked plastic across a surface while pressing on it.Lets list all the assumptions not backed by data
Forcefully sliding
Pressing
LOX
soaked
plastic
Systems including liquid nitrogen traps must never be opened to the atmosphere until the trap is removed from the coolant. Oxygen has a higher boiling point (-183 ƒC) than nitrogen (-196 ƒC), and will condense out of the atmosphere and collect in a liquid-nitrogen cooled vessel open to the air. Liquid oxygen forms highly explosive mixtures with many organic materials.or here (https://www.ucd.ie/t4cms/UCD%20Liquid%20Nitrogen%20Safety%20Guide.pdf) (bold mine)
In some scenarios it is possible for containers holding liquid nitrogen to become sufficiently cooled so that the oxygen in the atmosphere condenses and forms liquid oxygen on the cooled surfaces. This can occur when vessels that are open to the atmosphere are cooled on the outside by liquid nitrogen thus allowing liquid oxygen to form on the inside of the vessel. Similarly pipe work cooled internally by liquid nitrogen can allow liquid oxygen to condense on the outside.Note that in particular, the tendency of these surfaces to form frost does not always suppress the formation of LOX.
So my standard daily question. Exactly what is at the area identified in red? It changed, whatever is there, more than any other changes (factor of 5) in the frame comparison. In the last 20 odd seconds prior to the event, would a change be expected where indicated?
So my standard daily question. Exactly what is at the area identified in red? It changed, whatever is there, more than any other changes (factor of 5) in the frame comparison. In the last 20 odd seconds prior to the event, would a change be expected where indicated?
If you go back to the original USLR video, you will see that the area identified is often completely obscured by dark venting. When not obscured, it is a bright area, so perhaps it should not be surprising that it changes more than any other area?
I have attached the SES-9 photo so you might look to see anything I missed.
However, yeah -- thinking about it again and staring at the picture again, I think I was dead wrong. The red spot is up near the top of the interstage, seeing as how it's just above the level of the grid fins. And that would not only be where the AC vent goes in, but also where the LOX and RP-1 feeds go in.
So, yeah, the red spot would seem to be right around where he propellants were being loaded. That could be significant.
Helium pressure for pneumatic sep Herb...I have attached the SES-9 photo so you might look to see anything I missed.
That photo reminds me of one other thing in that general vicinity: the stage separation latches - SpaceX doesn't like to use pyros and those are pneumatic, as I recall. I don't know details of how they are pressurized and actuated, however.
.Helium pressure for pneumaic sep Herb...I have attached the SES-9 photo so you might look to see anything I missed.
That photo reminds me of one other thing in that general vicinity: the stage separation latches - SpaceX doesn't like to use pyros and those are pneumatic, as I recall. I don't know details of how they are pressurized and actuated, however.
nice, but in this image sequence, it is not obscured.
Basically, we've composited 11 seconds worth of frames into one frame, skipped about 9 seconds, and composited the last second into one frame, and then looked at any significant differences. (Don't do this at home without adult supervision)
<snip>
Will the outside of the rocket be less than 77K? Yes, if the inside is at 66K. The thermal conductivity of aluminum is about 205 w/m/k. So to get an 11K drop across a 5 mm thickness you would need a heat flow of 205*11/0.005 = 451 kw/m^2. No way you have that from condensing air, so the outside temp is less than 77K.
<snip>
Difference analysis pass # 1.First off, I want to thank glennfish for all of this hard work in working with the very limited resources available to us.
This is an analysis comparing the first 11 seconds composite image content with the last second image composite content. Technique explained previously in this thread.
The idea is: Something changing over a long period of time, resulted in what seemed to happen in 16 milliseconds, and might be visible in the corrected image streams we have provided.
Interestingly, there is only one, I repeat one, dramatic change occurring in this initial (of many) image processing test.
Basically, we've composited 11 seconds worth of frames into one frame, skipped about 9 seconds, and composited the last second into one frame, and then looked at any significant differences. (Don't do this at home without adult supervision)
The differences could be physical, luminosity, etc... the why list is prior in this thread as to possible causes, except causes 4 & 5 are extremely unlikely at this level of processing.
The one difference in this comparison (and there will be more comparisons) is red on the attached image.
So my standard daily question. Exactly what is at the area identified in red? It changed, whatever is there, more than any other changes (factor of 5) in the frame comparison. In the last 20 odd seconds prior to the event, would a change be expected where indicated?
This is not a diagnosis of failure or causes, it's a question initiated by a imaging change analysis process. Your answers may help refine the process.
Helium to release the latches and Helium pneumatic pushers for assured stage separation...Difference analysis pass # 1.First off, I want to thank glennfish for all of this hard work in working with the very limited resources available to us.
This is an analysis comparing the first 11 seconds composite image content with the last second image composite content. Technique explained previously in this thread.
The idea is: Something changing over a long period of time, resulted in what seemed to happen in 16 milliseconds, and might be visible in the corrected image streams we have provided.
Interestingly, there is only one, I repeat one, dramatic change occurring in this initial (of many) image processing test.
Basically, we've composited 11 seconds worth of frames into one frame, skipped about 9 seconds, and composited the last second into one frame, and then looked at any significant differences. (Don't do this at home without adult supervision)
The differences could be physical, luminosity, etc... the why list is prior in this thread as to possible causes, except causes 4 & 5 are extremely unlikely at this level of processing.
The one difference in this comparison (and there will be more comparisons) is red on the attached image.
So my standard daily question. Exactly what is at the area identified in red? It changed, whatever is there, more than any other changes (factor of 5) in the frame comparison. In the last 20 odd seconds prior to the event, would a change be expected where indicated?
This is not a diagnosis of failure or causes, it's a question initiated by a imaging change analysis process. Your answers may help refine the process.
Your red spot appears to be on the perimeter at the top of the interstage. One thing found in this area is the connection mechanism to the second stage. There are several attach points that are either explosively or pneumatically actuated in conjunction with the pusher mechanism. I know Elon is not a fan of the pyrotechnic release, but not 100% sure what it utilized here. Possible source of ignition?
Your red spot appears to be on the perimeter at the top of the interstage. One thing found in this area is the connection mechanism to the second stage. There are several attach points that are either explosively or pneumatically actuated in conjunction with the pusher mechanism. I know Elon is not a fan of the pyrotechnic release, but not 100% sure what it utilized here. Possible source of ignition?
Dang - sorry Herb. The issue is I read a thread, see something I want to comment on, quote it, reply and it gets dumped at the end of thread - skipping over the intervening posts. I try to skim forward to end of thread first, but man does this particular thread grow fastYour red spot appears to be on the perimeter at the top of the interstage. One thing found in this area is the connection mechanism to the second stage. There are several attach points that are either explosively or pneumatically actuated in conjunction with the pusher mechanism. I know Elon is not a fan of the pyrotechnic release, but not 100% sure what it utilized here. Possible source of ignition?
Man, nobody reads the thread, even a few posts back. ;)
https://forum.nasaspaceflight.com/index.php?topic=30981.msg1583462#msg1583462
.Helium pressure for pneumaic sep Herb...I have attached the SES-9 photo so you might look to see anything I missed.
That photo reminds me of one other thing in that general vicinity: the stage separation latches - SpaceX doesn't like to use pyros and those are pneumatic, as I recall. I don't know details of how they are pressurized and actuated, however.
Ah, more pressurized helium, then. Figured it would be that or N2. It probably makes sense that the latches themselves use the same fluid. I wonder if ther might've been a failure in that system that affected the umbilicals nearby. Perhaps that might account for the sounds Elon's tweet referred to. Totally spitballing here, but if Glennfish's video analysis "red dot" is a real thing, it's another system in the general vicinity to think about a bit.
First off, I want to thank glennfish for all of this hard work in working with the very limited resources available to us.
Your red spot appears to be on the perimeter at the top of the interstage. One thing found in this area is the connection mechanism to the second stage. There are several attach points that are either explosively or pneumatically actuated in conjunction with the pusher mechanism. I know Elon is not a fan of the pyrotechnic release, but not 100% sure what it utilized here. Possible source of ignition?
My guess: the umbilical moved slightly.
That would account for a "large" image change, and would be expected with wind/completion of RP-1 loading/initiation of LOX loading/etc.
Possible, but after I posted the image, I looked at our video stream.
Remember, it could be changes in luminance rather than a physical event. The red area is extremely precise. It not like +- x%. That's exactly where the change occurs.
My irrefutable rock solid no one can doubt me interpretation is a bit different.
In the video stream, that region appears to grow light & dark over time. It's consistent in behavior with the obvious venting seen to the left of the F9.
It could be the result of something venting a semi-opaque cloud to the right (above right, below right, unknown right). The region appears to be between the F9 and the TE. There should be no reason for there to be a change in luminosity, unless something is changing the luminosity. The video doesn't show a physical motion as best as I can tell, i.e. a change in the physical structure of F9 and TE. It does show luminosity changes.
Would there be an expected venting of any kind to the right of that area, keeping in mind the wind is blowing right to left? Is there anything that could vent to the right of that area, unexpectedly?
Good point. I ignored the paint since it's very thin, but it turns out that's a bad guess. Assuming the paint is 0.1mm thick (since they don't want any extra mass), then it's 50x thinner than the aluminum. But at least generic paint is a rotten thermal conductor - this report (http://www.thefreelibrary.com/Special+heat+capacity+and+thermal+conductivity.-a0228354685) claims 0.17 w/m/K, or about 1000x worse than aluminum. So even if it's only 1/50th as thick, it's still a 20x better insulator than the aluminum. However, this would still need a flux of 20 kw/m^2 to maintain a delta-T of 11 degrees. This online heat transfer calculator (http://www.efunda.com/formulae/heat_transfer/convection_forced/calc_lamflow_isothermalplate.cfm#calc) estimates heat transfer from a 70K plate in a 4 m/s wind to be about 2kw/m^2, so the surface will still be much closer to 66K than 77K.<snip>
Will the outside of the rocket be less than 77K? Yes, if the inside is at 66K. The thermal conductivity of aluminum is about 205 w/m/k. So to get an 11K drop across a 5 mm thickness you would need a heat flow of 205*11/0.005 = 451 kw/m^2. No way you have that from condensing air, so the outside temp is less than 77K.
<snip>
Surely this calculation would only apply if the outside of the rocket were unpainted Al? But we know it's painted, and upthread I admitted complete ignorance about what kind of paint, and how thick (and how potentially explosive in contact with LOX ...). Does anyone here know these details?
My guess: the umbilical moved slightly.
That would account for a "large" image change, and would be expected with wind/completion of RP-1 loading/initiation of LOX loading/etc.
Possible, but after I posted the image, I looked at our video stream.
Remember, it could be changes in luminance rather than a physical event. The red area is extremely precise. It not like +- x%. That's exactly where the change occurs.
My irrefutable rock solid no one can doubt me interpretation is a bit different.
In the video stream, that region appears to grow light & dark over time. It's consistent in behavior with the obvious venting seen to the left of the F9.
It could be the result of something venting a semi-opaque cloud to the right (above right, below right, unknown right). The region appears to be between the F9 and the TE. There should be no reason for there to be a change in luminosity, unless something is changing the luminosity. The video doesn't show a physical motion as best as I can tell, i.e. a change in the physical structure of F9 and TE. It does show luminosity changes.
Would there be an expected venting of any kind to the right of that area, keeping in mind the wind is blowing right to left? Is there anything that could vent to the right of that area, unexpectedly?
Might I suggest trying to establish a sort-of "control" measurement by running a similar "Difference Analysis" on other sets of frames? This might provide a sanity check and indicate whether or not that red dot is truly indicative of something anomalous.
What if you take the 11 second composite and compare it with a 1 second composite 10 seconds back or 20 seconds back? Or better yet, does USLaunchReport have similar footage of previous launches or static test fires from the same vantage point and camera setup? Maybe you could run a similar analysis on those at the same point in the countdown sequence and see whether or not you can produce similar results (red dot in that same location)?
If you can produce similar results in other video or frame intervals that didn't immediately precede the explosion, maybe you are just seeing the effect of something benign, such as an umbilical shifting in the wind. If you run these control measurements and it only produces this red dot at that location in this one instance at this particular time, and you can't produce something similar elsewhere, then that could be a strong indication that you are on to something real and significant.
The TE at pad 40 is the only one of the three that is not falcon heavy compatible.
How many other differences are there to the other two TEs?
Are the other 2 TEs identical?
If they are significantly different to the one at pad 40, and the problem is external to the vehicle, it could be good news for RTF.
The TE at pad 40 had the most launches, and had been modified several times for each version of the Falcon 9. Could that have contributed?
I applied Luma, Alpha, and Hue filters to the video and found two areas on the TEL that show change in their values. The top area is the payload A/C. The Luma /Alpha channels show activity throughout the video until 133 ms before the initial flash. At that time all Luma/Alpha activity concentrates in one small area.
The lower area is centered in the area of the initial flash. The Luma/Alpha activity in this area is intermittent. Under some filter combinations I get the impression of something escaping or flowing from one of the ducts. This could be a false artifact from the interplay of filters and video compression.
Something new to think about.
The quick RTFS could be the result of new evidence from the examination of the TEL.
What is a real world physics interpretation of Luma/Alpha activity? Is it turning green, bright? Did the AGC on the camera adjust to changing light levels?
The TE at pad 40 is the only one of the three that is not falcon heavy compatible.
How many other differences are there to the other two TEs?
Are the other 2 TEs identical?
If they are significantly different to the one at pad 40, and the problem is external to the vehicle, it could be good news for RTF.
The TE at pad 40 had the most launches, and had been modified several times for each version of the Falcon 9. Could that have contributed?
I applied Luma, Alpha, and Hue filters to the video and found two areas on the TEL that show change in their values. The top area is the payload A/C. The Luma /Alpha channels show activity throughout the video until 133 ms before the initial flash. At that time all Luma/Alpha activity concentrates in one small area.
The lower area is centered in the area of the initial flash. The Luma/Alpha activity in this area is intermittent. Under some filter combinations I get the impression of something escaping or flowing from one of the ducts. This could be a false artifact from the interplay of filters and video compression.
Something new to think about.
The quick RTFS could be the result of new evidence from the examination of the TEL.
What is a real world physics interpretation of Luma/Alpha activity? Is it turning green, bright? Did the AGC on the camera adjust to changing light levels?
There is a change in brightness on the Green and Red channels. I require more information on the USRL camera to know the color weighted algorithm used to determine Luma. The brightness changes are pixel specific. The AGC changes occur during the explosion.
Well if you look on the USLR video prior to the cut at 50 seconds it looks like there is at the very least a LOx vent in the area. I would highly doubt that they would vent anything else there (Except maybe He) I have attached the SES-9 photo so you might look to see anything I missed.
I applied Luma, Alpha, and Hue filters to the video and found two areas on the TEL that show change in their values. The top area is the payload A/C. The Luma /Alpha channels show activity throughout the video until 133 ms before the initial flash. At that time all Luma/Alpha activity concentrates in one small area.
The lower area is centered in the area of the initial flash. The Luma/Alpha activity in this area is intermittent. Under some filter combinations I get the impression of something escaping or flowing from one of the ducts. This could be a false artifact from the interplay of filters and video compression.
Something new to think about.
The quick RTFS could be the result of new evidence from the examination of the TEL.
What is a real world physics interpretation of Luma/Alpha activity? Is it turning green, bright? Did the AGC on the camera adjust to changing light levels?
There is a change in brightness on the Green and Red channels. I require more information on the USRL camera to know the color weighted algorithm used to determine Luma. The brightness changes are pixel specific. The AGC changes occur during the explosion.
The pixels will have gone through a fair amount of processing before they get saved - debayers (converting the bayer array of pixels to YUV), black level, denoise, AGC, AWB and a load of other stuff. Then it gets compressed. Pixel level changes could be noise, or introduced by denoise. I'd be very wary about using imagery after all that processing. If the raw bayer images were available, that would be a better source, although I suspect they won't be - the storage and bandwidth requirements for raw 4k video at 60fps are prohibitive, and unlikely to be used for a static fire.
.Helium pressure for pneumaic sep Herb...I have attached the SES-9 photo so you might look to see anything I missed.
That photo reminds me of one other thing in that general vicinity: the stage separation latches - SpaceX doesn't like to use pyros and those are pneumatic, as I recall. I don't know details of how they are pressurized and actuated, however.
Ah, more pressurized helium, then. Figured it would be that or N2. It probably makes sense that the latches themselves use the same fluid. I wonder if ther might've been a failure in that system that affected the umbilicals nearby. Perhaps that might account for the sounds Elon's tweet referred to. Totally spitballing here, but if Glennfish's video analysis "red dot" is a real thing, it's another system in the general vicinity to think about a bit.
please save me a half hour of searching this thread. At what points prior to Frame 0 did the sounds occur. I can look at before/after image groups to that point in time. If you want to same me more time, at 60 frames per second, with the last 3 frames in the database ignored from the download, which frame(s) in our data provided correspond to the clang and thunk. :)
1. The outside of the tank must be far enough below 90K to prevent condensing LOx from evaporating.
2. The condensation of oxygen must not have happened on the vastly longer first stage oxygen tanks during any of the horizontal test burns performed since SpaceX started working on subcooling LOx, such that no-one noticed the LOx dripping off and said "Hey do we have a LOx leak", and investigated the issue. Nor noticed on either stage in any previous vertical static-fire or launch.
3. Something must rub off the ice to expose the bare tank wall.
5. The thicker external skin of the ring around the common bulkhead must also be far enough below 90K for LOx to form faster than it evaporates.
8. Something something then causes the below-90K "plastic" to catch fire.
9. ...causing our initial explosion.
Just so I've got the LOx-from-air scenario clear...Technically, it's condensing faster than it's evaporating. This is know to happen with LN2 (see references). The outside is colder than LN2 (see calculations). So yes.
1. The outside of the tank must be far enough below 90K to prevent condensing LOx from evaporating.
2. The condensation of oxygen must not have happened on the vastly longer first stage oxygen tanks during any of the horizontal test burns performed since SpaceX started working on subcooling LOx, such that no-one noticed the LOx dripping off and said "Hey do we have a LOx leak", and investigated the issue. Nor noticed on either stage in any previous vertical static-fire or launch.I'm sure that when SpaceX people noticed liquid on the outside of a sub-cooled surface, then knew it was condensed air. It's in every cryo textbook and every university tract on dealing with cryo. It was a known pain when dealing with liquid hydrogen.
3. Something must rub off the ice to expose the bare tank wall. So...No, depends on the conditions. Sometimes you get frost, sometimes a combination, and sometimes the liquid air prevents the frost formation. See the references - they get LOX dripping off with no scraping of the ice required.
4. As the F9 shrinks due to the second stage LOx fill (but after shrinkage caused by the previous main stage LOx fill), the small support brace below the hydraulic/pneumatic grapples, resting against the reinforced area that rings of the common bulkhead, must slide enough to scrape ice off that aforementioned reinforced area that rings the common bulkhead.As per references, scraping not required, and the first stage LOX fill is not done until 2:40 before launch. So the first stage is still shrinking at T-8:00.
5. The thicker external skin of the ring around the common bulkhead must also be far enough below 90K for LOx to form faster than it evaporates.Yes. The thicker aluminum at this point makes almost no difference, as the thermal conductivity is dominated by the paint. See the calculations above.
6. The LOx forming on the newly exposed skin at the bottom of the common bulkhead ring must run... up?... to soak into the protective "plastic" pads of the support brace.No, the LOX tank wall is above the common bulkhead. If the "plastic" support thingy is located at the bulkhead, which makes mechanical sense and looks consistent with the picture, then LOX forming on the wall of the tank runs down onto the plastic support.
7. The protective "plastic" pads of the support brace, connected to the metal of the support brace, must also be far enough below 90K to prevent the soaking LOx from evaporating or just boiling away.The surface of the plastic brace is pushed against a (painted) aluminum surface at well under 77K. Plastic has a thermal conductivity orders of magnitude less than aluminum (epoxy, for example, is 0.35 w/m/K). The pad is visible on photos, so cannot be too thin. So a temperature gradient will form across the pad, with the rocket surface at close to 66K and the T/E surface at ambient. But the rocket facing surface, and the first few mm of pad, will surely be cold enough to prevent the LOX from evaporating.
8. Something something then causes the below-90K "plastic" to catch fire.LOX plus organics can be sensitive explosives. And this would be scraping across the surface as the first stage fill completes.
9. ...causing our initial explosion.Perhaps. Could enough LOX condense in the time available? What's the "plastic" made of? SpaceX must have known of the possibility of LOX condensing, what countermeasures did they take? We are all just guessing based on very limited data. But this would explain the no-show on telemetry, the location of the fault, and the difficulty of telling inside from outside cause.
Don't forget to account for the partial pressure of oxygen in the atmosphere. It's not pure oxygen at STP.Good point. I ignored the paint since it's very thin, but it turns out that's a bad guess. Assuming the paint is 0.1mm thick (since they don't want any extra mass), then it's 50x thinner than the aluminum. But at least generic paint is a rotten thermal conductor - this report (http://www.thefreelibrary.com/Special+heat+capacity+and+thermal+conductivity.-a0228354685) claims 0.17 w/m/K, or about 1000x worse than aluminum. So even if it's only 1/50th as thick, it's still a 20x better insulator than the aluminum. However, this would still need a flux of 20 kw/m^2 to maintain a delta-T of 11 degrees. This online heat transfer calculator (http://www.efunda.com/formulae/heat_transfer/convection_forced/calc_lamflow_isothermalplate.cfm#calc) estimates heat transfer from a 70K plate in a 4 m/s wind to be about 2kw/m^2, so the surface will still be much closer to 66K than 77K.<snip>
Will the outside of the rocket be less than 77K? Yes, if the inside is at 66K. The thermal conductivity of aluminum is about 205 w/m/k. So to get an 11K drop across a 5 mm thickness you would need a heat flow of 205*11/0.005 = 451 kw/m^2. No way you have that from condensing air, so the outside temp is less than 77K.
<snip>
Surely this calculation would only apply if the outside of the rocket were unpainted Al? But we know it's painted, and upthread I admitted complete ignorance about what kind of paint, and how thick (and how potentially explosive in contact with LOX ...). Does anyone here know these details?
I extracted snapshots of second stage from various SpaceX photos - these may be useful for you guys:
Here's the interstage area. You can see two vents on opposite sides half way up the interstage. These might be for venting GOX used to pre-chill the engine. Not sure if they are venting at T-8 minutes.
.Helium pressure for pneumaic sep Herb...I have attached the SES-9 photo so you might look to see anything I missed.
That photo reminds me of one other thing in that general vicinity: the stage separation latches - SpaceX doesn't like to use pyros and those are pneumatic, as I recall. I don't know details of how they are pressurized and actuated, however.
Ah, more pressurized helium, then. Figured it would be that or N2. It probably makes sense that the latches themselves use the same fluid. I wonder if ther might've been a failure in that system that affected the umbilicals nearby. Perhaps that might account for the sounds Elon's tweet referred to. Totally spitballing here, but if Glennfish's video analysis "red dot" is a real thing, it's another system in the general vicinity to think about a bit.
please save me a half hour of searching this thread. At what points prior to Frame 0 did the sounds occur. I can look at before/after image groups to that point in time. If you want to same me more time, at 60 frames per second, with the last 3 frames in the database ignored from the download, which frame(s) in our data provided correspond to the clang and thunk. :)
With regard to the sounds... We don't know for sure what sounds Elon was referring as there are several in the sound track from US Launch Alliance video, but IMHO there are two sounds of interest. That is assuming they are from the pad and not from some other direction completely. So far we don't have any information either way.
That said, assuming they are from the pad, then they occur at 1:06.5 and 1:07.5 in the video timeline.
(i.e. 1:18.64 and 1:19.64 video sound track).
Previous information on the sounds at:
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1581255#msg1581255 (http://forum.nasaspaceflight.com/index.php?topic=30981.msg1581255#msg1581255)
If you go back to the original USLR video, you will see that the area identified is often completely obscured by dark venting. When not obscured, it is a bright area, so perhaps it should not be surprising that it changes more than any other area?
Don't forget to account for the partial pressure of oxygen in the atmosphere. It's not pure oxygen at STP.Good point. I ignored the paint since it's very thin, but it turns out that's a bad guess. Assuming the paint is 0.1mm thick (since they don't want any extra mass), then it's 50x thinner than the aluminum. But at least generic paint is a rotten thermal conductor - this report (http://www.thefreelibrary.com/Special+heat+capacity+and+thermal+conductivity.-a0228354685) claims 0.17 w/m/K, or about 1000x worse than aluminum. So even if it's only 1/50th as thick, it's still a 20x better insulator than the aluminum. However, this would still need a flux of 20 kw/m^2 to maintain a delta-T of 11 degrees. This online heat transfer calculator (http://www.efunda.com/formulae/heat_transfer/convection_forced/calc_lamflow_isothermalplate.cfm#calc) estimates heat transfer from a 70K plate in a 4 m/s wind to be about 2kw/m^2, so the surface will still be much closer to 66K than 77K.<snip>
Will the outside of the rocket be less than 77K? Yes, if the inside is at 66K. The thermal conductivity of aluminum is about 205 w/m/k. So to get an 11K drop across a 5 mm thickness you would need a heat flow of 205*11/0.005 = 451 kw/m^2. No way you have that from condensing air, so the outside temp is less than 77K.
<snip>
Surely this calculation would only apply if the outside of the rocket were unpainted Al? But we know it's painted, and upthread I admitted complete ignorance about what kind of paint, and how thick (and how potentially explosive in contact with LOX ...). Does anyone here know these details?
Just so I've got the LOx-from-air scenario clear...
1. The outside of the tank must be far enough below 90K to prevent condensing LOx from evaporating.
2. The condensation of oxygen must not have happened on the vastly longer first stage oxygen tanks during any of the horizontal test burns performed since SpaceX started working on subcooling LOx, such that no-one noticed the LOx dripping off and said "Hey do we have a LOx leak", and investigated the issue. Nor noticed on either stage in any previous vertical static-fire or launch.
3. Something must rub off the ice to expose the bare tank wall. So...
4. As the F9 shrinks due to the second stage LOx fill (but after shrinkage caused by the previous main stage LOx fill), the small support brace below the hydraulic/pneumatic grapples, resting against the reinforced area that rings of the common bulkhead, must slide enough to scrape ice off that aforementioned reinforced area that rings the common bulkhead.
5. The thicker external skin of the ring around the common bulkhead must also be far enough below 90K for LOx to form faster than it evaporates.
6. The LOx forming on the newly exposed skin at the bottom of the common bulkhead ring must run... up?... to soak into the protective "plastic" pads of the support brace.
7. The protective "plastic" pads of the support brace, connected to the metal of the support brace, must also be far enough below 90K to prevent the soaking LOx from evaporating or just boiling away.
8. Something something then causes the below-90K "plastic" to catch fire.
9. ...causing our initial explosion.
7. The protective "plastic" pads of the support brace, connected to the metal of the support brace, must also be far enough below 90K to prevent the soaking LOx from evaporating or just boiling away.
7. The protective "plastic" pads of the support brace, connected to the metal of the support brace, must also be far enough below 90K to prevent the soaking LOx from evaporating or just boiling away.
So is the fix as simple as replace the pads with something lox compatible?
Would woven fiberglass cloth be a good choice?
Seems that people here are fixing a problem that has not been shown to even exist yet.
Seems that people here are fixing a problem that has not been shown to even exist yet.
and may never be shown to exist!
I want to suggest the possibility of using the MIT software mentioned in the video below. Anyone have access to it or know someone who might be able to run that footage through it? It takes very tiny movements and exaggerates them greatly, really cool actually. And it can be used after the footage has already been taken.
https://www.youtube.com/watch?v=3rWycBEHn3s
It seems that, with all the post-incident imagery of LC40, it would be a simple thing to determine if the pads are still present, thus ruling out this scenario.Seems that people here are fixing a problem that has not been shown to even exist yet.
and may never be shown to exist!
Well thinking about that.
Would the pads have to be missing from the TEL?
Could that be the proof?
Would a surface layer of the pads be enough to form the initial blast?
Why is putting weight on the vehicle and not the GSE a good idea?
7. The protective "plastic" pads of the support brace, connected to the metal of the support brace, must also be far enough below 90K to prevent the soaking LOx from evaporating or just boiling away.
So is the fix as simple as replace the pads with something lox compatible?
Would woven fiberglass cloth be a good choice?
It might be better to add a layer of insulation around the LOX tank (or at critical areas). While everyone would hate to add weight to the 2nd stage, preventing LOX from forming in the first place may well be the better solution.
LOX condensation.
This is the first complete explanation of the initial burst. The only thing missing is what material the pads are made out of. I have heard rubber? Is that confirmed by somebody?
I want to suggest the possibility of using the MIT software mentioned in the video below. Anyone have access to it or know someone who might be able to run that footage through it? It takes very tiny movements and exaggerates them greatly, really cool actually. And it can be used after the footage has already been taken.
https://www.youtube.com/watch?v=3rWycBEHn3s
They have a web site where you can upload your own video and process and see the motion amplification.
Sign up for an account, login, upload your video, watch....
https://lambda.qrilab.com/site/
Seems that people here are fixing a problem that has not been shown to even exist yet.Perfectly true, but you might want to fix it anyway (unless your analysis can firmly prove it's impossible), even if it's not the cause of this particular mishap.
Also: would SpaceX continue to be baffled by the source if this were the answer? They know exactly what the pads are made of, how they are cleaned, and what condition they are currently in. Don't you think they would be quickly wrapping up this investigation if they saw the pads were made of a LOX-incompatible plastic, that one of the pads was unaccounted for, and there were witness marks on the cradle arms?
Good point. I ignored the paint since it's very thin, but it turns out that's a bad guess. Assuming the paint is 0.1mm thick (since they don't want any extra mass),
1. "Pressing" and "Forcefully sliding" - until the clamps let go, they are surely pressing on the far side of the rocket. No way they would have an air gap and let the rocket rattle back and forth against the clamps - that would confuse the telemetry if nothing else. So until the arms are opened, the rocket will be pressed into the pad on the erector.
2.And thermal contraction generates big forces, so it will slide despite being pushed against the rocket.
Vortex shedding has caused the destruction of several large chimneys in the past,
<nested quotes snipped>
Yes, and far upthread envy887 made this point too. It happens that 77 K (as well as being LN2 bp) is also the temp at which LOX vapour pressure equals 20 kPa, the (sea-level) partial pressure of atmospheric O2. So between 77 K and 90 K LOX will evaporate faster than it condenses, even though it doesn't boil. Below 77 K condensation wins (at sea-level).
Even more significantly, at 75 K the vapour pressure of LN2 equals 80 kPa, the partial pressure of N2 in the atmosphere. Which means that between 75 and 77, LOX condenses while LN2 evaporates, and you will get pure LOX in your frost.
SpaceX seem to be the first to venture into this hazardous temperature range - the NK-33 family don't cool that far, because they rely on evaporating atmospheric-pressure LN2 to do the cooling. According to Spaceflight101 at http://spaceflight101.com/spacerockets/soyuz-2-1v/ the N-1 cooled to 81 K, Antares-100 to 78 K and the current Soyuz 2-1v to 86 K. Since these are all above 77 K, atmospheric LOX could never condense on the outside of their tanks, insulated or not.
On the other hand, LH2 rockets, as Rei says just upthread, got less dangerous liquid air because they were far below both 75 K and 77 K.
I think this temperature range, 75 to 77 K, is very significant. If your paint surface is that cold you are essentially distilling pure LOX from the air. And if it happens at the inside of the frost layer, cryopumping will quickly draw in more oxygen to build up the LOX. From the estimated heat flux through tankwall and paint, and the latent heat of O2, we could estimate the speed of build-up ...
LOX is incompatible with almost all organics (excepting fluoropolymers, to some extent), .
Why is putting weight on the vehicle and not the GSE a good idea?
7. The protective "plastic" pads of the support brace, connected to the metal of the support brace, must also be far enough below 90K to prevent the soaking LOx from evaporating or just boiling away.
So is the fix as simple as replace the pads with something lox compatible?
Would woven fiberglass cloth be a good choice?
It might be better to add a layer of insulation around the LOX tank (or at critical areas). While everyone would hate to add weight to the 2nd stage, preventing LOX from forming in the first place may well be the better solution.
This seems the first thing to check. Combine LOX and a pad and if it's still safe, this is not the explanation.LOX condensation.
This is the first complete explanation of the initial burst. The only thing missing is what material the pads are made out of. I have heard rubber? Is that confirmed by somebody?
If the pads are made of PFTE, there is no scenario here.
Even if the pads were made of an organic, I don't think there's been any credible ignition source shown. Jim has pretty persuasively argued that there is no banging or bumping involved, and he has first hand experience, and there's no evidence for rocking or swaying from the video either. Further, the magnitude and speed of the initial event seems incompatible with the amount and type of fuel proposed.The ignition source does not seem to be a huge obstacle. Stuff combined with LOX is quite sensitive to mechanical shock, and the rocket is not still. The first stage is still shrinking (it's not full until T-2:40), and the LOX will be boiling. As Cernan says in "Last Man on the Moon", while going up the elevator "Every inch of the way, the rocket beside us hummed and vibrated. Glasslike chunks of ice slid away as her cryogenic life-blood, liquid oxygen and liquid hydrogen, boiled and bubbled in her guts." Whether or not you can get enough LOX-pad combo to explain the initial explosion required data we do not have.
Also: would SpaceX continue to be baffled by the source if this were the answer? They know exactly what the pads are made of, how they are cleaned, and what condition they are currently in. Don't you think they would be quickly wrapping up this investigation if they saw the pads were made of a LOX-incompatible plastic, that one of the pads was unaccounted for, and there were witness marks on the cradle arms?This to me is the strongest objection - such an event should leave signs in the wreckage, and SpaceX would not be puzzled. I'd assume they must have examined the T/E by now, although this will presumable be easier and more thorough once they can lower it.
This to me is the strongest objection - such an event should leave signs in the wreckage, and SpaceX would not be puzzled. I'd assume they must have examined the T/E by now, although this will presumable be easier and more thorough once they can lower it.
Good point. I ignored the paint since it's very thin, but it turns out that's a bad guess. Assuming the paint is 0.1mm thick (since they don't want any extra mass), then it's 50x thinner than the aluminum. But at least generic paint is a rotten thermal conductor - this report (http://www.thefreelibrary.com/Special+heat+capacity+and+thermal+conductivity.-a0228354685) claims 0.17 w/m/K, or about 1000x worse than aluminum. So even if it's only 1/50th as thick, it's still a 20x better insulator than the aluminum. However, this would still need a flux of 20 kw/m^2 to maintain a delta-T of 11 degrees. This online heat transfer calculator (http://www.efunda.com/formulae/heat_transfer/convection_forced/calc_lamflow_isothermalplate.cfm#calc) estimates heat transfer from a 70K plate in a 4 m/s wind to be about 2kw/m^2, so the surface will still be much closer to 66K than 77K.<snip>
Will the outside of the rocket be less than 77K? Yes, if the inside is at 66K. The thermal conductivity of aluminum is about 205 w/m/k. So to get an 11K drop across a 5 mm thickness you would need a heat flow of 205*11/0.005 = 451 kw/m^2. No way you have that from condensing air, so the outside temp is less than 77K.
<snip>
Surely this calculation would only apply if the outside of the rocket were unpainted Al? But we know it's painted, and upthread I admitted complete ignorance about what kind of paint, and how thick (and how potentially explosive in contact with LOX ...). Does anyone here know these details?
1. They aren't clamping the vehicle tight. It is just there to steady the vehicle. It is not holding the vehicle. It is like a boat bumper.
There are pictures posted which show they've had a crane up at the site for inspections. I don't think they'll bring the T/E down until they've concluded their investigation, or ruled out the GSE.This to me is the strongest objection - such an event should leave signs in the wreckage, and SpaceX would not be puzzled. I'd assume they must have examined the T/E by now, although this will presumable be easier and more thorough once they can lower it.
That was my next question. Have they lowered it yet?
I think something conclusive will come out of having it lowered and thoroughly examined.
and may never be shown to exist!
Well thinking about that.
Would the pads have to be missing from the TEL?
Could that be the proof?
Would a surface layer of the pads be enough to form the initial blast?
The first stage is still shrinking (it's not full until T-2:40), and the LOX will be boiling.
and may never be shown to exist!
Well thinking about that.
Would the pads have to be missing from the TEL?
Could that be the proof?
Would a surface layer of the pads be enough to form the initial blast?
And may have acted as a "shaped charge" because of the metal frame it was in. Directing most of the force toward the vehicle just ABOVE the re-enforced portion of the stage because the rocket had shrunk and slid downwards.
Hypothesis:Please. Exploding flies?
1. A fly or similar insect is attracted by the white surface and sits down
Really? This is the rational thread.
Here is the wacky thread.
http://forum.nasaspaceflight.com/index.php?topic=41119.0
In fact, all the LOX and bumper talk should move there. Too many things have to happen for this to be feasible
... and we need to take into account the effect of the release of latent heat by the LOX as it condenses (if it does).
My point here is that the release of latent heat of condensation will act like a thermostat [...]
This would still be very localized when a few milliseconds later it has burnt through the tank wall [...]
1. The outside of the tank must be far enough below 90K to prevent condensing LOx from evaporating.Technically, it's condensing faster than it's evaporating. This is know to happen with LN2 (see references). The outside is colder than LN2 (see calculations).
Our objection I think, is, as of today, in your view, the Falcon would not have exploded.
What happens to high pressure (2000-4000 psi) Helium at 77k or 280k when released through a small diameter tube?It shards at the end. Unless you reinforce it.
This to me is the strongest objection - such an event should leave signs in the wreckage, and SpaceX would not be puzzled. I'd assume they must have examined the T/E by now, although this will presumable be easier and more thorough once they can lower it.
That was my next question. Have they lowered it yet?
I think something conclusive will come out of having it lowered and thoroughly examined.
What happens to high pressure (2000-4000 psi) Helium at 77k or 280k when released through a small diameter tube?It shards at the end. Unless you reinforce it.
it will be below LOX condensation temperature,
It only takes a bit of dirt or sand to scrape the paint
What happens to high pressure (2000-4000 psi) Helium at 77k or 280k when released through a small diameter tube?It shards at the end. Unless you reinforce it.
I mean the temp of the helium as it exits
I wouldn't mind seeing the blast signature of an exploding Lithium Ion battery in the confined area of an interstage test... Just to compare to what we saw...
What happens to high pressure (2000-4000 psi) Helium at 77k or 280k when released through a small diameter tube?It shards at the end. Unless you reinforce it.
I mean the temp of the helium as it exits
Joule-Thomson effect. It gets warm.
No, my view is that incident had nothing to do with pads or LOX forming.
What happens to high pressure (2000-4000 psi) Helium at 77k or 280k when released through a small diameter tube?
What happens to high pressure (2000-4000 psi) Helium at 77k or 280k when released through a small diameter tube?It shards at the end. Unless you reinforce it.
I mean the temp of the helium as it exits
Joule-Thomson effect. It gets warm.
Will it get hot?
It only takes a bit of dirt or sand to scrape the paint off the aluminum and create a bare surface and some activation energy.
In the area of the recent F9 flash there are 14 hydraulic connectors. If one was leaking?
What happens to high pressure (2000-4000 psi) Helium at 77k or 280k when released through a small diameter tube?It shards at the end. Unless you reinforce it.
I mean the temp of the helium as it exits
Joule-Thomson effect. It gets warm.
Will it get hot?
As with all such questions, the answer is...it depends. On the hole size, location, edge geometry of the crack or pinhole, etc. Could be a real science project trying to prove.
What happens to high pressure (2000-4000 psi) Helium at 77k or 280k when released through a small diameter tube?It shards at the end. Unless you reinforce it.
I mean the temp of the helium as it exits
Joule-Thomson effect. It gets warm.
Will it get hot?
As the broken part was failing, helium would be expanding from the high-pressure tanks to the low pressure of the atmosphere, but this doesn't seem to explain the result, since the Joule-Thomson coefficient of helium is only around .065 degrees K/atm, so going from 6000 psi to atmospheric pressure should only heat it up about 27 degrees C or K.
So, if the ambient temperature is ~75 degrees F, then it wouldn't get any hotter than ~125 degrees F.
a. LOX does not form on the vehicle. (tank and paint thickness prevent it) No need to go any further but to appease the LOX accusers
It will rise due to the Joule-Thomson effect, but this seems too small to be any problem. From the paper "The Joule-Thomson Effect in Helium", by J. R. Roebuck and H. Osterberg (http://journals.aps.org/pr/abstract/10.1103/PhysRev.43.60) the effect is about 0.06 degrees C/atm of pressure drop. So if the pressure drop is 500 atm (a very high helium pressure) the rise in temperature is 30 degrees C. This does not seem to be enough to add any significant problem to the pressure spike, mechanical damage, etc. that the bursting tank already causes.I mean the temp of the helium as it exitsWhat happens to high pressure (2000-4000 psi) Helium at 77k or 280k when released through a small diameter tube?It shards at the end. Unless you reinforce it.
It will rise due to the Joule-Thomson effect, but this seems too small to be any problem. From the paper "The Joule-Thomson Effect in Helium", by J. R. Roebuck and H. Osterberg (http://journals.aps.org/pr/abstract/10.1103/PhysRev.43.60) the effect is about 0.06 degrees C/atm of pressure drop. So if the pressure drop is 500 atm (a very high helium pressure) the rise in temperature is 30 degrees C. This does not seem to be enough to add any significant problem to the pressure spike, mechanical damage, etc. that the bursting tank already causes.I mean the temp of the helium as it exitsWhat happens to high pressure (2000-4000 psi) Helium at 77k or 280k when released through a small diameter tube?It shards at the end. Unless you reinforce it.
A problem with this is that there appears to be no evidence on telemetry. From videos of scuba tank ruptures (https://www.youtube.com/watch?v=f-xmaPSZ6GM), it takes a tank many seconds to empty through a hole. In addition, this won't overpressurize the tank unless the ullage is quite small, which it is not at this stage of loading.
No, my view is that incident had nothing to do with pads or LOX forming.
What happens to high pressure (2000-4000 psi) Helium at 77k or 280k when released through a small diameter tube?
It will rise due to the Joule-Thomson effect, but this seems too small to be any problem. From the paper "The Joule-Thomson Effect in Helium", by J. R. Roebuck and H. Osterberg (http://journals.aps.org/pr/abstract/10.1103/PhysRev.43.60) the effect is about 0.06 degrees C/atm of pressure drop. So if the pressure drop is 500 atm (a very high helium pressure) the rise in temperature is 30 degrees C. This does not seem to be enough to add any significant problem to the pressure spike, mechanical damage, etc. that the bursting tank already causes.I mean the temp of the helium as it exitsWhat happens to high pressure (2000-4000 psi) Helium at 77k or 280k when released through a small diameter tube?It shards at the end. Unless you reinforce it.
1. Plus the thermal inertia of the cold LOX.
2. Plus, how did this supposed event manage to form a large ball, practically at the speed of sound, within 16-30 mSec out side of the tank, without signs of the tank bursting?
3. I agree that the pressurized He tanks are a tempting source of energy in an environment that is otherwise supposed to be benign, but I think the key here is "supposed to be".
I wouldn't mind seeing the blast signature of an exploding Lithium Ion battery in the confined area of an interstage test... Just to compare to what we saw...
Problem with this as a cause is that the characteristics of Li-Ion batteries are very well known. They would certainly have them electrically and thermally protected, and should be instrumented as well, since they are known to do bad things when abused.
While we don't have enough information to rule them out and such a test would be interesting, I think SpaceX would already have identified it if this were the cause.
If we know everything about them, then the questions are why do seem surprised when we see a problem come up in commercial products, aviation and automotive application? They also have the stored energy for an explosion and I don't know the types of telemetry on them nor their state at the time... What else is in the interstage area have that much potential explosive energy?I wouldn't mind seeing the blast signature of an exploding Lithium Ion battery in the confined area of an interstage test... Just to compare to what we saw...
Problem with this as a cause is that the characteristics of Li-Ion batteries are very well known. They would certainly have them electrically and thermally protected, and should be instrumented as well, since they are known to do bad things when abused.
While we don't have enough information to rule them out and such a test would be interesting, I think SpaceX would already have identified it if this were the cause.
Edit to add: also at this point in the countdown, batteries would be fully charged for some time and just on trickle. They do not tend to have problems in this state.
So what's your point? Top experts that design cars that burn to the ground, rockets that blow-up on the pad and inflight. Perhaps you should take them down from your "god-like" worship of them and that they are mere mortals that can fail like the rest of us…I wouldn't mind seeing the blast signature of an exploding Lithium Ion battery in the confined area of an interstage test... Just to compare to what we saw...
Problem with this as a cause is that the characteristics of Li-Ion batteries are very well known. They would certainly have them electrically and thermally protected, and should be instrumented as well, since they are known to do bad things when abused.
While we don't have enough information to rule them out and such a test would be interesting, I think SpaceX would already have identified it if this were the cause.
Yeah... In addition to rocket science, Elon apparently knows a thing or two about Li-Ion batteries. Don't forget that his other hobby is building fast cars with batteries and revolutionizing the manufacturing Li-Ion batteries on a global scale. He no doubt has an impressive percentage of the worlds top Li-Ion experts on his payroll.
If there was any reason to believe that an exploding battery might be somehow implicated in this event, his accident investigation team would certainly have that base covered.
Yeah... In addition to rocket science, Elon apparently knows a thing or two about Li-Ion batteries. Don't forget that his other hobby is building fast cars with batteries and revolutionizing the manufacturing Li-Ion batteries on a global scale. He no doubt has an impressive percentage of the worlds top Li-Ion experts on his payroll.
If there was any reason to believe that an exploding battery might be somehow implicated in this event, his accident investigation team would certainly have that base covered.
1. Plus the thermal inertia of the cold LOX.
2. Plus, how did this supposed event manage to form a large ball, practically at the speed of sound, within 16-30 mSec out side of the tank, without signs of the tank bursting?
3. I agree that the pressurized He tanks are a tempting source of energy in an environment that is otherwise supposed to be benign, but I think the key here is "supposed to be".
1. Doesn't play into it.
2. What ball or tank?
3. I am thinking plumbing and not tanks and some of the lines have to be on the exterior of the vehicle.
4. The first flash was outside the vehicle per the video.
If you go back to the original USLR video, you will see that the area identified is often completely obscured by dark venting. When not obscured, it is a bright area, so perhaps it should not be surprising that it changes more than any other area?
I think you may have missed the whole point of the analysis. The area identified had the recurring changes removed and only the differential change between the prior interval and the moments before the incident remain.
In the video stream, that region appears to grow light & dark over time. It's consistent in behavior with the obvious venting seen to the left of the F9.
Basically, we've composited 11 seconds worth of frames into one frame, skipped about 9 seconds, and composited the last second into one frame, and then looked at any significant differences. (Don't do this at home without adult supervision)
Vortex shedding has caused the destruction of several large chimneys in the past,
That is the reason the strong back is there and remains attached to the rocket so late into the count, is to prevent vortex shedding from damaging the vehicle. The upper clamp points would be taking into account the natural frequency and modes of the vehicle.
In the 1 mm paint + 28 mm frost model above, which completely ignored the latent heat released by the (hypothetical) condensing LOX, the heat flux through paint and frost together was about:a. LOX does not form on the vehicle. (tank and paint thickness prevent it) No need to go any further but to appease the LOX accusers
Ha! I indignantly reject the labels of LOX-hoaxer and LOX-accuser. The polite term for us is "LOX-frosters".
Here is the calculation that convinces me that LOX condensation is possible. It's based on my post back around page 121 , but with actual numbers for conductivities.
First, can we agree that a layer of frost, of some unspecified thickness, does form on the outside of the LOX tanks when they’re full or filling? After all, there is enough left to stop the white parts of the returned stages getting sooted-up, and there must be more before the launch vibrations shake it off. It starts forming when filling chilldown begins, no cryo temps yet, so starts like ordinary fridge-frost and then thickens to form an insulating blanket.
I contend that the temperature of the paint/frost surface depends crucially on the thickness and fluffiness of this frost layer, which I guess to be more or less like dry snow. After all, if you wrapped the rocket in a perfectly insulating blanket, the outside of the paint on the LOX tank would quickly fall to the temperature of the LOX inside. The question is, how thin can this blanket be made before that temperature rises above 77 K?
As for numbers, LouScheffer in #2694 gives a thermal conductivity of 0.17 W/m/K for generic paint. Wikipedia's "List of thermal conductivities" gives 0.05, 0.11, and 0.25 W/m/K for "dry snow". So as a first approximation, we might take the conductivities of paint and frost to be about equal.
Then with the same very rough numbers I've used in an earlier post:
tank Al/paint surface: 70 K
paint/frost surface: 77 K for the limiting case
frost/air surface: 273 K
delta-T across paint: 7 K
delta-T across frost: 196 K
Assuming equal thermal conductivities, the frost will have to be 196/7 = 28 times thicker than the paint. If the frost is thicker than this, the paint/frost surface will be colder than 77 K.
How realistic is "28 times thicker"? Well, say 1 mm for quite thick paint; then the frost would have to be thicker than 28 mm. Isn't this quite realistic? about an inch? (Obviously my numbers could easily be out by a factor of 2 or more, but we are still talking about inches.)
But then of course the inch of frost has to be fluffy and porous enough for O2 to diffuse in through it to the paint surface and condense there. Isn't this quite plausible? Once the condensation starts, cryopumping will pull in more air quite forcefully.
From the outside, there would be no visible sign of the LOX under the frost.
1. Plus the thermal inertia of the cold LOX.
2. Plus, how did this supposed event manage to form a large ball, practically at the speed of sound, within 16-30 mSec out side of the tank, without signs of the tank bursting?
3. I agree that the pressurized He tanks are a tempting source of energy in an environment that is otherwise supposed to be benign, but I think the key here is "supposed to be".
1. Doesn't play into it.
2. What ball or tank?
3. I am thinking plumbing and not tanks and some of the lines have to be on the exterior of the vehicle.
4. The first flash was outside the vehicle per the video.
Let's take an assumption. A helium line feed at 5,000 PSI near (+- 5 feet?) an RP1 line feed that has ambient RP1 liquid just sort of sitting there at any temperature. (Question, once the fueling is complete, is the feed line drained, or is it simply relieved of pumping pressure?)
Pretend the helium line feed ruptures. The pieces of the feed will travel at between 400 and 900 ft/second (barrel pressure and projectile velocity in gun systems calculator, google it). The gas speed will be much higher, depending on the calculator de jour and other unknowns.
Let's take an assumption. A helium line feed at 5,000 PSI near (+- 5 feet?) an RP1 line feed that has ambient RP1 liquid just sort of sitting there at any temperature. (Question, once the fueling is complete, is the feed line drained, or is it simply relieved of pumping pressure?)
Pretend the helium line feed ruptures. The pieces of the feed will travel at between 400 and 900 ft/second (barrel pressure and projectile velocity in gun systems calculator, google it). The gas speed will be much higher, depending on the calculator de jour and other unknowns.
Yeah, I mentioned something along those lines abut 23 hours ago ...
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1583473#msg1583473
... though I didn't detail the specifics; in fact, internal helium lines in the interstage are actually near some potentially vulnerable bits, not just the umbilicals: the S2 MVac and associated hydraulics, the bottom of the S2 RP1 tank, power and data lines for sensors and engine control systems; similar avionics in the interstage for S1 guidance and landing, etc.
Yeah, I mentioned something along those lines abut 23 hours ago ...
http://forum.nasaspaceflight.com/index.php?topic=30981.msg1583473#msg1583473
... though I didn't detail the specifics; in fact, internal helium lines in the interstage are actually near some potentially vulnerable bits, not just the umbilicals: the S2 MVac and associated hydraulics, the bottom of the S2 RP1 tank, power and data lines for sensors and engine control systems; similar avionics in the interstage for S1 guidance and landing, etc.
..isn't there TEA-TEB plumbing/vessel around there as well? ...
The amplitude of the movement need only be millimetres, and so may not be visible on camera. The frequency of any oscillation could be deeply subsonic, and also may not have been detected.
The amplitude of the movement need only be millimetres, and so may not be visible on camera. The frequency of any oscillation could be deeply subsonic, and also may not have been detected.
Launch vehicles are not that delicate. They can flex more than millimetres and the frequency would be low. And accelerometers would detect the movement and frequency.
..isn't there TEA-TEB plumbing/vessel around there as well? ...
No. TEA-TEB is loaded in the HIF, I'm told.
Let's take an assumption. A helium line feed at 5,000 PSI near (+- 5 feet?) an RP1 line feed that has ambient RP1 liquid just sort of sitting there at any temperature. (Question, once the fueling is complete, is the feed line drained, or is it simply relieved of pumping pressure?)
Pretend the helium line feed ruptures. The pieces of the feed will travel at between 400 and 900 ft/second (barrel pressure and projectile velocity in gun systems calculator, google it). The gas speed will be much higher, depending on the calculator de jour and other unknowns.
If the rupture is directional, it not only ruptures the RP1 line, but also creates an RP1 aerosol (and probably has enough frictional energy for ignition by the stray parts), Creating an aerosol of .4 kg of RP1 and , if I'm reading this right, creates and ignites a 15 ft column of vapor in 16 milliseconds. 1 frame time from rupture to detonation. If the rupture occurs somewhere in frame 0, we can't see it because it's too fast. If the (sorry Jim, I know you said no more FAE discussions) FAE occurs near the beginning of the Frame 1 capture, it's too late to see what happened in Frame 0, because, well, it's obscured by a fireball saturating the camera.
As far as monitoring goes, Spacex actually sees the HE line pressure drop, but the drop may only be visible after the event has occurred, and easily attributed to being caused by the event, rather than the cause of the event. To see the HE event, they would have to be sampling the HE line at near 1 millisecond intervals.
OK, back to my regularly scheduled program. Anyone want to buy a few kilos of organic potatoes? :)
In the area of the recent F9 flash there are 14 hydraulic connectors. If one was leaking?
Traveller, I don't think those lines you've marked are part of the hydraulics. I believe they are the cables that connect the umbilicals to the counter-weight pipe that hangs further down the TEL.
They are not counter-weight wires. They are hydraulic lines that have been cut and extended. Note the 14 in line connectors at each end of the extension section. You can see them toasted in the attached. See if you can count 7 lines as in the original image.
They are not counter-weight wires. They are hydraulic lines that have been cut and extended. Note the 14 in line connectors at each end of the extension section. You can see them toasted in the attached. See if you can count 7 lines as in the original image.
Ah, that's what they are - saw the bent pipes in the one of the 'after' images and wondered.
Presumably the bending is the result of the top of the strongback collapsing; and in turn their condition implies that those are steel pipes of a relatively small diameter, which reinforces the supposition that they're hydraulics pipes.
They are in a location that's consistent with the start of the explosion; and they are under sufficient pressure that a leak would result in vapour.
The fundamental question would be whether or not the fluid used is explosive in an oxygen-rich environment.
Let's take an assumption. A helium line feed at 5,000 PSI near (+- 5 feet?) an RP1 line feed that has ambient RP1 liquid just sort of sitting there at any temperature. (Question, once the fueling is complete, is the feed line drained, or is it simply relieved of pumping pressure?)
Pretend the helium line feed ruptures. The pieces of the feed will travel at between 400 and 900 ft/second (barrel pressure and projectile velocity in gun systems calculator, google it). The gas speed will be much higher, depending on the calculator de jour and other unknowns.
If the rupture is directional, it not only ruptures the RP1 line, but also creates an RP1 aerosol (and probably has enough frictional energy for ignition by the stray parts), Creating an aerosol of .4 kg of RP1 and , if I'm reading this right, creates and ignites a 15 ft column of vapor in 16 milliseconds. 1 frame time from rupture to detonation. If the rupture occurs somewhere in frame 0, we can't see it because it's too fast. If the (sorry Jim, I know you said no more FAE discussions) FAE occurs near the beginning of the Frame 1 capture, it's too late to see what happened in Frame 0, because, well, it's obscured by a fireball saturating the camera.
As far as monitoring goes, Spacex actually sees the HE line pressure drop, but the drop may only be visible after the event has occurred, and easily attributed to being caused by the event, rather than the cause of the event. To see the HE event, they would have to be sampling the HE line at near 1 millisecond intervals.
OK, back to my regularly scheduled program. Anyone want to buy a few kilos of organic potatoes? :)
From the video there seems to be a dark dense fragment which flies up and to the right. It seems to be about 15-20 cm in diameter and follows a ballistic trajectory, gradually slowing down and dropping sightly from a straight line. The interesting thing about this fragment is that it seems to originate from below the "explosion", but still goes upwards.
http://forum.nasaspaceflight.com/index.php?topic=40157.msg1583295#msg1583295
If this is not a bird or bug (and what is presumably a bird follows a similar trajectory starting at the bottom left corner in frame 13), then it is a prime candidate for what could rupture the fuel line.
They are not counter-weight wires. They are hydraulic lines that have been cut and extended. Note the 14 in line connectors at each end of the extension section. You can see them toasted in the attached. See if you can count 7 lines as in the original image.
Ah, that's what they are - saw the bent pipes in the one of the 'after' images and wondered.
Presumably the bending is the result of the top of the strongback collapsing; and in turn their condition implies that those are steel pipes of a relatively small diameter, which reinforces the supposition that they're hydraulics pipes.
They are in a location that's consistent with the start of the explosion; and they are under sufficient pressure that a leak would result in vapour.
The fundamental question would be whether or not the fluid used is explosive in an oxygen-rich environment.
I like your idea but Jim has ruled out flammable hydraulic fluid in a previous post.
The amplitude of the movement need only be millimetres, and so may not be visible on camera. The frequency of any oscillation could be deeply subsonic, and also may not have been detected.
Launch vehicles are not that delicate. They can flex more than millimetres and the frequency would be low. And accelerometers would detect the movement and frequency.
Yes, the vehicle can flex, but the lower pad can't. That's the problem, if the vehicle flexes towards it, the pad will puncture the fuselage.
How about this. Has anybody every gotten there finger or tongue frozen to a aluminum pole in the winter?
They are not counter-weight wires. They are hydraulic lines that have been cut and extended. Note the 14 in line connectors at each end of the extension section. You can see them toasted in the attached. See if you can count 7 lines as in the original image.
Ah, that's what they are - saw the bent pipes in the one of the 'after' images and wondered.
Presumably the bending is the result of the top of the strongback collapsing; and in turn their condition implies that those are steel pipes of a relatively small diameter, which reinforces the supposition that they're hydraulics pipes.
They are in a location that's consistent with the start of the explosion; and they are under sufficient pressure that a leak would result in vapour.
The fundamental question would be whether or not the fluid used is explosive in an oxygen-rich environment.
I like your idea but Jim has ruled out flammable hydraulic fluid in a previous post.
In the attached dual images, the flash on the right is the 1st frame of a LOX & Oil flash. On the left is the 1st frame of the F9 flash. As the central colour and the 2 fringing colours appear to match each other, just maybe the initial F9 flash was a LOX and Oil flash.
Then add in there were 14 in-line hydraulic connectors, to support the F9 FT TEL extension and that those 14 connectors are where the centre of the initial F9 flash occurred.
Found a shot of Amos6, clearly showing the hydraulic line joiners where the 1st flash occurred.
Traveler... LTNS :)
Attached is a representative photo from a stream of 1,307 we processed to remove air turbulence.
Taking the 1st 10 seconds into a single stacked image, skipping 9 seconds, then stacking the last second, there was one exactly one clear difference region circled in the attached representative image.
Interpreted to be nothing more than an air-gap between the TE and F9, exactly where are your upper and lower circles WRT to that air gap?
They are not counter-weight wires. They are hydraulic lines that have been cut and extended. Note the 14 in line connectors at each end of the extension section. You can see them toasted in the attached. See if you can count 7 lines as in the original image.
Ah, that's what they are - saw the bent pipes in the one of the 'after' images and wondered.
Presumably the bending is the result of the top of the strongback collapsing; and in turn their condition implies that those are steel pipes of a relatively small diameter, which reinforces the supposition that they're hydraulics pipes.
They are in a location that's consistent with the start of the explosion; and they are under sufficient pressure that a leak would result in vapour.
The fundamental question would be whether or not the fluid used is explosive in an oxygen-rich environment.
I like your idea but Jim has ruled out flammable hydraulic fluid in a previous post.
clearly shows the hydraulics. Later in that thread is a closeup.
We don't know if it is hydraulics, it could be pneumatics.
if the vehicle flexes towards it, the pad will puncture the fuselage.
Traveler... LTNS :)
Attached is a representative photo from a stream of 1,307 we processed to remove air turbulence.
Taking the 1st 10 seconds into a single stacked image, skipping 9 seconds, then stacking the last second, there was one exactly one clear difference region circled in the attached representative image.
Interpreted to be nothing more than an air-gap between the TE and F9, exactly where are your upper and lower circles WRT to that air gap?
As attached. The 14 hydraulic line jointing connectors are where the centre of what looks like a LOX & Oil flash occurred.
If one of the 14 joints failed and it was spraying hydraulic fluid and/or vapour into the air, I doubt you would see that on the images. That is until it mixed with enough venting LOX to ignite.
]
They are hydraulic lines that have been cut and extended. Note the 14 in line connectors at each end of the extension section. You can see them toasted in the attached. See if you can count 7 lines as in the original image.
c. The leak would be seen on other cameras
]
They are hydraulic lines that have been cut and extended. Note the 14 in line connectors at each end of the extension section. You can see them toasted in the attached. See if you can count 7 lines as in the original image.
A. Why would they be under pressure at that time?
b. why would there be 7 lines for only two actuators?
c. The leak would be seen on other cameras
d. How do you know they are hydraulic lines and not He and GN2 lines?
The Strongback was replaced for V1.1 and modified for FT. The V1.0 strongback was discarded.
c. The leak would be seen on other cameras
much as still it's my favorite theory, here's a real example. Things are much slower and far more visible than my favorite theory requires, and this is with a non-flame retardant hydraulic fluid.
Was the *entire* frame discarded
C - Yes, but we don't have access to them.
c. The leak would be seen on other cameras
much as still it's my favorite theory, here's a real example. Things are much slower and far more visible than my favorite theory requires, and this is with a non-flame retardant hydraulic fluid.
The aerosoled fluid did not burn
I've been looking at the actual initial 'deflagation', after T=0 and found there is quite a lot to see in the Blue channel, the red and green being saturated. The center of the initial saturated area actually has a hole in the blue channel. This questions me: how comes? Does not look like a vapor cloud to me, but probably the part was obscured by some thing on the TEL?
Glenn, great work on the video.
I've been looking at the actual initial 'deflagation', after T=0 and found there is quite a lot to see in the Blue channel, the red and green being saturated. The center of the initial saturated area actually has a hole in the blue channel. This questions me: how comes? Does not look like a vapor cloud to me, but probably the part was obscured by some thing on the TEL?
Actually, I think you can make an educated guess about the size of that initial *kaboom* by following the development of the cloud.
I couldn't find any mention of this upthread, but I think it was already noticed that the "light-emitting body" in frame T=0 must have been smaller than the TEL, because its back is not illuminated
c. The leak would be seen on other cameras
much as still it's my favorite theory, here's a real example. Things are much slower and far more visible than my favorite theory requires, and this is with a non-flame retardant hydraulic fluid.
The aerosoled fluid did not burn
Welcome to the forum! :)They are not counter-weight wires. They are hydraulic lines that have been cut and extended. Note the 14 in line connectors at each end of the extension section. You can see them toasted in the attached. See if you can count 7 lines as in the original image.
Ah, that's what they are - saw the bent pipes in the one of the 'after' images and wondered.
Presumably the bending is the result of the top of the strongback collapsing; and in turn their condition implies that those are steel pipes of a relatively small diameter, which reinforces the supposition that they're hydraulics pipes.
They are in a location that's consistent with the start of the explosion; and they are under sufficient pressure that a leak would result in vapour.
The fundamental question would be whether or not the fluid used is explosive in an oxygen-rich environment.
I like your idea but Jim has ruled out flammable hydraulic fluid in a previous post.
First time poster... I'm not sure if I've seen this scenario so I apologize if it's already been mentioned. The Titan II silo accident in 1980 was caused by FOD dropped down into the silo (in that case a large socket) which bounced and pierced the skin creating an aerosol. The resultant explosion took out the entire missile and silo:Anther new guy, welcome to the forum! :)
http://www.encyclopediaofarkansas.net/encyclopedia/entry-detail.aspx?entryID=2543
Note that those were hypergolic propellants... In the SpaceX case, a large piece of FOD could have fallen off the strongback due to the high wind, bounced off one of the strongback beams and hit the skin of the fuel tank and created a pinhole leak. Hydrostatic pressure in the tank would be sufficient to generate an aerosol that would then mix with the vented LOX. Still need an ignition source though. Also you would think a camera would catch it but it wouldn't take much of an object to cause damage.
I've been looking at the actual initial 'deflagation', after T=0 and found there is quite a lot to see in the Blue channel, the red and green being saturated. The center of the initial saturated area actually has a hole in the blue channel. This questions me: how comes? Does not look like a vapor cloud to me, but probably the part was obscured by some thing on the TEL?
Is it possible that the ADC converter in the camera "rolled over" and went negative at the brightest point? Astronomical-grade CCD imagers will sometimes do this. If that "dark spot" is at the center of the diffraction "X", then it could actually mark the brightest spot, rolled over.
Jim.
No, it won't. It is not point load, it is spread out by the pad. And it is at the common bulkhead joint and not a tank side.
One issue I see with this theory is that the wind is blowing right to left (more or less) in the video. Therefore the round body of the rocket is in the lee of the TEL, thereby disrupting and partially blocking air flow to the rocketThe TE at pad 40 is the only one of the three that is not falcon heavy compatible.
How many other differences are there to the other two TEs?
Are the other 2 TEs identical?
If they are significantly different to the one at pad 40, and the problem is external to the vehicle, it could be good news for RTF.
The TE at pad 40 had the most launches, and had been modified several times for each version of the Falcon 9. Could that have contributed?
If you view the CRS-8 technical webcast, at T-04:10 there is a closeup of the grippers being released and the strongback being retracted. The cradle can be seen to tilt forward as the grippers release, indicating that at least the top cradle pad was in contact with the second stage up to that point. Once the grippers have released, the rocket begins to sway, occasionally enough to bump the top pad. I've attached an edit of the technical broadcast below.
Vortex shedding has caused the destruction of several large chimneys in the past, for example at the Ferrybridge C power station. A turbulent vortex street can occur around chimneys, provided that the flow has a Reynolds number (Re) greater than 3.5 x 10^6, where Re = v * L / ν.
Similarly, a turbulent vortex street could occur around the Falcon 9 rocket. The minimum turbulent Re for the Falcon 9 is when the velocity of the wind v = 3.5 x 10^6 * 0.00001458 / 3.7 = 13.79 m/s. This is a 26.8 knot breeze, which is strong, but not inconceivable, especially at height. If a vortex street is established, there will be oscillating horizontal forces applied to the rocket. Because it is pinned at the base and the gripper by the much stronger and stiffer TE, the flexion mode (but hopefully not the amplitude) could be as shown below. This is especially likely if the frequency of the oscillations is near the resonant frequency of the rocket, which will change as the fuel is loaded.
In the Thaicom8 closeup of the second stage, both the top and bottom pads are seen to be in contact with the stage whilst the grippers are closed. The problem is that when the gripper is closed, it prevents movement of the upper pad towards the stage. The cradle itself is also pinned by the TE, so the lower pad can't move away from the stage. The fuselage is only millimetres thick, so even a small oscillation of the rocket could have a catastrophic effect at the point of contact, the lower pad. Although a breach in the stage near the common bulkhead may not explain how ignition occurred, it would explain what lead up to it.
I'm not completely sure which thread this theory belongs in, but any feedback would be appreciated. I'm also not sure if the cradles at the other pads are identical.
The "lower pad" rests on a visibly-reinforced portion of S2 right where the common bulkhead exists inside the stage. It's probably the strongest portion of S2 aside from the thrust structure at the bottom of the RP1 tank. I've made this point several times over the last two weeks, but rockets just aren't that fragile and the designers aren't complete nincompoops when it comes to designing their support equipment.
c. The leak would be seen on other cameras
much as still it's my favorite theory, here's a real example. Things are much slower and far more visible than my favorite theory requires, and this is with a non-flame retardant hydraulic fluid.
The aerosoled fluid did not burn
Well actually part of it did, about 6,000 milliseconds later than my favorite theory requires, and it was a very slow deflagration to boot with an excellent ignition source available. I guess this real world example doesn't support the hydraulic mist theory very well... :'(
Glenn, great work on the video.
I've been looking at the actual initial 'deflagation', after T=0 and found there is quite a lot to see in the Blue channel, the red and green being saturated. The center of the initial saturated area actually has a hole in the blue channel. This questions me: how comes? Does not look like a vapor cloud to me, but probably the part was obscured by some thing on the TEL?
Actually, I think you can make an educated guess about the size of that initial *kaboom* by following the development of the cloud.
I couldn't find any mention of this upthread, but I think it was already noticed that the "light-emitting body" in frame T=0 must have been smaller than the TEL, because its back is not illuminated
The "lower pad" rests on a visibly-reinforced portion of S2 right where the common bulkhead exists inside the stage. It's probably the strongest portion of S2 aside from the thrust structure at the bottom of the RP1 tank. I've made this point several times over the last two weeks, but rockets just aren't that fragile and the designers aren't complete nincompoops when it comes to designing their support equipment.
"the designers aren't complete nincompoops"
Please Herb,
This is just a strawman. Nobody thinks or says this.
c. The leak would be seen on other cameras
much as still it's my favorite theory, here's a real example. Things are much slower and far more visible than my favorite theory requires, and this is with a non-flame retardant hydraulic fluid.
The aerosoled fluid did not burn
Pardon me if I'm mistaken, but wasn't the issue of a potential hydraulic leak brought up as a potential fuel source in the event of a leak of GOX, leak of LOX, condensation of LOX, or other O2-concentrating event (surrounding a tank full of LOX with a GOX headspace, pipes full of LOX, and all of the LOX in question lower than the boiling point of O2)?
If that was the hypothesis - again, please correct me if I'm wrong - then what's the relevance of hydraulic fluid not immediately bursting into flame in normal air? "Aerosolized mists of hydrocarbons" and "high concentrations of oxygen" are not famous for playing nicely.
Nice wide Payload fairing up there catching a lot of wind. The Pivot would likely be the upper support pads.
One issue I see with this theory is that the wind is blowing right to left (more or less) in the video. Therefore the round body of the rocket is in the lee of the TEL, thereby disrupting and partially blocking air flow to the rocket
This is not the 1st TEL flash and then fire event that was triggered by LOX coming into contact with the something on the TEL:
https://www.youtube.com/watch?v=tM-QlPAMLEc?t=62
Hit phase and then single frame it using the < & > keys.
im only counting 6 of these lines? 4 small ones, 1 medium, 1 larger?
Nice wide Payload fairing up there catching a lot of wind. The Pivot would likely be the upper support pads.
One issue I see with this theory is that the wind is blowing right to left (more or less) in the video. Therefore the round body of the rocket is in the lee of the TEL, thereby disrupting and partially blocking air flow to the rocket
Add a little resonance and who knows?
im only counting 6 of these lines? 4 small ones, 1 medium, 1 larger?
See below.
It would seem there is something going on in the centre of the fireball and that something is just above the S2 cradle and to the left of the 14 hydraulic line joints.
This is not the 1st TEL flash and then fire event that was triggered by LOX coming into contact with the something on the TEL:
https://www.youtube.com/watch?v=tM-QlPAMLEc?t=62
Hit phase and then single frame it using the < & > keys.
No, that was not LOX related. It was RP-1
That is two failures.
It would seem there is something going on in the centre of the fireball and that something is just above the S2 cradle and to the left of the 14 hydraulic line joints.
Well that's a new processing method to me. Exactly what did you do here?
im only counting 6 of these lines? 4 small ones, 1 medium, 1 larger?
See below.
This is not the 1st TEL flash and then fire event that was triggered by LOX coming into contact with the something on the TEL:
https://www.youtube.com/watch?v=tM-QlPAMLEc?t=62
Hit phase and then single frame it using the < & > keys.
No, that was not LOX related. It was RP-1
RP-1 was dumped from the top of the TEL, fell down and then ignited?
im only counting 6 of these lines? 4 small ones, 1 medium, 1 larger?
See below.
You mean gas lines
Postulating a theory that puts a load-bearing support on the strongback at a point that would push it up against the thin wall of an empty tank while it's carrying a cantilevered load of many tons would require the designers of the GSE to be nincompoops. Or worse.
Not by the standard of accident investigation. From the National Fire Protection Association (http://www.nfpa.org/Assets/files/AboutTheCodes/61/61_A2016_CMD-AGR_SD_SRStatements.pdf), " always assume an ignition source is present unless we can prove one cannot exist". So one failure (hydrauic fluid leak) and one contributing factor (should have used hydraulic fluid that is non-flammable even in high oxygen environments). Of course if SpaceX used a completely non-flammable fluid such as water, all these arguments are moot.If that was the hypothesis - again, please correct me if I'm wrong - then what's the relevance of hydraulic fluid not immediately bursting into flame in normal air? "Aerosolized mists of hydrocarbons" and "high concentrations of oxygen" are not famous for playing nicely.
That is two failures.
This is not the 1st TEL flash and then fire event that was triggered by LOX coming into contact with the something on the TEL:
https://www.youtube.com/watch?v=tM-QlPAMLEc?t=62
Hit phase and then single frame it using the < & > keys.
No, that was not LOX related. It was RP-1
RP-1 was dumped from the top of the TEL, fell down and then ignited?
From the second stage umbilical
No, I am not stating that. I am stating that you are making an assumption based on no supporting data and there are better explaination for those lines.im only counting 6 of these lines? 4 small ones, 1 medium, 1 larger?
See below.
You mean gas lines
So ALL the 7 lines are GAS lines?
SpX uses gas pressurised actuators and not hydraulic pressurised actuators on that portion of the TEL?
Postulating a theory that puts a load-bearing support on the strongback at a point that would push it up against the thin wall of an empty tank while it's carrying a cantilevered load of many tons would require the designers of the GSE to be nincompoops. Or worse.
Your words: "carrying a cantilevered load of many tons" And maybe this is the beginning of the incident. Load was expected to be spread across the TOP and bottom supports. One slight misalignment. Rocker pivot doesn't rock, who knows? Then you raise it to vertical with just six supports? Those bottom ones rather narrow? Certainly narrower than the top.
Something in this mess has to be "unthinkable". Astonishingly quick. A two part scenario.
Something strange enough that it would get past some of the smartest designers and engineers there are. So no, you have it backwards. We KNOW they would have worked the issues that make sense. That only leaves the issues that don't make sense. (with our extremely limited knowledge).
The center of the initial saturated area actually has a hole in the blue channel.
No, I am not stating that. I am stating that you are making an assumption based on no supporting data and there are better explaination for those lines.im only counting 6 of these lines? 4 small ones, 1 medium, 1 larger?
See below.
You mean gas lines
So ALL the 7 lines are GAS lines?
SpX uses gas pressurised actuators and not hydraulic pressurised actuators on that portion of the TEL?
The vehicle needs He and GN2 of different pressures and that is the likely purpose of those lines. Seven makes no sense for hydraulics.
im only counting 6 of these lines? 4 small ones, 1 medium, 1 larger?
See below.
i think what youve got marked as 6 and 7 are one large line?
1. The rocket is chock full of accelerometers. SpaceX knows how much the rocket is moving and if a resonance is occurring.Nice wide Payload fairing up there catching a lot of wind. The Pivot would likely be the upper support pads.
One issue I see with this theory is that the wind is blowing right to left (more or less) in the video. Therefore the round body of the rocket is in the lee of the TEL, thereby disrupting and partially blocking air flow to the rocket
Add a little resonance and who knows?
Not really hard to model. And it would be too short of a time frame to cause damage. The tanks fill fast. And as I posted videos, Launch vehicles do flex.
The rocket is has accelerometers. SpaceX should have actual data on how much the rocket was swaying, if it was resonating and if it smacked into the TEL. Even if they lost all telemetry on impact and the impact wasn't transmitted they should have the data showing the increasing amplitude of the "sway."Not really hard to model. And it would be too short of a time frame to cause damage. The tanks fill fast. And as I posted videos, Launch vehicles do flex.
Clearly rockets flex, not in dispute. But what about harmonics in this particular case? Are you saying engineers have never overlooked, poorly modeled, or just got harmonics wrong?
No, I am not stating that. I am stating that you are making an assumption based on no supporting data and there are better explaination for those lines.im only counting 6 of these lines? 4 small ones, 1 medium, 1 larger?
See below.
You mean gas lines
So ALL the 7 lines are GAS lines?
SpX uses gas pressurised actuators and not hydraulic pressurised actuators on that portion of the TEL?
The vehicle needs He and GN2 of different pressures and that is the likely purpose of those lines. Seven makes no sense for hydraulics.
The rocket is has accelerometers. SpaceX should have actual data on how much the rocket was swaying, if it was resonating and if it smacked into the TEL. Even if they lost all telemetry on impact and the impact wasn't transmitted they should have the data showing the increasing amplitude of the "sway."Not really hard to model. And it would be too short of a time frame to cause damage. The tanks fill fast. And as I posted videos, Launch vehicles do flex.
Clearly rockets flex, not in dispute. But what about harmonics in this particular case? Are you saying engineers have never overlooked, poorly modeled, or just got harmonics wrong?
Not really hard to model. And it would be too short of a time frame to cause damage. The tanks fill fast. And as I posted videos, Launch vehicles do flex.
Clearly rockets flex, not in dispute. But what about harmonics in this particular loading case? Are you saying engineers have never overlooked, poorly modeled, or just got harmonics wrong?
The rocket is has accelerometers. SpaceX should have actual data on how much the rocket was swaying, if it was resonating and if it smacked into the TEL. Even if they lost all telemetry on impact and the impact wasn't transmitted they should have the data showing the increasing amplitude of the "sway."Not really hard to model. And it would be too short of a time frame to cause damage. The tanks fill fast. And as I posted videos, Launch vehicles do flex.
Clearly rockets flex, not in dispute. But what about harmonics in this particular case? Are you saying engineers have never overlooked, poorly modeled, or just got harmonics wrong?
It wouldn't have to hit anything, just vibrate in just the wrong way and crack the weld at the common bulkhead.
The center of the initial saturated area actually has a hole in the blue channel.
Now a couple of other things to think about.
BLUE is going to usually be more in focus than Red or Green. Shorter wavelengths.
Also, my eyes may be deceiving me by now, but taking your thought and running with it. There is a chance that the initial shockwave is visible in the blue channel for some number of frames. Can you do your own independent magic and see if you agree, and if so, at which frame does it hit the "nearest" tower?
<snip>
I've been looking at the actual initial 'deflagation', after T=0 and found there is quite a lot to see in the Blue channel <snip>
What three devices? There are on two clamps
2. The same accelerometers would tell them if the second stage hit the pad especially with enough force to puncture a tank.
It seems unlikely to be the cause and unlikely that SpaceX would not figured it out if it was.
The center of the initial saturated area actually has a hole in the blue channel.
Now a couple of other things to think about.
BLUE is going to usually be more in focus than Red or Green. Shorter wavelengths.
Also, my eyes may be deceiving me by now, but taking your thought and running with it. There is a chance that the initial shockwave is visible in the blue channel for some number of frames. Can you do your own independent magic and see if you agree, and if so, at which frame does it hit the "nearest" tower?
This is heavily compressed video, with different ratios of data for each channel. You are reading too much into very limited data. This is the equivalent of zooming in to a highly compressed JPEG and thinking that you are seeing something that is likely just an artifact of data compression.
im only counting 6 of these lines? 4 small ones, 1 medium, 1 larger?
See below.
i think what youve got marked as 6 and 7 are one large line?
i think the left most line is also smaller than the rest.
1 small, 3 medium, 1 large, 1 X-large
you can see where the L and XL make a turn to the left. easier to see there.
edit: or maybe youre right about the right side... 1 small, 3 medium, 1 large, 1 large, 1 small
The rocket is has accelerometers. SpaceX should have actual data on how much the rocket was swaying, if it was resonating and if it smacked into the TEL. Even if they lost all telemetry on impact and the impact wasn't transmitted they should have the data showing the increasing amplitude of the "sway."
(a) At least one line should be under pressure to keep the claw closed.They are hydraulic lines that have been cut and extended. Note the 14 in line connectors at each end of the extension section. You can see them toasted in the attached. See if you can count 7 lines as in the original image.A. Why would they be under pressure at that time?
b. why would there be 7 lines for only two actuators?
c. The leak would be seen on other cameras
d. How do you know they are hydraulic lines and not He and GN2 lines?
With the exception of those comprised primarily of water, all hydraulic fluids are flammable when exposed to the proper conditions. Leaking pressurized hydraulic fluids may develop a mist or fine spray that can flash or explode upon contact with a source of ignition.
The rocket is has accelerometers. SpaceX should have actual data on how much the rocket was swaying, if it was resonating and if it smacked into the TEL. Even if they lost all telemetry on impact and the impact wasn't transmitted they should have the data showing the increasing amplitude of the "sway."
Maybe not so much "sway"ing, as much as vibrating like a tuning fork. Compressing the frost layer, into an ice/lox ridge just above the common bulkhead line. where it might be colder than expected.
(a) At least one line should be under pressure to keep the claw closed.They are hydraulic lines that have been cut and extended. Note the 14 in line connectors at each end of the extension section. You can see them toasted in the attached. See if you can count 7 lines as in the original image.A. Why would they be under pressure at that time?
b. why would there be 7 lines for only two actuators?
c. The leak would be seen on other cameras
d. How do you know they are hydraulic lines and not He and GN2 lines?
(b) and (d). There must be at least 2 hydraulic lines going to the top of the erector to run the claw. Maybe not all 7 are hydraulic.
(c) Small hydraulic leaks are well known (https://www.gates.com/~/media/files/gates/industrial/fluid-power/manuals/gates_fluid_power_ebook.pdf) for being nearly invisible, even at close range. (Often leading to injuries where the hydraulic fluid is injected into a worker's hand, even through gloves.) A quite substantial leak might take place without being seen on camera, especially as any camera viewing the back of the T/E would be fairly far away.
Leaking hydraulics are also known to cause explosions if they are not using water based fluid. From the same document:QuoteWith the exception of those comprised primarily of water, all hydraulic fluids are flammable when exposed to the proper conditions. Leaking pressurized hydraulic fluids may develop a mist or fine spray that can flash or explode upon contact with a source of ignition.
First time poster... I'm not sure if I've seen this scenario so I apologize if it's already been mentioned. The Titan II silo accident in 1980 was caused by FOD dropped down into the silo (in that case a large socket) which bounced and pierced the skin creating an aerosol. The resultant explosion took out the entire missile and silo:
http://www.encyclopediaofarkansas.net/encyclopedia/entry-detail.aspx?entryID=2543
Note that those were hypergolic propellants... In the SpaceX case, a large piece of FOD could have fallen off the strongback due to the high wind, bounced off one of the strongback beams and hit the skin of the fuel tank and created a pinhole leak. Hydrostatic pressure in the tank would be sufficient to generate an aerosol that would then mix with the vented LOX. Still need an ignition source though. Also you would think a camera would catch it but it wouldn't take much of an object to cause damage.
....
I observed a 3000 psi hydraulic leak inside a helicopter I was flying some years back, within seconds half the cabin was filled with fine foglike mist. This from a cracked fitting on a line less than 1/2 inch in diameter. Outside in bright sun and from a distance the leak would have been easy to miss.
(a) At least one line should be under pressure to keep the claw closed.
Wires "buzz" because they have a small diameter and the frequency of the vortex shedding is inversely proportional to the diameter (and proportional to the wind velocity). I'm pretty sure to get the 3.6 m F9 body or the 5.2 m fairing to buzz would require unrealistic winds. The input frequency from any wind that would actually exist at ground level would induce a sway, not a buzz. And a buzz would imply tiny movements anyway.
The rocket is has accelerometers. SpaceX should have actual data on how much the rocket was swaying, if it was resonating and if it smacked into the TEL. Even if they lost all telemetry on impact and the impact wasn't transmitted they should have the data showing the increasing amplitude of the "sway."
Maybe not so much "sway"ing, as much as vibrating like a tuning fork. Compressing the frost layer, into an ice/lox ridge just above the common bulkhead line. where it might be colder than expected.
Followup: I think there's good evidence that it was interlaced, but that the interlacing has been filtered out. See this:
https://c7.staticflickr.com/9/8324/29619459086_d5c8623e19_z.jpg
(https://c7.staticflickr.com/9/8324/29619459086_d5c8623e19_z.jpg)
That's from the highest res video I could download from Youtube, 1080p mp4. Odd lines on the top, even lines on the bottom, split with:
ffmpeg -ss 71 -i video.mp4 -t 1 -vf il=d out-%04d.png
Note that halfway through the odd lines there suddenly starts a chromatic abberation, which slowly diminishes as it continues downward. The abberation continues along the even frames, top to bottom. Yet the "image" in both the even and odd rows is identical. It seems quite likely that the video was initially interlaced but has subsequently been deinterlaced during processing. If so then there would be an additional recoverable frame as well as highly precise (sub-millisecond) timing on when the explosion began and at least the X coordinate in the frame of the ignition point.
If the original wasn't interlaced, I'd expect that the images from the even and odd rows would look almost identical. They don't. I can't think of a way that this result could be explained by compression artifacts, either.
Someone earlier suggested that the 1080 was upsampled from the original of 720. That might do it.
Do you see the same on the 720 version?
The center of the initial saturated area actually has a hole in the blue channel.
Now a couple of other things to think about.
BLUE is going to usually be more in focus than Red or Green. Shorter wavelengths.
Also, my eyes may be deceiving me by now, but taking your thought and running with it. There is a chance that the initial shockwave is visible in the blue channel for some number of frames. Can you do your own independent magic and see if you agree, and if so, at which frame does it hit the "nearest" tower?
This is heavily compressed video, with different ratios of data for each channel. You are reading too much into very limited data. This is the equivalent of zooming in to a highly compressed JPEG and thinking that you are seeing something that is likely just an artifact of data compression.
:) I think not. :) I really kinda sorta know what a compression artifact is. I was using wavelets to reduce artifacts long before most of you folks ever heard of GIF files. I have a colleague who was on the committee that drafted the first JPEG standard and she was simply appalled that the industry took the example in the appendix and defined it as the standard. JPEG does not have to create the types of artifacts we all know & love. The appendix example, however, does, and hence that's our standard these days.
The center of the initial saturated area actually has a hole in the blue channel.
Now a couple of other things to think about.
BLUE is going to usually be more in focus than Red or Green. Shorter wavelengths.
Also, my eyes may be deceiving me by now, but taking your thought and running with it. There is a chance that the initial shockwave is visible in the blue channel for some number of frames. Can you do your own independent magic and see if you agree, and if so, at which frame does it hit the "nearest" tower?
This is heavily compressed video, with different ratios of data for each channel. You are reading too much into very limited data. This is the equivalent of zooming in to a highly compressed JPEG and thinking that you are seeing something that is likely just an artifact of data compression.
:) I think not. :) I really kinda sorta know what a compression artifact is. I was using wavelets to reduce artifacts long before most of you folks ever heard of GIF files. I have a colleague who was on the committee that drafted the first JPEG standard and she was simply appalled that the industry took the example in the appendix and defined it as the standard. JPEG does not have to create the types of artifacts we all know & love. The appendix example, however, does, and hence that's our standard these days.
H264, which I suspect this was recorded with, doesn't use wavelets.
And the sensor in the camera will record all three colour channels at the same time, blue won't be 'earlier'. Note the CCD's are in effect black and white, and there is a RGB bayer filter that cuts out unwanted colours for each pixel. There are twice as many green pixels as red or blue, so green is a better channel for detail, if the bayer data (raw) were available. Once it's debayered, and all the image processing pipeline has had its evil way, the individual pixels are entirely untrustworthy. Debayering (depending on the algorithm) causes fringing, the slightest movement of either the camera or the subject is likely to cause weird fringing changes at the pixel level. Don't trust them.
There is a cloud at the bottom right of the fireball that seems to grow over the first few frames. No surprise.Sorry, I can't get what you're pointing at? Can you annotate the image?
However, if this is condensed water vapor or LOX or GOX, just where the heck did it come from so early in this sequence?
There is a cloud at the bottom right of the fireball that seems to grow over the first few frames. No surprise.Sorry, I can't get what you're pointing at? Can you annotate the image?
However, if this is condensed water vapor or LOX or GOX, just where the heck did it come from so early in this sequence?
I think if you look at frame 2 and 3 in the blue (where vapor was formed), you can get a rough idea how the initial deflagation developed. With that in mind, i think we're able to see what part of the frame 1 flash (frame 0 being the intact f9) is the light reflected off the f9/tel and what not. For me, it looks like it never extended up to the fairings, neither below the interstage.
But it MIGHT have deformed it just enough to get the pad stuck while it was trying to slide. Ice/LOX dam? As Jim stated, it MUST slide.
Say one side sticks but not the other, Could that develop enough force to snap a turnbuckle support? That snapping could be the flash. If at the top connector, it may have forced the turnbuckle towards the tank wall and THAT's what punctured the tank.
(trimmed)
I'm well aware of how camera technology compromises imaging.
Depending on the compression employed, i.e. best basis wavelets, pixels are not inherently untrustworthy, depends on how much compression you really need.
Commercial camera products? I would say that any 16x16 jpeg block is a reasonable representation of what was in that block, and the pixels themselves may be ok if there's no contrast in the block... sometimes.
<snip>
I've been looking at the actual initial 'deflagation', after T=0 and found there is quite a lot to see in the Blue channel <snip>
Given the choice of red pill or blue, the blue is the better choice.
Thought I'd look at what you're looking at and see if there was anything interesting.
There is something rather bizarre here, attached animated gif, I think.
There is a cloud at the bottom right of the fireball that seems to grow over the first few frames. No surprise.
However, if this is condensed water vapor or LOX or GOX, just where the heck did it come from so early in this sequence?
The camera most likely didn't have a ccd but a close detector. Not impossible that it's ccd but extremely rare in commercial cameras. Also absorption of oxygen is narrow band, the light source is broad band, like the pixel filter. Oxygen absorption is not enough to make a difference. However most glasses have less throughout in blue than in red or green. Might be the reason why blue is less overexposed. Pure speculation here though.
Ohh autocorrection on mobile phone... I meant cmos. Sorry. I correct the post.
Can someone explain from Frame 0 [pre-explosion] to frame1 how the tongue of flame that extends downward and around the S1 section of the Falcon. it is not just a reflection and can not be RP-1 in a few milliseconds. The GIF sequence demonstrates that in frames 2-3-4 the expansion of the fireball and the discontinuation of the tongue extending down the stage.
Is it possible that the initiation event occurred down below the Grid-Fins and traveled up to the location of the venting GOX on the S2? I can't account for the long section of flame below the point of explosion at the middle bumper common bulkhead section. watching this GIF cycle to me it looks similar to re-lighting a candle by igniting the fumes from the wick as shown here.
https://www.youtube.com/watch?v=C5eTn5d0cvg (https://www.youtube.com/watch?v=C5eTn5d0cvg)
Are you still using video sourced from YouTube? Wouldn't it have been transcoded at least one additional time after the camera's initial encoding, with unknown settings?
Add in the fact that there is only one source in the public domain, and it gets much more difficult to extract anything with confidence (ie, are you seeing a deceptive lighting effect that, while not an artifact, wouldn't show up from a different angle)
sigh
Even if we are limited to a single horribly destroyed youtube video
The camera most likely didn't have a ccd but a cmos detector. Not impossible that it's ccd but extremely rare in commercial cameras. Also absorption of oxygen is narrow band, the light source is broad band, like the pixel filter. Oxygen absorption is not enough to make a difference. However most glasses have less throughout in blue than in red or green. Might be the reason why blue is less overexposed. Pure speculation here though.
Are you still using video sourced from YouTube? Wouldn't it have been transcoded at least one additional time after the camera's initial encoding, with unknown settings?
Add in the fact that there is only one source in the public domain, and it gets much more difficult to extract anything with confidence (ie, are you seeing a deceptive lighting effect that, while not an artifact, wouldn't show up from a different angle)
sigh
You are sighing because you've already answered this multiple times, or because it's an exceedingly stupid question? I've generally kept up with the thread from the beginning, but when it grows 5 pages in the course of an evening out, it's impossible to keep up with everything.
Please help me out with a pointer. I've searched and not found it.
Yes, the vehicle can flex, but the lower pad can't. That's the problem, if the vehicle flexes towards it, the pad will puncture the fuselage.
The "lower pad" rests on a visibly-reinforced portion of S2 right where the common bulkhead exists inside the stage. It's probably the strongest portion of S2 aside from the thrust structure at the bottom of the RP1 tank. I've made this point several times over the last two weeks, but rockets just aren't that fragile and the designers aren't complete nincompoops when it comes to designing their support equipment.
if the vehicle flexes towards it, the pad will puncture the fuselage.
No, it won't. It is not point load, it is spread out by the pad. And it is at the common bulkhead joint and not a tank side.
Are you still using video sourced from YouTube? Wouldn't it have been transcoded at least one additional time after the camera's initial encoding, with unknown settings?
Add in the fact that there is only one source in the public domain, and it gets much more difficult to extract anything with confidence (ie, are you seeing a deceptive lighting effect that, while not an artifact, wouldn't show up from a different angle)
sigh
You are sighing because you've already answered this multiple times, or because it's an exceedingly stupid question? I've generally kept up with the thread from the beginning, but when it grows 5 pages in the course of an evening out, it's impossible to keep up with everything.
Please help me out with a pointer. I've searched and not found it.
I'm sorry, it's been a long week. I apologize if that was interpreted in a demeaning way.
Absolutely the video was transcoded too many ways, from the CCD, to the ADC, to the MPEG DSP, to the actual recording, and then from the actual recording to youtube. Lord knows how many bits flipped along the way, plus if it was a CPD instead of a CCD things would have been even stranger.
Yes, you're absolutely right that the image content on the youtube video is like, difficult.
As for extracting things with confidence, in spite of all of that butchering of the raw data, the techniques I and others have applied actually can find a degree of real content in the video. Unfortunately, any video analysis that relies on the value of a single pixel, or in this case, a range of 16x16 pixels, is suspect.
The astrophotography techniques after atmospheric correction techniques are supposed to bring us to the diffraction limit of the lens, but in a recent video posted here, which is as good as it gets, we're still on the order of 1 pixel +- 6.
That's really bad. Kinda like we have about 3 foot resolution when we think we see 6 inch resolution.
The sigh was based on the fact that I know exactly what I'm dealing with, and you only identified a small subset of the problems, which are sadly, 1/3 of the ones I'm trying to deal with in my processing models.
I apologize for my brief comment. Yours was valid, and I was sighing because it's not only valid, but you missed some of the issues as well.
The simple fact is, that video is all we have, and it sucks, and it takes a lot of work to jam every possible bit back to where it belongs, and that, sigh, will never happen with that video.
... and we need to take into account the effect of the release of latent heat by the LOX as it condenses (if it does).
You also need to take into account the effect of the release of latent heat by the water that is also freezing out.
Hence...My point here is that the release of latent heat of condensation will act like a thermostat [...]
...by your own argument, the external temperature of the skin cannot ever fall below 77K. Water vapour in that humid Florida wind will act like a thermometer, continually raising the temperature until the rate of ice formation slows.This would still be very localized when a few milliseconds later it has burnt through the tank wall [...]
A few milliseconds? Of a solid aluminium fire?1. The outside of the tank must be far enough below 90K to prevent condensing LOx from evaporating.Technically, it's condensing faster than it's evaporating. This is know to happen with LN2 (see references). The outside is colder than LN2 (see calculations).
Much earlier in the thread, several people modelled the flow of heat and showed that the external temperature wouldn't fall below the critical 77K. Even the smallest amount of water-ice frost will prevent LOx condensation, even ignoring the heat of condensation of that frost.
Hence someone else (I'm too lazy to go hunting) suggested that the frost itself would insulate the skin, allowing the skin to subcool under the ice, if the ice fell away, it would briefly expose sub-77K skin to the air.
That led to the suggestion that the cradle pads could have scraped away the ice as the vehicle condensed, which led to the idea that the pads themselves (soaked in LOx) could have also provided the fuel for the initial blast.
My response was to try to show the failure to think through the contradictions in that idea. Amongst other things, if the pads scrape the ice away from the tank, exposing skin below the pads to allow LOx condensation, how did the pads become "soaked" in the LOx that is forming below them?
You also need to take into account the effect of the release of latent heat by the water that is also freezing out. ...by your own argument, the external temperature of the skin cannot ever fall below 77K. Water vapour in that humid Florida wind will act like a thermometer, continually raising the temperature until the rate of ice formation slows.Surely 273 K? But yes, the outside of the frost layer will never go below 273 K in humid air for that reason. If the rocket cools, and the outside of the frost cools with it, more water vapour will freeze onto the outside of the frost layer, warming it and thickening it (insulating the rocket better) until a new equilibrium is reached with a colder rocket and a thicker frost blanket. But all this happens on the outside of the frost, while the LOX condensation happens (if it does) on the inside next to the paint, which is why the LOX-frost theory relies on the frost having enough air-spaces inside it to allow O2 to diffuse in as far as the paint.
The outside of the tank must be far enough below 90K to prevent condensing LOx from evaporating.True. The limiting temperature is 77 K, at which the vapour pressure of LOX equals 20 kPa, the partial pressure of O2 in the atmosphere. (It's pure coincidence that this is also the boiling point of LN2.)
Much earlier in the thread, several people modelled the flow of heat and showed that the external temperature wouldn't fall below the critical 77K.If you mean LouScheffer at #2694, he wasn't taking the frost into account.
Even the smallest amount of water-ice frost will prevent LOx condensation, even ignoring the heat of condensation of that frost.This isn't true if O2 can diffuse in through the frost. Of course if the "frost" is a continuous layer of glassy ice, the outside of it will be at 273 K (for the reason above), and you'd be right, LOX condensation couldn't happen (and you'd have to knock or scrape the ice off to expose a sub-77 surface to the air). But the frost that forms on cryo equipment is not glassy flawless ice. It's more like compacted dry snow, and is very far from airtight.
Hence someone else (I'm too lazy to go hunting) suggested that the frost itself would insulate the skin, allowing the skin to subcool under the iceThat might have been me, among others. My analysis of the thermal gradients and heat flows is here:
It's long. Click on the link to see it.
That led to the suggestion that the cradle pads could have scraped away the ice as the vehicle condensed, which led to the idea that the pads themselves (soaked in LOx) could have also provided the fuel for the initial blast.I think the cradle-pads are irrelevant. No scraping is necessary to make the LOX, and there is a much better source of fuel right next to the LOX; the Al tank-wall, only the paint-thickness away.
First time poster... I'm not sure if I've seen this scenario so I apologize if it's already been mentioned. The Titan II silo accident in 1980 was caused by FOD dropped down into the silo (in that case a large socket) which bounced and pierced the skin creating an aerosol. The resultant explosion took out the entire missile and silo:
http://www.encyclopediaofarkansas.net/encyclopedia/entry-detail.aspx?entryID=2543
Note that those were hypergolic propellants... In the SpaceX case, a large piece of FOD could have fallen off the strongback due to the high wind, bounced off one of the strongback beams and hit the skin of the fuel tank and created a pinhole leak. Hydrostatic pressure in the tank would be sufficient to generate an aerosol that would then mix with the vented LOX. Still need an ignition source though. Also you would think a camera would catch it but it wouldn't take much of an object to cause damage.
The puncture in the Titan didn't aerosolize the hypergolics. The socket punctures the skin of the stage (Titan II was a balloon). The hypergolic poured out of the stage for some time (there were, IIRC, two attempts to enter the silo and stop the leakage). The hypergolics ended up pooling in the bottom of the silo and when the stage lost structure due to loss of pressure, the collapse burst the other hypergolic tank and you had a explosive mix in the bottom of the silo - essentially a cannon shot that blew the blast doors off the silo and the warhead quite some distance away.
Reference - Command and Control: Nuclear Weapons, the Damascus Accident, and the Illusion of Safety, Eric Schlosser
Edit: misspelling
This obviously isn't the exact same scenario as the SpaceX situation but my only point is that a small skin puncture can create an vapor cloud.
Of course if the "frost" is a continuous layer of glassy ice, the outside of it will be at 273 K (for the reason above), and you'd be right, LOX condensation couldn't happen
If one of these bits of organic matter does act as an initiator and ignite with the LOX,
This obviously isn't the exact same scenario as the SpaceX situation but my only point is that a small skin puncture can create an vapor cloud.
Still not applicable analogy. RP-1 doesn't form a vapor cloud
This obviously isn't the exact same scenario as the SpaceX situation but my only point is that a small skin puncture can create an vapor cloud.
Still not applicable analogy. RP-1 doesn't form a vapor cloud
But can it create an aerosol cloud ?
I found an interesting Air Force Propulsion Laboratory document (http://dtic.mil/dtic/tr/fulltext/u2/665121.pdf) describing the fire, detonation, and autoignition criteria of various hydraulic fluid mists, including dependency on GOX concentration. Page 55 shows an especially interesting graph. Mineral oil mists (the most common hydraulic fluid) are very flammable at oxygen partial pressures > 0.3 atm, but the autoignition temperatures are off the bottom of the graph and it's not possible to extrapolate whether it could spontaneously ignite or still need an initiator.
I would propose setting up a shared google doc, wiki or similar colaboration page so we could collect together each theory , why they would be plausible, and what speaks against them. Reading back in this thread is becoming increasingly unfeasible, especially as arguments pop up repeatedly and you try to find a previous answer in the hundreds of pages. We had some real gemstones of posts but you need to dig deeply.
As it gets harder to keep oversight were running in circles
Elon may call this a fast fire, but, IMHO an event that obliterates a 35 X 85 foot area in 16 milliseconds, which is my best estimate, to me is defined as a detonation (others disagree)
PS. I'm quite sure SpaceX knows by now WHAT happened. They may not know exactly WHY it happened..
QuoteEven the smallest amount of water-ice frost will prevent LOx condensation, even ignoring the heat of condensation of that frost.
This isn't true if O2 can diffuse in through the frost. Of course if the "frost" is a continuous layer of glassy ice, the outside of it will be at 273 K (for the reason above), and you'd be right, LOX condensation couldn't happen (and you'd have to knock or scrape the ice off to expose a sub-77 surface to the air). But the frost that forms on cryo equipment is not glassy flawless ice. It's more like compacted dry snow, and is very far from airtight.
Good effort, your earned a break while we all wait! :)
Are you still using video sourced from YouTube? Wouldn't it have been transcoded at least one additional time after the camera's initial encoding, with unknown settings?
Add in the fact that there is only one source in the public domain, and it gets much more difficult to extract anything with confidence (ie, are you seeing a deceptive lighting effect that, while not an artifact, wouldn't show up from a different angle)
sigh
You are sighing because you've already answered this multiple times, or because it's an exceedingly stupid question? I've generally kept up with the thread from the beginning, but when it grows 5 pages in the course of an evening out, it's impossible to keep up with everything.
Please help me out with a pointer. I've searched and not found it.
I'm sorry, it's been a long week. I apologize if that was interpreted in a demeaning way.
Absolutely the video was transcoded too many ways, from the CCD, to the ADC, to the MPEG DSP, to the actual recording, and then from the actual recording to youtube. Lord knows how many bits flipped along the way, plus if it was a CPD instead of a CCD things would have been even stranger.
Yes, you're absolutely right that the image content on the youtube video is like, difficult.
As for extracting things with confidence, in spite of all of that butchering of the raw data, the techniques I and others have applied actually can find a degree of real content in the video. Unfortunately, any video analysis that relies on the value of a single pixel, or in this case, a range of 16x16 pixels, is suspect.
The astrophotography techniques after atmospheric correction techniques are supposed to bring us to the diffraction limit of the lens, but in a recent video posted here, which is as good as it gets, we're still on the order of 1 pixel +- 6.
That's really bad. Kinda like we have about 3 foot resolution when we think we see 6 inch resolution.
The sigh was based on the fact that I know exactly what I'm dealing with, and you only identified a small subset of the problems, which are sadly, 1/3 of the ones I'm trying to deal with in my processing models.
I apologize for my brief comment. Yours was valid, and I was sighing because it's not only valid, but you missed some of the issues as well.
The simple fact is, that video is all we have, and it sucks, and it takes a lot of work to jam every possible bit back to where it belongs, and that, sigh, will never happen with that video.
Of course if the "frost" is a continuous layer of glassy ice, the outside of it will be at 273 K (for the reason above), and you'd be right, LOX condensation couldn't happen
And it doesn't, that is the reality. There have been past missions with higher and lower humidity.If one of these bits of organic matter does act as an initiator and ignite with the LOX,
And this fails. The organic matter is the fuel, there still has to be initiator to cause ignition. Just sitting there does not make it burn. Thumb prints only burned when impacted
This is why I don't think your first point is sound. The fact that they haven't blown up before may have been just good luck, the absence of an initiator. For all we know, they may all have had LOX-frost and organic matter - how would we see that from outside? And would it show up in telemetry?
PS. I'm quite sure SpaceX knows by now WHAT happened. They may not know exactly WHY it happened..
Last information from Shotwell was, that they didn't even know, whether it was the F9 or something else. This was on 09/13.
...
The simple fact is, that video is all we have, and it sucks, and it takes a lot of work to jam every possible bit back to where it belongs, and that, sigh, will never happen with that video.
It's great that you did that, but I recall Chris saying something about organizing something through NSF membership. Perhaps he can update us! :)...
The simple fact is, that video is all we have, and it sucks, and it takes a lot of work to jam every possible bit back to where it belongs, and that, sigh, will never happen with that video.
USLaunchReport accepts support over at their youtube channel. I made a donation along with a request to share the original video recording with the NSF community.
If the original video file would be useful, I suggest a concerted effort by NSF members to provide support to them and echo the request for the video.
The youtube channel is here: https://www.youtube.com/channel/UC5hWqb0u1eKgYmVryCEyJYA/featured
It's great that you did that, but I recall Chris saying something about organizing something through NSF membership. Perhaps he can update us! :)...
The simple fact is, that video is all we have, and it sucks, and it takes a lot of work to jam every possible bit back to where it belongs, and that, sigh, will never happen with that video.
USLaunchReport accepts support over at their youtube channel. I made a donation along with a request to share the original video recording with the NSF community.
If the original video file would be useful, I suggest a concerted effort by NSF members to provide support to them and echo the request for the video.
The youtube channel is here: https://www.youtube.com/channel/UC5hWqb0u1eKgYmVryCEyJYA/featured
I think "not affecting the rates" is just a combination of two things: 1) the failure rate still matches the insurance companies' internal estimate of falcon failure rates---which may be higher than spacex thinks it should be, but the insurance adjusters are saying they've done a good job, and 2) the launch insurance didn't actually pay out on this incident---reports are that the "marine transport insurance" was on the hook, since the cargo hadn't "launched" yet.PS. I'm quite sure SpaceX knows by now WHAT happened. They may not know exactly WHY it happened..
Last information from Shotwell was, that they didn't even know, whether it was the F9 or something else. This was on 09/13.
But she said this incident doesn't affect the insurance rates for F9 launches. Maybe I'm jumping to conclusions but I think that means there's nothing wrong with the launch vehicle. (Also, the "anomaly" didn't really seem to initiate from within the rocket.)
So, for flex induced by vortex shedding from the fairing to be a significant issue, here are some of the pre-conditions:
1. The payload and fairing are attached.
2. The wind speed is 9.8m/s.
3. The grabber is closed.
4. The fuel load is such that the natural frequency matches the shedding forces.
5. The position of the grabbers matches the node of the mode shape.
6. The cradle (and hence the lower pad) is fixed in position by the grabber and the pin joint on the strongback, which is vastly stiffer and stronger than the rocket.
So, for the fairing, shedding leads to forces oscillating at 0.177 and 0.354 Hz.By your own math, it would take *at least* three seconds to reach maximum deflection. That's order of magnitudes slower than the event is seen to develop, and would be incredibly obvious from the accelerometer data on the stage.
[...]
If all of the conditions were met, the onset of a significant flex could be quite sudden, and may not register on accelerometers as anything other than a step function at the same time as the start of the fast fire.
Seriously? All you folks hanging your hats on "LOX frost" need to get a grip on reality. Even rocket is touched by technicians during servicing and close-out, they have bugs land on them, birds poop on them, they fly through clouds of insects on ascent ... This is simply not a serious issue.
This is why I don't think your first point is sound. The fact that they haven't blown up before may have been just good luck, the absence of an initiator. For all we know, they may all have had LOX-frost and organic matter - how would we see that from outside? And would it show up in telemetry?
Seriously? All you folks hanging your hats on "LOX frost" need to get a grip on reality. Even rocket is touched by technicians during servicing and close-out, they have bugs land on them, birds poop on them, they fly through clouds of insects on ascent ... This is simply not a serious issue.
Is there another option?
Is there another option?
A plumbing failure in the high pressure helium supply, as Herb and Jim have been repeatedly suggesting.
Folks with far fetched theories need to judge them by that bar. Your theory needs to be likely than, "a helium line fractured and sent a high energy fragment through the stage".
Now, that's not to say that theory is certain, and it would take a lot of work to *prove* exactly what happened to the satisfaction of the FAA, customers, NASA, etc. But IMNSHO that theory should be the "reasonableness" threshold by which other theories are judged.
"For all we know, they may all have had LOX-frost - how would we see that from outside?
No. This search for unicorns is maddening.Is there another option?
A plumbing failure in the high pressure helium supply, as Herb and Jim have been repeatedly suggesting.
Folks with far fetched theories need to judge them by that bar. Your theory needs to be likely than, "a helium line fractured and sent a high energy fragment through the stage".
Now, that's not to say that theory is certain, and it would take a lot of work to *prove* exactly what happened to the satisfaction of the FAA, customers, NASA, etc. But IMNSHO that theory should be the "reasonableness" threshold by which other theories are judged.
Trouble is, a helium line break should show up clearly in telemetry. Even if the cause of the break is much more tricky to figure out, the fact of the break initiating the failure should be broadly evident, not something Elon Musk would describe as "the most difficult and complex failure we have ever had in 14 years."
So the cause should be something "difficult and complex." It follows from what we know this isn't something relatively straightforward.
Trouble is, a helium line break should show up clearly in telemetry. Even if the cause of the break is much more tricky to figure out, the fact of the break initiating the failure should be broadly evident, not something Elon Musk would describe as "the most difficult and complex failure we have ever had in 14 years."
So we're agreed that all rockets have miscellaneous organic matter on their outside paintwork. It just never mattered before, because no rocket before F9 FT ever subcooled below 77 K.
"For all we know, they may all have had LOX-frost - how would we see that from outside?
Is there another option?
A plumbing failure in the high pressure helium supply, as Herb and Jim have been repeatedly suggesting.
Folks with far fetched theories need to judge them by that bar. Your theory needs to be at least as likely than "a helium line fractured and sent a high energy fragment through the stage".
Now, that's not to say that theory is certain, and it would take a lot of work to *prove* exactly what happened to the satisfaction of the FAA, customers, NASA, etc. But IMNSHO that theory should be the "reasonableness" threshold by which other theories are judged.
This was a most unusual incident. Nothing like it in 50 years, in any other rocket. What's new about the F9 FT design? LOX subcooled below 77 K.
On the other hand, isn't helium plumbing quite well understood and reliable in general?
1. The footage that "we" have. Since SLC asked about how would "we" see it. If you have something that's not blurry and zoomed in that you can share with the forum, I'm sure it would be greatly appreciated :)
2. Indeed it was - visible for miles and miles away.
3. I don't think people seeing a massive fireball erupt is in doubt here. You seem to be positing a slow burn triggering a far larger one. Is LOX famous for slow burns?
On the other hand, isn't helium plumbing quite well understood and reliable in general?
It's worth noting here that if this is a helium issue, it wouldn't be the first one for SpaceX, and NASA wasn't entirely satisfied with their investigation of the previous COPV failure on CRS-7. This wouldn't be that unprecedented. That's why I think it's the best current theory. It explains why there was no visible ignition on the tapes, explains the location, and has precedent within this launch vehicle's own history.
Gwynne Shotwell said: "We still haven't isolated the cause or whether its origin was rocket or ground."
I just can't believe that a failure in the helium system (COPV or pipes) would be so hard to find. Not the root cause, just "This thingamajig blew up." or even "Something blew up inside the vehicle".
Does anyone know the routing of the helium load lines from the umbilical connector to the COPVs? Do they run up the outside of the fuel and LOX tanks, then enter the LOX tank near the COPVs? Or do they run through the LOX center feed line through the fuel tank?
Does the LOX for engine chill-down come from the LOX tank or is it supplied directly from GSE?
I would like to plead, that these frost theories be kept, but not here, instead in the wacky theory thread.
Now that's interesting. The trajectory of one of the debris passes right through the object containing the delta pixel identified on my previous post.Do you know the time between when the pixel change occurred and when the object was at that point?
To Jim's point - Damaging foam was not a "real thing" IN PEOPLES MINDS until it was. LOX infused frost may not be a real thing IN PEOPLES MINDS right now. Proof Later? Likely not. But to be so dismissive?
Relax.
Now that's interesting. The trajectory of one of the debris passes right through the object containing the delta pixel identified on my previous post.Do you know the time between when the pixel change occurred and when the object was at that point?
To Jim's point - Damaging foam was not a "real thing" IN PEOPLES MINDS until it was. LOX infused frost may not be a real thing IN PEOPLES MINDS right now. Proof Later? Likely not. But to be so dismissive?
Relax.
Wrong, there is no correlation with Columbia foam and nonexistent LOX. There was evidence ignored in Columbia. There is no such evidence in this case.
LOX infused frost has just as much evidence as lone gunman, a small ordnance device, and many other things.
To Jim's point - Damaging foam was not a "real thing" IN PEOPLES MINDS until it was. LOX infused frost may not be a real thing IN PEOPLES MINDS right now. Proof Later? Likely not. But to be so dismissive?
Relax.
Wrong, there is no correlation with Columbia foam and nonexistent LOX. There was evidence ignored in Columbia. There is no such evidence in this case.
LOX infused frost has just as much evidence as lone gunman, a small ordnance device, and many other things.
Yet you seem unable to refute it. Where's your calculations that show LOX buildup cannot occur?
It's great that you did that, but I recall Chris saying something about organizing something through NSF membership. Perhaps he can update us! :)...
The simple fact is, that video is all we have, and it sucks, and it takes a lot of work to jam every possible bit back to where it belongs, and that, sigh, will never happen with that video.
USLaunchReport accepts support over at their youtube channel. I made a donation along with a request to share the original video recording with the NSF community.
If the original video file would be useful, I suggest a concerted effort by NSF members to provide support to them and echo the request for the video.
The youtube channel is here: https://www.youtube.com/channel/UC5hWqb0u1eKgYmVryCEyJYA/featured
I got tired of waiting around for Chris 8) Plus they are worth supporting anyway, they do a great job with getting videos that nobody else publishes.
I cant find the post right now but it said helium line rupture fits the location.
I can't see how an external helium line fits the location of the event.
One last thought on the rocket swaying or vibrating theory. The more I think about it, the less I like this idea anyway. But with that being said the logic used here to shoot it down was that accelerometers would have seen it, and SpaceX would have said so. And that rockets flex, and are designed to do so, etc. Yes, clearly. So the sway/vibration was seen, SpaceX though it was within tolerance (maybe on the high side, maybe not) so it doesn't raise any flags. But what if their tolerances were dead wrong. Or what if tolerances stacked up in such a way between the TEL and Rocket, or something that was supposed to move or vice versa unexpectedly failed, such that "normal/acceptable" movements now became an issue?
One last thought on the rocket swaying or vibrating theory. The more I think about it, the less I like this idea anyway. But with that being said the logic used here to shoot it down was that accelerometers would have seen it, and SpaceX would have said so. And that rockets flex, and are designed to do so, etc. Yes, clearly. So the sway/vibration was seen, SpaceX though it was within tolerance (maybe on the high side, maybe not) so it doesn't raise any flags. But what if their tolerances were dead wrong. Or what if tolerances stacked up in such a way between the TEL and Rocket, or something that was supposed to move or vice versa unexpectedly failed, such that "normal/acceptable" movements now became an issue?
It would be visible in pad videos. Did you see the onboard camera view of the rocket flexing? The flex was on the order of feet and not inches and the vehicle skin crinkled and uncrinkled.
Ever heard of the term rate gyro package on launch vehicles? Not those in the main guidance system but a package installed on the side of the booster (can't be interior because the location is usually on a prop tank). What this package does is measure the attitude and rates of the vehicle at that location which the guidance system compares with its gyros at its location. They are different because the vehicle flexes from wind and thrust vehicle control. The guidance system uses this information to adjust the control gains, so that it doesn't chase its tail all over the sky.
What if their tolerances are wrong?
What if their tolerances are wrong?
Did you see the flex video?
During the development of launch vehicles, there are structural tests that verify that the vehicle can take the loads it will see. And one of the reasons for flight instrumentation is to make sure the loads are within limits.
Read the additional paragraph to the original post.
Wouldn't these same sensors (along with the He pressure gauges) also pick up a failure in the He system.
Wouldn't these same sensors (along with the He pressure gauges) also pick up a failure in the He system.
Structural failures have signatures and are not that quick. Movement and strains can be seen before a failure.
1. Was that flex test done wile a partial load of sub cooled LOX was being loaded in a strong wind? By the way I have not seen any reports of the actual wind speed direction or speed or how that relates to past experience and launch/tanking go-no go conditions. Apologies if I missed that.
2. Could you please lay out your hypothesis (you have mentioned the He system multiple times) for this failure and please include why that would not come up in testing, or show up in telemetry.
Bursts (which are not the same as structure failures) can happen faster
Wouldn't these same sensors (along with the He pressure gauges) also pick up a failure in the He system.
Structural failures have signatures and are not that quick. Movement and strains can be seen before a failure.
Yes, clearly. So why haven't they pin pointed the failure yet?
1. Was that flex test done wile a partial load of sub cooled LOX was being loaded in a strong wind? By the way I have not seen any reports of the actual wind speed direction or speed or how that relates to past experience and launch/tanking go-no go conditions. Apologies if I missed that.
2. Could you please lay out your hypothesis (you have mentioned the He system multiple times) for this failure and please include why that would not come up in testing, or show up in telemetry.
1. It is not needed.
a. Vortex shedding was shown to be a low frequency for this vehicle. Hence, the movement that would cause loads that would cause parts to fail would be visible many ways.
b. The propellant level and temp have no bearing on the matter.
2. At the beginning, I just said it was likely related to some kind of pressure event. Later I may have said even more likely in the helium system. I am only going by the event and not providing a timeline.
By the imagery available, it happen by the strong back and that is also where the stage wiring/tubing tunnel and umbilical are located.
So temperature and fluid/pressure damping/stiffinging have no effects on rockets?
What pressure event would not have been picked up by the rocket's telemetry? And how would such a pressure event be catastrophic happening internal to a partially filled vessel?
So temperature and fluid/pressure damping/stiffinging have no effects on rockets?
What pressure event would not have been picked up by the rocket's telemetry? And how would such a pressure event be catastrophic happening internal to a partially filled vessel?
The problem with arguments like this is you have to justify why they only affect the Falcon 9 when they should otherwise be equal factors in literally dozens of other launch vehicles that have never experienced this kind of failure.
What pressure event would not have been picked up by the rocket's telemetry?
So temperature and fluid/pressure damping/stiffinging have no effects on rockets?
They do affect everything. But perhaps SpaceX missed an off nominal corner case in their analysis.
What pressure event would not have been picked up by the rocket's telemetry?
Let's be clear: We don't know what has and has not been picked up by the rocket's telemetry. That's the biggest reason that a lot of these failure analysis threads end up with conclusions that miss the mark by a wide margin when the investigation results are released--we (obviously) don't have as much info as those inside the actual investigation. Based on Musk and Shotwell's statements, some people assume that there's no sign of pressure problems on the telemetry, but neither of them have ever said that.
They do affect everything. But perhaps SpaceX missed an off nominal corner case in their analysis.
There is no corner case here
They do affect everything. But perhaps SpaceX missed an off nominal corner case in their analysis.
There is no corner case here
So there was no pad anomaly then, clearly.
I'm going to bow out now and just watch again for a while
They do affect everything. But perhaps SpaceX missed an off nominal corner case in their analysis.
There is no corner case here
So there was no pad anomaly then, clearly.
I'm going to bow out now and just watch again for a while
There are other corner cases in other places.
But explain how there can be a corner case in your example. How is the vehicle's response to exterior forces is not enveloped by the prelaunch empty and full cases. And in-flight full and empty cases where the vehicle sees loads much greater than any prelaunch
Two glaring examples of differences between flight and pad operations. A giant clamp a few meters above the apparent failure, and a support pad right at the apparent failure
OK, After staying well away form this thread I'll wander in with a question and a bit of discussion.I asked a similar question about the customer supplied harness and if that was the case in this test...
Question- Is the payload powered up at around the time in the hotfire when this event happened?
Background about the question: One item that is unique for every launch of every rocket is the wire harnesses from S2 or fairing down the pad. They are unique at each launch because the harnesses are destroyed on launch, and because each payload is different from the others.
On other launchers with payloads that I've worked, we check those harnesses out long before day of launch (and in fact do checks of those things way before we ever get to the pad).
The flow with a F9 launch compresses those timelines greatly. What happens if there was an undetected wiring error in those harnesses? In my view this opens up a bunch of branches in the fault tree. Aside from providing potential ignition sources close to the vehicle, an electrical fault in a J-box could take out other GSE systems and could explain loss of telemetry and perhaps even cause malfunctions in systems that could lead to an overpressure event...
Question- Is the payload powered up at around the time in the hotfire when this event happened?
The flow with a F9 launch compresses those timelines greatly. What happens if there was an undetected wiring error in those harnesses? In my view this opens up a bunch of branches in the fault tree. Aside from providing potential ignition sources close to the vehicle, an electrical fault in a J-box could take out other GSE systems and could explain loss of telemetry and perhaps even cause malfunctions in systems that could lead to an overpressure event...
I asked a similar question about the customer supplied harness and if that was the case in this test...
Yes, that's what I posted at the time however; Jim stated that it is not where it appears in the Falcon users guide if I understood him correctly. So I left it there...I asked a similar question about the customer supplied harness and if that was the case in this test...
The Catenary Quick Disconnect Jbox on that TE appears to me to be located right at the apparent point of ignition of the flash that initiated the event...
OK, After staying well away form this thread I'll wander in with a question and a bit of discussion.
Question- Is the payload powered up at around the time in the hotfire when this event happened?
Background about the question: One item that is unique for every launch of every rocket is the wire harnesses from S2 or fairing down the pad. They are unique at each launch because the harnesses are destroyed on launch, and because each payload is different from the others.
On other launchers with payloads that I've worked, we check those harnesses out long before day of launch (and in fact do checks of those things way before we ever get to the pad).
The flow with a F9 launch compresses those timelines greatly. What happens if there was an undetected wiring error in those harnesses? In my view this opens up a bunch of branches in the fault tree. Aside from providing potential ignition sources close to the vehicle, an electrical fault in a J-box could take out other GSE systems and could explain loss of telemetry and perhaps even cause malfunctions in systems that could lead to an overpressure event...
No, spacecraft are around 32 voltsMy memory is says different - for some spacecraft. I think we even had to requalify some connectors. I'm referring to large geo comm satellites. I'll check my sources and get back.
What would happen if helium or nitrogen quick connect bursts in S2 quick connect plate?
No, spacecraft are around 32 voltsMy memory is says different - for some spacecraft. I think we even had to requalify some connectors. I'm referring to large geo comm satellites. I'll check my sources and get back.
I'll ask again... How many Amps?At launch? Not that many. You likely only have your vehicle computer, T&C components, and thermal system on. Maybe a GPS receiver as well. Payload, momentum wheels wouldn't be operating.
Thanks, but I'm really looking for the "max current" from to TEL to the LV at any given time in the sequence...I'll ask again... How many Amps?At launch? Not that many. You likely only have your vehicle computer, T&C components, and thermal system on. Maybe a GPS receiver as well. Payload, momentum wheels wouldn't be operating.
No, spacecraft are around 32 voltsMy memory is says different - for some spacecraft. I think we even had to requalify some connectors. I'm referring to large geo comm satellites. I'll check my sources and get back.
I'll ask again... How many Amps?At launch? Not that many. You likely only have your vehicle computer, T&C components, and thermal system on. Maybe a GPS receiver as well. Payload, momentum wheels wouldn't be operating.
Thanks, but I'm really looking for the "max current" from to TEL to the LV at any given time in the sequence...I'll ask again... How many Amps?At launch? Not that many. You likely only have your vehicle computer, T&C components, and thermal system on. Maybe a GPS receiver as well. Payload, momentum wheels wouldn't be operating.
One last thought on the rocket swaying or vibrating theory. The more I think about it, the less I like this idea anyway. But with that being said the logic used here to shoot it down was that accelerometers would have seen it, and SpaceX would have said so. And that rockets flex, and are designed to do so, etc. Yes, clearly. So the sway/vibration was seen, SpaceX though it was within tolerance (maybe on the high side, maybe not) so it doesn't raise any flags. But what if their tolerances were dead wrong. Or what if tolerances stacked up in such a way between the TEL and Rocket, or something that was supposed to move or vice versa unexpectedly failed, such that "normal/acceptable" movements now became an issue?
It would be visible in pad videos. Did you see the onboard camera view of the rocket flexing? The flex was on the order of feet and not inches and the vehicle skin crinkled and uncrinkled.
Ever heard of the term rate gyro package on launch vehicles? Not those in the main guidance system but a package installed on the side of the booster (can't be interior because the location is usually on a prop tank). What this package does is measure the attitude and rates of the vehicle at that location which the guidance system compares with its gyros at its location. They are different because the vehicle flexes from wind and thrust vehicle control. The guidance system uses this information to adjust the control gains, so that it doesn't chase its tail all over the sky.
Yes, this is exactly my point. SpaceX knows exactly how/where/when/how much the rocket moved. Everything is within those tolerances. What if their tolerances are wrong?
Upon your edit:
Wouldn't these same sensors (along with the He pressure gauges) also pick up a failure in the He system. That triangulation is how they got their failure mode past time. What failure would not have been picked up by these sensors and cameras?
I'll ask again... How many Amps?At launch? Not that many. You likely only have your vehicle computer, T&C components, and thermal system on. Maybe a GPS receiver as well. Payload, momentum wheels wouldn't be operating.
Keep in mind that while the TEL is horizontal, transporting rocket and payload from HIF to pad, the entire weight is on the pads, including dynamic loads from any subtle imperfections in the roadway. The force those pads exert on the rocket structure during transport would dwarf anything that could be developed by vortex shedding or run-away harmonics. IMHO, neither the TEL nor it's pads should be candidates for damaging the structure, especially to the point of rupturing the skin.
No, spacecraft are around 32 voltsMy memory is says different - for some spacecraft. I think we even had to requalify some connectors. I'm referring to large geo comm satellites. I'll check my sources and get back.
It is a standard for all spacecraft
Now that's interesting. The trajectory of one of the debris passes right through the object containing the delta pixel identified on my previous post.
Thanks, wish we had similar info for Falcon...No, spacecraft are around 32 voltsMy memory is says different - for some spacecraft. I think we even had to requalify some connectors. I'm referring to large geo comm satellites. I'll check my sources and get back.
It is a standard for all spacecraft
Proton User Guide says GSE to spacecraft wiring limited to 100 V.
Sea Launch User Guide says customer limited to 150V and 58 Amps until launch.
Delta !V User Guide says 11A and 126 VDC max.
I think our case was similar. High voltage capability was added sometime after our program started. Test equipment had to be upgraded to test the cables.
Keep in mind that while the TEL is horizontal, transporting rocket and payload from HIF to pad, the entire weight is on the pads, including dynamic loads from any subtle imperfections in the roadway. The force those pads exert on the rocket structure during transport would dwarf anything that could be developed by vortex shedding or run-away harmonics. IMHO, neither the TEL nor it's pads should be candidates for damaging the structure, especially to the point of rupturing the skin.
I think there is some sort of support strap that carries the weight of the rocket when it is horizontal. You can see it in some of the photos
A nice photo of the SpaceX strongback on Kwajalein in 2006 shows the base of the Falcon 1's strongback and the plumbing leading up from it. (http://www.delong.com/WebPhotos/Kwajalein-2006-11/large-47.html)There are three thick pipes, one especially well thermally insulated (so it's probably for LOX). There are also 3 comparatively thin metal tubes paralleling the main pipes. Electrical conduits? Hydraulic lines?Another picture shows the three thinner lines are carrying gaseous nitrogen (http://www.delong.com/WebPhotos/Kwajalein-2006-11/large-53.html). They may be similar to the 6 unidentified lines (https://forum.nasaspaceflight.com/index.php?topic=30981.msg1584378#msg1584378) on the SLC-40 strongback.
I started off in the wild & wacky thread, but I actually think my idea may not belong there after all (presumptuous, perhaps)
My scenario, with apologies if it has already been debunked:
RP-1 tank is full, but still at ambient pressure with relief vent open (assumes existence of said vent valve -- there must be one to safe the stage after payload separation.)
During LOX filling, a little bit of LOX somehow leaks into the RP-1 tank (assumes unknown manufacturing defect-- a bad weld, thermal shock, who knows)
Leaking LOX is warmed by RP-1, boils and vaporizes (even after freezing RP-1 locally into blobs of wax) and starts to vigorously agitate contents of RP-1 tank. Surface of RP-1 inside the tank is roiled by GOX bubbles, creating small droplets of RP-1 aerosol (much like air bubbles in a Jacuzzi will create tiny suspended water droplets) in an enriched oxygen atmosphere, filling the ullage space. None of this is visible in external camera imagery or in telemetry, since the RP-1 tank remains vented at ambient pressure during second stage tanking operations. All temperatures and pressures are green, and any accelerometers register the normal signature of tanking. Since GOX is being generated in the RP-1 tank, the RP-1 aerosol mixture is chased out of the RP-1 tank through the relief vent(s), at a height roughly coincident with the top of the RP-1 tank, and wafts outside the vehicle. Eventually, the plume finds an ignition source in the nearby TEL systems and detonates.
This does not involve any vapors. It does not involve strange sources of fuels-- the obvious fuel is RP-1. It does not involve cyrogenic effects related to cooled LOX. It would not show up in telemetry until the explosion. It is set off outside the vehicle. It would plausibly occur only during LOX tanking.
Any fatal flaws here? In the other thread it was claimed the RP-1 tank wouldn't be vented to ambient air...
So, for flex induced by vortex shedding from the fairing to be a significant issue, here are some of the pre-conditions:
1. The payload and fairing are attached.
2. The wind speed is 9.8m/s.
3. The grabber is closed.
4. The fuel load is such that the natural frequency matches the shedding forces.
5. The position of the grabbers matches the node of the mode shape.
6. The cradle (and hence the lower pad) is fixed in position by the grabber and the pin joint on the strongback, which is vastly stiffer and stronger than the rocket.
That's a long (and therefore unlikely) set of preconditions! Further, if the rocket is *designed to flex* (as Jim has stated), the result is still: nothing. A bit of a sway, observable on telemetry.
So, for the fairing, shedding leads to forces oscillating at 0.177 and 0.354 Hz.By your own math, it would take *at least* three seconds to reach maximum deflection. That's order of magnitudes slower than the event is seen to develop, and would be incredibly obvious from the accelerometer data on the stage.
[...]
If all of the conditions were met, the onset of a significant flex could be quite sudden, and may not register on accelerometers as anything other than a step function at the same time as the start of the fast fire.
I started off in the wild & wacky thread, but I actually think my idea may not belong there after all (presumptuous, perhaps)
My scenario, with apologies if it has already been debunked:
RP-1 tank is full, but still at ambient pressure with relief vent open (assumes existence of said vent valve -- there must be one to safe the stage after payload separation.)
During LOX filling, a little bit of LOX somehow leaks into the RP-1 tank (assumes unknown manufacturing defect-- a bad weld, thermal shock, who knows)
Leaking LOX is warmed by RP-1, boils and vaporizes (even after freezing RP-1 locally into blobs of wax) and starts to vigorously agitate contents of RP-1 tank. Surface of RP-1 inside the tank is roiled by GOX bubbles, creating small droplets of RP-1 aerosol (much like air bubbles in a Jacuzzi will create tiny suspended water droplets) in an enriched oxygen atmosphere, filling the ullage space. None of this is visible in external camera imagery or in telemetry, since the RP-1 tank remains vented at ambient pressure during second stage tanking operations. All temperatures and pressures are green, and any accelerometers register the normal signature of tanking. Since GOX is being generated in the RP-1 tank, the RP-1 aerosol mixture is chased out of the RP-1 tank through the relief vent(s), at a height roughly coincident with the top of the RP-1 tank, and wafts outside the vehicle. Eventually, the plume finds an ignition source in the nearby TEL systems and detonates.
This does not involve any vapors. It does not involve strange sources of fuels-- the obvious fuel is RP-1. It does not involve cyrogenic effects related to cooled LOX. It would not show up in telemetry until the explosion. It is set off outside the vehicle. It would plausibly occur only during LOX tanking.
Any fatal flaws here? In the other thread it was claimed the RP-1 tank wouldn't be vented to ambient air...
I like it as well. At least it fits all information we have so far and does not require much magic. However, the stage was tested at McGregor. If there was a leak from the LOX to the fuel tank, shouldnt that have made a big-bada-boom at the test already?
why SpaceX silent?
I started off in the wild & wacky thread, but I actually think my idea may not belong there after all (presumptuous, perhaps)This assumes that the RP1 tank is at ambient pressure and has an open relief valve. That seems very unlikely to me.
My scenario, with apologies if it has already been debunked:
RP-1 tank is full, but still at ambient pressure with relief vent open (assumes existence of said vent valve -- there must be one to safe the stage after payload separation.)
During LOX filling, a little bit of LOX somehow leaks into the RP-1 tank (assumes unknown manufacturing defect-- a bad weld, thermal shock, who knows)
Leaking LOX is warmed by RP-1, boils and vaporizes (even after freezing RP-1 locally into blobs of wax) and starts to vigorously agitate contents of RP-1 tank. Surface of RP-1 inside the tank is roiled by GOX bubbles, creating small droplets of RP-1 aerosol (much like air bubbles in a Jacuzzi will create tiny suspended water droplets) in an enriched oxygen atmosphere, filling the ullage space. None of this is visible in external camera imagery or in telemetry, since the RP-1 tank remains vented at ambient pressure during second stage tanking operations. All temperatures and pressures are green, and any accelerometers register the normal signature of tanking. Since GOX is being generated in the RP-1 tank, the RP-1 aerosol mixture is chased out of the RP-1 tank through the relief vent(s), at a height roughly coincident with the top of the RP-1 tank, and wafts outside the vehicle. Eventually, the plume finds an ignition source in the nearby TEL systems and detonates.
This does not involve any vapors. It does not involve strange sources of fuels-- the obvious fuel is RP-1. It does not involve cyrogenic effects related to cooled LOX. It would not show up in telemetry until the explosion. It is set off outside the vehicle. It would plausibly occur only during LOX tanking.
Any fatal flaws here? In the other thread it was claimed the RP-1 tank wouldn't be vented to ambient air...
1. Can someone tell me what the X on the first image is marking? What is that?
2. And what is that vertical pipe that is in the center of the oval? What is in it?
So, for flex induced by vortex shedding from the fairing to be a significant issue, here are some of the pre-conditions:
1. The payload and fairing are attached.
2. The wind speed is 9.8m/s.
3. The grabber is closed.
4. The fuel load is such that the natural frequency matches the shedding forces.
5. The position of the grabbers matches the node of the mode shape.
6. The cradle (and hence the lower pad) is fixed in position by the grabber and the pin joint on the strongback, which is vastly stiffer and stronger than the rocket.
That's a long (and therefore unlikely) set of preconditions! Further, if the rocket is *designed to flex* (as Jim has stated), the result is still: nothing. A bit of a sway, observable on telemetry.
Yes, it is a long list. My point was that this scenario is not likely to occur with every launch. It may never have occurred. At the absolute most, it has occurred once.
If the rocket sways against a fixed object, the result will not be nothing.So, for the fairing, shedding leads to forces oscillating at 0.177 and 0.354 Hz.By your own math, it would take *at least* three seconds to reach maximum deflection. That's order of magnitudes slower than the event is seen to develop, and would be incredibly obvious from the accelerometer data on the stage.
[...]
If all of the conditions were met, the onset of a significant flex could be quite sudden, and may not register on accelerometers as anything other than a step function at the same time as the start of the fast fire.
Firstly, maximum deflection is reached one quarter of the way through a sinusiod, so certainly less than a second. Secondly, when a vortex is shed in a turbulent stream, the forces generated will not be a smooth sinusiod. They can be extremely abrupt, i.e. a step function.
4. The fuel load is such that the natural frequency matches the shedding forces.
5. The position of the grabbers matches the node of the mode shape.
why SpaceX silent?Welcome to the forum! :) I'm going to venture a guess that they still aren't 100% sure of the cause, so they're not ready to release anything other than they are working on it...
why SpaceX silent?Welcome to the forum! :) I'm going to venture a guess that they still aren't 100% sure of the cause, so they're not ready to release anything other than they are working on it...
The image on the left is the first explosion frame, drawn using the X of light.Another new guy, welcome to the forum! :)
The next explosion frame produced a brighter, and wider X. The image on the right is that second frame, with the lines of the X outlining the wider lines of the X.
It appears the explosion started at the X in the first frame, and them moved upwards along that pipe that I have an oval around.
1. Can someone tell me what the X on the first image is marking? What is that?
2. And what is that vertical pipe that is in the center of the oval? What is in it?
We don't have to come up with a lot of theories about RP1 mixing in the air to explain the fireball. I remember a long time ago where a military jet fighter was demonstrating a roll low over the water at the Toronto Ex. In one frame the tip of the wing hit a wavelet of water. In the next frame the aircraft cartwheeled 270° and in the next frame the whole aircraft was not visible at all due to the large fireball. This plane was travelling at over 400mph so there was no opportunity for gasses to accumulate around the craft.I don't recall that crash Roy, do you remember what year it was? By your description of a cartwheel, if it ripped open a wing tank the rotating fuel would aerosolize and travel via inertia relatively along the aircraft... Do I have what you saw right?
We don't have to come up with a lot of theories about RP1 mixing in the air to explain the fireball. I remember a long time ago where a military jet fighter was demonstrating a roll low over the water at the Toronto Ex. In one frame the tip of the wing hit a wavelet of water. In the next frame the aircraft cartwheeled 270° and in the next frame the whole aircraft was not visible at all due to the large fireball. This plane was travelling at over 400mph so there was no opportunity for gasses to accumulate around the craft.Err - no.
Maybe it did, but didn't ignite, since there was no T/E..I started off in the wild & wacky thread, but I actually think my idea may not belong there after all (presumptuous, perhaps)
My scenario, with apologies if it has already been debunked:
RP-1 tank is full, but still at ambient pressure with relief vent open (assumes existence of said vent valve -- there must be one to safe the stage after payload separation.)
During LOX filling, a little bit of LOX somehow leaks into the RP-1 tank (assumes unknown manufacturing defect-- a bad weld, thermal shock, who knows)
Leaking LOX is warmed by RP-1, boils and vaporizes (even after freezing RP-1 locally into blobs of wax) and starts to vigorously agitate contents of RP-1 tank. Surface of RP-1 inside the tank is roiled by GOX bubbles, creating small droplets of RP-1 aerosol (much like air bubbles in a Jacuzzi will create tiny suspended water droplets) in an enriched oxygen atmosphere, filling the ullage space. None of this is visible in external camera imagery or in telemetry, since the RP-1 tank remains vented at ambient pressure during second stage tanking operations. All temperatures and pressures are green, and any accelerometers register the normal signature of tanking. Since GOX is being generated in the RP-1 tank, the RP-1 aerosol mixture is chased out of the RP-1 tank through the relief vent(s), at a height roughly coincident with the top of the RP-1 tank, and wafts outside the vehicle. Eventually, the plume finds an ignition source in the nearby TEL systems and detonates.
This does not involve any vapors. It does not involve strange sources of fuels-- the obvious fuel is RP-1. It does not involve cyrogenic effects related to cooled LOX. It would not show up in telemetry until the explosion. It is set off outside the vehicle. It would plausibly occur only during LOX tanking.
Any fatal flaws here? In the other thread it was claimed the RP-1 tank wouldn't be vented to ambient air...
I like it as well. At least it fits all information we have so far and does not require much magic. However, the stage was tested at McGregor. If there was a leak from the LOX to the fuel tank, shouldnt that have made a big-bada-boom at the test already?
That may well have been the case, although not obvious as the plane in the second frame having rotated 270° appeared completely intact. Very fuzzy on the year about 1980 give or take several years.We don't have to come up with a lot of theories about RP1 mixing in the air to explain the fireball. I remember a long time ago where a military jet fighter was demonstrating a roll low over the water at the Toronto Ex. In one frame the tip of the wing hit a wavelet of water. In the next frame the aircraft cartwheeled 270° and in the next frame the whole aircraft was not visible at all due to the large fireball. This plane was travelling at over 400mph so there was no opportunity for gasses to accumulate around the craft.I don't recall that crash Roy, do you remember what year it was? By your description of a cartwheel, if it ripped open a wing tank the rotating fuel would aerosolize and travel via inertia relatively along the aircraft... Do I have what you saw right?
Way back about 100 pages or so I presented my theory, but nobody commented on it. Maybe this time I will get some feedback. SpaceX has the unique super-cooled LOX. This means there is little prior experience or documentation. Metal expands or contracts with temperature. The rocket empty may have been slightly hotter than usual in the hot Florida sun, but I don't point this out as most likely cause, just say'n. The LOX tank gets filled chilling the bottom of the tank creating a large temperature difference between it and the top of the RP1 tank just below. Super cooled LOX at -210°C and top of RP1 at least +30°C so a difference of about 240°C. Expansion coefficient of aluminum is 22.2x10^-6 m/°K for a circumference of 3.6m*pi = 11.3m is therefore 60cm by my calculations. I think that will create a huge amount of stress at the LOX/RP1 joint. The bang heard before the explosion could be the tank cracking open. However, this in itself does not explain the fire. Somewhere upthread it is explained that LOX in contact with freshly exposed aluminum will spontaneously ignite. If the crack propagated into the LOX tank and opened up then LOX would escape through the crack and explode.
Way back about 100 pages or so I presented my theory, but nobody commented on it. Maybe this time I will get some feedback. SpaceX has the unique super-cooled LOX. This means there is little prior experience or documentation. Metal expands or contracts with temperature. The rocket empty may have been slightly hotter than usual in the hot Florida sun, but I don't point this out as most likely cause, just say'n. The LOX tank gets filled chilling the bottom of the tank creating a large temperature difference between it and the top of the RP1 tank just below. Super cooled LOX at -210°C and top of RP1 at least +30°C so a difference of about 240°C. Expansion coefficient of aluminum is 22.2x10^-6 m/°K for a circumference of 3.6m*pi = 11.3m is therefore 60cm by my calculations. I think that will create a huge amount of stress at the LOX/RP1 joint. The bang heard before the explosion could be the tank cracking open. However, this in itself does not explain the fire. Somewhere upthread it is explained that LOX in contact with freshly exposed aluminum will spontaneously ignite. If the crack propagated into the LOX tank and opened up then LOX would escape through the crack and explode.
You dropped a decimal place somewhere. 0.000022 [m/m-K] *11.3 [m] * 200 [K] = 0.00498 [m] or about 5 cm.
That's less than 0.5% strain, and commercial Al-Li alloys exhibit a minimum of 12% tensile strain before fracture, at 77 K temps.
Thanks Roy, I had been going to the Ex airshow since the late 60's, good times! I tried to go all three days back then. After the Snowbirds and Nimrod accidents my wife didn't want to go with me anymore. Those were a couple of sad days... :'( The 80's had a few good shows out in Hamilton and London as well! 8)That may well have been the case, although not obvious as the plane in the second frame having rotated 270° appeared completely intact. Very fuzzy on the year about 1980 give or take several years.We don't have to come up with a lot of theories about RP1 mixing in the air to explain the fireball. I remember a long time ago where a military jet fighter was demonstrating a roll low over the water at the Toronto Ex. In one frame the tip of the wing hit a wavelet of water. In the next frame the aircraft cartwheeled 270° and in the next frame the whole aircraft was not visible at all due to the large fireball. This plane was travelling at over 400mph so there was no opportunity for gasses to accumulate around the craft.I don't recall that crash Roy, do you remember what year it was? By your description of a cartwheel, if it ripped open a wing tank the rotating fuel would aerosolize and travel via inertia relatively along the aircraft... Do I have what you saw right?
I like it as well. At least it fits all information we have so far and does not require much magic. However, the stage was tested at McGregor. If there was a leak from the LOX to the fuel tank, shouldnt that have made a big-bada-boom at the test already?Maybe it did, but didn't ignite, since there was no T/E..
Or the leak is new or intermittent...
This assumes that the RP1 tank is at ambient pressure and has an open relief valve. That seems very unlikely to me.
Way back about 100 pages or so I presented my theory, but nobody commented on it. Maybe this time I will get some feedback. SpaceX has the unique super-cooled LOX. This means there is little prior experience or documentation. Metal expands or contracts with temperature. The rocket empty may have been slightly hotter than usual in the hot Florida sun, but I don't point this out as most likely cause, just say'n. The LOX tank gets filled chilling the bottom of the tank creating a large temperature difference between it and the top of the RP1 tank just below. Super cooled LOX at -210°C and top of RP1 at least +30°C so a difference of about 240°C. Expansion coefficient of aluminum is 22.2x10^-6 m/°K for a circumference of 3.6m*pi = 11.3m is therefore 60cm by my calculations. I think that will create a huge amount of stress at the LOX/RP1 joint. The bang heard before the explosion could be the tank cracking open. However, this in itself does not explain the fire. Somewhere upthread it is explained that LOX in contact with freshly exposed aluminum will spontaneously ignite. If the crack propagated into the LOX tank and opened up then LOX would escape through the crack and explode.
You dropped a decimal place somewhere. 0.000022 [m/m-K] *11.3 [m] * 200 [K] = 0.00498 [m] or about 5 cm.
That's less than 0.5% strain, and commercial Al-Li alloys exhibit a minimum of 12% tensile strain before fracture, at 77 K temps.
I thought the RP-1 was also sub-cooled, and loaded before LOX, so the temperature diffference won't be that big either.
Way back about 100 pages or so I presented my theory, but nobody commented on it. Maybe this time I will get some feedback. SpaceX has the unique super-cooled LOX. This means there is little prior experience or documentation. Metal expands or contracts with temperature. The rocket empty may have been slightly hotter than usual in the hot Florida sun, but I don't point this out as most likely cause, just say'n. The LOX tank gets filled chilling the bottom of the tank creating a large temperature difference between it and the top of the RP1 tank just below. Super cooled LOX at -210°C and top of RP1 at least +30°C so a difference of about 240°C. Expansion coefficient of aluminum is 22.2x10^-6 m/°K for a circumference of 3.6m*pi = 11.3m is therefore 60cm by my calculations. I think that will create a huge amount of stress at the LOX/RP1 joint. The bang heard before the explosion could be the tank cracking open. However, this in itself does not explain the fire. Somewhere upthread it is explained that LOX in contact with freshly exposed aluminum will spontaneously ignite. If the crack propagated into the LOX tank and opened up then LOX would escape through the crack and explode.
You dropped a decimal place somewhere. 0.000022 [m/m-K] *11.3 [m] * 200 [K] = 0.00498 [m] or about 5 cm.
That's less than 0.5% strain, and commercial Al-Li alloys exhibit a minimum of 12% tensile strain before fracture, at 77 K temps.
Way back about 100 pages or so I presented my theory, but nobody commented on it. Maybe this time I will get some feedback. SpaceX has the unique super-cooled LOX. This means there is little prior experience or documentation. Metal expands or contracts with temperature. The rocket empty may have been slightly hotter than usual in the hot Florida sun, but I don't point this out as most likely cause, just say'n. The LOX tank gets filled chilling the bottom of the tank creating a large temperature difference between it and the top of the RP1 tank just below. Super cooled LOX at -210°C and top of RP1 at least +30°C so a difference of about 240°C. Expansion coefficient of aluminum is 22.2x10^-6 m/°K for a circumference of 3.6m*pi = 11.3m is therefore 60cm by my calculations. I think that will create a huge amount of stress at the LOX/RP1 joint. The bang heard before the explosion could be the tank cracking open. However, this in itself does not explain the fire. Somewhere upthread it is explained that LOX in contact with freshly exposed aluminum will spontaneously ignite. If the crack propagated into the LOX tank and opened up then LOX would escape through the crack and explode.
You dropped a decimal place somewhere. 0.000022 [m/m-K] *11.3 [m] * 200 [K] = 0.00498 [m] or about 5 cm.
That's less than 0.5% strain, and commercial Al-Li alloys exhibit a minimum of 12% tensile strain before fracture, at 77 K temps.
I thought the RP-1 was also sub-cooled, and loaded before LOX, so the temperature diffference won't be that big either.
Maybe it did, but didn't ignite, since there was no T/E..I started off in the wild & wacky thread, but I actually think my idea may not belong there after all (presumptuous, perhaps)
My scenario, with apologies if it has already been debunked:
RP-1 tank is full, but still at ambient pressure with relief vent open (assumes existence of said vent valve -- there must be one to safe the stage after payload separation.)
During LOX filling, a little bit of LOX somehow leaks into the RP-1 tank (assumes unknown manufacturing defect-- a bad weld, thermal shock, who knows)
Leaking LOX is warmed by RP-1, boils and vaporizes (even after freezing RP-1 locally into blobs of wax) and starts to vigorously agitate contents of RP-1 tank. Surface of RP-1 inside the tank is roiled by GOX bubbles, creating small droplets of RP-1 aerosol (much like air bubbles in a Jacuzzi will create tiny suspended water droplets) in an enriched oxygen atmosphere, filling the ullage space. None of this is visible in external camera imagery or in telemetry, since the RP-1 tank remains vented at ambient pressure during second stage tanking operations. All temperatures and pressures are green, and any accelerometers register the normal signature of tanking. Since GOX is being generated in the RP-1 tank, the RP-1 aerosol mixture is chased out of the RP-1 tank through the relief vent(s), at a height roughly coincident with the top of the RP-1 tank, and wafts outside the vehicle. Eventually, the plume finds an ignition source in the nearby TEL systems and detonates.
This does not involve any vapors. It does not involve strange sources of fuels-- the obvious fuel is RP-1. It does not involve cyrogenic effects related to cooled LOX. It would not show up in telemetry until the explosion. It is set off outside the vehicle. It would plausibly occur only during LOX tanking.
Any fatal flaws here? In the other thread it was claimed the RP-1 tank wouldn't be vented to ambient air...
I like it as well. At least it fits all information we have so far and does not require much magic. However, the stage was tested at McGregor. If there was a leak from the LOX to the fuel tank, shouldnt that have made a big-bada-boom at the test already?
Or the leak is new or intermittent...
Way back about 100 pages or so I presented my theory, but nobody commented on it. Maybe this time I will get some feedback. SpaceX has the unique super-cooled LOX. This means there is little prior experience or documentation. Metal expands or contracts with temperature. The rocket empty may have been slightly hotter than usual in the hot Florida sun, but I don't point this out as most likely cause, just say'n. The LOX tank gets filled chilling the bottom of the tank creating a large temperature difference between it and the top of the RP1 tank just below. Super cooled LOX at -210°C and top of RP1 at least +30°C so a difference of about 240°C. Expansion coefficient of aluminum is 22.2x10^-6 m/°K for a circumference of 3.6m*pi = 11.3m is therefore 60cm by my calculations. I think that will create a huge amount of stress at the LOX/RP1 joint. The bang heard before the explosion could be the tank cracking open. However, this in itself does not explain the fire. Somewhere upthread it is explained that LOX in contact with freshly exposed aluminum will spontaneously ignite. If the crack propagated into the LOX tank and opened up then LOX would escape through the crack and explode.
Way back about 100 pages or so I presented my theory, but nobody commented on it. Maybe this time I will get some feedback. SpaceX has the unique super-cooled LOX. This means there is little prior experience or documentation. Metal expands or contracts with temperature. The rocket empty may have been slightly hotter than usual in the hot Florida sun, but I don't point this out as most likely cause, just say'n. The LOX tank gets filled chilling the bottom of the tank creating a large temperature difference between it and the top of the RP1 tank just below. Super cooled LOX at -210°C and top of RP1 at least +30°C so a difference of about 240°C. Expansion coefficient of aluminum is 22.2x10^-6 m/°K for a circumference of 3.6m*pi = 11.3m is therefore 60cm by my calculations. I think that will create a huge amount of stress at the LOX/RP1 joint. The bang heard before the explosion could be the tank cracking open. However, this in itself does not explain the fire. Somewhere upthread it is explained that LOX in contact with freshly exposed aluminum will spontaneously ignite. If the crack propagated into the LOX tank and opened up then LOX would escape through the crack and explode.
Roy-H...do you think this failure mechanism could originate on electroplated parts, either on the the pad/erector or inside the rocket? Electroplating cycles usually start off by removing all surface oxides, then proceed to deposit the metal. If the electroplated metal fails or cracks, it will expose the oxide free base metal. The electroplated metal will also mismatch CTE's with the base metal, so as these parts undergo temperature cycling, internal stress can rise dramatically, and failure can be catastrophic. I have personally heard nickel plated parts fail when stressed to the point of adhesion failure to the base metal. It can be quite loud. It also can produce a shower of metal flakes. If this type of failure happened around GOX or LOX, it could be quite reactive. When applying this to the pad equipment, I think of hydraulic Pistons & such, when applied to the rocket I have little personal knowledge of material selection. Struts maybe?
As I do not work in the industry, I have no knowledge, but I have not read anything that would make me believe there is any electro-plating done on the tanks. Even if the struts were electro-plated (which I doubt), they would be at uniform temperature and not experience the stress I envisioned.
There is no electroplating. Passivation is what is done, if needed.
Well, I've pretty much beat the USLR video to death at this point.
I could walk into a court room and comfortably declare that in my opinion this video holds no solid evidence of any changes that were a visible precursor to the event.
It's been a fun and educational exercise and required cooperation from several other persons to get to this point.
To me, a summary of the negative results are shown on the video below.
What you are looking at is a video of a moving average of the difference frames, stacked 10 per frame. These are the bottom six difference groups where differences are adjacent frames only. The contrast has been stretched so the differences become visible. If you have the means, further contrast stretching makes some of the clouds more visible. Keep in mind, in the last 10 frames, the stack count is 9, then 8, then 7, so you will perceive brightening, but be careful about drawing conclusions in those last 10 frames. Those frames were independently stacked in groups of 1 or 2 or 3, and those results are essentially the same. The upload to youtube may have added some MPEG artifacts that aren't in the original 16 bit grey scale uncompressed processing.
While there are some interesting and statistically significant changes, none of those changes relate to any actual physical motion of any part of the F9 or TE as seen by the original video. There are areas of clouds that occur to the left of the F9, and some to the right, but these clouds are slow events and from other discussions, appear to be normal clouding events. There are statistical outliers that show in 1 second adjacent stacks, but these are no longer visible when compared to non-adjacent 1 second stacks, i.e. they're noise.
There is one possible exception, but not significantly above the noise levels, i.e. in the 1 SD range. In the last half dozen frames, towards the center of each delta frame there is a diagonal lower left to upper right structure which appears to show a delta in the last few frames, but I wouldn't make a strong case for that. It's possible, but not well supported by the raw data.
If you find this video exciting, I can upload another which uses 50 frame stacks. It will thrill you at an 80% lower level.
Maybe your eyes can see more than mine, but absent another video source, I'm sure you'll all be grateful that I'm done with this approach. I think I'll go to the wild & whacky thread for a while and invent ways to detonate clouds of water vapor.
https://www.youtube.com/watch?v=t4iCR6tbW0Q
Thank you!why SpaceX silent?Welcome to the forum! :) I'm going to venture a guess that they still aren't 100% sure of the cause, so they're not ready to release anything other than they are working on it...
Thank you!why SpaceX silent?Welcome to the forum! :) I'm going to venture a guess that they still aren't 100% sure of the cause, so they're not ready to release anything other than they are working on it...
what some data about 3,000 telemetry channels?
rise in temperature, pressure drop, etc.
Is there any definitive proof that the center of the lens flair is in fact where the LOX fuel line is?
I get the feeling that problem is going to be the use of the densified propellant. It could be that every time the falcon was loaded with the superchilled LOX there was a small chance that there would be an explosion and it was just a matter of time. I little bit of googling shows that a lot of people were concerned with the use of the new denser fuel.
My greatest fear is that the investigation shows that there are unresolvable issues with the densified fuel and spacex is ordered to stop using it. This would create all kinds of issues even assuming no changes need to be made to the rocket.
Many rockets including Antares use subcooled fuel without issue. SpaceX was pushing it further, but it isn't complete uncharted territory.
The LOX fuel line is NOT at the center of the explosion. It goes in at the bottom of the stage through the interstage. The explosion was very near the center of the stage.
In answer to a PM about the "possible" change that doesn't meet my definition of statistically significant. I've circled it in the cropped image below.
In answer to a PM about the "possible" change that doesn't meet my definition of statistically significant. I've circled it in the cropped image below.
Aren't those spots the exact centers of two of the initial diffraction flares?
In answer to a PM about the "possible" change that doesn't meet my definition of statistically significant. I've circled it in the cropped image below.
Aren't those spots the exact centers of two of the initial diffraction flares?
With all due respect, as I've posted twice previously, the "diffraction flares" are internal lens barrel reflections. They point to the center of the putative "X" if and only if the lens and the light source are at the center of the field of view and all of the internals of the lens are symmetric, which is unlikely if this is a zoom lens.
Since the brightest illumination is offset from the center of the field of view, the "diffraction flares" are pointing to a location different from the brightest point. How much offset requires knowing the lens, having the lens, testing the lens, and calculating the "flare" deviation as the source drifts from the center of the field of view.
If the the "flare" analysis points to the area identified, then I assure you, the brightest point is not there. It's probably someplace to the right, but without knowing or testing the lens, all I can be sure of is the flare "X" probably doesn't point to the brightest spot, which is most likely to the right of the "X", but could be left depending on the element count in the lens, and where the reflections occur in the lens barrel.
In answer to a PM about the "possible" change that doesn't meet my definition of statistically significant. I've circled it in the cropped image below.
Aren't those spots the exact centers of two of the initial diffraction flares?
With all due respect, as I've posted twice previously, the "diffraction flares" are internal lens barrel reflections. They point to the center of the putative "X" if and only if the lens and the light source are at the center of the field of view and all of the internals of the lens are symmetric, which is unlikely if this is a zoom lens.
Since the brightest illumination is offset from the center of the field of view, the "diffraction flares" are pointing to a location different from the brightest point. How much offset requires knowing the lens, having the lens, testing the lens, and calculating the "flare" deviation as the source drifts from the center of the field of view.
If the the "flare" analysis points to the area identified, then I assure you, the brightest point is not there. It's probably someplace to the right, but without knowing or testing the lens, all I can be sure of is the flare "X" probably doesn't point to the brightest spot, which is most likely to the right of the "X", but could be left depending on the element count in the lens, and where the reflections occur in the lens barrel.
Apologies. I'm not very good at recalling everything that's happened or all of the well made points in this thread. :-[
In answer to a PM about the "possible" change that doesn't meet my definition of statistically significant. I've circled it in the cropped image below.
Aren't those spots the exact centers of two of the initial diffraction flares?
With all due respect, as I've posted twice previously, the "diffraction flares" are internal lens barrel reflections. They point to the center of the putative "X" if and only if the lens and the light source are at the center of the field of view and all of the internals of the lens are symmetric, which is unlikely if this is a zoom lens.
Since the brightest illumination is offset from the center of the field of view, the "diffraction flares" are pointing to a location different from the brightest point. How much offset requires knowing the lens, having the lens, testing the lens, and calculating the "flare" deviation as the source drifts from the center of the field of view.
If the the "flare" analysis points to the area identified, then I assure you, the brightest point is not there. It's probably someplace to the right, but without knowing or testing the lens, all I can be sure of is the flare "X" probably doesn't point to the brightest spot, which is most likely to the right of the "X", but could be left depending on the element count in the lens, and where the reflections occur in the lens barrel.
Oh, please tell us :)QuoteThank you!
what some data about 3,000 telemetry channels?
rise in temperature, pressure drop, etc.
I don't need telemetry to tell you that both have happened :)
.In answer to a PM about the "possible" change that doesn't meet my definition of statistically significant. I've circled it in the cropped image below.
Aren't those spots the exact centers of two of the initial diffraction flares?
With all due respect, as I've posted twice previously, the "diffraction flares" are internal lens barrel reflections. They point to the center of the putative "X" if and only if the lens and the light source are at the center of the field of view and all of the internals of the lens are symmetric, which is unlikely if this is a zoom lens.
Since the brightest illumination is offset from the center of the field of view, the "diffraction flares" are pointing to a location different from the brightest point. How much offset requires knowing the lens, having the lens, testing the lens, and calculating the "flare" deviation as the source drifts from the center of the field of view.
If the the "flare" analysis points to the area identified, then I assure you, the brightest point is not there. It's probably someplace to the right, but without knowing or testing the lens, all I can be sure of is the flare "X" probably doesn't point to the brightest spot, which is most likely to the right of the "X", but could be left depending on the element count in the lens, and where the reflections occur in the lens barrel.
Here is a starry photo made through a _refractor_ telescope (Skywatcher Esprit-100). As you see, there _are_ diffraction spikes, and they _are_ centered on each star.
Diffraction spikes are caused by the spider suspending the secondary mirror in a telescope.
Symmetrical pairs of spikes indicate the spider is a symmetrical four-vane assembly.
Well, there was a rise in temperature and there was a loss of pressure.Oh, please tell us :)QuoteThank you!
what some data about 3,000 telemetry channels?
rise in temperature, pressure drop, etc.
I don't need telemetry to tell you that both have happened :)
Here is a starry photo made through a _refractor_ telescope (Skywatcher Esprit-100). As you see, there _are_ diffraction spikes, and they _are_ centered on each star.Probably from the non-circularly-symmetric iris in the camera. The telescope is mostly likely circularly symmetric and cannot form spikes.
This is why I think they need some non-lens non-image based IR based sensing across the pad and erector. One good way is with the STTR I suggested they look at.Diffraction spikes are caused by the spider suspending the secondary mirror in a telescope.
Symmetrical pairs of spikes indicate the spider is a symmetrical four-vane assembly.
Guys/Gals go have your debate. This video's X doesn't point to the "brightest spot" which is probably a diffuse "brightest spot". Show me the math that converges the X to a single point. There is math for that.
I'll watch your debate and intervene if someone goes totally whacko.
Meanwhile I'm posting on the whacko thread.
Diffraction spikes are caused by the spider suspending the secondary mirror in a telescope.
Symmetrical pairs of spikes indicate the spider is a symmetrical four-vane assembly.
Diffraction spikes are caused by the spider suspending the secondary mirror in a telescope.
Symmetrical pairs of spikes indicate the spider is a symmetrical four-vane assembly.
In this particular case, it's a refractor scope, not a reflector.
This is why I think they need some non-lens non-image based IR based sensing across the pad and erector. One good way is with the STTR I suggested they look at.
Gee Doug, it only took 74 pages for you to agree... ;D
http://forum.nasaspaceflight.com/index.php?topic=30981.1380
Not me... It was the FSW at the Common Bulkhead or the mount not the COPV itself... I'm still a "Weldologist"... ;DGee Doug, it only took 74 pages for you to agree... ;D
http://forum.nasaspaceflight.com/index.php?topic=30981.1380
Yeah, well, you were still flogging the COPVs at that point, as well. I was trying to come up with a more likely single-point failure that arose out of a single root cause, rather than adding two or more main failure modes together... ;)
Suppose one small section of the weld attaching the common bulkhead to the inner tank walls was weak or faulty. This assumption posits that SpaceX does not inspect every single weld on every single vehicle.
I would like to posit that SpaceX inspects every single weld on every single vehicle, and/or that no welds were weak or faulty.
The weld failure exposed a fresh-cut aluminum-lithium edge, which is reactive in LOX, and the shock wave generated by the weld failure provided all the remaining energy needed to start the metal on fire, right along the weld line connecting the common bulkhead to the tank skin.
They thoroughly inspect every FSW join in-situ on the welding machine, using various ultrasonic systems that have been developed specifically for FSW. They've been doing so since they started, back on the Falcon 1's. By now are arguably one of the most experienced companies in the world with such techniques.
The weld failure exposed a fresh-cut aluminum-lithium edge, which is reactive in LOX, and the shock wave generated by the weld failure provided all the remaining energy needed to start the metal on fire, right along the weld line connecting the common bulkhead to the tank skin.
The initial flash expressed the fast fire of the tank skin, fed by the LOX behind it. As regular air crept in and LOX immersion was replaced by air and combustion gasses, the rate of combustion of the tank skin slowed, and the fire receded, accounting for the very bright initial flash and its subsequent dimming.
A point of trivia for the welding calibration and inspection and in support of it being done frome day one is that the standard procedure for doing the spot welds on the Atlas (this is the Atlas al la 1956 incarnation) that prior to usage of the spot welder two stainless steel test coupons one for each sheet associated with its specific source role id oriented in the exact way that the welding is to be done are welded together and then this coupon goes off to the lab to be x-rayed and then sliced through the weld to inspect the metal microscopically for proper welding. So I doubt that SpaceX is less diligent than what was done for ICBMs mass produced in the 100+ quantities over just a few years prior to the 1960s.
I would like to posit that SpaceX inspects every single weld on every single vehicle, and/or that no welds were weak or faulty.
Same words apply to every launch vehicle since day one.
Somewhere upthread it is explained that LOX in contact with freshly exposed aluminum will spontaneously ignite. If the crack propagated into the LOX tank and opened up then LOX would escape through the crack and explode.
Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #3055 on: 09/18/2016 12:00 AM »
LikeQuote
Quote from: glennfish on 09/17/2016 10:27 PM
Quote from: RotoSequence on 09/17/2016 10:12 PM
Quote from: glennfish on 09/17/2016 09:27 PM
In answer to a PM about the "possible" change that doesn't meet my definition of statistically significant. I've circled it in the cropped image below.
Aren't those spots the exact centers of two of the initial diffraction flares?
With all due respect, as I've posted twice previously, the "diffraction flares" are internal lens barrel reflections. They point to the center of the putative "X" if and only if the lens and the light source are at the center of the field of view and all of the internals of the lens are symmetric, which is unlikely if this is a zoom lens.
Since the brightest illumination is offset from the center of the field of view, the "diffraction flares" are pointing to a location different from the brightest point. How much offset requires knowing the lens, having the lens, testing the lens, and calculating the "flare" deviation as the source drifts from the center of the field of view.
If the the "flare" analysis points to the area identified, then I assure you, the brightest point is not there. It's probably someplace to the right, but without knowing or testing the lens, all I can be sure of is the flare "X" probably doesn't point to the brightest spot, which is most likely to the right of the "X", but could be left depending on the element count in the lens, and where the reflections occur in the lens barrel.
Here is a starry photo made through a _refractor_ telescope (Skywatcher Esprit-100). As you see, there _are_ diffraction spikes, and they _are_ centered on each star.
Diffraction spikes are caused by the spider suspending the secondary mirror in a telescope.
Symmetrical pairs of spikes indicate the spider is a symmetrical four-vane assembly.
Guys/Gals go have your debate. This video's X doesn't point to the "brightest spot" which is probably a diffuse "brightest spot". Show me the math that converges the X to a single point. There is math for that.
Additionally, on frame 2, notice how that bulge, on the center, right edge of the fireball, is ejected out further than the rest of the fireball.The video recording only represents 16.7ms samples of what actually happened, so the apparent center of the explosion may well not be the actual starting/ignition point of the explosion, just the center of the bulk of the fuel for the initial FAE.
Its height is very close to the center of the X's. Remember the X on explosion frame one (EF1) is slightly lower than the X on EF2, as is this bulge.
This may represent ejection from the presumed point of the EF1 explosion, the X in frame one, that is at the right edge of the F9, and slightly lower than the X in this frame.
And no debris is present, also supporting that the explosion was at the exterior surface of the rocket, at the point of the X on EF1.
I personally think the 75-77K oxygen frost buildup on the exterior is a more likely cause.
And no debris is present, also supporting that the explosion was at the exterior surface of the rocket, at the point of the X on EF1.Good point.
[...]
The point spread function is the light pattern you get on the sensor from a single point of incoming light, like a star. Any image you get will be the point spread function convolved with the incoming pattern of light.
[...]
So here's the kicker: the aperture spikes are generally circularly symmetrical. That means the center of those X's are indeed the brightest spots in the image. For off-center bright spots in a wide angle lens, there can be some distortion, but we don't have those effects here.
. . . . and see if *y'all* think . . . .
Re: SpaceX Falcon 9 - AMOS-6 - (Pad Failure) - DISCUSSION THREAD
« Reply #3082 on: Today at 10:03 AM »
The video recording only represents 16.7ms samples of what actually happened, so the apparent center of the explosion may well not be the actual starting/ignition point of the explosion, just the center of the bulk of the fuel for the initial FAE.
just the center of the bulk of the fuel for the initial FAE.
There's only a limited number of possible energy source combinations for the "fire" in the fireball:
Diffraction spikes are caused by the spider suspending the secondary mirror in a telescope.
Symmetrical pairs of spikes indicate the spider is a symmetrical four-vane assembly.
Guys/Gals go have your debate. This video's X doesn't point to the "brightest spot" which is probably a diffuse "brightest spot". Show me the math that converges the X to a single point. There is math for that.
I'll watch your debate and intervene if someone goes totally whacko.
Meanwhile I'm posting on the whacko thread.
The weld failure exposed a fresh-cut aluminum-lithium edge, which is reactive in LOX, and the shock wave generated by the weld failure provided all the remaining energy needed to start the metal on fire, right along the weld line connecting the common bulkhead to the tank skin.
I really hate to disagree with a fellow Minnesotan, but I must.
First, I looked through a number of NASA technical reports on the flammability of various AL-LI alloys. The results basically concluded that they were very expensive but had about 10 X lower flammability ratings than pure aluminum. The testing was in LOX environments and specific tests to determine how to burn the metal in LOX. AL-LI was rated as better than stainless steel and considered an ideal tank material, albeit not recommended for turbo pumps and other environments where friction could raise the temperature to the melting point, which was the flash point.
Granted that a weld failure could generate the 1kC plus temperature required for AL-LI alloy burn initiation, the burn rates were extremely slow, measured in fractions of feet per second. While disconcerting and fatal for the studied mission configurations, they were well below the 1k fps conflagration indicated in the video.
Finally, to purport that the energy dump of the fracture was sufficient to be the initiator detonation, that's cool, but you have to have a structural failure consistent with a 16 ms event. My best guess says that event required the equivalent to 50 to 100 pounds of TNT. At 4 megajouls per kg, were talking about a minimum of 88 megajoules of energy release from a crack.
All this has to happen in 16 milliseconds.
I really have a hard time swallowing that, even after a Jucy Lucy at Matts and 2 pints of Coors.
I can't offer a better theory, but this one to me, fails the sniff test.
Going for the 3rd pint now.
. . . . and see if *y'all* think . . . .
Sorry Doug, it's just hard to take seriously a Minnesotean who writes Southern. I'm pretty sure everyone here knows the correct way to say that in 'Sotean is " . . . and see if yousguys think . . . . ".
Diffraction spikes are caused by the spider suspending the secondary mirror in a telescope.
Symmetrical pairs of spikes indicate the spider is a symmetrical four-vane assembly.
Guys/Gals go have your debate. This video's X doesn't point to the "brightest spot" which is probably a diffuse "brightest spot". Show me the math that converges the X to a single point. There is math for that.
I'll watch your debate and intervene if someone goes totally whacko.
Meanwhile I'm posting on the whacko thread.
Optics is my profession.
The diffraction spike should cross at the point of maximum brightness.
They are not reflections from the lens barrel. (Those would be "ghosts" and look different.)
The two spikes indicate to linear "obstructions", either spiders or aperture blades in front of or within the "lens", or even photographing through a window screen.
The existence of "spiders" is not common for lenses, but they could have used a telescope with spiders. We could ask.
What software did Mason use in his "Detailed Analysis ... " video?
It's interesting because he syncs up the audio with the video and points out that there is a pop and what definitely sounds like a metal screech/groan 5 seconds before the explosion.
Diffraction spikes are caused by the spider suspending the secondary mirror in a telescope.
Symmetrical pairs of spikes indicate the spider is a symmetrical four-vane assembly.
Guys/Gals go have your debate. This video's X doesn't point to the "brightest spot" which is probably a diffuse "brightest spot". Show me the math that converges the X to a single point. There is math for that.
I'll watch your debate and intervene if someone goes totally whacko.
Meanwhile I'm posting on the whacko thread.
Optics is my profession.
The diffraction spike should cross at the point of maximum brightness.
They are not reflections from the lens barrel. (Those would be "ghosts" and look different.)
The two spikes indicate to linear "obstructions", either spiders or aperture blades in front of or within the "lens", or even photographing through a window screen.
The existence of "spiders" is not common for lenses, but they could have used a telescope with spiders. We could ask.
Comga, I am not an optical engineer (but I could ask one tomorrow, I am on a astronomy workshop and have access to about 5 or so). Could the diffraction cross come from something like a lens hood?
https://en.wikipedia.org/wiki/File:Five_lens_hoods.JPG
A ghost would actually pretty helpful because it would likely not be overexposed. Unfortunately, US Launch Report seems to have used good gear ;)
While some of the commentary on this thread has been covered in this video, it hasn't been put together in such a comprehensive way to my knowledge.
It's interesting because he syncs up the audio with the video and points out that there is a pop and what definitely sounds like a metal screech/groan 5 seconds before the explosion. he then postulates (similar to jim's best guess at least as I understand) that it's most likely an he COPV breaking through the barrier between two tanks in s2. he also briefly empathizes w/difficulty noticed by many here re:extracting info from frames preceding the deflagration.
Detailed analysis of Spacex Rocket Explosion (https://www.youtube.com/watch?v=EhdQPaABFK0)
(via: peter de selding https://twitter.com/pbdes)
can anyone explain the line or tongue of flame extending down the S1 in the Frame1 image[first frame to show explosion]. it can't be RP1 and cant be just a reflection of GOX vapor.
Additionally, on frame 2, notice how that bulge, on the center, right edge of the fireball, is ejected out further than the rest of the fireball.
Its height is very close to the center of the X's. Remember the X on explosion frame one (EF1) is slightly lower than the X on EF2, as is this bulge.
This may represent ejection from the presumed point of the EF1 explosion, the X in frame one, that is at the right edge of the F9, and slightly lower than the X in this frame.
And no debris is present, also supporting that the explosion was at the exterior surface of the rocket, at the point of the X on EF1.
Way back about 100 pages or so I presented my theory, but nobody commented on it. Maybe this time I will get some feedback. SpaceX has the unique super-cooled LOX. This means there is little prior experience or documentation. Metal expands or contracts with temperature. The rocket empty may have been slightly hotter than usual in the hot Florida sun, but I don't point this out as most likely cause, just say'n. The LOX tank gets filled chilling the bottom of the tank creating a large temperature difference between it and the top of the RP1 tank just below. Super cooled LOX at -210°C and top of RP1 at least +30°C so a difference of about 240°C. Expansion coefficient of aluminum is 22.2x10^-6 m/°K for a circumference of 3.6m*pi = 11.3m is therefore 60cm by my calculations. I think that will create a huge amount of stress at the LOX/RP1 joint. The bang heard before the explosion could be the tank cracking open. However, this in itself does not explain the fire. Somewhere upthread it is explained that LOX in contact with freshly exposed aluminum will spontaneously ignite. If the crack propagated into the LOX tank and opened up then LOX would escape through the crack and explode.
You dropped a decimal place somewhere. 0.000022 [m/m-K] *11.3 [m] * 200 [K] = 0.00498 [m] or about 5 cm.
That's less than 0.5% strain, and commercial Al-Li alloys exhibit a minimum of 12% tensile strain before fracture, at 77 K temps.
I thought the RP-1 was also sub-cooled, and loaded before LOX, so the temperature diffference won't be that big either.
I believe the RP1 tank is not filled to the top, so the top of the tank could be considerably warmer than the liquid portion below. However this is a moot point as explained by envy881.
just the center of the bulk of the fuel for the initial FAE.
what FAE?
Here's spacejulien's s-curve.
...
The left image shows the temperature profile, the right image shows the deformation (times 20). Ideally this would have been all one image but I just banged it out and this was easier. You have to kind of eyeball the vertical shrinkage between the two. The cut lines show the levels to which I filled the tanks with LOX (top) and kerosene (bottom). Note that the kerosene is in contact with the bottom of the intertank bulkhead.
I didn't put any stringers in, they would greatly increase the strains and add local strain concentrations. I don't know what the stringer design is, and the guys designing this thing are using the same analysis I am, so they'll have optimized that issue already.
Some things that I didn't expect:- The S curve happens below the spot on the tank where the S curve is, in the equithermal part of the tank wall.
- The bottom of the kerosene tank gets pushed up by the strains on the tank above it.
- When LOX and kerosene touch opposite sides of a thin plate of AlLi, LOX wins, utterly. The kerosene might actually freeze solid, but if it doesn't the convection coefficient of liquid kerosene getting a bit more dense from cooling is nothing like the convection coefficient of LOX boiling on contact. The metal wall is driven under the LOX boiling temperature, at which point the LOX switches to all-liquid convection.
Does anyone know if the kerosene actually does contact the bottom of the LOX dome, and if so, do they have some insulation on it to prevent the kerosene from forming wax on the bottom of that dome? It seems like you could easily grow several cm of wax, which would be heavy and unusable as fuel.
Another thing I learned is that the stringer design is going to be complicated by the thermal loads of reentry, when the level of the LOX and kerosene is changing and a significant amount of heat comes in the side.
can anyone explain the line or tongue of flame extending down the S1 in the Frame1 image[first frame to show explosion]. it can't be RP1 and cant be just a reflection of GOX vapor.Why do you think it can't be just a reflection? For me it actually does, because this 'tongue' is visible in many frames of the explosion and its brightness follows the brightness of the actual *kaboom* up at S2 level. It also does not develop or consumes GOX.
Previous discussion this thread with someone who was looking at the separate RGB channels. It's most visible in the blue.So you mean it's GOX reflection?
It's very consistent with a water vapor cloud absorption spectrum between the fireball and the camera.
just the center of the bulk of the fuel for the initial FAE.
what FAE?
I see a fireball. We know that needs fuel and air. (You can argue that technically it was not an explosion but that is semantics at this point).
So if this is not a FAE what would you call it?
You can argue that it was not the 'initial event' but I don't see how you can argue against a FAE
I'm also a bit shocked to see that the rings are in four sections held together by bolted bridge plates.
I'd also be curious if there is any iron in that hardware, as I've heard iron and LOX are bad together.
just the center of the bulk of the fuel for the initial FAE.
what FAE?
I see a fireball. We know that needs fuel and air. (You can argue that technically it was not an explosion but that is semantics at this point).
So if this is not a FAE what would you call it?
You can argue that it was not the 'initial event' but I don't see how you can argue against a FAE
In the previous explosion, after launch... that spot where the explosion appears to start, is that at the same place, the common bulkhead, that this explosion appears to start?no
Stringers should be only in first stage RP-1 tank: likely no stringers in LOX tank nor in second stage.
Speaking of second stage common bulkhead, would an explosion occur if the lox and fuel were to mix following its failure?
Stringers should be only in first stage RP-1 tank: likely no stringers in LOX tank nor in second stage.
Where you take this information from. Maybe there are less stringers there, but for tank integrity, they are incredibly good. You forget that even the second stage has to be able to carry ~11 metric tons under 30G acceleration. That's difficult to do with bare 4,5mm LiAl skin. Don't you find?
Stringers should be only in first stage RP-1 tank: likely no stringers in LOX tank nor in second stage.
Where you take this information from. Maybe there are less stringers there, but for tank integrity, they are incredibly good. You forget that even the second stage has to be able to carry ~11 metric tons under 30G acceleration.
can anyone explain the line or tongue of flame extending down the S1 in the Frame1 image[first frame to show explosion]. it can't be RP1 and cant be just a reflection of GOX vapor.
Previous discussion this thread with someone who was looking at the separate RGB channels. It's most visible in the blue. It's very consistent with a water vapor cloud absorption spectrum between the fireball and the camera.
Stringers should be only in first stage RP-1 tank: likely no stringers in LOX tank nor in second stage.
Where you take this information from. Maybe there are less stringers there, but for tank integrity, they are incredibly good. You forget that even the second stage has to be able to carry ~11 metric tons under 30G acceleration. That's difficult to do with bare 4,5mm LiAl skin. Don't you find?
Stringers should be only in first stage RP-1 tank: likely no stringers in LOX tank nor in second stage.
Where you take this information from. Maybe there are less stringers there, but for tank integrity, they are incredibly good. You forget that even the second stage has to be able to carry ~11 metric tons under 30G acceleration.
THIRTY G acceleration?
Don't you mean something more like three?
Max thrust of Mvac of 210,000 pounds, and a 24,000 pound payload would be about 8.75 TWR. But that is ignoring the mass of the 2nd stage (let's go with near-empty mass just before shutdown). Also, the Mvac can throttle down to about 39%. So include 2nd stage mass (near-empty), and 39% throttle-down and it would be right around 3 G's.
can anyone explain the line or tongue of flame extending down the S1 in the Frame1 image[first frame to show explosion]. it can't be RP1 and cant be just a reflection of GOX vapor.
Previous discussion this thread with someone who was looking at the separate RGB channels. It's most visible in the blue. It's very consistent with a water vapor cloud absorption spectrum between the fireball and the camera.
The "tongue of flame" or "water vapor cloud" can't be off at some distance between the fireball and the camera, because the lower portion of the tail is behind a vertical bar of the TEL, so it's right next to the rocket.
What might be even more enlightening, not only about this observation but compared to everything that has been observed so far, is that the curve is most visible in the blue channel, and what's blue besides reflections of the sky is the blue of a flame, indicating the hottest and most oxygen rich portion, hotter than white.
Full disclosure I'm going to try the power of suggestion here. First, you might want to light a candle and remind yourself how rarely you pay attention to any part of the flame other than the white tip, that a closer look reveals a hint of blue at the base, and above the blue is a translucent grayish core that remains inside the white of the flame.
Next, you might want to view the "1/250x Speed" slow motion video on You Tube, and freeze it at the 34 second mark. If you have a Roku or Google Chromecast and can watch it on a large screen TV, even better.
https://www.youtube.com/watch?v=HXqG-R8O39g
You might see the same features I'm seeing if you view the full anomaly as a flame of a candle, all the way down to the middle of the diagonal brace of the TEL, which extends to the left at the lower half of the 1st stage. There would be the blue and hottest part, and the origin or closer to it, not at the attention grabbing fireball. What also can be considered are the blue flames given by Bunsen burners, gas range tops, and propane torches, all fed by gases much further below.
What might be even more enlightening, not only about this observation but compared to everything that has been observed so far, is that the curve is most visible in the blue channel, and what's blue besides reflections of the sky is the blue of a flame, indicating the hottest and most oxygen rich portion, hotter than white.
Full disclosure I'm going to try the power of suggestion here. First, you might want to light a candle and remind yourself how rarely you pay attention to any part of the flame other than the white tip, that a closer look reveals a hint of blue at the base, and above the blue is a translucent grayish core that remains inside the white of the flame.
You might see the same features I'm seeing if you view the full anomaly as a flame of a candle, all the way down to the middle of the diagonal brace of the TEL, which extends to the left at the lower half of the 1st stage. There would be the blue and hottest part, and the origin or closer to it, not at the attention grabbing fireball. What also can be considered are the blue flames given by Bunsen burners, gas range tops, and propane torches, all fed by gases much further below.
I totally missed something in your comment.
In the BLUE channel, the cloud is darker, not brighter. That means, less blue is coming through, not more. In the red and green channels, it's mostly bright, a tad less in the green, and not at all in the red.
There is structure visible in the blue channel, wipe out on the red, and barely something maybe there in the green.
Essentially, it's brightest in the red channel, slightly less bright in the green, and clearly not as bright in the blue.
I totally missed something in your comment.
In the BLUE channel, the cloud is darker, not brighter. That means, less blue is coming through, not more. In the red and green channels, it's mostly bright, a tad less in the green, and not at all in the red.
There is structure visible in the blue channel, wipe out on the red, and barely something maybe there in the green.
Essentially, it's brightest in the red channel, slightly less bright in the green, and clearly not as bright in the blue.
Ok, thanks for clarifying that part, but I'm still inclined to look further down since a specific cause has not been found further up.
A large apartment complex fire I worked back in my Red Cross days had an extremely odd cause that I recalled in association with my analysis here. A resident had backed into his parking space, and when he started up his car again, heat and sparks from his exhaust ignited the parched grass in front of his building. The flame that resulted traveled across 20-30 feet of lawn and did considerable damage to his building and others next to it.
It isn't obvious right away, but the entire length of the left side of the rocket is lit up almost as instantaneously as above.
1. Why would the shorter kerosene tanks have stringers but the longer LOX tanks have none?
2. And why would the first stage kerosene tank have stringers when the shorter second stage LOX tank has none?
3. Is it that the rocket is moved with the kerosene tanks unpressurized and the LOX tanks pressurized?
4. Because that skin is fabricated in barrels, it would be just too easy to make each barrel section a different thickness. Because the stresses seen at each section are different, the weight savings available are significant.
1. Why would the shorter kerosene tanks have stringers but the longer LOX tanks have none?
2. And why would the first stage kerosene tank have stringers when the shorter second stage LOX tank has none?
3. Is it that the rocket is moved with the kerosene tanks unpressurized and the LOX tanks pressurized?
4. Because that skin is fabricated in barrels, it would be just too easy to make each barrel section a different thickness. Because the stresses seen at each section are different, the weight savings available are significant.
1. They both do
2. they both do.
3 Neither, they are pressurized for flight.
4. No.
a. The weight saving would be minimal
b. The costs would increase
c. also welding two different thicknesses would cause issues.
What might be even more enlightening, not only about this observation but compared to everything that has been observed so far, is that the curve is most visible in the blue channel, and what's blue besides reflections of the sky is the blue of a flame, indicating the hottest and most oxygen rich portion, hotter than white.
Full disclosure I'm going to try the power of suggestion here. First, you might want to light a candle and remind yourself how rarely you pay attention to any part of the flame other than the white tip, that a closer look reveals a hint of blue at the base, and above the blue is a translucent grayish core that remains inside the white of the flame.
You might see the same features I'm seeing if you view the full anomaly as a flame of a candle, all the way down to the middle of the diagonal brace of the TEL, which extends to the left at the lower half of the 1st stage. There would be the blue and hottest part, and the origin or closer to it, not at the attention grabbing fireball. What also can be considered are the blue flames given by Bunsen burners, gas range tops, and propane torches, all fed by gases much further below.
I totally missed something in your comment.
In the BLUE channel, the cloud is darker, not brighter. That means, less blue is coming through, not more. In the red and green channels, it's mostly bright, a tad less in the green, and not at all in the red.
There is structure visible in the blue channel, wipe out on the red, and barely something maybe there in the green.
Essentially, it's brightest in the red channel, slightly less bright in the green, and clearly not as bright in the blue.
I'd be wary about comparing colour channel brightnesses. It depends on the sensitivity of the sensor to those colours which is determined by the colour mask, assuming it's a bayer sensor. Without knowing that (and it might be possible to find it out if we know the make and model of camera ), making judgements might be foolish. It also depends on the processing when converting from bayer to RGB, probably via YUV on the way.
Fodder for "cracks in LOX tank" theories. During STS-133 (https://en.wikipedia.org/wiki/STS-133) fueling, the shuttle's external LOX tank had multiple significant cracks caused by the thermal stress of LOX loading. The stresses were known and well modeled, but the failure was actually in imperfect heat treating of a batch of internal Al/Li stringers, (http://www.cbsnews.com/network/news/space/home/spacenews/files/ad71f2f20c5a6a6998966aac915dab86-140.html) reducing their strength far below design and expectation.
That tank loading failure had a simulaneous minor but beyond-flight-limit gaseous H2 leak due to a poorly fitting umbilical connector. The 20,000 ppm leak was detected by GSE sensors.
The post-mission final report from NASA. (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120014466.pdf)
My take on all this is that the LOX tank might have ruptured into the RP-1 tank. It would almost certainly form an explosive cloud and an ignition source could be there, too. What I don't really understand is how all of this can happen so quickly, within a single frame of video. (It could have happened a little earlier, just not evident on the video, but wouldn't the telemetry then tell the story?)
SpaceX is saying that they expect only a 3 month delay. If there was a problem with the rocket, especially a tank failure, the delay would be longer than 3 months. I would think 9 to 18 months. To me, a 3 month delay tells me they believe it was an external explosion but they don't have definitive evidence or root cause yet.My take on all this is that the LOX tank might have ruptured into the RP-1 tank. It would almost certainly form an explosive cloud and an ignition source could be there, too. What I don't really understand is how all of this can happen so quickly, within a single frame of video. (It could have happened a little earlier, just not evident on the video, but wouldn't the telemetry then tell the story?)
I think you may have answered your own question. If the common bulkhead ruptured internally, the combustion event started inside the stage and didn't become visible until the tank wall(s) burst. In that scenario, you'd expect a very sudden appearance of a large fireball. One moment it's not there, next moment it is. Compare to a video of a hydrogen balloon being exploded.
Telemetry may already have told that story; you seem to be assuming it hasn't. The question is, if that was in fact the story, what was the root cause. They may know it was an internal failure from telemetry but not yet be able to pinpoint a root cause.
SpaceX is saying that they expect only a 3 month delay. If there was a problem with the rocket, especially a tank failure, the delay would be longer than 3 months. I would think 9 to 18 months. To me, a 3 month delay tells me they believe it was an external explosion but they don't have definitive evidence or root cause yet.My take on all this is that the LOX tank might have ruptured into the RP-1 tank. It would almost certainly form an explosive cloud and an ignition source could be there, too. What I don't really understand is how all of this can happen so quickly, within a single frame of video. (It could have happened a little earlier, just not evident on the video, but wouldn't the telemetry then tell the story?)
I think you may have answered your own question. If the common bulkhead ruptured internally, the combustion event started inside the stage and didn't become visible until the tank wall(s) burst. In that scenario, you'd expect a very sudden appearance of a large fireball. One moment it's not there, next moment it is. Compare to a video of a hydrogen balloon being exploded.
Telemetry may already have told that story; you seem to be assuming it hasn't. The question is, if that was in fact the story, what was the root cause. They may know it was an internal failure from telemetry but not yet be able to pinpoint a root cause.
Was that SpaceX, NASA or 3rd party source?SpaceX is saying that they expect only a 3 month delay. If there was a problem with the rocket, especially a tank failure, the delay would be longer than 3 months. I would think 9 to 18 months. To me, a 3 month delay tells me they believe it was an external explosion but they don't have definitive evidence or root cause yet.My take on all this is that the LOX tank might have ruptured into the RP-1 tank. It would almost certainly form an explosive cloud and an ignition source could be there, too. What I don't really understand is how all of this can happen so quickly, within a single frame of video. (It could have happened a little earlier, just not evident on the video, but wouldn't the telemetry then tell the story?)
I think you may have answered your own question. If the common bulkhead ruptured internally, the combustion event started inside the stage and didn't become visible until the tank wall(s) burst. In that scenario, you'd expect a very sudden appearance of a large fireball. One moment it's not there, next moment it is. Compare to a video of a hydrogen balloon being exploded.
Telemetry may already have told that story; you seem to be assuming it hasn't. The question is, if that was in fact the story, what was the root cause. They may know it was an internal failure from telemetry but not yet be able to pinpoint a root cause.
Ms. Shotwell's statement was only a best-case scenario. I have heard from more than one source that RTF will not be this year.
Why would the shorter kerosene tanks have stringers but the longer LOX tanks have none?Because the RP-1 tank (when horizontal and unpressurized) takes the greatest part of the load of octaweb and engines.
And why would the first stage kerosene tank have stringers when the shorter second stage LOX tank has none?Because it is shorter and carries no loads during handling and transport .
Is it that the rocket is moved with the kerosene tanks unpressurized and the LOX tanks pressurized?Both pressurized for flight, unpressurized for handling and likely partially pressurized for road transport.
Or is it that the LOX tanks, due to the larger pressure changes they see, can't use stringers, and so use thicker skin sections? I have also read the 4.5 mm thick spec for the Falcon's skins, and I don't believe it. Because that skin is fabricated in barrels, it would be just too easy to make each barrel section a different thickness. Because the stresses seen at each section are different, the weight savings available are significant.See Jim and dorkmo. FSW has to be carefully adjusted for thickness variations
The stringers in that tank from 2006 appear to be continuous, rather than divided into sections as in the pictures I posted. I wonder what they are using now?Stringers are friction stir welded during preparation of barrels.
This is very true. I remember back in 2003 when the Columbia accident investigation was still very much underway that NASA initially projected a RTF time frame of October of the same year. So SpaceX isn't alone in setting "too-optimistic" RTF time frames.SpaceX is saying that they expect only a 3 month delay. If there was a problem with the rocket, especially a tank failure, the delay would be longer than 3 months. I would think 9 to 18 months. To me, a 3 month delay tells me they believe it was an external explosion but they don't have definitive evidence or root cause yet.My take on all this is that the LOX tank might have ruptured into the RP-1 tank. It would almost certainly form an explosive cloud and an ignition source could be there, too. What I don't really understand is how all of this can happen so quickly, within a single frame of video. (It could have happened a little earlier, just not evident on the video, but wouldn't the telemetry then tell the story?)
I think you may have answered your own question. If the common bulkhead ruptured internally, the combustion event started inside the stage and didn't become visible until the tank wall(s) burst. In that scenario, you'd expect a very sudden appearance of a large fireball. One moment it's not there, next moment it is. Compare to a video of a hydrogen balloon being exploded.
Telemetry may already have told that story; you seem to be assuming it hasn't. The question is, if that was in fact the story, what was the root cause. They may know it was an internal failure from telemetry but not yet be able to pinpoint a root cause.
Ms. Shotwell's statement was only a best-case scenario. I have heard from more than one source that RTF will not be this year.
My take on all this is that the LOX tank might have ruptured into the RP-1 tank. It would almost certainly form an explosive cloud and an ignition source could be there, too. What I don't really understand is how all of this can happen so quickly, within a single frame of video. (It could have happened a little earlier, just not evident on the video, but wouldn't the telemetry then tell the story?)
I think you may have answered your own question. If the common bulkhead ruptured internally, the combustion event started inside the stage and didn't become visible until the tank wall(s) burst. In that scenario, you'd expect a very sudden appearance of a large fireball. One moment it's not there, next moment it is. Compare to a video of a hydrogen balloon being exploded.
Telemetry may already have told that story; you seem to be assuming it hasn't. The question is, if that was in fact the story, what was the root cause. They may know it was an internal failure from telemetry but not yet be able to pinpoint a root cause.
...Shotwell was very clear that they still did not know the root cause and that November was best case. Secondary sources were less clear and then people started drawing conclusions from what a November RTF "implied." It implies that people should really find the primary source of any quote. :)This is very true. I remember back in 2003 when the Columbia accident investigation was still very much underway that NASA initially projected a RTF time frame of October of the same year. So SpaceX isn't alone in setting "too-optimistic" RTF time frames.SpaceX is saying that they expect only a 3 month delay. If there was a problem with the rocket, especially a tank failure, the delay would be longer than 3 months. I would think 9 to 18 months. To me, a 3 month delay tells me they believe it was an external explosion but they don't have definitive evidence or root cause yet.Ms. Shotwell's statement was only a best-case scenario. I have heard from more than one source that RTF will not be this year.
SpaceNews quotes her as saying “We’re anticipating getting back to flight, being down for about three months, so getting back to flight November, the November timeframe,”. Anticipate can be defined as "To see as a probable occurrence; expect". Seems rather definitive to me....Shotwell was very clear that they still did not know the root cause and that November was best case. Secondary sources were less clear and then people started drawing conclusions from what a November RTF "implied." It implies that people should really find the primary source of any quote. :)This is very true. I remember back in 2003 when the Columbia accident investigation was still very much underway that NASA initially projected a RTF time frame of October of the same year. So SpaceX isn't alone in setting "too-optimistic" RTF time frames.SpaceX is saying that they expect only a 3 month delay. If there was a problem with the rocket, especially a tank failure, the delay would be longer than 3 months. I would think 9 to 18 months. To me, a 3 month delay tells me they believe it was an external explosion but they don't have definitive evidence or root cause yet.Ms. Shotwell's statement was only a best-case scenario. I have heard from more than one source that RTF will not be this year.
[Photo of Elon standing inside LOX tank]
[Photo of Elon standing inside LOX tank]
What are all of those projections into the LOX tank in your picture? Too many to be sensors, and we're told there are no stringers so they can't be stringer mount points. Not big enough to be anti-swirl vanes. Too regular to be ad-hoc mount points for COPVs/etc. I'm out of ideas!
Are those the copv struts we can see in the distance?
Are all these mount points welded? It looks like it. I can't see a bolt head.
[Photo of Elon standing inside LOX tank]
What are all of those projections into the LOX tank in your picture? Too many to be sensors, and we're told there are no stringers so they can't be stringer mount points. Not big enough to be anti-swirl vanes. Too regular to be ad-hoc mount points for COPVs/etc. I'm out of ideas!
Who said no stringers?
Monocoque (/ˈmɒnəˌkɒk, -ˌkoʊk/), also structural skin, is a structural system where loads are supported through an object's external skin, similar to an egg shell. The word monocoque is a French term for "single shell" or (of boats) "single hull".[1] A true monocoque carries both tensile and compressive forces within the skin and can be recognised by the absence of a load carrying internal frame.
Are those the copv struts we can see in the distance?Those look like the COPV mount points and the FSW common bulkhead that I have been mentioning in the thread. The interface on the common bulkhead looks like a FSW lap joint that can pass a NDE and can still experience a failure in the paper I cited...
Are all these mount points welded? It looks like it. I can't see a bolt head.
Are those the copv struts we can see in the distance?
Are all these mount points welded? It looks like it. I can't see a bolt head.
Any new whispers from inside the investigation?It's not yet Friday ;)
That's for public companies that have stock prices to protect.Any new whispers from inside the investigation?It's not yet Friday ;)
*based on always releasing bad news on a Friday, and good news on a Monday
Any new whispers from inside the investigation?It's not yet Friday ;)
*based on always releasing bad news on a Friday, and good news on a Monday
Any new whispers from inside the investigation?It's not yet Friday ;)
*based on always releasing bad news on a Friday, and good news on a Monday
After CRS-7, Musk announced a root cause roughly three weeks later, on Monday, July 20.
Based on that precedent, I was guessing that they'd announce a failure cause either today (three weeks after the failure), or this coming Monday (in keeping with their "announce bad news on Monday" precedent), or in a brief statement at IAC.
Still working on the Falcon fireball investigation. Turning out to be the most difficult and complex failure we have ever had in 14 years.
Sorry to belabor the point, SpaceNews is a secondary source. If you follow anything closely enough you will discover that people are misquoted/partially quoted all the time. I'm not implying ill intent, it's just another example of the the telephone game (https://en.wikipedia.org/wiki/Chinese_whispers)....SpaceNews quotes her as saying “We’re anticipating getting back to flight, being down for about three months, so getting back to flight November, the November timeframe,”. Anticipate can be defined as "To see as a probable occurrence; expect". Seems rather definitive to me.
Shotwell was very clear that they still did not know the root cause and that November was best case. Secondary sources were less clear and then people started drawing conclusions from what a November RTF "implied." It implies that people should really find the primary source of any quote. :)
Peter B. de Selding
@pbdes
SpaceX President Shotwell: We anticipate return to flight in November, meaning down for three months. Next flight from CCAFS, then to VAFB.
Peter B. de Selding
@pbdes
SpaceX's Shotwell: Nov return to flight is our best hope. We still haven't isolated the cause or whether its origin was rocket or ground.
I wonder if it could be useful to setup a new second-stage-only on a temporary lower structure, in a safe place in case of a successful recreated explosion, with a rebuilt lower supply tower and try to replicate the situation, testing the possible root causes they can test, or simply looking at dozens others fill and empty sequences of LOX in the second stage. The second stage would be equipped with more sensors, and so the exterior.
They don't need to light the engines, so McGregor is not needed nor it has to be at risk.
If at a loss, after weeks of testing all day long and analyzing data, they could try to damage on purpose some structures and see if this actually lend to a potentially explosive situation.
I mean, initial conditions of the accident are not all replicable and known, but if nothing else, testing many times trying to fail again can help to understand by experiment.
They have the money and workforce to do this in parallel to what they are already doing.
They have to be sure to find a reasonable root cause, and be quick to exit this impasse.
It's like folks aren't listening.Imagined the thread broadcast as audio...
It's like folks aren't listening.Imagined the thread broadcast as audio...
Rich idea, had to share.
Sorry.
Too many variables. Too much a shot in the dark. Too hard to convince of a causal chain of events.
I wonder if it could be useful to setup a new second-stage-only on a temporary lower structure, in a safe place in case of a successful recreated explosion, with a rebuilt lower supply tower and try to replicate the situation, testing the possible root causes they can test, or simply looking at dozens others fill and empty sequences of LOX in the second stage. The second stage would be equipped with more sensors, and so the exterior.
They don't need to light the engines, so McGregor is not needed nor it has to be at risk.
If at a loss, after weeks of testing all day long and analyzing data, they could try to damage on purpose some structures and see if this actually lend to a potentially explosive situation.
I mean, initial conditions of the accident are not all replicable and known, but if nothing else, testing many times trying to fail again can help to understand by experiment.
They have the money and workforce to do this in parallel to what they are already doing.
They have to be sure to find a reasonable root cause, and be quick to exit this impasse.
If you look at it another way, they've been doing this since their first F9 launch: they set up the rocket, fill and empty it, test fire it, and then just for good measure, put a payload on it and send it to orbit. Since this last one failed, they can use the data recovered to figure out why the previous ones didn't blow up.
in other words, it could take a long time for a test article to explode like this. or it may never explode like this. or it may explode in a completely different way. if your car breaks down, you don't drive around another car until it also breaks down and then assume that the first car also had the exact same problem. Even if they both have a flat tire, one could be manufacturing defects and the other could be a puncture. The extra data is only going to get in the way.
The primary things to investigate are assuming O2 was readily present (and the initial explosion was outside the vehicle), how did the fuel become present and what ignighted it. Those 2 things could be tested without a rocket or only part of the rocket such as the interface panel.If you look at it another way, they've been doing this since their first F9 launch: they set up the rocket, fill and empty it, test fire it, and then just for good measure, put a payload on it and send it to orbit. Since this last one failed, they can use the data recovered to figure out why the previous ones didn't blow up.
in other words, it could take a long time for a test article to explode like this. or it may never explode like this. or it may explode in a completely different way. if your car breaks down, you don't drive around another car until it also breaks down and then assume that the first car also had the exact same problem. Even if they both have a flat tire, one could be manufacturing defects and the other could be a puncture. The extra data is only going to get in the way.
I disagree. Falcon 9 FT is a different rocket from previous versions, expecially concerning the fuel loading phase and temperature, so not so much useful previous data. We now know something went wrong. Was it LOX and contamination? Test. Was it LOX and exposed Al ? Test. Was there a mixture of RP1 and LOX, a COPV, oxygen ice forming? Test what-if scenarios, measure and gain data, try to fail and see how big and different it happens. Then reconsider everything. There are many use cases and combination of adverse factors ? Sure, but if by the data you have you cannot understand what went wrong, you need more data. And it's better to get data by tests than by another burst up payload.
Too much and unplanned data is spam, but modeling and simulation cannot be the only tools you have. And even a month earlier in finding a root cause is worth the effort, even more if SpaceX ends into no clear answer.
As for McGregor, I don't know if there are redundant test stands for second stages, I just meant one thing is to have a test stand you hope and plan to not damage, another thing is to have a test stand you are happy to destroy, perhaps more than one time :-)
I know we generally are not supposed to talk about what is on /r/SpaceX here but they have a thread about COPV harmonics being the root cause. That would be a bad thing, I think.
How much performance/density would they lose if they moved the COPV tanks outside of the tank?
Those tiny lead weights around the rim of your wheels? Those are there to provide a counteracting mass to damp out resonance in your spinning wheels.
While watching the USSpace video for the umpteenth time, and looking for something completely different, found something compelling to me.Note that the video is edited, with a cut at :50 s (22 s before the explosion), so we have no way of knowing the timeline before that...
Watch the video from the :40s mark to the event and note the strong venting from LOX vent, starting about :48s mark. The vent stream looks to strongly vent towards the TEL until the event. Re-watching the video looking at this, it seems to me it leads to the event.
Then looking the the countdown timeline:
T-10:00 LOX venting for fast fill.
Best I can tell from reading this entire thread is that the event occurred around the T-8:00 mark.
Since there is only appx. 22s of this stronger venting until the event, could this venting indicate an experiment by SpaceX in 'accelerated fast fill'.
[...]
Those tiny lead weights around the rim of your wheels? Those are there to provide a counteracting mass to damp out resonance in your spinning wheels.
Interesting- I had always presumed that it was much simpler than that, to put the CG of the wheel in the middle.
I know we generally are not supposed to talk about what is on /r/SpaceX here but they have a thread about COPV harmonics being the root cause. That would be a bad thing, I think.
How much performance/density would they lose if they moved the COPV tanks outside of the tank?
IF that is indeed the case, harmonics per se isn't the problem - resonance is. And resonant frequency is easy to change in a system. Those tiny lead weights around the rim of your wheels? Those are there to provide a counteracting mass to damp out resonance in your spinning wheels. So, IF the problem is a harmonic resonance in the COPV tanks (e.eg., vibrations set up in response to rapidly loading propellants, THEN the solution is equally-simple. Add a tiny bit of mass, or simply change the physical arrangement of whatever part was oscillating, to damp the vibration and prevent the resonance.