From the update on the SpaceX site:
"We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success. Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success."
Someone remind me which mission Flight 13 is with?
From the update on the SpaceX site:
"We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success. Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success."
We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success. Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success.
The real story here is flights 14 & 15 on LAND!! That's before the end of this year.
From the update on the SpaceX site:
"We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success. Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success."
The real story here is flights 14 & 15 on LAND!! That's before the end of this year.
Does this mean they have gotten precise in hitting a designated landing location?
I wonder if F9R-Dev 2 is going to be needed if they keep collecting data with these flights?
'with no required refurbishment' - this is a big deal. Until this launch SpaceX has been saying that they didn't know how much refurbishment was required.
How about an old oil platform. They are perfectly stable.
From: SPACEX SOFT LANDS FALCON 9 ROCKET FIRST STAGE (http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falcon-9-rocket-first-stage)From the update on the SpaceX site:
"We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success. Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success."
The real story here is flights 14 & 15 on LAND!! That's before the end of this year.
Does this mean they have gotten precise in hitting a designated landing location?
I wonder if F9R-Dev 2 is going to be needed if they keep collecting data with these flights?
At this point, we are highly confident of being able to land successfully on a floating launch pad or back at the launch site and refly the rocket with no required refurbishment. However, our next couple launches are for very high velocity geostationary satellite missions, which don’t allow enough residual propellant for landing. In the longer term, missions like that will fly on Falcon Heavy, but until then Falcon 9 will need to fly in expendable mode.Given the wording, they may target a platform at see first, before attempting to land on land. Either way, this is way sooner than I expected!
We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success. Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success.
My guess is that they are extrapolating from F9R and the telemetry they received from the stage.'with no required refurbishment' - this is a big deal. Until this launch SpaceX has been saying that they didn't know how much refurbishment was required.
I'm not sure what they meant there, but it seems like something they wouldn't be able to state accurately UNTIL they could inspect a star returned to land. (End of this year(?), if flight 14 will land)
The outlier reason might be IF they were able to recover a significant amount of vital hardware. Have we heard if anything was recovered?
From the update on the SpaceX site:
"We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success. Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success."
The real story here is flights 14 & 15 on LAND!! That's before the end of this year.
Does this mean they have gotten precise in hitting a designated landing location?
I wonder if F9R-Dev 2 is going to be needed if they keep collecting data with these flights?
The real question is, is this news about potentially attempting solid-surface landings part of the post Chris had to hide all those months ago?Yeah, wonder what happened with that! Been meaning to ask... Chris?
Or possibly some sort of barge. :o
Checked the recommended helipad sizes (https://new.rotor.com/portals/1/publication/Heliports_25_Most_Asked_Questions.pdf)
65 square feet to 100 square feet - small indeed.
The landing burn almost looked like it was sputtering. Why would it look like that?My guess is that it's just the turbo pump's flame being blown back by the descent.
Actually, according to the linked report, 65 foot square to 100 foot square, i.e. a 65 ft by 65 ft to 100 ft by 100 ft foot area. 65 square feet would be 8ft x 8ft, which would fit only model helicopters :).
For the solid surface, I vote iceberg.
How much of a trip will it be seeing 3 cores land within seconds of each other!!
Striking that they talk about landing on a floating launch pad.
And if they give the next water landing a low probability of success, does that mean they are planning to trim some margins and see if they get away with it?
One implication of the news that they only plan one more ocean 'landing' before trying to land on land, is that the next ocean landing attempt (flight #13 - presumably next CRS mission) will have to demonstrate a pinpoint landing. So presumably that will be the first flight with the grid fins installed.
A pending patent doesn't have any legal force, it simply puts others on notice that a patent has been applied for. It may be accepted or rejected.
A pending patent doesn't have any legal force, it simply puts others on notice that a patent has been applied for. It may be accepted or rejected.
This isn't my area of expertise but I believe that a patent can be accepted by the patent offfice but still not be valid in court.
If they now have pinpoint accuracy, I wonder if we could maybe see quadcopter footage of a landing in the future.
A pending patent doesn't have any legal force, it simply puts others on notice that a patent has been applied for. It may be accepted or rejected.
This isn't my area of expertise but I believe that a patent can be accepted by the patent offfice but still not be valid in court.
If they now have pinpoint accuracy, I wonder if we could maybe see quadcopter footage of a landing in the future.
What makes you think that they have achieved pinpoint accuracy? Isn't that what the grid fins are about?
If they now have pinpoint accuracy, I wonder if we could maybe see quadcopter footage of a landing in the future.Give a man an inch ... :P
If they now have pinpoint accuracy, I wonder if we could maybe see quadcopter footage of a landing in the future.
What makes you think that they have achieved pinpoint accuracy? Isn't that what the grid fins are about?
What makes you think I said they had?
We keep talking about platforms but, what about a deserted island perhaps. Anything out in the Atlantic and within the flight profile that would meet the criteria? Another wild idea. Could you land it on the deck of an aircraft carrier? Yeah, I know the risks but planes have crashed on decks before.
If they now have pinpoint accuracy, I wonder if we could maybe see quadcopter footage of a landing in the future.
What makes you think that they have achieved pinpoint accuracy? Isn't that what the grid fins are about?
If they now have pinpoint accuracy, I wonder if we could maybe see quadcopter footage of a landing in the future.
What makes you think that they have achieved pinpoint accuracy? Isn't that what the grid fins are about?
Exactly - if they had, I would assume that we would see landing footage from a boat position very close to the intended spot. (and there certainly might be such footage, not yet released)
...And that assumes that it will be a floating platform to begin with, which is questionable. (Yes, they have raised it as a possibility, but they want to do a land landing)
...And that assumes that it will be a floating platform to begin with, which is questionable. (Yes, they have raised it as a possibility, but they want to do a land landing)
SpaceX might be trying to kill two birds with one stone. It is still not clear if the core of the FH can make it back to the KSC landing pad. The core of the FH might need a floating landing pad at all times. So might as well test the floating landing pad with a F9 flight.
Incidentally, here is the Blue Origin patent with the sea going platform:
http://www.google.com/patents/US8678321
Launching Falcon 9 Heavy from the planned Texas facility: would the core have velocity/range to make it to Florida or any Gulf Coast location? I assume not all launch trajectories are going to be straight east?
I'd wondered about the flyback portion--it consumes significant propellant and a floating platform should be robust enough to suffer a bad landing without much damage.
Now all we need to do is crowd-source a deconvolution of the icing effects on the lens. No sweat, right? ::)That would be interesting.
Launching Falcon 9 Heavy from the planned Texas facility: would the core have velocity/range to make it to Florida or any Gulf Coast location? I assume not all launch trajectories are going to be straight east?
I'd wondered about the flyback portion--it consumes significant propellant and a floating platform should be robust enough to suffer a bad landing without much damage.
If FH flies with cross-feed, it could reach Florida. But remember that they can also choose to launch FH without cross-feed. In that case it would fly like the Delta IV-Heavy, where the core throttles down after liftoff. The DH core could in that case make it back to the launch site.
I guess it all depends on how heavy the DH payload will be.
The remaining questions are whether a landed stage can be easily secured and economically returned. A RTLS does eliminate the time and trouble of a remote recovery.It may be that even when RTLS is the preferred option, an alternative landing site may be ready if something makes the launch site unusable - though the weather at the launch site shouldn't change much in 10 minutes.
I find it absolutely hilarious that the recovered video that we fixed was in some ways better than this one!
So who wants to guess what "solid surface" means?
Concrete floats, right?Concrete ships do
The remaining questions are whether a landed stage can be easily secured and economically returned. A RTLS does eliminate the time and trouble of a remote recovery.It may be that even when RTLS is the preferred option, an alternative landing site may be ready if something makes the launch site unusable - though the weather at the launch site shouldn't change much in 10 minutes.
If they land down range then it's not just the return, they also have to handle the weather at that location, so they'd need to either abort a launch if there was bad weather at the down range landing site, or launch without recovery, or have 3 or 4 options so they can pick the one with good weather. Right?
Incidentally, here is the Blue Origin patent with the sea going platform:
http://www.google.com/patents/US8678321
Granted March 25, 2014!
That's news.
Now all we need to do is crowd-source a deconvolution of the icing effects on the lens. No sweat, right? ::)That would be interesting.
With a reasonably consistent alteration of the picture made by that ice, I wonder whether something 'simple' like using the first image from "the landing burn begins" to create a filter to apply to the rest would work. Of course you'd need to have a clean photo or some basic template of what it should have looked like without the ice.... not so easy.
In any case videographer or fx work rather than fixing the technical underpinnings as in the last video.
Lens iced over for the most part:
http://youtu.be/CQnR5fhCXkQ
Cool. Hopefully they'll be able to address that on the next attempt to prefent it getting iced over. Be great to have a full clean video of it. Be cool if they can get a video boat out in the area too to get a nice surface video.
Going forward, we are taking steps to minimize the build up of ice and spots on the camera housing in order to gather improved video on future launches.
From the update on the SpaceX site:
"We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success. Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success."
The real story here is flights 14 & 15 on LAND!! That's before the end of this year.
Does this mean they have gotten precise in hitting a designated landing location?
I wonder if F9R-Dev 2 is going to be needed if they keep collecting data with these flights?
From the same update...
At this point, we are highly confident of being able to land successfully on a floating launch pad or back at the launch site and refly the rocket with no required refurbishment
Or possibly some sort of barge. :o
There is the possibility that flight 14 will be to a floating "launch" pad and then flight 15 will touchdown on land. With respect to CRS-4 having a low probability of success, is it possible that it could be a repeat of Cassiope, where the rocket spins out of control due to lack of legs?
Bonus: Here is the article saved for posterity: https://web.archive.org/web/20140722210143/http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falcon-9-rocket-first-stage (https://web.archive.org/web/20140722210143/http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falcon-9-rocket-first-stage)
Probably the best system would be what is used for on board racing cameras. A clear film is stored on rollers and passed in front of the lens carrying all the offending gunk with it. SpaceX could probably buy the system(s) off the shelf.Lens iced over for the most part:
http://youtu.be/CQnR5fhCXkQ
Cool. Hopefully they'll be able to address that on the next attempt to prefent it getting iced over. Be great to have a full clean video of it. Be cool if they can get a video boat out in the area too to get a nice surface video.
Could be both a barge and a carrier. Where's the Ranger now days?Alas, The Ranger is no more!
The Aircraft Carrier might not be far off.
(http://www.recyclingtoday.com/FileUploads/image/NavySaratoga.jpg)
USS Saratoga sold for scrap to Esco Marine in Brownsville Texas.
Link
http://www.recyclingtoday.com/navy-esco-marine-scraps-carrier.aspx (http://www.recyclingtoday.com/navy-esco-marine-scraps-carrier.aspx)
Looking at the video, I was surprised at how late the landing legs deployed. Kind of thought those would have been used to slow spin but they deployed very late. Looks like those thrusters were able to null everything out. As far as the irregular flames, not so sure but wonder if there is some thruster firing there too.
Incidentally, here is the Blue Origin patent with the sea going platform:
http://www.google.com/patents/US8678321
I'm curious, is this the camera smashing through the inter-stage? ???
I don't really know what this could be other than that.
edit; then to than. :)
From the update on the SpaceX site:
"We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success. Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success."
I'm curious, is this the camera smashing through the inter-stage? ???
I don't really know what this could be other than that.
edit; then to than. :)
The video doesn't seem to show any data link drop outs, or any bit flips, or even any visible macroblocks! Is it possible that this was extracted from on-board storage?
A few notes:You noticed that too!
...
3. The rocket plumes are oddly patterned in this video, with a series of parallel "interference patterns", no doubt due to the arrangement of the three firing engines.
...
Concrete floats, right?Concrete ships do
One implication of the news that they only plan one more ocean 'landing' before trying to land on land, is that the next ocean landing attempt (flight #13 - presumably next CRS mission) will have to demonstrate a pinpoint landing. So presumably that will be the first flight with the grid fins installed.Makes sense to demonstrate pinpoint accuracy on the next ocean flight. I think that means a different landing algorithm. More specifically, a predictive controller with the terminal state equality constraints being a one-dimensional set (rotation) instead of a three-dimensional set (rotation + translation).
As for CRS-4 landing's "low probability of success", based on pure speculation, it could be they don't have the enhanced RCS on that flight.
There was some talk about the center core of a FH not being able to return the launch site because it will be too far downrange at staging. Makes me think they’re building a floating platform for landing the center core of the (then safing it and lowering it to horizontal and shipping it back) and they’ll use that for floating recovery of the F9 stage.I read some where that the FH can deliver 7T to GT0 with all 3 boosters recoverable, I think they all stage at same time. At +7T the middle booster will have to do a down range recovery.
Incidentally, here is the Blue Origin patent with the sea going platform:
http://www.google.com/patents/US8678321
There is the possibility that flight 14 will be to a floating "launch" pad and then flight 15 will touchdown on land. With respect to CRS-4 having a low probability of success, is it possible that it could be a repeat of Cassiope, where the rocket spins out of control due to lack of legs?
Bonus: Here is the article saved for posterity: https://web.archive.org/web/20140722210143/http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falcon-9-rocket-first-stage (https://web.archive.org/web/20140722210143/http://www.spacex.com/news/2014/07/22/spacex-soft-lands-falcon-9-rocket-first-stage)
I find it odd they used the words "floating launch pad", when as far as we know, there's not intent to launch an Falcon from a floating platform, is there?
I would think they'd refer to it as a "floating landing pad".
How about an old oil platform. They are perfectly stable.
I'm curious, is this the camera smashing through the inter-stage? ???
I don't really know what this could be other than that.
I don't think you need floating platform to demo "pin point accuracy", just a set of GPS coordinates should be enough to convince the authorities, at most you need a floating beacon, platform is overkill.I am almost certain that the "low probability of success" refers to the low probability that the stage will survive toppling over in the ocean after the soft landing. I am sure they are confident the soft landing and pin point landing itself will work now. I agree that you do not need a floating platform to demo pin point accuracy.
As for CRS-4 landing's "low probability of success", based on pure speculation, it could be they don't have the enhanced RCS on that flight.
How did I miss this yesterday? This news is 18 hours old!
Great to see first video of the retro burn, and audio too! I wonder what the drive flame looks like from the side? A parabolic bow wave?
The video doesn't seem to show any data link drop outs, or any bit flips, or even any visible macroblocks! Is it possible that this was extracted from on-board storage?
No idea.. but it would indeed be nice to know if they followed any of the recommendations from the team here this time around eg. non-interlaced video, etc.
Can anyone confirm this from what has been released - or would you need the full transport stream?
Wow! That icing on the lens didn't obstruct the vision in the way I thought. Given the video cuts off as the vehicle tilts over on the ocean surface, I'd say that's the point the structure failed for whatever reason. Off-axis loads of that kind are obviously more than it could take.How about an old oil platform. They are perfectly stable.
Where's Sea Launch's launch platform right now?
From the update on the SpaceX site:
"We will attempt our next water landing on flight 13 of Falcon 9, but with a low probability of success. Flights 14 and 15 will attempt to land on a solid surface with an improved probability of success."
The real story here is flights 14 & 15 on LAND!! That's before the end of this year.
Does this mean they have gotten precise in hitting a designated landing location?
I wonder if F9R-Dev 2 is going to be needed if they keep collecting data with these flights?
From the same update...
At this point, we are highly confident of being able to land successfully on a floating launch pad or back at the launch site and refly the rocket with no required refurbishment
Or possibly some sort of barge. :o
Maybe rent the Blue Marlin or Black Marlin for a few days. Put some sort of surface on it to protect it, and have it partially submerge (but keep the deck above water) and it shoudl sit pretty stable in the water I'd think.
There may be barges that are cheaper, especially if they were planning to have it land close to shore.
Would a barge pitch too much? Do they have ways of stabilizing them like these heavy lift ships have.
I figure the cheapest, safest option would be an unpowered/towed barge. Just a big hunk of floating metal. A ship would tow the barge out, and then leave the vicinity of the landing area for the safety of the crew.
Due to the height, I'm not sure how practical it would be to move it or lift it using a crane from another ship once it lands, but it would at least prove that the Falcon 9 could land intact at a small target location.
There would also need to be some way to prevent the barge from moving too much (or have the first stage be able to compensate for the barge drifting) and stabilize it enough so it doesn't tip over.
Wow! That icing on the lens didn't obstruct the vision in the way I thought. Given the video cuts off as the vehicle tilts over on the ocean surface, I'd say that's the point the structure failed for whatever reason. Off-axis loads of that kind are obviously more than it could take.How about an old oil platform. They are perfectly stable.
Where's Sea Launch's launch platform right now?
I'm kind of curious how they thought a red hot, or hotter, rocket motor was going to survive immersion in relatively cold sea water? (Cold relative to the motor).
If it didn't immediately explode or distort, I would be VERY suprised. (Wonder if there were any volitiles left in the stage when they cut off the motor. If so, they might have also had a BOOM on their hands).
They probably didn't ever expect the engines to survive the thermal shock...at least not the three used for the re-entry and landing burns.I can see the middle one being hot (and how hot may be up for debate, since it is regeneratively cooled), but the two others should IMHO have cooled off by then. But I am not a rocket scientist. So I might be off with my assumption there.
They probably didn't ever expect the engines to survive the thermal shock...at least not the three used for the re-entry and landing burns.Only one. Three are used for the retro/flyback burn, but only one gets used (several minutes later) for the touchdown burn.
Even if the stages are all flying back to the same point, it is NOT optimal to stage them off all three at once.There was some talk about the center core of a FH not being able to return the launch site because it will be too far downrange at staging. Makes me think they’re building a floating platform for landing the center core of the (then safing it and lowering it to horizontal and shipping it back) and they’ll use that for floating recovery of the F9 stage.I read some where that the FH can deliver 7T to GT0 with all 3 boosters recoverable, I think they all stage at same time. At +7T the middle booster will have to do a down range recovery.
With FH delivering most of GTO payloads we are going to see a lot of FH launches with the boosters being reused multiple times, especially as launches that require a booster/s to be expended will be far and few between.
Originally I expected recovered F9 boosters to be lost on next expendable launch but sounds there may not be any ELV launches for F9.
Even if the stages are all flying back to the same point, it is NOT optimal to stage them off all three at once.
How about an old oil platform. They are perfectly stable.Not many off the East coast :)
With an FH, it's not likely they'll have to be anywhere near optimal. They're talking about using it for payloads an expendable F9 could have handled.Even if the stages are all flying back to the same point, it is NOT optimal to stage them off all three at once.There was some talk about the center core of a FH not being able to return the launch site because it will be too far downrange at staging. Makes me think they’re building a floating platform for landing the center core of the (then safing it and lowering it to horizontal and shipping it back) and they’ll use that for floating recovery of the F9 stage.I read some where that the FH can deliver 7T to GT0 with all 3 boosters recoverable, I think they all stage at same time. At +7T the middle booster will have to do a down range recovery.
With FH delivering most of GTO payloads we are going to see a lot of FH launches with the boosters being reused multiple times, especially as launches that require a booster/s to be expended will be far and few between.
Originally I expected recovered F9 boosters to be lost on next expendable launch but sounds there may not be any ELV launches for F9.
The only time they ever thought of reusing after splashdowns was when it was a pure parachute re-entry, and all engines would have been cool. That went away before the F9 even flew, when the F1s did so poorly after hitting the water.They probably didn't ever expect the engines to survive the thermal shock...at least not the three used for the re-entry and landing burns.I can see the middle one being hot (and how hot may be up for debate, since it is regeneratively cooled), but the two others should IMHO have cooled off by then. But I am not a rocket scientist. So I might be off with my assumption there.
It would be a completely different process. And NO, the dirt and ice is not static, even if it would appear that way.
Incidentally, here is the Blue Origin patent with the sea going platform:
http://www.google.com/patents/US8678321
Granted March 25, 2014!
That's news.
This is such a silly patent (and I'm surprised someone hadn't patented it already years ago; maybe someone has and it's just lost in the archives). Is Blue Origin going to enforce it? Or is it just one of those safe patents to keep someone else from stopping you...
Regardless since SpaceX is in the R&D phase any efforts landing on a floating platform will be exempt.
The patent will likely be invalidated by prior art. See for example The Rocket Company, page 52 (AIAA, published 2005). I also proposed both launch and landing from a floating platform in 1998, and while I didn't specify using a rocket, that is "obvious to one skilled in the art."
Thus I believe SpaceX could certainly attempt a platform recovery on a upcoming flight.
I wonder why while this one has ice, previous one didn't?trajectory mostly, this stage had a much steeper trajectory then CRS-3 hence the Ice
I wonder why while this one has ice, previous one didn't?trajectory mostly, this stage had a much steeper trajectory then CRS-3 hence the Ice
So, no external video? <Groan>. What about the video from the NASA plane which filmed the hypersonic “re-entry”?
Chill down.
Anyway, FWIW, I don't think they'll put it up (if they have it in the first place). As far as SpaceX is concerned, the splashdown concluded their mission. So there's nothing beyond that which they'd need to include in the summary.
The patent will likely be invalidated by prior art. See for example The Rocket Company, page 52 (AIAA, published 2005). I also proposed both launch and landing from a floating platform in 1998, and while I didn't specify using a rocket, that is "obvious to one skilled in the art."
Thus I believe SpaceX could certainly attempt a platform recovery on a upcoming flight.
Conceivably the ship could be prepositioned down range so you could land the stage on it.
The patent will likely be invalidated by prior art. See for example The Rocket Company, page 52 (AIAA, published 2005). I also proposed both launch and landing from a floating platform in 1998, and while I didn't specify using a rocket, that is "obvious to one skilled in the art."
Thus I believe SpaceX could certainly attempt a platform recovery on a upcoming flight.
I found the Amazon link for The Rocket Company, and was able to reach page 52. (http://www.amazon.com/The-Rocket-Company-Library-Flight/dp/1563476967#reader_1563476967)QuoteConceivably the ship could be prepositioned down range so you could land the stage on it.
The patent will likely be invalidated by prior art. See for example The Rocket Company, page 52 (AIAA, published 2005). I also proposed both launch and landing from a floating platform in 1998, and while I didn't specify using a rocket, that is "obvious to one skilled in the art."
Thus I believe SpaceX could certainly attempt a platform recovery on a upcoming flight.
I found the Amazon link for The Rocket Company, and was able to reach page 52. (http://www.amazon.com/The-Rocket-Company-Library-Flight/dp/1563476967#reader_1563476967)QuoteConceivably the ship could be prepositioned down range so you could land the stage on it.
I'm really disappointed to see HMXHMX propagating the myth that patents cover ideas and the mere prior mention of the broad concept, or even a similar concept, can somehow invalidate a patent. By this logic 8,690,104 (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8690104.PN.&OS=PN/8690104&RS=PN/8690104) is invalid because Stardust is prior art.
Just leave the lawyerin' to the lawyers, eh? or Bezos and Musk can work out a deal over golf and canapes.
I did leave the lawyering to the lawyers. I asked my patent attorney for his opinion prior to posting.
I did leave the lawyering to the lawyers. I asked my patent attorney for his opinion prior to posting.
Heh, did he give you that horrible attempt at prior art too? How much did he charge you to read the patent?
Nothing. He used to work for me and wrote the book.
Why the fax machine is nothing but a waffle iron with a phone attached!
Repairing the CRS-3 landing was restoring a painting that had been put through a shredder. Repairing this video would be trying to restore a painting where the painter was constantly being interrupted by a toddler drawing all over their canvas as they were working.
One tidbit I just noticed. If you replay the landing video and take the timestamps just before and after the middle fadeout (between the retro burn and the landing burn), you see 15:24:17 and 15:25:39, or only one minute and 22 seconds. That's a mighty short time period, which implies that the retro burn is occurring at a much lower altitude than I (at least) would expect. Even if the rocket were still descending at 1000mph after completion of the retro burn, and averaged around 700 mph during the descent (faster at higher altitudes, slower near the end due to thickening air), that works out to only about 15 miles or so.
I am not a rocket scientist, nor an aeronautical engineer. If my napkin calculation is wrong, please explain.
I think (I don't know) that they skipped the boostback burn altogether on this flight. So the stage separation and reorientation would have occurred at about the three minute mark, followed by a controlled drift (keeping the stage orientation steady with RCS) for twelve whole minutes, arcing up, and then down. The reentry burn would have occurred soon after atmospheric drag started to make itself felt.One tidbit I just noticed. If you replay the landing video and take the timestamps just before and after the middle fadeout (between the retro burn and the landing burn), you see 15:24:17 and 15:25:39, or only one minute and 22 seconds. That's a mighty short time period, which implies that the retro burn is occurring at a much lower altitude than I (at least) would expect. Even if the rocket were still descending at 1000mph after completion of the retro burn, and averaged around 700 mph during the descent (faster at higher altitudes, slower near the end due to thickening air), that works out to only about 15 miles or so.
I am not a rocket scientist, nor an aeronautical engineer. If my napkin calculation is wrong, please explain.
I think the real question is: what was the timestamp of stage separation? We know there was some RCS maneuvering immediately after sep. Did the retro burn immediately follow that, or did they allow themselves to "drift" downrange? (And if they were targetting RTLS, would they have drifted, or done the burn right away?)
I did leave the lawyering to the lawyers. I asked my patent attorney for his opinion prior to posting.Heh, did he give you that horrible attempt at prior art too? How much did he charge you to read the patent?
Nothing. He used to work for me and wrote the book. There are numerous other examples of prior art, none of which are quoted by the patent. It is utterly indefensible on several grounds – and I do know something about the prior art here.
But we are straying too far off topic.
1. So, no external video? <Groan>. What about the video from the NASA plane which filmed the hypersonic “re-entry”?I agree that I'm hoping to see this at some point. But I don't think SpaceX "owes it to me".
Come to think of it, you don't even need a surface ship in order to get video. [...] Get a few quad-copters on a submarineRadio waves don't propagate underwater. (Except for VLF.)
2. Did they do any boost-back on this flight? Anyone know the co-ordinates of the splashdown?The nautical keep out area was posted (I'm too lazy to look it up, it might have been in L2) and it was indeed significantly closer to shore than on the previous flight. We also had real time flight tracking of the various aircraft involved in observing the flight, and the area they were canvassing was consistent with the keep out area. That's in the public thread, you can go find it.
Wouldn't they want to demonstrate that they could fly the F9 S1, precisely, and using the same mass-vs-time profile as an S1 that had to carry prop reserve for boost-back?
That suggests to me that that the next one will travel a significant distance cross-range (instead of boost-back), and that perhaps there's some uninhabited area (as opposed to the relatively densely populated Space Coast?) that SpaceX can touch down on.
3. Plus, I think they'd have to demonstrate more than pin-point landing accuracy.
(EDIT: Couldn't all three S1 cores separate at the same time? [...])That would defeat the point. FH is a three-stage rocket. The two boosters are the first stage. Getting rid of a stage has a large negative impact on performance; study the rocket equation.
4. I don't understand why a floating platform would be uneconomical.
I think (I don't know) that they skipped the boostback burn altogether on this flight. So the stage separation and reorientation would have occurred at about the three minute mark, followed by a controlled drift (keeping the stage orientation steady with RCS) for twelve whole minutes, arcing up, and then down. The reentry burn would have occurred soon after atmospheric drag started to make itself felt.One tidbit I just noticed. If you replay the landing video and take the timestamps just before and after the middle fadeout (between the retro burn and the landing burn), you see 15:24:17 and 15:25:39, or only one minute and 22 seconds. That's a mighty short time period, which implies that the retro burn is occurring at a much lower altitude than I (at least) would expect. Even if the rocket were still descending at 1000mph after completion of the retro burn, and averaged around 700 mph during the descent (faster at higher altitudes, slower near the end due to thickening air), that works out to only about 15 miles or so.
I am not a rocket scientist, nor an aeronautical engineer. If my napkin calculation is wrong, please explain.
I think the real question is: what was the timestamp of stage separation? We know there was some RCS maneuvering immediately after sep. Did the retro burn immediately follow that, or did they allow themselves to "drift" downrange? (And if they were targetting RTLS, would they have drifted, or done the burn right away?)
Looking back at the launch videos (presumably the same clock and same camera), the timer at stage separation was approximately 15:17:50. So retro burn was about 6:30 afterwards.
Both readings are approximate, since the timer at stage separation was hard to read (white on white), and when we see the retro burn, it had already started.
Wasn't this a more lofted trajectory than normal? Is it possible they didn't need a large boost-back because the first stage went higher and less downrange than previous?Frankly, I'm not sure they did any boostback at all. They ran one seriously lofted trajectory this time.
1 minute and 22 seconds at terminal velocity is not much at all.
The flight radar track shows that F900 was 336 km downrange from the pad. [...] I'll have to run the numbers, but that seems pretty close to a ballistic trajectory.If it's a ballistic trajectory and the closer return was due solely to the lofted launch, then most of my reasoning above is bogus. Oh, well.
time alt speed range note
km mps km
launch video
15:14:30 0 0 0
+1:00 13 450 2.5
+2:20 54 1400 21
+2:25 40 sep
+2:40 112 1700 51 MVAC
+4:30 240 1800 130 NewHampshire
+5:30 334 2200 209
+6:30 420 2700 305
+7:30 511 3600 460
+8:45 600 5700 150???
+9:30 620 7200 1000 2ndStage cutoff
landing video
+9:13 start of music
+9:23 ? ? ? retro burn
+9:49 ice
+11:09 ? ? ? oceanvisible
+11:12 ? ? ? landing RCS
+11:20 ? ? ? roll stopped
+11:27 ? ? ? legs
+11:33 ? ? ? full plume
+11:36 ? 0 330 engine out
+11:39 ? 0 330 splash subsides
+11:41 ? 0 330 start tipover
+11:43 ? 0 330 kaboom
+11:12 landing RCS
On the video this is titled "landing burn".I don't believe the wording in the video, at least not precisely. Obviously an engine is burning. But there is a big difference in the flame size at +11:12 vs +11:33 , and the earlier one has a pulsating pattern.
We knew the boost-back burn uses 3 (from the video, and it's clear you need to turn back as fast as possible, and the stage is still heavy) and we knew the landing burn uses 1 (empty stage, hover-slam) but the secret-sauce burn is a little less secret now. We know when it occurs, and we know it uses 3 engines.
A reddit user TheVehicleDestroyer ran the numbers more than a week ago. The best fit for the available data is a ballistic trajectory from separation. No boostback.The video does look like 3 engines are burning, at least at time Separation+6:00. However, we don't know how long it burned. It also seems clear that it was not a 'boost-back', since range kept increasing.
On the video this is titled "landing burn".I don't believe the wording in the video, at least not precisely. Obviously an engine is burning. But there is a big difference in the flame size at +11:12 vs +11:33 , and the earlier one has a pulsating pattern.
Also, time to decelerate from terminal velocity to hover is T = V * a where a = m / (F-W) = 1/(F/m - g) => T = V/(F/m - g) . Guesses of V=100m/s, F = 600 kN, m = 18000 kg yields deceleration of 30g and firing time of 3 seconds, which is consistent with my parsing of the video. However, the video label "landing burn" occurs 24 seconds before splashdown.
I don't think you need a quadcopter when you have Elon's personal jet in the area.
We don't know what other free variables were specified on this landing attempt.
...
These landing attempts are about supersonic retropropulsion and reentry heating on the structure, which is the flight regime F9R can't easily test. (Propellant quantities can be computed, they don't need a test flight for that.)
Crazy talk. The progression between cassiope, CRS-3 and ORBCOMM flight has been landing closer to shore each time.
That would defeat the point. FH is a three-stage rocket. The two boosters are the first stage. Getting rid of a stage has a large negative impact on performance; study the rocket equation.
...Economics is pretty pliable. It hasn't been too long ago since the days when discussions of cheap re-usability itself was heresy; yet here SpaceX are...makingattempting to make the economics work.
On the video this is titled "landing burn".I don't believe the wording in the video, at least not precisely. Obviously an engine is burning. But there is a big difference in the flame size at +11:12 vs +11:33 , and the earlier one has a pulsating pattern.
It hasn't been too long ago since the days when discussions of cheap re-usability itself was heresy; yet here SpaceX are... making the economics work.Nope. They are in progress of making it work technically.
At this point, we are highly confident of being able to land successfully [..] and refly the rocket with no required refurbishment.
Quote from: SpaceXAt this point, we are highly confident of being able to land successfully [..] and refly the rocket with no required refurbishment.
I don't know how they can make any claims about refurbishment if they haven't recovered a stage yet.
What's that got to do with anything? It's the reentry that does the damage (if any).On the contrary, launch and landing are probably harder on the vehicle than a few Mach reentry. Or at least, SpaceX likely believe so.
What's that got to do with anything? It's the reentry that does the damage (if any).On the contrary, launch and landing are probably harder on the vehicle than a few Mach reentry. Or at least, SpaceX likely believe so.
We're talking about SpaceX, here. BFR, Mars Colony of a million people who pay just $500,000 SpaceX. They know it doesn't blow up until it topples over. That's better proof of not being beat up than anything they have about a Mars colony.What's that got to do with anything? It's the reentry that does the damage (if any).On the contrary, launch and landing are probably harder on the vehicle than a few Mach reentry. Or at least, SpaceX likely believe so.
I'm not arguing that. The point is they can't possibly know that yet. Until they recover a stage, they won't know how beaten up it is.
They are claiming they are confident, not that they know it for a fact. They don't have the stage but they have the telemetry and whatever simulations they've run. They have a fair idea the stresses the stage encountered on reentry and they know everything was functioning as they expected.Quote from: SpaceXAt this point, we are highly confident of being able to land successfully [..] and refly the rocket with no required refurbishment.
I don't know how they can make any claims about refurbishment if they haven't recovered a stage yet.
They are claiming they are confident, not that they know it for a fact. They don't have the stage but they have the telemetry and whatever simulations they've run. They have a fair idea the stresses stage encountered on reentry and they know everything was functioning as they expected.Quote from: SpaceXAt this point, we are highly confident of being able to land successfully [..] and refly the rocket with no required refurbishment.
I don't know how they can make any claims about refurbishment if they haven't recovered a stage yet.
When they recover one, especially if they land one, then they'll know for a fact. Maybe it will turn out they are wrong, but I can't see the problem with being them saying they are confident at this point.
When's the last time SpaceX wasn't highly confident about something? That's sort of their defining trait isn't it? :)
That's certainly better than nothing, but I don't think it's sufficient for the claim they've made here. They need to recover the stage.
I'm still wondering why we haven't seen any surface video of the return.
I was probably too wordy in my earlier post to encourage replies (http://forum.nasaspaceflight.com/index.php?topic=35243.msg1232564#msg1232564), but I did want to make the point that any future recovery of the second stage in flights from the Cape to LEO would likely have to be on a ship-based platform off Western Australia (as opposed to a land-based platform). Therefore, experience recovering the first stage on a ship-based platform will be useful, even if the eventual plan is to bring first stages back to the pad. I'm looking forward to flights 14 & 15 :)
This post does come to the topic - bear with me :)
I know I saw somewhere (maybe for CRS-3) an exclusion zone map for the second stage coming down off the coast of Western Australia. Being a resident of Perth WA, I began wondering if SpaceX is likely to attempt to build landing pad(s) somewhere near me, (or maybe if it will be more efficient to give the second stage just enough of an extra boost so it comes down somewhere near Florida after the first full orbit)
Any second stages returning to land on current trajectories would have to come down somewhere on the WA coast....
This post does come to the topic - bear with me :)
I know I saw somewhere (maybe for CRS-3) an exclusion zone map for the second stage coming down off the coast of Western Australia. Being a resident of Perth WA, I began wondering if SpaceX is likely to attempt to build landing pad(s) somewhere near me, (or maybe if it will be more efficient to give the second stage just enough of an extra boost so it comes down somewhere near Florida after the first full orbit)
Any second stages returning to land on current trajectories would have to come down somewhere on the WA coast....
No they wouldn't. Just because SpaceX chose to de-orbit the second stage in that area for this flight doesn't mean a future re-usable stage would do that. Why would they ever chose to bring the stage down in an area which has the maximum distance to transport the stage home? Bear in mind a recoverable second stage is a spacecraft. It essentially has to do what Dragon has to do for re-entry and landing. Why would they consider landing the stage on a platform at sea (extra cost and complexity of operations) when they can land it anywhere on land between the latitudes of the orbital inclination?
But I notice we're getting OT here and I'm contributing to it. I shall reprimand myself and say no more!
I'm still wondering why we haven't seen any surface video of the return. They show surface video of the Dragon returns after all and surface video goes a long way toward proving that they know where it will touch down. Video shot from aircraft is good, (Casiope) but one could argue that an airplane could move several miles toward the touch down while the stage is returning. A boat can't move far at all during the return.
I'm still wondering why we haven't seen any surface video of the return. They show surface video of the Dragon returns after all and surface video goes a long way toward proving that they know where it will touch down. Video shot from aircraft is good, (Casiope) but one could argue that an airplane could move several miles toward the touch down while the stage is returning. A boat can't move far at all during the return.
The NASA crew failed to obtain video: it was too hard to track the rocket. They will reportedly try again for CRS-4. There might be other video, but remember this is only the *first* shot they've had at capturing landing video -- the CRS-3 flight has terrible weather, so they didn't even get to try then. Yes, we have good surface video of Dragon now --- but there have been five Dragons. I seem to recall the first dragon didn't have great surface splashdown photos either. And remember that parachute landings are quite leisurely compared to the propulsive landing process.
Considering SpaceX's lawsuit against the Air Force, I guess it's very unlikely they'll agree to allowing the use of their RC-135S Cobra Ball to observe/video the booster return, even if it was available...this is their regular job...
Considering SpaceX's lawsuit against the Air Force, I guess it's very unlikely they'll agree to allowing the use of their RC-135S Cobra Ball to observe/video the booster return, even if it was available...this is their regular job...
"It’s not as though we’re battling the whole Air Force. That’s not the case at all. I think we’re on very good terms with the vast majority of the Air Force. Our concern really relates to a handful of people in the procurement area of the Air Force.”
Looking at the video, I was surprised at how late the landing legs deployed.<snip>I've read a few comments about timing of the legs, and consistency with the CRS-3 landing. So I decided to do a split screen video on both landings and watch them side by side - and this lead to me adding one thing after another until my wife said I've spent too much time on this.
Looking at the video, I was surprised at how late the landing legs deployed.<snip>I've read a few comments about timing of the legs, and consistency with the CRS-3 landing. So I decided to do a split screen video on both landings and watch them side by side - and this lead to me adding one thing after another until my wife said I've spent too much time on this.
So here's a link to my 2 minute combination of 5 videos showing the reusability of the first stage. :)
I've read a few comments about timing of the legs, and consistency with the CRS-3 landing. So I decided to do a split screen video on both landings and watch them side by side - and this lead to me adding one thing after another until my wife said I've spent too much time on this.
So here's a link to my 2 minute combination of 5 videos showing the reusability of the first stage. :)
Great video. Thanks. So the legs deploy in parallel.
Looking at the video, I was surprised at how late the landing legs deployed.<snip>I've read a few comments about timing of the legs, and consistency with the CRS-3 landing. So I decided to do a split screen video on both landings and watch them side by side - and this lead to me adding one thing after another until my wife said I've spent too much time on this.
So here's a link to my 2 minute combination of 5 videos showing the reusability of the first stage. :)
Very good comparison.Yes I was wondering about the same things.
What I see: the last part of the landing, while the engine blows the dust/vapor away has other length at the test flights and at the ocean landings:
- 1:49-1:52 at ocean landings
- 1:49-1:57 at F9R landings
Maybe the landing speed is higher (this is my guess as explanation) at ocean landing? More aggressive deceleration in this case? Or the engine was shut down earlier because of the water?
I tried to measure the velocity of objects on the video before 1:49. The waves at CRS-3 seems to be more speedy going away from the rocket, than the object on the F9R videos, but I don't know if the video restoring was enough accurate to use for this measurement.I would say that at the beginning of the F9R descent in the video, it's moving more slowly (much more slowly?) than the water landings. By the time they reach ground/water level they all seem to move equally slowly.
A long enough reentry burn is the same as a reentry burn... There's not a sharp line, there. :)
Great vid! The only minor critique I have is that we're pretty sure that there wasn't a boost-back, just re-entry and landing burns. So, if I was making this video (I'm in no way skilled enough to make one anywhere near as good as your is though), I don't think I would show one even in animation. But this is a fairly minor technical point. Great job!Thanks Deruch :)
I haven't been paying much attention to it lately, but in the CRS-3 video interpretation thread (http://forum.nasaspaceflight.com/index.php?topic=34794.msg1227591#msg1227591), user sittingduck is working on creating an accurate animation of the CRS-3 booster landing. You might be interested in the final product. I'm not sure how far along it is though.Great vid! The only minor critique I have is that we're pretty sure that there wasn't a boost-back, just re-entry and landing burns. So, if I was making this video (I'm in no way skilled enough to make one anywhere near as good as your is though), I don't think I would show one even in animation. But this is a fairly minor technical point. Great job!Thanks Deruch :)
I also though about that... as well as the animation of the rocket descending and legs opening while still at quite an altitude - when it seems that the actual attempts have opened much lower(?). I think reusability plans have evolved in the last 2 years (the animation still has the square layout of engines too).
I wasn't trying to emulate the 2 'land'ings so much as give a good story of the overall process we're seeing developed. It was partly a "side by side" of the 2 successful attempts, and partly an upgrade to the animation via as much real footage as possible - because both of the supplied videos have weaknesses. They're not clear, and too easy for the casual viewer to misinterpret the landing videos as having the engines ignite only at the last second. In the side-by-side I wanted to show the common leg movements, matching flames, and the similar flame activity in the F9R when near real ground (with a linking wide shot for some perspective).
But yeah... the purist in me wants to keep it entirely consistent with the OG2!
Anyone know if they are going to do a hover / translation on any of the upcoming flights. (ie, hover then start translating towards the coast.) It seems like that would be a logical step in the test plan. I suppose they would have to do something like this prior to coming onshore to land at the Cape since a boost IIP on the land would be scary. It would be really cool to see!I agree it would be cool to see, but hover isn't going to happen on any real flight, because to do that they would have to have enough fuel left over in the rocket to where the T/W ratio is one or less when throttled down to 60%. The only reason the Grasshopper and F9R-Dev1 rockets have been able to hover is because they are ballasted with much more fuel than would be present on a real return from launch.
Anyone know if they are going to do a hover / translation on any of the upcoming flights. (ie, hover then start translating towards the coast.) It seems like that would be a logical step in the test plan. I suppose they would have to do something like this prior to coming onshore to land at the Cape since a boost IIP on the land would be scary. It would be really cool to see!I agree it would be cool to see, but hover isn't going to happen on any real flight, because to do that they would have to have enough fuel left over in the rocket to where the T/W ratio is one or less when throttled down to 60%. The only reason the Grasshopper and F9R-Dev1 rockets have been able to hover is because they are ballasted with much more fuel than would be present on a real return from launch.
Translation may occur, to a small extent, during the landing burn. Grid fins should have the effect of minimizing this.
I disagree. I thought that was why they were choosing a pad next to the ocean- the return will target a patch of water 200-400 meters offshore and the rocket will use the landing burn to translate to the pad.I didn't say translation would not occur, only that it would be minimal. There's only so much translation you can do when your entire burn lasts only about 24 seconds. And there will be no hovering . . . unless Mueller and his staff manage pull a rabbit out of a hat and suddenly discover how to get a Merlin 1D to throttle down more than 50%.
Otherwise they risk damage to the pad. Bare concrete pads still cost a significant amount of money.
Anyone know if they are going to do a hover / translation on any of the upcoming flights. (ie, hover then start translating towards the coast.) It seems like that would be a logical step in the test plan. I suppose they would have to do something like this prior to coming onshore to land at the Cape since a boost IIP on the land would be scary. It would be really cool to see!
unless Mueller and his staff manage pull a rabbit out of a hat and suddenly discover how to get a Merlin 1D to throttle down more than 50%.Wasn't that confirmed already at some point? I distinctly remember a quote from Musk about the surprisingly large throttle range of the Merlin 1D (anyone here who can dig it up?).
Yet another rabbit, that is.
Wasn't that confirmed already at some point? I distinctly remember a quote from Musk about the surprisingly large throttle range of the Merlin 1D (anyone here who can dig it up?).
Wasn't that confirmed already at some point? I distinctly remember a quote from Musk about the surprisingly large throttle range of the Merlin 1D (anyone here who can dig it up?).
If I recall correctly, it was a twitter quote that was much debated. IIRC he said "60% throttle" or some such, and readers were sharply divided over whether he meant "throttle down 60%" (aka, total thrust 40% of maximum) -- which would be surprising -- or "total thrust of 60% of maximum", which would be less surprising.
Evidence since then has not supported the surprising interpretation.
What would be acceptable vertical velocity limits for "hovering"? 0 +/- 5 m/s? Can the stage do that by pulsing the engines, or even by slewing the throttle up and down constantly? If the response time of the engine, and the rates are fast enough, then you wouldn't need the T/W to be ~= 1 at all. (Although, obviously that does help).
Basically, can they playing a game of flappy bird, with a Falcon?
What would be acceptable vertical velocity limits for "hovering"? 0 +/- 5 m/s? Can the stage do that by pulsing the engines, or even by slewing the throttle up and down constantly? If the response time of the engine, and the rates are fast enough, then you wouldn't need the T/W to be ~= 1 at all. (Although, obviously that does help).
Basically, can they playing a game of flappy bird, with a Falcon?
No, because of instabilities with the prop in the engine. Basically the same reason they can't throttle down beyond a certain point- because the propellant has to mix and combust at a certain rate and if it doesn't you might get too little combustion for a brief moment, then a spike in pressure as the buildup of uncombusted, poorly mixed propellant finally combusts. And there goes your engine.
I think the dracos can pulse because their fuel is hypergolic.
I think the dracos can pulse because their fuel is hypergolic.
There's a big difference between opening and closing a valve and spinning up turbo pumps.I think the dracos can pulse because their fuel is hypergolic.
I thought it was because they were pressure fed... much easier to smoothly change the throttle than a pump-fed system. Or maybe it is both...
There's a big difference between opening and closing a valve and spinning up turbo pumps.I think the dracos can pulse because their fuel is hypergolic.
I thought it was because they were pressure fed... much easier to smoothly change the throttle than a pump-fed system. Or maybe it is both...
I believe that's the case with closed cycle TP, but on an open cycle, like that Gas Generator, couldn't you just put a throttling valve between the TP pump and the injectors and simply restrict flow while reducing the gg gas flow?There's a big difference between opening and closing a valve and spinning up turbo pumps.I think the dracos can pulse because their fuel is hypergolic.
I thought it was because they were pressure fed... much easier to smoothly change the throttle than a pump-fed system. Or maybe it is both...
Yes, that's exactly the point he was making. If you want a responsive thruster able to pulse rapidly, it has to be pressure fed. No matter if the propellant is hypergolic or cryogenic.
I believe that's the case with closed cycle TP, but on an open cycle, like that Gas Generator, couldn't you just put a throttling valve between the TP pump and the injectors and simply restrict flow while reducing the gg gas flow?There's a big difference between opening and closing a valve and spinning up turbo pumps.I think the dracos can pulse because their fuel is hypergolic.
I thought it was because they were pressure fed... much easier to smoothly change the throttle than a pump-fed system. Or maybe it is both...
Yes, that's exactly the point he was making. If you want a responsive thruster able to pulse rapidly, it has to be pressure fed. No matter if the propellant is hypergolic or cryogenic.
I believe that's the case with closed cycle TP, but on an open cycle, like that Gas Generator, couldn't you just put a throttling valve between the TP pump and the injectors and simply restrict flow while reducing the gg gas flow?
That's essentially what you do with face throttling. You have to avoid pump stall, but that just means throttling the GG, which is how the Merlin apparently does it.
http://jasc-controls.com/jasc-industry-listing/space/space-fluid-management/bi-propellant-valve/ (http://jasc-controls.com/jasc-industry-listing/space/space-fluid-management/bi-propellant-valve/)
I believe that's the case with closed cycle TP, but on an open cycle, like that Gas Generator, couldn't you just put a throttling valve between the TP pump and the injectors and simply restrict flow while reducing the gg gas flow?
That's essentially what you do with face throttling. You have to avoid pump stall, but that just means throttling the GG, which is how the Merlin apparently does it.
http://jasc-controls.com/jasc-industry-listing/space/space-fluid-management/bi-propellant-valve/ (http://jasc-controls.com/jasc-industry-listing/space/space-fluid-management/bi-propellant-valve/)
Why would you need to throttle the GG at all? Split the flow downstream of the main fuel valve (http://blogs.nasa.gov/wp-content/uploads/sites/212/2013/06/1035780main_gasgenerat6r.jpg) (and/or the main oxidiser valve), prior to the injector, and add a second flow path back to the tank, controlled by a valve. Now, if this back-to-tank valve is fully closed, the engine operates as it did previously. If it's open, then the pressurised fuel/oxidiser that exits the turbo-pump simply makes its way back to the tank instead of the combustion chamber.
You wouldn't get rid of the combustion stability, and transition forces issues that would be introduced by pulsing/rapid deep-throttling, but you would - in my head atleast - be able to throttle the engine, without needing to change the speed of the turbo-pumps, or throttling the gas generator.
There would be new problems of course. One I can think of is with respect to maintaining the back-to-tank flow path at cryogenic temperatures - in case of the LOX, as well as avoiding getting filler gas bubbles flowing back into the pipe etc. You could do it only on the fuel side, but that would mean that whenever you throttled down, you'd be burning oxidiser-rich, and probably a lot hotter than the design of the nozzle/combustion chamber was designed to cope with.
I believe that's the case with closed cycle TP, but on an open cycle, like that Gas Generator, couldn't you just put a throttling valve between the TP pump and the injectors and simply restrict flow while reducing the gg gas flow?There's a big difference between opening and closing a valve and spinning up turbo pumps.I think the dracos can pulse because their fuel is hypergolic.
I thought it was because they were pressure fed... much easier to smoothly change the throttle than a pump-fed system. Or maybe it is both...
Yes, that's exactly the point he was making. If you want a responsive thruster able to pulse rapidly, it has to be pressure fed. No matter if the propellant is hypergolic or cryogenic.
That's essentially what you do with face throttling. You have to avoid pump stall, but that just means throttling the GG, which is how the Merlin apparently does it.
http://jasc-controls.com/jasc-industry-listing/space/space-fluid-management/bi-propellant-valve/
LOX @ +100F! Wasn't expecting that. ;-)Question for the real rocket scientists around here: If this valve claims to tolerate LOX at 100 degrees Fahrenheit, then what is the state of the "liquid" oxygen then? Gaseous, or pressure-induced liquid?
I presume, then, that it's not especially easy to run a GG on its own, without actually firing the engine attached to it? Just that if you could, it would open up possibilities for very low thrust for manoeuvring and landing burns...GG exhaust is low pressure, low velocity, so you aren't going to get useful thrust out of it. If you changed that, you'd just make it less efficient at powering the pumps.
LOX @ +100F! Wasn't expecting that. ;-)Question for the real rocket scientists around here: If this valve claims to tolerate LOX at 100 degrees Fahrenheit, then what is the state of the "liquid" oxygen then? Gaseous, or pressure-induced liquid?
I presume, then, that it's not especially easy to run a GG on its own, without actually firing the engine attached to it? Just that if you could, it would open up possibilities for very low thrust for manoeuvring and landing burns...GG exhaust is low pressure, low velocity, so you aren't going to get useful thrust out of it. If you changed that, you'd just make it less efficient at powering the pumps.
LOX @ +100F! Wasn't expecting that. ;-)Question for the real rocket scientists around here: If this valve claims to tolerate LOX at 100 degrees Fahrenheit, then what is the state of the "liquid" oxygen then? Gaseous, or pressure-induced liquid?
I have no idea why they wrote that into the spec. Perhaps someone else does?
Only when it's pumping fuel to the main engines. If you tried to do that without an equivalent load on the turbopump you'd just blow it up from overspeed. Thrust isn't linear with respect to throttle, most of it comes at the very end, when the flow is restricted enough by the throat of the nozzle that your chamber pressure and exhaust velocity climb. Think of the combustion chamber like a balloon. If you let the gasses through a narrow constriction, they go fast, and in one direction, so you get thrust. If you let the gasses go anywhere without restriction, you get very little thrust, like a campfire.I presume, then, that it's not especially easy to run a GG on its own, without actually firing the engine attached to it? Just that if you could, it would open up possibilities for very low thrust for manoeuvring and landing burns...GG exhaust is low pressure, low velocity, so you aren't going to get useful thrust out of it. If you changed that, you'd just make it less efficient at powering the pumps.
Depends on your definition of "useful." The 1.5E6-lbf F-1 generates 40K-lbf thrust with its GG exhaust after spinning the turbine and being used as a heat exchanger fluid.
LOX @ +100F! Wasn't expecting that. ;-)Question for the real rocket scientists around here: If this valve claims to tolerate LOX at 100 degrees Fahrenheit, then what is the state of the "liquid" oxygen then? Gaseous, or pressure-induced liquid?
I have no idea why they wrote that into the spec. Perhaps someone else does?
LOX @ +100F! Wasn't expecting that. ;-)Question for the real rocket scientists around here: If this valve claims to tolerate LOX at 100 degrees Fahrenheit, then what is the state of the "liquid" oxygen then? Gaseous, or pressure-induced liquid?
Hey Chris,Having watched this 20 times already, at least half of them before I picked my jaw up off the desk, I concur with this request.
Since this is a video of a video, has the original been released.
Assume it has better detail and additional content...
Hey Chris,
Since this is a video of a video, has the original been released.
Assume it has better detail and additional content...
It is really hard to see in the video, but does it seem like the stage is not completely straight upright when by the time the video cuts out?
Hey Chris,
Since this is a video of a video, has the original been released.
Assume it has better detail and additional content...
SpaceX will be the ones to do that as noted in my post. Really looking forward to that!
It seems the camera switches between infrared and normal visual at around 16-17 seconds mark as it looks like a continuous shot you can make out a blurry falling object before the switch and no sign of lit up engines in those and after that we go directly to splashdown.
There's something to be learned from this video, when comparing it to the CASSIOPE "3 meter" picture (below).
There was discussion back then on whether the engine "really fired" or whether it just "burped" and SpaceX was misrepresenting it as a "prematurely terminated firing" or some such. (The usual conspiracy theories)
In that CASSIOPE picture, the smoke/vapor doughnut is well formed, and the engine is already off.
In this video, we see that the engine ignites rather early, and fires for a pretty good duration before the doughnut forms, and surface contact occurs only 2-3 seconds after the doughnut forms.
The conclusion is that CASSIOPE ignited and had a nice controlled burn before the engines starved - otherwise the supposed "burp episode" would have occurred too high to form the doughnut.
There's something to be learned from this video, when comparing it to the CASSIOPE "3 meter" picture (below).
There was discussion back then on whether the engine "really fired" or whether it just "burped" and SpaceX was misrepresenting it as a "prematurely terminated firing" or some such. (The usual conspiracy theories)
In that CASSIOPE picture, the smoke/vapor doughnut is well formed, and the engine is already off.
In this video, we see that the engine ignites rather early, and fires for a pretty good duration before the doughnut forms, and surface contact occurs only 2-3 seconds after the doughnut forms.
The conclusion is that CASSIOPE ignited and had a nice controlled burn before the engines starved - otherwise the supposed "burp episode" would have occurred too high to form the doughnut.
That's what I've long thought looking at the CASSIOPE photo. I'd heard talk from a SpaceXer that they came "very close" to a soft landing. Its obvious they got slow and within a stage length of the water before it went a bit pear shaped.
@jeff_foust 12 min.
Jurvetson said the video had been shot from aircraft, though a glitch caused the vehicle to go out of frame around touchdown. #smallsat2014
Looks like this is the PG-13 version - the camera fades out before the shocking and graphic RUD.
Talk about coming in hot! She's really moving.Moving, but decelerating too and under control, which all makes this such an usual sight. I also suspect that camera movement may have made the stage appear to be moving faster than it really was when it broke through the clouds.
As for the question of whether or not this particular video cameraman simply messed up and missed the final result, that I think is beside the point. SpaceX, surely, has better engineering video of the entire event. Perhaps it will release the original of this one that conveniently misses the end. Perhaps not. But I doubt it will release the fully detailed video or videos that show everything.Ed, they've released segments or stills from a video of this quality twice, both times stated to be from a plane in the area. My suspicion is that this is the engineering video from the plane, just as CASSIOPE was, and that they simply mis-timed some camera motion, not some conspiracy to "hide" the end of the video. I mean...we've seen what the reception did to the video from CRS-3, and the ice on OrbComm. Even people who can bring a rocket down from orbit are occasionally limited by the systems they have set up to document it.
Ed, they've released segments or stills from a video of this quality twice, both times stated to be from a plane in the area. My suspicion is that this is the engineering video from the plane, just as CASSIOPE was, and that they simply mis-timed some camera motion, not some conspiracy to "hide" the end of the video. I mean...we've seen what the reception did to the video from CRS-3, and the ice on OrbComm. Even people who can bring a rocket down from orbit are occasionally limited by the systems they have set up to document it.The future path of this entire company depends on the results of this breakthrough testing - testing that costs a good bit of money. Do you really believe that SpaceX is depending on only one hand-held camera to capture the results?
Ed, they've released segments or stills from a video of this quality twice, both times stated to be from a plane in the area. My suspicion is that this is the engineering video from the plane, just as CASSIOPE was, and that they simply mis-timed some camera motion, not some conspiracy to "hide" the end of the video. I mean...we've seen what the reception did to the video from CRS-3, and the ice on OrbComm. Even people who can bring a rocket down from orbit are occasionally limited by the systems they have set up to document it.The future path of this entire company depends on the results of this breakthrough testing - testing that costs a good bit of money. Do you really believe that SpaceX is depending on only one hand-held camera to capture the results?
- Ed Kyle
Well, the good news is that we're likely to see a barge landing in less than 2 months. Imagine the video from an observation boat moored nearby, or even from land if the barge is just offshore. THAT will be impressive.
The future path of this entire company depends on the results of this breakthrough testing - testing that costs a good bit of money. Do you really believe that SpaceX is depending on only one hand-held camera to capture the results?
Do you really believe that SpaceX is depending on only one hand-held camera to capture the results?
If so, you are willing to believe that this company is just a bunch of amateurs. I am certain that it is not.Do you really believe that SpaceX is depending on only one hand-held camera to capture the results?As a matter of fact, yes, I *can* believe that.
If so, you are willing to believe that this company is just a bunch of amateurs. I am certain that it is not.
Engineering video during launch vehicle R&D is standard stuff. Engineers put recoverable film video cameras on board Redstone and Atlas and Thor and Titan and Saturn, etc., during the 1950s and 60s to capture key information, even with masses of telemetry available.
Maybe you want to believe that SpaceX has experienced nothing but perfection, that there is no detailed record of the "interesting" hiccups.
SpaceX has recorded those moments, including, I believe, the sudden dis-assembly of the Orbcomm first stage after its successful landing. The company has not shown those moments in their finest detail to the public. That is fine, but lets not pretend that the records do not exist or that the hiccups never happened.
We're getting firmly into tin-foil hat land here.
Heh, is that a picture of your good self + cat?
The external sploosh starts earlier than the internal sploosh, but I wonder if that might be steam that's not visible to the internal camera, rather than the actual sploosh.
Epic!
Is the Orbcomm external and internal lined up?
The "MVac ignition" call comes what seems like a beat or two too much later than the ignition of the MVac.
There's websites that you can use to generate music - maybe ujam.com?Youtube has some free stuff too. I think it'd be worth adding if I remove the second song, otherwise it's quite a short duration of 'silence' anyway. Youtube also has a beta system to try to extract the music without affecting the rest of the audio... so I could keep the engine sounds and change the song if it works.
I'm thinking the last few seconds of the external video are actually slowed down from realtime. SpaceX has widely used 60 fps cameras for launch (http://www.bandpro.com/blog/falcon9-launch/) and Grasshopper-related videos. If the footage is being played back at 30 fps it would make sense for it to appears to last 2x as long.
Hmm.
The resolution and quality is bad, but there appears to be another vapour/donut that starts later. Basically the mist disc is quite thin, then a second thicker disc starts. Very subtle.
(btw: Youtube can remove audio very well! Any suggestions for music welcome :) )
The spec specifically states the valve is used on the vacuum Merlin. Any idea why they would use a different valve on the second stage?
That's essentially what you do with face throttling. You have to avoid pump stall, but that just means throttling the GG, which is how the Merlin apparently does it.
http://jasc-controls.com/jasc-industry-listing/space/space-fluid-management/bi-propellant-valve/
The spec specifically states the valve is used on the vacuum Merlin. Any idea why they would use a different valve on the second stage?
That's essentially what you do with face throttling. You have to avoid pump stall, but that just means throttling the GG, which is how the Merlin apparently does it.
http://jasc-controls.com/jasc-industry-listing/space/space-fluid-management/bi-propellant-valve/
Hmm.
The resolution and quality is bad, but there appears to be another vapour/donut that starts later. Basically the mist disc is quite thin, then a second thicker disc starts. Very subtle.
If I line that up with the side camera it is almost perfect....
To the viewer... I don't think they'll pick a difference though.
(btw: Youtube can remove audio very well! Any suggestions for music welcome :)
Hmm.
The resolution and quality is bad, but there appears to be another vapour/donut that starts later. Basically the mist disc is quite thin, then a second thicker disc starts. Very subtle.
If I line that up with the side camera it is almost perfect....
time alt speed range note
km mps km
+1:00 13 450 2.5
+2:20 54 1400 21
+2:25 40 sep
+9:23 ? ? ? retro burn
+11:12 ? ? ? landing burn
+11:43 ? 0 330 kaboom
Orbcomm was significantly lighter than AsiaSat6.More likely had to do with vertical velocity at MECO. If you take a steeper initial trajectory, you have more time before the reentry burn.
I have nothing to do with rockets but I would guess the first stage needed some throttling down and therefore a longer flight of the first stage. It would explain the difference. Or am I wrong with it?