SpaceX Falcon 9/Dragon CRS SpX-1 MISSION GENERAL DISCUSSION

[Garrett]

A SpaceX update page from 2005 mentions that during Merlin development the company had witnessed a number of RUD events. (Rapid Unscheduled Disassembly). The update specifically mentions a chamber rupture, so, it seems likely that SpaceX has witnessed a similar event before during Merlin testing.

So if the engine issue on SpX-1 was a chamber rupture event, is this old 2005 update a form of evidence that SpaceX engineers were probably not wholly surprised to see such an issue occur and had engineered F9 accordingly?
Not knowing anything about the history of chamber rupture events on other rocket engines, I have no idea how this fits into the general context of rocket engineering.

What is the main cause of chamber rupturing? Lack of engineering experience/knowledge/heritage? Or is it simply a question of rocket engineering tech having very little margin when it comes to the task of overcoming the physics of confined explosions?

[krytek]

A SpaceX update page from 2005 mentions that during Merlin development the company had witnessed a number of RUD events. (Rapid Unscheduled Disassembly). The update specifically mentions a chamber rupture, so, it seems likely that SpaceX has witnessed a similar event before during Merlin testing.

So if the engine issue on SpX-1 was a chamber rupture event, is this old 2005 update a form of evidence that SpaceX engineers were probably not wholly surprised to see such an issue occur and had engineered F9 accordingly?
Not knowing anything about the history of chamber rupture events on other rocket engines, I have no idea how this fits into the general context of rocket engineering.

What is the main cause of chamber rupturing? Lack of engineering experience/knowledge/heritage? Or is it simply a question of rocket engineering tech having very little margin when it comes to the task of overcoming the physics of confined explosions?

2005 is not even the same engine && system.

[Chris Bergin]

Used some of those photos (I think we're over 300, at 3Mb or so each!) in the article I've just put on:

Dragon enjoying ISS stay, despite minor issues – Falcon 9 investigation begins:

http://www.nasaspaceflight.com/2012/10/dragon-iss-stay-minor-issues-falcon-9-investigation/

I so like calm and informative articles. Beauty, Chris.

Thanks Robert, appreciate that!

[woods170]

2005 is not even the same engine && system.

Read the update again. It clearly states that the measures to safeguard against a chamber rupture are being taken on Falcon 9.

Then there is the question of dealing with the comparatively rare case of a chamber rupture. To protect against this, Falcon 9 will have a blast shield protecting the entire base of the vehicle just above the gimbal joints of the engines. In addition, there will be fireproofed Kevlar fragment containment around each engine, similar to those present in jet engine nacelles.

Note: emphasis mine.

Additional note: in 2005, when development of Falcon 5 shifted to development of Falcon 9, it was still assumed that Merlin-1B would power Falcon 9. Merlin 1B was a version of Merlin 1A, with increased thrust. Previous chamber ruptures had been witnessed on Merlin 1A. So, the decision to 'armor'  Falcon 9 against such an event was taken with the Merlin 1A/Merlin 1B legacy in mind. It was not until 2006 that SpaceX took the decision to switch Falcon 9 to the newly being developed Merlin 1C.
I don't know if SpaceX ever witnessed the kind of failure on Merlin 1C, during test-firing, observed on the CRS-1 launch. But it was probably a good thing that Falcon 9 retained the 'armor' that was designed-in based on their experience with Merlin 1A and Merlin 1B.

[baldusi]

If I'm not mistaken, those failures where seen on the ablatively cooled chambered Merlin. A complete different chamber with completely different failure modes. Since they where using a pintle injector, they actually concentrated the most extreme temperatures in a ring. That was too much to take for the ablative material. Thus, they switched to regen. In the end ablative chamber is sort of incompatible with pintle injectors.
And this failure was on a fuel dome, which sits atop the injector. And it was a rupture, not an explosion. Look for failed pressure vessels to see the difference. In an explosion nothing is left. A rupture looks more like if someone from the inside had shoot a bullet. If it had been an explosion they wouldn't had have kept receiving telemetry from the engine.

[Rocket Science]

Not to repeat myself but the salvaging of engines on the last flight should be looked at as part of the cost of doing business and would do much in putting the cause of failure to rest. Providing of course that they can locate them and not too inaccessible…

[woods170]

Not to repeat myself but the salvaging of engines on the last flight should be looked at as part of the cost of doing business and would do much in putting the cause of failure to rest. Providing of course that they can locate them and not too inaccessible…

Generally speaking ocean salvage, let alone DEEP ocean salvage, is a very expensive business. Has anyone ever tried to salvage rocket engines from the ocean floor, just to aid in the failure analysis, other than Challenger?

[Rocket Science]

Not to repeat myself but the salvaging of engines on the last flight should be looked at as part of the cost of doing business and would do much in putting the cause of failure to rest. Providing of course that they can locate them and not too inaccessible…

Generally speaking ocean salvage, let alone DEEP ocean salvage, is a very expensive business. Has anyone ever tried to salvage rocket engines from the ocean floor, just to aid in the failure analysis, other than Challenger?

Yes, I totally agree with you, it is not cheap. This is one of those cost/benefit questions. They had reason to recover the remains of the recent Air France crash, so I view this as similar investigation. One had to judge the engineering value and also the potential relations with the prospective customer and their future confidence in the product.

I use the airliner as an example because Elon uses it when speaking of reusability of his Falcon rockets and wishing to get it down to airliner like operations. So why not treat it like an air crash recovery…

Edit:to add..

[Jim]

Not to repeat myself but the salvaging of engines on the last flight should be looked at as part of the cost of doing business and would do much in putting the cause of failure to rest. Providing of course that they can locate them and not too inaccessible…

Generally speaking ocean salvage, let alone DEEP ocean salvage, is a very expensive business. Has anyone ever tried to salvage rocket engines from the ocean floor, just to aid in the failure analysis, other than Challenger?

Yes, I totally agree with you, it is not cheap. This is one of those cost/benefit questions. They had reason to recover the remains of the recent Air France crash, so I view this as similar investigation. One had to judge the engineering value and also the potential relations with the prospective customer and their future confidence in the product.

I use the airliner as an example because Elon uses it when speaking of reusability of his Falcon rockets and wishing to get it down to airliner like operations. So why not treat it like an air crash recovery…

Edit:to add..

Because it not like an airline crash.  There are big differences in velocity and break effects, not to mention that airliners don't experience reentry heating nor are they subject to severe environments experienced in a nominal staging

[Rocket Science]

Not to repeat myself but the salvaging of engines on the last flight should be looked at as part of the cost of doing business and would do much in putting the cause of failure to rest. Providing of course that they can locate them and not too inaccessible…

Generally speaking ocean salvage, let alone DEEP ocean salvage, is a very expensive business. Has anyone ever tried to salvage rocket engines from the ocean floor, just to aid in the failure analysis, other than Challenger?

Yes, I totally agree with you, it is not cheap. This is one of those cost/benefit questions. They had reason to recover the remains of the recent Air France crash, so I view this as similar investigation. One had to judge the engineering value and also the potential relations with the prospective customer and their future confidence in the product.

I use the airliner as an example because Elon uses it when speaking of reusability of his Falcon rockets and wishing to get it down to airliner like operations. So why not treat it like an air crash recovery…

Edit:to add..

Because it not like an airline crash.  There are big differences in velocity and break effects, not to mention that airliners don't experience reentry heating nor are they subject to severe environments experienced in a nominal staging

I agree with you Jim with the forces involved. I also don’t see airliner like ops in the near future at this point, but apparently he does… Do you feel that there would be nothing to learn or see if recoverable?

[Prober]

Not to repeat myself but the salvaging of engines on the last flight should be looked at as part of the cost of doing business and would do much in putting the cause of failure to rest. Providing of course that they can locate them and not too inaccessible…

Generally speaking ocean salvage, let alone DEEP ocean salvage, is a very expensive business. Has anyone ever tried to salvage rocket engines from the ocean floor, just to aid in the failure analysis, other than Challenger?

Yes, I totally agree with you, it is not cheap. This is one of those cost/benefit questions. They had reason to recover the remains of the recent Air France crash, so I view this as similar investigation. One had to judge the engineering value and also the potential relations with the prospective customer and their future confidence in the product.

I use the airliner as an example because Elon uses it when speaking of reusability of his Falcon rockets and wishing to get it down to airliner like operations. So why not treat it like an air crash recovery…

Edit:to add..

Because it not like an airline crash.  There are big differences in velocity and break effects, not to mention that airliners don't experience reentry heating nor are they subject to severe environments experienced in a nominal staging

I agree with you Jim with the forces involved. I also don’t see airliner like ops in the near future at this point, but apparently he does… Do you feel that there would be nothing to learn or see if recoverable?

too late now......the ship(s) should have put to sea launch day and try and recover any debris.   

[john smith 19]

Do you have any *specific* examples where their indicated payload/orbit parameters are pushing the limits of the vehicles capabilities? If you don't then is there *any* reason to expect the results of such a mission to be any worse than the ones today?

Most GTO/GSO and all planetary missions

Firstly my apologies for not getting back to you sooner.

I would have expected *all* launchers to be operating at the limits of their performance envelopes for these missions. As Spacex has not *flown* any of these missions on an F9 are you saying you don't think  [edit] they have enough margin to carry *any* secondary payloads or that the size of secondary they could carry is overly optimistic if anything goes wrong with the primary trajectory?

[Jim]

you don't think  have enough margin

Missing some words.

But if it is "they", then no.  Comsats use any excess performance to reduce inclination, raise perigee or even increase apogee if it is a sub-synchronous orbit.  Planetaries will add more propellant or use the addition performance to increase prop margins.

[john smith 19]

you don't think  have enough margin

Missing some words.

But if it is "they", then no.  Comsats use any excess performance to reduce inclination, raise perigee or even increase apogee if it is a sub-synchronous orbit.  Planetaries will add more propellant or use the addition performance to increase prop margins.

Aren't those choices (permitting secondaries, use of additional capacity) the same ones that *all* LV's in this class have? AFAIK Ariane, Delta IV and Atlas V all offer secondary payloads.
I'm not sure on the Russian position (It's a subject I'm peripherally aware of rather than one I've looked into).

[Jim]

Aren't those choices (permitting secondaries, use of additional capacity) the same ones that *all* LV's in this class have? AFAIK Ariane, Delta IV and Atlas V all offer secondary payloads.

No.  See the GPS that just launched.  The spacecraft had no use for the excess performance. Same goes for DSMP and some other launches.

It has nothing to with launch vehicle class because the actual performance of each vehicle is different, it has to with the payload assigned to the vehicle.  The same payload might have excess margin on one vehicle and no margin on another.

[nlec]

http://news.discovery.com/space/spacex-cargo-return-dragon-station-121026.html

Dragon is due to be released from the station's robot arm at 9:26 a.m. EDT on Sunday and splash down in the Pacific Ocean off the coast of Baja California at 3:20 p.m. that same day. Its cargo includes 866 pounds of science gear and experiment samples -- and 400 bags of crew urine.

Emphasis added.

[manboy]

http://news.discovery.com/space/spacex-cargo-return-dragon-station-121026.html

Dragon is due to be released from the station's robot arm at 9:26 a.m. EDT on Sunday and splash down in the Pacific Ocean off the coast of Baja California at 3:20 p.m. that same day. Its cargo includes 866 pounds of science gear and experiment samples -- and 400 bags of crew urine.

Emphasis added.

Those bags of urine are most likely experiment samples. Kidney stones and calcium loss by urination is both a common and serious problem for long duration spaceflights.

[john smith 19]

No.  See the GPS that just launched.  The spacecraft had no use for the excess performance. Same goes for DSMP and some other launches.

It has nothing to with launch vehicle class because the actual performance of each vehicle is different, it has to with the payload assigned to the vehicle.  The same payload might have excess margin on one vehicle and no margin on another.

I wouldn't doubt it otherwise people would not shift LV's as their payloads exceeded it's absolute capabilities.

You were talking of specific missions. AFAIK GPS are *well* under the those limits (altitude 800km+? in Earth orbit rather than escape). DSMP seems to be a catch all for various military capabilities. I could imagine *some* are pretty near the limits of the currently manifested LV's, while others are not.

You seemed to have a *specific* reason to mistrust Spacex's policy on secondary payloads and I'm suggesting that it's *not* that much different than that of other LV's. If I'm wrong please explain my misunderstanding of your position.

CRS1 would seem to be an *exceptionally* unlucky set of circumstances for Orbcomm of an under performing 1st stage *multiplied* by NASA constraints that prevented a fall back plan that had a 1 in 20 chance of failure. I think if the consequence of a failure had been *anything* other than an ISS collision (or should that be strictly *potential* collision) and any other primary but NASA Spacex there would not have been a gate on their software and Spacex would have tried the burn.

I'll note that by The Aerospace Corps 3/7 rule (up to 3rd launch a failure is likely to be design, 4-7 is likely to be mfg) this is still *probably* a design flaw to be designed out. I think it would be instructive to compare the *consequence* of the event on F9 if the *same* event had happened on any of the other LV's (crewed or cargo) that may fly to the ISS. I think in *all* cases it would be a LOC/LOM case, not because any of them are bad designs but they essentially *rely* on perfection and F9 (on the 1st stage at least) does not.

[Lee Jay]

Late tonight, station astronauts will depressurize the spacecraft.

Okay, I'm curious.  Why is this done?  Isn't the pressurization good for the cargo and for the spacecraft's integrity during and after reentry?

[hrissan]

Late tonight, station astronauts will depressurize the spacecraft.

Okay, I'm curious.  Why is this done?  Isn't the pressurization good for the cargo and for the spacecraft's integrity during and after reentry?

The word "vestibule" was likely omitted accidentally?