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

[Robotbeat]

It looked like there was more unburnt propellant before it actually was shut down.

When Elon asserts F9 shut down the engine, I interpret him to mean it shut down flow of propellant to the engine. Is it fair to assume they do that fuel-rich, i.e. cut the oxidizer flow first?

I'd call it hardware-rich combustion.

[Kabloona]

Official confirmation from Elon is that an anomaly occurred in an engine and it was shut down prematurely by the onboard computer.  Nothing about an explosion in that official statement.

And the word "explosion" is never going to come from Elon or SpaceX in describing what happened, no matter what happened, so don't hold your breath. It'll be called a turbopump failure, or words to that effect.

[Kabloona]

Zephyrus just posted a link to a slo-mo YouTube video of the event, and it clearly shows an engine plume brightening and changing shape BEFORE the chunks start to fly. In that slo-mo, it looks very much like an engine exploding and blowing out chunks of corner fairing, etc.

Still consistent with a fairing failure.  If the fairing hits the nozzle, the effect on the plume propagates backwards at several km/sec, whereas the fairing itself is only accelerating from "rest" due to the force of the flow and the acceleration of the rocket, so is not anywhere near as fast.

So you'll see the plume deform before you see the fairing cross in front of the engine.

But if you look at the trajectory of the pieces being ejected, they're being blown OUTWard, not just backward by the slipstream, and in multiple pieces that sure suggest an RUD.

[zeaman]

Did anyone notice the ice falling from the walls of Lox tanks, approximately at T-5:00 (on NasaTV live).   It happened on all previous missions, but today it was heavier (air humidity?). The falling pieces might hit the engine fairings...

[meekGee]

Zephyrus just posted a link to a slo-mo YouTube video of the event, and it clearly shows an engine plume brightening and changing shape BEFORE the chunks start to fly. In that slo-mo, it looks very much like an engine exploding and blowing out chunks of corner fairing, etc.

Still consistent with a fairing failure.  If the fairing hits the nozzle, the effect on the plume propagates backwards at several km/sec, whereas the fairing itself is only accelerating from "rest" due to the force of the flow and the acceleration of the rocket, so is not anywhere near as fast.

So you'll see the plume deform before you see the fairing cross in front of the engine.

But if you look at the trajectory of the pieces being ejected, they're being blown OUTWard, not just backward by the slipstream, and in multiple pieces that sure suggest an RUD.

Yup - this one I'm still scratching my head over... 

See, while the turbo pump is spinning very fast, the rotor is not that heavy.  The pieces will have lost a lot of energy busting through the case and whatever ballistic protection they have there, so I can't see the shrapnel transferring enough momentum to the fairing (which is thin) and causing pieces to go THAT far out. 

And the pieces that appear to be flying outwards are very large too.

Could it be that they only appear to fly out due to camera angle?

But, you maybe be right.  If the pump shreds both propellant lines, you could get a mixture inside the cavity enclosed by the fairing, and if that ignites, it would indeed transfer well onto the fairing and knock it out.

In that case, btw, there would be some serious sideways impulse to the side of the rocket - above and beyond the aerodynamic imbalance that's just getting created, and obviously the thrust imbalance.

Wow. 

Can we see the nozzles compensating?

[cordor]

I have made a slow motion video of the anomaly. Please tell me if I this is not fair use and I will remove it immediately.


Of course we will have to wait for an official assessment but I would say that something has definitely happened and it is not just some clouds.


Sorry for the slowed down audio, I could not find the exact mencoder option to kill it.

(P.S. Moved from the other thread due to moderator indications).

looks to me was just ice falling off the rocket while passing max-q.

[Jason1701]

I have made a slow motion video of the anomaly. Please tell me if I this is not fair use and I will remove it immediately.


Of course we will have to wait for an official assessment but I would say that something has definitely happened and it is not just some clouds.


Sorry for the slowed down audio, I could not find the exact mencoder option to kill it.

(P.S. Moved from the other thread due to moderator indications).

looks to me was just ice falling off the rocket while passing max-q.

Elon said it was an engine problem.

[spectre9]

I'm going with a nozzle failure.

Lots of exposed tubes on a Merlin 1C. How humid has it been at the pad?

I worry about rocket engines rusting away. I don't like to see launch vehicles rolled around outdoors too often. Just put them on the pad and fire them off, don't expose them to the elements.

[M_Puckett]

looks to me was just ice falling off the rocket while passing max-q.

Did you bother to watch the slo-mo video?

That was certainly NOT just ice falling off!

[meekGee]

I have made a slow motion video of the anomaly.

... which clearly indicates the anomaly was caused by a ghoul - you can hear it clearly at 1:16, and if you play it backwards it says: "Engine one is toast".

[Kabloona]

I have made a slow motion video of the anomaly.

... which clearly indicates the anomaly was caused by a ghoul - you can hear it clearly at 1:16, and if you play it backwards it says: "Engine one is toast".

LOL...as I was watching NASA TV, at one point one of the console guys jumped out of his chair like something on his screen just went very bad...but there was no other indication of an anomaly, so I shrugged it off...now I'm wondering if that was the propulsion guy seeing Engine 1 shutdown on his screen...

[meekGee]

Kabloona - I'm going to partially back away from my first "single cause" argument.

It only holds if the engine ballistic protection is placed all around the engine (as might be the case if it's part of the engine itself).

If it's only between engines (as would be the case if it's part of the 3x3 thrust structure) then the turbine failure could knock out the fairing without requiring a second failure, and so this is equally likely.

[Kabloona]

Kabloona - I'm going to partially back away from my first "single cause" argument.

It only holds if the engine ballistic protection is placed all around the engine (as might be the case if it's part of the engine itself).

If it's only between engines (as would be the case if it's part of the 3x3 thrust structure) then the turbine failure could knock out the fairing without requiring a second failure, and so this is equally likely.

Eh, either way, I think we're agreeing that the engine most likely RUD'd.

[Hooperball]

Simply amazing that this (explosion) didn't turn into a a loss of mission.  They'll probably call it a success because it "proves" the robustness of their design.

I call it by the skin of their teeth!

S

[meekGee]

at one point one of the console guys jumped out of his chair like something on his screen just went very bad...but there was no other indication of an anomaly, so I shrugged it off...now I'm wondering if that was the propulsion guy seeing Engine 1 shutdown on his screen...

I was wondering if there was any footage like that. 

Also, they had the com loops configured so that none of the important contingency chatter made it to the public airwaves. (But of course the ijit with the "small fires on the deck" made it through anyway.)

[Kabloona]

at one point one of the console guys jumped out of his chair like something on his screen just went very bad...but there was no other indication of an anomaly, so I shrugged it off...now I'm wondering if that was the propulsion guy seeing Engine 1 shutdown on his screen...

I was wondering if there was any footage like that. 

Also, they had the com loops configured so that none of the important contingency chatter made it to the public airwaves. (But of course the ijit with the "small fires on the deck" made it through anyway.)

Yeah, he jumped like he'd been poked with an electric cattle prod, but fortunately for him, the words that came out of his mouth were shielded from public scrutiny 

[rdale]

Simply amazing that this (explosion) didn't turn into a a loss of mission.  They'll probably call it a success because it "proves" the robustness of their design.

I call it by the skin of their teeth!

No evidence of explosion yet, and no reason to think that this was one hair from LOM.

This thread is a great example of why companies don't bother releasing info in the first place. Too many Internet experts.

[Chris-A]

Since the rocket cam feed was delayed, the failure can be seen with the dual camera view

[Hooperball]

Simply amazing that this (explosion) didn't turn into a a loss of mission.  They'll probably call it a success because it "proves" the robustness of their design.

I call it by the skin of their teeth!

No evidence of explosion yet, and no reason to think that this was one hair from LOM.


What do you call all that debris flying sideways away from the rocket?

S

[brtbrt]

Thanks for posting the slo-mo video, Zephyrus.

I looked at the few frames just before the event, and I think I'm seeing significant combustion instability 3-4 frames ahead. That is consistent with both propellant flow changes (think a problem in the turbopump) but also with exterior flow disruptions (ice shearing off the fairing, or just plain MaxQ). And it's also possible that the combustion instability was caused by small variations in the manufacturing of the combustion chamber.

In either case, I think the combustion instability caused structural failure of the nozzle, followed by the fairing separation. I think the large triangular object in the exhaust stream is the fairing, not the engine nozzle.

I believe that the turbopumps continued to spin for some time thereafter, because I don't think the volume of propellants dumped into the exhaust could have come out without them - tank pressurization shouldn't have delivered that volume all by itself. So I don't think the TP let go.

If I'm right, the impact on schedule might be significant, as inherent combustion instability problems take time to solve.