Author Topic: LIVE: Space Falcon 9 Flight 2 Static Fire - December 4, 2010 (Read 174551 times)

yg1968 · « **Reply #200 on:** 12/03/2010 07:02 pm »

Will there be another attempt tomorrow?

Chris Bergin · « **Reply #201 on:** 12/03/2010 07:02 pm »

24 hour scrub recycle.

iamlucky13 · « **Reply #202 on:** 12/03/2010 07:08 pm »

Quote from: Jim on 12/03/2010 06:46 pm

The other logo has a P-POD on it.

I haven't found an image online that exactly matches matches that logo, but I think you're right:

butters · « **Reply #203 on:** 12/03/2010 07:21 pm »

Anything on why the static fire attempt was delayed for several hours this morning?

Did they simply decide to sleep in, or were they having problems that prevented them from beginning the tanking process?

MP99 · « **Reply #204 on:** 12/03/2010 07:37 pm »

Quote from: Chris Bergin on 12/03/2010 05:57 pm

Now have cross confirmation this static fire didn't go to plan.

Aborted due to high chamber pressure on one engine (around 1.5 seconds). Trying to recycling for another attempt today. 3pm is the range limit.

Sounds like the static fire has earned it's keep - although this would presumably have been detected before release if this was a real launch.

Do we know how many times an array of nine Merlins has been fired up before? I presume most times would have been on the test stand?

If this turned out to be a major issue for engine #6, could it be replaced?

cheers, Martin

vt_hokie · « **Reply #205 on:** 12/03/2010 08:25 pm »

Potential 24 hour turnaround is good news at least!

butters · « **Reply #206 on:** 12/03/2010 09:12 pm »

This has happened before, several times actually.

The first launch attempt of F9 Flight 1 was aborted on engine stage because of a high chamber pressure reading, and they were able to recycle and launch successfully in the same window. It also happened with at least one of the F1 vehicles.

They haven't yet nailed down the appropriate chamber pressure threshold in the launch commit criteria. Either that or they haven't yet refined the Merlin start sequence as well as they need to in order to achieve consistent engine start transients.

It's not a major problem. Their abort and recycle capabilities are really world-class. But they do exercise these capabilities more often than desirable. I think they'll tune this out in the next couple of launches.

Chris Bergin · « **Reply #207 on:** 12/03/2010 09:15 pm »

SpaceX PAO have just sent out:

"UPDATE: Today the 1st static fire attempt aborted at T-1.1 seconds due to high engine chamber pressure. We are reviewing data now and will make a second attempt tomorrow. Thanks for watching!"

iamlucky13 · « **Reply #208 on:** 12/03/2010 09:20 pm »

Quote from: MP99 on 12/03/2010 07:37 pm

Quote from: Chris Bergin on 12/03/2010 05:57 pm
Now have cross confirmation this static fire didn't go to plan.

Aborted due to high chamber pressure on one engine (around 1.5 seconds). Trying to recycling for another attempt today. 3pm is the range limit.

Sounds like the static fire has earned it's keep - although this would presumably have been detected before release if this was a real launch.

Do we know how many times an array of nine Merlins has been fired up before? I presume most times would have been on the test stand?

If this turned out to be a major issue for engine #6, could it be replaced?

cheers, Martin

Was that 1.5 seconds after ignition or 1.5 seconds after reaching full thrust? If the latter, I think it would have released, although I don't know the exact startup timing.

Which does not give us any information at this point if it would have been a real problem in flight. The shutdown criteria should be conservative, and it may have been brief spike that could settle out.

As far as firing a full cluster of Merlins, quite a few times. I forget if there was one or two static fires on the pad for flight 1, plus several firings on the test stand prior to shipping to the Cape, including at least one full-duration firing. I'm feeling too lazy to bother going back and counting, and I don't think they've reported all of the Texas firings.

It's a good bet they can't replace the engine on the pad because of the limited room for lifting equipment, and I somewhat doubt they have a spare on hand in Florida. I presume they can do a replacement in the hangar without removing the entire thrust structure, but I don't recall them having done it before.

EDIT - Chris just posted T-1.1 cutoff time above, so the rocket wouldn't have released.

e of pi · « **Reply #209 on:** 12/03/2010 10:53 pm »

Would this have been a "go" condition on flight day? If this had come through, would it have just shut that engine down and gone for it on the other 8? They've talked about engine-out as being a big safety thing in Falcon 9, but do they have the software set up to trust in that?

ugordan · « **Reply #210 on:** 12/03/2010 10:57 pm »

Quote from: e of pi on 12/03/2010 10:53 pm

Would this have been a "go" condition on flight day?

Read what other people are saying. This happened before T-0. No launch commit would have occured.

Kabloona · « **Reply #211 on:** 12/04/2010 12:33 am »

Quote from: e of pi on 12/03/2010 10:53 pm

Would this have been a "go" condition on flight day? If this had come through, would it have just shut that engine down and gone for it on the other 8? They've talked about engine-out as being a big safety thing in Falcon 9, but do they have the software set up to trust in that?

No, all 9 engines must be running within parameters for them to launch. Engine out capability is a margin/safety nice-to-have, but you don't launch with an engine out. You abort, fix the problem (if it's real) and try again. Someone else may have better info, but it looks like the aborts they've had are due to tight software limits on chamber pressure being exceeded by engine start transients, and not a "real" hardware problem, at least not that I've heard. It's a learning curve and they're on the steep part of it.

Lee Jay · « **Reply #212 on:** 12/04/2010 12:58 am »

Quote from: Kabloona on 12/04/2010 12:33 am

Someone else may have better info, but it looks like the aborts they've had are due to tight software limits on chamber pressure being exceeded by engine start transients, and not a "real" hardware problem, at least not that I've heard. It's a learning curve and they're on the steep part of it.

I've spent a good deal of time dealing with the issue of signal-to-noise ratio in fault detection. It's not an easy thing to do to detect real faults quickly while rejecting nuisance faults at the same time. I've come up with one lesson learned on this - windows of acceptable parameters are not very reliable, even with filtering. I've switched to model-based fault detection and the difference in performance is absolutely unbelievable.

joshcryer · « **Reply #213 on:** 12/04/2010 01:01 am »

Quote from: Kabloona on 12/04/2010 12:33 am

Someone else may have better info, but it looks like the aborts they've had are due to tight software limits on chamber pressure being exceeded by engine start transients, and not a "real" hardware problem, at least not that I've heard. It's a learning curve and they're on the steep part of it.

Data is good. I learned a lot about how they do it on F9 flight 1. Apparently they do indeed set the margins extremely low, basically completely insane expectations for the rocket. I actually like that they do it this way. I like it a lot. When you have a several hour turn around time restart capability, use it. At least until you have a whole lot of data to go by and can decide just how it's going to behave.

Chris Bergin · « **Reply #214 on:** 12/04/2010 02:53 am »

Just so people know, we'll continue on this thread for the second attempt.

Kabloona · « **Reply #215 on:** 12/04/2010 02:58 am »

Quote from: joshcryer on 12/04/2010 01:01 am

Quote from: Kabloona on 12/04/2010 12:33 am
Someone else may have better info, but it looks like the aborts they've had are due to tight software limits on chamber pressure being exceeded by engine start transients, and not a "real" hardware problem, at least not that I've heard. It's a learning curve and they're on the steep part of it.

Data is good. I learned a lot about how they do it on F9 flight 1. Apparently they do indeed set the margins extremely low, basically completely insane expectations for the rocket. I actually like that they do it this way. I like it a lot. When you have a several hour turn around time restart capability, use it. At least until you have a whole lot of data to go by and can decide just how it's going to behave.

It does make good sense to start out super-conservative on the LCC and gradually relax or adjust some of the constraints as they get more experience with the vehicle. Plus it gives them plenty of practice with the abort/recycle. Pretty soon the launch team will have that procedure memorized, if they don't already.

Halidon · « **Reply #216 on:** 12/04/2010 05:16 am »

Assuming this is the same schedule as the prior attempt, right?

ugordan · « **Reply #217 on:** 12/04/2010 09:42 am »

Yes, appears they again have the 9 AM - 3 PM EST Range window to work with.

Chris Bergin · « **Reply #218 on:** 12/04/2010 11:13 am »

Nothing from SpaceX since they finally got around to confirming the problem (over fours hours after the abort). Let's hope we've got some sources who are at work on a Saturday.

joshcryer · « **Reply #219 on:** 12/04/2010 11:56 am »

"SpaceX Attempting static fire again today. Window is 9 AM to 3 PM EST, 6 AM to 12 PM Pacific. Thanks for your patience with the webcast yesterday, we'll be trying it again today, will update when its live."

Via facebook.

edit, source: http://www.facebook.com/SpaceX