Author Topic: LIVE: SpaceX - Falcon I (Mk.II) NET March 20 (Attempt 2) (Read 265149 times)

yinzer · « **Reply #420 on:** 03/21/2007 02:15 am »

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aero313 - 20/3/2007 8:09 PM

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Stargazin2nite - 20/3/2007 10:12 PM

Danderman -- good point -- I just checked the payload in more detail and it does look like instrumentation to characterize the launch. At first I was under the impression that DARPA was adding an additional functional satellite, but that appears not to be the case.

In any event, I am still amazed that a company with only 250 people have accomplished this!

Orbital had abour 150 people when Pegasus had a successful maiden flight. As with SpaceX, some of those were working other programs at the time.

Orbital did good work. SpaceX is trying to go both cheaper and bigger than Orbital did, and they don't have a very experienced subcontractor like Orbital did in Hercules (?), but they all still have the problem that there are no payloads.

aero313 · « **Reply #421 on:** 03/21/2007 02:22 am »

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Norm Hartnett - 20/3/2007 10:20 PM
Secondly I am appalled at the virulent nature of some of the comments I’ve seen here. What is the affiliation of these people, NASA, LockMart, USA? Whatever it is I have rarely seen such sour grapes. If any of you could do half as well with twice the budget we would be a lot further into the VSE.

Not to denigrate what SpaceX has done, but why do people seem to forget that the Pegasus vehicle was developed for $50M (about $80M in today's dollars) of total private investment - including the development of three brand new solid rocket motors - by fewer people and in only 30 months from program start to completely successful maiden flight?

rumble · « **Reply #422 on:** 03/21/2007 02:22 am »

Watch the video at high speed (windows media player 11 allows up to 16x playback speed).

The recontact after stage sep: It looks almost as if the 2nd stage had a forced pitch... almost as if 3 of 4 ullage thrusters fired (not sure if falcon has these). The second stage turned and bumped the 1st stage with the engine bell. After the contact, the 2nd stage started again to accelerate in the same direction. Had the kestrel not started when it did, the 2nd stage may have started an end-over-end roll.

The oscillation seems to start MUCH earlier than 4:30, but at a far smaller magnitude. A few times, it almost stops, but it comes back. It almost looks as if the gimbal is over-correcting problems that come up, and eventually, the gimbal (maybe aggravated by propellant slosh) got out of control. At the end of the video clip, a very obvious pitch and roll starts to happen.

Both of these could be tiny root problems that ended up in a less than perfect flight.

BUT, I was sitting on the edge of my chair the whole time, and I'll be ready for the next falcon flight! I expect the next launch will be even better.

NICE JOB SPACEX!! Impressive, to say the least!

marsavian · « **Reply #423 on:** 03/21/2007 02:25 am »

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jimvela - 20/3/2007 10:02 PM

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marsavian - 20/3/2007 8:46 PM
a bold quote
'He doesn't foresee needing another test flight before launching the first operational mission in late summer carrying the U.S. military's TacSat 1 spacecraft.'
http://www.space.com/missionlaunches/sfn_070320_spacex_falc1cntdwn.html
Well at least he's consistently in character. You have to be a bit arrogant to lead a bunch of scientists, engineers, techs, and associated riffraff :-). He's also demonstrated that he can and does learn. Oh, to be a fly on the wall tomorrow back in El Segundo...

Next up is more learning curve: Bring on the various government inspectors associated with launching a US asset.
DCMA, anyone?

He's too cavalier and I doubt anyone will agree to having their satellite go up until he has demonstrated a mission success as there are too many question marks now about the second stage. It also once again calls into question the wisdom of throwing money upfront at not one but two unproven launch systems for COTS.

aero313 · « **Reply #424 on:** 03/21/2007 02:29 am »

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marsavian - 20/3/2007 8:46 PM

'He doesn't foresee needing another test flight before launching the first operational mission in late summer carrying the U.S. military's TacSat 1 spacecraft.'

I think the Air Force will make that call, not Elon...

Lee Jay · « **Reply #425 on:** 03/21/2007 02:30 am »

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rumble - 20/3/2007 9:22 PM
The recontact after stage sep: It looks almost as if the 2nd stage had a forced pitch... almost as if 3 of 4 ullage thrusters fired (not sure if falcon has these). The second stage turned and bumped the 1st stage with the engine bell. After the contact, the 2nd stage started again to accelerate in the same direction. Had the kestrel not started when it did, the 2nd stage may have started an end-over-end roll.

Yep...on the replay, I'm seeing that acceleration as well.

If this were a solid body, I'd say the oscillation was caused by a lack of sufficient gain scheduling (reduction) as the inertia was reduced. But sloshing is a whole other matter. I have no clue about that.

Anyway, very, very cool video from the vehicle.

vt_hokie · « **Reply #426 on:** 03/21/2007 02:31 am »

If anything, this seems to highlight the need for multiple vehicles and some tolerance for failures with a new, unproven design! How long would it have taken Kistler to build a second vehicle had the first one failed? (The K-1 was to be reusable, of course, and as I recall they were planning to build just one for flight tests.)

Chris Bergin · « **Reply #427 on:** 03/21/2007 02:51 am »

Post launch article, with Elon quotes:

http://www.nasaspaceflight.com/content/?cid=5052

Danderman · « **Reply #428 on:** 03/21/2007 02:55 am »

My friends in South America are somewhat concerned about the landing zone for the second stage!

braddock · « **Reply #429 on:** 03/21/2007 02:58 am »

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marsavian - 20/3/2007 11:25 PM
He's too cavalier and I doubt anyone will agree to having their satellite go up until he has demonstrated a mission success as there are too many question marks now about the second stage.

Let me just say that if you heard Elon's voice on the conference call just now, you could never mistake him for "cavalier". In fact, the first reporter asked in effect if he was as shaken as he sounded. He said quite humbly that he tended to dwell excessively on the negative, and needs people to remind him of the positive. He recalled with some feeling that it has been a very stressful few days for him.

rdale · « **Reply #430 on:** 03/21/2007 02:59 am »

If it didn't complete its orbit, wouldn't it be down by now?

Seattle Dave · « **Reply #431 on:** 03/21/2007 03:00 am »

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rdale - 20/3/2007 10:59 PM

If it didn't complete its orbit, wouldn't it be down by now?

Yes.

Danderman · « **Reply #432 on:** 03/21/2007 03:03 am »

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rdale - 20/3/2007 8:59 PM If it didn't complete its orbit, wouldn't it be down by now?

The concern is that it may have landed somewhere around the equator in South America, but exactly where is unknown.

ratman · « **Reply #433 on:** 03/21/2007 03:07 am »

I just wonder - why everyone (including Chris) is talking about problem with "roll control" ? The vehicle had no roll - it was circular pitch/yaw motion...

Chris Bergin · « **Reply #434 on:** 03/21/2007 03:09 am »

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ratman - 21/3/2007 4:07 AM

I just wonder - why everyone (including Chris) is talking about problem with "roll control" ? The vehicle had no roll - it was circular pitch/yaw motion...

One for an engineer, but Elon quote: "We did see a roll control issue later in the second stage."

ratman · « **Reply #435 on:** 03/21/2007 03:12 am »

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Chris Bergin - 20/3/2007 12:09 AM
One for an engineer, but Elon quote: "We did see a roll control issue later in the second stage."

Well - he's wrong

Nick L. · « **Reply #436 on:** 03/21/2007 03:15 am »

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ratman - 20/3/2007 12:07 AM

I just wonder - why everyone (including Chris) is talking about problem with "roll control" ? The vehicle had no roll - it was circular pitch/yaw motion...

I believe that in addition to the pitch/yaw precession, later on in the second stage operation you could see the stage was beginning to roll heavily just before the video cut. Perhaps the precession wouldn't have caused a problem, whereas the rolling would have.

NotGncDude · « **Reply #437 on:** 03/21/2007 03:16 am »

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vt_hokie - 20/3/2007 11:31 PM

If anything, this seems to highlight the need for multiple vehicles and some tolerance for failures with a new, unproven design! How long would it have taken Kistler to build a second vehicle had the first one failed? (The K-1 was to be reusable, of course, and as I recall they were planning to build just one for flight tests.)

The K-1's whole point is to be fully reusable. And that thing is a monster. I wouldn't expect more than one any time soon. SpaceX strategy of getting the foot on the door with the little one is looking pretty good.

Danderman · « **Reply #438 on:** 03/21/2007 03:18 am »

A really stupid question: is it possible that the loss of video was simply caused by the vehicle being too far downrange? And that the loss of video had nothing to do with the vehicle failure?

I am just asking.....

ratman · « **Reply #439 on:** 03/21/2007 03:24 am »

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I believe that in addition to the pitch/yaw precession, later on in the second stage operation you could see the stage was beginning to roll heavily just before the video cut. Perhaps the precession wouldn't have caused a problem, whereas the rolling would have.

The precession was violently increasing starting from 4:30. Roll or not roll it looked like the precession motion would have killed a vehicle soon enough. I'm no expert but it looked like the roll was either directly caused by the precession or had the same root cause with it. Maybe someone with more expertise then me can comment on that...