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SpaceX Falcon 1 Launch Attempt #2

Posted by: Klaus Schmidt - Wed Mar 14, 2007 4:32 pm
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SpaceX Falcon 1 Launch Attempt #2 

How far will the Falcon 1 get?
Launch pad failure 0%  0%  [ 0 ]
First stage failure 17%  17%  [ 3 ]
Successful seperation, but early second stage failure 11%  11%  [ 2 ]
Basically successful flight, only underperforming 28%  28%  [ 5 ]
Full success 44%  44%  [ 8 ]
Total votes : 18

SpaceX Falcon 1 Launch Attempt #2 
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Post    Posted on: Wed Mar 21, 2007 12:36 am
http://kwajrockets.blogspot.com/:
It looks like today's attempt will be pushed off. Pressure for the Main Chamber was 0.2% under the abort limit.

Missed by a hair...


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Post    Posted on: Wed Mar 21, 2007 12:42 am
The launch will go ahead VERY soon:
http://www.spacefellowship.com/News/?p=1929

in 10 minutes from now, we'll have a countdown again (if all is alright)

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Post    Posted on: Wed Mar 21, 2007 12:45 am
hmm webcast count down is still t-16


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Post    Posted on: Wed Mar 21, 2007 12:46 am
Restarts at 00:54 GMT (1:54 your time)

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Post    Posted on: Wed Mar 21, 2007 12:50 am
ahh cool!!!

i guess i'll have to hang on for a little while longer!!!


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Post    Posted on: Wed Mar 21, 2007 1:01 am
The webcast keeps cutting out on me. Sometimes I have to close the player and reconnect to get it going again. They don't seem to have enough bandwidth for the number of people watching.


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Post    Posted on: Wed Mar 21, 2007 1:10 am
Lucky you can always read 8)
http://www.spacefellowship.com/News/?p=1929

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Post    Posted on: Wed Mar 21, 2007 1:25 am
hmm wonder what has going on... it looked like the upper stage started to shake more and more


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Post    Posted on: Wed Mar 21, 2007 1:48 am
My take on the situation (quote is by me on another forum):

Also I noticed the stiffener ring at the aft edge of the krestel bell tear free after a few seconds of operation. At the time nobody said anything so I assumed it was normal, however now I'm begining to think this is what happened.

- Stages seperate, lower stage fairing gives a significant 'wang' to the end of the second stage motor nozzle bell, this damages the aft stiffener ring.
- Second stage engine ignites and forces on the aft stiffener causes it to break away, nozzle is still structurally sound but more flexible than it should be.
- Slight damage to the nozzle or CG shift causes the rocket thrust vector to be slightly off, gimbal accounts for this and fixes trajectory.
- The action of the gimbal causes the now weak aft end of the engine bell to flex, momentarily causing a large force in the opposite direction of the correction.
- As gimbal moves to correct this new force, the correction flexes the nozzle again, creating an even larger counter-force.

The cycle grows as we saw until either the nozzle bell fails, a safety overide shuts down the gimbal or the rocket tumbles.


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Post    Posted on: Wed Mar 21, 2007 1:56 am
http://www.spacefellowship.com/News/?p=1929

A press briefing of Elon Musk is online!

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Post    Posted on: Wed Mar 21, 2007 2:09 am
I thought they might have reduced thrust more gradually before seperation to minimize sloshing. The seperation itself was very odd.


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Post    Posted on: Wed Mar 21, 2007 2:33 am
It looks like the 2 people who voted for Successful seperation, but early second stage failure were right. :( Unfortunately there is no real way to test stage separation except in flight.


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Post mostly successful   Posted on: Wed Mar 21, 2007 3:13 am
Despite my disappointment that it wasn't a total success, I'm fairly happy with this launch. (though I'm unhappy that I couldn't watch it live...)

I think Elon's assessments were spot on. Yes, I'd expect nothing less than positive words from him, but I think he didn't overstate anything. It was a good day for SpaceX, maybe not a great day, but still a good one. Obviously they learned an awful lot from the first test flight.

I'm very impressed with the automatic sequencing and abort monitoring. It's not often that you see a rocket light up on the pad, abort and then fly successfully shortly thereafter.

I talked to my office mate who was part of the tech team for the flight 1 investigation. He was very happy with the performance, though obviously disappointed with the end results. SpaceX accomplished several difficult tasks flawlessly: stage 1 burn, max Q, payload fairing separation, stage separation, and stage 2 lit up nicely kept the rocket going until the flight termination.

It is unfortunate that telemetry was lost. I would think that the pre-loss telemetry is sufficient to determine what was going on prior to loss. I'm no comm expert, buy I'm curious if telemetry was lost due to sync problems during the oscillations.

It will be interesting to see if the control software couldn't compensate fast enough for the initial oscillation and thus induced further oscillations.

Again, I think this was a largely successful test launch. the first launch was quite a stumble. SpaceX pickup themselves up and made some great progress with this second flight. they've got some good talent.

I hope and expect they'll show improvement for Flight 3. I expect "third times a charm" (knock on wood) will work for SpaceX.

I wish them luck. I'm looking forward to the next launch and Falcon 9. It's time someone stuck it to BloMart (i.e. ULA)

- Alistair

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Post    Posted on: Wed Mar 21, 2007 3:23 am
Andrew Burns wrote:
My take on the situation (quote is by me on another forum):

Also I noticed the stiffener ring at the aft edge of the krestel bell tear free after a few seconds of operation. At the time nobody said anything so I assumed it was normal, however now I'm begining to think this is what happened.

- Stages seperate, lower stage fairing gives a significant 'wang' to the end of the second stage motor nozzle bell, this damages the aft stiffener ring.
- Second stage engine ignites and forces on the aft stiffener causes it to break away, nozzle is still structurally sound but more flexible than it should be.
- Slight damage to the nozzle or CG shift causes the rocket thrust vector to be slightly off, gimbal accounts for this and fixes trajectory.
- The action of the gimbal causes the now weak aft end of the engine bell to flex, momentarily causing a large force in the opposite direction of the correction.
- As gimbal moves to correct this new force, the correction flexes the nozzle again, creating an even larger counter-force.

The cycle grows as we saw until either the nozzle bell fails, a safety overide shuts down the gimbal or the rocket tumbles.


Stiffener rings are typically used for stiffness during ground transportation and usually serve no function during flight. I've seen stiffener rings separate on other launches with no effect on second stage performance.

Still, your speculation is reasonable. It's possible that the oscillation was initially well within controllable parameters but continued to slowly grow until it got out of controllable limits.

Hopefully this is a relatively easy fix. I want to see two more flights this year.

- Alistair

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Post    Posted on: Wed Mar 21, 2007 3:45 am
Enthusiast wrote:
I voted for "early second stage failure" because they can't test it on the ground nearly as well as the first stage. At least the first stage has flown once (although, of course, it failed).

I really hope I'm wrong, though! I can't wait for today's launch...


I'm sorry to say that I was right. I was really hoping for a full success. But it was still a fantastic flight! Up until the control anomaly everything seemed flawless.

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