Author Topic: SpaceX COTS Demo 1 Updates  (Read 675812 times)

Offline docmordrid

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Re: COTS Demo 1
« Reply #880 on: 12/07/2010 09:47 pm »
Nice to know there's enough margin that it can spare that much, isn't it ;)
DM

Offline PahTo

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Re: COTS Demo 1
« Reply #881 on: 12/07/2010 09:50 pm »

I was thinking the same thing.  Now I wonder if the nozzle "repair" would be an issue if they were launching to a 51.6 inclination...

Nice to know there's enough margin that it can spare that much, isn't it ;)

Offline Kabloona

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Re: COTS Demo 1
« Reply #882 on: 12/07/2010 09:51 pm »
Nice to know there's enough margin that it can spare that much, isn't it ;)

I guess they used more than a Dremel...sounds like this was a job for the SawzAll!
« Last Edit: 12/07/2010 09:52 pm by Kabloona »

Online jabe

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Re: COTS Demo 1
« Reply #883 on: 12/07/2010 09:54 pm »
curious to see how they did it?  stiffener ring i guess isn't needed since it really isn;t being moved much except straight up ;)
jb

Offline robertross

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Re: COTS Demo 1
« Reply #884 on: 12/07/2010 09:55 pm »
Quote:

"The long-awaited first launch, which was delayed a day by cracks in the nozzle of the upper-stage engine of the company's Falcon 9 rocket, was set after engineers decided that they could get rid of the cracks by trimming a few feet off the nozzle extension without significantly impacting the performance of the rocket, according to company sources."

A few feet? LOL. Try "inches."

Nope, a few feet is correct.  That isn't a typo.

As in, a few feet of length???? Holy moly...please elaborate.

To save bandwidth, from the picture on this post:
http://forum.nasaspaceflight.com/index.php?topic=22041.msg667323#msg667323

they must be lopping the bell off at the lowest weld joint (probably just below it).
Perfect line to follow ;)

I was shocked too at the 'few feet' comment, but at 9 feet tall, taking maybe 3 feet off probably isn't at any critical point on the curve. Closer to throat, absolutely, but out near the nozzle's end, probably a 5% hit (guesstimate).

Offline Chandonn

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Re: COTS Demo 1
« Reply #885 on: 12/07/2010 09:55 pm »
Nice to know there's enough margin that it can spare that much, isn't it ;)

I guess they used more than a Dremel...sounds like this was a job for the SawzAll!

... available at your local Spaceport Depot Store, next to the glue gun and the Duct Tape!

;)

Offline Kabloona

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Re: COTS Demo 1
« Reply #886 on: 12/07/2010 10:01 pm »
Quote:

"The long-awaited first launch, which was delayed a day by cracks in the nozzle of the upper-stage engine of the company's Falcon 9 rocket, was set after engineers decided that they could get rid of the cracks by trimming a few feet off the nozzle extension without significantly impacting the performance of the rocket, according to company sources."

A few feet? LOL. Try "inches."

Nope, a few feet is correct.  That isn't a typo.

As in, a few feet of length???? Holy moly...please elaborate.

To save bandwidth, from the picture on this post:
http://forum.nasaspaceflight.com/index.php?topic=22041.msg667323#msg667323

they must be lopping the bell off at the lowest weld joint (probably just below it).
Perfect line to follow ;)

I was shocked too at the 'few feet' comment, but at 9 feet tall, taking maybe 3 feet off probably isn't at any critical point on the curve. Closer to throat, absolutely, but out near the nozzle's end, probably a 5% hit (guesstimate).


Well, and it's also a thermal issue because now you have a plume expanding "feet" closer than to the aft end of the stage than designed...hope they have plenty of insulation there! And there was that thermal issue last time on S2...
« Last Edit: 12/07/2010 10:03 pm by Kabloona »

Offline Mapperuo

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Re: COTS Demo 1
« Reply #887 on: 12/07/2010 10:02 pm »
Quite shocked they have chosen to lop the end off rather than wait to get a new one which I thought they could get easily for Thursday?
- Aaron

Offline Chris Bergin

Re: COTS Demo 1
« Reply #888 on: 12/07/2010 10:03 pm »
Not cleared for launch just yet....

SpaceX to media: "SpaceX engineers are currently performing their final inspections before launch.  So far everything looks good, but we won't have the final all-clear until around 9PM EST.

Watch for updates."
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Offline SpaceX_MS

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Re: COTS Demo 1
« Reply #889 on: 12/07/2010 10:06 pm »
That had to be put out as we've no idea why NASA would say we're already a go. We're close to it, but not yet.

Offline Kabloona

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Re: COTS Demo 1
« Reply #890 on: 12/07/2010 10:08 pm »
That had to be put out as we've no idea why NASA would say we're already a go. We're close to it, but not yet.

SpaceX, can you provide any further details on the nozzle mod process?

Offline Chris Bergin

Re: COTS Demo 1
« Reply #891 on: 12/07/2010 10:09 pm »
That had to be put out as we've no idea why NASA would say we're already a go. We're close to it, but not yet.

NASA seem convinced :)

Dec. 7, 2010

Michael Braukus
Headquarters, Washington
202-358-1979
[email protected]

George H. Diller
Kennedy Space Center, Fla.
321-867-2468
[email protected]

Josh Byerly
Johnson Space Center, Houston
281-483-5111
[email protected]

MEDIA ADVISORY: M10-170

DEMONSTRATION FLIGHT OF FALCON 9 ROCKET SET FOR WEDNESDAY

CAPE CANAVERAL, Fla. -- The first demonstration flight of SpaceX's
Falcon 9 rocket and Dragon capsule for NASA's Commercial Orbital
Transportation Services program has been scheduled for Wednesday,
Dec. 8, from Cape Canaveral Air Force Station in Florida. The launch
window extends from 9 a.m. to 12:22 p.m. EST.

During a routine inspection this week, SpaceX engineers observed two
small cracks in the rocket's second stage engine nozzle. SpaceX
completed repairs to the cracked nozzle Tuesday.

Live coverage of the launch will air on NASA Television and the
agency's website. For streaming information, visit:



http://www.nasa.gov/ntv


For more information about the launch, visit:



http://www.nasa.gov/cots

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Online ugordan

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Re: COTS Demo 1
« Reply #892 on: 12/07/2010 10:30 pm »
Well, and it's also a thermal issue because now you have a plume expanding "feet" closer than to the aft end of the stage than designed...hope they have plenty of insulation there! And there was that thermal issue last time on S2...

Yes, even the smallest change can come back and bite you when it comes to rockets. I hope they thought this over well, they already have experience with "small" changes.

Apparently it's a 4-foot section of the nozzle.

Offline HOTTOL

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Re: COTS Demo 1
« Reply #893 on: 12/07/2010 10:33 pm »
Quoting SPACEFLIGHT NOW -Falcon 9 launch timeline
"T+09:35 Dragon Separation
The Dragon capsule separates from the second stage, leaving behind its unpressurized trunk section, which contains secondary CubeSat payloads."

1- Do they mean the trunk will split from Dragon capsule right at Stage 2 sep. ?
In this case the rest of the in-space operations would be made without the trunk attached to Dragon !
2- If yes, how will they separate the trunk from the second stage once Dragon has gone away ?
3- How will they release the Cube Sats which are said to be in the trunk ?

Offline Kabloona

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Re: COTS Demo 1
« Reply #894 on: 12/07/2010 10:35 pm »
Well, and it's also a thermal issue because now you have a plume expanding "feet" closer than to the aft end of the stage than designed...hope they have plenty of insulation there! And there was that thermal issue last time on S2...

Yes, even the smallest change can come back and bite you when it comes to rockets. I hope they thought this over well, they already have experience with "small" changes.

Apparently it's a 4-foot section of the nozzle.

Wow, that is non-trivial. These guys are smarter than I am, but I sure hope they did their homework...with a very sharp pencil.
« Last Edit: 12/07/2010 10:37 pm by Kabloona »

Offline jimvela

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Re: COTS Demo 1
« Reply #895 on: 12/07/2010 10:36 pm »
Nice to know there's enough margin that it can spare that much, isn't it ;)

Now we get to learn a bit more about SpaceX.

For example, is the vehicle and (most importantly) FSW ready to deal with a few percent underperformance of the second stage?

Do they just update tables, or spin a whole new FSW build?  IF a new build, how do they QA the new build.  For that matter, how do they handle QA of the overall system configuration of the now-modified integrated vehicle?

Images of Ariane 5 501 pop into mind...

« Last Edit: 12/07/2010 10:43 pm by jimvela »

Offline robertross

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Re: COTS Demo 1
« Reply #896 on: 12/07/2010 10:38 pm »

Well, and it's also a thermal issue because now you have a plume expanding "feet" closer than to the aft end of the stage than designed...hope they have plenty of insulation there! And there was that thermal issue last time on S2...

Very true. Although the radiant heat from the nozzle is also always there.

There will probably be some charring. But it is a 'test flight' after all, and very short.

Rough sketch attached.

Online ugordan

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Re: COTS Demo 1
« Reply #897 on: 12/07/2010 10:40 pm »
For example, is the vehicle and (most importantly) FSW ready to deal with a few percent underperformance of the second stage?

One would think the first flight was just as uncertain performance-wise. The devil is in the details, though.

Offline Kabloona

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Re: COTS Demo 1
« Reply #898 on: 12/07/2010 10:45 pm »

Well, and it's also a thermal issue because now you have a plume expanding "feet" closer than to the aft end of the stage than designed...hope they have plenty of insulation there! And there was that thermal issue last time on S2...

Very true. Although the radiant heat from the nozzle is also always there.

There will probably be some charring. But it is a 'test flight' after all, and very short.

Rough sketch attached.

Correct, and maybe the heating delta is negligible, but remember that in vacuum the plume expands essentially to infinity, so the plume angle in your sketch will increase to basically vertical...

Offline PahTo

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Re: COTS Demo 1
« Reply #899 on: 12/07/2010 10:53 pm »

It occurs to me that this repair has the added benefit of reducing the chances of nozzle contact at staging...
Still more than a meter gone--almost 50% of the length--whew.

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