Author Topic: General Falcon and Dragon discussion (Thread 13)  (Read 396561 times)

Offline mvpel

  • Full Member
  • ****
  • Posts: 1125
  • New Hampshire
  • Liked: 1303
  • Likes Given: 1685
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #520 on: 05/11/2016 03:44 pm »
*We* know nothing, apart from the fact that one engine in the OG-2 refire showed "thrust fluctuations".

I have it from a first-hand source that it was a very minor issue with a very easy fix.
"Ugly programs are like ugly suspension bridges: they're much more liable to collapse than pretty ones, because the way humans (especially engineer-humans) perceive beauty is intimately related to our ability to process and understand complexity. A language that makes it hard to write elegant code makes it hard to write good code." - Eric S. Raymond

Offline guckyfan

  • Senior Member
  • *****
  • Posts: 7438
  • Germany
  • Liked: 2332
  • Likes Given: 2891
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #521 on: 05/11/2016 05:11 pm »
I recently saw an old statement by Elon Musk. Very old, so very likely about 1.0 but should still be valid.

He said the thrust structure is very robust and has a practically unlimited life span. It is expensive enough that its recovery alone would be worth it.

Offline Barrie

  • Full Member
  • ****
  • Posts: 474
  • Planets are a waste of space
  • Liked: 242
  • Likes Given: 3815
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #522 on: 05/11/2016 07:37 pm »
I recently saw an old statement by Elon Musk. Very old, so very likely about 1.0 but should still be valid.

He said the thrust structure is very robust and has a practically unlimited life span. It is expensive enough that its recovery alone would be worth it.

iirc that was about Falcon 1

Offline rst

  • Full Member
  • ***
  • Posts: 347
  • Liked: 127
  • Likes Given: 0
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #523 on: 05/12/2016 04:03 pm »
I recently saw an old statement by Elon Musk. Very old, so very likely about 1.0 but should still be valid.

He said the thrust structure is very robust and has a practically unlimited life span. It is expensive enough that its recovery alone would be worth it.

On the other hand, the thrust structure and engine mounts seem to have been pretty heavily revised between F9 v1.0 and v1.1 -- from square to round arrangement, with the center engine lower, perhaps following the tank bulkheads.  There's still stuff in there which might have considerable value (e.g., blast walls between engine compartments), but statements about earlier models don't necessarily apply to v1.2, or FT, or whatever we're calling it this week.

Offline sojourner

  • Full Member
  • **
  • Posts: 253
  • Liked: 30
  • Likes Given: 1
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #524 on: 05/13/2016 05:29 am »
Last I had read, the 3 engine f9rdev2 was going to be used for the launch abort test of Dragon 2. Has that changed recently? I've read a few posts alluding to it no longer being used.

Offline Moderas

  • Member
  • Posts: 19
  • Illinois
  • Liked: 8
  • Likes Given: 2
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #525 on: 05/13/2016 02:15 pm »
If I recall correctly, it will no longer be used because it is not compatible with new infrastructure.

Offline Nilof

  • Full Member
  • ****
  • Posts: 1177
  • Liked: 597
  • Likes Given: 707
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #526 on: 05/14/2016 07:08 pm »
If I recall correctly, it will no longer be used because it is not compatible with new infrastructure.

Any chance that they'd do it with a reused core? If the core fails, you get a launch escape test with real-life conditions. ;D
« Last Edit: 05/14/2016 07:08 pm by Nilof »
For a variable Isp spacecraft running at constant power and constant acceleration, the mass ratio is linear in delta-v.   Δv = ve0(MR-1). Or equivalently: Δv = vef PMF. Also, this is energy-optimal for a fixed delta-v and mass ratio.

Offline mme

  • Full Member
  • ****
  • Posts: 1510
  • Santa Barbara, CA, USA, Earth, Solar System, Milky Way Galaxy, Virgo Supercluster
  • Liked: 2034
  • Likes Given: 5381
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #527 on: 05/14/2016 11:20 pm »
If I recall correctly, it will no longer be used because it is not compatible with new infrastructure.

Any chance that they'd do it with a reused core? If the core fails, you get a launch escape test with real-life conditions. ;D
There's been a lot of discussion about this.  I don't think they would risk using a core that would fail.  The test is for an abort at maximum dynamic pressure if I recall.  I think a failure before then is not really a valid test.  It's valid for generic in flight abort, but not maximum dynamic pressure abort. [1]

That said, I think that if SpaceX is confident that the stage will not fail prior to the abort then I can't think of a good reason not to use one now that F9-DevR is out of the picture.

[1] Yes, I am aware of Little John and NASA deciding that was "good enough."
Space is not Highlander.  There can, and will, be more than one.

Offline corrodedNut

  • Full Member
  • ****
  • Posts: 1542
  • Liked: 216
  • Likes Given: 133
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #528 on: 05/15/2016 06:35 pm »
Where is the CRS-9 thread?

"Our next Dragon departing HQ, ready for Florida"

https://www.instagram.com/p/BFXcK_Cl8cO/

Online gongora

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 10205
  • US
  • Liked: 13885
  • Likes Given: 5933
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #529 on: 05/15/2016 07:17 pm »
Where is the CRS-9 thread?

If a thread hasn't been created yet in the Missions section you can make one yourself, one of the mods will clean up the formatting when they start paying attention to that mission.

Offline WizZifnab

  • Member
  • Posts: 33
  • Kentucky
  • Liked: 5
  • Likes Given: 20
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #530 on: 05/16/2016 12:38 am »
If I recall correctly, it will no longer be used because it is not compatible with new infrastructure.

Any chance that they'd do it with a reused core? If the core fails, you get a launch escape test with real-life conditions. ;D
There's been a lot of discussion about this.  I don't think they would risk using a core that would fail.  The test is for an abort at maximum dynamic pressure if I recall.  I think a failure before then is not really a valid test.  It's valid for generic in flight abort, but not maximum dynamic pressure abort. [1]

That said, I think that if SpaceX is confident that the stage will not fail prior to the abort then I can't think of a good reason not to use one now that F9-DevR is out of the picture.

[1] Yes, I am aware of Little John and NASA deciding that was "good enough."

If a used core is ready in time and deemed flight worthy seems reasonable to use it.  Does the flight profile allow for booster recovery?  If not, a used core would seem preferable.

Is there some SpaceX reference to not using the F9DevR? Or is that an assumption based on changed infrastructure at the Vandenburg pad?  Is there definitely no way to use the F9-DevR?  Again, if the flight profile doesn't allow booster recovery this would seem to be preferable over using even a used booster in my opinion.

Offline The Amazing Catstronaut

  • Full Member
  • ****
  • Posts: 1065
  • Arsia Mons, Mars, Sol IV, Inner Solar Solar System, Sol system.
  • Liked: 759
  • Likes Given: 626
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #531 on: 05/16/2016 12:40 am »
https://twitter.com/elonmusk/status/731984739012251648

Synopsis of the tweet: Most recently recovered stage (from JSCAT-14) is not going to be relaunched. Instead, it's going to be tested extensively and used as a benchmark against which the conditions of other stages are measured.

Effectively, it's going to provide a lot of good data. I get the impression that it's better toasted than raw at this stage.
Resident feline spaceflight expert. Knows nothing of value about human spaceflight.

Offline catdlr

  • Member
  • Senior Member
  • *****
  • Posts: 11169
  • Enthusiast since the Redstones
  • Marina del Rey, California, USA
  • Liked: 8785
  • Likes Given: 7815
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #532 on: 05/16/2016 01:25 am »
Where is the CRS-9 thread?

If a thread hasn't been created yet in the Missions section you can make one yourself, one of the mods will clean up the formatting when they start paying attention to that mission.

Done: http://forum.nasaspaceflight.com/index.php?topic=40310.0
Tony De La Rosa, ...I'm no Feline Dealer!! I move mountains.  but I'm better known for "I think it's highly sexual." Japanese to English Translation.

Offline Ilikeboosterrockets

  • Full Member
  • *
  • Posts: 130
  • Liked: 88
  • Likes Given: 34
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #533 on: 05/16/2016 11:40 am »
Random question: How does the Dragon eject its nose cone on ascent?

Offline mfck

  • Office Plankton Representative
  • Full Member
  • ****
  • Posts: 543
  • Israel
  • Liked: 254
  • Likes Given: 222
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #534 on: 05/16/2016 06:50 pm »


If I recall correctly, it will no longer be used because it is not compatible with new infrastructure.

Any chance that they'd do it with a reused core? If the core fails, you get a launch escape test with real-life conditions. ;D
There's been a lot of discussion about this.  I don't think they would risk using a core that would fail.  The test is for an abort at maximum dynamic pressure if I recall.  I think a failure before then is not really a valid test.  It's valid for generic in flight abort, but not maximum dynamic pressure abort. [1]

That said, I think that if SpaceX is confident that the stage will not fail prior to the abort then I can't think of a good reason not to use one now that F9-DevR is out of the picture.

[1] Yes, I am aware of Little John and NASA deciding that was "good enough."

If a used core is ready in time and deemed flight worthy seems reasonable to use it.  Does the flight profile allow for booster recovery?  If not, a used core would seem preferable.

Is there some SpaceX reference to not using the F9DevR? Or is that an assumption based on changed infrastructure at the Vandenburg pad?  Is there definitely no way to use the F9-DevR?  Again, if the flight profile doesn't allow booster recovery this would seem to be preferable over using even a used booster in my opinion.

F9RDev2 is incompatible with FT pads and won't be used. IIRC it is not an assumption and has been confirmed with SX.

Online Prettz

  • Full Member
  • ****
  • Posts: 497
  • O'Neillian
  • Atlanta, GA
  • Liked: 259
  • Likes Given: 30
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #535 on: 05/17/2016 03:21 pm »
So is that core now just a complete write-off? What a waste.

Offline mme

  • Full Member
  • ****
  • Posts: 1510
  • Santa Barbara, CA, USA, Earth, Solar System, Milky Way Galaxy, Virgo Supercluster
  • Liked: 2034
  • Likes Given: 5381
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #536 on: 05/17/2016 03:35 pm »
So is that core now just a complete write-off? What a waste.
As others have pointed out, SpaceX doesn't buy into the sunk cost fallacy.  If they did, they'd still be trying to recover boosters with parachutes. :)
Space is not Highlander.  There can, and will, be more than one.

Offline mvpel

  • Full Member
  • ****
  • Posts: 1125
  • New Hampshire
  • Liked: 1303
  • Likes Given: 1685
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #537 on: 05/17/2016 03:49 pm »
So is that core now just a complete write-off? What a waste.

It'll look really good next to Endeavor at the California Science Center.
"Ugly programs are like ugly suspension bridges: they're much more liable to collapse than pretty ones, because the way humans (especially engineer-humans) perceive beauty is intimately related to our ability to process and understand complexity. A language that makes it hard to write elegant code makes it hard to write good code." - Eric S. Raymond

Offline cscott

  • Senior Member
  • *****
  • Posts: 3471
  • Liked: 2867
  • Likes Given: 726
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #538 on: 05/17/2016 04:35 pm »
So is that core now just a complete write-off? What a waste.

It'll look really good next to Endeavor at the California Science Center.
So long as the KSC rocket garden gets the CRS-8 core.  (Hawthorne's getting OG2, as we know.)

The F9dev core was used for fit checks at Vandenberg and probably other testing/pathfinder work, so it wasn't a complete waste.
« Last Edit: 05/17/2016 04:37 pm by cscott »

Online Prettz

  • Full Member
  • ****
  • Posts: 497
  • O'Neillian
  • Atlanta, GA
  • Liked: 259
  • Likes Given: 30
Re: General Falcon and Dragon discussion (Thread 13)
« Reply #539 on: 05/17/2016 06:32 pm »
So is that core now just a complete write-off? What a waste.
As others have pointed out, SpaceX doesn't buy into the sunk cost fallacy.  If they did, they'd still be trying to recover boosters with parachutes. :)
Sure, but they never actually used this one for any testing. So it really is a waste.

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
0