Author Topic: SpaceX Crewed Dragon: Pressing home the advantage  (Read 219353 times)

Offline Lar

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #20 on: 01/10/2013 08:09 pm »
Great article Chris, really rooting for SpaceX on this one.

Regarding the April 2014 abort, what are they going to do to the Falcon 9 once they abort, are they going to carry on to orbit with a secondary payload, or are they going to have the RSO destruct the vehicle?

Maybe they could give OrbComm a cheap launch???... ya, probably not.
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Offline Joffan

Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #21 on: 01/10/2013 08:10 pm »
Great article Chris, really rooting for SpaceX on this one.

Regarding the April 2014 abort, what are they going to do to the Falcon 9 once they abort, are they going to carry on to orbit with a secondary payload, or are they going to have the RSO destruct the vehicle?

They'll fly it back to the pad, of course. ;)
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Offline guckyfan

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #22 on: 01/10/2013 08:12 pm »
Thanks for the article.

About rupture of the fuel dome. Is there newly released evidence for that happening? It was speculated as one possible reason for the engine failure but there were others like rupture of a fuel line.



OT, but my guess is that the rate of pressure fall is indicative - too large perhaps to what can be attributed to a fuel line.

I don't think it is OT, the rupture of the fuel dome is in the article, mentioned by Chris. I am aware that the rate of pressure fall can give evidence for the source of the rupture. I have followed all the threads and I did not see fuel dome rupture as the determined reason before this article. I may have missed it though. That is why I asked if the mention is based on newly released evidence.

Offline simonbp

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #23 on: 01/10/2013 08:19 pm »
We used to launch astronauts on ICBMs. Just sayin'.

EDIT:Actually, we still do. The R7 family started as an ICBM.

Yeah, though really, a modern Soyuz launcher has about as much to do with the original R-7 as an Atlas V has to do with an Atlas D.

Still though, the Titan IIs that Gemini used were only minimally modified from the ones in the silo with h-bombs.

Offline Chris Bergin

Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #24 on: 01/10/2013 08:24 pm »
Great article Chris, really rooting for SpaceX on this one.

Regarding the April 2014 abort, what are they going to do to the Falcon 9 once they abort, are they going to carry on to orbit with a secondary payload, or are they going to have the RSO destruct the vehicle?

Thanks and oooh, that's a good question. I'll see if I can find out.
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Offline hrissan

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #25 on: 01/10/2013 08:25 pm »
Great article Chris, really rooting for SpaceX on this one.

Regarding the April 2014 abort, what are they going to do to the Falcon 9 once they abort, are they going to carry on to orbit with a secondary payload, or are they going to have the RSO destruct the vehicle?
They'll fly it back to the pad, of course. ;)
I agree! :) They insisted on in-flight abort test because they bet they will get hardware back. They will probably use second stage simulator, right?

Offline Chris Bergin

Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #26 on: 01/10/2013 08:26 pm »
Great article Chris, really rooting for SpaceX on this one.

Regarding the April 2014 abort, what are they going to do to the Falcon 9 once they abort, are they going to carry on to orbit with a secondary payload, or are they going to have the RSO destruct the vehicle?

Thanks and oooh, that's a good question. I'll see if I can find out.
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Offline Robotbeat

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #27 on: 01/10/2013 08:29 pm »
We used to launch astronauts on ICBMs. Just sayin'.

EDIT:Actually, we still do. The R7 family started as an ICBM.

Yeah, though really, a modern Soyuz launcher has about as much to do with the original R-7 as an Atlas V has to do with an Atlas D.

Still though, the Titan IIs that Gemini used were only minimally modified from the ones in the silo with h-bombs.
The sides and the core stage is still the same basic design. The engine configuration is the same, the concept is all the same, the manufacturing techniques are similar (they use rivets, etc). Sure, it's been tweaked to all hell, but it definitely would be recognizable to the original designers.

Atlas V is a totally different rocket concept (first stage is not even balloon tanks anymore), totally different shape, totally different engines, etc.
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Offline GalacticIntruder

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #28 on: 01/10/2013 08:55 pm »
SpaceX is trying to be first, and should be.

No one on the panel wanted to touch the budget issue questions. We all know these companies are very optimistic on meeting their target dates just from a technical point of view; but we all know money will not be raining out of the sky, and that will be a big issue. Boeing of course could self fund, but probably won't. SpX wants to self-fund, but probably can't. Ed Mango all but begged these teams in the conference.

I was surprised by Blue Origin. They did not make cut but have some cool things. Maybe Bezos will throw in some more cash. He has much more than Musk.

 
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Offline butters

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #29 on: 01/10/2013 08:59 pm »
Great article Chris, really rooting for SpaceX on this one.

Regarding the April 2014 abort, what are they going to do to the Falcon 9 once they abort, are they going to carry on to orbit with a secondary payload, or are they going to have the RSO destruct the vehicle?

I doubt that any payload atop the second stage nestled inside the trunk barrel would survive a transonic abort because of the dynamic pressure. Air would rush into the trunk barrel after the capsule separates and almost certainly destroy any satellite residing there.

As for first stage RTLS, the transonic abort would occur at a significantly lower altitude than upper stage separation on the nominal flight trajectory. I doubt that the first stage structure would survive the flip to retrograde at that altitude. They need to get the first stage up and out of the sensible atmosphere to do the boost-back maneuver. And they can't just keep burning the stage because they need to demonstrate first stage shutdown as part of the abort demonstration.

I see no obvious alternative to a pure abort demo with no secondary payload and no stage recovery.

Offline JasonAW3

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #30 on: 01/10/2013 09:15 pm »
Heck,

     Blue Origine ought to design a moon and Mars landers, while Musk should concentrate on reusable Launchers (Yeah, full up rockets).

     Each team seems to have a certian expertise that the other could do well with, if they decided to work together.

     I'm not saying that they'll fail independantly of each other, but it would save them time and money to share some of each other's tech with the other.

Just sayin'

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Offline Karloss12

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #31 on: 01/10/2013 09:24 pm »
Great article Chris, really rooting for SpaceX on this one.

Regarding the April 2014 abort, what are they going to do to the Falcon 9 once they abort, are they going to carry on to orbit with a secondary payload, or are they going to have the RSO destruct the vehicle?

I doubt that any payload atop the second stage nestled inside the trunk barrel would survive a transonic abort because of the dynamic pressure. Air would rush into the trunk barrel after the capsule separates and almost certainly destroy any satellite residing there.

As for first stage RTLS, the transonic abort would occur at a significantly lower altitude than upper stage separation on the nominal flight trajectory. I doubt that the first stage structure would survive the flip to retrograde at that altitude. They need to get the first stage up and out of the sensible atmosphere to do the boost-back maneuver. And they can't just keep burning the stage because they need to demonstrate first stage shutdown as part of the abort demonstration.

I see no obvious alternative to a pure abort demo with no secondary payload and no stage recovery.

Instead of shutting down all Merlins could they just throttle the centre engine to minimum while the Dragon clears the core and then recover the 1st stage.  I expect it will involve a bit of persuading NASA that it won't affect the certification of the Dragon LAS.

As the 1st stage wouldn't be reaching its intended altitude and speed, would the 1st stage have to launch half empty as it wouldn't have enough time to expend the fuel through the centre engine in time?

Can F9 launch on half a tank?

Offline Lars_J

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #32 on: 01/10/2013 09:29 pm »
Instead of shutting down all Merlins could they just throttle the centre engine to minimum while the Dragon clears the core and then recover the 1st stage.  I expect it will involve a bit of persuading NASA that it won't affect the certification of the Dragon LAS.

I don't think so... They still need to get the 2nd stage off. (which will likely contain a full prop load to simulate real conditions)

And as stated above, the air hitting the trunk after Dragon abort will likely cause the trunk and 2nd stage to be torn apart, which will be bad news for the 1st stage as well.

Quote
Can F9 launch on half a tank?

Perhaps, but the test needs to be as close to real conditions as possible.
« Last Edit: 01/10/2013 09:29 pm by Lars_J »

Offline wolfpack

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #33 on: 01/10/2013 09:31 pm »
Regarding the April 2014 abort, what are they going to do to the Falcon 9 once they abort, are they going to carry on to orbit with a secondary payload, or are they going to have the RSO destruct the vehicle?

Can't see that as even being possible. Thrust termination occurs prior to or simultaneous with LAS motor ignition and capsule separation.

Offline wolfpack

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #34 on: 01/10/2013 09:36 pm »
Instead of shutting down all Merlins could they just throttle the centre engine to minimum while the Dragon clears the core and then recover the 1st stage.  I expect it will involve a bit of persuading NASA that it won't affect the certification of the Dragon LAS.

Why would you want to do this? It just increases the risk that the booster rams into the capsule, which is a test failure.

As the 1st stage wouldn't be reaching its intended altitude and speed, would the 1st stage have to launch half empty as it wouldn't have enough time to expend the fuel through the centre engine in time?

Can F9 launch on half a tank?

Sure, but again, what's the point of testing if you're going to perform the test in conditions that are guaranteed NOT to match an actual abort?

Offline IRobot

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #35 on: 01/10/2013 09:39 pm »
Unsure if they need a functional 2nd stage on the test. They could do it like the Apollo program, just a 1st stage. Or just put some weight to simulate the 2nd stage.

And I think SpaceX will try to persuade NASA to do a 1st stage recovery some seconds after the LAS test. Depends on how fast Grasshopper evolves.

Offline Okie_Steve

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #36 on: 01/10/2013 09:44 pm »
On the chance that it does not get shredded by aerodynamic forces after shutdown and separation at maxq how high would the falcon coast and what would the lateral velocity and atmospheric conditions be at the top? Anyone have an idea? Maybe there are some other useful tests that could be done even if flyback is not possible.

Offline oiorionsbelt

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #37 on: 01/10/2013 09:51 pm »
Nice article Chris.  Thanks for keeping us in the loop.

One question - What do you mean when you write the Dragon is 'partially crew-rated' ? 

Components may be "crew-rated", but the vehicle either is or isn't.

I'm just a systems / ops person, and easily confused.  Help me out here. ;)
It is fully human rated when berthed to the ISS

Offline Space Pete

Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #38 on: 01/10/2013 09:57 pm »
Could they combine the in-flight abort test with a test of the F9 first stage's ability to propulsively land? I.e. Dragon "punches off" of the F9 and lands, meanwhile the F9 also tests its boost-back and propulsive landing?
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Offline oiorionsbelt

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Re: SpaceX Crewed Dragon: Pressing home the advantage
« Reply #39 on: 01/10/2013 09:58 pm »
Sorry if this has been answered, but do the merlin engines need to be shut down before abort?

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