Author Topic: Centaur upper stage on Falcon 9  (Read 3244 times)

Online spacenut

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Centaur upper stage on Falcon 9
« on: 06/30/2015 06:34 pm »
I know rockets aren't Legos, and there are different companies, and priorities.  However in an extreme emergency, could the Centaur fly on Falcon 9?  And if so, what could it do to LEO and GTO?  Say for instance the unmanned x plane the Air Force uses if we can't get RD-180's in the next few years, or they need to launch something directly to GTO?

Offline Jim

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Re: Centaur upper stage on Falcon 9
« Reply #1 on: 06/30/2015 06:40 pm »
I know rockets aren't Legos, and there are different companies, and priorities.  However in an extreme emergency, could the Centaur fly on Falcon 9? 

No.
Pad doesn't have LH2 capability
Centaur doesn't like horizontal integration

Offline mikes

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Re: Centaur upper stage on Falcon 9
« Reply #2 on: 06/30/2015 07:01 pm »
Could LH2 be fed from a mobile bowser, or are the quantities required too large?

Offline Prober

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Re: Centaur upper stage on Falcon 9
« Reply #3 on: 06/30/2015 07:07 pm »
Musk and the Centaur don't play in the same sandbox  ;D
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Offline sdsds

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Re: Centaur upper stage on Falcon 9
« Reply #4 on: 06/30/2015 07:20 pm »
You're essentially asking, "Can anyone imagine a set of circumstances in which the need would be so urgent that the patently obvious and challenging obstacles could be overcome, with oodles of money?"

The answer is still, "No." No one can imagine circumstances like that. It is the policy of the United States that there would "always" be a better way. See "Assured Access to Space."
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Offline Jim

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Re: Centaur upper stage on Falcon 9
« Reply #5 on: 06/30/2015 07:24 pm »
Could LH2 be fed from a mobile bowser, or are the quantities required too large?

Tank is the easy part, need flare stack  and different plumbing (vacuum jacked) and valves.

Offline Burninate

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Re: Centaur upper stage on Falcon 9
« Reply #6 on: 07/01/2015 12:20 am »
I know rockets aren't Legos, and there are different companies, and priorities.  However in an extreme emergency, could the Centaur fly on Falcon 9?  And if so, what could it do to LEO and GTO?  Say for instance the unmanned x plane the Air Force uses if we can't get RD-180's in the next few years, or they need to launch something directly to GTO?

"In an extreme emergency", what's preventing you from doing anything in the way of rocket Legos?  The only stuff that an arbitrary supply of 1) money, and 2) tolerance for change & time to make changes, and 3) tolerance for risk doesn't knock down, is the baseline equations of spaceflight, and there's none of those *in the way* of Centaur specifically flying on Falcon 9 expendable, just an open question of how much payload it would achieve.  It would cost a lot of money, because F9 would have to be vertically integrated, requiring a whole new launch methodology for SpaceX, one which they had deliberately avoided for economic reasons.  It's implausible because there are better options, to start with the F9 upper stage, flown as part of a 2-stage vehicle named 'Falcon 9'.  These better options could be made ready faster, cheaper, and with less risk than Falcon-Centaur.

Here are the specs for Centaur in the Atlas V 551:
https://en.wikipedia.org/wiki/Centaur_(rocket_stage)#Specifications
20,830kg wet, 2,247kg dry.  99.2kN thrust at 451s Isp.  The Centaur would have to separate and burn before reaching orbit, since the F9's official stated payload capacity to orbit is 13,150kg, and unofficial estimates are IIRC 15-18T.   The thrust from the Centaur, which would permit half a G of acceleration at beginning of burn, is more than enough given how close this is to max payload (so separation would occur just shy of reaching orbit).

More analysis, answering what payload figures this would give you, is a bit too silly for me, given that this isn't going to happen.
« Last Edit: 07/01/2015 12:54 am by Burninate »

Offline nadreck

Re: Centaur upper stage on Falcon 9
« Reply #7 on: 07/01/2015 12:37 am »
I know rockets aren't Legos, and there are different companies, and priorities.  However in an extreme emergency, could the Centaur fly on Falcon 9?  And if so, what could it do to LEO and GTO?  Say for instance the unmanned x plane the Air Force uses if we can't get RD-180's in the next few years, or they need to launch something directly to GTO?

In an extreme emergency? No (as to me there is an implicit urgency in the concept of an extreme emergency)

If it was a matter of course where someone wanted to pay the money to put that in the stack, and there was plenty of time along with plenty of money. Then maybe it could be done, but it would probably not be the most sensible way to achieve whatever the goal for the ultimate payload that would sit on top of the Centaur.
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline intrepidpursuit

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Re: Centaur upper stage on Falcon 9
« Reply #8 on: 07/01/2015 03:56 am »
We all know if there is an extreme emergency we will just throw together a couple of titanium skinned hover shuttles and launch them in tandem.

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