Author Topic: DARPA Experimental Spaceplane 1 (XS-1) Program  (Read 280711 times)

Offline Robotbeat

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #40 on: 09/16/2013 08:51 AM »
Don't forget Blue Origin, who has more experience with fast turnaround than SpaceX does and is working on a hydrolox VTVL first stage.
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Offline ChrisWilson68

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #41 on: 09/16/2013 09:18 AM »
Sure, Blue Origin could also be getting to that point.  But it's a lot harder to tell with them since they keep everything so quiet and don't have or want (at this point) any customers.  Has Blue Origin already built a vehicle that they think can reach Mach 10 and then land again?  I have no idea.

Offline a_langwich

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #42 on: 09/16/2013 09:24 AM »
Rascal had pretty good program requirements as well.

The question is how DARPA avoids the X-33/RASCAL  trap of picking a winner who can't actually meet the requirements.

DARPA can avoid that by setting requirements more conservatively, but then they wouldn't be DARPA.  It's absolutely necessary and expected that they take big risks.  Problems are expected, failures aren't completely surprising.  The object is to get enough high-payout successes to offset a fair number of failures made cheaper by careful monitoring and early cutoff.

A core part of RASCAL was as Jon Goff described:  MIPCC on the aircraft first stage, which pre-injects water and LOX in front of a standard F100-PW-200 engine.  Staging occurred at a Mach 3-ish pullup maneuver.  I don't think MIPCC could stretch much further than that.  Mach 10 is right out.

A custom-designed, fairly large Mach 3 aircraft is no small task.  I'm not at all surprised it was looking like it would take more than $100 million, which was more than DARPA wanted to spend.  (I'm saying it wasn't the contractor's fault.)  All the traditional aerospace companies who have experience in Mach 2+ aircraft would laugh at that price.

Back on the XS-1, I agree with Jon, Mach 10 is very ambitious.  For a rocket, that's going to be really high and fast and far downrange to recover.  For an aircraft...well, there's been only one aircraft ever to do that, right?  If you count Mach 9.65 as close enough.  (I'm considering the shuttle to be a rocket passing through that region.)  And the X-43 program cost $230 million according to wikipedia, had no payload, essentially no ability to operate itself outside the hypersonic region, and produced 3 flights, only one of which approached Mach 10.  Hmm, the rocket option is looking better and better.

Offline a_langwich

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #43 on: 09/16/2013 09:29 AM »
Don't forget Blue Origin, who has more experience with fast turnaround than SpaceX does and is working on a hydrolox VTVL first stage.

More experience with fast turnaround?  How many flight tests have they performed?  How many since the vehicle crash?  Have they tested more times than Grasshopper since then?

Offline Robotbeat

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #44 on: 09/16/2013 05:38 PM »
Don't forget Blue Origin, who has more experience with fast turnaround than SpaceX does and is working on a hydrolox VTVL first stage.

More experience with fast turnaround?  How many flight tests have they performed?
A LOT, with several vehicles starting with a jet engine platform, moving to hydrogen peroxide and kerosene/peroxide. They have had several test vehicles. Easily tested far more times than Grasshopper.
Quote
How many since the vehicle crash?  Have they tested more times than Grasshopper since then?
Kind of irrelevant since I was talking about past experience, since they switched over to development of their subscale hydrolox booster (will form basis of the upper stage of their launch vehicle as well as being a path-finder for the first stage). They've had good test-firings of their turbopump-fed hydrolox engine (the first such totally new US hydrolox engine in a long time) and are working on the tank for the subscale booster right now.

It's certainly possible they've done more VTVL testing since then. They're very secretive. But regardless, they have much more VTVL experience than SpaceX does (although SpaceX is operating at large scale).

If you want more info, here's their update thread:
http://forum.nasaspaceflight.com/index.php?topic=10685.700
« Last Edit: 09/16/2013 05:38 PM by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Zond

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #45 on: 09/16/2013 05:55 PM »
Don't forget Blue Origin, who has more experience with fast turnaround than SpaceX does and is working on a hydrolox VTVL first stage.

More experience with fast turnaround?  How many flight tests have they performed?
A LOT, with several vehicles starting with a jet engine platform, moving to hydrogen peroxide and kerosene/peroxide. They have had several test vehicles. Easily tested far more times than Grasshopper.
There's no evidence Blue Origin has made more then 7 flights (1 by Charon, 3 by Godddard, 2 by PM2 and one pad escape test). Wikipedia lists them all: http://en.wikipedia.org/wiki/Blue_Origin.
That's the same as the amount of flights Grasshopper has made.

Offline john smith 19

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #46 on: 09/16/2013 10:01 PM »
Remember, this is DARPA that we're talking about.

     Someone in the military must think that the fast turn around maybe needed and is assuming that payloads for such a quick succession of launches would be available. Or more precisely, be required.   I don't know of any mass production line of satillites going on, but it doesn't mean that they couldn't have other payloads in mind.

Well, knowing Jess Sponable's past history, here's my hunch. By requiring 10 flights in 10 days of the first stage, you pretty much guarantee that the per flight maintenance for that stage has to be low. You might be able to get away with doing two flights back to back by scrimping on needed maintenance, but if you're talking 10 flights back to back to back, that's hard to do unless the actually maintenance per flight is really low--which is a real key to keeping an RLV's cost down.

Right now, when people look at "RLVs" like shuttle, they see something that takes weeks or months to turn around, and that would be hard pressed to get 50flts/yr on an airframe even if there were payloads for it. If you have something that can really do 10 flights in 10 days, that's pushing a lot closer to the sub one week normal operations turnaround that is needed to get the flight rates for the economics to really do interesting things.
~Jon

It's good to hear that Sponable will be in charge of this, but another obvious key question is how big is the budget?

IIRC DC-X could hit M3 at a price of $60m, as can SS2, but at considerably higher cost I know, bigger payload, certified for paying passengers etc, but I think there is a point that wings do need more design work up front.

So doable with rockets at a "relatively" low price.

Air breathing I think will need to put a lot more cash on the table unless they can get something close to a flyable airframe, that already exists from somewhere.

Where does one get an M10 winged airframe (that's 1.5x the top sped of an X15) in a hurry?  I've no idea.  :(

OTOH if this is a launcher then a design that can handle M10 for minutes should be good enough to get the the job done, and that opens various options (different people will have their preferences). But operability and maintainability....

If Sponable is playing X plane rules "best simple" wins, however there is a wrinkle that they might consider.

The RENE concept put a divergent duct around a rocket engine. This gave a 55% boost in thrust roughly in the M0-M2 range using a fixed duct geometry that needed no more than 3x the mass flow of the core rocket (earlier concepts worked around 20x that). There is also the idea of "thermal choke" to give a sort of "virtual nozzle" effect that can be controlled by fuel flow.

That (in principal) gives a simple (fixed element) low area (hence low mass) inlet design that gives a substantial thrust boost just when the vehicle will be heaviest. If all the new stuff weighs < 50% of the engine dry mass you're ahead of the game. More risky but high payoff.

BTW let me ask a really dumb question.

M10 Horizontal or M10 vertical?

Because it does not say on the slides and you know what they say about "assuming" things  :)

A truly open competition should produce some interesting submissions. I just hope they focus on the goal, rather than the technology.
« Last Edit: 09/16/2013 10:15 PM by john smith 19 »
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Offline jongoff

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #47 on: 09/18/2013 06:32 AM »
New info:
https://www.fbo.gov/utils/view?id=e66b00991b0418e815627bd9e7688aa3

There will be a proposer's day on the 7th and 8th of October in DC (need to register in advance if you want to attend).

Also, apparently the Mach10 number is not the normal staging velocity, but a "we want to reach this speed with the stage at least once".  I don't know if they require you to get to Mach 10 and reenter without doing retropropulsion, or if they would be ok with basically a stunt demonstrating that capability. But by not having the actual staging velocity at Mach 10, this seems to be a lot more likely to get a broad range of ideas proposed. Hopefully this results in flight hardware.

More thoughts tomorrow maybe.

~Jon

Offline john smith 19

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #48 on: 09/18/2013 08:08 AM »
New info:
https://www.fbo.gov/utils/view?id=e66b00991b0418e815627bd9e7688aa3

There will be a proposer's day on the 7th and 8th of October in DC (need to register in advance if you want to attend).
OK the document seems to make things a bit clearer.

I guess (and this will sound quite stupid) it depends what you mean by "aircraft."

The common understanding is a crewed powered HTHL winged vehicle taking off from a runway and returning to it. But as people here know the full range of vehicles that term could cover is much wider.

The trouble is that (common definition) pretty much drops out all the cheapest options IE rocket based vertical launch. OTOH later it merely asks for "aircraft like" operations, so maybe they are back in?

That single test to M10 su