Author Topic: DARPA Experimental Spaceplane 1 (XS-1) Program  (Read 193824 times)

Offline jongoff

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #20 on: 09/13/2013 05:14 PM »
May be they mentioned that it has to reach Mach 10 by itself (i.e. no US nor payload)? Which I think is sort of normal for expendable version.

Yes. Mach 10 for the first stage or the plane.

Just to be clear, the Mach 10 requirement may be met by either the reusable booster (before staging) or the expendable stage (after staging)?

Thanks for any clarification.

From the briefing it sounded to me like the Mach 10 requirement was for the reusable booster before staging.

~Jon

Offline Danderman

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #21 on: 09/13/2013 05:35 PM »
It sounds like someone at DARPA has concluded that the problem with RASCAL was the team selected as the winner, and not the program requirements.

It would be interesting for someone to start up a  new topic on the history of the RASCAL program, for the purposes of comparing and contrasting RASCAL with XS-1.

Offline darkbluenine

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #22 on: 09/13/2013 06:11 PM »
From the briefing it sounded to me like the Mach 10 requirement was for the reusable booster before staging.

That's disappointing.  I'll have to listen to the recording.

The flight rate requirements on the XS-1 slide above also seem contradictory.  The test requirement is high at 10 flights in 10 days, but the system's recurring costs goals are based around a very low operational flight rate of 10 flights per year.

Online Robotbeat

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #23 on: 09/13/2013 06:33 PM »
From the briefing it sounded to me like the Mach 10 requirement was for the reusable booster before staging.

That's disappointing.  I'll have to listen to the recording.

The flight rate requirements on the XS-1 slide above also seem contradictory.  The test requirement is high at 10 flights in 10 days, but the system's recurring costs goals are based around a very low operational flight rate of 10 flights per year.
That's not contradictory. It's conservative.
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Offline darkbluenine

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #24 on: 09/13/2013 06:42 PM »
The flight rate requirements on the XS-1 slide above also seem contradictory.  The test requirement is high at 10 flights in 10 days, but the system's recurring costs goals are based around a very low operational flight rate of 10 flights per year.
That's not contradictory. It's conservative.

I get that the annual flight rate is conservative.  But the test requirement is very aggressive.  It's either going to pull the development in two different, contradictory, potentially incompatible directions.  Or the government is going to pay a lot to develop something it doesn't need -- a highly operational vehicle in the absence of payloads and missions to exploit the vehicle's high operational tempo.

It's like the XS-1 is trying to be the spaceplane equivalent of an Antares and an F9R at the same time.  Only with an even greater difference in flight rate.

Offline JasonAW3

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #25 on: 09/13/2013 06:45 PM »
I'm wondering if they are considering tying the Air Force's current autonamous spaceplane to this system.

     I haven't seen it mentioned, so, does anyone have an idea of what the target payload mass (ie upper stage) is yet?

     Seeing some of his comnments on reusables in the past, I'm rather suprised that Jim hasn't made a comment here yet.

Jason
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Offline JasonAW3

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #26 on: 09/13/2013 06:55 PM »
The flight rate requirements on the XS-1 slide above also seem contradictory.  The test requirement is high at 10 flights in 10 days, but the system's recurring costs goals are based around a very low operational flight rate of 10 flights per year.
That's not contradictory. It's conservative.

I get that the annual flight rate is conservative.  But the test requirement is very aggressive.  It's either going to pull the development in two different, contradictory, potentially incompatible directions.  Or the government is going to pay a lot to develop something it doesn't need -- a highly operational vehicle in the absence of payloads and missions to exploit the vehicle's high operational tempo.

It's like the XS-1 is trying to be the spaceplane equivalent of an Antares and an F9R at the same time.  Only with an even greater difference in flight rate.

I'm not really sure I can agree with you on the operational tempo.

      The use of a high altitude nuclear blast would take out a major number of satillites, both civilian and military.  Getting the holes in both the GPS system patched and replacing at least some of the military CNC and surveilance sats would prove critical in this kind of scenerio.  Plus the ability to loft low cost single use surveilance sats at random intervals would avoid the issues of an enemy knowing the satilite schedule, like many of our enemies do, and being able to hide what they don't want us to see.

     Of course, someone could have gone nuts and decided to build VaunBraun's rotating spacestation, and thius would be the fastest way of getting it don before Congress cuts the funding for it...

Jason
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Online Robotbeat

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #27 on: 09/13/2013 07:54 PM »
The flight rate requirements on the XS-1 slide above also seem contradictory.  The test requirement is high at 10 flights in 10 days, but the system's recurring costs goals are based around a very low operational flight rate of 10 flights per year.
That's not contradictory. It's conservative.

I get that the annual flight rate is conservative.  But the test requirement is very aggressive.  It's either going to pull the development in two different, contradictory, potentially incompatible directions.  Or the government is going to pay a lot to develop something it doesn't need -- a highly operational vehicle in the absence of payloads and missions to exploit the vehicle's high operational tempo.
...
There aren't payloads enough for a highly operational vehicle until the price can be brought down by a highly operational vehicle. The only way to break this paradox is to make a vehicle viable at both ends of the spectrum. IMHO.
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Offline JasonAW3

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #28 on: 09/13/2013 08:07 PM »
There aren't payloads enough for a highly operational vehicle until the price can be brought down by a highly operational vehicle. The only way to break this paradox is to make a vehicle viable at both ends of the spectrum. IMHO.

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.

Jason
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Offline jongoff

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #29 on: 09/13/2013 08:50 PM »
There aren't payloads enough for a highly operational vehicle until the price can be brought down by a highly operational vehicle. The only way to break this paradox is to make a vehicle viable at both ends of the spectrum. IMHO.

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

Offline jongoff

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #30 on: 09/13/2013 08:51 PM »
It sounds like someone at DARPA has concluded that the problem with RASCAL was the team selected as the winner, and not the program requirements.

It would be interesting for someone to start up a  new topic on the history of the RASCAL program, for the purposes of comparing and contrasting RASCAL with XS-1.

I thought RASCAL was an air-launched rocket concept where they were using some LOX injection in the jet stage's engines to allow a low-subsonic staging velocity...this seems at least to me to be fairly different.

~Jon

Offline Danderman

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #31 on: 09/14/2013 12:01 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.

Offline dkovacic

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #32 on: 09/14/2013 07:55 AM »
It seems to me that grasshopper 2 / 1st stage of F9R could easily fullfil these requirements. Is it likely that spacex would participate in this program?

Offline jongoff

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #33 on: 09/14/2013 02:27 PM »
It seems to me that grasshopper 2 / 1st stage of F9R could easily fullfil these requirements. Is it likely that spacex would participate in this program?

I'm actually not sure about that. What's F9R's staging velocity? I thought it was quite a bit short of Mach 10, something like Mach 6 or so. That said, with a much smaller upper stage on it (optimized for a 1-4klb payload), it *might* be able to do it. But then, do people really think F9R can turn around 10x in 10 days after doing a full Mach10 flight? Maybe. But I'm not totally sure.

~Jon

Offline JasonAW3

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #34 on: 09/14/2013 10:13 PM »
It seems to me that grasshopper 2 / 1st stage of F9R could easily fullfil these requirements. Is it likely that spacex would participate in this program?

I'm actually not sure about that. What's F9R's staging velocity? I thought it was quite a bit short of Mach 10, something like Mach 6 or so. That said, with a much smaller upper stage on it (optimized for a 1-4klb payload), it *might* be able to do it. But then, do people really think F9R can turn around 10x in 10 days after doing a full Mach10 flight? Maybe. But I'm not totally sure.

~Jon

      Didn't think about it until now, but a Mach 10 staging ability sounds an awful lot like they're thinking of a hypersonic missile or bomber launcher.

      if we had a better idea of the payload requirements, we'd have a better idea of what they want such an RLV for.

Jason
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Offline darkbluenine

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #35 on: 09/16/2013 04:14 AM »
The use of a high altitude nuclear blast would take out a major number of satillites, both civilian and military.  Getting the holes in both the GPS system patched and replacing at least some of the military CNC and surveilance sats would prove critical in this kind of scenerio.

I guess the USAF could have such a doomsday scenario in mind, and DARPA is using it to justify XS-1.  But if the USG was really worried about this, it seems there are simpler, less tech-intensive, more robust ways to have a fallback for rapidly launching a bunch of replacement satellites.  I think reusability is eventually a must in general.  But if I was really worried about a fallback, I'd stockpile and disperse a couple handfuls of Minotaurs and launch crews on warm callup to Kodiak, MARS, and Vandenberg with their attendant satellites before going down an unproven RLV path.

There aren't payloads enough for a highly operational vehicle until the price can be brought down by a highly operational vehicle. The only way to break this paradox is to make a vehicle viable at both ends of the spectrum. IMHO.

Or improve and evolve in small steps instead of trying to bite off everything at once. 

Do you have a vehicle concept in mind, by any chance?

I thought RASCAL was an air-launched rocket concept where they were using some LOX injection in the jet stage's engines to allow a low-subsonic staging velocity...this seems at least to me to be fairly different.

RASCAL was different from XS-1, but it wasn't LOX injection.

RASCAL's key technology was mass injection pre-compressor cooling (MIPPC), i.e., dumping cold water into the intake of a jet engine.  That cools and densifies the air, providing higher thrust at high altitudes.  It can turn a Mach 1+ fighter into a Mach 4+ reusable 1st-stage launcher when teamed with an expendable upper stage.    See sections 2.5 and 3 in this GASL report:

http://ftp.rta.nato.int/public/PubFullText/RTO/EN/RTO-EN-AVT-150/EN-AVT-150-02.pdf

Besides contractor selection, DARPA's mistake in RASCAL was developing an entirely new airframe, instead of just modifying a couple fighters to demonstrate the technology.  MIPCC goes back to 1970s GD work on an F-4 variant capable of flying a heavy recon camera for the Israeli Air Force under Project Peace Jack:

Quote
The F-4X and RF-4X were proposals for advanced F-4E derivatives designed by General Dynamics to carry the HIAC-1 long focal length camera as part of Project Peace Jack. This project was a joint Israel-USAF study for an advanced photo-reconnaissance aircraft capable of Mach 3+ performance.

The HIAC-1 camera was an advanced high-altitude reconnaissance camera that had a focal length of 66 inches which offered unparalled resolution at extreme ranges The HIAC-1 camera was originally so large and heavy that it could only be carried by the Martin/General Dynamics RB-57F. However, later versions were sufficiently slimmed down so that they could potentially be carried by smaller aircraft such as the F-4 Phantom.

Israel had always wanted the HIAC-1 camera for its own use in keeping track of its Arab neighbors, but its requests had always been turned down. However, in 1971, US attitudes towards export of the HIAC-1 camera changed and approval was given for the development of a pod (designated G-139) which could carry this camera on the belly of a Phantom. The prototype G-139 pod was over 22 feet long and weighed over 4000 pounds, and was first tested on an RF-4C in October of 1971.

Unfortunately, the G-139 was still so large and bulky that the performance of the Phantom when it was carrying the pod was unacceptably poor. The Peace Jack project originated in an attempt to improve the performance of the Phantom when carrying this camera. Both the USAF and the government of Israel contributed funds for the project.

Rather than trying to slim down the reconnaissance pod, the original goal of the General Dynamics team was to improve the performance of the Phantom that was carrying it. The improved performance was to be obtained by using water injection for pre-compressor cooling, which would provided increased engine thrust at high altitudes. A similar system had been used successfully in the past in various F-4 record attempts. The water was to be contained in a pair of gigantic 2500-gallon tanks which were to be attached conformally to the intersection joints of the fuselage spine and the engine nacelles. The water injection system promised to give a 150 percent increase in engine thrust at altitude. In order to accommodate the increased engine thrust that would now be available, new air intakes had to be designed. The area of the intakes was to be made much larger and they were to contain a sophisticated system of internal cowls, splitter plates, vortex generators and bleeds. With the new intakes and the water injection system, it was anticipated that maximum speeds of up to Mach 3.2 and cruising speeds of up to Mach 2.7 could be attained. The project came to be known as the F-4X, although this was not an official USAF designation.

Israel was clearly very interested in the F-4X, as it promised a performance which would approach that of the USAF's SR-71. This would enable it to fly unimpeded anywhere it wanted to. However, the advanced performance of the F-4X clearly made it a possible candidate for a new interceptor. Consequently, the US State Department became more than a little worried about the export of such advanced technology overseas, since it promised to give Israel a potential interceptor which was more capable than anything currently in the US arsenal, one which might one day pose a threat to the SR-71. In addition, the Air Force was itself rather nervous about the F-4X project, since it might threaten to divert support away from the F-15 program which was just then getting underway. As a result, the State Department decided to disallow export of this technology to Israel.
 

(Copied from http://www.militaryphotos.net/forums/showthread.php?49454-Several-western-aircraft-concepts-that-were-never-built/page2.)

DARPA should have just finished GD's work using a QF-4 Phantom target drone (I think they can be bought for under $1M nowadays) to prove out the concept instead of trying to design a new MIPCC first-stage from the ground up.  MIPCC is devastatingly simple and effective and fairly proven technology that got fouled by an overly complex execution at DARPA.

It seems to me that grasshopper 2 / 1st stage of F9R could easily fullfil these requirements.

An expendable Falcon 9 stages at Mach 10.  But the reusable version will stage at Mach 6.  See:

http://www.popularmechanics.com/science/space/rockets/elon-musk-on-spacexs-reusable-rocket-plans-6653023

To play in XS-1, SpaceX would probably have to be willing to develop a "stretch" version of the F9R to have enough fuel to hit Mach 10 and get back, at a minimum.  There would probably have to be significant engine and TPS changes or testing to meet the 10-in-10 requirement, too.  It's theoretically possible, but given how much SpaceX already has on its plate, SpaceX dropping out of Stratolaunch, and Musk's focus on Mars, I don't see the company diverting itself for XS-1.

Offline simonbp

Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #36 on: 09/16/2013 05:38 AM »
But the designation XS-1 was already used... ;)

(Bell Aero, not Bell Labs. Different part of Alexander Graham's empire.)

Sounds interesting though; I hope they can actually fund some hardware (unlike RBS).

And no, I don't think involving SpaceX is the point of this. While they'll be welcome to bid, I think the point is to fund other reusable first stages. AFAIK, SpaceX has no critical protected technologies; their advantage is all in experience and infrastructure. A precision injection of DARPA money could allow a cost-competitive alternative to SpaceX that is more willing to build vehicles to USAF's specifications, which is USAF's dream scenario.
« Last Edit: 09/16/2013 05:46 AM by simonbp »

Online ChrisWilson68

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #37 on: 09/16/2013 06:25 AM »
It seems to me that grasshopper 2 / 1st stage of F9R could easily fullfil these requirements.

An expendable Falcon 9 stages at Mach 10.  But the reusable version will stage at Mach 6.

Yes, but the F9R stages at Mach 6 with a full second stage and payload attached.  If it didn't have to carry a second stage and payload, the F9R could certainly hit Mach 10 and then slow down enough to do its usual landing procedure (assuming F9R can land as intended, of course).  The DARPA solicitation is for a vehicle that can hit Mach 10 without an upper stage.  And anyway the payload class the solicitation is talking about is much smaller than the F9R payload, so F9R could probably stage at Mach 10 with the much smaller upper stage that would be needed for that small a payload and still land with no problem.

There would probably have to be significant engine and TPS changes or testing to meet the 10-in-10 requirement, too.

SpaceX certainly designed Falcon 9R not to need significant engine and TPS changes to meet the 10-in-10 requirement.  Elon has been talking about single-digit-hour turnaround times to re-launch the F9R first stage.

Of course, in practice SpaceX might find flaws in their design that mean they can't meet the 10-in-10 requirement.  But so could any other contender for this DARPA proposal.  SpaceX is certainly far ahead of anyone else who might consider trying for the DARPA program.

It's theoretically possible, but given how much SpaceX already has on its plate, SpaceX dropping out of Stratolaunch, and Musk's focus on Mars, I don't see the company diverting itself for XS-1.

That I agree with.  SpaceX probably won't bother to enter the DARPA contest.

But it's certainly worth noting that F9R would meet the DARPA requirements.  I've never heard of another DARPA program whose target is already met by an existing development program for an operational capability.

Having competition for SpaceX might be a good idea, but it's not really DARPA's place to try to pay to get a competitor when an existing commercial program already meets the specs.

Online Robotbeat

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #38 on: 09/16/2013 07:42 AM »
Technically, F9R doesn't have that capability, yet. We hope it will, but we don't know at this point. I've only seen one leg.
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Online ChrisWilson68

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #39 on: 09/16/2013 07:59 AM »
Technically, F9R doesn't have that capability, yet. We hope it will, but we don't know at this point. I've only seen one leg.

Who says you need more than one leg?



Anyway, I agree that SpaceX isn't there yet.  But nobody else is either, and SpaceX has a plan to get there and is trying really hard.  I've never heard of DARPA investing in a project with goals that are a subset of an existing project that is already so far along.


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