Author Topic: DARPA Experimental Spaceplane 1 (XS-1) Program  (Read 419590 times)

Offline Danderman

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #140 on: 10/02/2013 05:05 am »

Given that DARPA has sliderules, too, I would suspect either that they know all of this, and are planning something different than has been described here, or else, this is RASCAL Mark II.

Knowing Jess Sponable, I don't think he is planning to execute via concept that won't be affordable/won't fly/won't work. Of course, I knew the RASCAL program manager, and was surprised how that went.

« Last Edit: 10/02/2013 05:13 am by Danderman »

Offline jongoff

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #141 on: 10/02/2013 03:16 pm »
I don't know for sure (we finished our two Phase 1 contracts a few weeks ago), but my guess would be that no they're not open, and the Proposer's Day will more likely get postponed if the gov't stays shut down for long.
Good question. I thought they'd come under Defense, so not discretionary and hence stay open. I guess some bits of the DoD are less critical than others.  :(

Actually, you're right that I don't know for sure if DARPA is part of the shutdown or not. I just sent an email to the address provided for the proposer's day to see if they're delaying. If I get an answer, I'll repost it here.

~Jon

I just heard back from the DARPA XS-1 team, and apparently they're still on for the Proposer's Day next week. Apparently at least for now, they're not part of the government that has been shut down.

~Jon

Offline jongoff

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #142 on: 10/02/2013 03:19 pm »
Given that DARPA has sliderules, too, I would suspect either that they know all of this, and are planning something different than has been described here, or else, this is RASCAL Mark II.

Yeah, I really don't think this is an attempt to do RASCAL Mk2. The info they've posted to-date make XS-1 and RASCAL sound like they had only a tiny bit in common. But until we get more details during the industry day, we're all giving our own spin and interpretation on like 2pgs of info.

Quote
Knowing Jess Sponable, I don't think he is planning to execute via concept that won't be affordable/won't fly/won't work. Of course, I knew the RASCAL program manager, and was surprised how that went.

Sometimes when a DARPA program manager sells a program to the office leadership, they have to make compromises to get the money. But that said, I agree wholeheartedly that I don't think Jess would be even trying to startup a program that he didn't feel had a realistic shot of flying within a budget that he was confident he could get from DARPA. So, I agree that any interpretation of the requirements that implies "this would only fly if they had $1B for the program" is probably a misinterpretation. Jess ain't stupid.

~Jon

Offline john smith 19

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #143 on: 10/02/2013 08:46 pm »
I just heard back from the DARPA XS-1 team, and apparently they're still on for the Proposer's Day next week. Apparently at least for now, they're not part of the government that has been shut down.
Excellent news.

Sometimes when a DARPA program manager sells a program to the office leadership, they have to make compromises to get the money. But that said, I agree wholeheartedly that I don't think Jess would be even trying to startup a program that he didn't feel had a realistic shot of flying within a budget that he was confident he could get from DARPA. So, I agree that any interpretation of the requirements that implies "this would only fly if they had $1B for the program" is probably a misinterpretation. Jess ain't stupid.
Sounds right. If RASCAL was unfeasible with a payload to orbit of something like 10s of Kg making it work for less money and a payload of 450-2000Kg (before you add the upper stage mass) is just absurd.  :(

On a practical note I think one area that will make this tough is the very limited range of engine sizes available for it to be implemented.  The obsession with the one big engine per stage gives you a stage of that size (or thereabouts) or a huge multi engine stage.

It would seem for something like this some kind of LOX/HC (I'd prefer Propyne, but otherwise any HC would do) engine in the 100 000 lb with decent stress margins would be a good ideal, but that's not available. 

For engines that have been designed into reusable applications that gives the RL10, Merlin D and Merlin D Vac and the AJ26.  Any other candidates would welcome.  :(
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Offline simonbp

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #144 on: 10/02/2013 10:18 pm »
RL-10 might be interesting. The original Shuttle Phase A was designed around have one common LH2 engine (SSME) with 10-ish SSMEs on the first stage and 2 or 3 SSMEs on the second stage. A miniature version of this with an array of DC-X style RL-10s on the first stage could work fine.

Offline Oli

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #145 on: 10/03/2013 08:05 am »
^

The RL10A-5 used in the DC-X had quite pathetic thrust (64.7kn) and ISP (373), admittedly with a 4:1 exp. ratio.

Offline john smith 19

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #146 on: 10/03/2013 12:27 pm »
The RL10A-5 used in the DC-X had quite pathetic thrust (64.7kn) and ISP (373), admittedly with a 4:1 exp. ratio.
Perhaps. But they got the job done, which is what counts.

Obviously you'd need quite a few of them to lift the upper stage to M10. 1 RL10 is about 7 Merlin D's thrust wise but 1 RL10 is about 14 Merlin's cost wise?

I think people's approaches will depend on what they have on hand or can acquire for this mission
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Offline jongoff

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #147 on: 10/03/2013 10:55 pm »
Jeff Foust is reporting that DARPA changed its mind and will now be postponing the Proposer's Day next week, due to the gov't shutdown. Which is a bummer. Once things are up again, I'm sure they'll post a new date.

~Jon

Offline darkbluenine

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #148 on: 10/04/2013 04:56 am »
Jeff Foust is reporting that DARPA changed its mind and will now be postponing the Proposer's Day next week, due to the gov't shutdown. Which is a bummer. Once things are up again, I'm sure they'll post a new date.

A new date will hopefully de-conflict my schedule.  Depending on what the new date is, I'll try to attend and report back here.  As we get closer, if folks have topics they want notes on, post here or shoot me a PM.

Offline john smith 19

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #149 on: 10/04/2013 10:25 am »
A new date will hopefully de-conflict my schedule.  Depending on what the new date is, I'll try to attend and report back here.  As we get closer, if folks have topics they want notes on, post here or shoot me a PM.
That would be very helpful. I'd be surprised if the day didn't answer pretty much all the questions the forum has thrown up, either directly or possibly by not forbidding certain options.

I guess the other question is what happens if the debt ceiling negotiations get into trouble and everything gets frozen.  I don't think that has ever happened (most of what I know about USG funding is watching the NASA budget) but I'm guessing anything like this (all of DARPA?) gets put into the deep freeze and the USG switches to "safe mode." :(  :(

I really hope the Legislature can work out a compromise before that happens.

Returning to topic I suggested the AJ26, RL10 and Merlin 1D as active engine programmes that could have a stage built round them and have either been used in or planned for use in reusable vehicles.

It did occur to me that the SSME should technically be on the list due to the disposable version for the SLS, but I think all the current ones are earmarked for launches and I've no idea what stage the expendable version is at (RS25D or E?)

Can anyone suggest any others? 
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline a_langwich

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #150 on: 10/04/2013 12:51 pm »

Returning to topic I suggested the AJ26, RL10 and Merlin 1D as active engine programmes that could have a stage built round them and have either been used in or planned for use in reusable vehicles.

It did occur to me that the SSME should technically be on the list due to the disposable version for the SLS, but I think all the current ones are earmarked for launches and I've no idea what stage the expendable version is at (RS25D or E?)

Can anyone suggest any others? 

I'm still curious what engine Lockheed Martin test-fired 15x as part of the RBS Pathfinder program at their Colorado R&D location.  Skunk Works is in California?  Didn't think they wanted to be in the engine business.  Maybe it wasn't a first stage engine?  Or are they working on in-house propulsion, perhaps in conjunction with XCOR's piston pump guys, perhaps with an eye toward more vertical integration to compete on pricing?  Probably just a red herring.  But RBS wanted AFAIK an ORSC kerolox first stage and hydrolox second, and the ORSC engine was viewed by the NRC as one of the program risks (so it would make sense to tackle the long pole in the tent first, right?).

Offline darkbluenine

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #151 on: 10/04/2013 02:21 pm »
Returning to topic I suggested the AJ26, RL10 and Merlin 1D as active engine programmes that could have a stage built round them and have either been used in or planned for use in reusable vehicles.

It did occur to me that the SSME should technically be on the list due to the disposable version for the SLS, but I think all the current ones are earmarked for launches and I've no idea what stage the expendable version is at (RS25D or E?)

Can anyone suggest any others?

The cupboard really is bare, especially in hydrocarbon, which is probably what XS-1 will require.  I wouldn't be surprised if Phase 1 involves subsystem work, including bringing a new engine or two forward.

I scraped together a few other engines that don't meet your active program criterion, but they come close:

CHASE-10 --  LOX/CH4.  22Klb thrust.  Est. 10K sec of reusability.  180 test firings to date.  Heavy engine with low Isp, but that may not matter much in the XS-1 first-stage application, especially given the high reusability that the engine offers.  Developed in South Korea by ex-Hyundai engineers.  They established a firm in Denver called DARMA Technology to offer it in the US:

http://www.darmatechnology.com/chase-10-methane-rocket-engine.html

BE-3 --  LOX/LH2.  100Klb thrust.  Presumably highly reusable.  At least 1 test firing at Stennis earlier this year.  Developed by Blue Origin under commercial crew.  I'm skeptical of big LH2 engines in these highly reliable military applications given RS-25 experience, but maybe Blue has figured out something Rocketdyne hasn't:

http://rocketry.wordpress.com/2013/03/06/blue-origin-tests-its-be-3-engine/

RL-60 --  LOX/LH2.  60Klb thrust.  At least restartable.  Test-fired back in 2003 but shelved afterward.  Replacement for RL-10; same displacement with twice the thrust and some fraction of the cost:

http://www.aero-news.net/index.cfm?do=main.textpost&id=4ddce23e-0de1-4d1f-bd76-3d78da86c0ba

Raptor -- LOX/CH4 upper stage or family.  AFAIK, SpaceX has not released/leaked any other details.

Here's a brief comparison of some of these engines in terms of upper stage applications:

http://depletedcranium.com/we-need-a-new-cheaper-upper-stage-engine/

It will have a lower TRL, but I wonder if DARPA has some old pulse detonation engine technology from Blackswift that they might also try to leverage for XS-1?
« Last Edit: 10/04/2013 02:26 pm by darkbluenine »

Offline baldusi

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #152 on: 10/04/2013 05:40 pm »
BE-3 is a 445kN (100klbf) tap off cycle. I.e. they tap some of the combustion chamber gas and use it to run the turbopump. I understand that requires an open cycle. It's very interesting because it doesn't have a gas generator but it doesn't have the scaling problems of the expander cycle. On the other hand, it's probably not very good at isp, since you can only get to something like 900K in the turbine blades. And the Japanese have shown open cycle expander to 1.5MN. I'm guessing, thus, that it won't be run close to stoichiometric.
The Raptor is known to be a staged combustion and around 3MN (they stated 650klbf). Quite a bit big than any other engine you mentioned. For first stage reusability, CH4 sort of rules, given the coking-free nature of the fuel, easiness of a fuel rich combustion cycle, it's isp (around 10s above similar RP-1) and the relative density (only 30% more than RP-1, compared to 200% of H2). I still think that they secret for the sort of development that DARPA wants would be a cycle that uses oxidizer in our atmosphere as much as possible. And in that case a fuel that uses a huge amount of oxidizer is preferred, hence, the Skylon.
« Last Edit: 10/04/2013 05:47 pm by baldusi »

Offline simonbp

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #153 on: 10/04/2013 06:08 pm »
Yes, DARMA engine could be dark horse. They actually brought a full engine to Space Access a few years ago, it was quite solidly built; it reminded me of the V-2's engine.

Offline jongoff

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #154 on: 10/04/2013 07:45 pm »
Yes, DARMA engine could be dark horse. They actually brought a full engine to Space Access a few years ago, it was quite solidly built; it reminded me of the V-2's engine.

Which reminds me--the DARMA guys are now just about 15min down the road, and I still haven't made it over to visit them yet this year.

~Jon

Offline john smith 19

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #155 on: 10/04/2013 08:42 pm »
I'm still curious what engine Lockheed Martin test-fired 15x as part of the RBS Pathfinder program at their Colorado R&D location.  Skunk Works is in California?  Didn't think they wanted to be in the engine business.  Maybe it wasn't a first stage engine?  Or are they working on in-house propulsion, perhaps in conjunction with XCOR's piston pump guys, perhaps with an eye toward more vertical integration to compete on pricing?  Probably just a red herring.  But RBS wanted AFAIK an ORSC kerolox first stage and hydrolox second, and the ORSC engine was viewed by the NRC as one of the program risks (so it would make sense to tackle the long pole in the tent first, right?).
Good question. My instinct is that an ORSC engine would swallow the whole XS-1 budget and still not give a result.  :( LM did a joint project with Xcor on a new RL10 replacement engine, but that seems to have gone very quiet.

The engine for the RBS pathfinder is (presumably) in better shape, but that does not necessarily mean it's flight weight.
The cupboard really is bare, especially in hydrocarbon, which is probably what XS-1 will require.  I wouldn't be surprised if Phase 1 involves subsystem work, including bringing a new engine or two forward.
I can understand the field is limited but I think this would side track the project.
Quote
I scraped together a few other engines that don't meet your active program criterion, but they come close:
Given the size of the field I'm prepared to stretch a point  :)
Quote
CHASE-10 --  LOX/CH4.  22Klb thrust.  Est. 10K sec of reusability.  180 test firings to date.  Heavy engine with low Isp, but that may not matter much in the XS-1 first-stage application, especially given the high reusability that the engine offers.  Developed in South Korea by ex-Hyundai engineers.  They established a firm in Denver called DARMA Technology to offer it in the US:

http://www.darmatechnology.com/chase-10-methane-rocket-engine.html
Essentially a Methane/Lox RL10 equivalent, but (presumably) a lot cheaper. In this application I think reliability trumps absolute performance. Adequate beats maximum performance IMHO.
Quote
BE-3 --  LOX/LH2.  100Klb thrust.  Presumably highly reusable.  At least 1 test firing at Stennis earlier this year.  Developed by Blue Origin under commercial crew.  I'm skeptical of big LH2 engines in these highly reliable military applications given RS-25 experience, but maybe Blue has figured out something Rocketdyne hasn't:

http://rocketry.wordpress.com/2013/03/06/blue-origin-tests-its-be-3-engine/
Fair point. But SSME taught a lot of lessons and NASA did a lot of development work to improve the SSME. If BO did their background research (and I've no reason to doubt their competence) they will have incorporated lessons in bearing and seal technology, possibly going to actively cooled turbine blades, although that's more speculative. I'd guess not going with staged combustion would also help the reliability, while using the Aerojet premixed catalytic ignitor tech could make ignition as simple as opening a pair of valves, and as reliable as hypergolics. [edit An overlooked aspect of SSME was to save weight they used a lot of "fabricated" parts IE thin(ish) sheets welded together.  Later versions went to high quality castings but took a weight hit. Today CNC press tools could make them relatively cheaply, or diffusion bonding or friction stir welding (neither of which melt the metal) could give much higher quality joins. Note SSME was built entirely without CAD tools, making setting up CFD models much harder as well.]

Of course it is still an LH2 engine with the LH2 handling issues. But it's a nice "building block" size.  :)
Quote
RL-60 --  LOX/LH2.  60Klb thrust.  At least restartable.  Test-fired back in 2003 but shelved afterward.  Replacement for RL-10; same displacement with twice the thrust and some fraction of the cost:

http://www.aero-news.net/index.cfm?do=main.textpost&id=4ddce23e-0de1-4d1f-bd76-3d78da86c0ba
Did they get to build a complete engine? I though they only got as far as a combustion chamber/injector test.
Quote
Raptor -- LOX/CH4 upper stage or family.  AFAIK, SpaceX has not released/leaked any other details.
Spacex have a lot on and the only way I can see this happening is if they decide to enter the contest directly.
Quote
It will have a lower TRL, but I wonder if DARPA has some old pulse detonation engine technology from Blackswift that they might also try to leverage for XS-1?
Possible. I guess it would depend if you want to go with air breathing as an option and its T/W ratio relative to existing rockets.

BTW I just remembered the Orbitec "vortex cooled" pressure fed might also be a candidate.

I think a lot of things will depend on wheather DARPA already has an upper stage in mind or if that's open as well.
BE-3 is a 445kN (100klbf) tap off cycle. I.e. they tap some of the combustion chamber gas and use it to run the turbopump. I understand that requires an open cycle. It's very interesting because it doesn't have a gas generator but it doesn't have the scaling problems of the expander cycle. On the other hand, it's probably not very good at isp, since you can only get to something like 900K in the turbine blades. And the Japanese have shown open cycle expander to 1.5MN. I'm guessing, thus, that it won't be run close to stoichiometric.
The Raptor is known to be a staged combustion and around 3MN (they stated 650klbf). Quite a bit big than any other engine you mentioned. For first stage reusability, CH4 sort of rules, given the coking-free nature of the fuel, easiness of a fuel rich combustion cycle, it's isp (around 10s above similar RP-1) and the relative density (only 30% more than RP-1, compared to 200% of H2). I still think that they secret for the sort of development that DARPA wants would be a cycle that uses oxidizer in our atmosphere as much as possible. And in that case a fuel that uses a huge amount of oxidizer is preferred, hence, the Skylon.
If that's correct this is a serious piece of cutting edge technology. No one has done a gas tapoff since the original J-2S/S in the late 1960's. BTW the J-2S design improved on the J-2 Isp by 5-10secs IIRC and cut the weight by eliminating the gas generator. 

BTW the J-2S replaced a rather complex (Unique?) GH2 spin up system with a 5 round cartridge starter. However by the time the project was cancelled they'd cracked how to reduce the the back pressure, so internal tank pressure was good enough to spin up the turbine, eliminating the starter cartridges.  They were also working out how to reduce flow separation, presumably to allow the use of the high expansion ratio nozzle at sea level.

[edit. And that description of Raptor is huge for a 2nd stage engine. 2 of these would supply the whole F9 takeoff thrust, needing a much bigger 1st stage to justify it.]
« Last Edit: 10/05/2013 01:57 pm by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline darkbluenine

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #156 on: 10/05/2013 02:11 am »
Which reminds me--the DARMA guys are now just about 15min down the road, and I still haven't made it over to visit them yet this year.

Get over there and tell them they need to show up for the XS-1 proposer's day if they're not already planning to do so and to reach out to the potential vehicle builders and primes.  It's probably the best shot they have of getting that engine into a vehicle.

Offline john smith 19

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #157 on: 10/06/2013 03:03 pm »
Get over there and tell them they need to show up for the XS-1 proposer's day if they're not already planning to do so and to reach out to the potential vehicle builders and primes.  It's probably the best shot they have of getting that engine into a vehicle.
Definitely  :)

Getting their name and face out there amongst the vehicle builders. I think a key with such a company is that have to able to handle any ITAR issues. If they have this in hand no problem.

While such an engine is likely to need quite a lot of clustering it's Isp should be quite good and it's T/W better than a LO2/LH2 design.

It's propellants should also be quite cheap, which is going to be important for operating costs.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline darkbluenine

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #158 on: 10/07/2013 09:35 pm »
There's a summary article on the XS-1 announcement(s) at the Space Review:

http://www.thespacereview.com/article/2379/1

A couple details are new (at least to me).

One, Sponable is quoted as saying:

Quote
"How it’s configured, how it gets up, and how it gets back are pretty much all on the table—we’re looking for the most creative yet practical solutions possible."

Going back to a point I raised earlier in the thread, it doesn't sound like XS-1 will have an RTLS requirement.  If true, that opens up a lot of solution space.  It may be easier/less expensive to build a second landing/launch site on some island off Africa (or wherever) and turn XS-1 around and launch back due west after an eastward launch than incorporate an RTLS capability, especially when DDT&E costs and payload mass penalties are incorporated.  Also seems synergistic with non-launch applications for the military.

Also going back a point raised by a couple folks earlier in the thread, Sponable's apparent open-mind towards propulsion and configuration may also open up solution space.  I agree with earlier comments that the only way to hit Mach 10 within a DARPA budget is via rockets and not advanced air-breathing propulsion (ramjet/scramjet-type stuff).  But the emphasis on practicality regardless of configuration or propulsion makes me wonder if there isn't a solution here that adds some complexity with jet engines, augmented or not, to reduce the work of the rocket engines and thus their size and/or number and resulting costs.  Arguably, if you want aircraft-like operations, use as many proven aircraft components as reasonable.

Second, we also get a sense of schedule and programmatic content from the article:

Quote
After phase 1, Sponable said DARPA will examine the cost estimates those companies will provide to develop XS-1 before making a decision on phase 2, with a goal of flight tests in 2017 or 2018."

It sounds like Phase 1 is a design cycle, although I wonder if they’ll push an technologies before Phase 2.

Third, the article makes clear that DARPA wants this capability to reside in industry as a service.  The resulting capability is not a military or government vehicle:

Quote
At the STA meeting, Sponable emphasized that while XS-1 was being funded by DARPA, it was not the agency’s goal to develop a vehicle for the government. DARPA director Arati Prabhakar, he said, "wants to make sure we transition this to industry, not to the United States Air Force and not to NASA." Those agencies, he said, can instead purchase launch services using the XS-1 vehicle from the company that develops it.

That sounds promising to me from a launch point-of-view.  Will help minimize requirements from non-launch applications and maximize practicality/low-cost.  It sounds like Sponable's management chain shares his convictions.

FWIW...

Offline john smith 19

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #159 on: 10/08/2013 11:02 am »
There's a summary article on the XS-1 announcement(s) at the Space Review:

http://www.thespacereview.com/article/2379/1

A couple details are new (at least to me).

One, Sponable is quoted as saying:

Quote
"How it’s configured, how it gets up, and how it gets back are pretty much all on the table—we’re looking for the most creative yet practical solutions possible."

Going back to a point I raised earlier in the thread, it doesn't sound like XS-1 will have an RTLS requirement.  If true, that opens up a lot of solution space.  It may be easier/less expensive to build a second landing/launch site on some island off Africa (or wherever) and turn XS-1 around and launch back due west after an eastward launch than incorporate an RTLS capability, especially when DDT&E costs and payload mass penalties are incorporated.  Also seems synergistic with non-launch applications for the military.

Second, we also get a sense of schedule and programmatic content from the article:

It sounds like Phase 1 is a design cycle, although I wonder if they’ll push an technologies before Phase 2.

Third, the article makes clear that DARPA wants this capability to reside in industry as a service.  The resulting capability is not a military or government vehicle:

That sounds promising to me from a launch point-of-view.  Will help minimize requirements from non-launch applications and maximize practicality/low-cost.  It sounds like Sponable's management chain shares his convictions.
It sounds like they are making all the right moves. A very pragmatic approach. :)

They seem to aim at making things as inclusive (both in terms of design options and potential customers) as possible. Given how tough this mission is I think ruling out virtually anything (or any user group) is a bad idea.

Realistically it will be rocket based, with possibly some simple (ish) refinements [edit RENE adds 50% thrust on base rocket with fixed geometry and about 3x the mass flow of the base engine in the M0-M2 range.that's (potentially) a good payoff just when you're vehicle is at it's heaviest] , but there is just the outside chance someone has something sitting in their warehouse that can get the job done.

[edit I'm thinking a decent sized set of PDE's, but I'm clueless on their T/W. I've heard claims of ramjet T/W of 12:1. So PDE's are better? Worse? Unfortunately that probably gets you back to the M10 aircraft design problem, and the need for some very creative solutions. Some kind of "enhanced" supersonic biz jet construction, cruising at M1.5 at 10% throttle before a zoom climb as the throttles go to 100% for a few seconds at M10? If it gets the job done...]

I like the attitude that "If it gets the job done at the price, it's good enough." So even the "ping pong"between 2 launch pads architecture is a possible candidate. It does sound like both Sponable and his management chain are in agreement on this.

I just hope that this programme does not fall prey to whatever deal is finally worked out to resolve the shutdown. It should be small enough to be under the budgetary radar, but who knows? :(
« Last Edit: 10/08/2013 11:44 am by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

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