Spaceplanes investigated only by DARPA. Good or bad?

[spacefire]

Do you think NASA completely abandoning spaceplanes with DARPA picking up the pace is a good thing?<br />DARPA has done some interesting stuff in the past, which benefitted civilians as well- the Internet, duh- but does it have the resources to develop an experimental manned spaceplane, and will it ever release the results of their research? <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[mlorrey]

The RASCAL reference vehicle design has some serious flaws: up to 250 miles of circular range to reach 'launch window' and 30 minute loiter time when there, this all costs serious quantities of fuel for the 1st stage which IMHO is a waste: if your systems don't check out on take-off when you need your launch window, the mission should be scrubbed til the next launch window. RASCAL also focused too much on F-100 engines with MIPCC. Those turbofan engines are heavy, terrible T/W compared to newer engines that are well proven. They also ruin the mass fraction, even while the vehicle carries minimal fuel.<br /><br />They didn't pick up the RBCC engines that NASA developed because they were 'further out'. IMHO Thiokol ATK is running things through Cheney and Rummy.<br /><br />A tow launch with light weight ramjets is a much smarter idea. Ramjets have a 50:1 T/W ratio, vs 10:1 for the best turbofans. Use either RP-1. MAPP, or propargyl alcohol as fuel (with or without boron). PA is C3H40, a molecule that is fantastically dense (.944 g/cc) with hydrogen and a low carbon count.

 

[john_316]

They recently tested that hypersonic cruise missile deal off of Wallops with JP-10 fuel so we'll see where that leads. <br /><br />Perhaps beyond just cruise missiles...<br /><br />I still think a X-34/X40 derived vehicle can do what SS1 did for Rutan. I think the spaceplane derived there can be launched off a modified 747 and do manuevers like the SAGGER bomber deal. <br /><br />SS1 weighted in less than 8000lbs so I imagine a 16000 to 20000lb version could be built and carried aloft on a 747 and launched faster than Mach 15+ for an low orbital flight that could in theory deliver 2 1000 precision guided bombs or other weapons to a pin point accuracy but is that really needed. Probably Not!<br /><br />But<br /><br />A 20,000lb pound aero-spacevehicle that can launch anywhere with say a 12 to 24 Special Forces manned rocket capsule aka "drop ship" like the Marines originally wanted and you can send some troops behind enemy lines faster than transporting them on a C-17 or C-5....<br /><br />Just thinkin on that one...<br /><br /><img src="/images/icons/smile.gif" /><br /><br />

 

[CalliArcale]

DARPA has a mixed history. They do some very exciting and cutting-edge things that nobody else bothers to try, but the funding is notoriously fickle and they're often one of the first on the chopping block if the government is having trouble balancing the books. Will they produce a successful spaceplane? Probably not; they usually fund development of technologies, not finished products, and they generally do it with an eye to enabling a company to develop something that they otherwise could not afford to do -- advancing the state of the art, not building new widgets. So I doubt DARPA will be carrying passengers to Mars, but if all goes well, they may yet enable a company to someday carry passengers to Mars. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[mlorrey]

One thing to keep in mind: x-vehicles are NOT operational vehicles. The X-43A is a good example: it was filled with computers and sensors that are totally unncessary in an operational vehicle. It was essentially a flying wind tunnel. Its LH2 fuel tank was a tiny fraction of its volume. No attempt was made at attaining a mass fraction capable of reaching orbit or any speed higher than the experiment speeds. <br /><br />Similarly, the DC-X was not intended as an operational vehicle, it was only intended to test T/O and landing techniques and ground operations streamlining. The DC-Y would have tested the full flight envelope to orbit, but STILL would not have been built to carry cargo, that was the job of DC-I, the third model.<br /><br />The DARPA Scram-missile also is not intended as an operational vehicle, but its technology could be transferred to one.<br /><br />DARPA programs are generally operated as R&D welfare for the defense industry, much as NIH/CDC research is welfare for the drug industry, NOT to produce commercially viable products in and of themselves, just the technologies that could be used in such products.<br /><br />The current launcher builders have successfully turned the market into an oligopoly. The only way to break this failed market is for a billionaire to put it all into breaking the oligopoly, breaking through with the new technologies, and not being scared off by vaporware from the existing contractors. Branson/Allen have done this in a small scale. Branson may succeed in the medium scale.

 

[danwoodard]

>> they usually fund development of technologies, not finished products, and they generally do it with an eye to enabling a company to develop something that they otherwise could not afford to do -- advancing the state of the art, not building new widgets.<br /><br />Hey - that's what NASA used to do, back in the 50's. Provide funding for the risky projects that industry can't do by itself, to advance aerospace technology and keep the US civil aerospace industry competitive with the world. Technology development! What a concept! It might keep the US from getting left in the dust! <br /><br />In fact, according to the National Aeronautics and Space Act, NASA is supposed to do this for all areas of aviation and space except those that are primarily military. Unfortunately this particular mission seems to have been assigned a rather low priority.