GIGANTIC Aviation Week story, Pentagon has been flying 2-stage orbital spaceplane throughout 1990s&# Options

[Guest_BruceMoomaw_*]

It may even have been manned:
http://www.aviationnow.com/avnow/news/chan...ws/030606p1.xml

My God, what a story -- if it's even partially true. And, judging from this article, they are absolutely certain they have proof (along with proof that the thing, although it works, has recently been mothballed as not
cost-effective).

It's important to keep in mind, though, that this thing is NOT a workable prototype of the originally planned 2-stage winged Space Shuttle. The second stage -- the spaceplane that actually achieved orbit -- was relatively small and probably very inefficient as a cargo carrier; its advantage lay in allowing the US to get a military reconaissance (or weapons) satellite into orbit surreptitiously, with no advance warning of the launch going to other countries. Even at that, as I say, AW reports that the thing has been recently canned as not worth its (doubtless huge) black-budget expense.

[Guest_BruceMoomaw_*]

Footnote: the Titan 2 second stage weighed 29,000 kg. I can't find any information on the velocity of the first stage at burnout on a Gemini launch -- but clearly, unless the B-70 was moving at MUCH higher velocity than the Titan first stage and/or the second stage used much more efficient propellant than that in the Titan 2 second stage, there is no conceivable way a 40,000-pound second stage would be adequate to put a Dyna-Soar in orbit.

[tasp]

Footnote: the Titan 2 second stage weighed 29,000 kg. I can't find any information on the velocity of the first stage at burnout on a Gemini launch -- but clearly, unless the B-70 was moving at MUCH higher velocity than the Titan first stage and/or the second stage used much more efficient propellant than that in the Titan 2 second stage, there is no conceivable way a 40,000-pound second stage would be adequate to put a Dyna-Soar in orbit.

Heck, I have no professional reputation to protect, so let me have a go at this intersting wee beastie . . .

Back in the early days of the Atlas program, an entire assembly (less the double annular booster engines) was put in orbit. Seems like an empty Atlas is quite large and weighs 7 or 8000 pounds IIRC. That was nearly an SSTO vehicle back in 1960.

Lets spring forward and pare down the 'bloated Atlas carcass' (no offense to any of it's designers here, rhetorical exercise underway, after all) to something small enough to sling under and XB-70. Lets make it out of carbon fiber material like the recently demised SSTO vehicle. That might get my dry weight down to 2500 pounds or so. My mass fraction with a full fuel load is getting close.

Lets bump up the performance of the XB-70 'six pack' engine module (IIRC, back in the sixties it had a total thrust of <200,000 pounds) to 500,000 pounds since engine performance has improved (not as fast as Moore's law) in the 40+ years since. That will give us maybe Mach 4, 4 1/2, or 5 at 100,000 feet.

We can bump the ISP a tad for a scramjet on the deployed vehicle. Maybe it's an air breathing wave rider of some kind. Let's fuel it with slush hydrogen, with a small tank of lox for the final press to orbit.

Maybe we can make it now!

Think all that would have run 25-30 billion $.

How big is my black budget again?


{thanx, that was fun, I don't think Bruce is making an error backing off the story}

[Bob Shaw]

We can bump the ISP a tad for a scramjet on the deployed vehicle. Maybe it's an air breathing wave rider of some kind. Let's fuel it with slush hydrogen, with a small tank of lox for the final press to orbit.

The AW&ST article speaks of a Boron-based fuel, with a density similar to toothpaste.

That's almost trivial, though. The real problem is obviously handling the Dilithium Crystals!

Where does the undercarriage go?

doesn't "look" right

Nick

Nick:

I agree - imagine an aborted launch, with a fully fuelled bird slung under the mothership. It'd be bad enough with SpaceShipOne, which at least has 'safe' fuel, but landing with a flying fuel tank under the belly of the beast and a fuel you probably don't dare dump within 200 miles of land...

...think how *strong* the landing gear would need to be, too...

Bob Shaw

[Bob Shaw]

One *possible* vehicle which may form part of a somewhat conflated 'new' tale over at AW&ST is the putative X-24C design, not to mention the Lockheed FDL-5A and L-301 air-launched vehicles - all of which are either more-or-less credible depending on who you read - but are certainly not orbital!

Various images below are from: http://www.geocities.com/stratomodels/blackprojects.html or as credited - protype.jpg is slightly retouched, in the best tradition of these matters!

Bob Shaw

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