The Douglas ASTRO: An Air Force Launcher

douglas-astro

The ASTRO, as pictured in the September 3, 1962 issue of Missiles and Rockets. Image artist unknown and copyright status uncertain, but believed to be in the public domain. Via the Internet Archive.

What it was: A lifting body craft proposed to the USAF by Douglas Aircraft. It would initially be used as a suborbital trainer then, after up-scaling and being paired with a second lifting body in an unusual nose-to-tail arrangement, evolve into a fully reusable vehicle with a nine-tonne payload capacity to LEO.

Details: In late 1962, the USAF was on the cusp of deciding how it would go forward with its plans to put military men in space. The X-15 had made its first flight mid-year, and the X-20 program was ramping up. Doubts about the latter were getting stronger, though, and would ultimately result in the Air Force deciding to work on the Manned Orbiting Laboratory instead.

It was at this point that an article was published in the now-defunct Missiles and Rockets magazine outlining a proposal from Douglas Aircraft that was supposedly being evaluated by the USAF. What it outlined was a two-part development program that would check the usual laundry list of military applications for space as perceived in the early 1960s.

The core of the ASTRO (Advanced Spacecraft Truck/Trainer/Transport Reusable Orbiter) was the answer to a question the USAF had proposed to North American Aviation and Douglas, as well as Boeing, Vought, and Republic: how to train pilots for the X-20 on actual flights prior to the X-20 being built. North American had come back with what they called the STX-15, which was a way of reconfiguring an X-15 to have the projected flight characteristics of an X-20 (except for, of course, the highest speed and orbital parts). The Phase I of Douglas’ ASTRO was their significantly more ambitious counter to the NAA proposal.

astro-schematic

A schematic of the ASTRO’s A2 vehicle, which would be both independent for suborbital hops, or be boosted to the point that it could be lifted into orbit by a derivative of the same vehicle. Note the booster nose’s ghostly presence at the far right of the image. Same source as previous. Click for a larger view.

Unfettered by the previously existing X-15, Douglas wanted to build a completely new craft dubbed A2, which would be capable of suborbital hops of about 5000 miles (8000 kilometers) after taking off from a runway under the impetus of a J-2 engine, the same rocket engine used by the Saturn V’s second and third stages. Pilots would get their space training, the USAF would have themselves a reusable vehicle with intercontinental range which could carry ten people, or a similar amount of payload. Two RL-10s, as used on the Centaur, would provide a little extra oomph.

Phase II was where Douglas diverged from the question being asked. Take the A2, modify it so that it only carried one crew and two extra J-2 engines, then stick it nose to bumper on the end of another A2 built to the Phase I spec. Turn it 90 degrees and launch it vertically, with the two separating from each other at altitude and speed (both unspecified). The sole crew member aboard the booster would glide back to Earth, while the uppermost A2 would ignite its engines, hopefully after allowing a bit of distance to build from the booster, and carry on into orbit. Douglas projected two crew and about a tonne of cargo to LEO in this configuration.

Phase III scaled up the booster, now dubbed B, and equipped it with two J-2s and one M-1, a never-built LH2/LOX engine that dwarfed even the F-1 engines used on the Saturn V’s main stage. Also launched vertically, this would be the ultimate version of the craft.

The full, two-stage Phase III vehicle was to have been 159 feet long (48.5 meters) and while mass was not mentioned the propellant capacity of the stages (165,000 pounds for the A2 and 594,000 pounds for the B) are—this suggests a total loaded vehicle mass at launch of about 380 to 400 tonnes. Total payload, as mentioned previously, was about nine tonnes, including crew, and there’s a sign that Douglas was nervous about this: the article specifically mentions wanting to launch due east from the Equator, which is an odd thing to be suggesting in 1962, well after the US had committed to launching from the continental USA.

If built, the program was expected to run from 1964 to 1970, with the first flight of the Phase III craft at the end of that period.

What happened to make it fail: It’s difficult to fit the ASTRO into the chronology of the X-20. Phase I appears to have been an attempt to come up with a “Gemini” for the X-20’s “Apollo”, giving the USAF the capability of sending pilots on long suborbital jaunts to train them for the environment they’d encounter when aboard the fully orbital X-20. Phase III would then have been a follow-up to the X-20, increasing crew capacity and payload over that craft.

If this is the case, then, it explains why the ASTRO never went anywhere. The craft made its sole notable public appearance in September of 1962, and American Secretary of Defense Robert McNamara was definitely thinking about cancelling the X-20 no later than March 1963—and possibly earlier. When the X-20 was stopped, then ASTRO would go with it. This is particularly true if one assumes, as seems likely, that the USAF was never very warm about the idea at all, and that it primarily existed as a pitch from Douglas leaked through Missiles and Rockets magazine to drum up support. There’s essentially no reports or discussion of ASTRO post-dating the magazine’s unveil.

What was necessary for it to succeed: It’s not easy to see a way forward for this one. X-20 was dead in the water less than six months later (eventually being formally cancelled in December 1963), and the payload capacity of even the Phase III ASTRO was marginal for what would have been an expensive program. There’s also the issue of Douglas vastly exceeding the question posed by the USAF—it’s unclear that there was any interest on the part of the Air Force in anything other than Phase I. This in turn defeated the purpose of building a fully operational craft for pilot training.

Sources

“Air Force Studies Space Trainer”, Missile and Rockets. September 3, 1962.

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6 thoughts on “The Douglas ASTRO: An Air Force Launcher

  1. Being engaged with several “Alternate History” approaches to developing reusable or semi-reusable orbital launch systems, projected into the past at various eras (alternate STS decisions, post-Challenger repurposing of STS hardware, and yet other possible divergences) what I gather from the lore is that what scuppered VentureStar, the yet more ambitions SSTO scheme supposedly on the drawing board to replace the Shuttle, was the troublesome matter of trying to configure liquid hydrogen tanks in odd, non-cylindrical shapes with sharp corners. I can see from the diagram that ASTRO designers blithely assumed they could tuck liquid hydrogen tanks in odd shapes stuffed into the flat delta wing. To be sure it is quite a thick delta wing, but even if ASTRO had been disentangled from X-20 and evaluated in its own right, and some patron had taken it up–if not the USAF then NASA as an advanced project (highly unlikely with Apollo moonshot tech taking up all the resources at the time) I would think the problem of hydrogen tankage alone would prove fatal sooner than it even did for VentureStar.

    I daresay there is more to the VentureStar story than just frustration with the tanks; it certainly occurs to me that one solution is to design the lifting body shape (more or less “deltoid pumpkin seed”) around a fairly cylindrical central hydrogen tank, putting the less challenging LOX in the “wingtips.” Of course, the difficulty of odd-shaped cryogenic tanks might be as bad, or nearly so, with LOX than LH2 despite its much higher temperature and density. As I say other difficulties may have loomed large with the frustrating failures of solutions for the tanks being merely the excuse chosen to terminate it. SSTO is inherently difficult because every ounce of overweight comes straight out of the payload, no matter what the detailed approach.

    Another problem with reusable stages that contain LH2 in particular but in principle any propellant is that the apparently simple if somewhat massy notion of just making a normal cylindrical tank and then enclosing it in an outer hull with aerodynamic load bearing structure and thermal protection systems is that propellants, hydrogen especially, will leak. When as with STS’s external fuel tank or even a Saturn rocket’s tankage integral with the stage structure, hydrogen does leak, it poses a serious hazard, but one that is rapidly diluted by the air and that has a dynamic tendency, despite low temperatures, to rise when it is not diluted (to an extent diluted hydrogen in air does also cause that air to be lighter and thus rise also–but mixed like that is when it is hazardous!) so it mixes fast. The hazard is real but mitigated. Not so if the inner tank is enclosed closely in an outer hull! Then the hydrogen can rise to dangerous concentrations over dangerously large volumes.

    And locating and plugging leaks is obviously far more difficult; the only practical ways I could see would be either to provide very large clearances between inner tank and outer hull for some kind of periscopic equipment or repair droids to snake or crawl in there, or to access the tank from within. The former involves mass-raising bulk and is still very tricky, the latter works well only if one has evacuated the tank and put air in it.

    This all might be doable on a big rocket, something like a new edition of VentureStar or some Saturn V stage derived thing. On a mini space fighter sort of vehicle like this I’d say it is practically impossible.

    Even given mid 2010’s contemporary tech, I don’t think we could do it today. I sure don’t think anyone, not even Douglas, could do it in the 1960s.

  2. This would have been a fantastic jump in our technology. At least Virgin galactic is remaking this in another way. It amazes many who never studied the past on haow many things are really old ideas redressed.

  3. Hi Paul, I guess you haven’t seen British Secret Projects 5: Britain’s Space Shuttle from Crecy. It’s got a whole chapter on ASTRO, based on two original Douglas reports…
    Dan

  4. “a reusable vehicle with intercontinental range which could carry ten people” – they should have sold it to the Army or USMC, as that’s pretty much what SUSTAIN was planned to do in 2002!

    (I did an analysis of Ithacus and SUSTAIN on my blog a little while back – the post should be linked from “RogerBW” above.)

    • Ah, one of Philip Bono’s! You may have noticed a lack of any False Steps about him and Krafft Ehricke. They both churned out so many proposals with not one getting a sniff of official approval that I’ve shied away from both of them. It almost seems like cheating.

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