Immediately after WWII, the American aeronautical industry became interested in applying nuclear power to anything that could fly. In 1947, North American Aviation published a groundbreaking report on the use of atomic power in rockets and ramjets, concluding that both were possible. They designed the clear and obvious predecessors to both NERVA and Project Pluto. The NAA D44-100 nuclear ramjet vehicle was, like Pluto, a two stage intercontinental cruise missile, with the first stage being a rocket booster to get the nuclear ramjet up to speed. Unlike Pluto, the nuclear ramjet was an axially symmetric design with the payload (a single nuclear weapon) kept within the long inlet spike.
This, along with a nuclear rocket ICBM that clearly used V-2 aerodynamics, were the first serious engineering design studies of nuclear powered vehicles of which I’m aware. After more than sixty years, there’s nothing about the designs that screams “wrong.” Just a few aspect that scream “obsolete.” And, of course, some that scream “Ha Ha! Your civilization never got around to building anything nearly as cool as this!!!”
See more on these by checking out issue V2N2 of Aerospace Projects Review.
8 Responses to “Nuclear Ramjet, 1947”
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It looks awfully expensive to build on a per-missile basis compared to something like an Atlas.
Also, exactly how much enriched uranium or plutonium does each of these take versus total national production at the time?
They knew full well that it would take *years* to develop the powerplants, by which time the atomic industry would be further along.
Atlas was ten years away from being designed. At the time, a chemical rocket ICBM seemed dubious if it could even lift & throw sufficient payload.
Yeah, but as long as the Peenemunde team was working on ballistic missiles versus Sanger’s aerodynamic ones, you had to wonder “Do we want it to go at Mach 3-4 in the atmosphere, or at Mach 15 outside of it?”
Didn’t take that much imagination to figure out which would be harder to intercept, even in 1947.
Don’t forget the size of warhead that they were looking at, quite possibly too big for an ICBM.
Had chemical rockets not scaled as well as they did and/or warhead sizes not shrunk like they did[1] massive cruise missiles like this might have been needed, (as far as any intercontinental nuclear delivery system is needed).
[1] It’s downright scary how small they ended up, standing a meter away from the one in Caen and knowing that little thing is enough to remove the entire city from the map is a rather sobering experience.
I’d have to see the details of the reactor heat exchanger to judge if it would work or not. A ramjet requires a shock wave for compression where the fuel is injected and a bunch of thin reactor tubes would impede that flow and probably push the shock out of the intake.
The Tory reactors for Pluto didn’t have that problem.
I’m wondering about the effect of radiation from the reactor on the warhead. I’ve heard that having another nuke go off nearby can fission enough of the nuclear material to cause problems when the warhead is triggered. At least that’s the reported mechanism for some early interceptor designs.
I always thought it was more the intent to damage, with EMP, the electronics that controlled the detonation; though I could see where the blast from a near-by nuclear explosion could damage the incoming warheads enough to inhibit their performance (something like the “dense-pack” or “close-pack” – I misremember which is the correct term – theory of siting missile siloes relative to each other to where hitting one induces fratricide on a warhead hitting another).