Low, Loud, and Hot. Real Hot.

Old but good article on the SLAM (Supersonic Low-Altitude Missile), also known as ‘Project Pluto’ and the ‘Flying Crowbar.’

This baby was to be a nuclear ramjet-powered Mach-3 intercontinental cruise missile with a maximum range of over 100,000 miles and room for up to 26 hydrogen bombs to be dropped on the specified address as it passed over. Besides the bombs, the sound and heat of the thing’s passage at 1000 feet would have left wanton destruction in its path and the radioactive output of the ramjet would have been dangerous.

I think all I knew about this I learned in the description of an Estes model rocket of the thing back in the early 80s. I don’t believe Estes’ version had a nuclear ramjet.

Question: What would have limited the range of this thing? If the nuclear reactor was used to heat the air in the ramjet, wouldn’t range have been pretty much unlimited? Or was the range really dictated by how long the structure could hold up to the heat and stress of flight?

The SLAM was canceled in 1964.


  1. Well, I can’t claim to be an expert on any of this, but I’m pretty sure the thing just would have melted into a big firey radioactive pile. I don’t think any kind of substance could have resisted such heat and stress.

  2. 100000 miles is pretty much the equivalent to unlimited range. A flying reactor is going to be running lean fuel wise. The missile would be fine as the air would act as a coolant for the reactor. The real problem, is that no one has made a mach 3+ plane that withstand extended (24 hour +)high speed flight, more over who would want this thing paroling?

  3. The reactor is running very fuel lean, as in no fuel at all. Coldish air comes in the front, get’s heated up, and comes out the back producing thrust. That is the charm, of a nuclear ramjet, if the reactor could be made strong enough not to self destruct, it would run forever.

  4. Damn!

    As an engineer, I would have given both testicles (and my liver too) to work on a project like that.

    Alas, I was born 50 years too late….

  5. jaymaster, keep your liver, you need it to live. Well, some of it. You can lose about two thirds of it and still be OK. The rest will grow back.

  6. Range would be limited by how much structural damage is received by enemy fire and heat erosion.
    Obviously this weapon was designed to fight “the Last War”.

  7. Bet if you stuck a GPS nav system, automated flight controls, etc (Globoal Hawk system) on an SR-71 an powered it with a pair of these things it would work just fine. Funny thing about titanium hull and fuselage construction.

  8. Heh.. nuclear-powered SR-71. At least THAT wouldn’t be leaking fuel and other fluids all over the tarmac. 🙂


  9. SR-71’s are a gift from the aeronautical gods and should only be viewed in terms of awe and respect, don’t even dream about sticking one (or two) of those pluto reactors on one…That is sacrilege.

  10. I’m just saying, using the same materials and design techniques that gave us the SR-71, you COULD develop something like it that would last…hehe, hell, I wonder if you could launch it off the back of a ’71 using the drone pylon…

    Good god no, I would never DREAM of putting that kind of engine in a ’71…what a horrible thought! Something that wouldn’t leave a radioactive exhaust trail and could go trans orbital…

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