The Flying Crowbar–America’s Doomsday Weapon

Artist's impression of the Flying Crowbar's general outline.

Artist’s impression of the Flying Crowbar’s general outline.

Humans are really, really good at coming up with ways to kill one another. From the first cave man who made the intellectual leap that tying a stick to a rock would make a nasty stabbing weapon to the current crop of high tech weapons designers, people have long put a premium on finding more efficient means to kill. One might think this homicidal tendency might have been curbed when we figured out how to split the atom and opened up the very real possibility of self-induced extinction, but it turned out the opposite was true. The nukes got bigger and badder, and the systems to deliver them became more powerful and accurate.

During the race to build stronger and stronger nuclear weapons, one project even gave the staunchest ally of nuclear power pause. It was a weapon so nasty that it could not even be properly tested for fear it would fly out of control and devastate friend and foe alike. This potential doomsday machine was dubbed Project Pluto, although it came to be known by its more ungainly nickname, the Flying Crowbar.


A post Sputnik world

Sputnik I, the basketball sized satellite that changed the world.

Sputnik I, the basketball sized satellite that changed the world.

The launch of Sputnik, the first artificial satellite, sparked a frenzy in America. Not only was Sputnik itself a defeat for America, showing just how far behind it was in the Space Race, it showed that the Soviets could produce powerful rockets that could potentially reach the US. At the time, no missile in the inventory could match the Soviet capability. It also pointed to the disturbing possibility that the Soviets might have a better anti-missile defense system than the US. Such a system could upset the delicate balance between the US and Soviet Union. If the Soviets knew they had a reasonable chance of surviving a nuclear exchange, they would be more likely to pull the trigger on an apocalyptic confrontation.

That was when someone within the Pentagon conceived of a simple but nasty idea. Dubbed SLAM (Supersonic Low-Altitude Missile), the weapon would be a cruise missile powered by nuclear ramjet power. The project to build the reactor was dubbed “Pluto”, a moniker that came to be used to describe the entire weapon system. The name Flying Crowbar came later, used to illustrate the durability of the system.

At the core of this ultra-durable doomsday weapon was a simple concept: the ramjet. It has been the working concept behind jet engines sine the first prototypes in the 1930s. Air is sucked into a nozzle, where it is then heated. the air expands, and blows out the rear nozzle of the craft, thus providing propulsion. In most jets, the heating is achieved by burning hydrocarbon fuels. In The Flying Crowbar, an unshielded nuclear reactor would provide the heat. This gave the advantage of an almost limitless operational lifespan. As long as the nuclear core could undergo fission, the Flying Crowbar could sow death and destruction.

One distinct disadvantage of the system was the very thing that gave it its advantage–the nuclear reactor. Most nuclear reactors are quite sanely tucked behind layers and layers of concrete, because they have  a tendency to spew a lot of radiation. The Flying Crowbar’s reactor would be housed in a missile the size of a locomotive, flying at a low altitude over friend and enemy alike. Planners predicted that the shockwave from the weapon passing overhead might be enough to kill people on the ground. If that didn’t do it, radiation spewing out of the reactor would finish the job.

If the weapon were to be used in anger, it would first be launched into the air by rockets, where it would start to circle high in the air before being given the final order to drop in for its attack run. The death machine would be loaded with a dozen hydrogen bombs, which would be lobbed at targeted Soviet cities once it reached Soviet airspace. When the nuclear payload was exhausted, the Flying Crowbar could then be flown back and forth across Soviet territory, flattening and irradiating anything in its path. Since it would be flying at a low-altitude at speeds in excess of Mach 3, the had nothing that could stop it.

But neither did the US. The Flying Crowbar would become an autonomous weapon with a nigh limitless fuel supply that could continue to wreak destruction long after its handlers perished. A doomsday weapon of the highest order.


Early enthusiasm gives way to doubt

Work on Project Pluto began January 1, 1957, at the Lawrence Livermore National Laboratory. The scientists there had their hands full, as every aspect of the Flying Crowbar tested the limits of material science known at the time. The whole point of using a nuclear reactor was that it burnt hotter and longer than any other known fuel source. The heat would give the craft the speed it needed to evade Soviet defenses. The heat created a problem though, mostly because no material used in aircraft engines could stand up to it. That, and the sheer pressure of the air shooting out the nozzle could be enough to rip open the rear of the craft. Those issues aside, a nuclear reactor small and light enough to go airborne would have to be built.

The prototype reactor that would form the core of Project Pluto was dubbed “Tory.” A static version of the engine system was tested on May 14, 1961 at a specially made test site in the Nevada desert. The test site was suitably massive for such an ambitious project. Site 401 occupied eight square miles of Jackass Flats. A fully automated two mile long railroad was constructed to transport the “hot” reactor from the test site to a secure building where it could be disassembled via remote control. Scientists were going to watch the tests via a TV feed from a secure site. A fully stocked fallout shelter was located on site, just in case.

Tory II, one of the nuclear ramjet engines tested at the Nevada Test Site.

Tory II, one of the nuclear ramjet engines tested at the Nevada Test Site.

The disassembly building was built with six to eight foot thick concrete walls. The government bought an aggregate mine to provide the material. Twenty-five miles of oil well casing were used to store a million pounds of pressurized air used in the test. A five minute test would require forcing a ton of air through huge steel tanks heated to 1350F.

The day of the test, the engine fired perfectly, although it ran for only a few seconds at partial power. But it didn’t explode, catch fire, or otherwise spew radiation all over the test site. So the test was considered a success.

As the team continued to develop reactors out in the desert, the once eager Pentagon planners began to have doubts. For one, they wondered if the Flying Crowbar could perform the mission as designed. it was supposed to be what amounted to a stealth weapon, but given how hot and loud the thing was, the Soviets could probably see it coming a long ways away (whether they could stop it once they spotted it was another matter.)  Plus, the weapon would inevitably pass over allied territory on its way to destroy the Soviet Union. Spewing radiation over friendly territory would not be great for diplomatic relations, should anyone survive an incident that required deploying the Flying Crowbar, that is.

The biggest problem was that there was no way to safely test the Flying Crowbar. Testing it over the Nevada desert was a non-starter. It would be too easy for the system to slip its proverbial leash and devastate an American city. One solution proposed to this problem was to fly the missile in figure eights near Wake Island, then bury it in 20,000 feet of water once the test was done. Even in the heyday of the nuclear craze, this was not an attractive option.

Those issues aside, it quickly became apparent that Project Pluto was obsolete before it was even finished. The Air Force began to deploy Titan and Atlas missiles, ICBMs that could hit harder and faster than the Flying Crowbar, with less risk of collateral damage. On July 1, 964, Project Pluto was cancelled. the advances in material science gained during the ill fated project were boons to the space program and rocketry alike. Other than those contribution, Project Pluto is dead and buried, a weapon too terrible to contemplate. A real life, honest to god, Doomsday Device.



Herken, Gregg. “The Flying Crowbar.” Air & Space Magazine. April/May 1990. Volume 5, no. 1. pg 28.

Nevada National Security Site. “Project Pluto.” August 2013.

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