During the height of the Cold War history of 1950s SAC or the Strategic Air
Command, America's nuclear strike force was looking at the next generation of
nuclear delivery systems, bombers were the backbone of SAC but were slow and
vulnerable to Soviet air defenses, ICBMs were still in their early stages had not
yet reliable enough but from research into nuclear powered jet engines came an
idea for one of the most insidious weapon systems ever devised.
As the Cold War developed and deepened both the US and the Soviet scrambled to
create ever more effective ways to deliver and defend themselves from
nuclear attack. In the US a system was proposed that the nuclear planners would
call "The big stick". In a little over ten years since the first atomic bombs had
been dropped on Japan, the technology moved on rapidly SAC had a fleet of
long-range nuclear bombers using the B-52, keeping a number of these in the
air 24 hours a day 365 days a year flying around the Arctic on constant
alert. One of the problems with the bombers at the time was that they were
limited by their fuel capacity to fly around whilst on alert. To combat this
the U.S. set out to develop a nuclear-powered bomber, if this could be
done then their flight time and range would only be limited by how long we
could keep the crew up there. However they soon found out that the shielding
required to protect the crew from the nuclear powered engines weighed so much for
it made them slow and used up most of the payload capacity, not to mention the
handling problems of such a dangerous propulsion system for the ground crew.
But from this research came a ceramic reactor core small enough to be used in
an unmanned plane or cruise missile that wouldn't need any heavy shielding. In
1955 the US Atomic Energy Commission asked for Lawrence radiation laboratory
to do a feasibility study on using the new ceramic reactor to power a ramjet
engine and in 1956 the USAF issued system requirement No. 149 for a
nuclear-powered winged missile. The project was called Pluto after the code
for the ceramic reactor developed by the Lawrence radiation laboratory and the
name given to the cruise missile was SLAM or Supersonic Low-Altitude Missile
but also it was unofficially known as the big stick.
Although ramjets were quite well known at the time no one had proposed
using a nuclear reactor as the heat source instead of the usual solid rocket
fuel or liquid fuel. A ramjet works by using the forward speed of a vehicle to
compress the air instead of using a turbofan compressor in the engine like a
normal jet does. This compressed air is then mixed with a fuel which when burned
expands and creates its thrust. Although a ramjet can achieve speeds of up to Mach 6
they don't normally start working efficiently until its speed is over Mach 2
and as such they are normally launched by small rockets to bring them up to
speed before the ramjet takes over. In a nuclear-powered ramjet to the compressed
air is channeled through the reactor core which would heat up the air in the
same way as if you burned the fuel. This expanded hot air is then what produces
the thrust required. Even a small reactor core will create an immense amount of
heat for weeks or months effectively providing an almost unlimited fuel
supply as far as the mission duration was concerned. Nuclear reactors of the
time we usually large structures surrounded by lead and concrete so to
make one that will be small enough and light enough to fly would rely upon some
radical advances in material technology and this is where the ceramic core came
in. The nuclear ramjet engine would also have to operate at temperatures higher
than any conventional jet or rocket engine while also been exposed to the
intense radiation which would affect its electronic control systems and it would
also have to be able to fly for extended periods of time in any weather. With no
pilots or active remote control like we see in military drones of today it would
also have to find its own way around. To do this a new groundbreaking guidance
system was developed called TERCOM. This used a downward looking radar which
compared its results to a terrain map which it carried onboard. The flight path
to the targets were then plotted onto the terrain map and this would enable it
to fly unaided deep into enemy territory. SLAM would also use an electronic
inertial guidance system control and telemetry but these had to be made to
withstand the intense radiation as any standard electronic components would
have been fried in a matter of minutes. With a fuel supply but could last for
weeks or months this gave it the possibility of being launched in a time
of emergency to fly around the oceans in a holding pattern close to the target
until the order was given to carry out its mission. Slam was designed to carry
not one but multiple nuclear warheads the idea being that it would fly to its
designated target release its nuclear weapon before moving on to the next
target releasing his weapon and in so on and so forth until all the targets had
been hit and doing so whilst traveling at Mach 3 just a few hundred metres
above the ground. This is all pretty advanced stuff even today but this was
the mid-1950s. To test the prototypes a section of desert locally known as
Jackass flats which was around 310 square kilometers or 120 square miles
was set aside at the Nevada national security site where the US tested its
nuclear weapons and ultimately where all the nuclear engines including the NERVA
nuclear Rockets would be developed. In order to test a system they had to
simulate the volume and temperature of the air that would be expected during
its Mach 3 flight at sea level. This was well beyond anything any wind tunnel
could provide so they built pressurized air supply using miles of 10-inch oil
pipes bolted together to create a total capacity of 545,000 kilograms of
air at a pressure of 3600 psi. This was then passed through a massive heat
exchanger to raise the temperature to 500 degrees Celsius at a flow rate of
325 kilograms of air second to simulate the conditions that
the ramjets Inlet diffuser will be expected to
handle. So much air was required to do a 90 second test but it would take two
days to pressurize the system using huge compressors borrowed from the US Navy's
submarine base in Connecticut. To create enough energy to propel slam and carry
a payload it was calculated to require a 500 megawatt reactor but to test its
viability they first had to build a smaller prototype this was called the
Tory-IIA and would be one-tenth of a power at 50 megawatts.Because the
reactor core would be cooled by incoming air, the pressures involved at Mach 3
inside the reactor core not only from the compression of the air but also the
rapid heating would be up to thousands of pounds per square inch in certain
areas. To do this the Tory-IIA's air cooled core would be made up of over a
100,000 pencil-sized hexagonal ceramic fuel elements made from
beryllium oxide and enriched uranium dioxide. These were stacked in to end in
the thousands of airflow channels in the core and because they were unattached to
each other this minimized the thermal stress on the system. The reactor was
then attached to a ramjet and the whole thing was mounted on a
rail car that was shunted from its disassembly building to the test area by
a remote-controlled locomotive. In 1961 the Tory-IIA was test-fired for 45 seconds,
although the results would consider success it wasn't a complete fly ready
system, its power was too low and it had external water-cooled control
rods in the reactor. The final test would need a full sized version that was
completely air-cooled with the inlet and exhaust ducts fitted to prove they had a
flight ready nuclear ramjet engine. It would take three more years before the
full-sized 500 megawatt version called the Tory-IIC was ready for testing.
This will be the size of a locomotive and weighed about 6300kg.
Because everything in the reactor was air-cooled the pneumatic
actuators that operated the control rods which increased or decreased the power
had to operate at 650C if these failed or jammed it
would prove impossible to shut down the reactor once at full power. On the 20th
of May 1964 the Tory-IIC was rolled out to the test area and connected to an
expanded air supply. The test ran for five minutes at full power and after
they have brought back the reactor and stripped it down for inspection, they found
it it worked perfectly there was no damage to be inside of a core all the
pneumatic actuators or the electronics. The next stage would be to flight test
it with a missile airframe but the problem was where they couldn't fly over
populated areas of land as a crash could spread the highly radioactive material
so the plan was to launch it in the Pacific Ocean and in fly it around and
then crashed into one of the nuclear test sites where the atomic bombs have
been detonated. But slam would never reach his flight
test stage and on the 1st of July 1964 the program was cancelled. The world was
changing fast, the shock of the Cuban Missile Crisis had led the U.S. and the
Soviets to banning above-ground nuclear tests and as such this would also affect
slam. By 1964 ICBMs had advanced to such a point where they were seen as a
superior system that was both easy to build and maintain reducing the need for
such a super cruise missile. There was also another reason during the
development it was found that if they changed the design of a fuel rods
slightly the exhaust of ramjet could be made highly radioactive this would make
it a vengeance weapon that would not only fly around dropping its nuclear
bombs on its targets but afterwards it could continue to fly at
just a hundred meters above the ground not only causing damage with the
huge shockwave it created but also spewing out radiation and poisoning
everything in its path until its reactor core failed which could take weeks or
months. The government decided that it was just too provocative and dangerous
and if they deployed this effectively unstoppable weapon then the Soviets will
be forced to develop their own version. Although slam was never made much of its
technology especially the guidance system is now used in modern cruise
missiles. So what do you think of America's big stick let me know in the
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