The Davy Crockett recoilless rifle was the smallest nuclear weapon ever deployed by the US.
Davy Crockett warhead on exhibit at the National Museum of Atomic Testing in Las Vegas. My hand shows the scale.
By the early 1950s, in addition to the Army’s use of a gun-type configuration in its nuclear Atomic Annie artillery shells, work was also carried out on a new way to implode plutonium, known as “two-point linear implosion”. Rather than a round core surrounded by a shell of explosive lenses, linear implosion used a bare oblong core of plutonium or uranium, with no tamper and with just enough surface area to keep it barely below critical mass, and placed a cylinder of explosive around it. When set off by detonators at each end, an inert “wave shaper” or “flying plate” at each end is pushed by the shock waves into the oblong ends of the nuclear core, forcing it into a roughly spherical shape that would briefly form a supercritical mass and produce a nuclear explosion. These weapons were very inefficient in their use of fissile material and typically produced very low yields (ranging from sub-kiloton to several kilotons), but they had the advantage of being extraordinarily small and lightweight—as little as six or eight inches in diameter.
This advance made possible the use of nuclear devices in a whole array of small deliverable packages, and the Army, which had always been limited by the size and weight of nuclear weapons to using them only in tactical missiles like the Honest John or in large-caliber artillery guns like Atomic Annie, now began to contemplate supplementing a number of weapons systems with nuclear equivalents. The Pentagon referred to this as “more bang for the buck”, and Army doctrine began to consider these tiny nuclear weapons not as specialties that were only to be used in the direst of circumstances, but as ordinary weapons that could be deployed and used on the battlefield just like any other ordinary infantry weapon.
One of these tiny nuclear weapons was the Davy Crockett.
In January 1958, the Army’s Ordnance Division began a project at the Picatinney Arsenal in New Jersey to develop an anti-tank recoilless rifle with a nuclear warhead, called the Battle Group Atomic Delivery System (BGADS).
The conventional recoilless rifle (sometimes called a “bazooka”) had a shaped-charge warhead which used explosives to focus its energy and push a cone of metal into a molten jet of high-speed material that could punch through the armor of an enemy tank and destroy it. Although recoilless rifles were made in a wide variety of sizes, the smallest of these were man-portable and could be easily carried around on the battlefield by a crew of men who could load and fire it as targets presented themselves.
The linear-implosion warhead, however, which was designated W54, had an explosive equivalent yield of just 10-20 tons of TNT (not kilotons).The complete round was 31 inches long, 11 inches wide (it was nicknamed “the atomic watermelon), and weighed 76 pounds.
The BGADS was also designed to be man-portable and easily-movable. But instead of striking one single tank, the nuclear warhead inside the BGADS would be capable of knocking out several tanks at once. Especially effective would be the neutron radiation that would be sent out by the explosion, which could reliably kill troops anywhere within a quarter-mile of the detonation, even through tank armor or heavy cement walls. This made it an early example of a “neutron bomb”, which killed people by radiation but did not damage buildings with its limited blast. The explosion would also irradiate the ground in the immediate area, making it impassable for a number of days.
In August 1958 the BGADS system was accepted for deployment and was officially designated the M28 Davy Crockett Weapons System. The120mm tripod-mounted launcher had a range of 1.25 miles, and a dial on the warhead allowed the crew to select the proper height above ground for the detonation. A short time later, a larger version of the launcher appeared, designated the 155mm M29, which used the same nuclear warhead but had a range of 2.5 miles, and was usually mounted on the back of a Jeep or atop an armored vehicle. Although it weighed over 400 pounds, the M29 launcher’s backblast would damage the vehicle it was mounted to, so it had to be detached and man-carried a short distance away before firing.
The weapon had a three-man crew. Once a target was identified, the gunner would fire a single 37mm shell (attached to the Davy Crockett’s barrel tube) as a “spotter” to find the proper range and firing angle. The protruding pipe at the tail of the projectile was then fitted into the recoilless rifle tube and was fired by pulling a trigger, which set off the propellant charge inside the tube. Four fins inside the tail would pop out on the way to the target to stabilize the warhead in flight.
Despite being called a “recoilless rifle”, the Davy Crockett’s barrel was actually smoothbore and had no rifling, and it was technically a “spigot gun”. The lack of rifling crippled the system’s accuracy, but it was assumed that with a nuclear shell the accuracy wasn’t all that important. The crew was however advised to fire the weapon from behind cover, such as an earthen bank or a thick wall, especially when shooting at short range–to give protection to the crew from the warhead’s neutron radiation.
The Davy Crockett was specifically intended to knock out tanks. This requirement was necessary because the Soviets had built up a massive tank corps during the Second World War, producing T-34 tanks (considered to be one of the best of the war) in stupendous quantities. As the US and USSR entered the Cold War, the Russians maintained their huge conventional military forces, and they far outnumbered NATO forces. Because NATO’s conventional forces alone would not be able to stop a full-scale Soviet armored thrust into Western Europe, NATO adopted the official policy of using tactical nuclear weapons first in response to any Russian invasion of the west, and would use nukes to halt the advance of the Soviet tank columns even if the Russians did not use any nuclear weapons. The Davy Crockett was designed with that specific task in mind.
By 1961, around 2,100 Davy Crockett warheads were being deployed by forward units of the US Army in Germany, concentrated particularly in the Fulda Gap, through which it was assumed any Warsaw Pact invasion would come. The weapon was also deployed to forward bases in Guam and Korea, for use against a possible invasion of South Korea by the North. The Davy Crockett was provided to specially-trained units of the 82nd Airborne Division, along with air-droppable half-ton trucks which could be fitted with the M29 launcher.
The nuclear system was only test-fired twice. In July 1962, two tests dubbed “Little Feller 1” and “Little Feller 2” were carried out at the Atomic Testing Site in Nevada. In the first test (confusingly named “Little Feller 2”) the warhead was static-fired a few feet above the ground, and in the second test it was live-fired by an Army crew from an operational Davy Crockett M29 tube. A short time later, the US signed the Limited Test Ban Treaty, so Little Feller 1 was the last open-air atomic test carried out by the US.
The weapon had practical issues as well as political. At short ranges it presented almost as great a danger to its crew as it did to its target. Critics were also alarmed by the Army’s entire “bigger bang for the buck” concept, arguing that it lowered the threshold for the use of nuclear weapons to an unacceptably low level and made all-out nuclear warfare more likely.
By 1967, the Davy Crockett was already being withdrawn from its forward bases and was replaced by new tactical missiles. By 1971 there were no longer any of the warheads in service.
Today, Davy Crockett casings are on exhibit at the National Museum of Atomic Testing in Las Vegas, at the National Museum of Nuclear Science and History in New Mexico, and in museums at Cape Canaveral Air Force Station in Florida, Fort Benning in Georgia, Fort Lee in Virginia, Watervliet Arsenal in New York, West Point in New York, and Fort Campbell in Tennessee.
3 thoughts on “The Davy Crockett Nuclear Weapon”
Was that the same device used in the “nuclear backpack”?
It may have been the inspiration for childhood jokes I recall about nuclear hand grenades that made larger craters than a soldier’s throwing distance.
Yes, both the Davy Crockett and the Special Atomic Demolition Munition (SADM) used the same W54 warhead. The SADM version had an adjustable yield that went up to one kiloton.
The “nuclear hand grenades” are an urban myth–you just can’t get a critical mass that small. The Crockett was the smallest nuke that the US ever made.
Yeah, the only reference I ever heard to grenades was a joke that went something like:
“Did you hear that they invented a nuclear hand grenade? Makes a hole fifty yards wide and ten yards deep. Problem is, the average solder can only throw it twenty yards.”
Which isn’t too far from the truth of the Crockett.