TheMark 15 nuclear bomb, orMk-15, was a 1950s Americanthermonuclear bomb, the first relatively lightweight (7,600 lb (3,400 kg)) thermonuclear bomb created by the United States.
A total of 1,200 Mark 15 bombs were produced from 1955 to 1957. There were three production variants: Mod 1, Mod 2, and Mod 3. The design was in service from 1955 to 1965.
All three models were generally physically similar; weight of around 7,600 lb (3,400 kg), diameter of 34.4 to 35 in (87 to 89 cm), length of 136 to 140 in (350 to 360 cm).[1]
The Mod 1 corresponds to theCastle Nectar test of theZombie weapon prototype. This test had a yield of 1.69megatons of TNT (7.1petajoules).[2][3]
The Mod 2 corresponds to theRedwing Cherokee nuclear test of theTX-15-X1 test model, and had a yield of 3.8 Mt (16 PJ). Redwing Cherokee was the first US thermonuclear bomb airdrop test.[4]
The Mod 3 also appears to have had a 3.8 Mt (16 PJ) yield.
A missile warhead variant of the Mark 15, theW15 Warhead, was an ongoing project in the mid 1950s. It was canceled in early 1957. Before cancellation, it had been intended for use on theSM-62 Snark missile. Instead, the Snark ended up using the W39 (see below).
TheW39 nuclear warhead andB39 nuclear bomb used a common nuclearphysics package which was derived from the Mark 15. The experimental W39 devices were initially tested as theTX-15-X3 (which is identical to the W39 Mod 0 design).
On February 5, 1958,during a training mission flown by aB-47, a Mk 15 nuclear bomb, was lost off the coast ofTybee Island, Georgia nearSavannah.
Initially, experts disputed whether the bomb was nuclear or not. If it contains a plutonium core, it is a fully-functional nuclear weapon. If the core was replaced with a dummy, it would be non-nuclear but still capable of creating a conventional explosion. After the incident, the Air Force assured the public that the nuclear capsule was removed prior to the flight and fitted with a simulated 150-pound cap made of lead.
However, according to1966 Congressional testimony by Assistant Secretary of Defense W.J. Howard, the Tybee Island bomb was a "complete weapon, a bomb with a nuclear capsule" and one of two weapons lost that contained a plutonium trigger.
