The W49 was an American thermonuclear warhead, used on the Thor, Atlas, Jupiter, and Titan I ballistic missile systems. W49 warheads were manufactured starting in 1958 and were in service until 1965, with a few warheads being retained until 1975.
The weapon itself was a Mark 28 Y1 warhead modified for the missile role.
The PGM-19 Jupiter was the first nuclear armed, medium-range ballistic missile (MRBM) of the United States Air Force (USAF). It was a liquid-propellant rocket using RP-1 fuel and LOX oxidizer, with a single Rocketdyne LR79-NA (model S-3D) rocket engine producing 150,000 lbf (670 kN) of thrust. It was armed with the 1.44 Mt (6.0 PJ) W49 nuclear warhead. The prime contractor was the Chrysler Corporation.
The Jupiter was originally designed by the US Army, which was looking for a highly accurate missile designed to strike enemy states such as China and the Soviet Union. The US Navy also expressed an interest in the design as an SLBM but left the collaboration to work on their solid-fuel Polaris. Jupiter retained the short, squat shape intended to fit in submarines.
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