Mark 11 nuclear bomb

• Name — Mark 11 nuclear bomb • Origin — United States • Type — Nuclear weapon • Is Explosive — yes • Production Date — 1956-1960 • Developed From — mark 8 nuclear bomb • Number — 40 • Weight — 3210 - • Length — 147 in • Diameter — 14 in • Filling — Highly enriched uranium • Yield — 25 -

As with the Mark 8, the Mark 11 was a gun-type nuclear bomb (see also: gun-type assembly weapon). It used a fixed large target assembly of highly enriched uranium (HEU), a gun-like barrel, and a powder charge and a uranium bullet or projectile fired up the barrel into the target. The Mark 11 was first produced in 1956, and was in service until 1960. A total of 40 were produced, replacing but not expanding the quantity of Mark 8 bombs. It was 14 in in diameter and 147 in long, with a weight of 3,210 to. Yield was reportedly the same as the Mark 8, 25 to 30 kilotons. Both the Mark 8 and the Mark 11 were compatible with the same fissile material "gun cores", but the Mark 11 had a much more modern external casing designed to penetrate further and more reliably into the ground. The Mark 8 had a flat nose, much like a torpedo. The Mark 11 nose was a pointed ogive shape. The MK-11 also known as the MK-91 had variable yields by changing the target rings. A major difference over the MK-8 was that the MK-91 had an electric operated actuator as a safety device that would rotate a spline ring to prevent the projectile from being fired into the target rings. The MK-8 had no safety devices. Upon release from the delivery aircraft detonation would occur after the black powder fuzes burned 90-110 seconds. The MK-91 was a deep penetrating weapon in many surface materials. A "PHOEBE" polonium neutron initiator increased the nuclear detonation efficiency.