In parallel with the tactical bomb of high power Mk.7, but based on the same 92-lens nuclear charge in 1950, a bomb Mk.12 "BROK" was developed. If Mk.7 was created a maximum bomb bomber for a tactical fighter of a tactical power aircraft, the Mk.12 was conceived as a bomb of minimum size and weight, but with a better utilization rate of fissile materials than cannon-type bombs. The nuclear charge Mk.12 had a smaller diameter than Mk.7 and, correspondingly, a smaller compression ratio of the nucleus and the TNT equivalent. Tests of charge Mk.12 took place in the spring of 1952 in two explosions of 12 and 14 kt.
The serial production of the tactical atomic bomb Mk.12 began in December 1954. Up to February 1957, about 450 bombs of three modifications were produced: Mod.0, Mod.1 and Mod.2. The Mk.12 had a ballistic body length of 3940 mm and a diameter of 560 mm. The mass of the bomb was only 500 kg. The tail feathers had four planes, deflected at take-off in a position close to horizontal. Kok and Mk.7, Mk.12 stabilized but the trajectory by rotation, for which but the planes of the stabilizer had a small slat. The Mk.12 bomb was equipped with the same detonation system as Mk.7, which included one radio altimeter, two timers and a contact piezoelectric fuse. Accordingly, the automatic detonation had the same seven operating modes. The mechanism of the automated installation in the flight of a nucleus from fissile materials was also borrowed from Mk.7.
Unlike the rather heavy Mk.7, the Mk.12 bomb allowed a higher speed of the carrier aircraft, although it was never actually used with supersonic aircraft. The main carriers of Mk.12 were fighter-bomber modifications of the famous "Saber" - F-86F (after the 35th series) and F-86H, as well as the deck fighter-bomber F9F-8B "Cougar" equipped with the LABS system. To carry a more powerful bomb Mk.7 these planes could not because of the short racks of the chassis. The bomb Mk.12 under the wing of the fighter-bomber F-86H was suspended, but one of the two pylons, spaced fairly wide on the wing. At the same time, the atomic bomb was suspended under the left plane, under the right one, a 455-liter fuel tank was mandatory. In 1954-1955, a total of 265 F-86F and 475 F-86H equipped with the LABS system were built.
The Mk.12 had the same nuclear charge as Mk.7, but with a reduced mass of explosives in the focusing system. The trotyl equivalent of the charge Mk.12 was 10-20 kt (in Mk.7 - up to 70 kt with the same amount of damage-235). Therefore, the kok tactical strike system, the F-86 / Mk.12 complex was considered significantly less efficient than the F-84 / Mk.7. In 1958, the F-86H fighter-bombers were withdrawn from the armament, and the F-84G / Mk.7 complex was replaced by a supersonic F-100D / Mk.7. For the new carriers, the Mk.12 bomb was unnecessary, and in 1958, it was withdrawn from service. The last Mk.12 was disposed of in 1962.
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