The T-12 was a further development of the concept initiated with the United Kingdom's
Tallboy and
Grand Slam weapons developed by British aeronautical engineer
Barnes Wallis during the
Second World War: a hardened, highly aerodynamic bomb of the greatest possible weight designed to be dropped from the highest possible altitude. Penetrating deeply in the earth before exploding, the resulting shock wave was transmitted through the earth into targets. The resulting
underground cavity and
ground motion could also undermine structures. The bomb could also be used against hardened targets. These types of bombs can reach
supersonic speeds and have tail fins designed to spin the bomb for greater accuracy. Originally designed to meet a target weight (one half of the maximum payload for the
Convair B-36 "Peacemaker" bomber), with its hardened case the bomb weighed slightly less than . The final T-12 weighed . This was twice the size of the United States' previous largest bomb, the M110 (T-14), the American-built version of the British Grand Slam. The T-12 was not a simple scale up of the M110, but incorporated modifications based on testing and calculations. The B-36 was redesigned so it could carry the T-12, although a converted
B-29 Superfortress was used for testing. ==See also==