British Bomb, 22000 lb DP, Mk 1 Grand Slam
The bomb body is manufactured of cast steel, with a solid nose plug and with three exploders fitted 120° apart in the base plate. The bomb bodies are issued with exploders inserted, and the exploder tubes are sealed with shipping plugs.
The tail is attached to the after end of the bomb body by 12 studs. A cylindrical metal cowling, placed between the bomb body and the tail cone, enhances the streamlining of the bomb.
The bomb contains an explosive filling of Torpex, with a one-inch layer of TNT topping added to the after end. Four inches of wood- meal/wax composition is then added, and the filling sealed with a 1/2-in. plyboard washer. The three exploders pass through holes in this washer and are held in place by a heavy base plate, which is secured by bolts to the bomb body.
The special tail unit, No. 82 Mk I, is constructed of light alloy and consists of a cone to which are attached four fins of streamlined cross-section. The fins are set at an angle of 5° to the axis of the tail cone, giving a right-hand spin to the bomb as it falls. The tail fits over twelve 7/16-in. studs fitted into the bomb body, and is securely fastened to the studs by Simmonds nuts. Three handholes in the tail cone give ready access to the three tail pistols.
The bomb is suspended in the plane by twin suspension links. Each link is coupled beneath the bomb by a special Vickers release clip, capable of either electrical or manual operation. In addition to the suspension links, the bomb is positioned in the plane by a standard crutching system.
This bomb is designed for special operational uses, and its employment will be restricted to certain specified bomb commands. The initials “D.P.” signify its deep penetration characteristics, although the bomb is not designed for armor or concrete piercing. Rather it is intended to produce heavy shock waves as a result of the explosion of its main charge deep within the earth.
The bomb is carried on specially adapted Lancaster aircraft. The striking velocity of the bomb, when released at an altitude of 16,000 ft. and an air speed of 200 m.p.h., is stated at 1,097 ft./sec., at which speed it has developed a rotational velocity of 60 r.p.m.
The general arrangement of this bomb is identical to that of the 12,000-lb. D.P. Bomb “Tallboy”. The two bombs are identical in all respects, the 22.000-lb D.P. being merely an enlarged version of the 12,000-lb. D.P. bomb.
Grand Slam bombs made in the US differ somewhat in body construction from those made in Britain. The body is built up of five sections welded together. The solid nose and the base sections are made of forged steel, while the three center sections are made of rolled plate, longitudinally welded, taper-bored internally, and then set in a die to form the external contours.