D.P. 12,000-lb. Mk I, "Tallboy" (Service)

Fuzing

Color markings

Tail No.

Over-all length

Body diameter

Body length

Wall thickness

Tail length

Tail width

Total weight

Charge/weight ratio

Body Construction: 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 bombs 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 me-tal cowling, placed between the bomb body and the tail cone, enhances the streamlining of the bomb.

The bomb body 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 add-ed, and the filling sealed with a ½-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.

Tail Construction: The special tail unit No. 78 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 slight 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 hand-holes in the cone give ready access to the three tail pistols.

Suspension: 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 to either electrical or manual operation.

In addition to the suspension links, the bomb is positioned in the plane by a standard crutching system.

Explosive Components

Detonator – Sensitive type, delays up to 60 min. as required operationally.

Exploders

Primary: 2 ring and 2 solid C.E. pellets; 4 solid RDX/Beeswax pellets.

Secondary: 2 ring and 2 solid large RDX/Beeswax pellets (placed in a special exploder tube into which the standard exploder container fits).

Filling – Approximtaley 5,200 lb. Torpex surmounted by a 1-in. topping TNT.

Remarks: 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 pe-netration characheristics, atlhough the bomb is not designed for armor or concrete pier-cing. Rather, it is intended to produce heavy shock waves as a result of the explosion of its heavy 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 18,000 ft. and an air speed of 200 m.p.h., is stated at 1,097 ft./sec., at which speed is has developed a rotational verlocity of 300 r.p.m.

The filling and exploder system of this bomb is identical to that of the 22,000-lb. D.P. Bomb, "Grand Slam". The two bombs are identical in all respects, the 22,000-lb. D.P. be-ing merely an enlarged version of the 12,000-lb. D.P. Bomb.

Figure 28 – D.P. 12,000-lb. and 22,000-lb. Bomb