Deep Penetration Bombs
Peter Voß
Introduction
These bombs were designed for special operational uses to give deep penetra-tion of the earth and to produce heavy shock waves as a result of the explosion of their main charge. They have a charge/weight ratio of about 45 %, and are not intended for use as armor- or concrete-piercing bombs.
The two sizes of bombs are identical in all respects, the 22,000/lb. D.P. being merely an enlarged version of the 12,000/lb. D.P. A rather unusual feature of these bombs is the use of a cowl between the bomb body and the tail assembly to enhance their streamlining.
Both D.P. bombs are tail fuzed only, each bomb using three Tail Pistols No. 58 located 120 degrees apart in the base plate.
These bombs have been adapted by the U.S. for service use after slight modifi-cations in the method of construction.
D.P. 12,000-lb. Mk I, “Tallboy” (Fig. 31)
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Fuzing Color markings Tail No. Over-all length Body length Body diameter Wall thickness Tail length Tail width Total weight Charge/weight ratio
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Three Tail Pistols No. 58 Mk I Dark green over-all; red band near nose No. 78 Mk I 21 ft. 10 ft. 4 in. 3 ft. 2 in. Near tail, 1.25 in.; near nose, 4.1 in. 10 ft. 8 in. 3 ft. 6 in. (across fins) 11,885 lb. 45 % (approx.)
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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 metal 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 woodmeal/wax composition is then added, 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-sec-tion. 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 tail 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, cap-able of 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:
Detonators - 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 - Approximately 5,200 lb. Torpex surmonted by a 1-in. topping of TNT
Remarks: This bomb is designed for special operational uses, and its employ-ment 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 heavy main charge deep within the earth.
The bomb is carried on specially adapted Lancaster aircraft. The striking velo-city 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 it has developed a rota-tional velocity 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. being merely an enlarged version of the 12,000-lb. D.P. Bomb.
D.P. 22,000-lb. Mk I, “Grand Slam” (Fig. 31)
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Fuzing Color markings Tail No. Over-all length Body length Body diameter Wall thickness Tail length Tail width Total weight Charge/weight ratio
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Three Tail Pistols No. 58 Mk I Dark green over-all; red band near nose No. 82 Mk I 25 ft. 5 in. 12 ft. 6 in. 3 ft. 10 in. Near tail, 1.75 in.; near nose, 7.75 in. 13 ft. 4 in. 4 ft. 4 in. (across fins) 22,400 lb. 42 % (approx.)
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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 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 body contains an explosive filling of Torpex, with a one-inch layer of TNT topping added to the after end. Four inches of woodmeal/wax composition is then added, 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. 82 Mk I, is constructed of light alloy and consists of a cone to which are attached four fins of streamlined cross-sec-tion. 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 tail 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, cap-able of 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:
Detonators - 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 - Approximately 9,200 lb. Torpex surmonted by a 1-in. topping of TNT
Remarks: This bomb is designed for special operational uses, and its employ-ment 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 heavy main charge deep within the earth.
The bomb is carried on specially adapted Lancaster aircraft. The striking velo-city 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 rota-tional 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 U.S. 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.
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