CONSTRUCTION. In SD 250 bombs having a hollow charge, the cavity is semicircular in section. The cavity in the SD 500 is a truncated cone, the larger diameter being 30 cms and the smaller diameter, 11 cms. (See fig. 8.)

The H.E. charge has a metal lining for the cavitiy which is supported on a flange and in order to permit the formation of the jet, the flange is located at a distance from the nose of the bomb of approximately 1.5 times the diameter of the cavitiy. The opening at the nose of the bomb is approximately 5 1/4 inches.

The 250 H.L. will penetrate 35 cms of armor plate. The 500 H.L. will penetrate 62.5 cms of armor plate or 350 cms of concrete. The performance figures for the 800 H.L. are not available but it appears that with an H.E. charge of 110 kg it was hoped to penetrate 100 cms of armor or 6 meters of reinforced concrete. They are generally filled with ama-tol 50/50 or 60/40.

The special nose device for use with SD 250 bombs consists of a hollow charge which is to be attached to a bomb of standard type. This charge which weighs about 4 kg is de-tonated by its own fuze located in the nose of the device. In order that detonation of hollow charge shall not damage the bomb, the space between the charge and the bomb is filled with a mixture of sawdust and cement.

REMARKS. Details of these types were obtained from documentary evidence only.

The SD hollow charge bomb proved disappointing in performance and modifications were made which resulted in the production of the H.L. type of bomb.

The special nose device for the SD 250 obtains greater penetrating power from low alti-tudes. It produces a hole in the armor through which bomb can pass. Bomb has a short delay fuze so that detonation of bomb will occur inside the target. Documents state that such a bomb will penetrate 7 cms of armor plate.

Figure 8 – SD and H.L. Hollow Charge Bombs