British Bomb, 30 lb IB, Mk 1, Mk 2, Mk 2M, Mk 3, Mk 3M, Mk 4, Mk 4M
The bomb consists of a cylindrical body, with a hemispherical nose at one end and a tail at the other; the cylindrical tail strut being connected by four equi-spaced fins to the rear end of the tail cone.
The cylindrical body is made from welded tube, the forward end of which is reduced slightly to fit into the rim of the hemispherical steel-plate nose to which it is welded. The nose is pierced centrally and has a burster container welded into it and closed by a screwed plug, the outer surface of which conforms with the shape of the bomb nose. A flanged tail plate is welded in the rear end of the body, and has a hollow spigot through which the bomb is charged in the center. The spigot is closed by a screwed plug, and is threaded externally for the attachment of the tail. Riveted in the forward end of the tail cone is a diaphragm plate having a threaded boss, which screws onto the tail plate spigot to secure the tail to the bomb body. A 10 per cent air space is left in the body when it is filled. A 3-in. wide cylindrical strut is attached to rear of the tail cone by four fins spot welded to both strut and cone. The tail cone is closed by an end cap.
The bombs are carried in a Small Bomb Container, or suspended from a bomb carrier by a lug on a suspension band. S.B.C. 250# will carry eight bombs.
The 30 lb. Bomb Mk I is similar to the Mk IV except for the following differences. The burster container is screwed and welded into a flat nose plug, which is welded into the end of the body, and a hemispherical nose fairing fits onto the nose plug. The bomb employs the Nose Fuze No. 38, and is filled with 1.5 lb. of white phosphorus cast in the nose end of the body and approximately 6 lb. of a 5 per cent solution of rubber in benzole.
The 30 lb. Bomb Mk II is similar to the Mk IV, except that the body is made from drawn tube instead of being a welded tube; so the bomb functions by tail ejection of the filling; the tail plate and tail being blown off by the firing of the magazine charge in the fuze. The weight of white phosphorus cast in nose is 1.5 lb.
The Mk III is similar to the Mk IV, except that the body is of heavier gauge metal.
The Mk IIIM is similar to the Mk III, except that body has two external pads to locate a suspension band with lug, which may or may not be used.
The Mk IIM is similar to the Mk II, except that the body has two external pads to locate a suspension band with a lug, which may or may not be used.
The Mk IVM differs from the Mk IV only in that it has a suspension band with a lug.