Apparatus A.D. Type B Mk I (Obsolescent)

Over-all length

Diameter

Total weight

Propellant

Propellant weight

Charge igniter

Separate Charge

Mine wire

Bomb

Bomb weight

Explosive

Explosive weight

General: This rocket is employed to lay a curtain of aerial mines in the path of low-level or dive-bombing aircraft attacking a ship.

Description: The tail of the rocket consists of a center tube containing the propellant charge, the gases from which emerge through the venturi to propel the projectile. The propulsive force continues for about 1½ seconds. Around the center tube is fitted a fai-ring to which are attached tail fins, protected by a cylindrical shroud. The electric igniter leads pass through the tail fins, enter the center body of the rocket, and lead to the electric igniter. Connected in parallel to the igniter is an electrically fired time fuse, which burns through to ignite the separating charge. The separating charge is fired after about 10 seconds flight time, and ejects the contents of the rocket head, which consist of the bomb, the mine wire, and the parachutes.

Operation: When the separating charge is ignited, the outer container is ejected for-ward from the outer case by the pressure of the explosing charge against the pressure plate. As soon as the outer container is clear of the outer case, the pressure plate and the lid fall clear. The lid acts as a pilot parachute and withdraws the main parachute from the container. The main parachute opens, and, since it so connected by a spring shock absorber to the inner container, it pulls the latter clear of the outer container, which continues to fall, paying out the coiled mine wire inside it as it falls.

Also attached to the outer container is a cord, which pulls out the arming wire of the bomb as the two containers separate. This cord subsequently breaks away to clear the wire which is being paid out. The upper end of the mine wire is attached to the bomb and jerks it clear of its retaining-spring clip in the inner container. The bomb is then sus-pended from the shock absorber by a length of light cord, termed the weak link. This cord is secured to the shock absorber at one end, and at the other to a length of heavy cord leading from the bomb to the 7½-inch parachute carried in the inner container. The heavy cord is thus slack between the knot and the parachute.

When all the mine wire has been paid out, the bottom bundle, containing the 30-inch parachute, is withdrawn from the outer container. The canvas bands which protect the bundle on its way out of the container are then pulled clear by the release cord, and the bottom bundle is left hanging from the wire. This state is accomplished about eight se-conds after separation of the outer container from the rocket.

When the mine wire is struck by an aircraft, the weak link between the bomb and the shock absorber breaks, and the 7½ inch parachute is puled clear of the inner container and springs open. The tautening of the wire also rips the bag of the bottom bundle, and the bottom 30-inch parachute opens. As the aircraft pushes the wire along, the bottom parachute acts as a drogue and drags the wire across the aircraft, pulling the bomb down into contact with it.

The Bomb No. 2 Mk I consists of a light sheet-steel case filled with explosive and con-taining a striker, detonator, and self-destroying assembly. When the arming pin is with-drawn, the detonator is forced by its spring into alignment with the striker. Simultane-ously the delay firing pin on the detonator carrier strikes the cap and a lenght of safety fuse is ignited. When the bomb strikes the aircraft, the striker is forced in and fires the detonator, exploding the bomb instantaneously. If the wire is not struck by the aircraft, the safety fuse will burn through and detonate the bomb after about 95 seconds. Thus the bomb is self-destructive after about 1,250 feet of fall.

Remarks: The round should not be subjected to tempartures in excess of 110° F.