Aparatus A.D. Type L Mks I, IA, II, and IIA (Service)

Canister length

Canister diameter

Motor length

Motor diameter

Use: The purpose of the Type L apparatus is to lay a curtain of aerial mines in the path of low-level or dive-bombing aircraft.

Description: The Canister Mk I consists of a conical upper container, which is con-nected to the tail of a 2-inch rocket motor by a short rod and a stirrup. In the upper container are a parachute to bring down the spent motor, etc., the main support para-chute, a bomb steady parachute, and the bomb. These items are all held in position by three retraining cords, which are controlled by an explosive link.

The swivel on the lower end of the bomb is connected to the top end of a 1,000-ft. coil of steel piano wire, which is contained in the lower container. The wire from the bomb passes to the top of the coil through a slot cut in the central tube. The central tube is provided to aid in unspooling the wire and avoid failures due to kinking. The lower end of the 1,000-ft. coil of wire passes back through the slot in the central tube and is connected to a long, light shock absorber, whose lower end is attached to the drag pa-rachute assembly. This latter consists of a 32-in. drag parachute housed in a bag and prevented from opening on the initial jerk at pick-up by four retaining cords controlled by an explosive link. The junction between the upper and lower containers is effected by crimping parts of the base of the upper container lightly over the top of the lower con-tainer.

The electric leads for igniting the electric delay fuzes extend from the base of the lower container and terminate in a two-pinned plug which fits into a socket on the pro-jector.

The Bomb H.E., A.A.D., No. 8 Mk I consists of a light sheet-steel cylinder filled with explosive. A detonator is held in a shutter which is normally kept out of alignment with the striker by a clock spring. An arming vane is attached to the outside of the bomb cas-ing, and this vane, by means of a pinion wheel, is enabled to move the shutter suffici-ently to align the detonator with the striker.

The Tail, Propelling, 2-in., Mks IVB and VB consists of a slightly modified 2-inch stan-dard rocket motor. A closing plug is placed in the shell ring, and the electric leads termi-nate in a two-pin plug, which engages a socket on the projector. The propelling unit is connected to the canister assembly by a 12-inch steel stirrup and a steel connecting rod 18 inches long. A quick fastening bolt is provided in the top of the canister for rapid con-nection to the connecting rod. The proposed new nomenclature for the motor is Motor, Rocket, 2-in., No. 3 Mks I and II.

Operation: When the projector switch is closed, the rocket itself and the delay fuzes on the upper and lower explosive links are ignited simultaneously. The rocket motor tows the top container into the air, and the wire is unspooled from the lower container, which remains fixed on the projector. At the end of unspooling, the drag parachute assembly is picked up, the snatch tension being kept within safe limits by the long shock absorber. The upper and lower explosive links are timed to operate when the container has reached a height of about 2,000 feet.

On operation of the explosive link in the top container, the bomb and parachutes are released and pulled out of the container. Ejection of the rocket-support parachute is facilitated by a very weak cord connection between the rocket-support parachute and the main parachute. The operation of the lower explosive link removes the constraint from the drag parachute and leaves the parachute free to open when a plane makes contact with the wire.

When a plane hits the wire, the drag parachute opens, and the weak link securing the 6-ft. support parachute will part. The bomb is pulled downwards onto the wing of the plane by the drag parachute. When the bomb strikes the aircraft, the striker is forced downwards by the universal striker ring, firing the detonator.

Remarks: This rocket should not be fired outside of the temperature range of 0 -120° F.

The Mk II canister is identical to the Mk I, except that no shock absorber is fitted, one side of the slot in the central tube is slightly flared to assist unspooling, and the length of the piano wire coil is 1,500 ft. instead of 1,000 ft.