USE:

This rocket is designed to erect vertically over a ship a lethal wire in the path of low-level or dive-bombing aircraft. The wire acts both to bring down the aircraft if it strikes the wire and as a visible deterent to force the aircraft to abandon the attack.

DESCRIPTION:

Head Canister: This is a light cylindrical metal container, into which is packet a 62 inch parachute (called the 'top parachute'), the cords of which are firmly secured to the base of the head canister. A thermal fuze is fitted into the head canister and con-sists of a pellet of LDNR, a length of safety fuse, and 100 grans of G.12 gunpowder, which acts as an ejection charge.

Tails Propelling 2", Mks IVA & VA: The propelling unit consists of a standard 2 inch rocket motor, with a rigid stirrup welded to the after end. No fins are fitetd to the mo-tor. Contained within the motor body is a tubular cordite grain, into the head of which is fitted an electrical igniter. The after end of the motor is sealed off by a light metal closing disc, through which pass the ends of the igniter leads terminating in a two-pin plug.

Main Container: This is a cylindrical shaped metal container about 14 inches in dia-meter, with a removable lid. Inside the container are two smaller concentric tubes, the outer which is cone-shaped, while the inner is cylindrical. Also encased within the main container are 825 feet of wire, a fabric bag into which is packed a 62 inch diameter parachute (called the 'lower parachute'), and a 20 inch diameter parachute (called the 'trail parachute'). The wire is coiled down between the cone shaped cylinder and the main container, and swivel are attached to the top´and bottom ends of the wire. The bottom swivel is shackled to the ring at the foot of the cords of the lower parachute, the ring just protruding through the fabric bag. Cords which keep the bag closed are connected to the trail parachute by a weak cord connection and a rip cord. The tail parachute and fabric bag are packed into the small central cylinder, the swivel passing through a special slot, and the cylinder is then sealed with a light metal lid.

OPERATION:

The rocket is fired when the plane is within about 800 yards of the ship. The wire is fully run out 3-1/2 seconds after firing and pulls the lower parachute bundle and the trail parachute up out of the inner cylinder, the lid of which is ripped off by the bottom swivel as it is pulled up. Meanwhile the heat from the burning cordite grain ignites the LDNR pellet in the thermal fuze, and this in turn ignites the safety fuse. The safety fuse burns for about 6-1/2 seconds and then initiates the gunpowder ejection charge, blow-ing off the top part of the head canister and allowing the top parachute to open. This occurs at an altitude of about 1100 feet. The lower parachute, still wrapped in its bag, is suspended at the bottom of the wire, and the trail parachute (now open) is attached to the bundle by the weak cord connection and the rip cord. After the top parachute opens, the wire begins to fall at about 42 ft/sec, and 12 seconds after firing, the bot-tom parachute enters the water. As soon as this occurs, the wire ceases to be lethal, but it remains a visible deterent for an additional 12 seconds, by which time the top parachute has fallen to an ineffective height.

REMARKS:

(1) The round must not be fired outside of the temperature range of 0-120° F., ex-cept motors marked "S.U./K." which may be fired with the range of -5 to 130° F.

(2) The Mk I Apparatus differs from the Mk II in that the ceilling height of the rocket is 800 ft., and the wire is only 600 feet long.

(3) Proposed new nomenclature for the rocket motors is "Motor, Rocket, 2", No. 2 Mk I & II".