ROCKETS USED IN

FUNCTIONING

ARMED CONDITION

ARMING TIME

MAX. BODY DIAMETER

OVERALL LENGTH

VANE SPAN

COLOR

DESCRIPTION:

This fuze consists of the No. 721 Mk III fuze (See page 93) modified for safe carri-age on aircraft. These modifications consist of the removal of the safety cap and safe-ty clip from the standard No. 721 Mk III fuze and the addition of two semi-discs fitted with vanes, a circlip, a setback collar, an inner sleeve, a spring, and spring retaining washer.

In the unarmed position, the two semi-discs are inserted between the pressure plate of the striker and the head of the fuze body, preventing the striker from moving down-wards. The semi-discs are retained by a circlip which fits into an annular groove machi-ned around the top of the two discs. Rotation of the vanes and the semi-discs is pre-vented by two grooves on the top edge of the setback collar in which the vanes en-gage. A Pin loacted inside the setback collar rides in a slot cut in the inner sleeve, pre-venting the collar from rotating. The inner sleeve, in turn, is prevented from rotating by its engagement with the protruding end of the shear wire of the fuze. The setback col-lar is held in the raised position by the inertia spring, which is retained by the spring re-taining washer.

OPERATION:

When the rocket is projected from the aircraft, the setback collar rides down against the action of the inertia spring. The semi-discs are thus disengaged from the setback collar, and are free to be rotated by the attached vanes. When the rotational speed of the semi-discs reaches about 300 rpm the centrifugal force thus created overcomes the restraint of the circlip, and the two semi-discs fly free of the fuze.

Impact with the target causes the pressure plate to force the striker through the aluminum shear wire into the detonator, firing the magazine and exploding the shell.