Cluster Projectile 500-lb. No. 4 Mk I (Service)

Description: This cluster is hexagonal in shape, and contains fourteen 30-lb. type "J" incendiaries, in two fagots of seven bombs each. The bombs are placed nose-to-nose and arranged in super-imposed rows of 2, 3, and 2 in each fagot. The bombs are retained in position by the front and rear end plate, the top and bottom beams, the side fairings, tensioning straps, and the retaining bar. The front and rear end plates secure the spring-laoded covers of the bomb parasheet containers. Lateral pins on the retaining bar enga-ges with and hold the tabs of the tensioning straps in position. A shear wire near the end plate acts as a safety device for the retaining bar. To the rear end of the retaining bar is secured a pivoted lever, the lower end of which engages with the piston in the fuze adapter.

The fuze adapter is fixed to the channel plate, which in turn is fastened to the rear end plate. A nut, welded to the center of the rear end plate, receives the tail tie rod to which the tail unit is secured by a tension nut. A nose fairings is secured to the front end plate, and fairings are fitted to the top beam. The fairing adjoining the rear end plate is slotted to receive the fuzing lanyard of the fuze and the safety wire of the tail unit.

Tail Constructio: The Tail Unit No. 44 Mk I is located by two dowel pins and is provi-ded with two inspection windows to ensure correct alignment of the arming fork. A tie rod connects the tail unit to the cluster.

Functioning: On release from the aircraft, the fuze-setting control link withdrawn the safety wire from the tail unit and at the same time, breaks the shear wire of the fuze by means of the fuzing lanyard. The cluster falls normally until the fuze functions. The ex-plosion of the fuze magazine forces the piston forward in its housing to cause a rocking movement of the pivoted lever. The sudden movement of the pivoted lever exerts a pull on the retaining bar to break its shear wire and disengage the lateral pins from the tabs of the tensioning straps. The straps, thus released, fly outwards to release the 14 bombs, which function normally on impact.

Suspension: This cluster projectile is designed to replace the Small Bomb Container as a means of carrying 30-lb. type J incendiaries.

Figure 106 - Cluster Projectile 500-lb. No. 4 Mk I