Cluster Projectile 500-lb. No. 14 Mk I (Service)

Description: The cluster comprises two fagots of 53 bombs each. The bombs in the two fagots are arranged nose-to-tail, and with their safety plungers inwards so that they are all depressed. The bombs are held in place by a front end plate and a rear end plate, a top beam and a bottom beam, four wooden slats, tensioning starps, and a retai-ning bar having lateral pins which engage tabs on the tensioning straps. A shear wire passes through a bridge and the retaining bar at a position near the rear end plate. A channel, secured to the rear end plate, supports a fuze adapter, the outer end of which is closed by a transit plug fitted with a leather washer. Inside the adapter is a piston through which a pin is arranged to engage the lower end of a pivoted lever. The fuze adapter and the piston are slotted to receive the lever. The upper end of the lever is forked and is connected to the retaining bar. The rear end plate has to dowels for locat-ing the tail in position, and a nut welded to the center of the rear end plate to receive one end of a tail tie rod when the tail unit is fitted to the cluster. A nose cover is fitted to the front end plate to decrease the drag of the cluster.

Tail Construction: The Tail Unit No. 42 Mk I is a shortened drum-type tail, having a tail cone to which a tail ring is secured by fins. At the base of the tail cone are two holes to fit over the dowels on the rear end plate of the cluster. The tail unit is fitted with a bearing for an arming spindle, so that, if it should ever be required to fuze the cluster with an air armed fuze, a suitable arming spindle with an arming vane could be readily fitted. Also, to provide against this contingency, a bracket to receive a safety wire is welded to the tail cone and a hole passes through a projection on the support for the arming-spindle bearings. A tie rod passes through the center of the tail, and one end of the rod is screw threaded to go into the central nut of the rear end plate. Two win-dows, one of which is open, are provided in the tail cone. The open window is provided so that when the cluster is prepared for use, the fuzing link, connected to the pull per-cussion mechanism of the Fuze No. 42 Mk IV, can be passed through it and connected to the fuzing unit of the bomb carrier.

Functioning: When a cluster is released from an aircraft, the fuze functions, and after a period of delay during which the cluster projectile falls freely, the fuze magazine charge is fired. The products of combustion of the magazine charge force the piston in the fuze adapter against the lower end of the pivoted lever, which is thus rocked about its pivot and exerts a pull on the retaining bar of the cluster. This causes the retaining bar to break its shear wire, and to move so that the pins on the bar disengage the tabs on the tensioning straps. The straps then fly outwards and the cluster disintegrates, the component parts falling away separately. The individual 4-lb. bombs function on impact.

Suspension: A British type suspension lug is fitted to the top beam, and tapped holes in the beam are provided for fitting American type lugs.

Figure 110 - Cluster Projectile 500-lb. No. 14 Mk I