CONSTRUCTION. The sheet steel, bomb-shaped body is supported internally by a series of eight annular strengthening bulkheads. Welded to the after end of the body is a tail cone which terminates in a short parallel sided tube over which is assembled an adapter designed to accept the aluminum body of the lamp unit. Four stabilizing fins are welded to the tail cone and strengthened by metal struts. The nose portion of the bomb body is welded to the parallel-sided portion of the body and terminates in an annular flange to which the solid steel nose plug is bolted through a castellated collar. The rear face of the nose plug has been recessed to form a housing approximately 1 1/2 inches deep for the battery unit which is assembled inside a central tube of drawn steel 18 1/2 inches long and 4 1/8 inches internal diameter. The battery unit consists of a series of small dry cells contained within an insulate cylinder. (See fig. 89).

Provision is made for six cells in each layer, the cells being arranged around a central tube through which a retaining bolt passes to secure it to the nose plug. The rear end of this tube is closed by means of a closing cap to which an annular brass contact disc is secured and which is held in place by means of a washer and nut. A contact is located in the tail adapter by a grub screw and slot arrangement. Passing through the contact bush and screwing into the tail adapter is a lamp unit which consists of a cast aluminum body with an insulated contact rod secured through the base of the casting by two grub screws. At the base of the rod, a spring switch is mounted with leads to the battery unit and the lamp unit.

Positioned between the two arms of the spring switch is an insulated interia bolt which breaks the contact until closed on impact. The lamp unit is spring mounted to protect it from shock and covered by a lucite type dome. When the marker is released from the aircraft, the inertia bolt is positioned between the plates of the spring switch and one side of the circuit between the lamp and the batterie is broken. On impact, the inertia bolt is forced out of position and the circuit between the lamp and battery is completed. As the batteries fill, only a portion of the bomb body and all joints are made tight by rub-ber washers, the marker floats on the surface of the water, and it is assumed, provides a recognition or bearing point for aircraft.

Figure 89 – Sea Marker Bomb