British Bomb, 4.5 inch Photoflash, Heavy




The Photoflash Bombs Mk I and Mk II are similarly constructed, the only difference being that the Mk II has narrower tail fins. Each flash has a tubular body, closed at the tai] by a closing dome and at the nose by a front diaphragm having a bush into which is screwed the nose fuze. The four tail fins are located at the after end. A quantity of flash composition is contained in the body between a front and rear diaphragm. The filling hole is closed by a press-cap and overseal. A central tube, closed at each end, extends between the front and rear diaphragms and is filled with gunpowder. A socket secured to the front diaphragm houses a perforated disc, and a muslin disc, which closes the nose end of the central tube. The perforated disc is held in position by a socket plug having a flash hole covered by a disc, which, in earlier issues, is made of brass, but in later issues is paper.

The bomb is suspended by means of a suspension band to which are secured two suspension lugs, one for attaching to a Light Series bomb carrier, and the other for attaching to a Universal bomb carrier.

These flash bombs are intended to provide illumination for night photography, and when activated they explode with a loud report and a vivid white flash. It is important to distinguish between flares and photoflash bombs. They may be distinguished by the following characteristics. FLASH is stencilled on the nose of all photoflash bombs, and the tail of the bomb is red. Eight rivets are visible around the body at the junction of the red and black parts of the bomb. On removal of the tail dome of a flash bomb, there is no parachute or shackle visible.

Externally, the 4.5 inch Heavy Photoflash Bomb is the same as the ordinary 4.5 inch photoflash. Internally, the construction is slightly modified, as the rear diaphragm is moved to a position nearer the closing dome, consequently increasing the length of the central tube. A retaining diaphragm is positioned in the body 5 1/2 inches from the front diaphragm. A cast iron weight is located between the front and retaining diaphragms, the flash composition being housed between the rear and retaining diaphragms. The fuze is a US Mechanical Time Fuze M111, which has a fuze adapter in order to fit it into the British bomb. When it is loaded, the arming wire is fitted through the second hole in the arming pin and passes through the arming vane lock. The delay may be from 5 seconds to 93 seconds. The heavy bomb weighs 40 lb.

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OP 1665, British Explosive Ordnance (1946)