AIRCRAFT BOMBS.212. Bombs at present in use can be divided into 7 groups:-(i) A.P. (Armour-Piercing) and S.A.P. (Semi-Armour-Piercing)(ii) G.P. (General Purpose) and M.C. (Medium Capacity) }H.E. Bombs(iii) A/S (Anti-Submarine). }H.E. Bombs(iv) Anti-personnel. }H.E. Bombs(v) Incendiary.(vi) Practice.(vii) Drill.The main filling of H.E. bombs is detonated by similar means to those employed in shell, i.e., by an exploder which in turn is ignited by a detonator. The detonator is initiated by means of a pistol. In some bombs the detonator and pistol mechanism are combined in one unit termed a fuze. In either case when a bomb is 70 fitted for service it is said to be fuzed. Mechanical arrangements in the pistol or fuze allow the bomb to be dropped "Safe" or "Live" as desired. When dropped live, the fuze cannot function until the bomb has travelled through the air far enough to " arm " the fuze. This travel is called the " arming distance."(i) A.P. Bombs-2,000 lb.These bombs are designed for use against heavily armoured targets and are made of steel. They contain a comparatively small charge in relation to the total weight. Detonation is initiated by a fuze in the tail.S.A.P. Bombs-500 lb. and 250 lb.These bombs are designed for use' against lightly armoured targets. They are made of steel and contain a comparatively small charge. Earlier types are fitted with a tail fuze, and the latest type with a tail pistol and detonator, giving the required delay.(ii) G.P. 250 lb. and M.C. Bombs, 500 lb.These bombs, as the name implies, are used to attack a variety of targets. They rely chiefly on blast effect to cause damage and have a relatively large charge. They are fitted for nose (instantaneous) or tail (delay) fuzing, and use a pistol and detonator in both cases.(iii) A/S Bombs, 100 lb.These bombs are used against submarines, and also against certain targets where a large blast effect is required. They have a relatively large charge, and are fitted for a tail pistol and detonator. (Earlier types were fitted for a nose fuze.)(iv) Anti-Personnel Bombs, 40 lb. G.P. and 20 lb. Fragmentation.These bombs are designed to give a large number of small fragments on bursting and are fitted with a nose pistol and detonator only. Otherwise they are generally similar to the larger G.P. bombs.(v) Incendiary Bombs, 25 lb. and 30 lb.The 25 lb. incendiary bomb consists of a metal case containing seven magnesium and thermite firepots which are ejected at 4-second intervals by means of small explosive charges. The 30 lb. incendiary bomb contains an incendiary filling which is ignited and spread by means of an exploder contained in a nose fuze.(vi) Practice Bombs. 8 1/2 lb., 10 lb. and 11 1/2 lb.These bombs contain either a smoke flame or a flash composition; smoke for day and flame or flash for night use respectively. On impact a small detonator-burster is ignited by means of a pistol which is an integral part of the bomb.(vii) Drill Bombs.These may be of any of the above types differing only in that the filling is inert.Safety Arrangements.213. Bomb pistols and fuzes are fitted with safety arrangements to prevent detonation of a bomb before it is required for use or in the event of a crash or premature release. The safety arrangements take the following forms:- 71 (i) Safety Pillar: This is fitted to fuzes to prevent the rotation of the arming vanes (see below) during transit and is removed only after the bomb is loaded on to the aircraft.(ii) Safety Clips: These are fitted to pistols and fuzes to prevent the rotation of the arming vanes whilst attached to the aircraft in the air. They are removed when the bomb is released " live," or remain on the bomb if it is dropped " safe."(iii) Arming Vanes: These are fitted to fuzes and pistols and rotate as the bomb falls through the air if the safety clip has been removed. In the case of fuzes they drive a system of gears which renders the fuze " live " requiring only the shock of impact to fire the detonators. In the case of pistols they unscrew an arming nut or cap from the striker which is then held by a creep spring or shear wire only.Note. In the case of tail pistols the arming vane is fitted on the bomb tail and connected to the pistol by means of a spindle.Supply and Fuzing.214. Bombs of 100 lb. and above are supplied unboxed, their tail units and nose pistols being in separate containers. Tail pistols are usually supplied in position in the bomb. Smaller bombs are supplied boxed with pistols in position. Detonators and fuzes are supplied in separate boxes.Fuzing is carried out in accordance with N.M. and E.R. Article 249.Markings. Plate 20.215. Stencil markings on bombs give the following information:-(i) Nomenclature and mark.(ii) The monogram of filling station or trade mark of filling contractor.(iii) The date of filling.(iv) The lot number of filling.Coloured markings are as follows:-(i) H.E. bombs are coloured green (old supply were yellow).(ii) A red band round the nose denotes Filled.(iii) A white band contiguous to the red band denotes S.A.P.(iv) A white band either side of the red band denotes A.P.(v) A plain green band denotes T.N.T. filling. T.N.T. is stencilled on or near the band.(vi) A plain green band with a numeral above and a fraction below indicates an amatol filling of low grade.(vii) A criss-cross green band with a fraction below denotes an amatol filling of high grade.(viii) Incendiary bombs are painted dull red.(ix) Practice bombs are painted white. Two green bands on the tail denote "filled with smoke composition "; two black bands on the tail and a red band on the body denote" filled with flash composition."(x) Drill bombs are painted black with yellow band.Note. In (v) and (vi), new supply, the green band is of a lighter shade than the body colour.