Patent GB-803906-A (GB)
Title: Improvements relating to means for controlling release of blast gases from armament on aircraft
IPC: B64D7/02
Filed: 1957-01-18
Abstract: 803,906. Mounting guns in engine fairings on aircraft. CHANCE VOUGHT AIRCRAFT Inc. Jan. 18, 1957 [Jan. 20, 1956], No. 1957/57. Class 4. [Also in Group XXI] Means for controlling the fire of and release of blast gases from guns mounted on aircraft or as to prevent the blasts damaging the structure and impairing the operation of the aircraft (see Group XXI, Class 92) include blast gas deflecting means which reduces the severity of individual blasts at each gun location. Considering one side of the aircraft, two guns 49A, 50A, Fig. 2, are mounted in the fuselage 22 just above the left hand engine air duct 25A. Projectiles from the gun 49A pass through an elongated blast deflection chamber 52, Figs. 2, 3, with gas exit openings 31A, 32A, 33A and emerge from the airframe through a blast tube 37A which opens to atmosphere at the air duct lip 26. Similar arrangements are provided for the gun 50A and the two guns on the other side of the aircraft. At its inlet the air duct 25A has an inboard wall 40 separating the air duct 25A from the boundary layer air duct 28 which is located between the wall 40 and the fuselage side panel 27. Around the forward portion, the air duct 25A is covered by a skin 42 which fairs the duct to the fuselage and extends concentrically around the duct outboard wall 41 it being spaced therefrom by formers 43-46. Between the fairing skin 42 and the wall 41 lies the forward end of the gun compartment 47 whose aft end extends into the fuselage 22. At the forward edge of the duct lip 26, the wall 41 and skin 42 coalesce and thus close the forward end of the gun compartment 47. The gas deflection chamber 52, which is rigidly mounted in the compartment 47 receives the muzzle end of the gun 49A and has a pair of spaced walls 54, 55 whose inner edges are connected by a third wall 56 and whose outer edges are flanged and secured to the edges of cut-outs (not shown) made in the skin 42. The chamber 52 is also provided with forward and aft walls 57, 58. Cross pieces 63, 64 extending between the flanged outer edges 59, 60 define an aft opening 31A, a middle opening 32A and a forward opening 33A, through which some of the blast gases are deflected by plates 101, 107, 108, the remainder of the gases passing through an opening 74 into the blast tube 37A. The blast tube 37A comprises a cylindrical portion 133, a trough portion 134, a mouth portion 135, the latter being crossed by a pair of deflector plates 136, 137, and upper and lower fairing portions 138, 139. The mouth 135 is flared and has an oval opening 141 lying flush with the contour of the duct fairing skin 42 and vents the trough 134 and portion 133 to the atmosphere above and outboard of the air duct 25A. The flared shape of the mouth 135 is achieved by a series of bevelled surfaces 146, 147, 148 which induce the blast gases to flow radially away from the original flow axis and upwardly, outwardly and rearwardly away from the air duct inlet opening and the aircraft. The forward end of the gun barrel 49A is rigidly secured in the rear wall 58 of the chamber 52 by means of an adapter tube 76 and an adjustable seal assembly consisting of an outer eccentric 86, inner eccentric 87, ring 88 and circular clamp 89. This arrangement permits repositioning of the gun barrel relative to the aircraft centre line.