Patent GB-640520-A (GB)
Title: An ejection seat for aircraft
IPC: B64D25/10
Filed: 1947-07-10
Abstract: 640,520. Aircraft pilot escape apparatus. MARTIN, J., and MARTIN-BAKER AIR. CRAFT CO., Ltd. July 10, 1947, Nos. 18251 and 24622. [Class 4] An ejection seat for aeroplanes of the type described in Specification 583,257 comprises in combination a seat, a frame on which the seat is slidably mounted.for positional adjustment, means for adjusting the seat on its frame, a guide adapted to be fixed in the aeroplane so as to be directed toward an outlet from which the seat may be ejected, means slidably supporting the seat frame on the fixed guide, an ejection gun operating between the seat frame and a fixed part of the aeroplane to eject the seat and its frame along the fixed guide and means for operating and detachably securing the ejection gun to the seat frame and to the fixed guide. The seat 1 is mounted by its back 2 on a seat frame 3 which is provided with rollers 4 adapted to engage in channels formed on opposed sides of a guide fixed to the aircraft structure. The ejection gun, which is detachably secured to a transverse beam 11 on the upper rear face of the frame 3 and to the lower end of the guide, is fired automatically by a face protecting apron housed behind the head-rest 13 in the upper part of a drogue parachute container 12 and extended by a handle 14. The drogue parachute is ejected by a mechanism in accordance with Specification 616,238. The harness of the occupant of the seat is secured to eyes 21 attached to the ends of cables wound on a spring-controlled drum mounted in the lower part of the compartment 12. The drum is provided with a releasable ratchet mechanism operated by a cable control device and a lever attached to one seat arm 23, whereby the occupant may be allowed a restricted freedom of movement. The top of the seat back 2 is slidably pivoted at 49 to seat frame members 32, Fig. 14, rigidly connected at their lower ends by a tube 38 within which is housed a rotatable torque tube 44 provided at one end with a seat raising hand lever 47 and at points intermediate its ends with arms 45, to which are pivoted brackets 43 secured to the underside of the seat pan. The arms 45 extend rearwardly and are provided with manually controlled catches 53 to engage holes 54 formed in quadrants 52, mounted on the members 32, to provide positional adjustment. The weight of the occupant is balanced by compression springs 66 housed in telescopic tubes secured between the seat back 2 and the frame members 32. Footrests 22 which normally rest on the cockpit floor are suspended beneath the front of the seat to receive the feet of the occupant in accordance with Specification 607,527. Each footrest is attached to the forward end of an arm 70 pivotally secured to the torque tube 44 and is raised with the seat by a link 73, slidable in a trunnion 74 to enable the seat to be fully lowered when the foot-rests are in contact with the floor. The first Provisional Specification describes an arrangement of telescopic footrests which incorporate springs to counterbalance the weight of the occupant. The ejection gun 7 which is housed within the hollow guide and fired by a mechanism 15 in accordance with Specification 601,718 comprises a cylinder 8 having a part-spherical seating 81 co-operating with a seating 82 on a block 10 attached to the lower end of the guide, the body 80 of the cylinder 8 being releasably secured to the block 10 by a spring-loaded releasable plunger 83. The upper end of the piston 9 is releasably secured in a similar manner to the aforementioned transverse beam 11. The piston 9 is releasably secured to the lower end of the cylinder 8 by spring fingers 113 attached to the body 80 of the cylinder and urged into engagement with an internal collar 111 on the piston by the upper rim of a piston 114 urged upwards by a spring 116 and automatically forced downwards to release the fingers 113 and piston 9 by gas pressure when the ejector cartridge is fired.