Patent GB-645323-A (GB)
Title: Improvements relating to pilot seat ejectors for aircraft
IPC: B64D25/10
Filed: 1948-07-26
Abstract: 645,323. Seat ejection apparatus for aircraft. M. L. AVIATION CO., Ltd., and LOBELLE, M. J. O. July 26, 1948, No. 19952. [Class 4] [Also in Group XXI] A seat ejection apparatus for aircraft comprises telescopic ejection cylinders operatively interposed between the seat and the aircraft, an exhaust tube through which the gases generated by the explosive charge can be dissipated in case of inadvertent firing, and a movable breech adapted to hold the explosive charge, the movable breech being normally in communication with the exhaust tube but movable into communication with the ejection cylinders by proper operation of the ejection apparatus. The seat 13 is mounted beneath a displaceable canopy 11 and comprises side channels 17 provided with rollers 23, 24 respectively arranged to slide in vertically overlapping I-section guide rails 18, 19 secured to the aircraft structure. The pilot 12 is provided with a protective apron 26 pivotally attached to the head rest 27 by arms 28, fast with one of which is an arm 32 connected by a link 33 and a bellcrank 34 with a rod 36. The upper end of the rod 36 is pivotally attached to one end of a lever 37 pivoted at 92 to a plate 61 forming one of a pair of cheekplates fast with a bearing block 58 rigidly connected to the channels 17. The cheek plates are connected also to the head 43 of the outer element 42 of a pair of telescopic cylinders, the lower end of the cylinder 42 being provided with a flange 44 engaged by a pair of claws 46 mounted on a bracket 39 secured to the rails 18. The claws 46 are secured together by a frangible pin 48 which is sheared when the claws are separated by a wedge 51 forced downwards by,the action of the explosive charge acting on a piston 49 mounted within the inner telescopic cylinder 38 which is mounted at its lower end on the bracket 39. The explosive charge is carried in a breech tube 54 pivotally supported in bearings 57 on the block 58 so that it may be aligned with the cylinders 42, 38 or an offset exhaust tube 68 which communicates at its lower end with atmosphere so that if the cartridge is inadvertently fired the gases generated by the explosive charge may be dissipated through the tube 68 without ejecting the seat. The breech tube is rocked about the pivot 57 by a pair of toggle links (Fig. 6, not shown), actuated by a slide bar retained in a slot 83 in the plate 61 by a bracket 84 connected to the lower end of a rod 87 which is guided at its upper end by a cleat 88 attached to the block 58. A pin 89, secured to the rod 87, works in a slot 91 at the free end of the lever 37. The cartridge firing mechanism comprises a striker arm 107 urged downwards by a leaf-spring 112 and tripped by a lever 121 rocked upwards by the upper extremity of the rod 87. To release the seat, after the cockpit cover has been released, the pilot pulls the protective screen down which causes the lever 37 first to rock the breech tube 54 from the normal position in line with the exhaust tube 68 to the position where it is in line with the telescopic cylinders, when further movement of the lever 37 trips the lever 121 to fire the cartridge. A visual indicator is provided to show if the breech is loaded and safety devices are provided to ensure that the breech locking pin is not inserted if the lever 121 is not cocked or that the ejection mechanism will not operate unless the seat is in the correct position for ejection. Specifications 590,253 and 624,143 are referred to.