GB590253A - Improvements relating to safety devices for aircraft pilots - Google Patents

Abstract

590,253. Safety devices for aircraft pilots. MALCOLM, Ltd., R., and LOBELLE, M. J. O. April 12, 1945, Nos. 9153 and 32323. [Class 4] A safety device for an aircraft pilot comprises a pilot's seat mounted to slide upwardly on guide members in the aircraft, an ejecting device adapted to hold an explosive charge and connected to the seat, and a locking device which normally holds the seat in its working position but is released automatically by the gas pressure resulting from the explosion of the charge. As shown, Fig. 1, the seat 10, 11 is carried by a metal frame supporting a cross-bar 13 over which the pilot can tuck the heels of his shoes when about to operate the ejector, the frame being fitted with brackets 19, 22 and 24 in which are mounted rollers 18, 21 and 23 engaging channelled guide rails 14, 15 and 16 secured to the aircraft cabin structure. The ejector mechanism comprises telescopic cylinders, the inner cylinder being carried by a bridge 32 mounted on a cross member 30, and the head 34 of the outer cylinder 33 being connected by links 35 and 36 to frame members 37 of the seat back. In one form, Fig. 6, the inner cylinder 46 has a screwed base portion 47 mounted on a bracket 40 secured to the bridge 32. Claws 41, pivoted to the bracket 40 and engaging a ferrule 45 screwed to the lower end of cylinder 33, normally hold the seat in its working position and are connected together by lugs 44 engaging a shear pin 43 of aluminium or brass. The upper end of the cylinder 33 contains a cartridge 54 which may be fired by an electrically-operated striker 58 or by ignition leads 59 (see Fig. 8, not shown). In firing the cartridge, the gas pressure rises, the cylinder and seat are moved upwardly on the guide rails and ejected from the cockpit. The piston 48 is fitted with a flap valve 52 which is normally open to allow pressures inside and outside the cylinder to equalize during gradual changes of atmospheric pressure, but which is closed by the gas pressure as soon as the cartridge is fired. In a second form, Fig. 7, an intermediate cylinder 62 is fitted between the cylinders 46 and 33 to allow the gases produced by firing of the cartridge to act over a longer period. A thin metal thimble 64 is mounted in the cap-shaped end of the cylinder 62 to form a gas seal, and the ferrule 45 carries a metal ring 66 which absorbs shock by crushing when the cylinder 33 picks up the cylinder 62. The bracket 40 may be mounted on the bridge 32 by means of a hand-operated screw jack so that the height of the seat may be adjusted (see Fig. 9, not shown). The pilot's parachute is arranged to open automatically after ejection. The pilot may be strapped to the seat so as to descend with it, or the opening of the parachute may free the pilot from the seat so that it falls separately. Specifications 399.332 and 583.257 are referred to.