Patent GB-743776-A (GB)
Title: Improvements relating to escape apparatus for airmen
Inventor: LOBELLE MARCEL JULES ODILON
IPC: B64C1/32
Filed: 1952-07-07
Abstract: 743,776. Jettisonable hoods for aircraft. M. L. AVIATION CO., Ltd. Oct. 7, 1953 [July 7, 1952], No. 17043/52. Class 4. In jettison mechanism for an aircraft canopy in which the canopy is lifted with the aid of fluid pressure acting in a cylinder, release mechanism, normally manually operated, is operated automatically by the fluid pressure in an emergency. The canopy comprises a main beam 1 hinged to the aircraft structure about a pin 2 at the top of its rear edge and formed with a heel portion 3 having a pin 7 engaged by a retaining pair of claws 5, 6 on one arm 4 of a toggle linkage. The other arm 9 of the linkage is pivoted to the aircraft at 10 and to the arm 4 by a pivot 8 which is engaged by the bifurcated end of an auxiliary piston rod 39 of a gun 29. Intermediate its ends the arm 9 has a pin 16 engaged by a spring jack 15, the action of which assists in opening the canopy when the gun 29 thrusts on the pivot 8. The canopy is held closed by catches (not shown) on its forward edge and in normal release operation these catches are released separately and the claws 5, 6 holding the pin 3 and retaining pawls 61 for the hinge pins 2 are released manually by rotation of a shaft 102 coupled to the firing mechanism for an explosive cartridge in the gun 29. The shaft 102 carries fingers 100, 101, the former co-operating with a lever 103 pivoted at 104 and the latter with an axially movable rod 46. Anti-clockwise rotation of the shaft causes lever 103 to bear against a roller 105 on a link 72 pivoted to a three-armed lever 70, rotation of which disengages one arm 69. from the tail of a lever 66 carrying a roller 65 thus permitting anti-clockwise rotation, under the action of a spring 64, of the pawl 61 which holds each pin 2 in its hinge box 60. The other arm 85 of the lever 70 carries a roller 86 which is in a slot 87 on a hooked member 88 so that, as described later, when the canopy is released automatically, movement of the member 88 brings it into contact with a pin 90 on the heel portion 3 so that initial opening movement of the canopy releases the pins 2. Anti-clockwise movement of finger 100 causes the rod 46 to rock a pivoted member 49, normally urged to a locking position by a spring 53, to free the claws 5, 6 from the pins 3. In emergency all of the foregoing operations are effected automatically. The gun 29 houses a sleeve 41 which is extended by the explosive charge, and which accommodates the auxiliary piston 39. When the gun is fired automatically a plate 38 on the end of sleeve 41 engages the tail end of a lever 26, which, through a link 18, co-operating levers 20, 22 and a rod 17 releases the front catches. (A rod 28 is provided for emergency manual actua. tion from outside the aircraft.) The plate 38 engages also the tail of a lever 76 pivotally connected at 75 to the lever 72 so that extension of the gun releases the pawls 61 from the hinge pins 2. An extension 45 on the plate 38 contacts the end of the rod 46 to release the claws 5, 6 in the manner previously described. When the release operations (manual or automatic) are completed continued extension of the gun causes the sleeve 41 to compress a spring acting on the end of the piston rod 39 which thrusts on the pin 8 and, with the assistance of the spring jack 15, causes the canopy to rotate upwardly and rearwardly until the pins 2 become fully disengaged from the hinge boxes 6. In order to permit servicing to be carried out the fingers 100, 101 may be operated independently of the gun firing mechanism to release the canopy.