Patent GB-738046-A (GB)
Title: Automatic parachute release coupling
IPC: B64D17/38
Filed: 1953-04-27
Abstract: 738,046. Parachutes. LEMOIGNE, P. M. April 27, 1953 [May 5, 1952; April 15, 1953], No. 11605/53. Class 4. [Also in Groups XXI and XXXII] A parachute release mechanism for loads dropped from aircraft comprises hooks 1 with their ends engaged during descent in a suspension and locking member 2 having an eyelet 3 secured to the load. The hooks are mounted on pivots 4 carried by an internally threaded sleeve 5 into which is screwed a rod 6 having a piston head 7 slidable in a cylinder 8. The cylinder 8 which is closed by a plug 70 is filled with a liquid such as oil which, as the piston moves, passes from one end of the cylinder to the other through a passage 9, this arrangement constituting a dash-pot to brake the displacement of the piston. The cylinder 8 is secured to a casing 11 having an eyelet 12 for attachment of a parachute or parachutes. The passage 9 is adjusted by movement of a frusto-conical needle 13, by means of a setting-screw 14 having a graduated head 15. The sleeve 5, through which passes a pin 32 to hold the rod 6, has one or more lugs 16 each supporting a pin 17 passing through a partition 19. Engaging the pin 17 is a rod 21 which has at one end a ring 20 locked against the partition and at the other end a ring 22 guided in a tube 23. When the pin 17 is freed from the rod 21, a spring 24 bearing against the ring 22 urges it upwards to actuate the trigger control 50 of a landing parachute. The position of the pin 17 determines the point of the stroke of piston 7 at which the landing parachute is triggered and this position is adjusted by moving a knurled screw-head 25 along a graduated scale 26. Springs 28 surrounding rods 29 and attached to the hooks bear against the partition 19. Before jettisoning the load a string 27 connecting the partition to a lug 16 prevents expansion of the springs 28. After the load is dropped, the opening of the parachute attached to eyelet 12 causes rupture of the string 27. The opposing pulls of the parachute and the load cause the piston to move downwardly with the consequent escape of fluid upwards through the passage 9, the rate of flow being determined by the setting of'the screw-head 15. Thus, after a predetermined time, the pin 17 is pulled out of the tube 23 and the landing parachute is triggered. When several landing parachutes are used the respective pins 17 may be set to give simultaneous openings of the parachutes or to cause the parachutes to open successively. The positions of the pins may also be adjusted to allow for differences between the actual load and the calibrated load as shown by the head 15. When the parachutes open the springs 28 urge the hooks 1 together to prevent the load from escaping until a predetermined additional displacement of piston 7 takes place, when the springs urge the hooks apart. The suspension member 2 is not released from the hooks until the load is grounded. In Fig. 4, the hooks 1 are shown mounted between parallel plates 43 having notches 54 to receive the suspension member 2 in position for engagement with the hooks. Leaf springs 34 urge the hooks apart. During the initial descent the hooks are positively locked by a rod 36 fast with the piston 7 of a dash-pot 8. Calibrated passages 47 allow the passage of fluid through the piston, which is urged upwardly by a spring 38. Before dropping, a rod 39 urged against the piston by a spring 40 holds the spring 38 in compression. The rod 39 is preferably locked prior to dropping by a cord 41. A ring 12a is used to attach the descent parachute. The end of the rod 36 may ,be shaped to engage inclined surfaces 46 on the hooks and thereby lock the hooks in the open position, after release of the load, Fig. 6. A cutaway portion 48 of each hook allows the hooks to overlap within the suspension member 2, Fig. 4. A second piston may replace the spring 40 shown in Fig. 4,