GB1325083A - Parachute deployment system - Google Patents

Abstract

1325083 Radar M L AVIATION CO Ltd 8 May 1972 [12 Feb 1971] 4566/71 Heading H4D [Also in Division B7] Apparatus for association with a parachute, particularly for supply dropping, to effect deployment of the parachute at a predetermined altitude comprises a transmitter 1 for transmitting a frequency-modulated carrier wave, a receiver 2 which receives signals reflected from the ground always at a different frequency from those transmitted, a filter 3 to which the signal from receiver 2 is fed to remove the modulating wave. The signal is then passed to a high pass filter 4 to remove the carrier wave thus leaving the beat or difference frequency between the transmitted and received signals, which is passed to an amplifier 5. The output from the amplifier is fed to a Schmitt trigger 6 which produces a pulse at a preset input level, such pulses being counted by an integrator stage 7 and the resulting D.C. voltage, which is proportional to the altitude, is used to set a further Schmitt trigger 8, which is arranged toreset toits normal state after the pro-selected deployment height. The device is energized by a battery 14 via a switch 15 closed by a lanyard when the parachute is dropped. A relay 9 is provided to be energized in the absence of a signal or in the presence of a signal equivalent to an altitude below the preset level, and a further relay 10 is arranged as a delayed arming system to ensure that the circuit will not be armed until a height of between 1À2 and 2À2 times the preset height is passed within a period of 3 seconds. When the beat or difference frequency falls to that corresponding to the preset height relay 9 will pull in to complete the circuit to a connector 12 which will operate a cable cutter or other device to initiate deployment of the parachute.