GB2032860A

GB2032860A - Automatic Parachute Releaser

Info

Publication number: GB2032860A
Application number: GB7909907A
Authority: GB
Original assignee: SSE Inc
Current assignee: SSE Inc
Priority date: 1978-10-31
Filing date: 1979-03-21
Publication date: 1980-05-14
Also published as: GB2032860B

Abstract

A parachute system formed by a main chute and a reserve chute (16) has an automatic parachute releaser for the reserve chute which includes a sensor (44) detecting an increasing fall rate of a payload above a trigger level to initiate a timing cycle in a timer (88). If the timing cycle is completed, a single-action actuator (38) automatically releases the reserve chute independently of the main chute releaser. Should the rate of fall decrease below trigger level during the timing cycle because of late opening of the main chute or timely manual release of the reserve chute through its ripcord assembly (20), then automatic operation of the actuator is cancelled by automatic reset of the timer in response to cessation of the triggering signal from the sensor. <IMAGE>

Description

SPECIFICATION Automatic Parachute Fleleaser This invention relates to the opening of a reserve chute of a parachute system should the main chute fail to open or malfunction.

The automatic opening of parachutes as an alternative to manual opening through a conventional ripcord assembly is well known as disclosed in U.S. patent Nos. 3,112,091, 2,437,295, and 3,507,468. According to U.S.

patent No.3,112,091 to Snyder, an electrically triggered, explosive type of actuator is operative through the conventional ripcord assembly to release a chute upon receipt of a signal from a barometric device detecting an opening altitude.

According to U.S. patent No. 3,507,468 to Lancaster, a differential pressure type of fall rate sensor having a timing device associated therewith, is operative to automatically release a reserve chute for opening thereof when an excessive fall rate is detected. The fall rate trigger level is preset through the timing device to reflect malfunction of the main chute without any connection thereto. Release of a reserve chute for the same purpose is disclosed in U.S. patent No.

3,437,295 to Istel et al. However, automatic opening of the reserve chute according to the Istel patent is effected at the end of a preset timingcycle initiated by release of the main chute through the main ripcord. The timer must, therefore, be manually reset if the main chute does properly open. The latter type of automatic opening system for a reserve chute is not as desirable as the type disclosed in the Lancaster patent because it does not take into account the rate of descent and requires manual reset of the timer to cancel opening of the reserve chute.

Automatic opening of a parachute in response to an excessive rate of fall is well-known as disclosed in each of U.S. patent Nos. 3,300,606 and 3,667,705 and in the Lancaster patent aforementioned, all utilizing a differential pressure type of descent rate sensor. Despite the crowded nature of the relevant prior art as exemplified by the foregoing patents, no provision was heretofore made to cancel automatic operation of the actuator in the event the chutist does manually release the reserve chute through the ripcord handle in a timely fashion or if the main chute fully opens somewhat late. This presents a problem when utilizing an explosive type of single action actuator since a prematurely triggered actuator must be recharged.

It is therefore an important object of the present invention to provide for automatic opening of a reserve chute upon detection of an excessive fall rate reflecting malfunction of the main chute, wherein manual release of the reserve chute in a timely fashion will prevent premature automatic opening operation.

In accordance with the present invention, detection of an excessive fall rate by a sensor produces a signal which closes a normally open power switch connecting a voltage source to a resettable solid state, timer through which power is applied to a single action actuator for automatically releasing the reserve chute which is otherwise manually released through a ripcord assembly. While the sensor is preset to produce the reserve chute opening signal at a rate of fall corresponding to a rate that could cause serious injury, the timer delays automatic signal-triggered operation of the actuator for a timed period to give the chutist an opportunity to manually release and open the reserve chute.If the reserve chute is not timely opened manually to reduce the rate of descent, then the timer is enabled at the end of the timing cycle to effect operation of the actuator for automatic release of the reserve chute. On the other hand, if the rate of descent is reduced below trigger level either by late opening of the main chute or by manual opening of the reserve chute during the timing cycle, the timer is automatically reset in preparation for the next trigger signal from the sensor and automatic operation of the actuator is cancelled.

Figure 1 is a side elevation view of a parachute system installed on a chutist in accordance with the present invention.

Figure 2 is a front elevation view of the reserve chute assembly associated with the parachute system of Fig. 1.

Figures 3a through 3d are simplified illustrations showing an emergency parachute jump sequence.

Figure 4 is a block diagram illustrating the control system associated with the present invention.

Figure 5 is a partial side section view of a rate of descent sensor utilized with the present invention.

Figure 6 is an electrical circuit diagram iilustrating the control system in greater detail.

Referring now to the drawings in detail, Fig. 1 illustrates a chutist 10 outfitted with a parachute system including a main chute assembly 12 supported on the back by a body harness 14 which also supports on the front of the chutist, a reserve chute assembly 1 6. The main chute assembly is adapted to be used on static line jumps so as to be automatically opened after the chutist drops to a predetermined opening altitude below the aircraft exit altitude. The reserve chute assembly 16 may be manually opened in the event the main chute fails to properly open or otherwise malfunctions. The foregoing parachute system is generally well-lenown in the art.

By way of example, Fig. 3a illustrates the chutist 10 dropping from an aircraft 1 8 at an exit altitude of 3,000 feet. At an opening altitude of 2,900 feet, the main chute released by a static jump line 19 does not properly open as depicted in Fig. 3b, so that it does not sufficiently slow the fall or descent of the chutist after acquiring a fall velocity of 50 feet per second, for example. At that point, the chutist continues to fall at an increasing rate for a preset period of time such as 10 seconds, during which time he may manually open the reserve chute as shown in Fig. 3c.

Should the chutist fail to manually open the reserve chute, or if his rate of descent is not reduced below trigger level, the reserve chute 1 6 is automatically opened at the end of the 10 second delay period in accordance with the present invention so that the jump may be successfully concluded as shown in Fig. 3d.

Fig. 2 illustrates the reserve chute assembly 1 6 having a manual ripcord assembly 20 similar to the arrangement disclosed in U.S. patent No.

3,112,091 aforementioned. The ripcord assembly has a handle 21 operative through cords 22 to withdraw pins 24 from cones 26 and thereby release the buckles 28 secured to elastic bands 30. The end flaps 32 of the reserve chute container 34 will then allow the reserve chute to open as is well-known in the art. Also associated with the ripcord assembly underlying the pocket 36 is an electrically triggered, explosive type actuator 38 for automatically withdrawing the ripcord pins 24. Electrical trigger voltage is supplied to the actuator 38 through an electrical cable 40 from an automatic control unit 42 secured at a suitable location. The control unit 42 in accordance with the present invention, is in no way connected to the main chute, either mechanically, hydraulically or electrically.

Associated with the control unit 42 is a rate of descent sensor of the differential pressure type, generally referred to by reference numeral 44 in Fig. 5. In this type of sensor a plenum chamber 46 is enclosed in the body 48 of the sensor to which a restricted inflow of ambient air is conducted through a capillary flow conduit or wick 50. The chamber 46 is pressure sealed by an O-ring seal 52 and a flexible diaphragm 54. The diaphragm is exposed to ambient air pressure on one side thereof opposite the chamber 46 through an opening 56 in cover 58. The diaphragm is spaced by an adjustable amount from the end of an adjustment screw 60 threadedly mounted by an internal nut portion 62 of the sensor body. The screw 60 projects axially from a shank 64 to which a slotted head 66 is connectcd.An O-ring seal 68 seated in an annular groove in the shank completes the sealing of the plenum chamber 46.

The shank 64 and diaphragm 54 are made of electrically conductive material so as to establish electrical contact when the external ambient air pressure acting on one side of the diaphragm exceeds the internal reference air pressure in plenum chamber 46 by a predetermined amount, preset by the adjustable positioning of the screw 60 through rotation of the head 66 by a tool.

When electrical contact is made, a circuit is completed between electrical conductors 70 and 72. Conductor 70 is electrically connected to the diaphragm 54 while conductor 72 is electrically connected to shank 64 through contact disc 74. A spring 76 biases the disc 74 into contact with the adjustment head 66 within the recess 78 formed in the sensor body.

Fig. 4 diagrammatically illustrates the reserve chute opening control system of which the manual ripcord assembly 20, actuator 38 and sensor 44 are components. A contact closure signal from the sensor 44 reflecting detection of an excessive rate of descent is amplified by amplifier 80 to close a power switch 82. By means of the power switch, a source of power 84 to a resettable timer 88. The timer when enabled, supplies the electrical energy from source 84 to the actuator 38 through an output amplifier 86 causing ignition of the explosive within the actuator to automatically open the reserve chute 1 6 in response to detection of the excessive fall rate by the sensor as aforementioned. However, the amplifier 86 remains disabled for a predetermined delay period following the signal from the sensor under control of the timer 88.The timer is of the type that is automatically reset during its timing cycle should there be any cessation of the triggering signal from the sensor 44 causing the power switch 82 to open and cut off supply of voltage from the power source.

Closing of the power switch by a subsequent signal from the sensor initiates a new timing cycle at the end of which the amplifier 86 is enabled.

The electrical control circuit embracing the power source 84, sensor 44, amplifier 80, power switch 82, timer 88 and amplifier 86 is shown in greater detail in Fig. 6. The source 84 in the form of a DC battery has its positive terminal connected to the amplifier 80 upon closing of the contact in sensor 44. The amplifier includes a coupling resistor 90 through which signal current from the battery is conducted to the base of a transistor 92 having an emitter connected to the negative terminal of the battery and an output collector. A negative base bias is maintained on the base by resistor 94 connected to the negative terminal of the battery.

A negative amplified voltage signal is applied through resistor 96 from the output collector of the amplifier to the base of transistor 98 of the power switch 82. A positive cut-off bias is applied to the base of a switching transistor 98 from the positive terminal of battery 84 through resistor 100 to normally hold the power switch open or non-conductive. The transistor 98 is therefore switched on by a negative signal voltage from the amplifier 80 to conduct current from the battery through its emitter-collector circuit establishing a positive battery voltage across lines 102 and 104 for the duration of the signal output from the sensor 44.

The timer 88 is connected across the voltage lines 102 and 104 and includes an integrated circuit chip 106 having a trigger terminal 108 connected to the junction of the positive voltage line 102 and one side of capacitor 110. The capacitor 110 applies a negative going pulse to the trigger terminal upon closing of the power switch 82 to initiate a timing cycle of a duration determined by capacitor 112 and adjustable timing resistor 114. The timing cycle is interrupted by opening of switch 82 before the end of the timing period causing capacitor 110 to discharge and reset the timer circuit 106. Upon completion of a timing cycle a negative voltage at the output terminal 116 is applied to the base of transistor 11 8 of the amplifier 86.

An output pulse from the timer circuit 88 switches on transistor 11 8 causing it to conduct and apply a positive voltage to the base of transistor 120. An amplified negative pulse is thereby established at the collector of transistor 120 to switch on driver transistor 122 which conducts current from positive voltage line 102 to the actuator 38 through cable 40.

A test switch assembly 1 24 is provided for the control unit 42 as shown in Fig. 6. Upon actuation of the test switch from its normally open position as shown, the battery is directly connected to the actuator (or preferably a dummy actuator) in series with resistor 126 and on LED indicator 128. Also, a second LED indicator 1 30 is directly connected across the battery terminals in parallel with resistor 1 32. The indicators 1 28 and 1 30 are therefore operative to indicate actuator malfunction or battery failure or both should an indicator or indicators fail to illuminate upon actuation of the test switch 124.

It will be apparent from the foregoing description that the control unit 42 is effective to insure opening of the reserve chute 1 6 when the sensor 44 detects an excessive fall rate because of main chute malfunction, yet prevents premature trigger of the single-action explosive actuator 38 by cancelling automatic operation during the timing cycle of the resettable timer 88.

The foregoing is accomplished by a novel relationship of the timer 88 and power switch 82 to an otherwise generally known fall rate sensor triggered release system for a reserve chute.

Claims

1. In combination with a rate of descent sensor adapted to be carried on a payload of a parachute system having a main chute deployed to retard descent of the payload, a manually releasable reserve chute and a powered release mechanism for automatically opening the reserve chute in the event the main chute fails to prevent an increase in the rate of descent above a predetermined level, a resettable timer device having a timing cycle, amplifier means connecting the sensor to the timer device for initiating said timing cycle in response to detection of a rate of descent above said predetermined level, output means connecting the timer device to the release mechanism for operation thereof to deploy the reserve chute at the end of said timing cycle, and switch means interconnecting the amplifier means and the timer device for resetting the timer device during said timing cycle in response to any decrease in the rate of descent below said predetermined level to cancel automatic operation of the powered release mechanism.

2. The combination of claim 1 wherein said output means includes an output amplifier and a source of voltage connected by the switch means to the amplifier.

3. The combination of claim 2 wherein said power release mechanism includes explosive means electrically detonated by the amplifier for generating explosive energy, and means connected to the explosive means for converting said explosive energy into motive actuating energy.

4. In combination with a rate of descent sensor adapted to be carried on a payload of a parachute system having a main chute deployed to retard descent of the payload, a manually releasable reserve chute and a release mechanism for opening the reserve chute in the event the main chute fails to prevent an increase in the rate of descent above a predetermined level, a resettable timer device having a timing cycle, a source of voltage, signal operated switch means connecting said source to the timer device for resetting thereof during the timing cycle whenever the rate of descent drops below said predetermined level, actuating means connected to said switch means and the timer device for operating the release mechanism at the end of a timing cycle, and amplifier means connecting the sensor to the switch means for initiating said timing cycie in response to detection of an increase in the rate of descent above said predetermined level.

5. In combination with a parachute system having a main chute adapted to be deployed to retard descent of a payload, a reserve chute opened in the event the main chute fails to prevent an increase in the rate of descent of the payload above a predetermined level, a manually operable ripcord assembly connected to the reserve chute for opening thereof, a single-action actuating mechanism connected to the ripcord assembly for automatically opening the reserve chute in response to a release signal and a rate of descent sensor for producing the release signal in response to detection of a rate of descent above said predetermined level, the improvement residing in a resettable timer device having a timing cycle, a source of energy, power switch means connecting said source to the timer device for preventing reset thereof during the timing cycle, amplifier means connecting the sensor to the power switch means for initiating the timing cycle in response to the release signal and effecting reset upon cessation thereof during the timing cycle, and output means connected to the source by the power switch means for triggering the actuating mechanism in response to completion of said timing cycle by the timer device.