US3922948A - Detonating system - Google Patents

Abstract

In the device disclosed an explosive pellet which releases a bomb lock on an aircraft is detonated remotely by applying an enabling pulse to a relay near the pellet and a second detonating pulse through a line to the pellet, which line is completed by the contact of the energized relay. Ground connections to the frame of the aircraft complete the detonator pulse circuit. Separate electrical lines actuate the relay and keep it floating in order to avoid the ground return.

Description

fitted States Patent 1 1 3,922,943

Krehan cc. 2, 1975 DETONATING SYSTEM 2982180 5/1961 Hart 89/15 F 331959 5 1967 V D 2]. 102 .2 R [75] Inventor: Friedrich Wilhelm Krehan, Munich, 5 an Om at 1 HO Germany I Primary E.\'am1'nerStephen C. Bentley [73] Assigneez Messerschmltt-Bolkow-Blohm Assistant Jordan Mumch Germany Attorney, Agent, or FirmToren, McGeady and 22 Filed: Mar. 25, 1974 stanger [21] Appl, No.: 454,548

{57] ABSTRACT [30] Foreign Application Priority Data in the device disclosed an explosive pellet which re- M1111 29, 1973 Germany 2315704 leases a bomb lock on an aircraft is detonated remotely by applying an enabling pulse to a relay near [52] U.S. Cl 89/15 F; 102/702 R the pellet and a econd detonating pulse through a line [51] Int. Cl. F42C 15/12 to h ll t, hi h line is completed by the contact of Fleld 0f sealdlw 102/702 89/15 E, the energized relay. Ground connections to the frame 89/l-5 F of the aircraft complete the detonator pulse circuit. Separate electrical lines actuate the relay and keep it References Cited floating in order to avoid the ground return.

UNITED STATES PATENTS 2,912,902 11/1959 Nessler 89/15 F 6 Clams 2 Drawmg Figures DETONATING SYSTEM BACKGROUND OF THE INVENTION This invention relates to means for setting off explosive detonators, and particularly for releasing a bomb lock.

Such bomb locks are released by electrically igniting a pyrotechnic cartridge whose housing is grounded to the bomb lock by a metallic connection that serves as a return line for electrical signals.

This type of bomb lock, which is used for dropping bombs, missiles, and similar payloads from bombcarrying aircraft, is shown for example in the publication of the ML Aviation Company Ltd., Maidenhead, Berkshire, England, entitled Ejector Release Units, No. 119 Mk.1, No. 120 Mk.l, dated Dec. 1967. In such systems, undesired release of the payload is avoided by utilizing two autonomous jointly-necessary detonating signals. The detonating circuit includes a multi-wire arrangement and a so-called detonating pulse stepping switch. In the operating mode the switch transmits the actual detonating pulse to the primer pellets of pyrotechnic cartridges. If a single signal, that is, an undesired one, accidentally occurs at one of the input terminals of the detonating pulse stepping switch, ignition does not follow.

In a simple embodiment, the detonating pulse stepping switch is a relay whose operating contact closes an ignition line. The detonating signals are generated at a command location remote from the stepping switch. Suitable grounds provide the return path for the signals.

Such systems have disadvantages. In particular, these circuits failto prevent accidental ignition under all circumstances.

An object of this invention is to avoid these disadvantages.

Another object of the invention is to prevent uncontrolled dropping of payloads.

SUMMARY OF THE INVENTION According to a feature of the invention these objects are attained in whole or in part by bypassing the ground connections in one of the two jointly necessary circuits and allowing one of the two circuits to float electrically either at the command location or the stepping switch location.

Where the stepping switch is composed of a relay, one line carries an enabling pulse from the command location to the relay and a second line returns the pulse to the command location so that the relay floats electrically. This enables the stepping switch so that a detonating pulse from the command location can pass to the explosive pellet.

The invention is based upon the recognition that, under certain circumstances, undesired electrostatic charges which produce voltage differences of several hundred volts between ground connections superimpose themselves on the switching level of the signals from the command locations to the detonating pulse stepping switch so that ignition pulses are simultaneous. This produces accidental release of the bomb lock and may destroy the ignition pulse stepping switches and/or the ignition pulse generator. Such interference voltages may occur for example when lightning strikes the aircraft.

The invention overcomes the effect of such electrostatic charges because control lines free of this static are used for actuation of the detonating pulse stepping switch. Thus static charges along the aircraft structure, lightning bolts, and similar physical phenomena do not result in any changes in the switching level of at least one of the signal inputs of the detonating pulse stepping switch. Thus undesired release of bombs, missiles. and similar explosive-carrying payloads or fuel containers is reliably avoided.

These and other features of the invention are pointed out in the claims. Other objects and advantages of the invention will become evident from the following detailed description when read in light of the following drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram illustrating a circuit arrangement for releasing a bomb lock according to the prior art; and

FIG. 2 is a bomb lock releasing circuit embodying features of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS In the prior art circuit arrangement of FIG. 1, a grounded generator G having two input terminals 2 and 3 is connected, via two lines 4'and 5, to a detonating pulse stepping switch ZF. A detonating explosive pellet Z connected to the output of the stepping switch ZF releases a bomb lock, not shown. The latter may be replaced by other types of detonatable devices such as a pyrotechnic gas producer, a blasting stick, a rocket engine, or the like. Within an aircraft, the generator G is remote from the stepping switch ZF and the pellet Z.

Within the generator G a source S grounded to a metal portion of the aircraft applies current through the emitter-collector path of a transistor TRll, the line 4, a winding (also grounded to the metal of the aircraft at a point remote from the source ground) of a relay R, and the return path through the metal grounds, when a first detonating signal is applied between the terminal 3 and ground. As a result the winding of the relay R closes its contact rl. If a second detonating signal is applied between the terminal 2 and ground simultaneously with the first detonating signal at the terminal 3, the source S supplies current through a transistor TR2, the line 5, the contact r], the pellet Z, and the ground return connection to the source. The signals at the terminals 2 and 3 are generally in the form of pulses. The first signal between the terminal 3 and ground is an enabling pulse while the second signal between the terminal 2 and ground is the actual detonating pulse. The detonating pulse sets off the pellet Z.

The pellet Z opens the bomb lock or actuates any other type of explosively actuable device. Suitable circuits apply the voltages between the terminal 2 and ground on the one hand, and the terminal 3 and ground on the other hand. The two separate signals and the system utilizing the two separate signals create an operation that prevents accidental detonation However, it has been discovered that certain electrical conditions may accidentally create sufficiently high voltages between the ground points so as to cause accidental detonation of the pellet Z.

The circuit of FIG. 2 eliminates problems of this sort while retaining the desired two-signal operation. In FIG. 2, suitable circuits similar to those of FIG. 1 apply the necessary pulse signals across the terminal 3 and ground on the one hand and across the terminal 2 and ground on the other hand. Similarly the pellet Z is positioned to open a bomb lock or to actuate any other cxplosively operable device not shown. The circuits for applying the pulse signals at the terminals 2 and 3 are also not shown. The circuit of FlG. 2 corresponds to that of FIG. 1. However, here the winding of the relay R, instead of being grounded at the pellet location. is grounded through an electrically floating line 6 at the ground point of the source S. Thus, a detonating pulse applied at the terminal 3 causes current to flow from the source S, through the transistor TRl, through the line 4, through the winding of the relay R, through the line 6, and back to the source S without passing through the metal structure of the aircraft. If a pulse appears simultaneously at the terminal 2, the source S simultaneously sends a detonating current through the transistor TR2, the line 5, the contact r1 which has been closed by the current through the winding of the relay R, the pellet Z, and the ground return through the aircraft structure. This causes explosion of the pellets Z and actuation of the bomb lock.

Interference voltages produced by lightning or similar charges can, therefore, no longer have any effect on line 4 or line 6. Thus, superposition of the control signals for the detonating pulse stepping switch and an interference voltage can no longer take place. Release of the primer pellet Z by undesired interference signals can, therefore, no longer occur.

The current flow description with respect to FIGS. 1 and 2 have for simplicity been described as passing from the negative terminal of source S to the positive. For accuracy, this can be considered as a negative current flow.

Effectively the current through the relay R is an enabling current while the current through the contact rl is the actual detonating current. Nevertheless these can both be considered as simultaneously necessary detonating signals.

What is claimed is:

I. A circuit arrangement for releasing a bomb lock of an aircraft. comprising an electrically ignitable primer cartridge for opening the bomb lock, said cartridge having a housing grounded to the aircraft structure, an ignition line connected to the cartridge. a pair of floating leads, a command switch for generating a detonating pulse and a relay switching pulse, a relay having a winding and a contact said contact being connected to the ignition line, said winding being connected via the floating leads with the command switch, said command switch actuating said winding through said floating leads and passing an ignition current through said ignition line. i

2. A control system for an explosively actuated device, comprising an electrically actuable explosive detonator having a housing, a first circuit, a second circuit, said first circuit when enabled and when actuated setting off said detonator, said second circuit when actuated enabling said detonator. said detonator having a ground connection, said first and second circuits having a command station grounded at a point remote from the ground of said detonator, said circuits having a response portion located near said detonator, one of said circuits connecting the command portion and the response portion with floating leads.

3. An apparatus as in claim 2, wherein said command portion includes a pair of grounded pulse generators.

4. An apparatus as in claim 3, wherein said response portion includes a switch system, said enabling circuit including the input of the switch system and said detonating circuit including the output of said switch system.

5. An apparatus as in claim 2, wherein said second circuit includes the floating lines.

6. An apparatus as in claim 5, wherein said first circuit utilizes the ground connections as a return.

Claims (6)

1. A circuit arrangement for releasing a bomb lock of an aircraft, comprising an electrically ignitable primer cartridge for opening the bomb lock, said cartridge having a housing grounded to the aircraft structure, an ignition line connected to the cartridge, a pair of floating leads, a command switch for generating a detonating pulse and a relay switching pulse, a relay having a winding and a contact said contact being connected to the ignition line, said winding being connected via the floating leads with the command switch, said command switch actuating said winding through said floating leads and passing an ignition current through said ignition line.

2. A control system for an explosively actuated device, comprising an electrically actuable explosive detonator having a housing, a first circuit, a second circuit, said first circuit when enabled and when actuated setting off said detonator, said second circuit when actuated enabling said detonator, said detonator having a ground connection, said first and second circuits having a command station grounded at a point remote from the ground of said detonator, said circuits having a response portion located near said detonator, one of said circuits connecting the command portion and the response portion with floating leads.

3. An apparatus as in claim 2, wherein said command portion includes a pair of grounded pulse generators.

4. An apparatus as in claim 3, wherein said response portion includes a switch system, said enabling circuit including the input of the switch system and said detonating circuit including the output of said switch system.

5. An apparatus as in claim 2, wherein said second circuit includes the floating lines.

6. An apparatus as in claim 5, wherein said first circuit utilizes the ground connections as a return.

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