US3039363A

US3039363A - Rocket firing relay

Info

Publication number: US3039363A
Application number: US5321A
Authority: US
Inventors: Salvatore J Grillo; William B Walker
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-01-28
Filing date: 1960-01-28
Publication date: 1962-06-19
Anticipated expiration: 1979-06-19

Description

June 19, 1962 s..1. GRILLO ETAL 3,039,363

ROCKET FIRING RELAY Filed Jan. 28, 1960 United Patented June 19, 1962 .Cree

3,039,363 RCKET FIRING RELAY Salvatore J. Grillo, New Britain, and William B. Walker, Hatboro, Pa., assignors to the United States of America as represented by the Secretary of the Navy Filed Jan. 28, 1960, Ser. No. 5,321 3 Claims. (Cl. 89-1.7) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America Ifor governmental purposes Without the payment of any royalties thereon or therefor.

'Ihis invention relates to an electric ignition circuit and relay for firing a rocket and more particularly to an electric ignition circuit and relay 'for ring a rocket by maintaining a detonating charge electrically isolated until a prescribed instant of launching.

Electrically ignited rockets red from a launcher present a hazardous possibility of premature ring due to an undesirable electrical current appearing in the ignition circuit. This current is primarily caused by stray currents conductively leaking into the circuit from adjacent electrical `gear or by induction occurring when the circuit is in a field of electromagnetic energy such as emitted by radar transmitters and other high Ifrequency radio transmitters. In applications where the rockets are to be tired from vehicles, such as -an airplane, the launchers are necessarily located outboard of the vehicle. The rockets must therefore be pre-loaded and electrically armed for remote actuation at a later time. Remote electrical actuation often entails long conductor leads yfrom the rocket launcher to a remote actuating device and hence obviously multiplies many times the hazard of premature iiring. A larger area is exposed to conductive leakage and also'the accompanying antenna eifect of the conductor leads are such as may produce a stray or an induced current suicient in magnitude to ignite a highly sensitive electrically responsive ydetonating charge in the rocket.

Various methods and `devices have been contrived for safeguarding against premature ring of rockets of the character described. One of such devices consists of using high frequency filters and luy-passes. Complete attenuation of all frequencies, as may be induced by electromagnetic waves, is diicult and requires a complex electrical network; moreover, the network cannot discriminate between a real :signal and an identical false signal induced or conducted from an external source. Another device short-circuits the electrical leads. Obviously, a positive short is required in order to assure no voltage drop is applied across the detonating charge. Being a temporary connection, the likelihood of always having a positive short is seriously diminished. Furthermore, the short-circuiting device must be located at the rocket, hence additional means for removing the device is required. Each of these electrical devices still involves dangerously long leads continuously connected between the detonating charge and -a remotely located initiating device. Coupling the last-mentioned fact with the disadvantages of the particular device selected simply returns the hazard of premature rocket firing to its original gravity.

The main concept upon which the present invention is premised resides in attaining an ignition circuit which permits the loading of a rocket in the launcher and the arming of the detonating charge for remote actuation thereof and which further maintains the charge electrically isolated frorn the ignition circuit until the prescribed instant of rocket launching. The general purpose of this invention is to provide a means for obtaining electrical isolation of the detonating charge Ifrom the ignition circuit at a point in close proximity to the rocket launcher and which embraces all of the advantages of the similarly employed iilter, by-pass and short-circuit type ignition circuits and possesses none of the aforementioned disadvantages. To attain this, the present invention contemplates a relay and shield mounted on the rocket launcher whereby the electrical leads connected to the detonator terminate at the rocket launcher and remain electrically isolated from the ignition circuit until a prescribed instant of ring. Hence, the distance of the actuating switch from the launcher is immaterial.

It is an object of the present invention to provide a novel rocket firing circuit for electrically isolating the leads connected to an electrically responsive detonating charge at the launcher to diminish the possibility of premature firing.

Another object of the invention is the provision of a novel rocket firing relay responsive to remote actuation and adapted to be mounted in a launcher for maintaining short electrical leads connected to an electrically responsive detonating charge.

A further object of the invention is directed to providing a unique electromechanical relay for selectively and irrevocably connecting a circuit.

Still another object of the invention is to provide an improved and economical relay of simplified design.

These and other objects and many of the attendant advantages of the present invention will be readily appreciated as the same become better understood -by reference to the Afollowing detailed description when considered in connection with the accompanying drawing, wherein:

FIG. l is a fragmentary longitudinal sectional view of the `breech end portion of a rocket launcher showing in partial eros-section the aft end portion of a rocket and a rocket tiring relay positioned in the launcher for tiring;

FIG. 2 represents an end View of the rocket firing relay taken along the line 2-2 in FIG. l; and

FIG. 3 is a schematic diagram of the ignition circuit -of the rocket shown in FIG. l.

Referring now to the drawing, wherein like reference characters designate like or corresponding parts throughout the several views, there is illustrated in FIG. 1 the breech end portion of a barrel 10 of a rocket launcher having an end llange 11. The aft end portion of a rocket indicated generally by the numeral 12 is illustrated by a propellant tube 13 andpfour nozzles 14 alternately spaced with four stabilizing iins 16. The fins 16 are urged toward a spreading position 4'about pivots 17 on nozzles 14 by iin ractuator 18 having a piston 19 subjected to gas pressures generated in the tube 13.

The tube 13 is connected to the nozzles 14 by retaining ring 21 and includes a rnain propellant 22 ignited by an ignition charge 23 which in turn is detonated by a primer 24. The primer 24 includes an electric hot Wire 26 embedded in a pyrotechnic pellet 27. The wire 26 is grounded at one end to propellant tube 13 by conductor 28 and is connected by insulated conductor 31 at the other end to a contact button 29 which is also insulated from the ground. The nozzles 14 include a cement-like sealant 32 that is expelled by gas pressure in tube 13. The button 29 is retained in the position shown by notches 33 in the tins 16, hence the button 29 is released when the iins 16 spread outwardly. i

While the drawing shows a rocket with some specicity in order to show theenvironment of the rocket tiring relay, it will be readily understood that any suitable soli'dor liquid-propellant type rocket may he used in connection with the present invention. v

A rocket iiring relay indicated generally lby the numeral 34 is comprised of a non-conductive insert 36 and a nonconductive housing 37 secured on opposite sides of a metal shield 38 by countersunk screws 40. Insert 36 and housing 37 are preferably fabricated of a phenolic 3 resin material. The shield 38 affords complete isolation of conductors 28 and 31 from any electromagnetic waves present around the launcher area. The relay 34 is inserted in tube 13 until shield 38 positively contacts flange 11. The contact is maintained by detents 39.

A spring-actuated plunger 41 is centrally ldisposed in the insert 36 for making electrical contact with the button 29. A bifurcated contact 42 fixed to the housing 37 is connected to plunger 41 by an insulated conductor 43. A cover plate 44 encloses the housing 37.

As best seen in FIG. 2, the contact 42 is positioned in housing 37 for engaging contact spring 46 which is xed to housing 37 by screw fasteners 47. The spring 46 is connected to an electrical resistance-type heater 48 which in turn is connected to one end of a current limiting resistor 49, the other end being grounded on shielded cable 51. An insulated conductor 52 of cable 5l provides an electric ignition signal from an electrical power source 53 through a manual switch 54, as shown in FIG. 3. The cable 51 terminates in a jack 56 for convenient electrical connection.

The heater 48 is fixed to housing 37 by lugs 57 and a loop of thread 58 around the heater 48 restrains spring 46 in stressed position out of engagement with the contact 42. The thread 58 is of a readily fusible material which breaks when a sufficient current is passed through heater 48.

FIG. 3 schematically illustrates the manner in which the relay 34 of FIGS. 1 and 2 is connected in the ignition circuit for tiring the rocket. The electric power source 53, the manual switch 54, the contact 42 and the primer 24 are arranged in series, while heater 48 and resistor 49 are arranged in parallel with the contact 42 and primer 24. The current limiting resistor 49 assures that a major portion of the current at terminals A and B appears in the circuit branch containing primer 24.

The firing operation of a rocket will now lbe summa- Iized. The rocket 12 and` relay 34 are inserted into the launcher barrel in the respective positions shown and the ignition circuit is armed by connecting the shielded cable 51 to the electrical power source and the manual switch 54. The spring contact 46 is held in an open position by the thread 58. Closing the manual switch 54 energizes the heater 48 and fuses the thread 48 until it Ibreaks and releases the contact spring 46. 'Ihe spring contact 46 strikes and engages contact 42 whereby the primer 24 is energized. It is contemplated that a relatively strong electrical signal is required to fuse thread 58 thereby precluding the possibility of heater 48 being sufficiently energized by an undesirable electrical signal caused by stray currents due to leakage or induced currents due to surrounding electromagnetic waves.

It is contemplated that the exposure area of contact 42 be very small in relation to the distance between contact 42 and contact spring 46 whereby Contact 42 remains completely isolated from the external ignition circuit until a prescribed instant of ring the rocket 12. It should thus be apparent that contact 42 and a small portion of conductor 43 are the only ungrounded ele'ctrical elements which are continuously connected to primer 24. In this manner the possibility of an undesirable electrical signal appearing at primer 24 and resulting in premature ignition is practically eliminated.

It should be understood,` of course, that the foregoing disclosure relates only to a preferred embodiment of the invention and that numerous modiiications and variations may be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. For an electrically tired rocket having its ignition conductor extending from within to an electrical terminal fixed at its read-end, the combination comprising: an electrically grounded launching tube formed for sliding said rocket endwise therein, a metallic electrical shielding plate having its inner face abutting and covering the breech end opening of said launching tube for grounding any radiation-induced electrical signals, a yieldable electrical contact carried on the inner face of said plate and aligned to operably connect with said terminal, force-exerting means carried by said plate and operable on said yieldable contact to obtain an electrical connection between said yieldable contact and said terminal when said rocket is positioned in said launching turbe for firing, a stationary electrical contact iixed with respect to said plate electrically connected to said yieldable contact and having only a small portion exposed at the outer face of said plate, a movable electrical contact carried on the outer face of said plate and aligned to selectively engage said portion, forceexerting means carried by said plate and operable on said movable contact to move said movable contact into engagement with said portion when it is unopposed, rigid heater means lixed to said plate and electrically connected between said movable contact and ground, a fusible link connected between said heater and said second-named force-exerting means operable to selectively maintain said movable contact a relatively large distance awayV from said portion and to oppose said force-exerting means, detent means carried by said plate for yieldably maintaining a high pressu-re connection between said inner face of said plate and the breech end opening of said launching tube; whereby, when the movable contact and said heater means are connected to the ungrounded terminal of a remotely located power supply, the other terminal of the power supply being grounded, said heater will generate suflicient thermal energy to fracture said fusible link and said movable contact will be propelled into engagement with said portion of said stationary contact thereby providing an electrical signal to the ignition conductor sufficient to lire said rocket from said launching tube.

2. For an electrically tired rocket having its ignition conductor extending from within to an electrical terminal mixed at its rear-end, the combination comprising: an electrically grounded launching tube formed `for sliding said rocket endwise therein, a metallic electrical shielding plate having its inner face abutting and covering the Ibreech end opening of said launching tube for grounding any radiation-induced electrical signals, a relatively small stationary electrical contact carried on the outer face of said plate, conductor means connected to said stationary contact but not exposed to the outer face of said plate and extending through said plate for connection to said terminal when -said rocket is positioned Iin said launching tube, a movable electrical contact carried on the outer :face of said plate and raligned to selectively engage said stationary contact, vtorce-exerting means carried by said plate and operable on said movable contact to move said movable contact into engagement with said stationary contact, when it is unopposed, rigid heater means lixed to said plate :and electrically connected between said movable contact and ground, a fusible link connected between said heater and said force-exerting means operable to selectively maintain said movable contact a relatively large distance away from said stationary contact and to oppose said force-exerting means; whereby, when the movable contact vand said heater means are connected to the ungrounded terminal of -a remotely located power supply, the `other terminal of the power supply being grounded, said heater will generate sufficient thermal energy to fracture said fusible link, and said movable contact will be propelled into engagement with said stationary contact thereby providing an electrical signal to the ignition conductor sufficient to lire said rocket from said launching tube.

3. For an electrically tired rocket having its ignition conductor extending from within to an electrical terminal at its rear-end, the combination comprising: an electrically grounded launching tube formed for sliding said rocket endwise therein, a metallic electrical shielding plate having its inner face enclosing the breech end opening of said launching tube for grounding :any radiationinduced electrical signals, a relatively isolated electrical contact iixed in said plate having a relatively small portion at one end exposed on the outer face of. said plate and the other end formed for connection to said terminal when said rocket is positioned in said launching tube, a movable electrical contact carried on the outer face of said plate and :aligned to Iselectively engage said one end, iiorce-exerting means carried by said plate Iand operable on said movable contact to move said movable contact into engagement with said one end when it is unopposed, rigid heater means fixed to said plate and electrically connected between said movable contact and ground, a 'fusible link connected .between said heater and said force-exerting means operable to selectively maintain said movable contact a relatively large distance away from said stationary 10 said launching tube.

References Cited in the file of this patent UNITED STATES PATENTS 15 2,798,492 Sage et al May 28, 1957 2,821,139 Apstein etal Ian. 28, 1958 2,832,265 Reid `et al Apr. 29, 1958