US 3610091 A
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Description (OCR text may contain errors)
Oct. 5, 1971 R. BORNAND 3,610,091
BIIJLISTIC DEVICE COMIRISING A PROJECTILE AND ITS LAUNCIIER Filed Feb. 1o, 1969 05597 me/mwa United States Patent O 3,610,091 BALLISTIC DEVICE COMPRISING A PROJECTILE AND ITS LAUNCHER Robert Bornand, Meyrin, Geneva, Switzerland, assigner to Transurvey Holding Company Inc. Filed Feb. 10, 1969, Ser. No. 798,058 Claims priority, application Switzerland, Feb. 8, 1968, 2,075/ 68 Int. Cl. F41f 1/06 U.S. Cl. 89-1 F 8 Claims ABSTRACT F THE DISCLOSURE The present invention relates to a ballistic device cornprising a projectile and its launcher, the projectile cornprising a rearwardly extending tube which is radially indeformable under the pressure developed during burning of a launching charge and which is hermetically sealed axially by a piston. The launcher comprises a guide rod in contact with the piston and ignition means for the launching charge, characterized in that the said ignition means is electrical in nature and is disposed at least in part in the piston and is externally actuated by means of the guide rod.
The attached drawing shows, by way of example, one embodiment of a device according to the invention, in which the projectile is in the form of a self-propelled grenade.
In the drawing:
FIG. l is a View partially in axial section, with the parts in their position immediately before firing;
FIG. 2 is a view partially in elevation, with parts in axial section in the position they occupy after firing, when the grenade is just leaving the guide rod which forms a portion of the launcher; and
FIG. 3 is an axial cross-sectional View to a larger scale of a portion of FIG. 1 showing in detail the ignition means for the launcher charge.
Referring now to the drawing in greater detail, the illustrated ballistic device comprises a self-propelled projectile comprised by a head 1 which is screwed on the forward externally screw-threaded portion 2a of a tube 2 whose rear portion carries fins 2b as well as a screwthreaded annular retaining ring 3. Immediately behind the portion 2a of tube 2 is disposed au explosive charge 4 which is compressed by a metal piston 5 which may for example be of brass and which is force fitted into the recess in tube 2 from the rear end of tube 2 before retaining ring 3 is added. The pressure exerted by piston 5 may for example be 400 to 800 kg./crn.2. The apparent volume of explosive charge 4, including the interstices between the powder grains, therefore entirely lls the space between the rear wall of portion 2a and the piston 5.
Piston 5 is traversed by an axial hole, in the rear portion of which is disposed a pin 6 of electrically insulating material, in which in turn is screwed a cylindrical brass rod 7 which bears against an insulating plug 8 which hermetically closes the forward end of the axial hole. The plug S is traversed by a tail 9a of a brass capsule 9 containing a powdered primer and a metallic filament (not 3,610,091 Patented Oct. 5, 1971 shown) which glows incandescent upon electrical resistance heating. The body of capsule 9 is for the most part surrounded by a steel ring 10 while the tail 9a is screwed into the brass rod 7.
In the rear or lower portion of the bore of the insulating pin 6 is disposed a hollow brass contact 11 which is acted upon by a compression spring 12 that also bears against rod 7, so that the head of contact 11 emerges somewhat from the rear wall of piston 5, this rear wall in turn comprising the bottom of a rearwardly opening cylindrical seat formed in piston 5.
In the rear cylindrical seat thus formed in piston SV is disposed, before the ignition of the launcher charge, the forward end of a steel guide rod 13 whose rear head 13a is provided with screw threading permitting it to be screwed into a support forming part of the launcher proper' (not shown) or which may be connected by an adapter to the muzzle of any desired firearm. The forward end of the guide rod 13 is provided with a recess lined with a cup 14 of insulating material at the bottom of which is disposed a contact lug 15 of stainless steel whose purpose is to establish electric contact with the portion of the contact 11 that emerges from piston 5. An electric wire 16 Whose forward end is soldered to the contact lug 15 extends the length of guide rod 13 in a longitudinal slot 17 which is lined with insulating material and which communicates, by a bore directed toward the axis of the rod and lined with an insulating tube 18, with the seat containing the contact lug 15. The rear or lower end of the wire 16 passes through the head 13a in an axial bore lined with an insulating tube 19 and is pressed by a set screw 20 screwed into an insulating sleeve 21 against the interior wall of a contact 22 disposed in the insulating sleeve 21. The contact 22 is connected by a conductor 23 to the positive pole of a current source 25, while the head 13a is connected by a conductor 24 to the negative pole of the said current source across a switch 2'6.
The rod 13 is disposed to guide the tube 2 on the one hand in the bore of the retaining ring 3 and on the other hand in the rear seat of the piston. According to another embodiment of the invention (not shown), the retaining ring 3 could be omitted and the rod 13, whose diameter would accordingly be somewhat less than that of the piston 5, would be freely slidably disposed directly in the tube 2.
The operation of the ballistic device is as follows:
The parts being in the position shown in FIG. 1, preparatory to launching the self-propelled projectile 1, 2, all that need be done is to close the switch 26 to establish an electric current between the contact lug 15 and the contact 11 so that a circuit is completed, on the one hand, through contact 11, spring 12, rod 7, tail 9a and one end of the filament in capsule 9, and on the other hand, through head 13a, rod 13, piston 5, ring 10, capsule 9 and the other end of the filament in capsule 9. The filament in capsule 9 will thus be. brought to incandescence by electric resistance heating and will fire the primer, which in turn will rlire the launching charge 4 which explodes, exerting on the piston 5 maintained fixed by the guide rod 13 a pressure which is initially quite great. Under the influence of this pressure, the tube 2 secured to the head 1 of the projectile is projected forwardly in the direction of the arrow F in FIG. 2, while the piston 5 is forced against the forward end of rod 13; and when the tube 2 leaves the rod 13, as seen in FIG. 2, the piston 5 will be retained in the rear end of tube 2 by the retaining ring 3. The tight fit of piston 5 in tube 2 seals the rear end of tube 2 against the escape of gas. The length of the tube 2 is so adjusted that the acceleration of the projectile with respect to the guide rod 13 will be practically over when the tube leaves the guide rod 13. The full acceleration of the projectile therefore corresponds substantially to the practically total combustion of the explosive charge 4.
Although the present invention has been described and illustrated in connection with a preferred embodiment, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this artvwill readily understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.
Having described my invention, I claim:
1. In a ballistic device comprising a projectile and a launcher for that projectile, the projectile comprising a rearwardly extending tube containing a combustible charge sealed in the tube by means of a piston, the launcher comprising a guide rod that extends forwardly into the tube and bears against the rear of the piston, and electrical ignition means for the launching charge; the improvement in which the piston is force fitted into the tube, an ignition capsule disposed at least in part in a recess of the piston adjacent the charge with a shoulder of the capsule resting on the bottom of the recess, the piston having an axial bore therein, a pin of insulating material disposed in the bore, conductor means extending along the piston and through said insulating pin and electrically interconnecting a source of electricity in said ignition capsule to ignite a primer in said capsule when said conductor means is electrically charged, said guide rod having a recess in its forward end, insulating material lining the last-named recess, said conductor means comprising a conductive metal plug disposed in said last-named recess and surrounded by said insulating material, and electrically conductive means extending through said insulating pin and releasably electrically contacting said plug for connecting said plug electrically with said primer when the rear of the piston bears against the forward end of said guide rod.
2. A ballistic device as claimed in claim 1, the rstmentioned said recess being disposed on the axis of said piston and opening in an axial direction away from said guide rod.
3. A ballistic device as claimed in claim 1, said means extending through said insulating pin including means slidably disposed in the pin, and spring means urging said slidably disposed means against and into electrical contact with said plug.
4. A ballistic device as claimed in claim 1, said conductor means including an electric wire extending lengthwise within but insulated from said guide rod.
5. A ballistic device as claimed in claim 1, said conductor means including an incandescent wire in contact with said primer.
6. A ballistic device as claimed in claim 4, in which said wire is disposed in a longitudinal groove in said guide rod, said groove being lined with insulating material.
7. A ballistic device as claimed in claim '6, said wire extending from said groove through a passageway directed inwardly toward the axis of the guide rod and being electrically secured to a contact disposed axially of but electrically insulated from the rear end of said guide rod.
8. A ballistic device as claimed in claim 7, said wire extending inwardly from said groove toward the axis of said guide rod at the forward end of said guide rod and being in electrical contact with a plug that is disposed in but electrically insulated from the forward end of said guide rod.
References Cited UNITED STATES PATENTS 1,034,160 7/1912 Starkweather 102-46 1,347,125 7/1920 Schneider 89-1.3 2,931,299 4/1960 Sokolowski 102-46 X 3,068,755 12/1962 `lohnstone et al. 89-1.3 3,134,330 5/1964 Batou 89-1.3 X 3,365,828 1/1968 Badali et al 421 F SAMUEL W. ENGLE, Primary Examiner U.S. Cl. X.R.
42-1 F; 89-28; IGZ-46, 49.1