US 3205821 A
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p 1965 ABESCAT ETAL 3, ,8
PROJEGTILE PROPULSIVE SYSTEM WITH PRESSURE-ACTUABLE ARMING- MEANS Filed July 9, 1965 2 Sheets-Sheet 1 150mm HBESCAT 71400055 BLAND/N JZ-AN (iv/0r EM/L E 6 r4 UFF ra-WWW HTTORNE Y5 Sept. 14, 1965 ABESCAT ETAL 3,205,321
PROJECTILE PROPULSIVE SYSTEM WITH PRESSURE-ACTUABLE Filed July 9, 1963 ARMING MEANS 2 Sheets-Sheet 2 l/VVE/VTO/FS' A 50 04 0 4555047- Aca U65 5.4 4/1/0/A/ J54 00/4 407' fM/A 5 5 TAUFF mAVQm ATTORNEYS United States Patent 912,613 Claims. (Cl. 102-49) This invention relates to propulsive charges for weapons having detonatable explosivecharges. It relates particularly to safety systems for use in connection with propulsive charges for self-propelled military projectiles, such as rockets.
It is necessary for such self-propelled projectiles which carry explosive Charges to include one or more internal safety devices to prevent the explosive charge from being detonated before the projectile is sufiiciently far from the launching station; damage to the personnel or equipment of the launching station or adjacent friendly areas is thus avoided if the projectile goes oif course or its detonation system is prematurely actuated. Projectiles may be fired from fixed ground stations or from moving vehicles, which may be near the military front or some distance behind it, and an appropriate safety delay must be imposed in these various circumstances; in the case of a weapon fired from an aircraft, the charge hould be prevented from exploding until the projectile is a safe distance from the aircraft, having regard to the course of flight of the aircraft under the particular operational conditions.
It is an object of the invention to provide a simple safety device for use in self-propelled projectiles having an explosive charge, a detonator for the explosive charge and a pressure-actuable device for arming the detonator. A propulsion unit for use in the combustion chambers of such a projectile compiises, according to the invention, a combustible propulsion charge, and at least one passage leading from a point within the charge to a part of the projectile gastightly separated from the combustion front and communicating with the pressure-actuable device, whereby combustion gases are enabled to pass to such device when the combustion front has reached the mouth of the passage.
Preferably more than one passage is provided; the passages should be arranged so that the advance of the combustion front is not affected, and they are thus preferably within thermally insulated tubes arranged at the periphery of the combustion charge. The invention may be utilized for the arming after a predetermined delay of any pressure-actuable device, which may be situate in any convenient part of the projectile where it can be connected to the detonator. When the propulsive charge has burnt down to reveal the end of the tube, the pressure of the combustion gases is transmitted through the tube to the arming device.
One preferred embodiment of the invention will be described with reference to the accompanying drawing, in which;
FIG. 1 is a vertical section of a propulsion unit,
FIG. 2 is a cross-section along the line IIII of FIG. 1, and
FIG. 3 is a sectional view similar to FIG. 1 showing the explosive charge and firing cap of the projectile and the detonator for striking the cap to explode a charge.
Referring to the drawings, the propulsive charge I is generally cylindrical in shape; one end In is flat and con- "ice stitutes the combustion face, which is rearmost in flight. The charge is covered, except on its combustion face, by a thermally insulating and protective layer 2, which is shaped externally to fit a particular combustion chamber, and is illustrated with a forward end of spherical shape for this purpose. Three small-bore copper tubes 3 debouch at the forward end of the charge, and their other ends 315 are all the same distance from the combustion face, and covered by the charge; these tubes are embedded throughout their length in the insulating layer 2, which is formed into an additional layer 2a around them, so that the hot gases which ultimately pass down the tubes are prevented from igniting the adjacent charge ahead of the normal combustion front.
In use, the propulsion unit is placed in the combustion chamber 6 (shown in broken lines) of a self-propelled projectile. A gasket 4 of synthetic plastic is arranged between the forward end of the charge and the closed end of the chamber, so that a cavity 7 is formed into which the ends 3a of the tubes debouch; this cavity is connected by an opening 5 to a device for the arming of the detonator for the explosive charge. Such device can be a piston maintained at rest by a calibrated spring, by a rupturable pin or other element, or by any other mechanism which can be released by a known force, and it can operate by removing a shutter from between the detonator and explosive charge, by moving the detonator itself, or by other known means. By way of example there has been shown in FIG. 3 a device for arming the detonator for the explosive charge. A striker 8 carrying a firing pin 8a is held in an inactive position by a bolt 9 which is itself held in fixed position by a metallic shear pin 10. While a specific device has been illustrated for arming the detonator for the explosive charge, the detonator may be armed by other means, such as those already mentioned.
When the charge is ignited at the face In, the combustion gases are generated and escape from the rear of the chamber, and the combustion front advances, and until it reaches the plane in which the ends 312 of the tubes lie, the pressure in the cavity 7 is the same as that prevailing before the combustion (i.e the ambient atmospheric pressure). When the combustion front reaches the mouth or end 36 of the tube, the combustion gases pass down the tubes 3 and the pressure in the cavity 7 rises until it is equal to that produced in the front of the chamber; the gases pass through the opening 5 to the arming device, e.g. the lower end of the bolt 9, and actuate it by their pressure. Under this action, the shear pin 10 is ruptured, the bolt 9 is displaced upwardly unbolting the striker 8 which, upon impact of the projectile, will be free to move the deceleration due to shock, to strike the percussion cap with the firing pin 8a carried thereby and explode the explosive charge of the projectile. The detonator is thus armed according to the method chosen, adapted to the nature of the elements of the explosive charge. The arming circuit being gastight, the pressure rise is established with the passage of a very small amount of cornbustion gases, so that heating of the tubes and of the arming device is negligible.
The resistance of the shear pin 10 or other system opposing the movement of the bolt 9 is regulated so that the arming of the detonator is only achieved at a predetermined minimum pressure. Consequently, if the propulsive charge does not become sufiiciently ignited to give adequate propulsion, but smoulders slowly over a long period then, even though the ends of the tubes may eventually be uncovered, there will not be sufiicient gas pressure to actuate the mechanism for arming the detonator. If the combustion is correctly initiated but ceases prematurely, or the propulsion unit is prematurely ruptured before the end of the selected delay preiod, the ends of the tubes will not be uncovered and there will be no arming of the fuse. The arming of the detonator only takes place if the propulsion system of the projectile has functioned properly during the selected delay period and, consequently, when the projectile ha travelled the corresponding distance, the delay being proportional to the thickness of the layer of propulsive charge to be burnt before the ends 3b of the tubes are uncovered.
The safety system according to the invention can be combined with other systems based on other principles (e.g. autorotation or acceleration) so that the safety of the projectile is ensured by two or more independent or interdependent series of safety systems.
The tubes need not be of copper, but may be of other metals, or of synthetic plastics material, or they may be simple orifices made in the charge and provided with an inhibitory covering.
1. A propulsion unit for use in the combustion chamber of a self-propelled projectile having an explosive charge, a detonator for said charge, a pressure-actuable device for arming the detonator, and a combustion chamber, in which the unit comprises a combustible propulsion charge fitting into the combustion chamber, and at least one passage having a mouth disposed at a point within the chamber normally covered by said charge leading to a part of the projectile gastightly separated from the combustion front and communicating with the pressureactuable device, whereby combustion gases are enabled to pass to such device when the combustion front has reached the mouth of the passage.
2. A propulsion unit according to claim 1, in which the part of the projectile separated from the combustion front is a forward portion of the combustion chamber.
3. A propulsion unit according to claim 2, which includes a thermally insulating and protective layer which encloses the propulsive charge except on its ignition face, and in which the passage is constituted by a tube running along the periphery of the propulsion chamber and separated from the propulsive charge by the insulating layer.
4. A propulsion unit according to claim 3, in which the tube is formed of metal.
5. A propulsion unit according to claim 3, in which the tube is formed of synthetic plastics material.
References Cited by the Examiner UNITED STATES PATENTS 695,57 8 3 /02 McIntyre 102-49 2,145,507 1/39 Denoix 10249 2,918,870 12/59 Meister 102-49 3,049,080 8/62 Schermuly 10234.4
BENJAMIN A. BORCHELT, Primary Examiner.
SAMUEL FEINBERG, Examiner.