CONTROL APPARATUS
United States Patent 3636880
A velocity decay actuated self-destruct mechanism for use with stabilized projectiles. Dynamic pressure against a nose cap due to movement of the projectile through a fluid medium is balanced by spring pressure from within the ogive of the projectile. Movement of the nosepiece as the spring pressure overcomes the dynamic pressure causes self-destruct of the projectile.
US Patent References:
Percussion fuse for projectiles
Denoix - May 1941 - 2243621
Combined fuse
Weiss - January 1950 - 2493278
Delay arming fuze
Berzof et al. - September 1953 - 2651993
Delay fuze for spinning projectiles
Tlam - June 1967 - 3326132
Percussion fuse for projectiles
Denoix - May 1941 - 2243621
Combined fuse
Weiss - January 1950 - 2493278
Delay arming fuze
Berzof et al. - September 1953 - 2651993
Delay fuze for spinning projectiles
Tlam - June 1967 - 3326132
Application Number:
04/783581
Publication Date:
01/25/1972
Filing Date:
12/13/1968
View Patent Images:
Export Citation:
Assignee:
Honeywell Inc. (Minneapolis, MN)
Primary Class:
Other Classes:
102/266
International Classes:
F42C9/16; F42C14/00; F42C15/196; F42C9/00; F42C15/00; F42C15/24; F42C15/04; F42C15/26
Field of Search:
102/71,80
Primary Examiner:
Borchelt, Benjamin A.
Assistant Examiner:
Webb, Thomas H.
Claims:
Many modifications and embodiments are possible within the scope and spirit of the present invention. I wish to be limited only by the appended claims wherein I claim
1. An improved self-destruct mechanism for use with a flight-stabilized projectile having a detonator disposed within an ogive, wherein the improvement comprises:
2. The improved self-destruct mechanism of claim 1 wherein:
3. A fuse for a spinning projectile subject to decreasing velocity after launch due to drag forces acting on said projectile comprising delayed arming impact means having a firing pin and a detonator for delayed arming and for firing of a munition subject of setback, spin, and impact, in combination with velocity-responsive apparatus of claim 3 having movable means for receiving a drag force dependent on relative velocity with respect to a fluid medium, spring means for acting on said movable means in opposition to said drag force and actuator means operatively connected to said firing pin, for providing a mechanical output in response to movement of said movable means by said spring means in opposition to said drag force, whereby said mechanical output fires said detonator after the velocity of said projectile drops to a predetermined level.
4. An improved velocity-dependent self-destruct mechanism for use with a flight-stabilized projectile having a detonator disposed within an ogive, wherein the improvement comprises:
1. An improved self-destruct mechanism for use with a flight-stabilized projectile having a detonator disposed within an ogive, wherein the improvement comprises:
2. The improved self-destruct mechanism of claim 1 wherein:
3. A fuse for a spinning projectile subject to decreasing velocity after launch due to drag forces acting on said projectile comprising delayed arming impact means having a firing pin and a detonator for delayed arming and for firing of a munition subject of setback, spin, and impact, in combination with velocity-responsive apparatus of claim 3 having movable means for receiving a drag force dependent on relative velocity with respect to a fluid medium, spring means for acting on said movable means in opposition to said drag force and actuator means operatively connected to said firing pin, for providing a mechanical output in response to movement of said movable means by said spring means in opposition to said drag force, whereby said mechanical output fires said detonator after the velocity of said projectile drops to a predetermined level.
4. An improved velocity-dependent self-destruct mechanism for use with a flight-stabilized projectile having a detonator disposed within an ogive, wherein the improvement comprises:
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to fuses for ordnance projectiles and, more particularly, stabilized projectile fuses having a velocity-responsive self-destruct feature.
2. Description of the Prior Art
Self-destruct mechanisms to detonate a charge within a projectile if impact does not occur within a predetermined flight distance are common in the prior art. Popular mechanisms for effecting self-destruct have employed spin decay in spin-stabilized projectiles to indicate the distance covered after launch. Another commonly used indicator for flight distance is a simple time delay. Time delay devices such as mechanical timers, gas generators, electronic timers, and pyrotechnic delay arrangements are commonly used to initiate the explosive projectile after a predetermined time period in the absence of impact.
For small caliber projectiles with slow spin rates, the spin rate is a less satisfactory indication of distance covered and the point at which self-destruct should be initiated. In a nonspinning or low-spin projectile, spin decay is thus not a reliable indication of flight distance.
Timing devices are necessarily complex to attain a reliable indication of actual flight distance for self-destruct purposes. In addition, timers of the electronic variety require a source of power which is also undesirable in small caliber munitions.
It is an object of the present invention to provide an improved self-destruct mechanism which is responsive to the velocity decay of a projectile.
SUMMARY OF THE INVENTION
The present invention pertains to the use of dynamic pressure on the nose of a moving projectile to indicate velocity decay and initiate self-destruct of the projectile. The invention provides an entirely mechanical mechanism suitable for use with small caliber munitions.
A movable nose cap is slidably engaged in an opening in the nose of a projectile where it is subject to dynamic pressure due to movement of the projectile through a fluid medium. Drag forces on the nose cap at arming overbalance a spring force from within the ogive tending to push the nose cap forward. As the velocity of the projectile decreases, drag pressures also decrease and the spring pressure exerted from within the ogive overcomes the dynamic pressure pushing the nose cap forward and releasing a striker to actuate a detonator.
The preferred embodiment of the invention utilizes a delay fuse for spinning projectiles of the type shown in U.S. Pat. No. 3,326,132, issued to E. W. Tlam and assigned to the assignee of the present invention. The Tlam device provides delayed arming for a projectile subject to setback force upon launch, rotational force during flight, and impact force at the termination of the flight. The projectile fuse shown has all the features of the Tlam device with, in addition, the self-destruct mechanism of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a fuse embodiment utilizing the self-destruct mechanism of the present invention.
FIG. 2 is an exploded view of the fuse of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring jointly to FIGS. 1 and 2, an ogive 1 has a hollowed-out portion of cylindrical cross section of varying diameters and a cylindrical opening to the nose. The inner wall of the cylindrical opening defines a circular groove 7.
A nose cap 16, having a cylindrical center cavity and a tubular tail extension with four holes 17 through the walls of the extension in a circumferential pattern, is slidably engaged in the cylindrical nose opening of ogive 1. An annular seal 20 is positioned between the nose cap 16 and the ogive 1. Four detent balls 19 are disposed within the four holes 17 holding a plunger 21 urged by a spring 22 within the nose cap. The nose cap is secured to the ogive by a setback weight 18 which is press fitted onto the tubular extension of nose cap 16 within the ogive. A flange is formed on the end of the extension after the nose cap is secured.
A cylindrical piston 12, having a one-way seal 13 around its periphery, a centrally positioned striker 11, and a porous restrictor 15 located in an axial port in the piston, is disposed within a cylindrical cross section hollowed portion of ogive 1. The seal 13 is oriented to allow easy movement of the striker toward the base of the projectile while movement in the other direction requires that displaced air travel through porous restrictor 15.
A cylindrical body assembly 4 holds a spring 14 against the base of piston 12 urging the striker 11 against the plunger 21. Contained within the body assembly 4 is a diametrically pivoted, cylindrical rotor 5 carrying a stab detonator 8. The rotor 5 further has a detent 6 and centrifugal weights 9a, 9b, and 9c. The rotor 5 is locked in a fixed position relative to body member 4 by the end of striker 11.
A deformable setback washer 10 is held against the end of body member 4 by a base 2 containing a lead assembly 3. The base 2 has an opening to transfer detonation of the lead assembly to the main charge (not shown) in proximity to base 2.
Detent balls 19 retain the plunger 21 urged by spring 22 within nose cap 16. The circular groove 7 in the inner wall of the cylindrical opening is located slightly ahead of the detent ball location and is of such size to permit the balls 19 to move radially outward when the nose cap 16 moves forward, thereby releasing plunger 21.
OPERATION
With the exception of the self-destruct mechanism, operation of the fuse is described in the Tlam patent 3,326,132.
Upon setback, the setback washer 10 collapses and setback weight 18 slides rearward down the tubular extension of nose cap 16 until it contacts the flanged end of the extended portion.
As the body member 4 compresses setback washer 10, piston assembly 12 is carried rearward by the inertia of striker 11. The one-way seal 13 on piston member 12 allows easy travel of the piston to the rear of the ogive. After setback, the spring 14 urges the piston 12, carrying the striker 11, forward with a time delay determined by the nature of restrictor 15. As the piston 12, carrying striker 11, moves toward the nose of the ogive due to the pressure exerted by spring 14, the air displaced ahead of the piston 12 must pass through the port in the piston 12. The time delay is controlled by the port size and the restrictor 15 material. As the piston 12 carries the striker 11 forward, the rotor 5 within body member 4 is released and, due to spinning of the projectile, is rotated into an armed position with the stab detonator in line with the striker and an output hole in the bottom of body member 4. A cylindrical detent 6 locks the rotor in the armed position.
The fuse is now in the armed position. Three functioning actions are now possible:
1. Hard target impact--collapse of the nose cap and ogive drives the striker 11 aft into the stab detonator 8 providing a "super quick" function.
2. Graze or soft target--inertia action drives the body assembly 4 forward where the stab detonator impacts the firing pin 11 providing an "inertia" function.
3. Self-destruct--after a flight of predetermined length without impact as determine by the mechanism design, piston spring 14 drives the piston assembly 12 and the nose cap 16 against the dynamic pressure exerted on the nose cap. The nose cap slides forward causing the four ball detents 19 to release the spring-loaded plunger 21, thus forcing striker 11 engaged in piston 12 into stab detonator 8 and providing a self-destruct function.
An analysis of the preferred embodiment of the invention shown in FIGS. 1 and 2 illustrates the design considerations for triggering of the self-destruct mechanism. The nose cap 16 will be pushed forward by the spring 14 when the force of spring 14 exceeds the combined friction and dynamic drag force acting on the nose cap and plunger. The dynamic drag force acts on the nose cap with a force dependent on projectile velocity, drag coefficient, drag reference area, and the medium density. The frictional force is dependent on the number of balls, the static friction coefficient between the balls and the inner wall of the cylindrical passageway in ogive 1, and the forces acting on each ball detent normal to the axis of the projectile.
1. Field of the Invention
The present invention pertains to fuses for ordnance projectiles and, more particularly, stabilized projectile fuses having a velocity-responsive self-destruct feature.
2. Description of the Prior Art
Self-destruct mechanisms to detonate a charge within a projectile if impact does not occur within a predetermined flight distance are common in the prior art. Popular mechanisms for effecting self-destruct have employed spin decay in spin-stabilized projectiles to indicate the distance covered after launch. Another commonly used indicator for flight distance is a simple time delay. Time delay devices such as mechanical timers, gas generators, electronic timers, and pyrotechnic delay arrangements are commonly used to initiate the explosive projectile after a predetermined time period in the absence of impact.
For small caliber projectiles with slow spin rates, the spin rate is a less satisfactory indication of distance covered and the point at which self-destruct should be initiated. In a nonspinning or low-spin projectile, spin decay is thus not a reliable indication of flight distance.
Timing devices are necessarily complex to attain a reliable indication of actual flight distance for self-destruct purposes. In addition, timers of the electronic variety require a source of power which is also undesirable in small caliber munitions.
It is an object of the present invention to provide an improved self-destruct mechanism which is responsive to the velocity decay of a projectile.
SUMMARY OF THE INVENTION
The present invention pertains to the use of dynamic pressure on the nose of a moving projectile to indicate velocity decay and initiate self-destruct of the projectile. The invention provides an entirely mechanical mechanism suitable for use with small caliber munitions.
A movable nose cap is slidably engaged in an opening in the nose of a projectile where it is subject to dynamic pressure due to movement of the projectile through a fluid medium. Drag forces on the nose cap at arming overbalance a spring force from within the ogive tending to push the nose cap forward. As the velocity of the projectile decreases, drag pressures also decrease and the spring pressure exerted from within the ogive overcomes the dynamic pressure pushing the nose cap forward and releasing a striker to actuate a detonator.
The preferred embodiment of the invention utilizes a delay fuse for spinning projectiles of the type shown in U.S. Pat. No. 3,326,132, issued to E. W. Tlam and assigned to the assignee of the present invention. The Tlam device provides delayed arming for a projectile subject to setback force upon launch, rotational force during flight, and impact force at the termination of the flight. The projectile fuse shown has all the features of the Tlam device with, in addition, the self-destruct mechanism of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a fuse embodiment utilizing the self-destruct mechanism of the present invention.
FIG. 2 is an exploded view of the fuse of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring jointly to FIGS. 1 and 2, an ogive 1 has a hollowed-out portion of cylindrical cross section of varying diameters and a cylindrical opening to the nose. The inner wall of the cylindrical opening defines a circular groove 7.
A nose cap 16, having a cylindrical center cavity and a tubular tail extension with four holes 17 through the walls of the extension in a circumferential pattern, is slidably engaged in the cylindrical nose opening of ogive 1. An annular seal 20 is positioned between the nose cap 16 and the ogive 1. Four detent balls 19 are disposed within the four holes 17 holding a plunger 21 urged by a spring 22 within the nose cap. The nose cap is secured to the ogive by a setback weight 18 which is press fitted onto the tubular extension of nose cap 16 within the ogive. A flange is formed on the end of the extension after the nose cap is secured.
A cylindrical piston 12, having a one-way seal 13 around its periphery, a centrally positioned striker 11, and a porous restrictor 15 located in an axial port in the piston, is disposed within a cylindrical cross section hollowed portion of ogive 1. The seal 13 is oriented to allow easy movement of the striker toward the base of the projectile while movement in the other direction requires that displaced air travel through porous restrictor 15.
A cylindrical body assembly 4 holds a spring 14 against the base of piston 12 urging the striker 11 against the plunger 21. Contained within the body assembly 4 is a diametrically pivoted, cylindrical rotor 5 carrying a stab detonator 8. The rotor 5 further has a detent 6 and centrifugal weights 9a, 9b, and 9c. The rotor 5 is locked in a fixed position relative to body member 4 by the end of striker 11.
A deformable setback washer 10 is held against the end of body member 4 by a base 2 containing a lead assembly 3. The base 2 has an opening to transfer detonation of the lead assembly to the main charge (not shown) in proximity to base 2.
Detent balls 19 retain the plunger 21 urged by spring 22 within nose cap 16. The circular groove 7 in the inner wall of the cylindrical opening is located slightly ahead of the detent ball location and is of such size to permit the balls 19 to move radially outward when the nose cap 16 moves forward, thereby releasing plunger 21.
OPERATION
With the exception of the self-destruct mechanism, operation of the fuse is described in the Tlam patent 3,326,132.
Upon setback, the setback washer 10 collapses and setback weight 18 slides rearward down the tubular extension of nose cap 16 until it contacts the flanged end of the extended portion.
As the body member 4 compresses setback washer 10, piston assembly 12 is carried rearward by the inertia of striker 11. The one-way seal 13 on piston member 12 allows easy travel of the piston to the rear of the ogive. After setback, the spring 14 urges the piston 12, carrying the striker 11, forward with a time delay determined by the nature of restrictor 15. As the piston 12, carrying striker 11, moves toward the nose of the ogive due to the pressure exerted by spring 14, the air displaced ahead of the piston 12 must pass through the port in the piston 12. The time delay is controlled by the port size and the restrictor 15 material. As the piston 12 carries the striker 11 forward, the rotor 5 within body member 4 is released and, due to spinning of the projectile, is rotated into an armed position with the stab detonator in line with the striker and an output hole in the bottom of body member 4. A cylindrical detent 6 locks the rotor in the armed position.
The fuse is now in the armed position. Three functioning actions are now possible:
1. Hard target impact--collapse of the nose cap and ogive drives the striker 11 aft into the stab detonator 8 providing a "super quick" function.
2. Graze or soft target--inertia action drives the body assembly 4 forward where the stab detonator impacts the firing pin 11 providing an "inertia" function.
3. Self-destruct--after a flight of predetermined length without impact as determine by the mechanism design, piston spring 14 drives the piston assembly 12 and the nose cap 16 against the dynamic pressure exerted on the nose cap. The nose cap slides forward causing the four ball detents 19 to release the spring-loaded plunger 21, thus forcing striker 11 engaged in piston 12 into stab detonator 8 and providing a self-destruct function.
An analysis of the preferred embodiment of the invention shown in FIGS. 1 and 2 illustrates the design considerations for triggering of the self-destruct mechanism. The nose cap 16 will be pushed forward by the spring 14 when the force of spring 14 exceeds the combined friction and dynamic drag force acting on the nose cap and plunger. The dynamic drag force acts on the nose cap with a force dependent on projectile velocity, drag coefficient, drag reference area, and the medium density. The frictional force is dependent on the number of balls, the static friction coefficient between the balls and the inner wall of the cylindrical passageway in ogive 1, and the forces acting on each ball detent normal to the axis of the projectile.