MULTIPLE INPUT ARMING MECHANISM
United States Patent 3626853
An arming mechanism for a spinning projectile, whereby said mechanism is responsive only to the simultaneous existence of both a predetermined centrifugal force and a predetermined force caused by the airflow passing the projectile as it travels through the air. First means responding to the force caused by the airflow and second means responding to the centrifugal force unite to produce a driving force within the arming mechanism due to relative motion between the first means and the second means. The driving force is transmitted through the second means for moving a detonator from a safety position to an armed position.
US Patent References:
Clockwork movement for a projectile
Kuhn - September 1955 - 2718850
Delayed arming device for projectiles
McCaslin et al. - August 1949 - 2479851
Centrifugal safety device for a projectile fuze
Burrell - August 1959 - 2900908
Barometric munition
Paulson et al. - February 1965 - 3170398
Clockwork movement for a projectile
Kuhn - September 1955 - 2718850
Delayed arming device for projectiles
McCaslin et al. - August 1949 - 2479851
Centrifugal safety device for a projectile fuze
Burrell - August 1959 - 2900908
Barometric munition
Paulson et al. - February 1965 - 3170398
Application Number:
05/006255
Publication Date:
12/14/1971
Filing Date:
02/27/1970
View Patent Images:
Export Citation:
Assignee:
Honeywell Inc. (Minneapolis, MN)
Primary Class:
Other Classes:
102/244
International Classes:
F42C15/188; F42C15/22; F42C15/295; F42C15/00; F42C15/26
Field of Search:
102/70,79,80,71,81,81.2,86
Primary Examiner:
Engle, Samuel
Claims:
I claim as my invention
1. An arming mechanism for use in a spinning projectile having an axis of rotation comprising:
2. The mechanism of claim 1 wherein said first means comprises:
3. The mechanism of claim 2 wherein said second means comprises:
4. The mechanism of claim 3 wherein said arming means comprises a rotor containing a detonator, said rotor being rotatably mounted within said housing.
5. The mechanism of claim 4 and a spring projected lockweight mounted within said housing such that said lockweight normally holds said rotor in the safety position until a predetermined centrifugal force causes said lockweight to retract, thereby allowing movement of said rotor.
6. An arming mechanism for use in a spinning projectile having an axis of rotation comprising:
7. The mechanism of claim 6 wherein said first means comprises:
1. An arming mechanism for use in a spinning projectile having an axis of rotation comprising:
2. The mechanism of claim 1 wherein said first means comprises:
3. The mechanism of claim 2 wherein said second means comprises:
4. The mechanism of claim 3 wherein said arming means comprises a rotor containing a detonator, said rotor being rotatably mounted within said housing.
5. The mechanism of claim 4 and a spring projected lockweight mounted within said housing such that said lockweight normally holds said rotor in the safety position until a predetermined centrifugal force causes said lockweight to retract, thereby allowing movement of said rotor.
6. An arming mechanism for use in a spinning projectile having an axis of rotation comprising:
7. The mechanism of claim 6 wherein said first means comprises:
Description:
BACKGROUND OF THE INVENTION
This invention is an improvement in the field of mechanical arming devices for spinning projectiles.
Presently, many spinning projectiles are armed by mechanisms activated only by the centrifugal force created by the spin of the projectile during its flight. However, for certain spinning projectiles dispensed from airplanes, malfunctions in the dispensing mechanism can occur during the airplane's takeoff or landing, thereby releasing the spin-to-arm projectiles along the runway. In such a situation, the conventional spin activated arming apparatus could experience sufficient centrifugal force to arm the weapon thereby creating a danger of detonation in friendly territory. This danger is avoided by the present invention, because it requires a predetermined translational airflow about the projectile while the projectile is spinning before the arming mechanism is activated. Since the ordinary takeoff and landing speeds of an airplane are below the speed required to create the necessary airflow for activation of the present arming mechanism, an accidental dispersement of spin-to-arm projectiles would not result in the release of armed weapons.
SUMMARY OF THE INVENTION
The present invention is an arming mechanism for spinning projectiles. When the spinning projectile is dispensed, the arming mechanism does not respond until there exists simultaneously a predetermined centrifugal force due to the rotation of the projectile and a predetermined force caused by the airflow passing the projectile as it travels through the air.
A driving force is produced within the arming mechanism by the concerted action of a first means responding to the force caused by the airflow and a second means responding to the centrifugal force. When both forces exist simultaneously, the second means engages the first means by way of a gear drive means. The driving force is the result of the relative motion between the responding first means and second means. An arming means is moved from a safety position to an armed position by the driving force. Should either force fail before the arming means reaches the armed position, the arming means returns to the safety position.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a preferred embodiment of the arming mechanism in an unarmed or safety position;
FIG. 2 is a plan view of the preferred embodiment of the arming mechanism in an armed position; and
FIG. 3 is a sectional view of the preferred embodiment taken along the line 3--3 of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 and 3, a housing 1 by which the arming mechanism within a projectile 2 having an axis of rotation 5, is a cylindrical container open at one end and closed at the other by a base plate 3. A vane shaft 4 is rotatably mounted perpendicular to base plate 3 and extends axially from base plate 3 through an opening in projectile 2. Vane shaft 4 is aligned with the axis of rotation 5 of projectile 2. A vane 5 in the shape of a flat rectangular piece of rigid material is attached by one edge along vane shaft 4 external to projectile 2. A rotor pin 7 is inserted into an axial bore 8 in vane shaft 4 such that rotor pin 7 is contained within housing 1. A gear drive 9, which may be made of rubber or other semihard material, has a flat circular shape with a smooth circumference and is placed on rotor pin 7 adjacent the inside surface of base plate 3. Gear drive 9 is fixed to rotate with vane shaft 4.
As viewed in FIG. 1, a triangularly shaped rotor 10 is mounted at one corner to rotor pin 7 such that rotor 10 may rotate about axis of rotation 5 of projectile 2. Rotor 10 is free to rotate with respect to both rotor pin 7 and gear drive 9. Other arming means having a safety position and an armed position could be used in place of rotor 10.
A detonator 11 is carried by rotor 10 and oriented for firing in the direction parallel to axis of rotation 5. Detonator 11 may be a small quantity of explosive which explodes upon impact with a firing pin to ignite a greater quantity of explosive.
A detent rod 12 is mounted on one side of rotor 10 such that detent rod 12 is perpendicular to base plate 3. A detent cap 13 is slideably mounted to the end of detent rod 12 adjacent base plate 3. A detent spring 14 is placed on detent rod 12 and is compressed between rotor 10 and detent cap 13, thereby forcing detent cap 13 against base plate 3.
A channel 15 for containing and controlling the movement of detent cap 13 is cut into the interior surface of base plate 3. Channel 15 is shaped to conform exactly to the arc described by detent cap 13 as rotor 10 rotates about rotor pin 7. Channel 15 restricts the degree of rotation of rotor 10, because the clockwise rotation of rotor 10 as viewed in FIG. 1 terminates at an arming lock hole 16 in base plate 3. Arming lock hole 16 is of sufficient depth and diameter to allow detent cap 13 to fit securely within it. The location of arming lock hole 16 is such that detonator 11 is aligned with a detonator passage 17 when detent cap 13 is seated in arming lock hole 16. Detonator passage 17 is a circular hole in base plate 3 and provides the only way in which detonator 11 can be struck by a firing pin. This position of detonator 11 constitutes the armed position of the mechanism and is illustrated in FIG. 2. As viewed in FIG. 1, channel 15 need only extend to the left of arming lock hole 16 sufficiently to insure that no part of detonator 11 is exposed to detonator passage 17 when rotor 10 is rotated fully counterclockwise. When detent cap 13 is in that position in channel 15, the mechanism is in the unarmed or safety position which is illustrated in FIG. 1.
A rotor return spring 18 is connected between detent rod 12 and a retaining rod 19 which is attached to base plate 3. Retaining rod 19 is located near channel 15 such that rotor return spring 18 is extended by any clockwise movement of rotor 10 from its safety position as viewed in FIG. 1.
A lockweight 20 is a hook-shaped weight pivotally mounted to the interior surface of the base plate 3. Lockweight 20 pivots about an axis parallel to axis of rotation 5 and as shown in the safety position in FIG. 1 catches rotor 10, thereby preventing any clockwise movement of rotor 10. A lockweight spring 21 is compressed between lockweight 20 and housing 1, whereby lockweight spring 21 must be further compressed before lockweight 20 releases rotor 10.
A gear train 22 includes four gears which perform a gear speed reduction due to their alignment. The base of gear train 22 is a lower plate 23 pivotally mounted parallel to base plate 3 by a shaft 24. A spacer 25 is positioned on shaft 24 between baseplate 3 and lower plate 23 allowing lower plate 23 to move freely with respect to base plate 3.
A gear 26 is rotatably mounted on shaft 24. A gear drive 27, which may be made of rubber or other semihard material, has a flat circular shape with a smooth circumference and is rotatably mounted on shaft 24. Gear drive 27 has a diameter smaller than the diameter of gear 26 and is attached to gear 26 so as to function as a pinion for gear 26. A gear 28 having the same dimensions as gear 26 is rotatably mounted on shaft 24 adjacent gear drive 27.
A shaft 29 is mounted on lower plate 23 parallel to shaft 24. A gear 30 having the same dimensions as gear 26 is rotatably mounted on shaft 29 adjacent lower plate 23. A gear drive 31 having the same dimensions as gear drive 27 is rotatably mounted on shaft 29 and attached to gear 30 so as to function as a pinion for gear 30. The location of shaft 29 is such that gear 26 engages gear drive 31. Sufficient friction exists between the semihard surface of gear drive 31 and the teeth of gear 26 to eliminate the need for teeth in the circumference of gear drive 31. Therefore, the engagement of gear drive 31 and gear 26, as with subsequent gears and gear drives, amounts to mere contact and not the meshing of gear teeth. A gear 32 having the same dimensions as gear 26 is rotatably mounted on shaft 29 and engages gear drive 27 on shaft 24. A gear drive 33 having the same dimensions as gear drive 27 is rotatably mounted on shaft 29 and attached to gear 32 so as to function as a pinion for gear 32. Gear drive 33 engages gear 28 on shaft 24. An upper plate 34, identical to lower plate 23, is rigidly attached to lower plate 23 by rods 35, thereby forming a structure which contains the gears and gear drives mounted on shaft 24 and shaft 29. This completes the structure of gear train 22. Variations in the structure of gear train 22 may be made without altering its function which is to perform a gear speed reduction between gear 30 and gear 28.
A counterweight 36 is rigidly attached to gear train 22 such that the center of gravity of the combination of counterweight 36 and gear train 22 may rotate clockwise about shaft 24, as viewed in FIG. 1, as a result of a centrifugal force created by the rotation of projectile 2 about axis of rotation 5. The clockwise rotation of the combination of counterweight 36 and gear train 22 about shaft 24 causes gear 30 to engage or come into contact with gear drive 9. A counterweight spring 37 is compressed between counterweight 36 and housing 1 such that counterweight spring 37 normally holds the combination of counterweight 36 and gear train 22 in its full counterclockwise position whereby gear 30 does not engage gear drive 9. As viewed in FIG. 1, an arming wire 38 is connected between rotor 10 and a point near the circumference of gear 28, whereby any clockwise movement of gear 28 causes a clockwise movement of rotor 10.
It is apparent from the structure of the preferred embodiment of the arming mechanism that rotor 10 will not be moved to the armed position until there exists simultaneously a predetermined force caused by the airflow as projectile 2 travels through the air and a predetermined centrifugal force caused by the rotation of projectile 2 about axis of rotation 5. The centrifugal force causes gear 30 of gear train 22 which is rotating with projectile 2 to engage or come into contact with gear drive 9. Due to the force caused by the airflow, gear drive 9 is not rotating with projectile 2, and the resulting relative motion between gear train 22 and gear drive 9 causes the gears of gear train 22 to rotate about their own axes thereby advancing rotor 10 to the armed position.
OPERATION
The preferred embodiment was built for use in a spherical projectile designed for release from an airplane. The exterior design of the projectile is such that it causes the projectile to spin about axis of rotation 5 when the projectile is falling through the air. The arming mechanism is located within the projectile so that vane shaft 4 is aligned with axis of rotation 5 of the projectile. However, applicant's invention could be employed to arm any spinning projectile if vane shaft 4 is aligned with the axis of rotation of the projectile, and vane 5 is exposed to the airflow about the projectile as it travels through the air.
Operation of the preferred embodiment requires the simultaneous existence of a predetermined centrifugal force caused by the rotation of the projectile about axis of rotation 5 and a predetermined force caused by the airflow about the projectile as it travels through the air. As will be explained herein the mechanism can be designed to operate at various values of either force by adjusting the spring constant of the various springs within the mechanism. When the projectile containing the preferred embodiment of the arming mechanism achieves the spin rate necessary to produce the required centrifugal force, lockweight 20 rotates counterclockwise and the combination of counterweight 36 and gear train 22 rotates clockwise as viewed in FIG. 1. At this stage in the operation of the mechanism only rotor return spring 18 retains rotor 10 in its safety position. Also, as a result of the rotation of counterweight 36 and gear train 22, gear 30 within gear train 22 engages gear drive 9 on rotor pin 7. However, unless relative motion exists between gear 30 and gear drive 9, gear 30 will not rotate about its axis, and gear train 22 will not be activated. The creation of a relative motion is the function of vane 5 which is attached to vane shaft 4 and exposed to the airflow about projectile 2. When the required value of airflow exists about projectile 2, vane 5 is held in a fixed position parallel to the airflow. This is due to the force caused by the airflow acting against the surface of vane 5. Therefore, vane 5, vane shaft 4, rotor pin 7, and gear drive 9 are rotating with respect to the remaining structure of the arming mechanism which is rotating with projectile 2. Due to this relative motion between gear drive 9 and gear 30, gear 30 is rotated about its axis, and because of the structure of gear train 22, gear 26, gear 28, and gear 32 are rotated about their respective axes with a speed reduction occurring between successive gears. Since the circumference of gear 28 is linked to rotor 10 by arming wire 38, the rotation of gear 28 causes the rotation of rotor 10 until rotor 10 reaches the armed position as shown in FIG. 2. Rotor 10 is locked in the armed position by detent cap 13 being forced into arming lock hole 16 by detent spring 14. Detonator 11 is then in a position directly over detonator passage 17 for firing by a firing pin.
It is apparent that the value of the force caused by the airflow necessary to hold vane 5 stationary depends on the spring force of rotor return spring 18, which acts to prevent the rotation of the gears in gear train 22. Using the projectile as a reference, vane 5 and vane shaft 4 rotate with respect to the projectile when vane 5 is held in one position by the airflow. As such, vane shaft 4, by means of gear drive 9, rotates the gears of gear train 22 against the force of rotor return spring 18 which acts to prevent such rotation. If either input, centrifugal force, or the force caused by the airflow, fails before rotor 10 is locked into the armed position, rotor return spring 18 returns rotor 10 to its safety position.
The preferred embodiment described herein is merely one arrangement for applying the principles of the invention. It should be understood that other arrangements or modifications of the mechanism may be apparent to those skilled in the art, and such rearrangements or modifications would not alter the effect or scope of the invention.
This invention is an improvement in the field of mechanical arming devices for spinning projectiles.
Presently, many spinning projectiles are armed by mechanisms activated only by the centrifugal force created by the spin of the projectile during its flight. However, for certain spinning projectiles dispensed from airplanes, malfunctions in the dispensing mechanism can occur during the airplane's takeoff or landing, thereby releasing the spin-to-arm projectiles along the runway. In such a situation, the conventional spin activated arming apparatus could experience sufficient centrifugal force to arm the weapon thereby creating a danger of detonation in friendly territory. This danger is avoided by the present invention, because it requires a predetermined translational airflow about the projectile while the projectile is spinning before the arming mechanism is activated. Since the ordinary takeoff and landing speeds of an airplane are below the speed required to create the necessary airflow for activation of the present arming mechanism, an accidental dispersement of spin-to-arm projectiles would not result in the release of armed weapons.
SUMMARY OF THE INVENTION
The present invention is an arming mechanism for spinning projectiles. When the spinning projectile is dispensed, the arming mechanism does not respond until there exists simultaneously a predetermined centrifugal force due to the rotation of the projectile and a predetermined force caused by the airflow passing the projectile as it travels through the air.
A driving force is produced within the arming mechanism by the concerted action of a first means responding to the force caused by the airflow and a second means responding to the centrifugal force. When both forces exist simultaneously, the second means engages the first means by way of a gear drive means. The driving force is the result of the relative motion between the responding first means and second means. An arming means is moved from a safety position to an armed position by the driving force. Should either force fail before the arming means reaches the armed position, the arming means returns to the safety position.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a preferred embodiment of the arming mechanism in an unarmed or safety position;
FIG. 2 is a plan view of the preferred embodiment of the arming mechanism in an armed position; and
FIG. 3 is a sectional view of the preferred embodiment taken along the line 3--3 of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 and 3, a housing 1 by which the arming mechanism within a projectile 2 having an axis of rotation 5, is a cylindrical container open at one end and closed at the other by a base plate 3. A vane shaft 4 is rotatably mounted perpendicular to base plate 3 and extends axially from base plate 3 through an opening in projectile 2. Vane shaft 4 is aligned with the axis of rotation 5 of projectile 2. A vane 5 in the shape of a flat rectangular piece of rigid material is attached by one edge along vane shaft 4 external to projectile 2. A rotor pin 7 is inserted into an axial bore 8 in vane shaft 4 such that rotor pin 7 is contained within housing 1. A gear drive 9, which may be made of rubber or other semihard material, has a flat circular shape with a smooth circumference and is placed on rotor pin 7 adjacent the inside surface of base plate 3. Gear drive 9 is fixed to rotate with vane shaft 4.
As viewed in FIG. 1, a triangularly shaped rotor 10 is mounted at one corner to rotor pin 7 such that rotor 10 may rotate about axis of rotation 5 of projectile 2. Rotor 10 is free to rotate with respect to both rotor pin 7 and gear drive 9. Other arming means having a safety position and an armed position could be used in place of rotor 10.
A detonator 11 is carried by rotor 10 and oriented for firing in the direction parallel to axis of rotation 5. Detonator 11 may be a small quantity of explosive which explodes upon impact with a firing pin to ignite a greater quantity of explosive.
A detent rod 12 is mounted on one side of rotor 10 such that detent rod 12 is perpendicular to base plate 3. A detent cap 13 is slideably mounted to the end of detent rod 12 adjacent base plate 3. A detent spring 14 is placed on detent rod 12 and is compressed between rotor 10 and detent cap 13, thereby forcing detent cap 13 against base plate 3.
A channel 15 for containing and controlling the movement of detent cap 13 is cut into the interior surface of base plate 3. Channel 15 is shaped to conform exactly to the arc described by detent cap 13 as rotor 10 rotates about rotor pin 7. Channel 15 restricts the degree of rotation of rotor 10, because the clockwise rotation of rotor 10 as viewed in FIG. 1 terminates at an arming lock hole 16 in base plate 3. Arming lock hole 16 is of sufficient depth and diameter to allow detent cap 13 to fit securely within it. The location of arming lock hole 16 is such that detonator 11 is aligned with a detonator passage 17 when detent cap 13 is seated in arming lock hole 16. Detonator passage 17 is a circular hole in base plate 3 and provides the only way in which detonator 11 can be struck by a firing pin. This position of detonator 11 constitutes the armed position of the mechanism and is illustrated in FIG. 2. As viewed in FIG. 1, channel 15 need only extend to the left of arming lock hole 16 sufficiently to insure that no part of detonator 11 is exposed to detonator passage 17 when rotor 10 is rotated fully counterclockwise. When detent cap 13 is in that position in channel 15, the mechanism is in the unarmed or safety position which is illustrated in FIG. 1.
A rotor return spring 18 is connected between detent rod 12 and a retaining rod 19 which is attached to base plate 3. Retaining rod 19 is located near channel 15 such that rotor return spring 18 is extended by any clockwise movement of rotor 10 from its safety position as viewed in FIG. 1.
A lockweight 20 is a hook-shaped weight pivotally mounted to the interior surface of the base plate 3. Lockweight 20 pivots about an axis parallel to axis of rotation 5 and as shown in the safety position in FIG. 1 catches rotor 10, thereby preventing any clockwise movement of rotor 10. A lockweight spring 21 is compressed between lockweight 20 and housing 1, whereby lockweight spring 21 must be further compressed before lockweight 20 releases rotor 10.
A gear train 22 includes four gears which perform a gear speed reduction due to their alignment. The base of gear train 22 is a lower plate 23 pivotally mounted parallel to base plate 3 by a shaft 24. A spacer 25 is positioned on shaft 24 between baseplate 3 and lower plate 23 allowing lower plate 23 to move freely with respect to base plate 3.
A gear 26 is rotatably mounted on shaft 24. A gear drive 27, which may be made of rubber or other semihard material, has a flat circular shape with a smooth circumference and is rotatably mounted on shaft 24. Gear drive 27 has a diameter smaller than the diameter of gear 26 and is attached to gear 26 so as to function as a pinion for gear 26. A gear 28 having the same dimensions as gear 26 is rotatably mounted on shaft 24 adjacent gear drive 27.
A shaft 29 is mounted on lower plate 23 parallel to shaft 24. A gear 30 having the same dimensions as gear 26 is rotatably mounted on shaft 29 adjacent lower plate 23. A gear drive 31 having the same dimensions as gear drive 27 is rotatably mounted on shaft 29 and attached to gear 30 so as to function as a pinion for gear 30. The location of shaft 29 is such that gear 26 engages gear drive 31. Sufficient friction exists between the semihard surface of gear drive 31 and the teeth of gear 26 to eliminate the need for teeth in the circumference of gear drive 31. Therefore, the engagement of gear drive 31 and gear 26, as with subsequent gears and gear drives, amounts to mere contact and not the meshing of gear teeth. A gear 32 having the same dimensions as gear 26 is rotatably mounted on shaft 29 and engages gear drive 27 on shaft 24. A gear drive 33 having the same dimensions as gear drive 27 is rotatably mounted on shaft 29 and attached to gear 32 so as to function as a pinion for gear 32. Gear drive 33 engages gear 28 on shaft 24. An upper plate 34, identical to lower plate 23, is rigidly attached to lower plate 23 by rods 35, thereby forming a structure which contains the gears and gear drives mounted on shaft 24 and shaft 29. This completes the structure of gear train 22. Variations in the structure of gear train 22 may be made without altering its function which is to perform a gear speed reduction between gear 30 and gear 28.
A counterweight 36 is rigidly attached to gear train 22 such that the center of gravity of the combination of counterweight 36 and gear train 22 may rotate clockwise about shaft 24, as viewed in FIG. 1, as a result of a centrifugal force created by the rotation of projectile 2 about axis of rotation 5. The clockwise rotation of the combination of counterweight 36 and gear train 22 about shaft 24 causes gear 30 to engage or come into contact with gear drive 9. A counterweight spring 37 is compressed between counterweight 36 and housing 1 such that counterweight spring 37 normally holds the combination of counterweight 36 and gear train 22 in its full counterclockwise position whereby gear 30 does not engage gear drive 9. As viewed in FIG. 1, an arming wire 38 is connected between rotor 10 and a point near the circumference of gear 28, whereby any clockwise movement of gear 28 causes a clockwise movement of rotor 10.
It is apparent from the structure of the preferred embodiment of the arming mechanism that rotor 10 will not be moved to the armed position until there exists simultaneously a predetermined force caused by the airflow as projectile 2 travels through the air and a predetermined centrifugal force caused by the rotation of projectile 2 about axis of rotation 5. The centrifugal force causes gear 30 of gear train 22 which is rotating with projectile 2 to engage or come into contact with gear drive 9. Due to the force caused by the airflow, gear drive 9 is not rotating with projectile 2, and the resulting relative motion between gear train 22 and gear drive 9 causes the gears of gear train 22 to rotate about their own axes thereby advancing rotor 10 to the armed position.
OPERATION
The preferred embodiment was built for use in a spherical projectile designed for release from an airplane. The exterior design of the projectile is such that it causes the projectile to spin about axis of rotation 5 when the projectile is falling through the air. The arming mechanism is located within the projectile so that vane shaft 4 is aligned with axis of rotation 5 of the projectile. However, applicant's invention could be employed to arm any spinning projectile if vane shaft 4 is aligned with the axis of rotation of the projectile, and vane 5 is exposed to the airflow about the projectile as it travels through the air.
Operation of the preferred embodiment requires the simultaneous existence of a predetermined centrifugal force caused by the rotation of the projectile about axis of rotation 5 and a predetermined force caused by the airflow about the projectile as it travels through the air. As will be explained herein the mechanism can be designed to operate at various values of either force by adjusting the spring constant of the various springs within the mechanism. When the projectile containing the preferred embodiment of the arming mechanism achieves the spin rate necessary to produce the required centrifugal force, lockweight 20 rotates counterclockwise and the combination of counterweight 36 and gear train 22 rotates clockwise as viewed in FIG. 1. At this stage in the operation of the mechanism only rotor return spring 18 retains rotor 10 in its safety position. Also, as a result of the rotation of counterweight 36 and gear train 22, gear 30 within gear train 22 engages gear drive 9 on rotor pin 7. However, unless relative motion exists between gear 30 and gear drive 9, gear 30 will not rotate about its axis, and gear train 22 will not be activated. The creation of a relative motion is the function of vane 5 which is attached to vane shaft 4 and exposed to the airflow about projectile 2. When the required value of airflow exists about projectile 2, vane 5 is held in a fixed position parallel to the airflow. This is due to the force caused by the airflow acting against the surface of vane 5. Therefore, vane 5, vane shaft 4, rotor pin 7, and gear drive 9 are rotating with respect to the remaining structure of the arming mechanism which is rotating with projectile 2. Due to this relative motion between gear drive 9 and gear 30, gear 30 is rotated about its axis, and because of the structure of gear train 22, gear 26, gear 28, and gear 32 are rotated about their respective axes with a speed reduction occurring between successive gears. Since the circumference of gear 28 is linked to rotor 10 by arming wire 38, the rotation of gear 28 causes the rotation of rotor 10 until rotor 10 reaches the armed position as shown in FIG. 2. Rotor 10 is locked in the armed position by detent cap 13 being forced into arming lock hole 16 by detent spring 14. Detonator 11 is then in a position directly over detonator passage 17 for firing by a firing pin.
It is apparent that the value of the force caused by the airflow necessary to hold vane 5 stationary depends on the spring force of rotor return spring 18, which acts to prevent the rotation of the gears in gear train 22. Using the projectile as a reference, vane 5 and vane shaft 4 rotate with respect to the projectile when vane 5 is held in one position by the airflow. As such, vane shaft 4, by means of gear drive 9, rotates the gears of gear train 22 against the force of rotor return spring 18 which acts to prevent such rotation. If either input, centrifugal force, or the force caused by the airflow, fails before rotor 10 is locked into the armed position, rotor return spring 18 returns rotor 10 to its safety position.
The preferred embodiment described herein is merely one arrangement for applying the principles of the invention. It should be understood that other arrangements or modifications of the mechanism may be apparent to those skilled in the art, and such rearrangements or modifications would not alter the effect or scope of the invention.