US3181466A - Spin compensating switch for a projectile fuze - Google Patents

Description

May 4, 1965 N. czAJKowsKl 3,181,466

SPIN COMPENSATING SWITCH FOR A PROJECTILE FUZE Filed Feb. 4, 1957 2 Sheets-Sheet 1 FIGJ. FIG.2.

l lrllllllll INVENToR N. CZAJKOWSKI 'BY/ wm 7K.

A TYS SPIN COMPENSATING SWITCH FOR A PROJECTILE FUZE Filed Feb. 4, 1957 May 4, 1965 N. czAJKowsKl 2 Sheets-Sheet 2 DEFLECTION INVENTOR. N. CZAJKOWSKI 9 M W0' ATTYS United States` Patent Ov 3,181,466 SPIN CGWENSATN G SWITCH FOR A PRJECTILE FUZE Norman Czajkowslii, Chevy Chase, Md., assigner to the United States of America as represented by the Seere- Filed Feb. 4, 1957, Ser. No. 638,184

6 Claims. (Cl. 102-70.2)

(Granted under Title 3S, 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 for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to a centrifugally operated switch for use with a projectile fuze and more particularly to a centrifugally operated switch which is actuated to a closed position when the rate of spin of the projectile during flight has decreased suiiiciently from the value of the initial rate of spin imparted thereto as the projectile is tired from a gun regardless of the maximum value of the initial rate of spin.

The purpose of this invention is to provide a new and improved switch for an anti-aircraft projectile or spin stabilized rocket, as the case may be, moveable to a closed position at a predetermined distance from the gun controlled by the angle of elevation of the gun at the instant ofdiring and which is independent of the initial rate of spin imparted to the projectile by the gun.- As is well known, the difference in rate of spin of projectiles tired from new guns and from old `or worn guns respectively varies considerably, the spin in the case of a projectile fired from an old gun being considerably less than the rate of spin of the projectile when tired from a new gun.

In devices of this character heretofore devised it has been the usual practice to employ a reed type switch having a reed Contact element actuatable to a moved or open position in response to the centrifugal force initially applied thereto as the projectile is red frorn'the gun. When the rate of spin has decreased to a predetermined value during the tiight of the projectile alonga trajectory the centrifugal force acting on the movable Contact element is reduced to a value suicient to cause the switch to close. This type of switch is usually employed with a projectile fuzed in such a manner that the fuze is actuated as the switch closes to eiiect self-destruction of the projectile whereby live anti-aircraft projectiles or spin stabilized rockets are prevented from falling upon friendly troops or material. When employed with a projectile tired from an old worn gun, such a switch possesses the disadvantage that the projectile may be self-destroyed before it reaches a target by reason of the low initial spin rate imparted thereto by the gun. Conversely, if the switch is adjusted initially to be employed in a projectile tired from an old worn gun, such a projectile may fail to he self-destructive when iired from a new gun having a higher spin rate whereby the live missile may fall upon friendly troops or material.

The device of the present invention possesses all of the advantages of the foregoing devices of this general type and none of the foregoing disadvantages. This desirable result is achieved by automatically compensating for variations in the spin rate of the projectile initially imparted thereto by a gun. The switch thus operates when the differential rate of spin between the initial rate and the rate of spin at which the firing or switch contact is closed has reached a value corresponding to a certain predetermined tractional portion of the trajectory of the projec- Patented May 4, 1955 tile. The manner in which this is achieved will be more clearly apparent as the description proceeds. t

One of the objects is to provide a centrifugally actuated switch for a spin projectile in which new and improved means are employed for closing the switch by a decrease in the rate of spin of the projectile in predetermined time delayed relation with respect to the tiring of the projectile from a gun and which is substantially independent of the initial spin rate imparted thereto by the gun.

Another object is to provide a centrifugally actuated switch for a projectile fuze in which one of the switch closing elements is settable to a final switch closing position selectively in accordance with the maximum rate of spin applied to the projectile by a gun from Which the projectile is fired.

Still another object is to provide a centrifugally actuated switch for the fuze of a spin projectile in which one of the switching elements is settable from an initial closed position to a tiring position selectively in accordance with the rate of spin initially imparted to the projectile as the projectile is ired from a gun.

A further object is to provide a new and improved centrifugally actuated switch for a spin type missile in which new and improved means are employed for locking one of the Contact elements of the switch in a ring position correlative with the maximum spin rate applied to the missile. i

A still further object is to provide a centrifugally operated switch for the fuze of a spin projectile having new and improved means for preventing the initial spin rate imparted to the projectile from adversely aifecting or influencing the proper operation of the switch and its cooperating elements.

Other objects, advantages and improvements will become more clearly apparent from the following description taken in connection with the accompanying drawings on which like numerals of reference are employed to designate like parts throughout the several views and in which: j

FiG. 1 is a view partly in section of a prior art switch of the general type herein disclosed;

FIG. 2 is a view of the centrifugally operated switch of the present invention according to a preferred embodiment thereof on which is shown the contact elements in an initial closed position;

FiG. 3 is a view similar to FIG. 2 with the switching and locking elements in a position corresponding to maximum spin rate;

FIG. 4 is a view similar to FIG. 3 of the locking and contact elements when the spin rate of FIG. 3 has been somewhat reduced;

FIG. 5 is a view on which is shown the switching elements in a tiring position;

FIG. 6 is a circuit diagram suitable for use with the switch of FIG. 2; FIG. V7 is a chart on which is shown graphically the deflection of the datum and contact reeds of the switch when red from an old gun and a new gun, respectively; and

FIG. 8 is a chart on which is shown in graphic form the operational characteristics of the switches of FIGS. l and 2 respectively when employed in a projectile fired at 3 different angles of elevation.

Referring now to the drawings for a more complete understanding of the invention and more particularly to FIG. i thereof there is shown thereon a switch of the alegres type heretofore devised and comprising a housing indicated generally by the numeral and having an insulating portion 11 secured at one end thereof for supporting a resilient reed type contact member 12. The inner end of the contact member normally rests against a shoulder 13 on the adjusting screw 14. In operation, the switch is spun by the projectile within which it is mounted in such manner that the contact member 12 moves away from shoulder 13 by centrifugal force as the shell is fired from the gun and reengages shoulder 13 when the rate oflspin of the projectile has decreased to a predetermined va ue.

A preferred embodiment of the device of the instant invention is shown on FIG. 2 and indicated generally by the numeral 15, the device comprising a housing or casing 16 having end portions 17 and 13 respectively, the end portion 18 preferably being composed of metal and supporting a contact spring member 19 having a Contact 21 aflixed thereto and in normal engagement with a resilient reed type contact 22. The contact reed 22 is insulated from the end portion 18 in any suitable manner and is provided with a terminal 23 for establishing an external electric circuit thereto. A rod 24 is threaded as at 25 into the casing 16 substantially as shown and provided preferably with a slot 26 whereby the rod may be moved to a predetermined adjusted position within the casing by means of a suitable tool. A locking Washer 27 having an aperture therein of slightly greater size than the rod 24 is slideably carried by the rod and normally held against a shoulder 28 by the contact spring member, hereinafter referred to as the datum member 19 substantially as shown. The reed contact element 22 is initially tensioned against the contact 20, this preloading being sufficient to maintain good electrical conductivity between the members 19, 22, and pressure against the locking member 27 is such that the lock mechanism is restrained against movement due to rough handling.

The operation of the switch of FIG. 2 will now be described. Let it be assumed, by way of example, that the switch is mounted within a projectile in such manner that the rod 241 is normal to the axis of spin thereof and that the axis of spin of the projectile is below the bottom portion of the rod 24 as viewed in the drawing. As the projectile is ired from a gun, the centrifugal force imparted thereto by the gun riiling causes the contact spring members 19 and 22 and the locking washer 27 to be moved to a position by centrifugal force such as shown on FIG. 3, the reed type contact member 22 moving through a greater distance than the datum contact member 19 by reason of the fact that the contact members 19 and 21 possess dierent spring constants. As the contact spring 22 is disengaged from contact 21 the terminal 23 thereof is disconnected from ground.

As the rate of spin decreases during the flight of the projectile contact springs 19 and 22 move towards their initial positions by reason of the preloading tension of the springs. When this occurs the locking member 27 is tilted, as shown in FIG. 4, into locking engagement with the rod 24 and further inward movement of the datum spring 19 is thus prevented. As the spin rate decreases further, however, the reed type contact spring 22 continues to move toward the initial position until the rate of spin has decreased to a value such as to cause the contact element 22 to engage contact 21, FIG. 5. When this occurs ground is again applied to terminal 23 of contact element 22.

From the foregoing it will be understood that the locking member 27 is moved to a locking position along the rod 24 correlative with the maximum rate of spin of the projectile at the instant of leaving the muzzle of the gun. The datum spring 19 is thus locked in a final position correlative with the maximum spin rate of the missile and the delay in closing the switch contacts thereafter is thus correlativo with the distance which the missile has traveled from the gun, the distance being related to the time of travel of the missile during flight required for the reed type contact 22 to move from the position Shown in FIG. 3 to the closing or tiring position of FIG. 5.

Obviously if the projectile is iired from a new gun the position of the contact member 19 and locking member 27 will be moved further from the initial position thereof as the projectile leaves the muzzle of the gun by reason of the high spin rate and, conversely, if the missile was fired from an old worn gun these elements would be moved a lesser distance from the initial position thereof by reason of the decreased rate of spin. In the rst case assumed, the locking member would be locked further along the rod 24 and thus the closing or tiring position of the switch would be moved further from the initial position thereof and the switch would be closed at a higher rate of spin than would be the case if the missile was tired from an old worn gun.

This condition will be more readily understood by reference to FIG. 7 on which is shown two curves 29 and 31 representing deflections of the contact and datum reeds respectively over a spin range of 0 to 675 revolutions per second. If it be assumed that the maximum spin of the projectile fired from an old gun is 5 32 revolutions per second, the datum reed will be moved and locked at point 32 of curve 31 and the contact reed will be moved to the point 33 of curve 29. The switch contacts are now open. Since the rate of spin of the projectile has decreased to 392 revolutions per second, the contact reed will be in a position indicated by the numeral 34 and engage the contact 21 of the datum reed.

When, however, the missile is red from a new gun having a maximum rate of spin of 630 r.p.s. applied thereto by the gun the datum and contact reeds will be moved to the points 35 and 36 respectively, the datum reed being locked at this position by the locking washer 27. When the rate of spin has decreased to 462 r.p.s. the contact reed will be moved to position 37 and engage contact 21 of the datum reed.

The correlation between this operation of the switch and the range at which the switch operates to close its contacts is shown on FIG. S in graphic form for three different angles of elevation of the gun. There is also shown on this figure ranges corresponding to the prior art switch of FIG. 1 and -a comparison of the timed operation of these switches when the projectile in which the switches are carried is red from an old gun and a new gun respectively. The curve 38 is employed to indicate both the maximum altitude and range of a projectile tired from the gun at 10 degree elevation. Considering now the case where the projectile is tired from an old gun and the projectile is provided with the switch of FIG. l, the operation of the switch is indicated generally by the dark portion 39 of the curve and when red by a new gun by the light portion 41 of this curve. There is also shown by the darkened portion 42 of curve 38 the operation of the switch of FIG. 2 when employed with an old gun and by the darkened portion 43 the operation of the switch of FG. 2 when employed with a new gun. It will thus be clearly apparent from an inspection of the figure that the second closure of the switch of the instant invention occurs at substantially the same point on the trajectory regardless of the initial rate of spin imparted to the projectile by the gun in contradistinctiou to the wide variation in range at which the switch of FIG. l operates when employed with old and with new guns.

Curves 44 and 45 are generally similar to curve 38, these curves illustrating the performance of the centrifugal switches of the instant invention and the prior art when fired from a gun of 40 degrees and 70 degrees elevation respectively. The operation of applicants switch when employed with an old gun at an elevation of 40 degrees is shown at i6 and when employed with a new gun at 47. When the angle of the gun is elevated to 70 degrees the operation of applicants switch with an old gun is shown at 48 and when used with a new gun at 49.

The switch of the present invention is well adapted for use in self-destruction of a missile in flight. When so employed it may be connected in any suitable mannerV to achieve this result, a circuit suitable for this purpose being shown on FIG. 6 to which attention is now directed.

A thyratron tube 51 has the control element thereof operatively connected to the output of the amplifier of a proximity fuze, for example, the plate thereof being connected to a firing condenser Cand terminal 23 of applicants switch. The plate is also connected by Way of 'high resistance R to the positive terminal of battery B. The opposite terminal of condenser C is connected to the primer P and thence to ground, the primer P being shunted by a shorting Wire or switching element 52. The filament of the tube is energized by battery A. Batteries A and B, as is well known, are the type adapted to be activated in response to setback force as the missile is fired from the gun. Ground is applied to the various components of the circuit as shown.

As the projectile is fired from the gun and reed type contact 22. is disengaged from contact 21, the shunt circuit is removed from the charging condenser C and the primer P. The energization of battery B causes a charging cur-V rent to flow through R sufficient to charge condenser C to a firing potential, the primer P being prevented from operating rby the switch 52 connected thereacross. When sufficient time has elapsed for condenser C to become fully charged, the switch 52 is opened by a fuze safety device [not shown] which may be of any well known type and the fuze is armed and ready for operation by tube 51 or the centrifugally operated switch, as the case may be. If the projectile moves to a position sufficiently close to the target tube 51 is operated thereby causing the primer to be fired by discharging current from condenser C and explode the missile. If, on the other hand, the missile does not come within lethal range of target before the centrifugal force has decreased to a value sufficient to cause contact spring Z2 to move into engagement withV contact 21, the operation of the centrifugal switch causes the primer to be tired by discharge current from condenser C.

Bniey stated in summary the present invention provides a centrifugally operated switch for use with a spin type missile having means for compensating for variations in the initial spin rate imparted to the missile by the gun in such manner that the switch contacts are closed when the rate of spin of the projectile has decreased to a value controlled by a locking device set to an initial locking position corresponding to the maximum rate of rotation of the missile.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A spin compensating centrifugal switch for use with a spin type project-ile comprising a casing, a lock shaft disposed within said casing and having a shoulder thereon, a circular locking member slideably carried by said shaft and having an aperture therein of slightly greater diameter than the shaft within which the shaft is disposed, a datum reed secured to one end of the casing at an end portion thereof in such manner that the other end of the reed yieldably urges said locking member into engagement with said shoulder, a contact reed of greater flexibility than the datum reed carried by said end portion of the casing and normally engaging said datum reed and a terminal on said contact reed for establishing an external electrical connection thereto.

2. A centrifugally operated switch of the character disclosed for use with a spin type projectile comprising a casing, a locking shaft disposed transversely within said casing and normal to the axis of spin of the projectile, a datum reed carried by said casing and having an end portion in closely spaced relation to said shaft, stop means on said shaft, a locking Washer having an aperture therein of slightly greater diameter than the shaft within which the shaft is disposed, said washer being arranged between the end of said datum reed and said stop means and normally urged against the stop means by the datum reed, a contact on an end portion of said datum reed, a flexible contact reed carried by said casing and insulated therefrom in such manner that the contact reed normally is in predetermined preloaded engagement with said datum reed contact, said contact and datum reeds having different spring constants such that the contact reed is moved ou-t of engagement with the datum reed contact in response to centrifugal force when the projectile is red from a gun, the axis o-f said shaft being normal to the spinV axis of the projectile whereby the locking washer is moved along said shaft and locked thereto in a cocked position by said datum reed as the projectile spin decreases from a maximum value and the contact reed moves into engagement with the locked datum reed in response to a further decrease in the rate of spin.

3. A centrifugally operated switch for use with a spin projectile comprising a pair of normally closed contact elements carried by a Contact reed and a datum reed respectively, each yof said reeds being constructed and arranged to be moved from an initial closed contact position to a moved position by centrifugal force acting thereon as the projectile is fired from a gun, means controlled by the rate of spin of the projectile for locking said datum reed in a firing position correlativo with the maximum rate of said spin, said contact and datum reeds having different spring constants whereby the contact element of the contact reed is disengaged from the contact element of the datum reed in response to the initial spin of the projectile as the projectile is red from a gun and .the contact of the contact reed is moved into circuit closing position with respect to the contact of the locked datum reed as the spin rate of the projectile is decreased by a predetermined amount from the maximum rate of spin.

4. A switch according to claim 3 in which means threadedly engaging said switch is provided for adjusting at will the initial position of said datum and contact reeds.

5. A switch according to claim 3 in which said locking means comprises a locking shaft having a slideable locking member thereon adapted to be moved from an initial position of rest to a final position correlativa with the maximum rate of spin of the projectile in response to centrifugal force and to be cocked in said nal position in locking engagement with said shaft by the datum reed as the spin rate is decreased from said maximum rate.

6. In a spin missile adapted to be red from a gun, the combination of a casing, a ythreaded locking shaft disposed within said casing and having a shoulder thereon, an annular locking disc encircling and slideably carried by said shaft and adapted to be locked thereto selectively in different positions when moved into cocked engagement therewith, a datum reed carried by said casing and having one end thereof yieldably urging said locking disc against said shoulder, a Contact on said datum reed near the free end thereof, a contact reed carried by said casing and insulated therefrom, said contact reed being preloaded into initial engagement with the contact on said datum reed and having a terminal for establishing an external electrical connection thereto, said contact and datum reeds having different spring constants such that Ithe contact reed is disengaged from said datum reed contact and both reeds are tiexed in a direction away from said shoulder by centrifugal force as the missile is tired from a gun, said contact reed deflecting a greater amount than the datum reed and the locking disc following the datum reed alo-ng said shaft whereby the datum reed is locked at the limit of exure thereof by said locking disc as the 7 8 centrifugal force decreases and the disc is moved into References Cited by the Examiner cocked engagement with said shaft, a ring circuit for UNITED STATES PATENTS said missile and means operatively connecting said firing F circuit to said terminal whereby the firing circuit is closed lm-a-n When the rate of spin of the missile has decreased to a 5 value corresponding to the rate required to move the contact on the contact reed to a firing position in engage- SAMUEL FEINBERG P" mary Examiner' ment with the Contact on said datum reed. SAMUEL BOYD, Examiner.

Claims (1)

1. 3. A CENTRIFUGALLY OPERATED SWITCH FOR USE WITH A SPIN PROJECTILE COMPRISING A PAIR OF NORMALLY CLOSED CONTACT ELEMENTS CARRIED BY A CONTACT REED AND A DATUM REED RESPECTIVELY, EACH OF SAID REEDS BEING CONSTRUCTED AND ARRANGED TO BE MOVED FROM AN INITIAL CLOSED CONTACT POSITION TO A MOVED POSITION BY CENTRIFUGAL FORCE ACTING THEREON AS THE PROJECTILE IS FIRED FROM A GUN, MEANS CONTROLLED BY THE RATE OF SPIN OF THE PROJECTILE FOR LOCKING SAID DATUM REED IN A FIRING POSITION CORRELATIVE WITH THE MAXIMUM RATE OF SAID SPIN, SAID CONTACT AND DATUM REEDS HAVING DIFFERENT SPRING CONSTANTS WHEREBY TE CONTACT ELEMENT OF THE CONTACT REED IS DISENGAGED FROM THE CONTACT ELEMENT OF THE DATUM REED IN RESPONSE TO THE INITIAL SPIN OF THE PROJECTILE AS THE PROJECTILE IS FIRED FROM A GUN AND THE CONTACT OF THE CONTACT REED IS MOVED INTO CIRCUIT CLOSING POSITION WITH RESPECT TO THE CONTACT OF THE LOCKED DATUM REED AS THE SPIN RATE OF THE PROJECTILE IS DECREASED BY A PREDETERMINED AMOUNT FROM THE MAXIMUM RATE OF SPIN.

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