US3566852A

US3566852A - Spring-type end-weighted rope reel chaff dispenser

Info

Publication number: US3566852A
Application number: US766692A
Authority: US
Inventors: Ramon I Padron
Original assignee: US Air Force
Current assignee: US Air Force
Priority date: 1968-10-11
Filing date: 1968-10-11
Publication date: 1971-03-02
Anticipated expiration: 1988-03-02

Abstract

Reellike compartments stacked on a common axis. A steel spring is seated in archimedian spiral groove in the discs of each reel and forms a ramp along which a series of subassemblies is installed. The bias of the spring is to rewind itself about the central axis of the reel causing shortening of the ramp and capsule ejection, with successive decreases in velocities from maximum to zero. Each subassembly comprises telescoping elements held compressed between the discs. Each contains a length of rope. Time delayed means spins each hub individually. The ramps of successive compartments intersect the periphery of the device with angular separations so that capsules can be ejected simultaneously from each compartment with equal velocities but with vector or angular separations, equal to 360* divided by the number of compartments in the stack; this prevents entanglement.

Description

United States Patent I [72] Inventor Ramon I. Padron 2,684,062 7/1954 Rose 124/6 Levittown, Pa.

Primary ExammerGeorge J. Marlo 2:??? Assistant Examiner-William R. Browne [45] Patented Manz, 971 Attorneys Harry A. Herbert, Jr. and Ruth G. Codier [73] Assignee the United States of America as represented by the secretary oflhe Force ABSTRACT: Reellike compartments stacked on a common axis. A steel spring is seated in archimedian spiral grooves in I 4 SPRINGJ'YPE ENWWEIGHTED ROPE REEL the discs of each reel and forms ramp along which a series Of CHAFF DISPENSER subassembhes IS installed. The bias of the spring is to rewind 7 Chin's, Drawing 138$ itself about the central axis of the reel causing shortening of r the ramp and capsule e ection, with successive decreases in [52] US. Cl. 124/6, velocities from maximum to zero Each subassembly 221/92' 124/7 prises telescoping elements held compressed between the [51] Int-Cl. t F4lb 15/00 discs Each contains a length of rope Time delayed means [50] Fleld ofSearch l24/6, 4, 8, spins each hub individually. The ramps of Successive compan 9, 7; 273/101, 95, 106; 221/91 (Inqull'ed ments intersect the periphery of the device with angular separations so that capsules can be ejected simultaneously [56] References Cmd from each compartment with equal velocities but with vector UNITED STATES PATENTS or angular separations, equal to 360 divided by the number of 1,420,660 6/1922 Lombard 124/6 compartments in the stack; this prevents entanglement.

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SPRING-TYPE END-WEIGI-ITED ROPE REEL CHAFF DISPENSER BACKGROUND OF THE INVENTION The invention relates to chaff dispensers, and more particularly to airborne devices for ejecting substances to effect radar interference, and belongs to a general family of mechanisms important in the area of reentry systems penetration aids.

SUMMARY OF THE INVENTION Controlled dispensing of large lengths of End Weighted ropes within one plane generally normal to the principal axis of a system and with such velocity distributions and quantities that the relation between the velocity (V,,) of the initially ejected ropes (Q,,) and the velocity (V and quantity (Q,,) of ropes on any subsequent radially expanding layer is directly proportional:

The object of the invention is the provision of a device for the controlled dispensing at predetermined velocities and in sequential noninterfering orientations of large lengths of end weighted ropes. This is a generic term used herein to cover lengths of materials fabricated into wires or threads, capable of being deployed to full length after being folded and stored inside small cylindrical capsule subassemblies, and without taking a permanent setting.

It is a further object of the invention to eject the capsule subassemblies within the principal plane of each disc or compartment in all directions and with such velocity distributions that the first capsules are ejected at a maximum desired velocity and those subsequently ejected a diminishing velocities approaching zero as the last capsules in the compartment are ejected. Thus, there will be uniform population density within the radially expanding circular cloud of ejected, rope dispensing, discs in the two dimensionalprincipal plane.

The capsules traveling along the Archimedian spiral ramp are subject to the frictional force of the spiral spring. The capsule subassembly will not move along the ramp and in the general direction of rotation until the frictional force is smaller than the component of centrifugal force in the opposite direction.

A further object of the invention is the production of a chaff dispensing device which is compatible with other systems and can be produced and distributed as a unit adaptable to a general family of mechanisms in the areas of reentry systems penetration aids.

It is a further object of the invention to provide a unique design for a system effecting the general objects as outlined above.

The device operates in two stages. The first stage is the dispensing of the reellike compartments which are stacked individually and separately on a common axis. All of the reels are set spinning simultaneously by timed devices, the choice of which is optional. These devices are standard and though es sential to the operation, they form no part of the-present invention as claimed.

The design of the reels, however, and the design of the capsule subassemblies which form the second stage, are the essentials of the invention.

DESCRIPTION OF THE DRAWING FIG. 1 is a schematic view of a stack of reels;

FIG. 2 is a schematic end view of a single reel with the end discs removed; and

FIG. 3 is a view of a capsule subassembly undergoing separation.

FIG. 4 is a view of capsule subassemblies being discharged from the rotating ramp strip spring.

DESCRIPTION OF THE PREFERRED EMBODIMENT A series of reel compartments 10 are stacked in an axial stack 12, which, in the vocabulary of the art, is called a canister. Each reel includes a pair of discs 14 and a hollow hub 18. The discs 14 are separated in their internal dimension by the compressed length of the cylindrical capsule subassembiies 16 (See FIG. 2). Each subassembly comprises a pair of

telescoped sections

28 and 30 positioned so that the axis of each capsule cylinder is parallel to the reel stack axis and perpendicular to the end plates 14. As before stated, each reel compartment is equipped with any one of a family of standard design spin producing timed mechanisms (not shown), to spin the discs 14. These safing and arming mechanisms include classic delay timer arrangements, usually pyrotechnic, and are not part of this invention. Their function is the controlled simultaneous spinning release of all reel compartments 10. The device described herein is considered for exemplary purposes to be set spinning in a clockwise direction. The invention need not be so limited. The space within the hub 18 also serves to accommodate a rod (not shown) useful in storing and moving the stacked reel series. This rod is not a part of the present invention.

Each disc 14 is provided along its inner face with a groove 20 machined along an increasing radial distance from the axis of the reel stack 12. The grooves 20 follow the classic Archimedian spiral function r 6 tan a or generally r a 9 where r is the radius, a is the constant slope and 6 is a rotational angular position along the planes of the reels.

In the basic design a is selected numerically smaller than the friction coefficient, determined empirically for the combination of materials used between the cylindrical capsule subassemblies and the material of the ramp.

A negator strip spring 22 is seated in grooves 20, exerting a constant biasing force to rewind itself around the hub 18. It is the function of this strip spring 22 to provide the sequential release of the capsules 16. It does this by instantaneously removing the ramp and therefore removing the holding friction force, when the individual capsule reaches the end of the ramp at the periphery and is subject only to centrifugal force. A narrower strip 24 of suitable material is trapped between the ramp strip spring 22 and the capsule subassemblies l6 and exerts a friction force against movement of the capsules. This narrow strip of suitable material is attached at its inner end to the hub 17 and has by means of a lug its outermost end a slug 26 of a suitable dense material.

As the ramp is removed by the rewind retraction of the strip spring 22 the centrifugal force exerted on the slug 26 and the mass of the strip 24 is in a direction radially away from the hub 18. The effect of the increase of the radial distance between the center of gravity of the retained strip/slug 26 mass combination is to increase the moment of inertia of the remaining disc capsules, thereby decreasing the rate of spin to permit the controlled change in ejection (tangential) velocity (r,w,) of the subsequent capsule, since r cannot be changed to zero due to the real presence of the hub 18.

For an understanding of the operation of this mechanism, it is necessary to consider the machine, as noted above, as a twostage deployment device. The first stage is the disc dispenser which ejects the second stage, the capsule subassembly, which in turn separates or explodes by virtue of the stored energy of the spring, to ejectthe rope.

With respect to the operation of the first stage, the disc dispenser, it is apparent that with no external disturbances .occurring, the capsule subassembly will not move along the ramp in the general direction of rotation until the friction force is smaller than the component of the centrifugal force in the same direction as when alpha is greater than D (the friction angle, e. g. the friction coefficient in small angles). When alpha is smaller than 1 the capsule will continue to move circumferentially at a distance r from the center and with a tangential velocity of r w It also follows that the instantaneous removal of the ramp will result in the release of thecapsule with said velocity r w and in the general direction normal to the instantaneous angular location 1 of the capsule. With regard to the conservation of angular momentum, and since each element of the system contributes to the overall angular moment of the disc system individually, it also follows, that if each capsule is ejected from its original position and no resulting change of moment arm about the principal axis occurs of the other capsules, then the angular velocity of the disc system will not change appreciably other'than by the effect of the reverse torque x time impulse created by the friction force of the capsule being ejected against the inner face of the reel baffies and which can be predicted to be very small considering the predictably low force of the springs built into said capsules.

On the other hand, since it is predictably desirable that ejection velocity gradient from the first capsule ejection to the last capsule ejection be made to vary from V,,,,,, to V equal to or near zero, which will be for the capsules nearest to the hub of the reel stack, the design is intended to consider both the decelerating (angular) effect of above stated friction torque impulses per ejection and the accelerating effect created by the spiral ramp retraction (r decreasing) and include in the design and for the purpose of applying a positive despin controlled mechanism a despin tape played out mass or masses (depending on the number of ramps) which will play out, extending the radial distance of a slug or mass of suitably dense material by the coordinated controlled retraction of the ramp strip.

Since it is both desirable and necessary to the efficient utilization of the machine to be able to deploy the capsules and without tangling the ropes into a constant density circular expanding two dimensional cloud, two conditions are required to be met:

a. The number of capsules being ejected between the first ejection and the last must vary linearly and between the maximum number predictably desirable by any specification and a number approaching zero for the last ejection.

b. The ratio between the number of capsules being ejected within any time increment and those being ejected within another, but equal time increment corresponds proportionally to the ratio of the average velocities of the capsules being ejected during those time intervals or The capsule subassembly 16, as illustrated in FIG. 3, consists of two cylindrical cup-

shaped telescoping halves

28 and 30, each provided with a circular end plate 32 and 34, respectively. These plates extend beyond the circumferences of the

cylindrical portions

28 and 30, and provide seats for a compression spring 36. In the assembled position, inside the reel 12, one-half of the capsule fits over the other, providing a closed assembly, within which is stored the rope payload 38. Ends of the rope are secured to the capsular halves by any expedient method suitable for the particular type of the materials of the rope as, for example, welding, soldering, knotting, gluing, bonding, etc. The ropes are released to their full length by the release of a stored spring impulse which impart to the

halves

18 and 20 of the capsule subassembly a velocity increment. The magnitude of the velocity increment is such that there is sufficient separation between the ejected ropes to prevent their entanglement.

Alternate configurations of the mechanisms above described can be used without departing from the invention as claimed.

Although the invention has been described with reference to particular embodiments, it will be understood to those skilled in the art that the invention is capable of a variety of alternative embodiments within the spirit and scope of the appended claims.

Iclaim:

1. In a chaff dispenser capable of acquiring spinning motion,

said dispenser comprising a reel compartment, said reel compartment being rotatable about its central axis, said creel compartment having a central hub and a pair of discs supporting therebetween an Archimedian ramp, said reel compartment extending from a position adjacent said hub to the periphery of said discs, a series of subassembly capsules containing chaff, said capsules arranged in single file and located along said Archimedian ramp from a position adjacent the hub to a position adjacent the end of the ramp, so that said capsules may travel along said ramp by centrifugal force and be dispensed individually at the outer end of said ramp.

2. A chaff dispenser as claimed in claim 1, wherein the reel compartment is adapted to be positioned adjacent other reel compartments on a common axis, and the position of said reels with respect to each other is such that the intersections of said ramps with the peripheries of said reels bears a relation of 360/N where N is the number of reels in the series, so that subassemblies containing chaff are dispensed in all directions about said axis.

3. In a chaff dispenser as claimed in claim 2, means for controlling the velocity of travel of said subassemblies along said ramp, said means comprising, a weighted member on the ramp that exerts a frictional force on said subassemblies and in a direction counter to centrifugal force.

4. A chaff dispenser as claimed in claim 3, wherein said ramp retracts toward the hub during the rotation of a reel compartment, the centrifugal force on said subassemblies increases during reel compartment rotation as the subassemblies travel along said Archimedian ramp in the direction of said periphery of the discs, resulting in a decrease in the velocity of the successive subassemblies as each subassembly leaves said ramp during the time the ramp is being retracted.

5. A chaff dispenser as claimed in claim 4, wherein the means for exerting frictional force on said subassemblies comprises a narrow weighted strip engaging the ramp and positioned between the subassemblies and the ramp.

6. A chaff dispenser as claimed in claim 1, wherein each subassembly capsule comprises a pair of telescoping caps arranged with their axes parallel to the central axis of said reel compartment, said telescoping caps being spring biased to separate and release the chaff contained therein, and wherein the bias of said spring is restrained between inwardly facing surfaces of said discs.

7. A chaff dispenser as claimed in claim 1, wherein said chaff comprises ropes dispensable at controlled reel compartment velocities for controlled distribution, and wherein said ropes are end weighted by end segments of said capsules.

Claims

1. In a chaff dispenser capable of acquiring spinning motion, said dispenser comprising a reel compartment, said reel compartment being rotatable about its central axis, said creel compartment having a central hub and a pair of discs supporting therebetween an Archimedian ramp, said reel compartment extending from a position adjacent said hub to the periphery of said discs, a series of subassembly capsules containing chaff, said capsules arranged in single file and located along said Archimedian ramp from a position adjacent the hub to a position adjacent the end of the ramp, so that said capsules may travel along said ramp by centrifugal force and be dispensed individually at the outer end of said ramp.

2. A chaff dispenser as claimed in claim 1, wherein the reel compartment is adapted to be positioned adjacent other reel compartments on a common axis, and the position of said reels with respect to each other is such that the intersections of said ramps with the peripheries of said reels bears a relation of 360*/N where N is the number of reels in the series, so that subassemblies containing chaff are dispensed in all directions about said axis.