US3710715A - Volute spring stabilizer - Google Patents

Abstract

A volute spring stabilizer for controlling the trajectory of an ordnance munition such as a bomb, bomblet or canister, and consists of a flat strip of spring steel wound in a clockspring manner. The wound spring is nested in a cavity formed in the base of the munition, or may be left fully extended. Centrifugal force generated by tumbling or oscillating of the munition will cause the spring to extend to provide a stabilizing tail to enhance the stability of the munition in flight.

Description

United States Patent 91 Hootnagle 11. 3,710,715 [4 1 Jan. 16, 1973 22 Filed:

[ 54] VOILIUTE SPRING STABILIZER [75] Inventor: Wayne E. Hooinagle, Waterloo,

Iowa

[73] Assignee: The United States oi America as represented by the Secretary of the Army Nov. 24, 1970 [21] Appl. No.: 92,488

[52] US Cl. ..102/4, 102/72, 244/327 [51] Int. Cl ..F42b 25/116 [58] Field of Search .l....l02/2, 4, 7.2; 244/326, 3.27

[56] References Cited UNITED STATES PATENTS 3,494,284 2/1970 Gross ..lO2/2 X 2,281,2l3 4/1942 Thaden ..lO2/2 3,282,216 11/1966 Calfee et al. ..lO2/2 FOREIGN PATENTS OR APPLICATIONS 607,239 3/1926 France "344/327 Primary Examiner-Samuel W. Engle Attorney-Edward J. Kelly, Harry M. Saragovitz, Herbert Berl and Daniel D. Sharp [57] ABSTRACT A volute spring stabilizer for controlling the trajectory of an ordnance munition such as a bomb, bomblet or canister, and consists of a flat strip of spring steel wound in a clockspring manner. The wound spring is nested in a cavity formed in the base of the munition, or may be left fully extended. Centrifugal force lgenerated by tumbling or oscillating of the munition will cause the spring to extend to provide a stabilizing tail to enhance the stability of the munition in flight.

5 Claims, 6 Drawing Figures VOLUTE SPRING STABILIZER This invention relates to a volute spring stabilizer and specifically to a device for improving the flight characteristics of a munition such as a bomb, etc.

Bombs or canister type ammunition that are fired from a mortar are subject to tumbling and/or oscillating during flight. This impairs its trajectory with respect to its flight path and eventual target impact surface.

Existing stabilizers for munitions consist principally of ribbons and/or fixed tabs that are attached to the base of the munition and have not been too effective.

The present invention provides a greater flight orientation over existing devices by a volute spring that is nested in compressed condition in a recess formed in the base of the munition. The spring will normally remain in its compressed condition until tumbling or oscillation of the munition caused by centrifugal force occurs in flight, then the spring will extend outward to form an empty hollow elongated inverted frustoconical tail to overcome the aforesaid forces. Its unique configuration permits it to adjust to individual conditions of release. Its extension will increase as release condi tions become more severe and will increase the restoring moment of the falling object. It will retract to its compressed condition in the recess as it approaches terminal velocity and thereby produce consistent orien tation with a short time interval. The volute spring reduces the terminal velocity of the munition by virtue of air resistance and the throttled passage of air between its convolutions. The device may be used with either a projected or free falling munition.

It is therefore a principal object of this invention to provide a stabilizer for controlling the flight trajectory of a munition in flight.

Another object is to provide a stabilizer for correcting the flight path of a munition when tumbling or oscillation of the munition occurs due to centrifugal force generated by the munition in flight.

Another object is to provide a volute spring normally confined in compressed condition within a recess formed in the base of a munition that will extend outward upon tumbling or oscillation of the munition to provide a stabilizing tail.

These and other objects and advantages of the present invention will be fully apparent from the following description when taken in connection with the annexed drawing, in which:

FIG. l is a side elevational view, partly in section of a munition showing the stabilizer as mounted in confined condition in a recess located in the base thereof;

FIG. 2 is a similar view showing the stabilizer in its extended position at its free height;

FIG. 3 is a side elevation of a tapered blank from which the volute spring is made;

FIG. 4 is a partial view of the base ofa munition and showing the tapered spring in confined condition in a modified base;

FIG. 5 is a side elevation of a blank having equal width throughout its length, and;

FIG. 6 is a sectional view ofa modified stabilizer and shown attached directly to the flush base of a free fall type munition.

Referring to the drawing, reference character 1 designates a munition. Its rear base has an outer flange 2 and is provided with an annular recess 3, as shown. The stabilizer of this invention is generally indicated by 4 and in FIG. 1 it is shown as confined in the recess 3. The convolutions of the spring are indicated by 5. Spring 4 is secured at its innermost convolution (apex) to the floor of recess 3 by suitable means such as spot welding as at 6. For purposes of securement, the apex will be formed of a closed coil 7 to give greater rigidity at its base. The outermost convolution of spring 4 engages flange 2 while the spring is confined in recess 3.

In FIG. 3 there is illustrated a flat strip blank 8 which the volute spring is wound and is tapered along its length to a narrow outermost convolution. The wider end of spring 8 will be at its apex. A modified manner of securing the spring 8 to the floor of recess 3 is shown in FIG. 4, In this case, the floor of recess 3 is made to form a post 9 at its center to receive the wide end of spring 8.

A blank 10 is shown in FIG. 5 and consists of a flat strip having equal width throughout its length.

The stabilizer may be mounted in free height condition when used with a free fall type munition wherein the munition is tossed from an aircraft, etc. In this case, a volute spring 11 is attached at its apex by any suitable means centrally to a munition having a flush base 12. When used in conjunction with such flush base munition, the volute spring 11 may also have an overall diameter greater than that of the munition 12 as when such munition is of a very heavy weight (see FIG. 6).

It is apparent from the foregoing that a novel stabilizer has been devised to improve the trajectory of a munition.

lWhat is claimed is:

1. In a munition having a body and a rear base, said rear base having a floor and an outer flange defining a relcess,

lthe improvement comprising, in combination l therewith, a rear stabilizer for controlling the l trajectory of said munition, said rear stabilizer comprising a volute spring, and means for attaching the innermost convolution of said volute spring directly to the center region of said floor of l said recess,

lsaid spring normally being confined in compressed condition in said recess and having its outermost convolution in engagement with the flange of said recess, and said volute spring in the released p0sition forming an empty hollow elongated frustoconical stabilizing surface at the rear of said munition;

whereby when said munition is launched, said spring will extend itself outwardly upon centrifugal forces being generated in flight by tumbling and oscillation of said munition.

2. A stabilizer as set forth in; claim 1 wherein said volute spring comprises a flat strip of steel having equal width throughout its length.

3. A stabilizer as set forth in claim I wherein said volute spring comprises a flat strip which is widest at the innermost convolution of said spring and tapers along its length to a narrow outermost convolution of said spring.

4. A stabilizer as claimed in claim 1 wherein the inner convolution of said volute spring is spot welded to the floor of the base of said munition.

5. A stabilizer as set forth in claim 1 wherein said means for attaching the innermost convolution of said spring to said floor is a post disposed at the center region of said floor.

Claims (5)

1. In a munition having a body and a rear base, said rear base having a floor and an outer flange defining a recess, the improvement comprising, in combination therewith, a rear stabilizer for controlling the trajectory of said munition, said rear stabilizer comprising a volute spring, and means for attaching the innermost convolution of said volute spring directly to the center region of said floor of said recess, said spring normally being confined in compressed condition in said recess and having its outermost convolution in engagement with the flange of said recess, and said volute spring in the released position forming an empty hollow elongated frustoconical stabilizing surface at the rear of said munition; whereby when said munition is launched, said spring will extend itself outwardly upon centrifugal forces being generated in flight by tumbling and oscillation of said munition.

2. A stabilizer as set forth in claim 1 wherein said volute spring comprises a flat strip of steel having equal width throughout its length.

3. A stabilizer as set forth in claim 1 wherein said volute spring comprises a flat strip which is widest at the innermost convolution of said spring and tapers along its length to a narrow outermost convolution of said spring.

4. A stabilizer as claimed in claim 1 wherein the inner convolution of said volute spring is spot welded to the floor of the base of said munition.

5. A stabilizer as set forth in claim 1 wherein said means for attaching the innermost convolution of said spring to said floor is a post disposed at the center region of said floor.

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