US3016827A

US3016827A - Aerodynamic roll control system

Info

Publication number: US3016827A
Application number: US824752A
Authority: US
Inventors: William Hunter A Boyd
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-07-02
Filing date: 1959-07-02
Publication date: 1962-01-16
Anticipated expiration: 1979-01-16

Description

Jan. 16, 1962 w. H. A. BOYD AERODYNAMIC ROLL CONTROL SYSTEM Filed July 2, 1959 INVENTOR WILL/AM HUNTER A. BOYD United S ates. Patent O.

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relatesto an improved and simplified system for preventing roll of a missile or bomb about its longitudinal axis when the missile is falling or flying in an air stream.

Known prior art roll control systems include systems with movable control surfaces which operate to control or prevent roll by servomechanisms which are initiated by some type of sensing component such as a gyroscope. Other systems use .a rotating gyro-wheel which spins when the missile falls through an air stream and stabilizes a movable control surface to which the gyro-wheel is connected. Although these known roll control systems usually operate satisfactorily, they are too expensive and complex to use with small missiles or bombs.

It is an object of this invention, therefore, to provide an automatic roll control system which can be inexpensively and easily constructed from existing bomb and missile fins after a minor amount of modification of the fin structure.

According to this invention, a conventional bomb or missile fin is cut to provide a fin section which remains fixed to the missile body, a flap and a trim tab. The flap and tab so out are hinged to the fin section at approximately right angles to each other and are connected by a simple channel-shaped linkage. The flap is very sensitive to missile roll and is connected to the tab in such a way that the tab will be moved upon movement of the flap so as to produce a corrective aerodynamic force which nullifies the roll of the missile.

The specific nature of the invention, as well as other objects, uses and advantages thereof, will clearly appear from the following description and from the accompanying drawing, in which:

FIG. 1 is a side elevation of a typical bomb or missile fin assembly which has been modified in accordance with this invention.

FIG. 2 is an end elevation of FIG. 1, showing a position which the flap and tab may assume as a result of missile roll.

FIG. 3 is an enlarged view of a channel member which connects the flap to the tab.

As shown in FIG. 1, the missile or bomb 10 has a conventional flat, triangular fin 11 affixed thereto at the tail end. The missile or bomb 10 to which the fin is afi-lxed is of the conventional type having an elongated body with its longitudinal or roll axis X-X in the line of flight of the missile or bomb. Although only one fin is shown it is to be understood that any desired number of fins may be modified so as to provide hereinafter disclosed automatic roll control system. Fin 11 is cut along a line parallel to the roll axis to provide a flat stationary section 12 and a flat triangular flap 13. Hinges 14 mount flap 13 to the outermost edge 12a of section 12 for pivotal movement about an axis which is parallel to the longitudinal or roll axis of missile 10.

Affixed to the trailing edge 15 of section 12 is fiat, substantially rectangular trim tab 16 which is obtained by merely cutting a substantially rectangular section from 3,016,827 Patented Jan. 16,- 1962 ice fin 12. Tab 16 is pivotally mounted to the trailing edge 15 of fin 12 by hinges 17. The axis about which trim tab 16 pivots is substantially perpendicular to the roll axis of the missile 10.

Channel member 18 provides a relatively simple connection between flap 13 and trim tab 16. This element, shown enlarged in FIG. 3, consists of a substantially U-shaped channel section 19. Extending from channel section 19 is a diverging shoulder section 20 and a converging section 21. The ends 22 of section 21 are spacedapart a distance which is slightly wider than the distance between the sides forming U-shaped section 19. Section 19 fits snugly over the surfaces of flap 13 and is secured to the trailing edge 15 of flap 13 by rivets or other suitable connecting means.

Ends 22a and 22b have

opposed edges

22a and 22b respectively, which are spaced apart a distance slightly greater than the thickness of tab 16. Because of the angle a between the shoulder section 20 and section 21, tab 16 will not be bent by

edges

22a or 22b when flap 13 pivots on hinges 14. Angle a is approximately degrees.

As flap 13 pivots on hinges 14, one of the

opposed edges

22a or 22b will contact the opposite sides of tab 16 thereby pivoting that tab on hinges 17. It will be evident that the

particular edges

22a or 22b which contacts and drives tab 16 will depend upon the direction of pivoting of flap 13. Flap 13 pivotsin response to a greater air pressure against one side than the other side of the flap.

For example, as shown in FIG. 2, if flap 13 is pivoted in a direction opposite that of arrow A, as a result of rotation of the missile 10 about its roll axis in the direction of arrow A, edge 22b will be driven against the surface of tab 16. The forceful engagement between edge 22b and the surface of tab 16 will drive the free end of the tab towards the nose of missile 10 and de crease the angle between the tab and the flap 13 from substantially degrees to some angle less than 180 degrees. The direction of pivot of tab 16 is indicated by arrow B in FIG. 2. Movement of tab 16 in the direction of arrow B will provide an inclined surface to the air stream. This inclined surface will produce a torque on fin section 12. which is opposite in direction to that shown by arrow A. As a result, the missile 19 will be automatically stabilized against roll. Should missile 10 roll in a direction opposite in direction to that shown by arrow A, flap 13 and tab 16 will move in an opposite direction to that shown in FIG. 2 and thereby automatically prevent roll in this direction.

Although fiap 13 is shown as triangular in shape, the

particular shape is not critical. The flap will function satisfactorily even though it is some other configuration, such as rectangular, as long as the flap is mounted for rotation about an axis which is substantially parallel to the roll axis of the bomb or missile 10.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction and arrangment within the scope of the invention as defined in the appended claims.

I claim as my invention:

1. A roll control system for a missile having an elongated body with the longitudinal axis in the line of flight of said missile, said system comprising: a fin section mounted on the tail end of said missile perpendicular to the longitudinal axis thereof, a flap pivotally mounted to the end of said fin section, said flap adapted to move in response to an increase in air pressure on one side thereof as a result of missile roll about an axis substantially parallel to said longitudinal axis, a trim tab pivotally mounted to the trailing edge of said fin for pivdtal movement about an axis Substantially perpendicular to said longitudinal axis,- and a channel member, one end of said member being fixed to the trailing edge of said flap and the other end fprming a painqf spaceds a'rt 'dges'adapte d to alternately Contact opposite faces bf saidtfii'n tab depending upon the direetion of move mentor said flap g 7 V V 2. A roll control system as defined in claim 1, wherein one end df 'said' Channel member cbmprises a pair of sp'aeed apart parallel edges adapted to fit over a ortion 10 2,520,665

4 of the trailing edge of said flap, a pair of opposed edges on the other end of said member, said edges being spacedapart a distance slightly greater than the width of said tab so that each edge can alternately contact one face 5 of said trim tab upon movement of said fiap..

References Cited in the file of this patent UNITED STATES PATENTS Williams Feb. '20, izs Warren Aug. 29, 1950 t I l l