GB2369177A

GB2369177A - Aerofoil deployment system

Info

Publication number: GB2369177A
Application number: GB8912631A
Authority: GB
Inventors: William Nash
Original assignee: British Aerospace PLC; BAE Systems PLC
Current assignee: BAE Systems PLC
Priority date: 1989-06-02
Filing date: 1989-06-02
Publication date: 2002-05-22
Also published as: FR2874251A1; GB8912631D0

Abstract

A deployment system for an aerofoil, eg, a tail plane, of a projectile such as a stand-off weapon, includes an actuator 6 that acts upon an aerofoil 4 through only a single interconnecting cable 7 to cause the aerofoil to pivot between stowed and deployed positions about a pivot axis (9).

Description

AEROFOIL DEPLOYMENT SYSTEM This invention relates to an aerofoil deployment system, and in particular to such a system for use with an air-launched stand-off weapon, or similar such projectile.

Such a weapon is a missile or the like that is launched from an aircraft at a distance from the intended target. The missile then flies independently to the target where it delivers a load of submunitions. For the purpose of the flight to the target the missile requires aerofoils such as wings and a tail plane. However, these aerofoils are disadvantageous when the weapon is carried by the aircraft, for reasons of space (for example when the weapon is carried in a weapons bay), and because of the danger that the weapon aerofoils may interfere with the aerodynamic characteristics and behaviour of the aircraft if the weapons are carried on a rack below the aircraft.

Accordingly it is known for the wings and tail plane to be stored in non-operational positions and only moved into operational'in-flight'position after the weapon is launched. This requires an aerofoil deployment system that is reliable but which, in view of the fact that it may only be used once, is relatively simple and inexpensive.

According to the invention there is provided a deployment system for an aerofoil that is pivotable about an axis from a stowed position to a deployed position comprising, an actuator that acts upon a cable fixed at one end to a point on the aerofoil displaced from the pivot axis to cause the aerofoil to pivot about said axis between said stowed and deployed positions.

The actuator may be hydraulic or electromagnetic, but to provide a high force combined with a simple lightweight structure it is preferred that the actuator be of the compressed gas type, or of a gas-generating type.

A single actuator may act upon both cables of a pair of wings, or alternatively a pair of wings may have a common operating cable, so that only one actuator is required for a projectile having a pair of opposed wings. However, it may be preferred to provide an actuator for each aerofoil since this would permit the deployment mechanism to be located within the aerofoil itself. This would be particularly advantageous where the aerofoil is a tail plane adjustably mounted to the fuselage through a spigot.

In such a case the pivot axis may lie in the plane of the aerofoil, and the aerofoil may comprise two parts, a first fixed part and a second part pivotable with respect to the first.

In preferred embodiments, a locking mechanism may be provided to lock the aerofoil in place once it has been deployed, preferably extending for the length of the pivot axis.

Some embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a plan sectional view of a tail plane assembly, Figure 2 is a section along the tail plane pivot, Figure 3 is a view along B-B of Figure 2 and Figures 4 and 5 are alternative views along A-A of Figure 2.

Figures 1 to 5 show how the invention may be applied to an aerofoil such as a tail plane. Figure 1 shows schematically a tail plane 1 that is secured to the fuselage by a spigot 2. It will be appreciated that although only one tail plane 1 is shown and described, two such tail planes will of course be provided, one on each side of the fuselage.

Each tail plane comprises two parts; a first inner part 3 to be fixed to the fuselage, and a second outer part 4 connected to the first at a hinged connection 5. In the stowed condition, not shown, the outer part 4 is folded over the inner part 3 and over the fuselage, or possibly received in a recess formed in the top of the fuselage. In use the tail plane is deployed from the stowed position by causing it to pivot about the hinge 5, in a manner to be described below, until the in-flight position shown in Figure 1 is obtained. Figure 2 shows a section though the tail plane along the line of the hinge.

Pivotal movement of the outer part 4 of the tail plane about the hinge 5 is effected by means of an actuator 6 which may be a compressed gas or gas-generating type actuator. The actuator 6 acts upon a cable 7 that is fixed at one end to the inner tail plane part 3, and at its other end to the outer tail plane part 4, the cable being guided there between by a tensioning pulley 8. As is shown in Figure 3, the cable 7 is fixed to the outer tail plane part 4 at the side of that part opposite from the pivot axis 9 of the hinge in order to provide the necessary turning movement. For smooth operation the cable 7 is guided by guides 10,11 provided in the inner tail plane part 3, and an arcuate guide 12 extending from the outer tail plane part 4. The arcuate guide 12 has its centre of curvature on the pivot axis 9. As will readily be appreciated movement of the cable 7 in the direction of the arrow in Figure 3, which is effected by operation of the actuator 6, causes the outer tail plane part 4 to pivot about the hinge axis 9 (anti-clockwise in Figure 3) until the in-flight position is taken up.

A locking mechanism is provided to lock the tail plane in its in-flight position. Indeed it is advantageous to provide a number of independent locking mechanisms extending along the length of the hinge. In the embodiment shown six such mechanisms 13 are provided, though naturally the number could vary depending on the circumstances.

Figure 4 shows a possible structure for one such locking mechanism 13. A spring-biassed catch 14 is provided fixed to the outer tail plane part 4, and which engages in a recess formed behind the head of a locking member 15 formed on the inner tail plane part 3. As the outer part 4 pivots about axis 9, the surface 16 of the locking member 15 engages the catch 14 and pushes the catch against its spring-biassing until the catch 14 is received within the recess. A spring-biassed locking wedge element 17 helps to maintain this locked configuration by means of a wedging engagement between surfaces 18,19 provided on the catch 14 and wedge element 17 respectively. During the locking action, ie, before the catch 14 engages the recess, the catch 14 forces the wedge element 17 against its spring-biassing until the catch 14 engages the recess, at which point the wedge element 17 springs back to hold the catch 14 locked.

Figure 5 shows an alternative form of locking mechanism 13. The inner tail plane part 3 is provided with a spring catch 20 which may be pivoted about pivot axis 21 against the spring-bias into a recess 22, but which is otherwise outwardly biassed by the spring. The end of the spring catch 20 is provided with a chamfered cam surface 23. As the outer tail plane part 4 pivots into its in-flight position about axis 9, a second cam surface 24, provided at the end of a locking member 25 projecting from the outer tail plane part 4, engages the cam surface 23 to force the catch 20 against its spring-bias into recess 22. With continued pivotal movement of the outer part 4 into its in-flight position the cam surfaces 23,24 no longer engage one another and the head portion of the spring catch 20 engages behind the head portion of the projecting locking member 25 in the manner shown in Figure 5. Subsequently a wedging element 26 may be inserted in the recess 22 to secure the locking mechanism in its locked state.

This tail plane deployment system is particularly advantageous in that the entire deployment system may be contained within the tail plane itself. However, it will be appreciated that it would also be possible to provide a single actuator in the fuselage to deploy both tail planes.

Such a single actuator would act upon either a single cable connecting both tail planes, or separate cables for each tail plane, with in either case the cable (s) extending into the fuselage through the spigots connecting the tail planes to the fuselage.

Claims

CLAIMS 1 A deployment system for an aerofoil that is pivotable about an axis from a stowed position to a deployed position comprising, an actuator that acts upon a cable fixed at one end to a point on the aerofoil displaced from the pivot axis to cause the aerofoil to pivot about said axis between said stowed and deployed positions.
2 A deployment system according to Claim 1 wherein a common cable is fixed between a pair of opposed aerofoils and said actuator acts on a central point thereof, or wherein two cables fixed to respective opposed aerofoils are acted upon by one actuator, whereby only one actuator is required to deploy a pair of aerofoils.
3 A deployment system according to Claim 1 or 2 wherein said pivot axis lies in the plane of said aerofoil when deployed.
4 A deployment system according to Claim 3 wherein said aerofoil comprises a first fixed part, and a second part pivotable with respect to the first, and wherein said actuator is mounted in association with said first part.
5 A deployment system according to any preceding claim wherein a locking mechanism is provided to lock the aerofoil in its deployed position.
6. An aerofoil deployment system substantially as hereinbefore described and with reference to the accompanying drawings.
7. A stand-off weapon having a tail plane unit that is deployed by a system according to any preceding claim.

6 A deployment system according to Claim 5 wherein said locking mechanism extends substantially the length of said pivot axis. 7 A deployment system according to any proceeding claim wherein said actuator is of a compressed gas type.

8 An aerofoil deployment system substantially as hereinbefore described and with reference to the accompanying drawings.

9 A stand-off weapon having a tail plane unit that is deployed by a system according to any preceding claim. Amendments to the claims have been filed as follows 1. A deployment system for an all-moving aerofoil on a missile including an aerofoil having an inner part adjustably mounted to a fuselage of the missile through a spigot and an outer part mounted for pivotal movement between stowed and deployed positions about a pivot axis on the inner part, and an actuator located in said inner part that acts upon a cable fixed at one end to a point on the outer part displaced from the pivot axis to cause the outer part to pivot about said axis between said stowed and deployed positions.

2. A deployment system according to Claim 1 wherein said pivot axis lies in the plane of said aerofoil when deployed.

3. A deployment system according to Claim 1 or 2 wherein a locking mechanism is provided to lock the outer part of the aerofoil in its deployed position.

4. A deployment system according to Claim 3 wherein said locking mechanism extends substantially the length of said pivot axis.

5. A deployment system according to any preceding claim wherein said actuator is of a compressed gas type.