WO1996009955A1

WO1996009955A1 - Linkage to deploy a surface relative to a wing

Info

Publication number: WO1996009955A1
Application number: PCT/NZ1995/000096
Authority: WO
Inventors: Michael Craig Broadbent
Original assignee: West-Walker, Francis, Nigel
Priority date: 1994-09-29
Filing date: 1995-09-27
Publication date: 1996-04-04
Also published as: AU3621695A

Abstract

A leading edge (slat) and/or a trailing edge (flap) lift enhancing surface for an aircraft or a marine craft wing is connected to the wing by a linkage system. This system has at least two parallel spaced apart swing arms (12) with one end of each swing arm being pivoted (15) to the wing and the other end (13) pivoted to the slat or flap. (As depicted the swing arms each consist of one part; however in an alternative arrangement the swing arms are each in two parts hinged in the middle of the arm). A control rod (14) extends between the slat or flap and a base pivot point located on the swing arm (as depicted) or the wing and during deployment rotates the slat or flap about a span line which is substantially parallel to and below the wing.

Description

LINKAGE TO DEPLOY A SURFACE RELATIVE TO A WING

The present invention relates to a mechanical system for deploying leading edge and trailing edge lift enhancing surfaces for aircraft or marine craft wings.

Technical Field

Aerodynamics is but one discipline in the field of fluid dynamics and all technology for aerodynamic devices can be easily adapted to hydrodynamic use. In the following description wherever applicable, reference to an aircraft wing is intended to include reference to a marine craft wing.

The main constraints in aircraft design and in particular to the design of aircraft wings are the aerodynamic drag, space and mass (weight) parameters.

A change of wing shape, varying the camber, permits the optimisation in regard to aerodynamic drag, of a wing section for different flight conditions in particular cruise, takeoff and landing. Early forms of variable camber devices consisted of hinged surfaces at the trailing edge of wings, flaps. Later, it was noticed that creating a slot between the main wing and the moveable surface enhanced the total lift beyond levels achieved by a simple hinged variable camber device. The slot, or gap, has the beneficial effect of energising the upper surface airflow, thus reducing the chance of stall at low speeds.

One form of slotted variable camber device is known as the Variable Camber Krueger flap system. The aerodynamic surface deploys and unfolds from a position under and behind the D-nose of the wing to a position in front of and below the wing. Various improvements on the Krueger system have been proposed but these generally require the use of multiple linkages. One such improvement is discussed in US patent 5,158,252 assigned to The Boeing Company and which discloses a variable camber system having a rotatable drive arm which operates a first and second linkage subassembly.

Another form of slat system is disclosed in US patent 4,753,402 assigned to The Boeing Company and uses tracks and actuators to translate and rotate the slat from a retracted position where it rests directly in front of the main wing to a forward and downwardly deployed position.

Yet another form of slat system is disclosed in US patent 4,360,176 assigned to The Boeing Company. That system utilises a cam track mechanism to deploy a moveable surface from a stowed position to a forward and downwardly extended deployed position.

US Patent 4,202,519 assigned to The Boeing Company discloses a leading edge slat apparatus which utilises a tilting arm having one end pivotally connected to the undersurface of an airfoil and the other end pivotally connected to an actuating member and a tilting link.

US Patent 3,941,334 assigned to The Boeing Company relates to yet another form of variable camber apparatus and describes a hinged rib member and a linkage mechanism to bend and twist the leading edge of the airfoil to contour it into a predetermined curvilinear plot.

Other forms of variable camber leading edge systems are disclosed in US Patents 4,285,482 assigned to The Boeing Company; 4,040,579 assigned to The United States of America; US Patent 2,938,680 assigned to North American Aviation Inc and US Patent 2,406,475 to Gerrit P Rogers and Samuel H Pearls.

Such known slat and Krueger flap systems have a disadvantage in that their size restricts their usage to certain wing types. For example, supersonic aircraft have thin wings which will not accommodate either the known slat or the Krueger flap mechanisms. Further both prior known slat and Krueger flap mechanisms exhibit inefficient load bearing properties because of their thin vertical cross-sections, while both Krueger flap systems and slat techniques suffer from high mass and cost.

Trailing edge slotted variable camber devices rotate an airfoil about a line below and parallel to the wing trailing edge, thus causing both rotation and translation of the aerodynamic surface. This is often achieved through multiple pivot joints, located below the trailing edge of the wing, connecting an extension of the wing to an extension of the aerodynamic surface. Some devices rely on a track attached to the underside of the wing to translate and rotate the surface. Other devices use straight tracks and rotation is achieved through control linkages. Both offset hinge and track devices increase the profile of the wing in the direction of flight during cruise, thus increasing aerodynamic drag and fuel burn.

A disadvantage with the tracked variety of the leading edge and trailing edge systems is that the track pairs used to move the flaps and slats must be interconnected to give redundancy to actuators and to ensure balanced deployment. Considerable care must be exercised in the design of such systems to avoid asymmetric deployment which can cause locking of the mechanism.

It is therefore apparent that the need exists for a compact and simple wing variable leading edge slat and trailing edge flap mechanism which does not increase the profile of the wing during cruise flight and can function whilst one actuator is not working without the need for an interconnecting torque shaft. Such a system must also be structurally efficient so it can bear the aerodynamic or hydrodynamic loads with minimum mass, and achieve the required extension and rotation of the aerodynamic or hydrodynamic surfaces at low manufacturing cost.

Object of the Invention

It is an object of this invention to provide a slotted variable camber device for aircraft and marine craft wings which will minimise the disadvantages of the known systems or at least provide the public with a useful choice.

Disclosure of the Invention

According to one aspect, the present invention comprises a linkage mechanism for varying the deployment of a moveable surface in relation to a wing, said linkage mechanism being characterised in that it comprises:

at least two spaced apart and substantially parallel swing arms, wherein each swing arm has a first end connected to the wing and a second end connected to the moveable surface, whereby the said moveable surface can swing towards or away from the said wing to deploy or retract the said moveable surface, and

at least one control rod which acts between the said moveable surface and a base pivot point associated with the said wing, whereby the moveable surface will also rotate about a span line which is substantially parallel to and below the wing.

Preferably the base pivot point is located on the swing arm.

Preferably the base pivot point is located on the wing.

Preferably the base pivot point is located on a extension to the wing.

Preferably the pivotal connection of the first end of the swing arm to the wing comprises a rotary actuator.

Preferably the moveable surface comprises a slat located at the leading edge of the wing and the second end of each swing arm is connected to the slat by a ball joint.

Preferably the moveable surface comprises a flap located at the trailing edge of the wing and the second end of each swing arm is pivotally connected to a rotation arm which is connected to the flap.

Brief Description of the drawings

Preferred forms of the invention will now be described with the aid of the accompanying drawings wherein:

Fig. 1 shows diagrammatically a plan view of a wing with four slats at the leading edge and two flaps at the trailing edge.

Fig. 2 is a diagrammatic cross sectional view of a retracted slat taken along the line 2 - 2 of Fig. 1.

Fig. 3 is a diagrammatic plan view of the retracted slat shown in Fig. 2.

Fig. 4 is a diagrammatic cross sectional view of a semi-deployed slat as taken along the line 4 - 4 of Figure 1.

Fig. 5 is a diagrammatic plan view of the semi-deployed slat shown in Fig. 4.

Fig. 6 is a diagrammatic cross sectional view of a fully extended slat taken along the line 6 - 6 of Figure 1.

Fig. 7 is a diagrammatic plan view of the fully extended slat shown in Fig. 6.

Fig. 8 is a diagrammatic plan view of an extended flap shown in Fig. 1 with the upper surface of the wing and part of the flap cut away to show the swing and rotation arms, and the control rods at fully deployed position.

Fig. 9 is a diagrammatic cross sectional view of a deployed flap taken along the line 9 - 9 of Fig. 8

Fig. 10 is a diagrammatic plan view of a retracted flap shown in Fig 1 with the upper surface of the wing and part of the flap cut away to show the swing and rotation and the control rods at the retracted position.

Fig. 1 1 is a diagrammatic cross sectional view of a retracted flap taken along line 1 1 - 11 of Fig. 10.

Best Mode of Carrying out the Invention

Referring to the drawings and in particular Fig. 1, the slats 10 are positioned at the leading edge of the wing 11 and the flaps 16 are positioned at the trailing edge of the wing 11. Figs. 2 and 3 are respectively a diagrammatic side elevational view and a plan view of a retracted slat 10 and of a nose section for an airfoil envelope of the wing 11. The slat 10 is attached to the wing 11 by two or more swing arms 12 of which one end is attached through the pivot joints 15 to the wing interface and in the form of the invention illustrated, the other end of each swing arm is attached by means of a ball joint 13 to the underside of the slat 10.

Pivoting of the swing arms 12 about the pivot point 15 will result in the slat 10 moving from a retracted position shown in Figs. 2 and 3, through the intermediate positions shown in Figs. 4 and 5, to the fully deployed position shown in Figs. 6 and 7.

Pivoting of the swing arms 12 about the pivot joints 15 may be actuated by an appropriate means as is known in the art. While in the embodiment shown in the drawings the pivoting of the swing arms is preferably obtained by rotary actuation of the pivot joint 15, other methods of achieving this result can be obtained such as by utilising linear actuators either between the wing 11 and the slat 10 or between the wing 11 and the swing arm 12.

Control rods 14 are utilised to provide the desired rotation of the slats 10 about a span line which is both substantially parallel and below the leading edge of the wing 1 1. The control rods 14 are connected between the slat 10 and a base pivot point by means of bearings 14a and 14b. In a highly preferred form, the base pivot point comprises the bearing 14b and is located on the swing arm 12 and the second bearing 14a is located at a high point on the slat 10. In a modification of the invention the bearing 14b which forms the base pivot point, may be located on the wing 11 or on an extension to the wing.

To achieve aerodynamic lift of the wing during take off and landing, the slat 10 is translated forwards and downwards by the pivoting of the swing arms 12 between the positions shown in Figs. 2 to 7. The restriction of the movement due to the control rods 14 will cause the slat during the translation, to rotate about a span line substantially parallel and below the leading edge of the wing 11. The flaps 16 which are diagrammatically indicated in Fig. 1 as being positioned at the rear of the wing 11, are further diagrammatically illustrated in Figs. 8 through 1 1. As shown in Fig. 8 each flap 16 provides a complete tail section for the aerofoil envelope of the wing 1 1 and is pivotally attached to the wing 11 by two or more swing arms 17 and rotation arms 18. As illustrated, one end of the swing arm 17 is attached to the wing 1 1 through a pivot joint 15 and the other end of the swing arm 17 is attached to a first end of the rotation arm 18 by a pivot joint 21. The second end of the rotation arm 18 is attached to the flap 16 by a pivot joint 20. Rotation of the pivot joint 15 will thus result in the swing arm 17 pivoting so that the flap 16 can move from the fully deployed position shown in Figs. 8 and 9 to the retracted position shown in Figs. 10 and 1 1.

Control rods 19 are utilised to provide the desired rotation of the flaps 16 about a span line which runs substantially parallel and below the trailing edge of the wing 11. The control rods 19 are connected between the flap 16 and a base pivot point by means of bearings 19a and 19b respectively. In a highly preferred embodiment of the invention the pivot point 19b is located on the swing arm 17 and the second bearing 19a is located at a high point on the flap 16. In a modification of the invention the base pivot point may be located either on the wing 1 1 or on an extension of the wing 1 1.

To achieve aerodynamic lift of the wing during take off and landing, the trailing edge moveable surface which is formed by the flap 16 is translated backwards and downwards by the pivoting of the swing arms 17 between the positions shown in Figs. 8 to 11. During translation of the flap, the restriction of the movement due to the control rods 19 will cause the flap 16 to rotate about a span line which is substantially parallel and below the trailing edge of the wing 11.

Optimisation and customisation of the pivot angle rotation of the slat and flap may be achieved by varying the length and position of the control rods 14 and 19.

Having described the invention and its preferred embodiments, it will be apparent that modifications and changes may be made without departing from the spirit of the invention. It is therefore not intended that the words used to describe the invention or the drawing illustrating the invention be limiting and the scope is to be determined solely by the advancement in the art to which the invention relates.

Claims

1. A linkage mechanism for varying the deployment of a moveable surface in relation to a wing, said linkage mechanism being characterised in that it comprises:

2. The linkage mechanism of claim 1, wherein the base pivot point is located on the swing arm.

3. The linkage mechanism of claim 1, wherein the base pivot point is located on the wing.

4. The linkage mechanism of claim 1 , wherein the base pivot point is located on a extension to the wing.

5. The linkage mechanism as claimed in claim 1, wherein the pivotal connection of the first end of the swing arm to the wing comprises a rotatory actuator.

6. The linkage mechanism as claimed in claim 1, wherein the moveable surface comprises a slat located at the leading edge of the wing.

7. The linkage mechanism as claimed in claim 6, wherein the said second end of each swing arm is connected to the slat by a ball joint.

8. The linkage mechanism as claimed in claim 1, wherein the moveable surface comprises a flap located at the trailing edge of the wing.

9. The linkage mechanism as claimed in claim 8, wherein the second end of each swing arm is pivotally connected to an rotation arm which is connected to the flap.