GB2276131A

GB2276131A - Variable camber vane

Info

Publication number: GB2276131A
Application number: GB9305210A
Authority: GB
Inventors: Malcolm Short
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1993-03-13
Filing date: 1993-03-13
Publication date: 1994-09-21
Anticipated expiration: 2013-03-13
Also published as: GB9305210D0; US5464175A; GB2276131B

Abstract

A variable camber vane 8 comprises a plurality of articulated spanwise segments 25, 26, 27 which can be operated by a mechanism of pivoted links at one end. A plurality of such vanes may be arranged in a supporting frame to act as a variable thrust deflector for the exhaust of a lift engine. In a VTOL or STOVL aircraft installation the vane array is mounted on the underside of the aircraft below a downwardly exhausting lift fan and the range of movement of the variable vane array is used to vector lift thrust between a mainly downward direction and a direction having a substantially rearward component. <IMAGE>

Description

2276131 VARIABLE CAMBER VANE The invention relates to variable camber

vanes. In particular it concerns a mechanism for varying the camber of vanes in an aircraft engine nozzle.

Vertical take-off and landing (VTOL) and short take-off and landing (STOL) aircraft may employ vectorable nozzles and deflect the flow and gas from the propulsion engine. The invention is concerned with aircraft of this kind in which the engine exit nozzles include an array or cascade of vanes to vector engine thrust. Typically each vane in the nozzle array extends between side walls of the nozzle and may be vectorable by means of a multi-part construction. Each vane comprises a leading edge member secured to the side walls of the nozzle and at least one further articulated member by means of which the camber of the vane can be altered.

The object of the present invention is to provide a mechanism for changing the camber of multi-part vanes of the type referred to.

According to the present invention there is provided a variable camber vane comprising a plurality of chordwise members extending span-wise of said vane and including a leading edge member, a trailing edge member and at least one intermediate chord-wise member, said trailing edge member being hinged to said intermediate chord-wise member, said trailing edge member being hinged to said intermediate chord-wise member, and said intermediate chord-wise member being hinged to said leading edge member, an actuator having an output member, first connecting rod means pivotally connected at one end to said output member and at its other end to said intermediate chord-wise member, second connecting rod means pivotally connected at one end to said trailing edge member, and lever means arranged to arcuate displacement about one end and provided at its other end with means for pivotal connection to said second connecting rod means, said lever means being pivotally connected intermediate its ends to said first connecting rod means, whereby movement of said actuator output member in one direction cause the camber of the vane to increase, and movement of said actuator output member in the opposite direction causes the camber of the vane to decrease.

Preferably the actuator is a linear/actuator and the pivotal connection intermediate the ends of the lever may be provided by a pin or by a slide member slidable within a slot formed in the lever.

In a preferred form of the invention there is an array of guide vanes of this type which are interconnected for simultaneous camber change by means of a single mechanism. This array of variable camber vanes may be mounted in a nozzle or duct supplied with fluid from an aircraft propulsion engine. The invention and how it may be carried into practice will now be described, by way of example, with reference to the accompanying drawings in which:

Figure 1 illustrates a vectorable nozzle for a lift fan including an array of guide vanes, Figure 2 illustrates a first embodiment of a mechanism for altering the camber of the vanes in the array, Figure 3 is a cross-sectional view taken along the plane of section line III-III of Figure 2, Figure 4 is a cross-sectional view taken along the plane of section line W-W of Figure 2, Figure 5 illustrates a second embodiment which is a modified form of the mechanism of Figure 2, and Figure 6 is a cross-sectional on line V-V of Figure 5.

Referring first to Figure 1 there is shown at 1 a lift fan which is mounted in an aircraft fuselage with its rotational axis vertical so that the fan draws in air from above the fuselage and exhausts it in a downward direction through an aperture in the underside of the fuselage. In this particular example the fan is rotatably driven by shaft 2 which extends along the aircraft longitudinal axis from the main propulsion engine (not shown). The fan 1 is located within a generally cylindrical housing 3 which is housed in the aircraft fuselage, or possibly within a wing. The fan exhaust aperture on the underside of the fuselage is closeable by a pair of fairing doors 4 hinged to the fuselage underside at 5 and spaced apart laterally on opposite sides of the fan exit aperture. The doors 4 constitute side walls of the fan exit nozzle.

The lower face of cylindrical fan housing 3 is spaced from the lower fuselage skin, that is the doors 4, when in their closed position, and within the space thus created there is an array of nozzle vanes generally indicated at 7. This array comprises a plurality of variable camber vanes 8 mounted in a generally rectangular frame 9, a rear edge 10 of which is pivotally mounted at 12 to the aircraft fuselage. The opposite, forward side of rectangular frame 9 is supported by a folding door arrangement generally indicated at 13. This arrangement consists of two doors 14, 15 which extend across the lateral width of the nozzle between the pair of side doors 4 to form a forward nozzle defining face.

The two parts 14,15 of this folding door arrangement 13 are hinged together at 16 along their transverse abutting edges. The opposite upper edge of the upper door 14 is pivoted at 17 tangentially to the cylindrical fan housing 3. The lower transverse edge of lower door 15 is similarly pivoted at 18 to a forward edge of the nozzle frame 9. The folding door arrangement is deployed to its operating position, as shown by the solid lines in Figure 1, by a linear stroke actuator 19 which has an extendable output shaft 21 pivotally connected at 22 to the nozzle frame 9. When the output shaft 21 is retracted the nozzle frame 9 is raised to the chain linked position shown in Figure 1 and the doors 14,15 fold at pivot 16 into the chain link positions shown at 23,24. With the nozzle in the retracted position the fuselage doors may be closed, by means not shown, to reinstate the smooth underside of the fuselage.

With the nozzle in the deployed position, solid lines in Figure 1, and the fan operating downwardly directed fan air is exhausted through the nozzle formed by the pair of fuselage doors 4, the deployed folding doors 14,15 and the array of guide vanes 8 within frame 9. Therefore, the thrust vector of the fan air may be altered by changing the camber of the vanes 8. The remaining drawings concern alternative mechanisms for achieving this.

Referring now to Figures 2, 3 and 4 there is shown an actuator mechanism for altering the camber of three part variable camber vanes. In the lower part of Figure 2 there is shown a single variable camber vane 8 comprising a fixed leading edge part 25 and pivotally attached thereto a mid-chord vane section 26 and a trailing edge vane section 27. The leading edge section 25 is fixed between opposite side members of nozzle frame 9 and the mid-chord section 26 is pivotally attached about a span- wise expanding axis 28 to the trailing edge of the leading section. The trailing edge vane section 27 is similarly attached about a span-wise extending axis 29 to the trailing edge of the mid-chord vane section 26.

The deflected position of the midchord and trailing edge vane sections are shown at 261,271 respectively by a chain link lines in Figure 2. The angular disposition of mid-chord vane section 26 relative to fixed leading edge section 25 is controlled by a rod 31 one edge 32 of which is journaled to carry the pivot 29 at the trailing edge of the mid-chord vane section. The angular disposition of the trailing edge vane section 27, relative to the mid-chord vane section 26, is similarly controlled by rod 33 which has one end 34 pivotally attached at 35 towards the trailing edge of the trailing edge section 27. The first actuator rod 31 is the principle control member of the variable camber mechanism. Another end 36 of the rod 31 opposite first end 32 is pivotally connected at 38 to an output shaft 40 of an acutator 42. The motion of rod 31 is coupled to rod 33, with an Inherent magnification factor, by means of pivoted lever arrangement generally indicated at 44.

The mechanism 44 comprises a lever 46 which is pivoted at 48 to a fixed axis in the aircraft frame and at its opposite end 50 is pivoted at 52 to one end of rod 33 opposite to the end 34 pivoted to the trailing edge vane section 27. Towards a mid point the lever 44 is connected with rod 31 by means of a sliding pivot. A lever 44 is formed with a rectangular aperture 54 the longitudinal sides of which are engaged by a slide block 56 which is in turn engaged by a pivot pin 58 carried by rod 31. Thus, as rod 31 is moved axially by actuator 42 this movement is transferred to arcuate movement of lever 46 and the sliding block 56 accommodates the non-circular movement of pin 58. The ratio of the distances of pins 52 and 58 from pivot 48 of lever 46 determines the angular magnification factor inherent in the pivotal movement of vane sections 26 and 27. The details shown in drawings Figure 3 and Figure 4 relate to the pivotal connections of lever 46 with rod 33 and rod 31 respectively.

The lever 46 may comprise a double lever, that is it consists of two parallel arms fixed relative to each other but which lie on opposite sides of the two connrcting rods 31,33. The two parts of lever 46 may be riveted together at 60,62 on opposite sides of pivot 48 or they may be connected in some other secure manner, they could be formed integrally. In Figures 3 and 4 like parts carry like references.

So far the variable camber control mechanism has been described with reference only to a single variable camber vane. This vane may be regarded as a master vane and its movement may be transferred to the remaining, or slave, vanes in the nozzle vane array by means of drawbars 64,66 which extend the length of the whole vane array. The first drawbar 64 is interconnected with actuator rod 31 through a common coupling with pivot 29, and is connected with each vane through a coupling with the trailing edge of the mid-chord section, conveniently at the pivot of the trailing edge section. The mid- chord sections of all the vanes in the array are coupled to move in unison. Similarly, the second drawbar 66 interconnects the trailing edge sections of each of the vanes with rod 33 to control, in unison, the angular disposition of each of the trailing edge sections relative to its respective mid-chord section.

Referring now to Figures 5 and 6 there is shown an alternative arrangement for coupling the linear movement of actuator output rod 40 with the two vane actuating rods 31,33. In place of the lever 44, having a sliding block pivoted to rod 31, there is a lever 70, which is again pivoted to aircraft frame at 60, but which is now simply pivoted to both levers 31,33. As in the Figure 2 arrangement lever 70 is pivoted at 52 to one end 50 of rod 33, the opposite end 34 of which is pivoted to the trailing edge vane section 27. The actuator output rod 40 is pivoted to one end 72 of a slightly shorter rod 31, and the pivot in 74 is journaled to the lever 70 for rotation movement only. In order to accommodate the locus of pivot 74 about the axis of pivot 60 on lever 70 the actuator 42 is now pivotally mounted at 76 in order that the actuator output rod 40 may track the curved locus of pivot 74.

The cross-sectional view of Figure 6 shows a section through lever 70 bisecting the three pivots 52,60 and 74. Again, the parts illustrated which correspond to like parts in Figure 5 carry like references.

Coordinated movement of all of the vanes in the array is achieved by the same drawbar arrangement as described with reference to Figure 2. Also, in both arrangements the vane actuating mechanism is mounted on the frame 9. The actuator 42, at least in the form described in the above embodiments, is preferably also mounted on the frame. This need not be the case, however, if some form of flexible drive is substituted for actuator output rod 40 in Figures 2 and 5.

Claims

1 A variable camber vane comprising a plurality of chordwise members extending span-wise of said vane and including a leading edge member, a trailing edge member and at least one intermediate chord-wise member, said trailing edge member being hinged to said intermediate chord-wise member, said trailing edge member being hinged to said intermediate chord- wise member, and said intermediate chord-wise member being hinged to said leading edge member, an actuator having an output member, first connecting rod means pivotally connected at one end to said output member and at its other end to said intermediate chord-wise member, second connecting rod means pivotally connected at one end to said trailing edge member, and lever means arranged to arcuate displacement about one end and provided at its other end with means for pivotal connection to said second connecting rod means, said lever means being pivotally connected intermediate its ends to said first connecting rod means, whereby movement of said actuator output member in one direction cause the camber of the vane to increase, and movement of said actuator output member in the opposite direction causes the camber of the vane to decrease.

2 A variable camber vane as claimed in claim 1 wherein the output member of said actuator is moveable in a linear sense.

3 A variable camber vane as claimed in claims 1 or 2 wherein the pivotal connection intermediate the ends of said lever includes a slide member slidable within a slot in said lever.

4 A variable camber vane as claimed in claim 3 wherein said slide member acts as a bearing for a pivot pin extending from said first connecting rod means.

An exhaust deflector means comprising a plurality of variable guide vanes as claimed in any preceding claim.

6 An exhaust deflector means as claimed in claim 5 wherein said plurality of guide vanes are interconnected for simultaneous camber change to alter a direction of thrust of the exhaust.

7 An exhaust deflector means as claimed in claims 5 or 6 wherein said array is provided in an aircraft thrust deflector system.

8 A variable camber vane as hereinbefore described with reference to the accompanying drawings.

9 An exhaust deflector means including a plurality of variable camber vanes substantially as described with reference to the accompanying drawings.