GB2266085A

GB2266085A - Aerofoil construction.

Info

Publication number: GB2266085A
Application number: GB9307662A
Authority: GB
Inventors: Neil Deryck Bray Graham
Original assignee: Composite Technology Pty Ltd
Current assignee: Composite Technology Pty Ltd
Priority date: 1992-04-14
Filing date: 1993-04-14
Publication date: 1993-10-20
Also published as: GB9307662D0

Abstract

An aerofoil constructed from an upper section (19) and a lower section (21) bonded together to define a leading edge spar (23). The two sections (19, 21) are bonded together at the leading edge (11) of the aerofoil along two zones, the first zone (61) extending generally along the exterior surface of the aerofoil and the second zone (62) extending inwardly of the exterior surface. With this arrangement, the first zone (61) is transverse to the mating lines between the two sections (19, 21) and so resists separation of the two sections at the leading edge thereof. <IMAGE>

Description

CONSTRUCTION OF AIRFOILS FIELD OF THE INVENTION THIS INVENTION relates to the construction of airfoils and has been devised particularly, although not solely, for the construction of wings for aircraft.

DESCRIPTION OF PRIOR ART It is known to manufacture wings for light aircraft using composite material including plastics material reinforced with fibre. The construction involves the production of upper and lower wing sections and bonding the sections together at a mating plane, with one or more spars located within the mating wing sections. The skins of the wing sections are of sandwich construction consisting of a generally plantar core of honeycomb or foam material laminated with resin-impregnated fabric. With this arrangement, the wing sections are relatively thin and require careful alignment at the mating plane, otherwise structural rigidity and appearance are adversely affected.

To increase the structural rigidity of the wing at the leading edge thereof, there is provided a leading edge spar. The leading edge spar is generally inserted into position after mating of the two wing sections and is secured to fixing means embedded in the wing sections. The alignment of the two wing sections and the installation of the leading edge spar are time consuming procedures which require careful attention if structural weakness of the wing is to be avoided.

With a view to overcoming these problems, it was proposed in Australian Patent No. 586418 to provide a wing construction formed from two mating wing sections with the leading edge spar being integral with the wing sections.

While this-proposal did prove satisfactory in use, there was some concern that the leading edge spar may be liable to fracturing at the mating plane between the two wing sections in the event of an impact on the wing at the leading edge thereof.

OBJECT OF THE INVENTION The present invention seeks to provide a wing construction which alleviates this concern.

SUMMARY OF THE INVENTION In one form the invention resides in an airfoil construction comprising a first section and a second section bonded together at the leading edge of the airfoil along two zones being a first zone extending generally along the exterior surface of the airfoil and a second zone extending inwardly of the exterior surface.

With this arrangement, the first zone of bonding is transverse to the mating line between the two sections and so resists separation of the two sections at the leading edge of the airfoil.

Preferably, the mating line between the two sections at the leading edge of the airfoil is offset from the mating line for the remainder of the airfoil.

Preferably, the first and second sections are each of composite construction comprising a laminated core and wherein the laminations of the two sections overlap at the first zone of bonding.

Preferably, the second section is formed with a recess for receiving the laminations of the first section at the first zone of bonding.

Preferably, the first section has at the leading edge a core portion forming part of a leading edge spar, the core portion being in cross-section of quadrant shape comprising an arcuate face along the exterior surface of the leading edge of the airfoil and two radial faces one of which extends along the second zone of bonding.

Preferably, the laminations of the first section comprise an exterior skin and an interior skin, the skins being in face to face contact and bonded together at the first zone of bonding.

In one embodiment, the laminations of the second section may comprise an exterior skin and an interior skin, the skins being in face to face contact and bonded together at the first and second zones of bonding.

In another embodiment, the second section may have at the leading edge a core portion forming a further part of the leading edge spar, the core portion being in cross-section of quadrant shape comprising an arcuate face along the exterior surface of the leading edge and two radial faces one of which extends along the second zone of bonding.

In the latter embodiment, the laminations of the second section may comprise an exterior skin and an interior skin, the skins being in overlapping relationship and bonded together along the arcuate face.

The strength of the bond between the first and second sections of the airfoil of this embodiment can be increased by a bridging element bonded to and extending between the radial faces of the two core portions transverse to the second zone of bonding.

The exterior and interior skins of both the upper and lower sections may each comprise one or more layers of fabric formed of any suitable material such as carbon-fibre or kevlar.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood by reference to the following description of two specific embodiments as shown in the accompanying drawings in which: Fig. 1 is a schematic cross-section view of an airfoil construction according to a first embodiment; Fig. 2 is a fragmentary view of an upper section of the airfoil at the leading edge thereof; Fig. 3 is a fragmentary view of a lbwer section of the airfoil at the leading edge thereof; and Fig. 4 is a schematic cross-section view of an airfoil construction according to a second embodiment.

DESCRIPTION OF PREFERRED EMBODIMENTS The two embodiments shown in the drawings are directed to a wing construction for a light aircraft.

The wing according to the first embodiment is shown in Figs. 1, 2 and 3, and comprises a leading edge 11, a trailing edge 13, an upper surface 15 and a lower surface 17. The wing includes an upper first wing section 19 and a lower second wing section 21 bonded together. Formed integrally with the upper and lower wing sections 19 and 21 respectively is a leading edge spar 23, the construction of which is described hereinafter. A trailing edge spar 25 is provided adjacent the trailing edge of the wing and main spar 27 is provided between the leading edge spar 23 and the trailing edge spar 25.

The upper and lower wing sections 19 and 21 are each of composite construction, comprising a core laminated with interior and exterior skins each formed of high strength resin-impregnated fabric. In this embodiment, the core is formed of VENCOR V66 but may be of any suitable core material such as homogeneous cross-linked PVC or urethane foam, or a honeycomb of aramid paper. The skin may be formed of one or more layers of any suitable material such .

as aramid fibre (e.g. kevlarp, carbon fibre or glass fibre.

The core of each section 19, 21 is interrupted to accommodate the main spar 27, as shown in Fig. 1. At the interruption the exterior and exterior skins of the respective wing section are in contact with each other and bonded together. Additional layers of fabric may be provided on the skin at the interruption for strengthening purposes.

The core 31 of the upper wing section 19 is formed in two parts; namely, a first part 33 which forms part of the leading edge spar 23 and a second part 35 which supports most of the upper wing surface 15. The first part 33 extends the full length of the wing and is of across-sectional shape which is best illustrated in Fig. 2 of the drawings. As can be seen, it is of a somewhat quadrant shape, with the arcuate surface 33a thereof extending along, and being shaped to the configuration of, the leading edge 11 of the wing section. The surface 33b of the first part 33 extends inwardly of the wing section, and the surface 33c is substantially perpendicular thereto.

The second -part 35 is in the form of a panel which extends in its longitudinal direction for the full length of the wing and in its transverse direction from the first part 33 to the trailing edge of the wing section. The second part 35 is curved at least on its exposed surface to conform to the profile of the wing surface 15.

The laminate of high strength fabric on the core 31 of the upper wing section comprises two skins, being an exterior skin 41 on the outer face of the wing section and interior skin 43 on the inner face thereof, as best seen in Fig. 2.

With this construction, the upper wing section 19 has a lower face 56 and an inner face 58.

The exterior and interior skins 41 and 43 respectively extend beyond the core 31 at the leading edge where they converge into face to face contact and are bonded together to define an extension portion 45 at the time when the upper and lower wing sections are brought together, as will be explained later.

The laminate of high strength fabric on the core 47 of the lower wing section 21 also comprises two skins, being an exterior skin 48 on the outer face of the wing section and an interior skin 49 on the inner face of the wing section.

The exterior and interior skins 48 and 49 extend beyond the core 47 at the leading edge where they converge into faceto face contact and are bonded together to define an extension portion 51 at the time when the upper and lower wing sections are brought together for bonding.

The extension portion 51 on the lower wing section is set inwardly of the exterior surface of the wing so as to define a recess 53 which can accommodate the extension portion 45 of the upper wing section 19, as will be explained later. Rovings of fabric material are provided below the recess 53 to provide a joggle at 55.

The upper and lower wing sections 19, 21 are formed separately of each other and are brought together in a mould for bonding. The two wing sections meet at a split line which is identified by reference numeral 57 in Fig. 1.

It will be noted that lower face 56 of the upper wing section defined by the core surface 33b of the upper wing section and the portion of the interior skin 43 which covers it, is set above the split line.

When the two wing sections are brought together, the extension portion 45 of the upper wing section is accommodated in the recess 53 provided on the lower wing section. The extension portion 51 of the lower wing section is laid against and bonded to the inner face of the extension portion 45 of the upper wing section and also against lower face 56 on the upper wing section. This provides two zones of bonding at the 'leading edge of the wing; namely a first zone 61 between extension portions 45 and 51, and a second zone 62 between extension portion 51 and lower face 56 of the upper wing section. These two zones of bonding are offset from bonding between the two wing sections at the split line 57 and provides considerable rigidity to the leading edge spar 23.

Furthermore, the first zone of bonding is transverse to the split line between the two wing sections. As a result of this bonding arrangement, there is little (if indeed any) possibility of the wing sections separating at the leading edge in the event of an impact on the leading edge spar.

From the foregoing, it is evident that the first embodiment provides a wing which is of relatively simple construction but which is particularly strong at the leading edge.

There are circumstances where a more robust wing construction may be required. Such a situation may be where a fuel tank is incorporated in the wing. The wing construction according to the second embodiment has been devised for this purpose.

Referring now to Fig. 4 of the drawings, the wing construction according to the second embodiment has an upper wing section 19 and a lower wing section 21, as was the case with the first embodiment.

The upper wing section 19 of this embodiment is similar to that of the first embodiment.

The lower wing section 21 of this embodiment is of more robust construction than that of the first embodiment.

Specifically, the core 70 of the lower wing section 21 is formed in two parts; namely, a first part 71 which forms part of the leading edge spar 23 and a second part 72 which forms part of the leading edge spar 23 and a second part 72 which supports most of the lower wing surface 17. The first part 71 extends the full length of the wing and is of generally quadrant shape, as can be seen in Fig. 4. The first part 71 has the arcuate face 71a thereof extending along, and being shaped to the configuration of, the leading edge of the wing. The surface 71b of the first part 71 extends inwardly of the wing section and the surface 71c is substantially perpendicular thereto.

The second part 72 is in the form of a panel which extends in its longitudinal direction for the full length of the wing and in its transverse direction from the first part 71 to the trailing edge of the wing.

Claims

1. An airfoil construction comprising a first section and a second section bonded together at the leading edge of the airfoil along two zones being a first zone extending generally along the exterior surface of the airfoil and a second zone extending inwardly of the exterior surface.

2. An airfoil construction according to claim 1 wherein the mating line between the two sections at the leading edge of the airfoil is offset from the mating line for the remainder of the airfoil.

3. An airfoil construction according to claim 1 or 2 wherein the first and second sections are each of composite construction comprising a laminated core and wherein the laminations of the two sections overlap at the first zone of bonding.

4. An airfoil construction according' to claim 3 wherein the second section is formed with a recess for receiving the laminations of the first section at the first zone of bonding.

5. An airfoil construction according to any one of the preceding claims wherein the first section has at the leading edge a core portion forming part of a leading edge spar, the core portion being in cross-section of quadrant shape comprising an arcuate face along the exterior surface of the leading edge of the airfoil and two radial faces one of which extends along the second zone.of bonding.

6. An airfoil construction according to any one of the preceding claims wherein the laminations of the first section comprise an exterior skin and an interior skin, the skins being in face to face contact and bonded together at the first zone of bonding.

7. An airfoil construction according to any one of the preceding claims wherein the laminations of the second section comprise an exterior skin and an interior skin, the skins being in face to face contact and bonded together at the first and second zones of bonding.

8. An airfoil construction according to any one of claims 1 to 6 wherein the second section has at the leading edge a core portion forming a further part of the leading edge spar, the core portion being in cross-section of quadrant shape comprising an arcuate face along the exterior surface of the leading edge and two radial faces one of which extends along the second zone of bonding.

9. An airfoil construction according to claim 8 wherein the laminations of the second section may comprise an exterior skin and an interior skin, the skins being in overlapping relationship and bonded together along the arcuate face.

10. An airfoil construction according to claim 8 or 9 wherein a bridging element extends between and is bonded to the radial faces of the two core portions transverse to the second zone of bonding.

11. An airfoil construction substantially as herein described with reference to the accompanying drawings.