STATIC WING FOR AN AIRCRAFT

This invention relates to aircraft and in particular to a novel design of wing for aircraft.

Various forms of aircraft are known. Where large masses are to be transported or long distances to be travelled, an aeroplane is typically used. It is well known that the lift given to an aeroplane on take off is generated using the Bernoulli principle. Conventional aeroplane wings are static and have an aerofoil shape in cross section, in a typical aeroplane wing, the upper surface is more curved than the lower surface. Consequently, when the wing travels forward through air at speed, the air has further to travel over the upper surface of the wing and sς exerts a smaller pressure than air passing over the lower surface. An upward thrust results from the difference between the two pressures. The leading edge of a conventional aeroplane wing is rounded and the trailing edge relatively pointed.

Rotary wing aircraft are also known, for example helicopters/autogyros. Again the wings have an aerofoil shape in cross section, however, lift is generated by rotating the wings at speed through air rather than moving the whole vehicle forward through air as is the case with aeroplanes.

The firm GFS Projects of the UK (proprietor Mr Geoff Hatton) have recently demonstrated an operational flying saucer proposed to be used as an unmanned aerial vehicle in military reconnaissance. The GFS Projects' vehicle comprises an inverted dome shaped canopy with a centrally located vent and incorporates a single axial fan driven by an electric motor to provide propulsion. A series of flaps at the base of the canopy can be manipulated to affect the air flow over the canopy and thereby control yaw pitch and roll movements of the vehicle. Stators provided on the canopy serve as counter rotation devices and make use of the Coanda effect to provide stability and lift. The Coanda effect is a

B2007/004530

2 widely observed effect; within a certain range of curvatures, a fluid flowing over a curved surface will tend to follow or become entrained by the surface. Thus air flow can, to a limited extent, be directed, this can be used to provide directional lift and stability to a flying object.

The present invention utilises both the Bernoulli and Coanda effects in a substantially ring shaped static wing to which a fuselage can be attached to provide an aircraft of novel configuration.

The static wing of the invention comprises a ring portion having an aerofoil shaped cross section. The leading edge of the aerofoil defines the inner circumference of the ring and trailing edge of the aerofoil the outer circumference of the ring. A diffuser plate is provided over the aperture of the ring portion, the diffuser is larger than the aperture of the ring portion. The diffuser plate has an upper surface whose curvature substantially follows the curvature of the ring portion; the underside of the diffuser plate is similarly curved. Depending on the size and configuration of the wings, the diffuser plate may be rigidly fixed to the ring portion, but desirably is moveable between an open operating position and a closed operating position.

In the open operating position, an air duct arises between the upper surface of the aerofoil and the underside of the diffuser plate. Air flow hitting the underside of the diffuser plate in the open configuration is entrained toward the upper surface of the ring portion spreading across the upper surface and creating lift of the static wing. In the closed operating position, the air duct is closed, the upper surfaces of the diffuser plate and ring portions providing a substantially continuous surface for forward travel.

Air can be directed to the wing from a main power supply via ducting located beneath the wing. The ducting delivers air to the aperture and over the surfaces of the ring portion. When the diffuser plate (which is

situated on the upper side of the wing) is in the open operating position, an air intake duct is opened in the ducting. The air intake is open during lift off (when the diffuser plate is in the open operating position). When the static wing is moving forward and has achieved a reasonable speed, the intake ducting and the diffuser plate will close to enhance the aerodynamic effect across the wing.

Optionally, the ring portion is provided with a plurality of elevators positioned around the outer circumference of the ring portion. These can be manoeuvred to provide extra lift during take off and landing and to control pitch movements of the air craft. Also optionally, the upper surface of the ring portion may be provided with a plurality of ailerons or trim controls spaced radially, and desirably symmetrically, about the upper surface. The ailerons/trim controls may be used to provide roll and banking movements of the air craft and to slow the aircraft on landing. The elevators/ailerons/trim controls may be operated by any known means, including but not strictly limited to pneumatic, electromechanical (fly by wire) or hydraulic means.

Desirably, arranged within the aperture of the ring portion and communicating with the underside of the diffuser plate is an annular diffuser which serves to provide an even flow of air over and under the ring portion. In addition, the diffuser restricts the volume of air in the centre of the wing, thus controlling air flow. The annular diffuser is desirably incorporated into the diffuser plate. By movement of the annular diffuser along its centre axis (which, when the aircraft is in the take off position is substantially vertically disposed) the amount of air passing over the wing can be controllably increased or decreased providing a means of controlling the lift.

The wing of the invention can be propelled by air flow generated by two counter rotating fans or a compressor which force air through the ducting and over the ring portion to provide the lift. Whilst hot essential, the use

of two counter rotating fans is beneficial in that they prevent the need for an anti-torque system. The arrangement of counter-rotating fans supplied by the same power source is achieved by use of a differential gear box. The differential takes power from the engine of the propulsion system and feeds this to two propeller shafts, one is rotated clockwise and the other counter clockwise, counter rotating blades negate the need for tail rotors. It is to be understood, that this is simply one option for propelling the wing of the invention, others of which will no doubt occur to the skilled addressee. Some alternatives include compressors or electrical motors. It will be appreciated that size of airframe will be a limiting factor for some options. In use, the fans are carried in the main fuselage or air frame of the aircraft carried by the wing and are not an essential part of the wing itself.

Due to a small number of moving parts, the wing of the invention can be configured to be removable from an aircraft for ease of transport, maintenance and repair. Various advantages result from the use of the wing of the invention on aircraft. Some of these are summarised below.

The wing enables vertical take off of an aircraft much like a rotary wing aircraft but does not suffer from many of the drawbacks of rotary wing aircraft, for example; retreating blade stall, low speeds, noise, vibration, high maintenance costs due to multiple moving parts and downwash. These features enable aircraft carried by the wing of the invention to be operated from woodland, undergrowth and urban environments and can travel through wooded areas with minimal risk of damage to the static wing, whereas rotary blades would likely be damaged in such applications due to debris interfering with the moving parts of the rotary wing mechanism.

Elevator/ailerons where present in the wing may be connected to the fuselage of the air craft by simple electrical/hydraulic/mechanical or pneumatic connections for operating the diffuser plate and similarly such

connections can be provided to operate the air intake ducts. Such connections can be easily disconnected and consequently, the wing can very easily be detached from the aircraft. This permits easier transport of the craft and simplifies maintenance and repair of the wing or craft.

Thus the invention provides a static wing for use on aircraft that can then be used in environments previously only accessible by rotary wing craft. An aircraft bearing the static wing of the invention has many safety and practical advantages over a rotary wing aircraft.

An embodiment of the invention will now be described in more detail with reference to the following figures in which;

Figure 1 shows schematically an embodiment of a wing in accordance with the invention incorporated with a propulsion system of an aircraft.

Figure 2 shows a face on view of the ring portion of the wing showing one of a number of suitable positions for ailerons/trim controls on the wing.

Figure 3 shows a cross section of an embodiment of a wing of the invention.

As can be seen from Figure 1, a static wing 1 comprises a ring portion 2 having an aerofoil shaped cross section. Positioned above the centre aperture of the ring portion 2 is a diffuser plate 3, the diffuser plate is arranged to be moveable vertically (as shown by the direction arrow) between a closed operational position and an open operational position. In the Figure, the plate is in a partially open position providing an air duct between the underside of the diffuser plate and the upper surface of the ring portion 2. At the outer circumference of the ring portion 2 there are provided a plurality of elevators 4 which are moveable in the directions shown by the arrows. The wing is connected with a propulsion system by means of a mechanical coupling 5.

The propulsion system comprises a pair of counter rotating fans 6a, 6b driven by a jet engine 7 to which they are coupled through a differential gear boxl2. For vertical take off of the aircraft, the diffuser plate 3 is raised into the open operating position and air is drawn through air ducts 8 to the underside of the diffuser plate 3 and directed over the upper surface of the ring portion 2 generating lift. Once the aircraft is in flight and at a substantial forward air speed, the large air intake 8 is closed and the diffuser plate 3 lowered in to the closed operational position and the aircraft travels forward using traditional principles. The air intake for the jet engine is situated on the engine housing. Stability in forward travel is assisted by dwarf wings (not shown) to the rear of the jet engine on the body of the propulsion system.

As can be seen from Figure 1, the propulsion system can be positioned to the rear of an aircraft fuselage and comprises a chamber 6 housing the counter- rotating fans 6a, 6b, jet engines can be symmetrically arranged either side of the chamber 6, a large air intake duct 8 positioned below the chamber 6, just forward of it and aligned centrally with the chamber 6 and fuselage.

Figure 2 shows a face on view of the ring portion 2 including a plurality of elevators 4 arranged adjacent its outer circumference and a plurality of ailerons/trim controls 11. The ailerons are essentially flaps hinged along one edge and are typically maintained in a lowered position where they lie substantially against the surface of the ring portion. They may be lifted individually to varying degrees to assist in the turning, rolling or decelerating of the aircraft. Both the elevators and ailerons are symmetrically arranged about an axis which defines the direction of flight of the wing.

It is to be understood the Figures and foregoing description there of are intended to give examples of possible embodiments of the invention but are by no means the only means of achieving the claimed invention.

Figure 3(a) shows the wing with the diffuser plate in an open operating position. Figure 3(b) shows the wing with the diffuser plate in the closed operating position. It can be seen in the latter case that a substantially continuously curved surface is provided for level flying.