GB2504369A

GB2504369A - Aircraft wing with reciprocating outer aerofoil sections

Info

Publication number: GB2504369A
Application number: GB1303910.2A
Authority: GB
Inventors: Charl Victor Ranwell
Original assignee: CVR Ltd
Current assignee: CVR Ltd
Priority date: 2013-03-05
Filing date: 2013-03-05
Publication date: 2014-01-29
Anticipated expiration: 2033-03-05
Also published as: GB201303910D0; GB2504369B; GB2504369A9

Abstract

An aircraft wing 10 comprises a fixed wing part 32 for horizontal flight, and a movable wing part 26 having an aerofoil blade 28 at or adjacent to a distal end of the fixed wing part 32 for vertical take-off and landing. A drive element 46 drives the aerofoil blade 28 of the movable wing part 26 on a rapidly repeatable lilt-generation cycle within a plane of the fixed wing part 32. The aerofoil blade 28 of the movable wing part 26, during a lift-generating condition of the lift generation cycle, is extendable from the fixed wing part 32 by the drive element 46 and movable towards a leading edge 56 of the fixed wing part 32. During a resetting condition of the lift-generation cycle the movable wing part is retractable into the fixed wing part 32 by the drive element 46 and movable towards a trailing edge 58 of the fixed wing part 32. With such forward movement of the extended blade 28, there is airflow over its aerofoil surface, thus generating lift. This operation would be used when an aircraft 12 is flying with little or no forward speed, otherwise the blades 28 remain retracted in the fixed wing part 32 and the aircraft 12 flies conventionally. Thus the design allows high speed flight of a conventional heavier-than-air aircraft 12 with one or two sets of such wings 10, and provides high-speed vertical take-off and landing (HS-VTOL) and extended hover capability.

Description

Aircraft Wing This invention relates to an aircraft wing which enables a heavier-than-air aircraft to realise high speed horizontal flight yet with vertical take off and landing (VTOL), and extended hover capability.

Conventional helicopters have a limit on their forward airspeed of around 200 kt (370 km/h) due to reaching a point where the rotor blade that is retreating in relation to forward flight, stalling due to a too low relative airflow over it. Such a retreating blade stall condition leads to buffeting, loss of control, and vibrations that may ultimately destroy the rotor.

The benefit of any high speed vertical take off and landing (HSVTOL) aircraft is that it can travel at high speed and/or for long distances, yet it can take off from and land on a small surface area and it thus does not require a runway for take off and landing, which a conventional high speed aircraft does. Furthermore, if it can sustain periods of extended hover then such a HSVTOL aircraft can facilitate very remote emergency medical and rescue winching and cargo hoisting missions, which conventional helicopters with their limited range cannot.

To date there have been three main commercially viable development routes for HSYTOL aircraft: 1. Jet aircraft capable of conventional high speed flight, and additionally using thrust vectoring whereby the jet engine's blast is deflected or vectored downwards using movable ducts, to provide VTOL. The disadvantages of such aircraft when in the hover are the very high fuel consumption, the requirement for cooling the engine since there is no airflow from forward motion, and the damage the hot downward jet blast can do to especially tarmac surfaces. The now-retired subsonic Harrier jump jet is the most well known but it could not achieve true VTOL at maximum weight and it had to use a ramp for a short take off.

2. Jet aircraft as described abovebut with both thrust vectoring and a ducted vertical thrust turbofan embodied in the wings or in the fuselage, and being shaft driven from the main engine when VTOL is required. The F-35B Lightning is such an example and like the Harrier it cannot sustain extended periods of hover and its YTOL capabilities are used for take off and landing only. It can however attain supersonic forward speed.

3. Tilt rotor aircraft with conventional wings and a large turboprop engine mounted at each wingtip -the complete wing can be rotated on its lateral axis to allow the engines' thrust to be directed vertically for VTOL and hover, or horizontally for forward speed.

Since they are still propeller driven, such aircraft have maximum design speeds of around 270 kt (500 km/h), so they are not that much faster than helicopters. The V-22 Osprey and AgustaWestland AW609 are examples.

Under current development are experimental high speed helicopters which still have conventiona' main rotor systems for VTOL and hover, but they then also have smafi fixed wings and conventional forward facing turboprop engines for high forward speed.

In that flight mode the rotor system is not under power and so there is no retreating blade stall issue as discussed earlier. However, the rotor system still provides drag and IS the maximum speed is in the same region as tilt rotor aircraft. The Eurocopter X3.

Sikorsy X2 and Mu Mi-X1 are examples.

This invention has been designed to overcome the limitations of the aboveinentioned developments and it can offer high speed flight with supersonic possibilities, yet with true VTOL and sustained periods of hover.

In accordance with a first aspect of the present invention, there is provided an aircraft wing comprising a fixed wing part for horizontal flight, a movable wing part having an aerofoil Nade at or adjacent to a distal end of the fixed wing part for vertical take-off and landing, and a drive element for driving the movable wing part on a rapidly repeatable lift-generation cycle within a plane of the fixed wing part, the aerofoil blade of the movable wing part, during a lift-generating condition of the lift generation cycle, being extendable from the fixed wing part by the drive dement and movable towards a leading edge of the fixed wing part, and during a resetting condition of the lift-generation cycle subsequent to the lift-generating condition, being retractable into the fixed wing part by the drive element and movable towards a trafling edge of the fixed wing part.

Preferable and/or optional features of the first aspect of the invention are set forth in claims 2 to 14, inclusive.

According to a second aspect of the invention, there is provided a plurality of aircraft wings in accordance with the first aspect of the invention, the said aircraft wings being in stacked arrangement.

Preferably the stacked alignment is positively or negativdy offset.

According to a third aspect of the invention, there is provided a high-speed vertical take-off and landing aircraft comprising a fuselage; two opposing aircraft wings accordiiig to the first aspect of the invention which extend from the thselage; drive means for providing motive horizontal force to the aircraft; landing gear; elevators ad a rudder.

Preferable andlor optional features of the third aspect of the invention are set forth in claims 19 to 29, inclusive.

In accordance with a fourth aspect of the invention, there is provided a method of providing a high-speed aircraft with vertical take-off and landing capability, the method comprising the steps of providing an aircraft wing in accordance with the first aspect of the invention with a fixed wing part and a movable wing part having an aerofoil blade housable in the fixed wing part, and rapidly rotating the aerofoil blade in a plane of the fixed wing part, whereby the aerofofl blade of the movable wing part moves towards a leading edge of the fixed wing part when extended from the fixed wthg part, and moves towards the trailing edge of the fixed wing part when retracted into the fixed wing part.

Preferably, the rapid rotation of the movable wing part is on an endless arcuate path.

Additionally or alternatively, the movable wing parts may be unidirectionally movable.

The invention will now be more particularly described, by way of examples only, with reference to the accompanying drawings. in which: Figure 1 shows a first embodiment of a diagrammatic heavier-than-air high-speed monoplane aircraft having two opposing aircraft wings in accordance with the present invention; Figure 2 is an exploded view of one said aircraft wing, shown in Figure 1; Figure 3 is a perspective view of the aircraft wing of Figure 2, shown with an aerofoil blade of a movable wing part thngitudinally retracted into a fixed wing part; Figure 4 is an internal of the aircraft wing, showing the aerofoil blade of the movable wing part partially retracted; Figure 5 is a distal end view of the aircraft wing, showing the aerofoil blade of the movable wing part partially extended; Figure 6 is a second embodiment of an aircraft wing. in accordance with the present invention, the fixed wing part being removed for clarity to show two movable wing parts, one with its aerofoil blade partially extended and one partially retracted; Figure 7 is a third embodiment of an aircraft wing, in accordance with the present thvention, and showthg a pitch adjustment mechanism of the movable wing part; Figure 8 is an exploded view of a fourth embodiment of an aircraft wing, in accordance with the present invention and showing oval guide tracks for crank arms of the movable wing part; Figure 9 shows the movable wing part of the fourth embodiment of the aircraft wing assembled and with the movable aerofoll blade extended; Figure 10 is an internal view of the fourth embodiment of the aircraft wing, showing the movable aerofoil blade partially extended; Figure 11 is a perspective view of a fifth embodiment of an aircraft wing, in accordance with the invention, and showing the aerofoil blade of the moving wing part extended; Figure 12 is an exploded view of the aircraft wing, shown in Figure ii and viewing an electric motor per wing, shaft drive and gears, single rotary crank and slider within the fixed wing part wing; Figure 13 is an internal view of the aircraft wing shown in Figure 11, with a movable aerofoil blade at an extended 60 degree position relative to the fixed wing part; Figure 14 is an internal view of the aircraft wing, similar to Figure 13, with the movable aerofoil blade at a partially retracted 120 degree position relative to the fixed wing part; Figure 15 is an internal view of the aircraft wing, similar to Figure 13, with the movable aerofoil blade at a hilly retracted position ISO degree position within the fixed wing part; Figure 16 is an internal view of the aircraft wing, similar to Figure 13, with the movable aerofoil blade at a partially extended 240 degree position relative to the fixed wing part; Figure 17 is an internal view of the aircraft wing, similar to Figure 13, with the movable aerofofl blade at an extended 300 degree position relative to the fixed wing part; Figure 18 shows the movable wing part of the fifth embodiment of the aircraft wing, with the movable aerofoil blade fully extended; Figure 19 is a sixth embodiment of an aircraft wing, in accordance with the present invention, and showing a perspective view from a streamlined distal end with the movaHe aerofoil blade in an extended position; Figure 20 is a seventh embodiment of an aircraft wing, in accordance with the present invention, and showing a perspective view from a distal end having a winglet, the movable aerofoil blade being in a retracted position and a distal access door closed; Figure 21 is similar to the embodiment of the aircraft wing shown in Figure 20, but with the distal access door open and a movable aerofoil blade extended; Figure 22 is an eighth embodiment of an aircraft wing, in accordance with the present invention, showing a vertically stacked arrangement of said wings with negative stagger and an interconnecting winglet at a distal end thereof, the movable aerofoil blades being retracted and distal access doors closed; and Figure 23 is a view similar to Figure 22, but showing the distal access doors open and one movable aerofoil blade extended.

Referring firstly to Figures 1 to 5 of the drawings, in its most basic form, a first embodiment of this invention comprises the wings 10 of a conventional monoplane aircraft 12 with standard flying control surfaces of ailerons 14, elevators 16 and rudder 18, a front mounted engine 20 and tractor propeller 22, and landing gear. As such it flies in a straightforward manner up to its maximum design speed. and it can take off from and land on a runway. However, similarly to a conventional aircraft relying on fixed wings only to provide lift, it cannot remain in the air at speeds below its stall speed utiising the fixed wings, and so in this condition it does not have hover and YTOL capabilities.

Each wing 10 of this aircraft 12 then has contained inside it, a movable wing part 26 having a movable aerofoil blade 28 similar to a conventional heficopter rotor blade.

Each wingtip 30 of a fixed wing part 32 has an open horizontal opening 34 to allow such a blade 28 to extend and move outside of the fixed wing part 32 from rear to front in rdation to it, and to then retract back into the fixed wing part 32 it is contained in.

As the movable aerofoil blade 28 moves forward outside of the fixed wing part 32 there is a flow of air over its aerofoil section and this generates lift. The front to rear movement of the blade 28 happens when it is contained inside the fixed wing part 32, and so there is no reverse airflow over its aerofoil section.

This operation of the blades 28 moving in and out of the fixed wing parts 32 and from back to forward for lift generation when extended, does not require any forward speed of the aircraft 12, and such operation is designed to provide sufficient upwards vertical force by itself to allow the aircraft 12 to hover and take off and land vertically.

Each movable aerofoil blade 28 is affixed to a mechanism of a connecting strut 36 and two rotary crank arms 38 inside the fixed wing part 32, such crank arms 38 rotating on bushings or bearings 39 in the same direction and at the same speed, and each with a balancing weight 40 on the side opposite the attachment to the connecting strut 36 from which the blade 28 extends, to stop vibration. The connecting strut 36 and rotary crank arms 38 allow the blade 28 to continuously move in a circularly outwards, forwards, inwards and rearwards path forming a lift generation cycle.

Thc two rotary crank arms 38 arc in turn sccurcly affixcd to thcir wing's main spar 42 thus allowing the lifting force acting on the blade 28 to be carried through the connecting strut 36, to the rotary crank arms 38. to the main spar 42, and to the rest of thc aircraft 12. Thc two wings' main spars 42 arc adjoincd togcthcr in thc aircraft's fuselage 44.

A secondary fuel driven engine 46 situated in the main fuselage 44 of the aircraft 12 between the two wings 10 and near to the centre of gravity, turns the two sets of rotary crank arms 38 in the two wings 10 through a gearbox 48 and an arrangement of pulleys and V-belts or toothed bells 52. This engine 46 operates independently from the front mounted main engine 20 and forms a drive element of the aircraft wings 10.

The aircraft wings 10, in this embodiment, have been designed without ribs and are preferably of monocoque construction (where the external surfaces support the load) to aflow space for the movable wing part mechanisms of rotary crank arms 38, connecting struts 36. and for the blades 28 to retract into and move rearwards inside the wings 10.

The main spar 42 inside each wing 10 carries the weight and lifting force of the mechanism, and the lower surface of the wing 10 is affixed to the main spar 42. The leading and trailing edges 56, 58 are affixed to the thwer surface, and the top surface of the wing 10 is in turn affixed to the leading and trailing edges 56, 58. This allows lifting forces acting on the wing 10 to be carried through to the rest of the aircraft 12.

There are also preferably end covers 60 for the inner and outer ends of the wing 10 to provide further structural box-like strengthening.

Flaps are not required for the aircraft 12 of this embodiment, since they are main'y used for low speed lift augmentation in conventional winged aircraft, which is not necessary with this aircraft 12 since it has the blade operation therefore. If required for this aircraft 12, the function of flaps to provide drag can be substituted by speed brakes andlor fiaperons. in other words flaps integrated with ailerons 14. Also, the secondary engine 46 can be stopped, so that the blades 28 are fully extended to provide additional lift at low speeds. The drive element may be a secondary electric motor instead of an internal combustion engine, as will be described hereinafter.

The ailerons 14 are of conventional manner except that they are situated on the inboard trailing edges 58 of the wings 10, close to the fuselage 44, whereas they are normally situated outboard for more effectiveness. The ailerons 14 are supported ateraBy by the wings' inncr cnd covers 60 and trailing edges 58. The reason that the ailerons 14 are inboard is to provide more internal space on the outboard part of the wings 10 for the blades 28 to move, and also to allow control in a hover condition, as is explained hereinafter.

There is sufficient internal space available in the inboard section of the wing 10, forward of the main spar 42, for fud tanks and/or retraction of the main wheels of the landing gear.

The aircraft 12 of the invention is controlled during forward flight in a conventional manner by a pilot, preferably using a standard control wheel or column operating ailerons 14 and elevators 16, foot pedals operating the rudder 18, and a throtfle contro' for main engine thrust. In such forward flight mode, the secondary engine 46 is turned off and stopped in a position where the aerofoil blades 28 of each movable wing part 26 are fully retracted into the fixed wing parts 32.

When the pilot has slowed down the forward speed of the aircraft 12 to just above stall by reducing thrust on the main engine 20, and wishes to enter the hover, he initiates starting of the secondary engine 46 and the blades 28 of the movable wing parts 26 start moving and generating lift independently of the fixed wing parts 32, as described above.

When the aircraft 12 is stationary in the hover, then almost all of the lift is generated by the blades 28 and thus the power from the secondary engine 46.

Conversely, when the pilot wishes to translate from the hover into forward flight, the thrust on the main engine 20 is increased until the fixed wing parts 32 of the aircraft wings 10 provide sufficient lift from forward speed, and the secondary engine 46 is then turned off by the pilot and stopped in a position where the blades 28 are again fully retracted into the fixed wing parts 32.

The secondary engine's throttle is preferably operated by an additional floor mounted lever control in the cockpit similar to the collective control in a helicopter, whereby raising it increases revolutions per minute (RPM) on the secondary engine 46 resulting IS in more lift from the blades 28 since the rotary crank arms 38 turn faster and the Nades 28 move faster. Conversely, lowering the control decreases the RPM and lift from the blades 28.

For that operation, the pilot will use the hand he/she normally uses for the main engine's throttle, and so the RPM control lever for the secondary engine 46 may have a twist grip where it is held by the pilot, that also operates the main engine's throttle.

This allows the pilot to control the aircraft 12 during VTOL and hovering with one hand and arm controlling the ailerons 14 and elevators 16, and the other hand and arm controlling the throttles of both main and secondary engines 20, 46.

Note, that in its basic form in accordance with this embodiment, the air-craft 12 does not have variable pitch on the blades 28 as a conventional helicopter does, and so it is the RPM setting on the secondary engine 46 that controls the amount of lift from the hlades 28. An embodiment comprising variable pitch is described hereinafter.

Since the blades 28 when extended move forward in relation to the fixed wing parts 32 and thus the rest of the aircraft 12, there would be a tendency for the aircraft 12 to move rearwards in the air due to the extended Nades 28 pushing forwards against the air mass. An analogy would be in rowing. where the oars are pushed against the water and the boat moves in the opposite direction.

For this reason, the main engine 20 needs to provide some forward thrust to balance that rearward tendency, to allow the aircraft 12 to remain stationary during the hover. Since the main engine 20 is front mounted, this forward thrust provides prop wash or airflow over the elevators 16, rudder 18 and ailerons 14, thus making them effective even at zero forward speed. There is also some lift being obtained from the prop wash over the inboard sections of the wings 10 in such flight mode.

Hence the requirement for the ailerons 14 to be inboard: so that they can be situated in the main tractor engine's prop wash.

During the hover and also with verticai take off and landing, the pilot woirld then control the aircraft 12 as follows: vertical up and down motion using the floor mounted secondary engine 46's RPM control lever; forward/rearward motion and remaining stationary, using the main engine's throttle twist grip control situated on the secondary engine's RPM control lever; banldng to the left or right around the aircraft's longitudinal axis using the standard control wheel or column to operate the ailerons 14; pitching forwards and backwards around thc aircraft's latcral axis using the standard control wheel or column to operate the elevators iô; yawing left or right around the aircraft's vertical axis using the standard foot pedals to operate the rudder 18.

The banking, pitching and yawing are controlled in the same manner as when the aircraft 1 2 is in conventional forward flight, since the respective control surfaces are still effective in the main engine's prop wash even though the aircraft 12 is stationary in the air.

Since the net lifting force or vector from the blades 28 acts direct'y upwards at right angles to the aircraft's lateral and longitudinal axes, banking and pitching of the aircraft 12 in hover and VTOL flight mode will tilt such lift vector in the relevant direction and result in the aircraft 12 moving in the required horizontal direction, similar to a conventional helicopter's main rotor.

H

It is proposed that the controls of this aircraft 12 are very similar iii operation to those of a conventional helicopter, and it would thus be easy for a helicopter pilot to convert to it.

Since this aircraft's wings 10 are mainly intended for high speed flight, it can be designed with its wingspan to be markedly shorter and the all-craft 12 can thus fit into much smaller parking and hangar spaces than conventional aircraft 12 where the wing needs to be larger in area to provide more lift at lower speeds.

When manoeuvring or powering up or down on the ground, the secondary engine 46 can be turned off and stopped in a position where the blades 28 are fully retracted into the fixed wing parts 32, and there is thus no danger of rotationally moving aerofoil blades 28 striking obstacles and people as there is with a conventional helicopter in the same situation.

As vicwcd from thc top, thc right wing's sct of rotary crank arms 38 turn unidircctionally anticlockwisc and thc Icif wing's turn unidirectionally clockwise to move their respective blades 28 forwards when extended. Since they counter-rotate typically in unison, there is no anti-torque force that needs to be countered, as with the requirement for a tail rotor in a conventional helicopter.

Having two engines provides some safety in case of engine failure. If the forward flight main engine 20 fails, the aircraft 12 can be glided to a safe landing area and the secondary engine 46 can then be used for control at very low speeds to allow landing on a spot with no forward motion, compared to a conventional winged aircraft which requires a long flat surface to land on since it still requires forward speed up to the point of landing. If the secondary engine 46 fails during flight, the aircraft 12 can still continue flying using its main engine 20 and then land on a conventional runway.

Instead of being fuel driven, the secondary engine 46 can be an dectric motor. Since the main fud driven engine 20 needs to be providing some forward thrust during a flight mode with no forward speed, it can also use some of its power to turn a generator or alternator which would supply electricity to such a secondary motor, with an onboard battery for storing excess electricity, all forming part of the drive element.

The benefits of a secondary electrical motor compared to a fuel driven engine are: reliability, especially when the aircraft 12 is in the hover or VTOL flight mode and reliant on such a motor/engine to remain aloft; simpler operation especially with regard to engine/motor cooling requirements; finer and more responsive speed control of an electric motor; an electric motor being able to stop in a specific position with far greater simplicity, allowing the blades 28 to be set to fully retracted, or to fully extended if additional lift is required; further safety in that even with completely running out of fud. the aircraft 12 can still be glided and then safely landed due to the battery providing electrical power for control at very low speeds.

There can be a separate secondary dectric motor for each wing 1 0.

Thc bcncfit ovcr a singic clcctric motor for both wings 10 is that thc pilot's control for banking that normally operates the ailerons 14 can then incorporate a differential electric motor speed control thus allowing banking to be achieved by varying the speed of onc wing's clcctrical motor in rclation to thc othcr wing's.

The wing 10 with the motor turning faster would have more lift and thus tend to move vertically upwards in relation to the other wing 10, creating the banking attitude during hover and VTOL flight mode. In this case, the aerofoil blades 28 of the movable wing parts 26 do not necessarily move in unison with each other.

In the case of two electric motors, the ailerons 14 are not required to be in the main tractor engine prop wash, and thus a pusher propeller main engine situated behind the wings 10 can be used instead of a tractor main engine 20, and such pusher engine will still provide airflow over the tail control surfaces for pitching and yawing at zero forward speed.

Having separate electric motors for each wing 10 also facilitates the use of turbofan instead of a propeller driven main engine 20.

Instead of the secondary fuelled engine or electrical motor turning the mechanism of rotary crank arms 38 and connecting struts 36 inside the wing 10 using pulleys 50 and a V-belt or toothed beh 52, a drive shaft 62 and sets of right angled gears 64 can be used instead, as shown in Figures 12 and 18. This has the benefit over pulleys 50 and belts 52 of being more reliable since a belt can break, and of simpler operation since a heft tensioning mechanism is then not required.

The main engine 20 can be a turbofan jet engine instead of a propeller engine, and there could be more than one such main engine as with conventional jet aircraft where they are attached on either side of the rear fuselage 44. In this case, the main engine could still be providing some forward thrust during zero forward speed operations, but there would not be airflow over the tail control surfaces. For that purpose, a small turbine engine could be mounted in the tail of the aircraft 12 with either the complete engine being able to swivel up and down and left and right, or with it being fixed and having a swivel nozzle to deflect the jet blast, similar to VTOL jet aircraft 12. Such swivelling or dcflccting motion would bc linkcd to thc pilot's standard controls for pitching and yawing. Directing the jet blast up or down will allow appropriate pitching, and directing it left or right will allow appropriate yawing when the aircraft 12 is stationary in the air. Such a tail mounted turbine engine could also provide the necessary forward thrust required in zero forward speed operations instead of the main engines, and so its throttle would then be the twist grip on the secondary engine's RPM control lever.

The benefit of having a turbofan jet instead of propeller engines is that high subsonic or supersonic speeds can be obtained during forward flight. Another benefit is that using a tail mounted turbine engine for pitch and yaw control allows it to also fulfil the function of an auxiliary power unit (APU) that many turbine powered aircraft have, to provide power to start the main engines and for electrical power when the main engines are turned off, for air conditioning, lights etc when on the ground.

Referring to Figure 6, a second embodiment of an aircraft wing 10 will now be described. Similar or identical references refer to parts which are the same as those described with reference to the first embodiment, and therefore detailed further

description is omitted.

In this embodiment, two blades 28 and their connecting struts 36 are affixed to the same set of rotary crank arms 38, or to two sets of rotary crank arms 38 on the same axis and mechanism within the fixed wing part 32, and are therefore contained within the same wing 10. The two Hades 28 would then be set 180 degrees apart, in other words, on the two opposite ends of each set of rotary crank arms 38, one above and one below it.

This doubles the lift obtained from a wing 10 but it requires the wing 10 to be thicker to contain both blades 28, and also both blades 28 cannot be fully retracted at the same time since they are 180 degrees opposite to each other on their respective lift generation cycles.

Furthermore, if both blades 28 are affixed to the same set of rotary crank arms 38 then a more complicated mechanism is required since the rotary crank arms 38 cannot have centre axles which would get in the way of the connecting struts 36, and thus they need to be supported on all their sides by rollers or guides.

Two blades 28 per wing 10 do however have the benefit of avoiding the effect of intermittent lift which happens with a single blade 28 where there is no Mt when the blade 28 is moving inside the fixed wing part 32, since with two blades 28 there would then always be a blade 28 extended and moving through the air, generating lift.

Referring to Figure 7, a third embodiment of an aircraft wing 10 is shown whereby angles of attack (AOA) of the blades 28, in other words, the blade pitch, can be varied as the Nades 28 move outside of the fixed wing part 32, by a predesigned fixed setting.

The other parts of the aircraft wing 10 are similar or identical to the preceding embodiments, and therefore similar references are utilised and further detailed

description is omitted.

In this case, the aerofoil of the blade 28 then rotates along its longitudinal axis, in the mechanism of the connecting strut 36 that it is affixed to.

One of the ways to vary the pitch of the Nade 28 is with a castoring wheel 66 attached to the blade 28 itself, which follows a fixed part-circular angled ramp 68 inside the fixed wing part 32.

As the blade 28 moves, such a wheel 66 follows the surface of the ramp 68 resuhing in the aerofoil blade 28 rotating about joint 69 and thus changing the blade pitch depending on requirements.

The angles of the ramp 68 can be designed so that the blade 28 has a higher or a lower AOA at points when partially extended, in other words, when the blade 28 is in the process of extending during a lift-generating condition and retracting during a resetting condition of the lift generation cycle.

The benefit of a higher AOA when partially extended is that, since the blade 28 is moving slower through the air, more lift can be obtained from it compared to when the blade 28 is fully extended. The benefit of a lower AOA when partially extended is a flatter blade 28 to minimise the size of slot or opening 34 required, thus reducing drag.

Changing the blade pitch can also be varied under pilot control as with a conventional helicopter. There is a control mechanism for moving the ramps 68 inside the fixed wing pails.32 on which the castoring wheels 66 attached to the blades 28 run, up or down.

The two wings' ramps 68 can be moved up or down oppositely to each other, in other words, if the one wing's ramp 68 moves up, increasing that blade's AOA and lifting forcc, thc othcr wing's ramp 68 movcs down, dccrcasing that blade's AOA and lifting IS force, thus allowing a banking motion. This ramp allernate movement wouM be Unked to the pilot's control for ailerons 14, and the benefit is that banking ability at zero forward speed can then be controlled by varying one wing's blade pitch in relation to the other wing's, and thus not requiring the rotary crank arms 38 speeds to be varied.

The two wings' ramps 68 may also be moved up and down together, thus simultaneously changing both wings' blades' AOA and lifting force, and allowing control of vertical movement as with the collective in a conventional helicopter. Such combined up and down movement of both wings' ramps 68 would bc linked to the pilot's control lever for the secondary engines' RPM for control of vertical movement.

The additional components required for varying blade pitch add complexity and weight which need to be evaluated against the benefits obtained therefrom.

Once a blade's given acrofoil section has been decided upon during aircraft design, the lift obtained from the blades 28 for a given secondary engine's RPM setting can be increased by a number of design choices. Varying the blade pitch or having two blades 28 on the same set of rotary crank arms 38 has been described. Other design choices relate to the blade size, and/or the blade 28 spending as much of its path outside the fixed wing part 32 when moving forward in relation to its aerofoil, as is possible.

The blade size can be increased in width andJor in length, which increases the surface area of the blade's aerofoil and thus creates more lift. The blade's width is understandably limited by the width of the fixed wing part 32 containing the movable wing part 26 and its aerofoil blade 28. However, since the blade 28 moves in a circular path on the lift generation cycle with its connecting strut 36 following the two rotary crank arms 38, its length is also limited by wing width and wingspan. This is because if the blade 28 needs to fully retract into and extend out of the fixed wing part 32, its length must be the same as the rotary crank arm's length, in other words, the diameter of the circular path. Therefore, the longer the blade length, the longer the rotary crank arm 38 and the wider and longer the fixed wing part 32 containing it all needs to be.

The first design choice would thus be to increase both a width and wingspan of the fixed wing part 32 to accommodate longer rotary crank arms 38.

The blades 28 can also be made to follow an oval path, as shown in Figures 8 to 10 whereby a fourh embodiment of an aircraft wing 10 is shown. Again, like references refer to parts previously described and further description is omitted.

The oval paths of this embodiment allow a longer Nade length to be used for the same fixed wing part width and wingspan, compared to a circular path, yet allowing the blade 28 to still be fully retracted and extended. The mechanism inside the fixed wing part 32 has two fixed oval tracks 70 situated around the axes of the two rotary crank arms 38, and the guides 72 on the rotary crank arms 38 then run in such tracks 70 with sliders 74 in the crank arms 38 themselves, to keep the guides 72 in place. The additional components required for the blade 28 following an oval path add comp'exity and weight which need to be evaluated against the benefits obtained therefrom.

Instead of the blade 28 moving in a circular or oval path following the two rotary crank arms 38 it is attached to, in which in both cases the lateral axis of the blade's aerofoil is always parallel to the wing's lateral axis, the blade 28 can be designed to move on a fan shaped path when viewed from above. Referring therefore to Figures 11 to 18, a fifth embodiment of an aircraft wing 10 will now be described. Again, references to pails previously described are used herein, and further detailed description is omitted.

In this embodiment, there is a slider 76 instead of the inner rotary crank arm 38, which moves in and out along the wing's longitudinal axis in or on a guide 78 affixed to the main spar 42. The blade's arm is then affixed to such a slider 76 and to the outer rotary crank arm 38, which is powered by the drive element, being the secondary engine 46, through belts 52 and pulleys 50, or a drive shaft 62 and gears 64.

Instead of a rectangular shape, the wing tip and its blade slot 34 is preferably of semi- circular shape when viewed from above, to allow the blade 28 to extend at a non-parallel angle to the longitudinal extent of the fixed wing part 32.

With such a fan path, the blade 28 still fully retracts and extends, but due to its longitudinal extent being angularly displaceable rdative to the longitudinal extent of the fixed wing part 32, spends a greater part of its path outside the wing 10, providing for more airflow over its aerofoil and thus more lift compared to a similar sized wing 10 and blade 28 where the longitudinal extent of the blade 28 remains parallel to the longitudinal extent of the fixed wing part 32 when following a circular path during the lift generation cycle.

Referring to Figure 18, there is shown a fifth embodiment of an aircraft wing 10, with the fixed wing part 32 removed for clarity. Again, like references refer to like parts and

further detailed description is omitted.

In this embodiment, the movable wing part 26 includes a drive shaft 62 and sets of right angled gears 64 to provide power from the drive element to the rotary crank arm 38.

The rotary crank arm 38 rotates, causing angular displacement of a fixed length connecting strut 36 having the aerofoil blade 28 at one end therefore and in longitudinal alignment therewith, and the shder 76 at the other end which is slidably received on the drive shaft 62.

Referring to Figure 19, a sixth embodiment of an aircraft wing 10 is now described, again with like references referring to previously described parts. In this case, various enhancements to the wings 10 are possible to reduce drag during forward tlight. For example, the wingtips 30 can be rounded and smoothed which would make them more streanilined and thus have less drag, yet still having the slot 34 for the blades 28 to reciprocate through.

As shown in a seventh embodiment by Figures 20 and 21, the aircraft wing 10 can have a fixed wing part 32 which is fitted with winglets 80. These minimise the lateral movement and loss of air around the wingtip 30 from the area of high pressure below, to low pressure above the fixed wing parts 32, thus giving more lift compared to fixed wing parts 32 without winglets 80. Winglets 80 also prevent wingtip vortices caused by such movement of air, which would cause more drag.

Furthermore, access doors 82 can be situated outside the wingtips 30, which would dose the openings 34 for the blades 28 once the blades 28 have been fully retracted for high speed flight. This causes less drag than if the openings 34 were uncovered. Such access doors 82 when open may lie against the winglets 80 to reduce drag.

If the winglets 80 are at right angles to the wingspan, then the access doors 82 may be shutters to close the openings 34 and minimise drag. Such shutters could then be retracted into the winglets 80 if the openings 34 needed to be uncovered for dep'oyment of the aerofoil blade 28 of the movable wing part 26.

Referring to Figures 22 and 23, there is now described an eighth embodiment of an aircraft wing 10. As before, similar references refer to parts which have been previously described, and therefore further detailed description is omitted.

The aircraft 12 can be designed as a biplane, either with zero, positive or negative stagger of the stacked fixed and movable wing parts 26, 32, and with or without adjoined winglets 80.

Each bi-wing arrangement 84 contains its own movable wing parts 26 having one or more blades 28 housable in the respective fixed wing parts 32, as previously described.

This bi-wing arrangement 84 provides double the lift during forward flight from the fixed wing parts 32, and also during zero forward speed flight from the blades 28 of the movable wing parts 26, compared to a monoplane.

The blades 28 on the top and the bottom wings 1 0 would then extend ahernately, with the benefit of avoiding the problem of intermittent lift experienced with a single wing and single blade 28 as discussed previously.

Each wing 10 may have its own motor for turning its blades 28, or the upper and lower wings 10 on one side could use the same motor, or all four wings 10 could use the same engine or motor. Tn the latter two cases, a drive shaft 62 may connect the mechanism and rotary crank arms 38 of upper and lower wings 10, directly linking either the outboard or inboard rotary crank arm 38, or mounted inside the fuselage 44 and linking the drive pulleys 50 or gears 64 in the fuselage 44 inboard of the wings 10. The drive shaft 62 preferably utilises universal joints if the wings 10 of the bi-wing arrangement 84 have positive or negative stagger.

The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined by the appended claims.

Claims

Claims 1. An aircraft wing comprising a fixed wing part for horizontal flight, a movable wing part having an aerofoll blade at or adjacent to a distal end of the fixed wing part for vertical take-off and landing, and a drive element for driving the movable wing part on a rapidly repeatable lift-generation cycle within a plane of the fixed wing part, the aerofoil blade of the movable wing part, during a lift-generating condition of the lift generation cycle, being extendable from the fixed wing part by the drive element and movable towards a leading edge of the fixed wing part, and during a resetting condition of the lift-generation cycle subsequent to the lift-generating condition, being retractable into the fixed wing part by the drive element and movable towards a trailing edge of the fixed wing part.
2. An aircraft wing as claimed in claim 1, wherein the fixed wing part includes a slot at its distal end through which the aerofoil Nade of the movable wing part is extendable and retractable.
3. An aircraft wing as claimed in claim i or claim 2, wherein, during the lift-generating condition, the drive element moves the aerofoil Nade of the movable wing part on an arcuate path.
4. An aircraft wing as claimed in any one of the preceding claims, wherein, during the resetting condition, the drive element moves the aerofoil blade of the movable wing part on an arcuate path.
5. An aircraft wing as claimed in any one of the preceding claims, further comprising pitch adjustment means for adjusting an angle of attack of the aerofoil blade of the movable wing part during the lift-generating condition.
6. An aircraft wing as claimed in claim 5, wherein the pitch adjustment means comprises a ramp surface on one of the fixed wing part and the movable wing part, and a ramp follower on the other of the fixed wing part and the movable wing part, the ramp surface and ramp follower being cooperable to adjust a position of a leading edge of the aerofoil blade of the movable wing part relative to the leading edge of the fixed wing part.
7. An aircraft wing as claimed in any one of the preceding claims, wherein the fixed wing part includes at least one aileron, and the aerofoil blade of the movable wing part is provided distally of the aileron.
8. An aircraft wing as claimed in any one of the preceding claims, wherein the movable wing part includes a reciprocatable slider within the fixed wing part which is drivable in a longitudinal direction of the fixed wing part. a crank arm which is mounted for rotation within the fixed wing part, and an elongate rigid connecting strut which interconnects the reciprocatable slider, crank arm and the aerofoil blade of the movable wing part.
9. An aircraft wing as claimed in claim 8, wherein the reciprocatable slider is provided on a main spar of the fixed wing part.
10. An aircraft wing as daimed in any one of claims I to 7, wherein the movable wing part includes a belt drive within the fixed wing part which extends in a longitudina' direction of the fixed wing part, two crank arms which are mounted longitudinally of the fixed wing part and which are drivable by the belt drive, and an dongate rigid connecting strut which interconnects the two crank arms and the aerofoil blade of the movable wing part.
11. An aircraft wing as claimed in claim 10, wherein the belt drive is provided on a main spar of the fixed wing part.
12. An aircraft wing as claimed in claim 10 or claim 11, wherein the movable wing part further comprises an arcuate track which is associated with each crank arm for guiding angular displacement of the connecting strut.
13. An aircraft wing as claimed in claim 12, wherein each arcuate track is oval, and each crank arm being length adjustable to accommodate movement of the connecting strut on the arcuate track.
14. An aircraft wing as claimed in any one of the preceding claims, wherein the movable wing part includes two aerofoil blades. whereby the respective aerofoil blades of the movable wing parts are movaNe in unison utilising a common said drive element. 1')
15. An aircraft wing substantially as hereinbefore described with reference to Figures 1 to 5, Figure 6, Figure 7, Figures 8 to 10, Figures 11 to 18, Figure 19, Figures and 21, and Figures 22 and 23 of the accompanying drawings.
16. A plurality of aircraft wings as claimed in any one of the preceding claims, the said aircraft wings being in stacked arrangement.
17. A plurafity of aircraft wings as claimed in claim 16, wherein the stacked alignment is positively or negatively offset.
18. A plurality of aircraft wings substantially as hereinbefore described with reference to Figures 22 and 23 of the accompanying drawings.
19. A high-speed vertical take-off and landing aircraft comprising a fuselage; two opposing aircraft wings as claimed in any one of claims I to 15 which extend from the fuselage; drive means for providing motive horizontal force to the aircraft; landing gear; devators and a rudder.
20. An aircraft as claimed in claim 19, wherein the said drive element of the aircraft wings includes secondary drive means for driving the aerofoil blades of the movable wing parts.
21. An aircraft as claimed in claim 20, wherein the secondary drive means is operable independently of the first said drive means.
22. An aircraft as claimed in claim 20 or claim 2 I, wherein the secondary drive means is at least one of an interna' combustion engine and an dectric motor.
23. An aircraft as claimed in any one of claims 20 to 22, wherein the secondary drive means comprises a drive unit forming the drive elements of the said aircraft wings.
24. An aircraft as claimed in any one of claims 19 to 23, wherein the first said drive means is a tractor propeller engine mounted at a nose of the fuselage.
25. An aircraft as claimed in any one of claims 19 to 23, wherein the first said drive means is a pusher propeller engine mounted behind the said aircraft wings.
26. An aircraft as claimed in any one of claims 19 to 23, wherein the first said drive means is a turbofan jet engine.
27. An aircraft as claimed in any one of claims 19 to 26, ftrther comprising tertiary drive means for providing forced air movement to enable pitch andlor yaw control of the aircraft.
28. An aircraft as claimed in claim 27, wherein the tertiary drive means includes a turbofan jet engine which is pivotably mounted on the aircraft.
29. An aircraft as claimed in claim 28, wherein the tertiary drive means includes a turbo fan engine having one or more movaHe baffles, deflectors or nozzles for directing a discharge of air therefrom.
30. An aircraft as claimed in any one of claims 27 to 29, wherein the tertiary drive means is mounted at or adjacent to a tall of the aircraft.
31. An aircraft substantially as hereinbefore described with reference to the accompanying drawings.
32. A method of providing a high-speed aircraft with vertical take-off and landing capability, the method comprising the steps of providing an aircraft wing as daimed in any one of claims I to 15 with a fixed wing part and a movable wing part having an aerofoil blade housable in the fixed wing part, and rapidly rotating the aerofoil blade in a plane of the fixed wing part, whereby the aerofoll blade of the movable wing part moves towards a leading edge of the fixed wing part when extended from the fixed wing part, and moves towards the trailing edge of the fixed wing part when retracted into the fixed wing part.
33. A method as claimed in claim 32, wherein the rapid rotation of the aerofoil Nade of the movable wing part is on an endless arcuate path.
34. A method as claimed in claim 32 or claim 33, wherein the aerofoil blades of the movable wing parts are unidirectionally movable in unison with each other.