Ornithopter

Abstract

An ornithopter includes a fuselage, a wing flapping assembly, a tail control assembly, a tail and a pair of wings. The wing flapping assembly and the tail control assembly are each mounted on the fuselage. The tail is operably connected to the tail control assembly and the position thereof controls the direction of flight and the angle of lift. The wing flapping assembly may have a flapping mode and a glide mode and the wing flapping assembly may include a pawl which is engageable with a cam. In the flapping mode the pawl passes the cam and in the glide mode the pawl engages the cam. Each wing may include a generally triangular inner wing portion and a generally triangular outer wing portion. The outer wing portion may have a plurality of spaced apart battens extending between the diagonal stiffening member and the trailing edge.

Description

FIELD OF THE INVENTION

[0001] This invention relates to ornithopters and in particular remote controlled ornithopters.

BACKGROUND OF THE INVENTION

[0002] Birds and flight have been a fascination of mankind for centuries. Leonardo da Vinci was very interested in flight and is credited with designing one of the first ornithopters. Thereafter many inventors tried to construct mechanical birds with varying degrees of success. Some of the early attempts at man powered aircrafts included flapping wing structures that were powered by bicycles and the like. Later, aircrafts developed along a fixed wing model.

[0003] As noted above many attempts have been made to produce an ornithopter that is reliable and easy to use. For example P. H. Spencer designed an ornithopter that was a basic rubber band powered toy mechanical bird with flapping wings. His designs are covered in U.S. Pat. No. 1,907,887 issued May 9, 1933, U.S. Pat. No. 2,859,553 issued Nov. 11, 1958 and US design patent DES 193,484 issued Aug. 28, 1962. The basic design includes a body, a tail, two main wing spars, a flexible material which makes up the lifting and propelling surface which is extended between the main wing spars and the body of the toy, and a hand wound crank which oscillates the wings. In the latter utility patent Spencer linked the wing motion to the tail which was intended to help with stability in flight. Spencer's designs are simplistic and perhaps satisfactory for a small toy ornithopter but the design could not be adapted for a radio controlled engine powered ornithopter.

[0004] Other similar toy ornithopters are shown in Van Ruymbeke's patents U.S. Pat. No. 4,729,748 issued Mar. 8, 1988 and U.S. Pat. No. 5,163,861 issued Nov. 17, 1992. The latter patent shows a wing lock glide feature to prolong the flight of the model bird after the rubber band power is exhausted. However, neither of these toy ornithopters have a design that could be adapted for a radio controlled engine powered ornithopter.

[0005] Still other designs for ornithopters include full sized man carrying flapping wing aircrafts that use pneumatics with an internal combustion engine as a power source to compress the air used by pistons that actuate the wings. Similarly these designs would be very heavy and expensive to manufacture.

[0006] Accordingly, it would be advantageous to produce a radio controlled ornithopter wherein the direction of flight can be controlled and sustained. Further, it would be advantageous to provide an ornithopter that has a glide mode and a flapping mode and the ability to switch between the two modes. Still further it would be advantageous to provide an ornithopter that has a wing design that provides improved thrust and reduces the drag over prior art wing designs.

SUMMARY OF THE INVENTION

[0007] In one aspect of the invention the ornithopter includes a fuselage, a wing flapping assembly, a tail control assembly, a tail and a pair of wings. The wing flapping assembly and the tail control assembly are each mounted on the fuselage. The tail is operably connected to the tail control assembly and the position thereof controls the direction of flight and the angle of lift. The wing flapping assembly may have a flapping mode and a glide mode and the wing flapping assembly may include a pawl which is engageable with a cam. In the flapping mode the pawl passes the cam and in the glide mode the pawl engages the cam. Each wing may include a generally triangular inner wing portion and a generally triangular outer wing portion. The outer wing portion may have a plurality of spaced apart battens extending between the diagonal stiffening member and the trailing edge.

[0008] In another aspect of the invention the ornithopter includes a fuselage, a pair of wings, a wing flapping assembly and a remote control mechanism. The pair of wings are operably connected to the fuselage. The wing flapping assembly is mounted on the fuselage and is operably connected to the pair of wings wherein the wing flapping assembly has a flapping mode and a glide mode. The wing flapping assembly includes a pawl which is engageable with a cam and in the flapping mode the pawl passes the cam while in the glide mode the pawl engages the cam. The remote control mechanism controls the flapping assembly.

[0009] In further aspect of the invention the ornithopter includes a fuselage, a wing flapping assembly, a tail control assembly and a pair of wings. The wing flapping assembly is mounted on the fuselage. The pair of wings are operably connected to the wing flapping assembly and the fuselage. Each wing has a stiffened leading edge, a trailing edge and a fuselage edge. Each wing includes a generally triangular inner wing portion bounded by the leading edge, the fuselage edge and a diagonal stiffening member and a generally triangular outer wing portion bounded by the leading edge, the trailing edge and the diagonal stiffening member. The outer wing portion has a plurality of spaced apart battens extending between the diagonal stiffening member and the trailing edge.

[0010] In a still further aspect of the invention an ornithopter wing assembly includes a pair of wings. Each wing has a stiffened leading edge, a trailing edge and a fuselage edge. Each wing includes a generally triangular inner wing portion bounded by the leading edge, the fuselage edge and a diagonal stiffening member and a generally triangular outer wing portion bounded by the leading edge, the trailing edge and the diagonal stiffening member. The outer wing portion has a plurality of spaced apart battens extending between the diagonal stiffening member and the trailing edge.

[0011] Further features of the invention will be described or will become apparent in the course of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The invention will now be described by way of example only, with reference to the accompanying drawings, in which:

[0013] FIG. 1 is a perspective view of the ornithopter constructed in accordance with the present invention as viewed from the top;

[0014] FIG. 2 is a perspective view of the ornithopter similar to that shown in FIG. 1 but as viewed from underneath;

[0015] FIG. 3 is a side view of the fuselage of the ornithopter;

[0016] FIG. 4 is a perspective view of the wing flapping assembly of the ornithopter;

[0017] FIG. 5 is a side view of the wing flapping assembly of the ornithopter;

[0018] FIG. 6 is a perspective view of the tail control assembly of the ornithopter;

[0019] FIG. 7 is a perspective view of the tail control assembly of the ornithopter similar to that shown in FIG. 6 but showing a different tail position;

[0020] FIG. 8 is a side view of the tail control assembly of the ornithopter;

[0021] FIG. 9 is a side view of the tail control assembly of the ornithopter similar to that shown in FIG. 8 but showing a different tail position;

[0022] FIG. 10 is a top view of the diagonal rod attachment assembly and a broken away portion of the tail end of the fuselage;

[0023] FIG. 11 is a side view of the diagonal rod attachment assembly and a broken away portion of the tail end of the fuselage;

[0024] FIG. 12 is an enlarged front view of the cam/pawl arrangement of the wing flapping assembly showing the second mircro switch in the normally closed position;

[0025] FIG. 13 is an enlarged front view of the cam/pawl arrangement of the wing flapping assembly showing the second mircro switch in the open position;

[0026] FIG. 14 is a circuit diagram of the wing lever motor for a fuel powered engine; and

[0027] FIG. 15 is a circuit diagram of the reversible electric motor embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0028] Referring to FIGS. 1 and 2, the ornithopter of the present invention is shown generally at 20. The ornithopter 20 of the present invention is a remote controlled mechanical bird. Ornithopter 20 includes a fuselage 22, wings 24, a tail 26, a wing flapping assembly 28 and a tail control assembly 30.

[0029] The fuselage 22 corresponds to the body of a bird. The fuselage 22 is made from high strength lightweight materials. Preferably the fuselage 22 consists of a carbon/epoxy and rohacell foam “sandwich”. The fuselage is cut into the desired shape. The fuselage 22 may have holes 31 cut therein to provide space for the fuel tank 56, tail lift servo 98 (shown in FIG. 3) and the like. The wings 24, tail 26, wing flapping assembly 28 and tail control assembly 30 are all mounted on the fuselage 22.

[0030] Each wing 24 has a leading edge rod 32 along its leading edge and a diagonal rod 34 that extends from the tail end of the fuselage 22 to a point along the leading edge which is approximately one third of the length from the wing tip. Generally each wing 24 is shaped like a bird wing. Each wing 24 is divided into an inner wing portion 36 and the outer wing portion 38. A generally triangular inner wing portion 36 is bounded by the leading edge rod 32, the diagonal rod 34 and the fuselage 22. A generally triangular outer wing portion 38 is bounded by the leading edge rod 32, the diagonal rod 34 and the trailing edge 40 of the wing. Each outer wing portion 38 includes a plurality of battens 42 which are used to stiffen the outer wing portion 38 and provide integrity while allowing flexibility. The trailing edge 40 of the wing 24 is serrated along the trailing edge 40 to simulate feathers. The inner wing portion 36 is the primary lifting surface and the outer wing portion 38 is the primary thrusting surface. The design and construction of the wings 24 provide lift and thrust and are constructed to withstand continuous flapping in flight.

[0031] Each wing 24 has a leading edge sleeve 39. The leading edge sleeve 39 is constructed of heavier durable cloth (preferably Dacron™) as compared to the wing material. Preferably the heavier durable cloth is 3.9 ounce per square meter in weight. This heavier durable material serves to create a generally uniform and generally smooth leading edge across the span of the wings 24. The outside end 41 of each leading edge sleeve 39 has an adjustable closure such that the trim of the wings 24 can be adjusted. Preferably the adjustable closure is a hook and loop type fastener. Any imbalance of wing 24 camber and/or outer wing portion 38 thrusting fin area between the left and right wings of the ornithopter may result in a tendency for the ornithopter to turn in one direction in flight. Adjusting the tension along the leading edge sleeve 39 of the wing 24 varies the camber of the inner wing portion 36 which affects the lift. In addition adjusting the tension along the leading edge sleeve 39 of the wing also varies the tension of the outer wing portion 38 which affects the thrust. The addition of adjustable closures at the outside end 41 of the leading edge sleeves 39 allows the wing tension to be adjusted accordingly and thus provides a means for adjusting the trim.

[0032] The wings 24 (not including leading edge sleeve 39) are of a unitary fabric membrane construction. Preferably the wings 24 are made from ripstop polyester. Preferably it is 1.2 ounces per square meter in weight and is finished with an airtight UV resistant plastic coating. Preferably the fabric membrane is held together with a dry contact waterproof adhesive. The combination results in a very strong construction with no sewn seams. The rods 32 and 34 and the battens 42 are positioned in pockets formed in the fabric membrane. Preferably rods 32 and 34 are constructed from semi rigid pultruded carbon tube and rods. Preferably the battens 42 are constructed of micro carbon. The materials used and the design of the wings 24 as described herein have improved wear resistance for continuous use as compared to the prior art and in particular as compared to prior art shear flexing type wings. Further, the ripstop polyester is an improvement over the more conventional Mylar™ plastic film since Mylar™ has a tendency to become brittle, has a tendency to tear and tends to generate a loud noise if used with larger ornithopters. One advantage of the carbon rods 32 and 34 and micro carbon battens 42 is the high strength to weight ratio of the material in addition to the high degree of thickness. The low weight yet high degree of stiffness of the diagonal rods 34 adds integrity to the wing 24 and enables it to reduce the washout which in turn produces more thrust per wing flap and thus a better climb rate and overall flight performance. Similarly the stiffness of the battens 42 greatly enhances the thrust producing ability of the wing 24. This benefit is not negated by having a large amount of mass behind the leading edge of the wing which may be the case with other non-carbon materials.

[0033] As stated above wings 24 are attached together and are attached to the fuselage 22 with the leading edge rods 32 and diagonal rods 34. Leading edge rods 32 are operably connected to the flapping wing assembly 28 which is described in detail below. The diagonal rods 34 are attached to the fuselage 22 at the tail end thereof with diagonal rod attachment assembly 45 best seen in FIGS. 10 and 11. Diagonal rod attachment assembly 45 includes a round plastic disc 47 and a pair of ball links 49 each attachable to a diagonal rod 34. The round plastic disc 47 is attached to the fuselage 22 with screws 53.

[0034] Tail 26 is constructed in a similar fashion to wings. Tail 26 includes tail side rods 44 and a plurality of tail battens 46. Tail 26 is generally triangular and is bounded by side rods 44 and tail trailing edge 48. As with the wings, preferably the tail is constructed of ripstop polyester sail cloth and dry contact adhesive. The side rods 44 and tail battens 46 are positioned in pockets formed in the fabric membrane. Preferably side rods 44 are constructed from semi rigid pultruded carbon tube and rods and tail battens 46 are constructed from micro carbon. Tail 26 is attached to and controlled by tail control assembly 30 which is mounted on fuselage 22.

[0035] The wing flapping assembly 28 controls the flapping of the wings 24 and has a flapping mode and a glide or locked mode. Referring to FIGS. 3, 4 and 5 the wing flapping assembly 28 includes a drive system 50 and a gear box 52 operably attached to the wings 24. The drive system 50 includes an engine 54 and a fuel tank 56. The engine may be a two stroke internal combustion glow engine with a pull starter and heat sink cylinder head. Alternatively the engine may have an electric starter. As a further alternative the drive system 50 may be a battery pack and an electric motor. Engine 54 is mounted on the fuselage 22 with a rubber well nut soft mounting system 51. This minimizes the engine vibration that is transferred to the fuselage 22.

[0036] The flywheel 58 (best seen on FIG. 3) of the engine 54 is operably connected to the gear box 52 through a centrifugal clutch 60 and a clutch bell 62. Clutch bell 62 has at least a portion with knurled exterior. Gear box 52 is preferably a three stage spur gear reduction box. This type of gear box provides for the high efficiency transmission of power. Preferably the gear box 52 is an open parallel plate gearbox that has a strength to weight ratio. Preferably all of the gear hubs are attached with threaded joints and/or keys and keyways such that the gears can withstand high torque loadings. An engine throttle servo 63 controls the speed of the flywheel 58.

[0037] An output crank 64 is operably connected to the gear box 52. A connecting rod 66 connects the output crank 64 to the wing flapping lever 68 (as best seen in FIG. 4). Wing flapping lever 68 is a “master” lever which drives a slave wing lever 70 by way of intermeshing sector gears. The master/slave arrangement provides for symmetry of wing flapping. Intermeshing sector gear teeth are generated directly onto rod grips for strength and simplicity. The intermeshing sector gears/rod grip have aluminium bearing block inserts to better contain ball bearings than the plastic of the gear/rod. Inserts are press fit into the plastic gear/rod. More specifically the flapping wing lever 68 and the slave lever 70 have a counter bored hole in them for “slip fit” for the leading edge rod 32. The lever/rod grips are also tapped with a larger threaded hole to accommodate the aluminium ferrules glued to the carbon rods. The aluminium ferrules are glued to the rods with approximately one inch of carbon rod extending therethrough. As the ferrules/rods are screwed into the wing lever 68 and slave lever 70 the rod portion slips into the counter bored holes as the threaded portion of the ferrules screw into the threaded holes of the levers. This lets the carbon share the loads instead of placing all the loads on the threaded attachment. Leading edge rods 32 are attached to wing flapping lever 68 and slave lever 70. Preferably each leading edge rod 32 has a threaded aluminum ferrules end on the carbon tube and the threaded aluminum ferrules are screwed into tapped holders on the levers 68 and 70. This allows the users to replace leading edge rods 32 as required. In addition levers 68 and 70 are machined with their gear teeth extending to each end of their sector to allow folding up of the wings with the removal of one bolt from the connecting rod 66. This is for removal of the wings 24 and for ease of transport.

[0038] Output crank 64 has a cam profile which operably engages a ratchet pawl 72. Pawl 72 is held in place with a pawl spring 74. The function of this will be described in more detail below.

[0039] A wing locking assembly 76 is operably connectable to clutch bell 62. Wing locking assembly 76 includes a wing leveler motor 78 that is attached to a wing leveler rocker arm 80. The wing leveler rocker arm 80 has an at rest position and an engage position. The position of the rocker arm 80 is controlled by a wing leveler motor servo actuator 82 and a wing leveler motor off/on micro-switch 84. When activated the wing leveler rocker arm moves the wing leveler motor 78 into the engage position wherein it engages the clutch bell 62 and rotates the clutch bell in the opposite direction to that of the normal flapping. Wing leveler motor 78 engages the knurled portion of the clutch bell 62 and through friction drives the gears in opposite direction. Preferably the wing leveler motor 78 is a 6V D.C. motor that is pivotally mounted with rubber hub 86 on lever rocker arm 80. A battery pack 88 is operably connected to wing leveler motor 78. Preferably battery pack 88 is a Ni-cad battery pack. The wing locking assembly 76 provides intermittent friction drive.

[0040] The gearbox wing lock system of the present invention includes the drive system 50 and the wing locking assembly 76. The gearbox wing lock system allows the flapping wings to stop and lock in place in flight in the desired angle of dihedral suitable for optimum gliding flight. The gearbox 52 is coupled to engine 54 with a centrifugal clutch 60 on the input and a crankshaft mounted on the output end of the gearbox 52. The gearbox 52 is a reduction drive which rotates around its axis. The output crank 64 is connected to a connecting rod 66 which in turn connects to a wing flapping lever 68 of one wing. As the output crank 64 rotates, the connecting rod 66 oscillates the wing flapping lever 68 which in turn oscillates the wing slave lever 70 and thereby flaps the wings.

[0041] The output crank 64 is also a cam which trips a small spring loaded single ratchet pawl 72 during each cycle of rotation. Since the engine powering the craft only runs in one direction, the output of the gearbox also only runs in one direction when the engine is running and the clutch is engaged. The cam action of the output crank 64 therefore trips the spring loaded pawl 72 with each cycle but as the throttle control of the engine is decreased to idle or the engine dies, the centrifugal clutch 60 disengages allowing the geartrain to freewheel. At this point the wing leveler motor 78 with a friction drive hub on its shaft is servo actuated 82 to contact the clutch bell 62 on the engine shaft and it is energized, rotating the clutch bell 62 in the opposite direction as when the engine is running. The friction drive is coupled to the primary stage of the geartrain at the clutch bell thereby attaining high torque in order to cycle the crankshaft of the gearbox in reverse until the ratchet pawl 72 locks the crankshaft in place. The ratchet pawl 72 is positioned such that the cam shaped output crank 64 locks against the ratchet pawl 72 so that the wing flapping assembly 28 holds the leading edge rods 32 in the optimum dihedral for gliding flight. Typically the leading edge rods 32 form an angle of 160° to 180° and preferably the angle formed is 170°. Once the ratchet pawl 72 is locked against the cam shaped output crank 64 the wing leveler motor 78 is de-energized. The wings 24 stay locked in place due to natural wing loading. If idling, the engine 54 can be throttled back up and flapping flight resumed.

[0042] It will be appreciated by those skilled in the art that wing leveller motor 78 polarity can be set up to rotate the output crank 64 in the same direction as normal powered operation and successfully lock the output crank 64 against the ratchet pawl 72 to hold the wings 24 in the glide position. This arrangement brings the output crank 64 cam past the ratchet pawl 72 and requires shut off of the wing leveler motor 78 by the pilots command at the right point in the cranks cycle. (Setting up the motor) Reversing the polarity of the leveler motor 78 and rotating the output crank 64 in the opposite direction provides positive lock-in against the ratchet pawl in less than a single cycle of the output crank 64 however an additional micro-switch is required to shut off the leveler motor 78 immediately as the cam shaped output crank 64 engages the ratchet pawl 72, or else the leveler motor 78 may overheat before the pilot can shut the motor off by radio command. A second normally closed ratchet pawl micro-switch 85 is mounted such that it is only actuated when the contact between the cam shaped output crank 64 and the ratchet pawl 72 is made. The wing leveler motor 78 rotates the output crank 64 in opposite direction of normal powered rotation (counter clockwise as viewed from front). Ratchet pawl 72 is machined with internal groove for thick o-ring. Groove bushing fits inside this o-ring and floats on bolt axle of the ratchet pawl 72. However, when the output crank 64 cam strikes ratchet pawl 72 the o-ring deflects allowing bottom of pawl to trip switch. This instantly opens circuit and stops motion. The normally closed position is shown in FIG. 12 and the open position is shown in FIG. 13. This switch is in the motor 78 circuit and opens the circuit so the motor 78 does not overload. The motor 78 circuit is shown in FIG. 14 at 87. This system will allow the ornithopter to glide with the gas engine running at idle, but does require the remote control pilot or user to switch the wing lock servo back to its original position to open the wing leveler motor off/on micro-switch 84 before throttling the engine 54 back up, otherwise the wing leveler motor 78 would become energized again as soon as the ratchet pawl is unloaded.

[0043] Alternatively rather than a fuel powered engine 54 and a leveler motor 78 a reversible electric motor may be used. In the reversible electric version a similar cam shaped output crank 64 and ratchet pawl 72 are used. A provision to reverse the motor polarity from the pilot's radio command will cycle the output crank 64 back against the ratchet pawl 72. Again, a micro-switch will be tripped to shut off the motor when the cam shaped output crank 64 locks against the ratchet pawl 72. This switch will be devised to only function in the reverse polarity mode. The motor polarity can be reversed back to the original rotational direction and once this is done the shut off switch is by-passed. This allows the wings to be powered up and flapping again after a glide. The second normally closed micro-switch 85 described above and shown in FIG. 13 can be used in conjunction with a reversible electric motor. A circuit diagram for the reversible electric motor is shown in FIG. 15 at 89. A switch 91 is servo activated. It opens and closes two wiring circuits to the motor 93. The first circuit 95 is for normal direction to flap the wings, the second circuit 97 reverses the polarity of the motor to lock the wings against the ratchet pawl. The ratchet pawl micro switch 85 is only in the second circuit 97 and it is switched back to first circuit 95 to resume flying.

[0044] Referring to FIGS. 6 to 9, the position of the tail 26 is controlled by the tail control assembly 90. The position of the tail 26 controls the direction of flight and the lift (assent or descent) of the ornithopter 20. The direction of flight is controlled by the tail rudder servo 92 which is operably connected to the rudder output shaft 94. The tail rudder servo 92 is mounted in a tail servo rocker tray 96. The tail servo rocker tray 96 is a “cradle” type tray. For example the tail 26 can be moved from a generally flat orientation shown in FIG. 7 to an orientation wherein the right side (when facing the nose) of the tail 26 is angled downwardly as shown in FIG. 6. The angle of the tail moves between 45 degrees upwardly above the level with the fuselage to 45 degrees downwardly below level with the fuselage.

[0045] The lift is controlled by the tail lift servo 98 which controls the position of the tail servo rocker tray 96. The tail lift servo 98 is mounted on the fuselage 22. The tail lift servo 98 is attached to a lift rocker ball linkage 100 which in turn is attached to the tail servo rocker tray 96. A pair of top rocker ball linkages 102 and bottom rocker ball linkages 104 are attached between the fuselage 22 and the tail servo rocker tray 96 on opposed sides thereof. The bottom rocker ball linkages 104 are attached to rocker bushings 106. Thus the tail servo rocker tray 96 is supported at four points. The top and bottom rocker ball linkages 102, 104 hold the rocker tray 96 in position which allows it to pivot responsive to the position of the lift rocker ball linkage 100. For example the tail lift servo 98 can move the tray 96 from a position shown in FIG. 9 wherein the tail 26 is generally horizontal to a position shown in FIG. 10 wherein the tail 26 points upwardly. The tail moves between 80 degrees angled upwardly to the right and 80 degrees angled upwardly to the left.

[0046] The tail control assembly 90 facilitates directional control and horizontal stability for the ornithopter while maintaining the appearance, form, and function of the tail of a real living bird. There is no vertical stabilizer like that which is used in most airplanes. Two functions are achieved by the design herein, up and down for lift function and left and right for rudder function.

[0047] The tail lift servo 98 drives the tail servo tray 96 back and forth which rocks the fan shaped tail 26 up and down thus moving the tail 26 to facilitate lift function. The tail 26 is mounted directly to the output shaft 94 of the tail rudder servo 92 which rocks in the tray 96. Therefore the tail 26 can rotate unhindered around the axis of the output shaft 94.

[0048] The tail 26 has a plastic yoke 108 that attaches to the output shaft 94 and the tail side rods 44 are mounted such that they angle from about a 45 degree angle 110 with the axis 112 of the output shaft 94. This causes the trailing edge 40 of the tail 26 to travel in an arc when moved from side to side for rudder function. This greatly enhances the rudder effect. The tail design is very bird-like, lightweight, and effective in controlling the flight of the aircraft.

[0049] The engine throttle servo 63, the wing leveler servo actuator 82, the wing leveler on/off switch, the tail rudder servo 92 and the tail lift servo 98 are remotely controlled through a radio receiver 114 (best seen in FIG. 3). The radio receiver 114 is operably connected to the engine throttle servo 63, leveller servo actuator 82, tail rudder servo 92 and lift servo 98. Radio receiver 114 has a receiver antenna wire 116 attached thereto.

[0050] It will be appreciated that the above description related to the invention by way of example only. Many variations on the invention will be obvious to those skilled in the art and such obvious variations are within the scope of the invention as described herein whether or not expressly described.

Claims

1. An ornithopter for use in association with a remote control device comprising:

a fuselage;

a pair of wings operably connected to the fuselage;

a wing flapping assembly mounted on the fuselage and operably connected to the pair of wings wherein the wing flapping assembly has a flapping mode and a glide mode; the wing flapping assembly includes a pawl which is engageable with a cam, in the flapping mode the pawl passes the cam and in the glide mode the pawl engages the cam;

a remote control means to control the wing flapping assembly.

2. An ornithopter as claimed in claim 1 wherein the wing flapping assembly includes a drive system for driving an output crank which causes a first and second wing flapping lever to move upwardly and downwardly and wherein the first and second wing flapping levers are operably connected to the pair of wings.

3. An ornithopter as claim in claim 2 wherein the drive system rotates the output crank in a first direction and wing flapping assembly further includes a reverse drive system that rotates the output crank in a second opposite direction and whereby rotation in the second opposite direction disengages the cam from the pawl.

4. An ornithopter as claimed in claim 3 wherein the cam is a shaped portion of the output crank.

5. An ornithopter as claimed in claim 4 wherein the first wing flapping lever is operably connected to the output crank and the second wing flapping lever is a slave lever operably connected to the first wing flapping lever.

6. An ornithopter as claimed in claim 3 wherein the drive system is a fuel operated engine and the reverse drive system is a battery operated motor.

7. An ornithopter as claimed in claim 3 wherein an electric motor is the drive system and the reverse drive system.

8. An ornithopter as claimed in claim 3 further including a tail control assembly mounted on the fuselage and a tail operably connected to the tail control assembly wherein the position of the tail controls the direction of flight and the angle of lift.

9. An ornithopter as claimed in claim 8 wherein the tail is generally planar defining a rudder angle between the tail and the fuselage and the tail control assembly includes a tail rudder servo whereby movement of the tail rudder servo causes the rudder angle to change.

10. An ornithopter as claimed in claim 9 wherein the tail control assembly further includes a tail lift servo whereby movement of the tail lift servo causes the tail to move between angling upwardly and angling downwardly relative to the fuselage.

11. An ornithopter as claimed in claim 10 wherein the rudder angle ranges between 80 degrees upwardly to the right and 80 degrees upwardly to the left.

12. An ornithopter as claimed in claim 11 wherein the tail moves between a 45 degree upward angle to a 45 degree downward angle.

13. An ornithopter as claimed in claim 8 wherein each wing has a stiffened leading edge; a trailing edge; a fuselage edge; a generally triangular inner wing portion bounded by the leading edge, the fuselage edge and a diagonal stiffening member; and a generally triangular outer wing portion bounded by the leading edge, the trailing edge and the diagonal stiffening member and wherein the outer wing portion has a plurality of spaced apart battens extending between the diagonal stiffening member and the trailing edge.

14. An ornithopter as claimed in claim 13 wherein a length of the stiffened leading edge is defined by a distance between the fuselage and a wing tip and the diagonal stiffening member extends from a point generally one third of the leading edge length on the stiffened leading edge to a tail end of the fuselage.

15. An ornithopter as claimed in claim 14 wherein the stiffened leading edge includes a sleeve having an adjustable closure, the sleeve extending from the fuselage to the wing tip and a leading edge rod is positioned in the sleeve and the wing flapping assembly includes the leading edge rod and wherein the wing has a tension characteristic and a trim characteristic and whereby adjusting the closure varies the tension in the wing and varies the trim of the wing.

16. An ornithopter for use in association with a remote control device comprising:

a fuselage;

a wing flapping assembly mounted on the fuselage;

a tail control assembly mounted on the fuselage;

a tail operably connected to the tail control assembly wherein the position of the tail controls the direction of flight and the angle of lift;

a pair of wings operably connected to the wing flapping assembly and the fuselage.

17. An ornithopter as claimed in claim 16 wherein the tail is generally planar defining a rudder angle between the tail and the fuselage and the tail control assembly includes a tail rudder servo whereby movement of the tail rudder servo causes the rudder angle to change.

18. An ornithopter as claimed in claim 17 wherein the tail control assembly further includes a tail lift servo whereby movement of the tail lift servo causes the tail to move between angling upwardly and angling downwardly relative to the fuselage.

19. An ornithopter as claimed in claim 18 wherein the rudder angle ranges between 80 degrees upwardly to the right and 80 degrees upwardly to the left.

20. An ornithopter as claimed in claim 19 wherein the tail moves between a 45 degree upward angle to a 45 degree downward angle.

21. An ornithopter for use in association with a remote control device comprising:

a fuselage;

a wing flapping assembly mounted on the fuselage; and

a pair of wings operably connected to the wing flapping assembly and the fuselage, each wing having a stiffened leading edge, a trailing edge and a fuselage edge, each wing including a generally triangular inner wing portion bounded by the leading edge, the fuselage edge and a diagonal stiffening member and a generally triangular outer wing portion bounded by the leading edge, the trailing edge and the diagonal stiffening member, the outer wing portion having a plurality of spaced apart battens extending between the diagonal stiffening member and the trailing edge.

22. An ornithopter as claimed in claim 21 wherein stiffened leading edge includes a sleeve having an adjustable closure, the sleeve extending from the fuselage to a wing tip and a leading edge rod is positioned in the sleeve and the wing flapping assembly includes the leading edge rod and wherein the wing has a tension characteristic and a trim characteristic and whereby adjusting the closure varies the tension in the wing and varies the trim of the wing.

23. An ornithopter as claimed in claim 22 wherein a stiffened leading edge length is defined by a distance between the fuselage and the wing tip and the diagonal stiffening member extends from a point generally one third of the leading edge length on the stiffened leading edge to a tail end of the fuselage.

24. An ornithopter as claimed in claim 23 wherein each wing includes a flapping portion and the flapping portion of the pair of wings are made of one membrane that is reinforced along the fuselage.

25. An ornithopter as claimed in claim 24 wherein each leading edge rod is a pultruded carbon rod, each diagonal rod is a pultruded carbon rod and each batten is a micro carbon batten.

26. An ornithopter as claimed in claim 25 wherein leading edge sleeve is attached to the membrane and the membrane is ripstop polyester and the sleeve is Dacron.

27. An ornithopter as claimed in claim 24 wherein the trailing edge is serrated.

28. An ornithopter as claimed in claim 26 wherein each wing has a shape that corresponds to the shape of a bird wing.

29. An ornithopter wing assembly for use in an ornithopter comprising a pair of wings each having a stiffened leading edge, a trailing edge and a fuselage edge, each wing including a generally triangular inner wing portion bounded by the leading edge, the fuselage edge and a diagonal stiffening member and a generally triangular outer wing portion bounded by the leading edge, the trailing edge and the diagonal stiffening member, the outer wing portion having a plurality of spaced apart battens extending between the diagonal stiffening member and the trailing edge.

30. An ornithopter as claimed in claim 29 wherein stiffened leading edge includes a sleeve having an adjustable closure, the sleeve extending from the fuselage to a wing tip and a leading edge rod is positioned in the sleeve and wherein the wing has a tension characteristic and a trim characteristic and whereby adjusting the closure varies the tension in the wing and varies the trim of the wing.

31. An ornithopter as claimed in claim 30 wherein a stiffened leading edge length is defined by a distance between the fuselage edge and the wing tip and the diagonal stiffening member extends from a point generally one third of the leading edge length on the stiffened leading edge to a tail end of the fuselage.