Abstract:
An ornithopter has the capability of slow speed flight as a result of vertical movement of its wings. Two sets of wings are provided with vertical movement of each set of wings 180 degrees out of phase for counterbalancing vertical forces on the fuselage. The direction of the flight path is changed by deflecting the fuselage.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to the field of ornithopters which develop lift and thrust through vertical movement of the wings to develop high aerodynamic propulsive efficiency. Further, the invention includes the provision of changing direction of flight by manipulating a flexible fuselage.  
         BACKGROUND OF THE INVENTION  
         [0002]    There is a long history of aerial vehicles which attain flight through the movement of the wings. Of course, the most successful derivation of this concept is the helicopter. Modern helicopters and conventional aircraft have comparable characteristics of speed, lifting capacity and passenger comfort. These characteristics of the helicopter result from the rotary wing design wherein the wings or blades rotate in a plane parallel with the longitudinal axis of the fuselage.  
           [0003]    In attaining the level of performance of current models, the helicopter has become a very complex machine requiring highly trained pilots. One of the most notable features of the helicopter is the balancing of dynamic rotational forces to attain controllable flight. The torque generated by the rotary wing acting against the fuselage must be managed by the pilot to attain straight and level flight. In addition, the pilot must simultaneously manipulate other flight controls similar to an airplane. Further, if the helicopter loses the function of the vertical tail rotor or ducted fan, which provides critical anti-rotational force, controlled flight is impossible.  
           [0004]    Ornithopters also use a wing drive for flight. In contrast to the rotary wing of the helicopter, the ornithopter has reciprocating wings which move in a plane normal to the longitudinal axis of the fuselage. The ornithopter eliminates the complexity required for overcoming dynamic rotational forces of flight at the expense of flight speed and incidence of reciprocal vibration. However, the lifting capacity of the ornithopter can be substantial and flight operation is less complex than a helicopter.  
           [0005]    Ornithopters can be useful in specialized tasks requiring slow moving observation or lifting or remote flight found in construction, forestry, oil and gas industry, and the military.  
         DESCRIPTION OF THE PRIOR ART  
         [0006]    U.S. Pat. No. 6,206,324 to Smith discloses an ornithopter with multiple sets of computer controlled wings which may be programmed to reciprocate in various combinations. The angle of attack of the wings is controlled throughout each reciprocation to provide optimal lift and minimal drag.  
           [0007]    The Michelson patent, U.S. Pat. No. 6,082,671, is an attempt to teach the concept of a mechanical insect. The wings are twisted, to optimize lift, during reciprocation by rotation of the wing spar.  
           [0008]    A toy ornithopter is disclosed in U.S. Pat. No. 4,155,195. The two sets of wings of the device are mounted on the fuselage in a vertically overlapping design. The sets of wings are reciprocated by crank arms oriented at 90 degrees to each other and powered by a rubber band. The sets of wings reciprocate out of phase with each other in that as one set moves downwardly the other set is moving upwardly. The flight path is preset by adjusting the empennage before flight.  
           [0009]    What the prior art lacks is an ornithopter with a simple drive system for the wings and a flexible fuselage that can control direction of flight.  
         SUMMARY OF THE INVENTION  
         [0010]    Accordingly, it is an objective of the instant invention to teach an ornithopter having vertically moving wings for lift and thrust with a bending fuselage for flight path control.  
           [0011]    It is a further objective of the instant invention to teach the use of a pivoting power beam linked to a power source and the wings for reciprocating the wings.  
           [0012]    It is yet another objective of the instant invention to teach damping vertical vibration by counterbalancing the forces generated by the wings.  
           [0013]    It is a still further objective of the invention to teach flight path control by moving the center of gravity.  
           [0014]    It is another objective to teach the controllability of the vehicle at slow speeds, well below stall speed of fixed wing aircraft and below the speed at which a conventional empennage is effective, by flapping wings for lift and thrust and by moving the center of gravity in flight.  
           [0015]    It is another objective of the invention to teach that the force required to support the lift of the front set of wings is counterbalanced by the force of the aft set of wings.  
           [0016]    Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. 
       
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0017]    [0017]FIG. 1 is a perspective of the ornithopter of this invention showing relative direction of movement of the wings in phantom lines;  
         [0018]    [0018]FIG. 2A is a side view, partially in section, of the forward fuselage and wing mounts in one phase of reciprocation;  
         [0019]    [0019]FIG. 2B is a side view, partially in section, of the forward fuselage in the phase of flight shown in FIG. 1;  
         [0020]    [0020]FIG. 3 is a perspective of the invention showing deflection of the aft fuselage in phantom lines;  
         [0021]    [0021]FIG. 4A is a plan view, partially in section, of the control system for deflecting the aft fuselage;  
         [0022]    [0022]FIG. 4B is a plan view, partially in section, of the control system deflecting the aft fuselage for a right turn;  
         [0023]    [0023]FIG. 4C is a plan view, partially in section, of the control system deflecting the aft fuselage for a left turn;  
         [0024]    [0024]FIG. 5 is a plan view of a bracket for the control system;  
         [0025]    [0025]FIG. 6 is a perspective of the ornithopter of this invention with an empennage; and  
         [0026]    [0026]FIG. 7 is a perspective of a wing panel of this invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]    The ornithopter  10  has a fuselage  11 , wings  12  and landing gear  13 , as shown in FIGS. 1, 3, and  6 . The fuselage  11  has a rigid forward portion  14  and a flexible aft portion  15 . A passenger compartment (not shown) and/or a load carrying apparatus (not shown) would be attached to the rigid forward fuselage  14  in a conventional manner. A power source  16 , by way of illustration, is shown in FIGS. 2A and 2B, as mounted within the forward fuselage  14 . However, the power source may be mounted in other locations on the vehicle. Also, the power source is shown as a generator but any type of motor may be used, including fuel burning reciprocating engines, turbines, fuel cells, batteries or others.  
         [0028]    The power source  16  drives a fly wheel  17  through a belt  18  and cooperating pulleys  19  and  20 . Of course, the belt could be a chain and the pulleys could be sprockets, as a matter of choice. Also, a drive shaft could be used in place of the belt, with bevel gears, to drive the fly wheel  17 .  
         [0029]    The fly wheel  17  has an eccentrically mounted pin  21  connected to a drive link  22 . Journal  23  permits drive link  22  to rotate around the pin  21  during rotation of the fly wheel. Another journal  24  is in the other end of the drive link  22 . Journal  24  rotatably connects the drive link to the power beam  25 . This arrangement results in reciprocation of the power beam in response to the rotation of the fly wheel. As an alternative (not shown), the power beam could be reciprocated by solenoids acting on the end(s) of the beam.  
         [0030]    The power beam  25  is mounted on the rigid forward fuselage by a pin  26  located intermediate the length of the beam. As the drive link  22  reciprocates, the power beam  25  pivots about pin  26 . As can be seen in FIGS. 2A and 2B, the drive link  22  attaches by journal  24  to the power beam  25  nearer one end to provide the reciprocation of the beam. A pin  27  is located on power beam  25  near the journal  24 . The pin fits into a rotating journal on connecting link  28 . Connecting link  28  rotatably connects power beam  25  and wing mount  29  through journal  30 . This link smoothly transfers the reciprocating force of power beam  25  to the front set of wings  31 .  
         [0031]    The other end of power beam  25  includes pin  32  journaled into rear connecting link  33  for rotational movement. The rear connecting link  33  is rotatably connected to journal  34  on rear wing mount  35  by pin  36 . Rear wings  35  are connected to the wing mount  35 . As power beam  25  pivots about pin  26 , the front set of wings move in one direction while the rear set of wings move in the opposite direction. The opposite movement of the sets of wings counterbalances the reciprocating forces on the fuselage and provides smooth flight. As can be seen by a comparison of FIGS. 2A and 2B, the distance of the throw of the ends of power beam  25  is equal. However, the additional linkage on the front wings dampens the transition of the change of direction of the wings.  
         [0032]    Stationary shaft  37  is mounted on the forward fuselage  14  between the forward set of wings and extends vertically normal to the longitudinal axis of the fuselage. The wing mount  29  slidably engages the shaft  37  and moves along its length during reciprocation of the wings. The wing mount  29  carries journals  38  and  39  which rotatably connect to wing spars  40  and  41  of forward wings  42  and  43 .  
         [0033]    Rear stationary shaft  44  is mounted on the forward fuselage between the rear set of wings and extends vertically normal to the longitudinal axis of the fuselage. The wing mount  35  slidably engages the shaft  44  and moves along its length during reciprocation of the wings. The wing mount  44  carries journals  45  and  46  which rotatably connect to wing spars  47  and  48  of the rear wings  49  and  50 .  
         [0034]    The lift force of the forward set of wings supported by pin  27  of beam  25  is counterbalanced by the lift force of the rear wings at pin  32  of beam  25 .  
         [0035]    Both the rear and front sets of wings have a rotating connections  38 ,  39 ,  45  and  46  to the wing mounts  29  and  35 , respectively, which also smooth out the reciprocating vibration forces.  
         [0036]    In this manner, the pivoting of the power beam  25  drives the wing mounts  29  and  35 , in opposite directions, translating the vertical movement to the flapping of the forward wings  42  and  43  with the rear wings  49  and  50 .  
         [0037]    In FIG. 3, the deflection of the flexible rear fuselage  15  is illustrated as a lateral movement of the free end of the fuselage in the yaw axis of the vehicle. In the slow flight regime of the ornithopter, a shift in the center of gravity coupled with asymmetrical increased drag will change the flight path. The deflection of the flexible fuselage is not severe enough to cause permanent bending or structural damage of the rear fuselage. The rear fuselage will tend to return to the longitudinal axis upon relief of the control input. The rear fuselage is made up of a central longeron  51  made of a material with a desired moment of elasticity and strength. The longeron is connected at one end  52  to the rigid fuselage  14  and the free end  53  is connected to the surrounding control elements  54 ,  55 ,  56  and  57 .  
         [0038]    As shown in FIGS. 4A, 4B, and  4 C, the control bar  58  is connected on a plate  59  mounted on the forward fuselage  14 . The bar  58  has a center pin  60  which forms a rotatable connection with an aperture in the plate  59 . Control input may be applied through the center pin  60  or through the ends of the control bar  58 . In the FIGS., the bar  58  is rotatably connected at  61  and  62  to the lateral control elements  54  and  57 , respectively, for deflection in the yaw axis. Control elements  55  and  56  may be in the form of longerons or may be rotatably connected to another control bar (not shown) oriented at 90 degrees to the control bar  58  to operate the control elements in the pitch axis. The control elements may be in the form of control cables or control rods. To maintain spatial orientation of the control elements and the longeron  51 , a series of brackets  63  are attached along the length of the longeron  51 . The brackets have apertures through which the control elements pass.  
         [0039]    In the modification shown in FIG. 6, the aft fuselage is provided with an empennage  64  with aerodynamic control surfaces  65  in the yaw axis and  66  in the pitch axis for added stability and control of the ornithopter at higher speeds. The control surfaces  65  may include movable rudders (not shown) and/or fixed trim tabs on the trailing edges. The control surfaces  66  may include movable elevators (not shown) and/or fixed trim tabs on the trailing surfaces.  
         [0040]    In order to more closely mimic the efficiency of a bird&#39;s wing, the ornithopter has control of the angle of attack and the twist of the wings through each cycle. Each of the wings  12  of the ornithopter  10  has a flexible wing surface  67  in the nature of a sail. The wings surface  67  has a leading edge  68 , a foot  69 , and a trailing edge  70 . The leading edge and the trailing edge intersect at the tip  71  opposite the foot  69 . The leading edge of the wing surface is attached to the wing spars of the of the wings  12 . As shown in FIG. 7, the wings surface  67  is attached to wing spar  41  of the front set of wings. The foot  69  of the wing surface forms the wing root and includes a batten  72  extending from the leading edge  68  to the trailing edge  70  for stiffening the wing surface material. To provide more shaping to the wing surface, battens  73 ,  74  and  75  are spaced from the foot to the tip. The battens may be made from any light weight material that has the requisite flexibility and strength to reinforce and hold the desired shape of the wing surface.  
         [0041]    To provide adjustability of the twist in the wings a down haul  76  is attached to the foot of the wing surface and extends parallel to the spar. Added tension on the down haul  76  tends to flatten the wing surface longitudinally. Such a control input is related to an increase in the relative wind speed. An vang  77  is attached to the batten  72  near the trailing edge of the wing surface and extends to the spar. By increasing the tension on the vang  77 , the twist of the wing surface is flattened laterally. These control inputs could be set before flight or operated by flight controls during flight. In any event, the angle of attack of the wings and the drag may be adjusted by adjusting the twist of the wings.  
         [0042]    It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement of parts herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification and drawings.