Patent Application
20180133609
The embodiments presented relate to a self-flapping wing to be incorporated into lightweight toy aircrafts which utilizes passing air around the flexible wings to induce an oscillating flutter-like motion similar to a bird during flight.
Gliding toys have existed in the art longer than the airplanes after which they are typically modeled. Aerodynamic toys such as flying rings, balsa and foam gliders and paper airplanes are typically designed to manipulate the flow of air to produce lift, enhance stability, stay airborne through aerodynamic flight, and may permit further maneuvering.
Gliding toys were originally designed to mock other objects or creatures found in nature, which naturally had the ability to glide. For example, birds, bats, and even maple seeds all utilize the movement of air and air resistance to produce some form of gliding. After the advent of modern aircraft, toy manufacturers began to utilize the same principles of aerodynamics in order to create toys that could glide. Consequently, several toys in the art have attempted to mimic these natural and manmade flying and gliding objects or creatures.
Gliding toys are typically made of light and rigid materials that are able to maintain the designed shape of the gliding surface without unnecessarily weighing the device down making it a hazardous projectile or too heavy to maintain a glide. Typical constructions have used balsa wood for its rigidity and light weight; however, balsa wood is fragile and is incapable of sustaining repeated or severe flexing and oscillation without breaking, especially when it is used in a device the size of most typical toys. Consequently, such rigid materials have made typical gliding toys unable to produce and sustain oscillations that can mimic the flapping motion characteristically exhibited by flying animals like birds.
Previous inventions which have attempted to mimic the motion of a bird's wings have either required several joints and interlocking parts in the wing portion or have resulted in rigid and mechanical imitations of the general up and down motion of a bird's wing as it flaps, remaining rigid along the length of the wing and only moving or flexing at the joint where the wing meets the fuselage, without the ability to embody the organic oscillations along a wing that occur naturally as bird's wing flexes and waves through the air. Consequently, such prior art often fails to achieve the ability for the wings to create glide for the device, or, if they are able to create some glide, fail to mimic the organic movement of a natural wing and require that the fuselage of the device fluctuates in sync with the wings rather than remain stationary.
Additionally, most gliding devices in the art utilize glide to achieve a greater distance when flown, or else they often glide as a byproduct of the other electrical or mechanical systems that create flight. Therefore, these gliding devices often move relatively too fast and travel too far for use indoors or to allow a user to follow alongside the glider at the same pace.
Systems and methods which disclose gliding toys have been known in the art, including U.S. Pat. No. 4,512,690 to Johnson, and U.S. Pat. No. 3,576,086 to Hasley. Further, devices which incorporate various modifications which attempt to mimic the movement of a bird's wings are known in the art, such as U.S. Pat. No. 5,176,559 to Lane. However, there is no single invention or combination which disclose the features provided in the embodiments.
The embodiments described herein provide a single piece self-flapping wing which simulates the fluttering motion of a bird during flight. The device is comprised of a single continuous piece of a light-weight and flexible material designed to be employed on each side of a toy aircraft, with each wing being a mirror opposite of the other, mounted on or incorporated into a toy aircraft, which includes separate additional elements to provide neutral balance and stable flight such as additional horizontal and vertical tails and a weighted nose. During flight, the device is configured to induce structural flutter by causing the self-flapping wings to rapidly transition between the upper and lower positions to control pitch, lift and roll which correspond to the specific dimensions of each wing.
The embodiments further provide flexible light weight highly flexible wings located at the midsection of a fuselage and which enables each of the uniform wings to transition between an upper (i.e., high angle of attack) position which causes the wing to flex up, and lower angle of attack position which causes the wing to flex down as the air flow passes by the wing, decreases to simulate the flutter like bird motion. The wings are comprised generally of three regions: inboard, midspan, and outboard. The inboard region is narrow to promote flexing, and sweeps forward into the midspan region to promote aero-elastic instability, a well-known characteristic of forward swept wings whereby the forward tips tend to swerve up and down in an oscillating fashion. The aft swept outboard region is large and angled back to the extent the flexible thin wing material has inadequate stiffness to hold its shape and oscillates in the passing airflow but short enough that only a fraction of the natural oscillation wavelength is embodied within the boundary of the region, permitting it to change its angle of attack to use the passing airflow to bend the wing up and down in an oscillating fashion like a bird wing.
Lift is produced during repeated dynamic flapping cycles, and it is generated by the flexing that changes the angle of attack to induce the flapping. Thus, if airspeed increases, the forces exerted on the wings increase causing greater flexing and a stronger flapping motion over a larger vertical distance. If airspeed is significantly above the ideal operating forward speed, the forces will be too great, causing the wings to over flex at extreme angles of attack and creating significantly more drag which slows the aircraft down until it reaches a speed conducive to the wings resuming their dynamic flapping. If the craft is moving too slowly or the wings are made too stiff, wing twisting, and flapping may not occur. Thus, the wing size, stiffness, and aircraft weight must be matched such that the natural glide speed of the craft corresponds to an airspeed conducive to the optimal flapping motion that neither over flexes the wings causing drag, stall tuck under the craft, or distorting them out of useful shape, nor so slow that they barely flap or don't flap at all.
During operation, the user may throw or launch a toy aircraft incorporating the self-flapping wings in the same manner as any typical slow, forward gliding aircraft. Horizontal and vertical tails included in such aircraft will continue to function in their usual way, and the toy aircraft would be balanced using the same principles as for a fixed wing gliding airplane. The self-flapping wings will cause the toy aircraft to glide for a shorter distance due to the limited range of the corresponding speed imposed.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
A more complete understanding of the embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:
Any reference to “invention” within this document is a reference to an embodiment of a family of inventions, with no single embodiment including features that are necessarily included in all embodiments, unless otherwise stated. Furthermore, although there may be references to “advantages” provided by some embodiments, other embodiments may not include those same advantages, or may include different advantages. Any advantages described herein are not to be construed as limiting to any of the claims.
As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements.
The embodiments are best understood with reference to the drawings, in which like numbers represent like parts throughout the application. The embodiments illustrated in
Further shown in the preferred embodiment of
Each of the set of self-flapping wings 10 may be curled to further enhance the induced flutter motion or to enhance lift and stability while gliding. The curling in this preferred embodiment further enhances flapping. Curling is required to obtain satisfactory flapping with the alternate embodiment shown in
In one such alternate embodiment, the user may curl the leading edge 324 with a relatively uniform radius of curvature such that the leading edge 324 is angled up or down to enhance oscillation of the naturally structurally unstable forward swept region 325 on each wing. Bending the leading edge 324 down to direct air up causes a slight tucking down force on the leading edge 324. Further, bending the leading edge 324 up will have the opposite effect.
In a further alternate embodiment, the outboard wing region 320 is tipped upward 3 to 6 degrees by imparting a relatively uniform radius bend spanning the space between the dashed lines 326-328 causing airflow to be directed upwards thus causing the outboard wing region 320 to impart a slight trailing edge twisting moment into the narrow forward swept region 325.
A further alternate embodiment would incorporate curling the back edges of the wing tips 329 down 25 to 30 degrees with a uniform radius of curvature between the dashed lines at 330-332 causing airflow to be directed downward and provide an upward reactive force that causes the outboard wing region 320 to be pushed up, by the same known principles that permit a small control surface on the trailing edge 328 of a standard airplane control surface to be moved one way and cause a reaction that moves the larger surface in the opposite direction. The self-flapping wing 10 is flexible and tends to bend upwards causing an excess dihedral angle in flight which degrades the glide performance, gives a steeper glide slope, and results in less time aloft; Thus, it is best embodied with anhedral angle in a relaxed state, wherein it is not flying and is held nose up at an angle of 10 to 15 degrees so that gravity cannot droop the wings. In a further embodiment, the airplane's anhedral angle of its wings is increased up to 30 degrees at the wing base where it joins an aircraft's fuselage, accompanied by an upward dihedral curl of about half the anhedral angle applied as a uniform bend radius between dashed lines 334-336. Laboratory tests of the self-flapping bird wing glider device 10 demonstrated that these combinations of further embodiments noticeably and visibly enhanced wing aero-elastic oscillations.
Another alternate embodiment is shown in
Other devices having shorter wing spans have been used and operated in accordance with these embodiments. It has been found that embodiments with small, short span wings require a thinner wing shape to weaken the material's rigidity and enhance flexibility, and a longer more outboard wing 320 to create an oscillating effect.
It will be appreciated by persons skilled in the art that the present embodiments are not limited to what has been particularly shown and described hereinabove. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope of the following claims.
This application claims the benefit of U.S. Provisional Application No. 62/420615 titled “Self-Flapping Bird Wing” to James D. Zongker filed on Nov. 11, 2017.
| Number | Date | Country | |
|---|---|---|---|
| 62420615 | Nov 2016 | US |
