Aeronautics and astronautics – Aircraft – heavier-than-air – Airplane and fluid sustained
Reexamination Certificate
2003-06-30
2004-09-21
Poon, Peter M. (Department: 3643)
Aeronautics and astronautics
Aircraft, heavier-than-air
Airplane and fluid sustained
C244S00400R, C244S04500R, C446S034000
Reexamination Certificate
active
06793172
ABSTRACT:
FIELD OF THE INVENTION
The subject invention is a toy aircraft which is designed for remote controlled slow flight, indoor or in a small outdoor yard or field. The aerial lifting body is comprised of a series of lightweight planar or thin airfoil surfaces arranged in a radially symmetrical configuration around a central cavity. A preferred embodiment is a diagonal cube. Suspended within the cavity is a thrust generating propeller system which can be regulated remotely so as to change the angle of the thrust vector within the cavity. Lifting, stability, turning, and general control of the direction of motion in flight is accomplished without any formal wings, rudder, tail, or control surfaces.
There has been a great interest recently in indoor toy aircraft which are small in size yet capable of making remote controlled flight (Radio Control Microflight March 2000 publishers Model Airplane News www.rcmicroflight.com). By necessity such aircraft must be lightweight and have a high degree of inherent stability. They also must be compact in size and design. Long extended wings and tail structures can reduce the maneuverability of the aircraft for indoor areas or small outdoor fields. Extended fragile control surfaces are also vulnerable to damage during crashes.
The first technologic objective of the invention is to provide a lightweight toy aircraft which is compact in size and shape, which is relatively crash-proof and contains an enclosed propeller system, is without extended wings or tail, yet which has a high degree of inherent flight stability, and a high degree of lift to sustain flight at low speeds. The second objective is to provide a very slow flight toy aircraft with an extremely low aspect ratio and a large dihedral so as to provide stability in yaw and lateral direction. The third objective is to provide a very slow flying toy aircraft which can be controlled in flight and can be turned in a small radius without loss of altitude, without any moving control surfaces such as rudder, ailerons, elevators or elevons. The fourth objective is to provide very light weight lift generating surfaces which are internally self-braced under tension and compression. The fifth objective is to provide a means of flight direction control using enclosed thrust vectoring control solely within the center enclosed cavity of the aircraft. Thrust vectoring is superior to moveable control surfaces at very low speed. A sixth objective is to provide a thrust vectoring means which uses only one propeller and does not require blade pitch control.
BACKGROUND OF THE INVENTION
The present radio controlled toy aircraft invention combines a compact lightweight lifting body with a single propeller vector control to achieve stable very slow flight with a high degree of radio control maneuverability in a small flight area.
Conventional control of slow flight aircraft uses large control surfaces such as elevators, rudders and ailerons or elevons. Because of the slow velocity, large area control surfaces are needed in slow flight. In addition, to achieve adequate lift at slow indoor flight velocities, large wing surfaces areas relative to total weight are required.
In the prior art of radio controlled toy aircraft, control of aircraft direction has been achieved without moveable rudder or elevators using multiple independently controlled motors and propellers (Shugo U.S. Pat. No. 5,087,000, Palieri U.S. Pat. No. 3,957,230, Kress U.S. Pat. No. 4,198,779, Yamamoto et al U.S. Pat. No. 4,760,392, Hansen et al U.S. Pat. No. 4,143,307). In such prior art the aircraft has a conventional wing and tail with horizontal and vertical tail or stabilizing wings. Two motor driven propellers at opposite sides of the central fuselage in the prior art are independently controlled to provide a relative difference in thrust velocity. A higher power applied to the propeller on one side causes the wing on that side to rotate toward the center line and to move at a higher velocity compared to the opposite retreating wing side. This results in a bank of the aircraft because the slower moving opposite wing has less lift. Without a separate control surface to attain horizontal and lateral stability, the control of turning using two independent motors and a conventional wing must therefore be done with skill to avoid a downward spiral resulting in a crash. For the prior art this limits the flight performance to gentle slow turns with a required maneuver after the turn to recovery from the bank by increasing power to gain altitude.
In the prior art tailless aircraft have required airfoils which do not have nose-down pitching moment. In a tailless aircraft such moment can not be counteracted by a horizontal tail which is at some distance behind the center of gravity (Lennon Andy, Basics of R/C Model Aircraft Design, Publisher Air Age Inc. 1996 ISBNO-911295-40-2). Highly cambered airfoils, which generate a high maximum lift, are not suitable for tailless aircraft because they have nose down pitching moment. Flat thin airfoils (Ashley H. and Landahl M. Aerodynamics of Wings and Bodies Dover Publications 1965 pgs 81-97), symmetrical airfoils (Eppler 168), or airfoils with a rear reflex (Eppler 184, Eppler 230) are required for tailless aircraft (Lennon, Andy, Basics of R/C Model Aircraft Design, Publisher Air Age Inc. 1996 ISBNO-911295-40-2). However these airfoils may have a lower maximum lift and a lower stall angle. Offsetting the stall angle can be facilitated by increasing the speed or decreasing the aspect ratio, which are both not suitable for an indoor or park-style slow flight toy aircraft. The present invention overcomes these drawbacks of the prior art.
SUMMARY OF THE INVENTION
In contrast to the prior art the aircraft of the present invention has the following unique features which combine to achieve the technologic objectives.
A lightweight slow flight lifting body is achieved with a high degree of flight stability, without tail or extended wings, using a series of opposing angled surfaces geometrically arranged around a central cavity (see FIGS.
1
-
4
). The lift surfaces are all angled from the horizontal to achieve large dihedral stability. Opposite angles of the lifting surface panels vectorally cancel out the lift vector directions to achieve high stability.
The lift surface area is high, for the narrow span and volume occupied. The central cavity encloses the power and control pod for air thrust channeling, safety, and crash resistance.
Using only one propeller, with no blade pitch control, and no control surfaces, controlled turning of the aircraft in a small radius at low speed can be achieved without significant induced banking or rolling. The thrust direction is regulated by rotating the motor and the prop thrust angle &bgr; within the cavity of the lifting body (see FIG.
3
).
The angle &agr; of the rotation plane for the prop is at an upward pitch to the horizontal (see FIG.
2
), providing an upward thrust vector and a balancing force. This maintains longitudinal stability because the center of gravity (CG) is forward of the aerodynamic center or neutral point of lift. The upward angle &agr; thrust vector counterbalances the nose down imbalance of the CG being forward of the aerodynamic center. The angle &agr; can be fixed or adjustable, preferably between 10 and 20 degrees. Increasing the power causes elevation of the flight path. Changing the angle &bgr; of the prop thrust vector (see
FIG. 3
) causes turning.
Compact Size, light weight and resiliency for a toy aircraft is achieved by using internal tension and compression bracing, and construction materials similar to that used for kites (see FIG.
5
). This design also generates a flat thin or thin symmetrical airfoil necessary for a tailless aircraft. Since this is a tailless aircraft, cambered airfoils are not preferred because they exhibit nose-down pitching moment which can't be counteracted by a tail-moment arm.
An aircraft constructed in accordance with the present invention exhibits the novel and unobvious combination of aerodynamic features se
Collins Timothy D.
Fay Sharpe Fagan Minnich & McKee LLP
Poon Peter M.
LandOfFree
Lightweight remotely controlled aircraft does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Lightweight remotely controlled aircraft, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lightweight remotely controlled aircraft will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3212588