Abstract:
An electric propulsion and lift system for an aircraft that includes a plurality of electric motor/propeller assemblies on the flaps of the aircraft so that when the flaps are deflected for take-off and landings, the propellers are directed downward to provide thrust for power lift and increased airflow over the wing for aerodynamic lift. The motor/propeller assemblies are spaced apart and positioned along the entire length of the flaps to provide a distributed airflow.

Description:
BACKGROUND 
       [0001]    Field 
         [0002]    This invention relates generally to a propulsion and lift system for an aircraft and, more particularly, to an electric propulsion and lift system for an aircraft, where the system includes a plurality of electric motor/propeller assemblies mounted to a flap at the trailing edge of the wings on the aircraft so that the motor and propeller deflect downward with the flap to provide both power lift and augmented aerodynamic lift. 
         [0003]    Discussion 
         [0004]    Aerodynamic lift is provided by an airfoil that has a particular curved shape so that air flows under the airfoil relatively straight and over the airfoil along a curve to provide higher pressure under the wing to provide the lift. For an aircraft the wings are the airfoil. Therefore, the aircraft wings must travel through the air at some speed depending on the weight and drag on the aircraft to provide suitable aerodynamic lift for fight. Usually, an aircraft wing will include flaps pivotally mounted to a trailing edge of the wing that are used to alter the airflow characteristics over the wing to increase the aerodynamic lift. More particularly, when the flaps are extended they increase the curvature of the wing which raises its lift coefficient, but increases the aircraft drag, so that the aircraft can be flown at slower speeds, which allows the aircraft to take off and land at lower speeds. 
         [0005]    There is a general desire in the aeronautics industry to reduce aircraft take-off and landing distances, while still maintaining an efficient cruise performance once the aircraft is in flight. One way of reducing and even eliminating take-off and landing distances is to provide power lift, where rotating blades typically provide downward thrust. For example, helicopters and other types of aircraft employ only power lift that allows the aircraft to take off and land vertically. However, providing only power lift requires a large amount of power depending on the aircraft payload, and thus increased cost, where the goal is typically to obtain the largest amount of lift capability with the lowest amount power. In order to provide cost/benefit advantages, it is known in the art to provide a combination of both aerodynamic lift and power lift to provide shorter take-off and landing distances, where the more power lift the aircraft has the higher the power requirements and the increased cost for the same payload. 
         [0006]    It is known in the art to not only provide a combination of power lift and aerodynamic lift for aircraft take-off and landing, but also to employ propellers for providing power lift and increased airflow over the wing to augment the aerodynamic lift. One known aircraft design that employs this type of combined power and aerodynamic lift for an aircraft is known as the Dornier DO-29 aircraft. The Dornier aircraft includes a tilting-propeller system that provides short take-off and landing distances, where the system includes pusher propellers on each wing to provide downward thrust and enhanced lift. However, the Dornier aircraft requires complicated mechanical connections to the pusher propellers, and does not provide distribution of the propeller thrust along the wing. 
       SUMMARY 
       [0007]    The present invention discloses and describes an electric propulsion and lift system for an aircraft that includes a plurality of electric motor/propeller assemblies mounted on the flaps of the aircraft so that when the flaps are extended for take-off and landings, the propellers are directed downward to provide thrust for power lift and increased airflow over the wing for augmented aerodynamic lift. The motor/propeller assemblies are spaced apart and positioned along the entire length of the flaps to provide a distributed airflow. 
         [0008]    Additional features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a top view of an aircraft having aircraft wings, where each wing includes a flap at its trailing edge and a plurality of electric motor/propeller assemblies spaced apart along the flaps; and 
           [0010]      FIG. 2  is a cross-sectional view through one of the wings of the aircraft showing the flap in an extended state. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0011]    The following discussion of the embodiments of the invention directed to an electric propulsion and lift system for an aircraft is merely exemplary in nature, and is in no way intended to limit the invention or its applications or uses. 
         [0012]      FIG. 1  is a top view of an aircraft  10  including a fuselage  12 , a right wing  14  mounted to a right side of the fuselage  12 , a left wing  16  mounted to a left side of the fuselage  12 , a horizontal stabilizer  18  and a vertical stabilizer  20 . A flap  22  is pivotally mounted to a trailing edge of the wing  14  and a flap  24  is pivotally mounted to a trailing edge of the wing  16 . Further, a cruise engine  30  including a propeller  32  is mounted to a leading edge  34  of the wing  14  and a cruise engine  36  including a propeller  38  is mounted to a leading edge  40  of the wing  16 . The aircraft  10  is intended to represent any aircraft suitable for an electric propulsion and lift system of the invention discussed herein, and can include single engine aircraft, multi-engine aircraft, prop aircraft, jet engine aircraft, swept-wing aircraft, straight-wing aircraft, commercial aircraft, military aircraft, etc. 
         [0013]    The electric propulsion and lift system of the invention on the aircraft  10  includes a plurality of electric motor/propeller assemblies  42  mounted to each of the flaps  22  and  24 , where each assembly  42  includes an electric motor  44  and a propeller  46  having propeller blades  48 . In this embodiment, four of the assemblies  42  are mounted to each of the flaps  22  and  24 . However, it is noted that this is for illustration purposes only in that the number of the assemblies  42  provided on the aircraft  10  would depend on various factors, such as the length of the flaps  22  and  24 , the size of the motors  44 , the size of the aircraft  10 , etc. 
         [0014]      FIG. 2  is a cross-sectional view through line  2 - 2  of the wing  16  showing the flap  24  in an extended orientation at a certain angle, where the assembly  42  is also angled downward. When the aircraft  10  is in its take-off or landing posture, the flaps  22  and  24  will be extended some amount depending on the aircraft type to provide additional aerodynamic lift as discussed above. When the flaps  22  and  24  are extended, and the propellers  46  are rotating, airflow is directed downward relative to the orientation of the aircraft  10  to provide some power lift. Further, rotation of the propellers  46  draws airflow over the wings  14  and  16  and the flaps  22  and  24  in addition to the airflow over the wings  14  and  6  caused by movement of the aircraft  10  to increase the aerodynamic lift, where the propellers  46  cause the direction of the flow to be more downward further increasing the lift capability. Traditionally, when the flaps  22  and  24  are extended, airflow over the wings  14  and  16  of the aircraft  10  is directed downward some amount which provides additional lift. However, if the deflection of the flaps  22  and  24  is greater than some amount, the airflow will not follow the corner where the flap  22  or  24  pivots relative to the wing  14  or  16 , creating airflow turbulence. By drawing air over the wings  14  and  16  using the propellers  46 , the amount that the flaps  22  and  26  can be extended before the airflow separates at the corner is increased, which provides increased aerodynamic lift in addition to the downward thrust provided by the propellers  46 . 
         [0015]    When the aircraft  10  takes off and has achieved a certain air speed, the flaps  22  and  24  are no longer needed for added lift, and they are retracted to provide a better in-flight cruise orientation. The engines  30  and  36  provide the main thrust that propels the aircraft  10  to provide airflow over the wings  14  and  16  for aerodynamic lift. When the aircraft  10  is in its cruise configuration and the flaps  22  and  24  are retracted, the electric motors  44  can be turned off because they are no longer needed to provide lift, and can be feathered or folded to reduce drag. In an alternate embodiment, the motors  40  can be left on, so that the propellers  46  provide additional thrust for aircraft cruising, which allows the size of the engines  30  and  36  to be reduced. In yet another embodiment, for certain aircraft designs it may be possible to eliminate the cruise engines  30  and  36 , where the electric motor/propeller assemblies  42  provide all of the lift and thrust capabilities for the aircraft  10 . 
         [0016]    For some designs, all of the motors  44  may be the same size. In other designs, the motors  44  can be of different sizes, where, for example, some of the motors  44  may only be run for aircraft flight during cruising operations, and where all of the motors  44  may be operational for take-off and landing. Further, because the motors  44  can be operated at different speeds, and thus provide different lift characteristics of the wings  14  and  16 , control of the motors  44  can be used to rotate the aircraft  10  for roll control, such as for turning, where it may be desirable to lift one of the wings  14  or  16  more than the other for landing or otherwise. Further, it may be desirable to provide a different number of the blades  48  on the propellers  46  for noise control or otherwise. 
         [0017]    As mentioned, the motors  44  are electric motors, which can be powered by any suitable power source, represented generally as power source  50 . In one non-limiting design, the power source  50  is a generator that is operated by rotation of the propellers  32  and  38  on the engines  30  and  36 . Alternately, the power source  50  can be one or more batteries, where the batteries  52  are charged by the engines  30  or  36  or externally charged when the aircraft  10  is on the ground. In yet another embodiment, it is possible to provide a separate battery in association with each of the motors  44 . 
         [0018]    The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.