Abstract:
The aircraft incorporates a single ducted propeller. The fuselage Bridges over the ducted propeller assembly, and is shaped in a way that the incoming air can smoothly flow into the propeller area. The duct has an aerodynamically shaped frontal area, and an aft extension, which forms the tail section. The wings are attached to the side of the duct. The ducted propeller assembly also contains louvers, which run span wise, to redirect the outgoing air in horizontal direction. During vertical take-off or landing, the propeller has a horizontal plane of rotation, after take-off the whole craft entirely tilts forward approximately 26 degrees to transition into horizontal wing born flight. During vertical flight, the aircraft is controlled by control louvers installed inside the ducted propeller assembly in the propeller slipstream.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The ultimate goal in designing a fixed wing VTOL aircraft is to be able to take off and land vertically and still have a smooth transition to a higher cruise speed and a relatively long range.  
           [0002]    It also needs to have a simple and effective way of controlling the aircraft during vertical take off or landing, and in transition to horizontal flight.  
           [0003]    My previous patent (U.S. Pat. No. 5,454,531 DUCTED PROPELLER AIRCRAFT) addresses the difficult challenge of vertical or short takeoff or landing in fixed wing aircraft with high-speed cruise, whit a multiple propeller configuration.  
           [0004]    With this present invention, I am simplifying the propulsion system by using only one propeller. With the single propeller this aircraft is more efficient, it is lighter, simpler, and safer. By tilting the whole aircraft forward to produce a horizontal thrust component, and using a single propulsion system, for vertical and horizontal flight, this invention eliminates a lot of mechanical complexity, and makes it an easy transition from vertical to horizontal flight, and vice versa.  
           [0005]    Many previous designs have included two separate power sources (one for vertical thrust and one for horizontal) (see U.S. Pat. Nos. 4,469,294; 3,083,935 and 3,388,878); ducted fans mounted in the fixed wings which rotate from horizontal to vertical (see U.S. Pat. No. 3,335,977); diverting jet engine exhaust turbo fans mounted above fixed wings and transitioning exhaust, through ducting from vertical to horizontal (see U.AS. Pat. No. 3,972,490) and the numerous tilt wings and tilt engine concepts configured from the late 1930&#39;s to today.  
           [0006]    All of these embodiments involve at least one of the three most troublesome aspects of VTOL aircraft designs. They may involve:  
           [0007]    1) Cumbersome, and therefore heavy, mechanisms for moving massive structures such as wings or ducted fan assemblies; or  
           [0008]    2) Sacrificing aerodynamic smoothness, thereby creating unacceptable drag; or  
           [0009]    3) Multiple power plants or complex drive trains, thus increasing weight and lowering performance.  
           [0010]    The goal of the present invention is to avoid all of these previously mentioned troublesome elements of S/VTOL designs while maintaining good performance during horizontal flight (high speed and long range) and efficient attitude control during hovering and transition flight, the ultimate intended configuration of all VTOL aircraft.  
         SUMMARY OF THE INVENTION  
         [0011]    The exemplary embodiment of this invention involves a fixed wing airborne vehicle capable of vertical take off and landing or short take off and landing (VTOL/STOL).  
           [0012]    Specifically, this invention relates to S/VTOL (short or vertical take off and landing) aircraft wherein a ducted propeller assembly is the sole source of thrust (which is powered by the engine) in vertical and horizontal flight. As used herein, the term aircraft includes any airborne vehicle.  
           [0013]    In the exemplary embodiment, the aircraft of the invention utilizes a single or twin engine mechanically driving a ducted propeller, mounted in a fixed position within the airframe.  
           [0014]    In vertical or short take off flight, roll, pitch, and yaw, are controlled by moveable louvers, and spoilers in the air stream of the ducted propeller propulsion.  
           [0015]    After vertical take off, the whole aircraft tilts gradually forward to approximately 26 degrees and accelerates to a conventional wing born flight.  
           [0016]    In the conventional configuration, roll, pitch, and yaw are controlled through conventional aerodynamic surface adjustments of ailerons, rudders, and elevator. The aircraft of this invention is also equipped with louvers positioned below the propeller. When the S/VTOL aircraft is tilted forward for horizontal flight, the thrust already has a significant horizontal component, but tilting or pivoting these louvers directs the thrust created by the propeller directed backward horizontally for high speed cruise. These louvers are designed to be flexible only in one direction, so when they reach the maximum tilting range, they are stopped by a stopping block, so they can be bent to the point where they form a nice arch for smooth airflow in a horizontal direction. Pressing the louvers against the stopping blocks will also prevent vibration or flutter.  
           [0017]    The entire aircraft of this invention is shaped in a way so that the airflow can smoothly enter the ducted propeller assembly during horizontal and vertical flight and also exit the duct smoothly. This is achieved by bridging the airfoil shaped fuselage over the ducted propeller assembly, and by shaping the frontal area of the duct and the aft extension as an airfoil in a way to assume a horizontal position in horizontal flight. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIG. 1 is a perspective view of an aircraft in accordance with the present invention.  
         [0019]    [0019]FIG. 2 is a side view showing the aircraft in taxi or short take-off position.  
         [0020]    [0020]FIG. 3 is a top plan view of the present invention.  
         [0021]    [0021]FIG. 4 is a side view with partial cutaway showing relative location and the inclination of the ducted propeller thrust/lift assembly during typical horizontal flight of the aircraft according to the invention.  
         [0022]    [0022]FIG. 5 is a side view with partial cutaway showing the fuselage and the ducted propeller thrust/lift assembly in reference to the ground during initial stages of vertical take off.  
         [0023]    [0023]FIG. 6 is a top view of the ducted propeller thrust/lift assembly showing the relative location of the engine, the drive shaft, the bevel drive gear, the propeller shaft, the propeller blades, the left and right wing attachment points, and the control surfaces for hovering and vertical flight, where the dotted lines indicate the vertical flight control surfaces&#39; movement.  
         [0024]    [0024]FIG. 7 is a cutaway cross sectional view of the fuselage at the point of bridging the ducted propeller assembly of the present invention taken of line  6 - 6  of FIG. 5.  
         [0025]    [0025]FIG. 8 is a cutaway cross sectional partial view of the fuselage along the longitudinal axis of the present invention taken of line  7 - 7  of FIG. 3.  
         [0026]    [0026]FIG. 9 is a cutaway cross sectional view of the present invention taken of line  6 - 6  of FIG. 5, and it shows the deployment of the spoiler for the roll control on the left side.  
         [0027]    [0027]FIG. 10 is a cutaway cross-section view of the present invention taken of line  6 - 6  of FIG. 5. It shows the deployment of the spoiler for the roll control on the right side.  
         [0028]    [0028]FIG. 11 is a cutaway cross sectional view of the present invention taken of line  7 - 7  of FIG. 3; it shows the deployment of the very front control louver (nose down pitch control for vertical flight).  
         [0029]    [0029]FIG. 12 is a cutaway cross sectional view of the present invention taken of line  7 - 7  FIG. 3, and it shows the deployment of the very aft control louver (nose up pitch control for vertical flight).  
         [0030]    [0030]FIG. 13 is a top view of the ducted propeller thrust/lift assembly showing the relative location of the engines, when the present invention is equipped with two engines. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0031]    Referring to the drawings, and particularly the FIGS. 1 through 5, the aircraft  10  of the invention is illustrated. As used herein the term aircraft is meant to include any airborne vehicle. In the preferred embodiment, the aircraft  10  takes the form of a single engine  90  turbo shaft, or rotary (Vankel type) powered aircraft incorporating the fuselage  16  which houses a tandem cockpit with canopy  18  and  19 . The fuselage  16  (and the cockpit) bridges over a ducted propeller assembly  20 . The fuselage  16 , or particularly the cockpit section, bridges directly over the axis of the propeller and tapers to a minimum cross-section to maximize air flow through the duct.  
         [0032]    The ducted propeller assembly  20  incorporates a forward lifting airfoil shaped surface  22  and extends through an aft extension, which forms the tail lifting surface  24  which mounts an elevator  25  and a pair of vertical tail surfaces which incorporates a pair of rudders  38 .  
         [0033]    Span wise the forward lifting surface  22  terminates in wing extensions  26  and  28 , which incorporates ailerons  34  and  36 . The wing  26  and  28  are detachable, for easy storage and transportation.  
         [0034]    As used herein the term propeller is intended to include any rotating blade mounted from a central hub  65  and operating at an angle of attack to the relative movement of air past the propeller. In the preferred embodiment, the propeller takes the form of a multi-bladed propeller. In this case the propeller hub  65  mounts five blades  46 . The propeller blades are fixed in flight, but the pitch is adjustable on the ground when the engine is not running. This aircraft can also be equipped whit an in flight variable pitch propeller.  
         [0035]    Referring to FIG. 7 and FIG. 8 the propeller hub  65  is mounted on the propeller shaft  64  which is supported by the upper bearing  66  and lower bearing  67 . The upper bearing  66  housing is mounted and supported by the longitudinal trailing edge of the fuselage  76  FIG. 8, and by the upper lateral spar  70  and  71 , FIG. 7. The lower bearing  67  housing is supported by the lower longitudinal spar  74  FIG. 8 and by the lower lateral spars  72  and  73  FIG. 7.  
         [0036]    Referring to FIG. 4, the aircraft is illustrated in horizontal flight. As used herein, the term aircraft related horizontal is intended to refer to horizontal line drawn through the aircraft in this flight mode.  
         [0037]    As will appear in FIG. 4 in the horizontal flight mode, the whole aircraft and therefore the ducted propeller assembly  20  are inclined forward at an angle to the incoming air stream.  
         [0038]    In the preferred embodiment, the angle for flight relative to aircraft-related and the propeller plane of rotation approximates 26 degrees. Therefore, the air exiting the ducted propeller assembly already has a substantial horizontal component due to the flight configuration of the aircraft itself.  
         [0039]    The exiting air is redirected to fully horizontal thrust by a series of louvers  23 , FIG. 4. The louvers  23  shown in phantom may be controlled to redirect the air exiting the fan in two principal modes, the vertical flight mode and the horizontal flight mode. In the horizontal flight mode, all of the louvers  23  redirect the air in the same direction (in this case, horizontally aft of the aircraft) resulting in substantial forward thrust.  
         [0040]    Louvers  23  are inter-connected by control rods  24  and  25 , FIG. 3 and FIG. 8. As they are moved simultaneously they tilt the louvers forward until they reach the stopping blocks  33  FIG. 8. As the leading edges of louvers  23  press against the stopping blocks  33  and as the control rods  24  and  25  are connected to the trailing edges of the louvers they can further bend these flexible louvers so they create a curved surface, therefore, the air an exit in more horizontal aft direction, and the bending force will prevent the louvers from flutter or vibration.  
         [0041]    The wing, in the horizontal flight mode, as will be most clearly appreciated from the end-on view of wing extension  26  on FIG. 4 operates at a small (wing air foil chord) positive angle of attack. FIG. 5 shows the operation of the aircraft in the vertical take off mode. During vertical touch down, the aircraft rests on the ground on a main landing gear  52  fully extended and the pair of tail wheels  30 . The fully extended main landing gear  52  keeps the propeller  46  or the ducted propeller assembly  20  in a horizontal position during vertical take off and landing.  
         [0042]    The main landing gear  52  can be selected in three positions:  
         [0043]    1) Fully extended for vertical landing or take-off FIG. 5.  
         [0044]    2) Partially extended for taxiing on the ground or for short take off FIG. 2 or in emergency in case of engine failure the aircraft can glide and land in a traditional manner on an airfield or on a sufficient flat surface with the main landing gear  52  selected in a partially extended position.  
         [0045]    3) Fully retracted for high-speed horizontal flight as on FIG. 4.  
         [0046]    After the engine  90  is started and the propeller rotates, thrust is produced. The louvers  23  are arranged so that the thrust has a substantially vertical component (see FIG. 5). This thrust results in the use of engine power to lift the aircraft vertically.  
         [0047]    The function of the louvers  23  in the vertical take off mode is to straighten the spiral motion of the downward moving air, created by the propeller  46 . Straightening the exiting air will enhance the vertical thrust. At the same time as the spiraling air hits the louvers  23  it tends to create an opposite force to the torque reaction of the propeller, which will help to keep the nose of the aircraft  10  straight.  
         [0048]    The conventional control surfaces used in horizontal flight are ineffectual during vertical take off and landing, when the horizontal speed is zero or close to zero. During vertical flight or hovering, the aircraft  10  is controlled by means of varying the center of the thrust of the propeller disc, via the very front  60  or aft  61  control louvers, or left  95  or right  96  spoilers (see FIG. 6). All flight control surfaces are controlled from the cockpit by moving he control stick  35  and ruder pedals  39 . The ailerons are connected to the bank control spoilers, the elevator is connected to the tilt control louvers, and the ruder is connected to the direction control louvers. Therefore the flight control surfaces which are controlling the aircraft in vertical flight mode, will be deployed simultaneously with the respective traditional wing born flight control surfaces, and vice versa.  
         [0049]    [0049]FIG. 7 illustrates the way airflows over the symmetrical airfoil shaped cross section of fuselage  16  and through the ducted propeller assembly  20 . The left  93  and the right  92  central louvers control the yaw, or direction, by moving them simultaneously in the opposite direction, respectively turning the nose of the aircraft  10  to the left or to the right. The deflection of these louvers creates a horizontal component of thrust around the central vertical axes of the aircraft  10 .  
         [0050]    The left  95  and the right  96  spoilers are mounted into the sidewalls of the ducted propeller assembly  20 , and below the propeller blades  46 . When the aircraft  10  needs to be tilted or rolled to the left during vertical flight mode (see FIG. 9), the left spoiler  95  is deployed by moving the control stick  35  in the cockpit (see FIG. 4 and  5 ) to the left which also simultaneously moves the left aileron  34  up and the right aileron  36  down (see FIG. 9).  
         [0051]    When the aircraft  10  needs to be tilted or rolled to the right during vertical flight mode, the right spoiler  96  is deployed by moving the control stick  35  to the right, and the right aileron  36  moves up and the left aileron  34  moves down (see FIG. 10) FIG. 8 illustrates a partial cross section of the side view of the ducted propeller assembly. Drive shaft  80  is connected to the engine shaft and coupled to the bevel gear  81  and propeller shaft  91 , which rotates the propeller  46 .  
         [0052]    When the aircraft  10  needs to be tilted or pitched forward during vertical flight, the front louver  60  is deployed by moving the control stick  35  forward, which simultaneously moves the elevator  25  down.  
         [0053]    The deployed louver  60  partially blocks the airflow thus reducing the thrust in the front area of the ducted propeller assembly, and subsequently shifting the center of thrust aft of the aircraft center of gravity. The resulting moment forces the aircraft to tilt forward (see FIG. 11) When the aircraft  10  needs to be tilted or rotated backward, during vertical flight the aft louver  61  is deployed by moving the control stick  35  in the cockpit aft, which simultaneously moves the elevator  25  up, creating a momentum along the aircraft longitudinal axis, and rotating the nose of the aircraft up, around the lateral axis (see FIG. 12). The throttle is active in vertical and horizontal flight modes to control the output of the engine  70 , therefore controlling the rate of climb or descent.  
         [0054]    If the aircraft  10  is equipped with two engines illustrated on FIG. 13, the left engine  99  having a drive shaft  101  is connected to the centrally located gear box  103 . The right engine  100  having a drive shaft  102  is connected from the right to the gearbox  103 , which is centrally located between the two engines  
         [0055]    The output shaft  80  runs centrally from the gearbox  103  to the bevel gear  81  and to the propeller shaft  91 , which rotates the propeller  46 .