Abstract:
System and method to construct vertical and/or short takeoff and landing (V/STOL) aerial vehicles capable of being folded into compact size, and capable of be combined with one or more such vehicles to form bigger composite aerial vehicles. Airframe of the vehicle comprises a plurality of wings on lateral or periphery of thrust generators, wherein arrangements of wings make it possible to optionally fold wings without moving thrust generators. Folding transforms such vehicles into ground vehicles which can share roads and house parking lots with conventional ground vehicles. Therefore such vehicles can be used as V/STOL flying cars. Means are provided for attaching to and detaching from one or more similarly equipped vehicles in flight or before takeoff, so that multiple vehicles can form a large composite vehicle. Compactness, combinability and V/STOL capability enable versatile applications.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     None. 
     FEDERALLY SPONSORED RESEARCH 
     None. 
     SEQUENCE LISTING 
     None. 
     TECHNICAL FIELD 
     This invention generally relates to manned aerial vehicle and unmanned aerial vehicle (UAV), and specifically provides system and method to construct vertical and/or short takeoff and landing (V/STOL) aerial vehicles capable of being folded into compact size, and capable of be combined with one or more such vehicles to form bigger composite aerial vehicles. 
     BACKGROUND 
     Previously, some exemplary V/STOL aircrafts are: CH-47 Chinook helicopter ( FIG. 1 ) with counter-rotating twin-rotor, V-22 Osprey ( FIG. 2 ) with wing-tip mounted counter-rotating twin-rotor and AV-8B Harrier II featuring a single turbofan engine with two intakes and four thrust-vectoring nozzles. Helicopter in general has a long history and is improved overtime, and now it&#39;s near its limits. One disadvantage of helicopter is that its horizontal speed is limited comparing to conventional fixed wing aircraft. The wing spans of V-22 Osprey type of V/STOL aircrafts are usually limited due to the fact that as the wing span becomes longer, it becomes harder to maintain enough mechanic structure strength to support wing tip mounted heavy rotors without adding a lot of weight penalty. Limited wing span limits lift generated by the wing in horizontal flight, and results in lower efficiency in horizontal flight. AV-8B Harrier II type of V/STOL aircrafts uses jet engine. One of objectives of the present invention is to be able to use wide range of power plants including electric engine, internal combustion engine and jet engine. 
     Wings are usually main parts of an airframe. A pair of swept wings generally results in V-shape. There are 2 types of swept wings: swept-back wing and forward-swept wing. Swept wings, especially swept-back wings, are widely used in modern aircrafts with high horizontal flight speed. Swept and un-swept wings generally provide lift, store fuel and hold aerodynamic controls such as flap, aileron and elevator. A special type of wing, Chaplin V-Wing ( FIG. 3A to 3E ) with boundary-layer-controlled thick-suction airfoil can also hold cargo and passengers. Chaplin V-Wing aircraft is envisioned for horizontal takeoff and landing. Its engines are mounted right after head of the V-shape. While all the above mentioned functions of wings can still applied to the wings used in the present invention, the present invention primarily utilizes the space enclosed by swept wings to dispose thrust-generating devices such as propellers, ducted fan and jet nozzles. Beside V-shape, the present invention also utilizes other shapes such as X-shape. When multiple vehicles are combined or connected together to form a larger composite aircraft, the number of resulted shapes is almost endless. 
     BRIEF SUMMARY 
     In accordance with the exemplary embodiments thereof described herein, the present invention provides a system and method to construct compact and combinable V/STOL aerial vehicle with thrust-generating devices disposed in space enclosed by swept wings. The vehicle utilizes one or more power plants. When more than one power plants are utilized, they can be of the same type, and can also be of different types (i.e., hybrid engines), and furthermore they can have different output power capacities. Thrust vectors can change directions of the vectors in 2 dimensions (2D) or 3 dimensions (3D). The coupling of a power plant with one or more thrust-generating devices can be indirectly via transmission devices or directly. 
     In accordance with the exemplary embodiments, the wings of a vehicle can be folded, and therefore the vehicle can have compact size so that it can be parked at parking lot in front of an ordinary house, and can be driven independently, or towed by or carried on a ground vehicle on highway while satisfying legal dimensional limits. In military application, such a UAV can be carried on roof of personnel carrier ground vehicle or towed by a ground vehicle to travel together with Army soldiers for providing instant air support, surveying or ground attack. In civilian application, such a manned vehicle becomes a flying car with driver as its pilot and one or more passengers. It&#39;s capable of taking off and landing vertically in parking lot. 
     In accordance with the exemplary embodiments, for special applications, multiple vehicles can be combined together to form a larger composite aircraft. They can be assembled on the ground and then take off together, or they can take off individually, rendezvous and connect to each other in the air. 
     The following detailed description and accompanying drawings are provided for purposes of illustrating and describing presently preferred embodiments of the invention and are not intended to limit the scope of the invention in any way. It will be recognized that further embodiments of the invention may be used. 
     While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an upper left front perspective view of CH-47 Chinook helicopter with counter-rotating twin-rotor. 
         FIG. 2  is an upper right front perspective view of V-22 Osprey with wing-tip mounted counter-rotating twin-rotor. 
         FIG. 3A  is a side view of Chaplin V-Wing. 
         FIG. 3B  is a plan view of Chaplin V-Wing. 
         FIG. 3C  is an upper left front perspective view of Chaplin V-Wing. 
         FIG. 3D  is a steam-wise cross section view of A-A cross section in  FIG. 3B . 
         FIG. 3E  is a cross section view of B-B cross section in  FIG. 3B . 
         FIG. 4  illustrates Goldschmied airfoil. 
         FIG. 5  is a diagram of major components of onboard avionics and flight control system. 
         FIG. 6A  illustrates approaching phase of in-flight rendezvous and docking system in lateral mode. 
         FIG. 6B  illustrates approaching phase of in-flight rendezvous and docking system in longitudinal mode. 
         FIG. 6C  illustrates lined up phase of in-flight rendezvous and docking system in lateral mode. 
         FIGS. 7A and 7B  are upper left front perspective view of the 1 st  embodiment in horizontal flight configuration and VTOL configuration respectively. 
         FIG. 7C  is a weight and thrust vector diagram with 3D thrust vectoring and 2 thrust generators. 
         FIG. 7D  is a weight and thrust vector diagram with 3D thrust vectoring and 3 thrust generators. 
         FIG. 7E  is a weight and thrust vector diagram with 2D thrust vectoring and 3 thrust generators. 
         FIGS. 8A and 8B  are upper left front perspective view of an alternative of the 1 St  embodiment in horizontal flight configuration and VTOL configuration respectively. 
         FIGS. 9A and 9B  are upper left front perspective view of the 2 nd  embodiment in horizontal flight configuration and VTOL configuration respectively. 
         FIGS. 10A and 10B  are upper left front perspective view of an alternative of the 2 nd  embodiment in horizontal flight configuration and VTOL configuration respectively. 
         FIGS. 11A ,  11 B and  11 C are upper left front perspective view of the 3 rd  embodiment in horizontal flight configuration, VTOL configuration and folded ground vehicle configuration respectively. 
         FIGS. 12A ,  12 B and  12 C are upper left front perspective view of alternative 1 of the 3 rd  embodiment in horizontal flight configuration, VTOL configuration and folded ground vehicle configuration respectively. 
         FIG. 13  is an upper left front perspective view of alternative 2 of the 3 rd  embodiment in horizontal flight configuration. 
         FIGS. 14A ,  14 B and  14 C are upper left front perspective view of alternative 3 of the 3 rd  embodiment in folded ground vehicle configuration, horizontal flight configuration and VTOL configuration respectively. 
         FIGS. 15A ,  15 B and  15 C are upper left front perspective view of alternative 4 of the 3 rd  embodiment in horizontal flight configuration, VTOL configuration and folded ground vehicle configuration respectively. 
         FIGS. 16A ,  16 B and  16 C are upper left front perspective view of the 4 th  embodiment in folded ground vehicle configuration, horizontal flight configuration and VTOL configuration respectively. 
         FIGS. 16D and 16E  are front view of the 4 th  embodiment with vertical stabilizer in winglet configuration and in upright vertical position respectively. 
         FIG. 17  is an upper left front perspective view of alternative 1 of the 4 th . Fuselage of this alternative embodiment is in shape of Goldschmied airfoil. 
         FIG. 18  is an upper left front perspective view of alternative 2 of the 4 th . Thrust generators of this alternative embodiment are of a particular form: ducted fan. 
         FIG. 19A  is an upper left front perspective view of alternative 3 of the 4 th . Fuselage of this alternative embodiment is slimmer in order to reduce drag. It&#39;s intended for unmanned applications. 
         FIGS. 19B and 19C  are upper left front perspective view and top view of a particular form of powertrain respectively. 
         FIG. 20A to 20K  are top views of various formation configurations. 
     
    
    
     DETAILED DESCRIPTION 
     FIGS.  7 A to  7 C—First Embodiment 
     The first embodiment is illustrated in  FIG. 7A  (perspective view of horizontal flight configuration) and  FIG. 7B  (perspective view of VTOL configuration with landing gears extended). Left wing  1010  and right wing  1012  are joined at head position to form a general V shape. Front thrust generator  1020  and rear thrust generator  1022  are supported by front beam  1030  and rear beam  1032 . Although thrust generators in  FIG. 7A  are shown in form of propeller driven by an engine, other forms of thrust generators such as jet, turbofan can also be used. In such pictures, thrust generators have to be shown in a form, and here the propeller form is chosen, so it should not be interpreted that only propeller form can be used. 
     Optionally, there are pivotable control surface  1040  and  1044  at trailing edge of left wing  1010 , and symmetrically with respect to rolling axis,  1042  and  1046  are located at trailing edge of right wing  1012 . Control surface  1040  and  1042  function as traditional flaps for increased lift, and they can also function as part of ailerons. A control surface that combines an aileron and flap is called a flaperon. Control surface  1044  and  1046  are located behind center of gravity (CG), and function as both traditional ailerons to control rolling rotation about longitudinal axis or rolling axis, and traditional elevators to control pitching rotation about lateral axis or pitching axis. 
     When pivotable control surface  1040 / 1042  or  1044 / 1046  are not implemented, corresponding functions can be performed by thrust generator via equations (10) through (8) below. With pivotable control surface  1040 / 1042  and  1044 / 1046  are implemented, control handling is enhanced and more flexible. 
     Front landing gear  1050  locates under head section where right and left wing are joined together. Left landing gear  1052  and right landing gear are located under rear half segments of left and right wing respectively. In a vertical plane parallel to longitudinal axis, these 3 landing gears rotate back and forth to extending and retracting position respectively. 
     OPERATION 
     FIGS.  7 A to  7 C—First Embodiment 
     In horizontal takeoff, landing and flight mode, configuration of the first embodiment is shown in  FIG. 7A . Thrust generators  1020  and  1022  are generally facing forward. In these modes, the first embodiment operates in the same way as a conventional airplane. 
     In vertical takeoff mode, configuration of the first embodiment is shown in  FIG. 7B . Thrust generators  1020  and  1022  are generally facing upward. In General, during vertical takeoff, throttles of thrust generators are increased and independently controlled, and directions of thrust are also independently controlled so that total generated thrust is greater than weight of the vehicle in order to lift up the vehicle, and total moment with regarding its CG is zero or always approaching zero when it&#39;s disturbed in order to eliminate or minimize rotations. When the vehicle starts to move up, it&#39;s no longer necessary to increase throttles. In details, control of translation movement along and rotation movement about longitudinal, lateral and perpendicular axis are described below. 
       FIG. 7C  is a weight and thrust vector diagram of the first embodiment and it also applies to thrust configuration of all embodiments configured with 2 thrust generators in this inventions. CG is chosen as the point of origin O of the coordinate system. In  FIG. 7C , thrust vector T 1  generated by thrust generator  1020  and T 2  generated by thrust generator  1022  are shown to be decomposed into 3 orthogonal components (T 1R , T 1P , T 1Y ) and (T 2R , T 2P , T 2Y ) respectively. Throttles of thrust generator  1020  and  1022  control magnitude of thrust vector T 1  and T 2  respectively. The orientation angle of thrust generator  1020  and  1022  controls how thrust vector T 1  and T 2  are decomposed into 3 orthogonal components (T 1R , T 1P , T 1Y ) and (T 2R , T 2P , T 2Y ) respectively. 
     During vertical takeoff, translational motion along yawing axis (OY axis shown in  FIG. 7C ) is controlled by thrust vector component T 1Y  and T 2Y . When sum of T 1Y  and T 2Y  is greater than vehicle weight W, the vehicle will accelerate in OY axis direction, and therefore will be lifted up. When there is sufficient upward velocity, sum of T 1Y  and T 2Y  can also be adjusted to be equal to W. 
     During vertical takeoff, translational motion along rolling axis (OR axis shown in  FIG. 7C ) is controlled by thrust vector component T 1R  and T 2R . To achieve zero translational motion along rolling axis, change T 1R  or T 2R  or both in opposite direction of the motion. 
     Similarly during vertical takeoff, translational motion along pitching axis (OP axis shown in  FIG. 2C ) is controlled by thrust vector component T 1P  and T 2P . To achieve zero translational motion along pitching axis, change T 1P  or T 2P  or both in opposite direction of the motion. 
     During vertical takeoff, rotational motions around rolling axis OR, pitching axis OP and yawing axis OY are controlled by net moment of thrust vectors. Moment vector M k  of thrust vector T k  is cross product of vector OG k  and thrust vector T k , i.e.,
 
 M   k   =OG   k   ×T   k   (1)
 
where k=1 and 2 in the case of 2 thrust generators (or k=1, 2 and 3 in the case of 3 thrust generators); G k  is the position of thrust generator with coordinates (r k , p k , y k ), and vector OG k  is the vector from origin O to pint G k .
 
     Components of moment vector M k  in rolling, pitching and yawing axis are denoted as rolling moment M kR , pitching moment M kP  and yawing moment M kY  respectively, and from the above vector cross product equation (1), we have:
 
 M   kR   =p   k   T   kY   −y   k   T   kP   (2)
 
 M   kP   =y   k   T   kR   −r   k   T   kY   (3)
 
 M   kY   =r   k   T   kP   −p   k   T   kR   (4)
 
where k=1 and 2.
 
     Net moment vector M is sum of all moment vector M k , i.e.,
 
M=ΣM k   (5)
 
     Corresponding net rolling moment M R , net pitching moment M P  and net yawing moment M Y  are:
 
 M   R =Σ( p   k   T   kY   −y   k   T   kP )  (6)
 
 M   P =Σ( y   k   T   kR   −r   k   T   kY )  (7)
 
 M   Y =Σ( r   k   T   kP   −p   k   T   kR )  (8)
 
where k=1 and 2 (or k=1, 2 and 3 in the case of 3 thrust generators).
 
     During vertical takeoff, when there are rotational motions due to disturbance, net moment component M R , M P  and M Y  can be adjusted by changing T kR , T kP  and T kY  (where k=1 and 2) according to the above formulae so that the net moment vector M causes the vehicle to return its original state with zero rolling, pitching and yawing angle. 
     In vertical landing mode, the vehicle operates in the same way as in vertical takeoff mode, except sum of T 1Y  and T 2Y  is adjusted to be less than vehicle weight W when there is no downward movement, or to be equal to W when there is sufficient downward velocity. 
     In hover mode, the vehicle operates in the same way as in vertical takeoff and landing mode, except 1) when there is upward speed, goes to vertical landing mode; 2) when there is downward speed, goes to vertical takeoff mode; and 3) when there is no vertical speed, adjust sum of thrust component T 1Y  and T 2Y  to be equal to vehicle weight W. 
     When transiting from vertical takeoff mode to horizontal flight mode, thrust vector T 1  and T 2  are gradually rotated toward its horizontal flight position, which is approximately parallel to OR axis. The vehicle will gradually build up forward speed, and wings will start to generate lift. When the forward speed is fast enough so that lift generated by wings is no less than vehicle weight W, the transition is completed. 
     When transiting from horizontal flight mode to hover or vertical landing mode, thrust vector T 1  and T 2  are gradually rotated to pass direction of OY axis so that there are thrust components in the opposite direction of horizontal movement in order to reduce horizontal movement speed towards zero. When horizontal movement speed comes down to zero, the transition is completed. When zero horizontal is not strictly required, it&#39;s good to have some horizontal speed during descending. 
     DETAILED DESCRIPTION 
     FIGS.  8 A to  8 B—Alternative of First Embodiment 
     An alternative embodiment of the first embodiment is illustrated in  FIG. 8A  (perspective view of normal horizontal flight configuration) and  FIG. 8B  (perspective view of VTOL configuration with landing gears extended). The structure of the alternative embodiment is the same as that of the first embodiment, except there are 3 thrust generators. Front thrust generator  1020  is disposed at the middle of front beam  1030 . Rear thrust generator  1022  is disposed on rear beam  1032  on left side of rolling axis (OR axis in  FIG. 7D ) passing through CG of the embodiment. Rear thrust generator  1024  is disposed on rear beam  1032  on right side of rolling axis. As shown in  FIGS. 7D and 7E , G 1 , G 2  and G 3  are centers of thrust generator  1020 ,  1024  and  1022  respectively, and their coordinates are (r 1 , p 1 , y 1 ), (r 2 , p 2 , y 2 ) and (r 3 , p 3 , y 3 ) respectively. Plane passing through G 1 , G 2  and G 3  is generally parallel to rolling axis OR and pitching axis OP. 
     Preferred CG position is a position which satisfies the following 2 conditions: 
     1. G 1 , G 2  and G 3  are on the plane passing through rolling axis OR and pitching axis OP.
         This condition can also be expressed as: y k =0 (where K=1, 2, and 3).       

     2. G1 is on rolling axis OR. This condition can also be expressed as: p 1 =0. 
     In real operations, CG position will often change due to various reasons such as dropping payload, consuming fuel, etc. 
     OPERATION 
     FIGS.  8 A to  8 B—Alternative of First Embodiment 
     The operation of the alternative embodiment of the first embodiment is the same as that of the first embodiment except vertical takeoff and landing is possible with only 2D thrust vectoring. 
     When 3D thrust vectoring is used as shown in  FIG. 7D , formulae to calculate net rolling moment M R , net pitching moment M P  and net yawing moment M Y  are the same as equation (6), (7) and (8) except the subscript K=1, 2, and 3. 
     When 2D thrust vectoring is applied as shown in  FIG. 7E , there is no side thrust vectoring, so side thrust component T kP =0 (where K=1, 2, and 3), and therefore for 2D thrust vectoring, equation (6), (7) and (8) are reduced into the following form:
 
 M   R =Σ( p   k   T   kY )  (9)
 
 M   P =Σ( y   k   T   kR   −r   k   T   kY )  (10)
 
 M   Y =Σ(− p   k   T   kR )  (11)
 
where k=1, 2 and 3.
 
     For the case where CG is at the preferred position, we have p i =0 and y k =0 (where K=1, 2, and 3), and therefore equation (9), (10) and (11) are further simplified to:
 
 M   R   =p   2   T   2Y   +p   3   T   3Y   (12)
 
 M   P   =−r   1   T   1Y −( r   2   T   2Y   +r   3   T   3Y )  (13)
 
 M   Y   =−p   2   T   2R   −p   3   T   3R   (14)
 
     Thus for the case where CG is at the preferred position, rolling and yawing rotations are only controlled by 2 rear thrust generators. Also M Y  is decoupled from M R  and M P . When M R  needs be changed to roll the vehicle back to zero rolling angle (i.e., wings are leveled), although T 2Y  and T 3Y  need be changed, T 1Y  can be adjusted so that there is no change in pitching moment M P . When M P  need be changed to control pitching rotation, adjusting only T 1Y  would not affect rolling moment M R . Therefore there are ways to adjusting anyone of moment component M Y , M R  and M P  without affecting any other moment components. 
     Configuration of 3 thrust generators is preferred over that of 2 thrust generators for the following reasons:
         1. 2D thrust vectoring is sufficient for VTOL in the configuration of 3 thrust generators.   2. 2D thrust vectoring is simpler than 3D thrust vectoring.   3. Due to less coupling, it&#39;s much easier to adjust throttles and vectoring angles to achieve desired rotational motion control.       

     DETAILED DESCRIPTION 
     FIG.  5 —Avionics and Flight Control System of all Embodiments 
     Major components of avionics and flight control system of all embodiments in this invention are illustrated in  FIG. 5 . The coordinate system ORPY in  FIG. 5  is the same as that in  FIG. 7C to 7E . 
     Three GPS receiver  801 ,  802  and  803  form a differential GPS measuring sub-system, which can measure positions of 2 GPS receivers (e.g.,  802  and  803 ) relative to a common base GPS receiver (e.g.,  801 ) in high accuracy due to error cancellation in the differential mode. Attitude of an aircraft can be determined by 3 angles: rolling angle around OR axis, pitching angle around OP axis, and yawing angle around OY axis. With the relative positions measured, attitude of an aircraft can be calculated. For example, assume receiver  801 ,  802  and  803  form an equilateral triangle, and length of an edge is 100 cm. Height of the triangle is 100 cm*sin 60=86.6 cm. When a measurement indicates that both receiver  802  and  803  are 10 cm lower than base receiver  801  in Y direction, pitching angle of the aircraft can be calculated as sin −1 (10/86.6)=6.6 degrees, i.e., the aircraft pitched up 6.6 degrees. 
     Translational motion parameters, such as position and velocity, can be read out from any of these 3 GPS receivers. Their accuracy is within normal GPS error range. 
     In order to continue to work in the case GPS signal is lost or is too noisy, the differential GPS measuring sub-system is augmented with traditional inertia sensors.  812  is a 3D accelerometer to measure 3D accelerations. Integral of acceleration over time yields velocity, and integral of velocity over time results in position.  813  is a 3D gyroscope sensor to measure 3D rotation speed. Integral of rotation speed over time yields rotation angle.  814  is 3D magnetic sensor which can be used to determine orientation by measure 3D components of Earth magnetic field. 
     The sensor system is further augmented by 3 pairs of infrared sensors. A commercial product claims to offer accuracy to 1 degree of the horizon by sensing the temperature variation between the earth and the sky. Pair of infrared sensor  804  and  805 , pair of  806  and  807  and pair of  808  and  809  are disposed along rolling, pitching and yawing axis respectively. Each infrared sensor is facing outward. Under normal circumstance, infrared sensors can provide 2 of 3 attitude angels: rolling and pitching angle. Yawing angle can be provided by 3D magnetic sensor  814 . Pair of  808  and  809  provides reference temperature of earth and sky respectively, and helps to determine if aircraft is upside down. Pair of  804  and  805  senses pitch angle. Pair of  806  and  807  senses roll or bank angle. 
     Differential air pressure sensor  810  measures air speed. Absolute air pressure sensor  811  measures altitude by sensing atmospheric pressure.  815  is an optional radar for collision avoidance. And  816  and  817  is an optional pair of image sensor for stereo vision. 
     All the above sensor data are fed in real time into data acquisition sub-system  830 , which preprocessed the data, and then feed the preprocessed data to a faster core data processing sub-system  831 . Core data processing sub-system  831  performs CPU intensive computation to calculate values of vital parameters, such as 6 degree of freedom (6DOF) parameters (3D position plus 3D attitude), velocity, acceleration, etc. in real time. These real time vital parameter values are passed to autopilot sub-system  832 . With information of next waypoint, current 6DOF, velocity and acceleration, etc., autopilot sub-system determines next desired 6DOF, velocity and acceleration, etc., and issues commands to various actuators (1 st  actuator  8033 , 2 nd  actuator  8034 , 3 rd  actuator  8035 , . . . , last actuator  8036 ) to control various flight controls such as engine throttle, thrust vectoring, ailerons, flaps, elevators in order to reach desired flight state. 
     Autopilot sub-system  832  also communicates with communication system  837  and payload control system  838 . Payload control system  838  also communicates with communication system  837 . For example, video camera payload sends images to and receives commands from ground control station via communication system  837 . 
     DETAILED DESCRIPTION 
     FIGS.  9 A to  9 B—Second Embodiment 
     The 2nd embodiment is illustrated in  FIG. 9A  (perspective view of normal horizontal flight configuration) and  FIG. 9B  (perspective view of VTOL configuration with landing gears extended). It&#39;s derived from the embodiment illustrated in  FIGS. 8A and 8B . The structural changes are:
         1. Rear beam  2032  is horizontally connected to the rear ends of left wing  2010  and right wing  2012 .   2. Left vertical stabilizer  2014  and right vertical stabilizer  2016  are vertically connected to rear ends of left wing  2010  and right wing  2012  respectively, and also function as winglet of left wing  2010  and right wing  2012  respectively. Pivotable rudder  2046  and  2048  are disposed at trailing edges of left vertical stabilizer  2014  and right vertical stabilizer  2016  respectively.   3. Horizontal stabilizer  2018  is disposed between left vertical stabilizer  2014  and right vertical stabilizer  2016 . It&#39;s connected to higher ends of the left and right vertical stabilizer. Pivotable elevator  2040  is disposed at middle section of trailing edge of horizontal stabilizer  2018 . Pivotable left aileron  2042  and right aileron  2044  are disposed at left and right section of trailing edge of horizontal stabilizer  2018  respectively.   4. Left downward winglet  2019  and right downward winglet  2017  (obstructed in  FIGS. 9A and 9B ) are disposed below left vertical stabilizer  2014  and right vertical stabilizer  2016  respectively, and are connected to rear ends of left wing  2010  and right wing  2012  respectively.       

     OPERATION 
     FIGS.  9 A to  9 B—Second Embodiment 
     In horizontal takeoff, landing and flight mode, configuration of the 2nd embodiment is shown in  FIG. 9A . Thrust generators  2020 ,  2022  and  2024  are generally facing forward. In these modes, the 2nd embodiment operates in the same way as a conventional airplane. 
     In all other modes, i.e. in vertical takeoff mode, vertical landing mode, hover mode, mode of transition from vertical takeoff to horizontal flight, and mode of transition from horizontal flight to vertical landing, the 2nd embodiment operates in the same way as the embodiment in  FIGS. 8A and 8B . 
     DETAILED DESCRIPTION 
     FIGS.  10 A to  10 B—Alternative of Second Embodiment 
     An alternative of the second embodiment is illustrated in  FIG. 10A  (perspective view of normal horizontal flight configuration) and  FIG. 10B  (perspective view of VTOL configuration with landing gears extended). Comparing to the second embodiment, the structural differences are:
         1. In the alternative embodiment, 2 rear thrust generators and rear beam are moved forward to give room to horizontal stabilizer.   2. In the alternative embodiment, horizontal stabilizer is disposed between rear ends of left and right wing, and is connected to rear ends of left and right wing.   3. In the alternative embodiment, a fuselage is disposed between front and rear beam, and connected to the middle sections of front and rear beam.       

     OPERATION 
     FIGS.  10 A to  10 B—Alternative of Second Embodiment 
     The alternative embodiment illustrated in  FIGS. 10A and 10B  operates in the same way as the second embodiment illustrated in  FIGS. 9A and 9B . 
     DETAILED DESCRIPTION 
     FIGS.  11 A to  11 C—Third Embodiment 
     The third embodiment is illustrated in  FIG. 11A  (perspective view of normal horizontal flight configuration),  FIG. 11B  (perspective view of VTOL configuration with landing gears extended) and  FIG. 11C  (perspective view of ground vehicle configuration with wings folded). It&#39;s derived from the embodiment illustrated in  FIGS. 10A and 10B . Comparing to the embodiment illustrated in  FIGS. 10A and 10B , the structural changes are:
         1. In order to give room so that front thrust generator  3020  can be moved forward, the cord lengths of 2 wing segments which are closer to center rolling axis are reduced, and therefore these 2 wing segments become another set of wings. Now roots of left minor wing  3011  and right minor wing  3013  joint together at the head of vehicle. Roots of left major wing  3010  and right major wing  3012  are connected to tips of left minor wing  3011  and right minor wing  3013  respectively.   2. Front fuselage  3060  is disposed at roots of left minor wing  3011  and right minor wing  3013 . There are 2 new side fuselages. Front ends of left side fuselage  3062  and right side fuselage  3064  connect to roots of left major wing  3010  and right major wing  3012  respectively. The side fuselages run parallel to rolling axis. Rear ends of left side fuselage  3062  and right side fuselage  3064  connect to horizontal stabilizer  3018 .   3. Instead of connections to wings, front beam  3030  and rear beam  3032  now connect to the side fuselages.   4. Front landing gear  3050 , left rear landing gear  3052  and right rear landing gear  3054  are disposed at rear segments and front fuselage  3060 , left side fuselage  3062  and right side fuselage  3064  respectively. They rotate back and forth around axes parallel to pitching axis to extended and retracted positions.   5. Docking probe  3070  is mounted to head of the vehicle, and corresponding drogues are embedded in  2  ends of horizontal stabilizer. Please refer to section of embodiments of formation for more details.       

     OPERATION 
     FIGS.  11 A to  11 C—Third Embodiment 
     There is a new operation mode: ground vehicle mode. In ground vehicle mode, left major wing  3010 , right major wing  3012 , left vertical stabilizer  3016  and right vertical stabilizer  3014 , left lower wing tip  3019  and right lower wing tip  3017  (obstructed in  FIGS. 11A and 11B ), left and right segment of horizontal stabilizer  3018  are folded up by rotating around the side fuselages. Front landing gear  3050  acts as steering wheel to turn the vehicle. To move forward, thrust generators are generally facing forward. To move backward, thrust generators are generally facing upward and tilted backward. 
     In all other modes, the third embodiment operates in the same way as the embodiment in  FIGS. 10A and 10B . 
     DETAILED DESCRIPTION 
     FIGS.  12 A to  12 C—Alternative 1 of Third Embodiment 
     An alternative of the third embodiment is illustrated in  FIG. 12A  (perspective view of normal horizontal flight configuration),  FIG. 12B  (perspective view of VTOL configuration with landing gears extended) and  FIG. 12C  (perspective view of ground vehicle configuration with wings folded). Comparing to the third embodiment, the structural differences are:
         1. Front minor wings are swept further backward, and moved further forward so that front thrust generator is able to be moved further forward. Leading edge of a front minor wing is not in the same line of leading edge of a major wing on the same side.   2. Front fuselage extended backward to where front thrust generator is.   3. Length of horizontal stabilizer is shortened so that it does not extend beyond rear end of side fuselages.   4. Rear thrust generators are moved backward and disposed on the horizontal stabilizer. Since now rear thrust generators are supported by horizontal stabilizer, there is no rear beam.       

     OPERATION 
     FIGS.  12 A to  12 C—Alternative 1 of Third Embodiment 
     The alternative embodiment illustrated in  FIGS. 12A ,  12 B and  12 C operates in the same way as the third embodiment illustrated in  FIGS. 11A ,  11 B and  11 C. 
     DETAILED DESCRIPTION 
     FIG.  13 —Alternative 2 of Third Embodiment 
     An alternative of the third embodiment is illustrated in  FIG. 13 . It has the same structure as alternative 1 (shown in  FIG. 12A to 12C ) of the third embodiment, except major wings are also further swept back so that the leading edges of front minor wings are in the same line of leading edges of corresponding major wings. 
     OPERATION 
     FIG.  13 —Alternative 2 of Third Embodiment 
     The alternative embodiment illustrated in  FIG. 13  operates in the same way as the third embodiment illustrated in  FIGS. 11A ,  11 B and  11 C. 
     DETAILED DESCRIPTION 
     FIGS.  14 A to  14 C—Alternative 3 of Third Embodiment 
     An alternative of the third embodiment is illustrated in  FIG. 14B  (perspective view of normal horizontal flight configuration),  FIG. 14C  (perspective view of VTOL configuration with landing gears extended) and  FIG. 14A  (perspective view of ground vehicle configuration with wings folded). It has the same structure as alternative 1 (shown in  FIG. 12A to 12C ) of the third embodiment, except the following changes:
         1. Side fuselage are extended forward so that they are between and connected to tips of corresponding minor wings and roots of corresponding major wings.   2. Major wings are widened and extended backward so that rear ends of roots of major wings are approximately connected to corresponding rear ends of side fuselages.   3. When side fuselages also take shape of root of major wing, a side fuselage and a major wing on the same side looks like one wing in the horizontal flight configuration.       

     OPERATION 
     FIGS.  14 A to  14 C—Alternative 3 of Third Embodiment 
     Alternative 3 illustrated in  FIGS. 14B ,  14 C and  14 A operates in the same way as the alternative 2 illustrated in  FIG. 13 . 
     DETAILED DESCRIPTION 
     FIGS.  15 A to  15 C—Alternative 4 of Third Embodiment 
     An alternative of the third embodiment is illustrated in  FIG. 15A  (perspective view of normal horizontal flight configuration),  FIG. 15B  (perspective view of VTOL configuration with landing gears extended) and  FIG. 15C  (perspective view of ground vehicle configuration with wings folded). It&#39;s a specialized form of alternative embodiment 3 (shown in  FIG. 14A to 14C ) of the third embodiment. It has the same structure as alternative embodiment 3, except the following changes:
         1. Thrust generators are now in specialized form: jet nozzles.   2. Front fuselage is extended all the way back to horizontal stabilizer, and becomes center fuselage. At the front, there are 2 side air inlets of one or more jet engines, which generate air jet stream, which is further split into 3 air jet streams: center one and 2 side ones. Two side air jet streams are routed to 2 rear side nozzles by pipes. In VTOL mode, side air jet streams exit from side nozzles pointing in general downward direction, and center air jet stream goes to front center nozzle, which is disposed in the middle section of center fuselage, and ejects air from the nozzle downward to produce lift. In horizontal flight mode, front center nozzle is rotated to face backward and allow center air jet stream to go to rear center nozzle, which is facing backward, and side nozzles can be shut off.       

     OPERATION 
     FIGS.  15 A to  15 C—Alternative 4 of Third Embodiment 
     Alternative 4 illustrated in  FIGS. 15A ,  15 B and  15 C, operates in the same way as the alternative 3 illustrated in  FIGS. 14A ,  14 B and  14 C. 
     DETAILED DESCRIPTION 
     FIGS.  16 A to  16 C—Forth Embodiment 
     The forth embodiment is illustrated in  FIG. 16B  (perspective view of normal horizontal flight configuration),  FIG. 16C  (perspective view of VTOL configuration with landing gears extended),  FIG. 16A  (perspective view of ground vehicle configuration with wings folded),  FIG. 16D  (front view with vertical stabilizer in winglet configuration) and  FIG. 16E  (front view with vertical stabilizer in up right vertical position). The upright vertical configuration of vertical stabilizer is used in formation flight. Overall structure of the forth embodiment can be generally viewed as 2 V shape wings connected head to head and formed general X shape. 
     Roots of inner wing  4011  and  40013  are connected to center fuselage  4060  at its left and right side respectively. Tips of inner wing  4011  and  40013  are connected to side fuselage  4062  and  4064  respectively. Roots of left front wing  4009  and left rear wing  4010  are connected to left side of left side fuselage  4062 . Roots of right front wing  4008  and right rear wing  4012  are connected to right side of right side fuselage  4064 . Left vertical stabilizer  4016  and right vertical stabilizer  4014  are connected to tips of left rear wing  4010  and right rear wing  4012  respectively. Horizontal stabilizer  4018  is disposed between 2 side fuselages. Left and right tip of horizontal stabilizer  4018  are connected to rear ends of fuselage  4062  and  4064  respectively. 
     Rear thrust generator  4020  is disposed at the intersection of tail of center fuselage  4060  and ream beam  4032 . Two ends of rear beam  4032  are connected to inner sides of fuselage  4062  and  4064 . Rear end of left front mini side fuselage  4066  is connected to left side of front end of left side of fuselage  4062 . Rear end of right front mini side fuselage  4068  is connected to right side of front end of right side of fuselage  4064 . Two ends of front beam  4030  are connected to inner sides of front mini side fuselage  4066  and  4068 . Front beam  4030  passes through center fuselage  4060 . Front left thrust generator  4022  and front right thrust generator  4024  are disposed at left and right side of front beam  4030  respectively. 
     Front landing gear  4050  is connected to the front bottom side of center fuselage  4060 . It rotates back and forth to its retracted and extended position respectively. Left landing gear  4052  is connected to the rear bottom side of left side fuselage  4062 . It rotates left and right to its retracted and extended position respectively. Right landing gear  4054  (obstructed in  FIGS. 16B and 16C ) is connected to the rear bottom side of right side fuselage  4064 . It rotates right and left to its retracted and extended position respectively. 
     OPERATION 
     FIGS.  16 A to  16 E—Forth Embodiment 
     The forth embodiment illustrated in  FIG. 16A to 16E  operates in the same way as the alternative embodiment 3 (of the third embodiment) illustrated in  FIGS. 14A ,  14 B and  14 C. Moment component calculation equation (9)-(11) apply to both embodiments despite the reverse order of center thrust generator and 2 side thrust generators, so the way to control rotation motion is the same for both embodiments. And the reverse order of thrust generators does not affect the way to control translational motion. 
     DETAILED DESCRIPTION 
     FIG.  17 —Alternative 1 of Forth Embodiment 
     An alternative of the forth embodiment is illustrated in  FIG. 17  (perspective view. It has the same structure as the forth embodiment, except center fuselage is in shape of Goldschmied airfoil shown in  FIG. 4  in order to reduce drag and increase lift, and horizontal stabilizer is removed. The pitching rotation is controlled by flaperon of the pivotable control surface disposed at trailing edge close to root of 2 rear wings. 
     OPERATION 
     FIG.  17 —Alternative 1 of Forth Embodiment 
     Except there is blower ( 402  in  FIG. 4 ) to operate in order for center fuselage to function as Goldschmied airfoil, alternative embodiment 1 illustrated in  FIG. 17  operates in the same way as the forth embodiment illustrated in  FIG. 16A to 16C . 
     DETAILED DESCRIPTION 
     FIG.  18 —Alternative 2 of Forth Embodiment 
     An alternative of the forth embodiment is illustrated in  FIG. 18  (perspective view). It has the same structure as the forth embodiment, except thrust generators are in a particular form of ducted fan. 
     OPERATION 
     FIG.  18 —Alternative 2 of Forth Embodiment 
     Alternative embodiment 2 illustrated in  FIG. 18  operates in the same way as the forth embodiment illustrated in  FIG. 16A to 16C . 
     DETAILED DESCRIPTION 
     FIG.  19 A to  19 C—Alternative 3 of Forth Embodiment 
     An alternative of the forth embodiment is illustrated in  FIG. 19A  (perspective view). It has the same structure as the forth embodiment, except center fuselage is slimmer in order to reduce drag. It&#39;s intended for unmanned applications. 
       FIGS. 19B and 19C  illustrate a particular implementation of powertrain for thrust generation. It&#39;s given as an exemplar implementation of powertrain, and it should not be used to limit scope of this invention. 
     Worm gear set  4075 ,  4076  and  4077 , gear and belt assembly  4078 ,  4089 , and  4080 , and bearing  4089  are illustrated better in perspective view  FIG. 19B . In top view  FIG. 19C , engine  4025  drives shaft  4086 , which in turn drives gear box  4070 . In gear box  4070 , input bevel gear is connected to the end of shaft  4086 , and it drives an intermediate bevel gear, which is connected shaft  4087  via a bearing so that rotating shaft  4087  won&#39;t cause the intermediate bevel gear to rotate around shaft  4087 . The intermediate bevel gear drives output bevel gear. Output bevel gear connects to an output shaft, which is connected to frame of gear box via a bearing. The output shaft drives a propeller. Shaft  4087  is disposed inside ream beam, and runs through gear box  4070 . Frame of gear box  4070  is fixed to shaft  4087 .  4089  is a bearing supporting shaft  4087  at its un-driven end. 
     Disposed inside right side fuselage, motor  4023  drives worm gear set  4077 , which drives gear and belt assembly  4080 , which in turn drives shaft  4087 . Shaft  4087  drives gear box frame, which in turn drives the output shaft, the propeller and the output bevel gear to rotate around shaft  4087  while the output bevel gear is maintaining contact with the intermediate bevel gear. Therefore 2D thrust vectoring is realized. 
     When engine  4026  and  4027  are electric engines, but engine  4025  is not an electric engine, engine  4025  can also drive an electric generator to power engine  4026  and  4027 , and store extra electricity into onboard battery. 
     2D thrust vectoring of 2 front thrust generators works in similar way. Disposed inside front section of center fuselage, engine  4026  and  4027  drive bevel gear set  4073  and  4074  via shaft  4085  and  4084  respectively. Output bevel gears of bevel gear set  4073  and  4074  are connected to shaft  4083  and  4082  respectively. There are bearings between shaft  4081  and  4082 , and between shaft  4083  and  4088  so that rotations of shaft  4082  and  4083  are independent of rotations of shaft  4081  and  4088 . Shaft  4081  and  4088  rotate independently. 
     Disposed inside left and right side fuselage respectively, motor  4028  and  4029  drive worm gear  4075  and  4076  respectively. Worm gear  4075  and  4076  drives gear and belt assembly  4078  and  4079 , which in turn drive shaft  4088  and  4081  respectively. Shaft  4088  and  4081  drive frames, output bevel gears and propellers associated with gear box  4071  and  4072  to rotate around shaft  4088  and  4081  respectively. Therefore 2D thrust vectoring of 2 front thrust generators is realized. 
     OPERATION 
     FIGS.  19 A to  19 C—Alternative 3 of Forth Embodiment 
     Alternative embodiment 3 illustrated in  FIG. 19A to 19C  operates in the same way as the forth embodiment illustrated in  FIG. 16A to 16C . 
     COMBINABILITY 
     FIGS.  6 A to  6 C and  20 A to  20 K—Embodiments of Formation 
     All embodiments in this invention are designed to be able to combine with other embodiments to form larger vehicles of a wide variety of shapes as shown in  FIG. 20A to 20K . The combined vehicles are also capable of VTOL. Embodiments of different types can coexist in one combination. An easier way to combine vehicles together is to manually assembly them on the ground before takeoff. A sophisticated way is to automatically rendezvous and dock in flight. 
     A system for in-flight rendezvous and docking is shown in  FIG. 6A to 6C . The system is similar to “probe and drogue” system used in aerial refueling. The main function of “probe and drogue” system is to transfer fuel in the flight. The system shown in  FIG. 6A to 6C  has 2 main functions:
         1. To rendezvous and dock in flight   2. To transfer fuel or electricity       

     Another difference is that in “probe and drogue” system fuel tank aircraft and fuel receiver aircraft align longitudinally; the system shown in  FIG. 6  works in both longitudinal and lateral mode. 
     In lateral mode, as shown in  FIG. 6A  (it works in similar way when base tube  905  is on the left side of base tube  904 ), base tube  905  and  904  extends out from wing tip of front and rear aircraft respectively. Two aircraft first come to close formation under the guide of differential GPS sub-systems on 2 aircraft. When docking probe  900  is approximately behind drogue fingers  909 , optoelectronic device  902  and  907  inside docking probe  900  and drogue arm  906  respectively, work together with the onboard differential GPS sub-systems to guide the in-flight rendezvous and docking process. Under the guidance, docking probe  900  moves forward into the funnel shaped space surrounded by drogue fingers  909 , and it&#39;s will be captured by closing drogue fingers  909 . Probe  900  can be rotated around axis  903 , which is connected to base tube  904 . Drogue arm  906  can be rotated around axis  908 , which is connected to base tube  905 . The rear aircraft, which is equipped with docking probe  900 , then turns slight sideway while moving forward slowly. The system will reach configuration where component  900  to  908  are approximately lined up as shown in  FIG. 6C . In the next step, drogue arm  906  pulls docking probe  900  in and completes the in-flight rendezvous and docking procedure. 
     In longitudinal mode, as shown in  FIG. 6B , it works similarly, and the whole process is simpler. Base tube  904  still extends out from wing tip of rear aircraft. Base tube  905  extends out from rear end of front aircraft. After drogue fingers  909  capture docking probe  900 , drogue arm  906  pulls docking probe  900  in and completes the in-flight rendezvous and docking procedure. 
     The combinability enables whole new set of opportunities. The following are some of possible applications enabled by the combinability:
         1. Multiple embodiments are combined together to form a larger aircraft, which is capable of carry large payload that exceeds load capacity of individual embodiment.   2. In a formation of multiple embodiments, some of individual embodiments are dedicated to carry fuel acting as fuel tankers. Such fuel tankers may leave formation before reaching targets. Such formation has larger operation radius than that of single aircraft of similar type.   3. In-flight rendezvous and docking can be used to create buddy refueling system. Before an embodiment reaching target zone or after it leaves target zone, other embodiments can dock with it and refuel it. Thus operation radius of single embodiment is increased. Buddy refueling system also allows an embodiment to carry more payloads. An aircraft&#39;s maximum takeoff weight is generally less than the maximum weight with which it can stay airborne. Buddy refueling system allows an embodiment to take off with only a partial fuel load, and carry additional payload weight instead. Then, after reaching altitude, its tanks can be topped up by a tanker embodiment, bringing it up to its maximum flight weight.   4. A formation of multiple embodiments offers large redundancy, and therefore has greater chance to accomplish missions. Each embodiment in the formation is autonomous. When the formation is large, the chance of being completely destroyed in the first few attacks is small. When damage occur, the formation has the following options:
           a. When damage is small, carry on the damaged embodiments, and continue on the mission. In this case, the damaged embodiments, which would otherwise be lost, can be carried back to base and repaired. Thus in long run, operation cost will be smaller.   b. When damage is large, disengage and discard the damaged embodiments, reconnect formation, and continue on the mission.   
           Also when threats coming, the formation might have chance to disengage, spread out to reduce damage, and re-dock later to form formation again.