Patent Publication Number: US-2023140370-A1

Title: Vtol rotorcraft with annular contra-rotating rotary wings and auxiliary propulsor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     
         
         U.S. Pat. No. 7,210,651B2 May 1, 2007 Mark Winfield Scott B64C27/10 
         US20090321554A1 Dec. 31, 2009 Philippe ROESCH B64C27/26 
         U.S. Pat. No. 8,403,255B2 Mar. 26, 2013 Frederick W. Piasecki B64C27/26 
         U.S. Pat. No. 8,876,057B2 Nov. 4, 2014 Mark R. Alber, B64C27/26, B64C27/10 
         US20160101852A1 Apr. 14, 2016 Yun Jiang B64C27/20 
         US20180257771A1 Sep. 13, 2018 Mark W. Scott B64C2027/8236, B64C27/10 
         U.S. Pat. No. 10,562,618B2 Feb. 18, 2020 Daniel Bryan Robertson B64C27/26, B64C2201/024, B64C9/04 
         U.S. Pat. No. 10,703,472B2 Jul. 7, 2020 Mark W. Scott B64C2027/8281, B64C27/10, 
       
    
    
    
     BACKGROUND ON THE INVENTION 
     The helicopter is an essential modern air transportation vehicle. Rotorcraft and rotary-wing vehicle are the technical term designated for aircraft with rotating wing, which provides lift, propulsion and steering control. Rotorcraft can land and take-off without the presence of long run way. However, travelling in a helicopter is expensive, due to the high operational cost. Moreover, helicopter with fossil fuel engine flying over an urban area is known to be a source of noise and air pollution. 
     The world of aviation is under pressure to reduce emission. As a result, there is numerous new designs of E-VTOL (electrical vertical take-off and landing) rotorcraft in progress today, and the term UAM (urban air mobility) is adopted for this type of personal or cargo aerial transportation. An E-VTOL rotorcraft is quiet, emission free and low operational cost. 
     As the traffic delay is increasing busy in the global urban area, an affordable E-VTOL rotorcraft is the solution for daily commuter to avoid the congestion on the road. Without traffic delay, an affordable E-VTOL rotorcraft can also be used as law enforcement vehicle, ambulance and medical cargo transporter. 
     Since the weight of electrical energy storage accounts for a large fraction of the total weight of the E-VTOL rotorcraft, it is paramount to design an electrical rotorcraft with higher propulsion thrust and lift thrust efficiency. The electrical energy storage for electrical rotorcraft is not limited to electrical battery or fuel cell. Based on the momentum theory of propeller, high disc loading leads to lower lift thrust efficiency. Therefore, higher power is required to lift the aircraft and more energy is consumed to hover and flight. The best demonstration of this theory can be found in human powered rotorcraft. The human powered rotorcraft with multiple giant rotary wings is as large as the size of a basketball court. The disc area must be very large, in order to reduce the disc loading and increase lift thrust efficiency, therefore a person can provide the required power to hover the rotorcraft. However, long light weight blade has limited strength and non-practical for landing on a small area. Moreover, longer blade increases of the risk of impact surrounding obstacle and human. 
     TECHNICAL FIELD 
     The disclosed invention is related to VTOL rotorcraft with auxiliary propulsor. It is also known as the compounded helicopter. 
     DISCLOSURE OF PRIOR ART 
     Traditionally, helicopter contains a single large main rotary wing for lift, propulsion and steering control. Helicopter is distinctive by the tail rotor to balance the torque effect of the main rotary wing. A significant amount of energy is wasted in the tail rotor in hover and low-speed flight. In order to eliminate the need for the tail rotor, the contra-rotating rotary wings were introduced in helicopter design. The contra-rotating rotary wings can balance the torque effect and increase power without increase in propeller frontal diameter. A light weight civilian helicopter with large rotary wing is known to have lower disk loading, which benefits from the large disk area. As a result, the lift thrust efficiency is the highest among all the VTOL (vertical take-off and landing) vehicle. The fact that helicopter has large rotary wing with very high inertia, it is difficult to reduce or increase the rotational speed of the blade without significant lag in response time. As a result, helicopter&#39;s rotary wing operates at constant speed, and the pitch of the blade is changed by the swash plate mechanism. The swash plate mechanism is linked to the collector and cyclic to steer the helicopter, which is a complex and heavy equipment. Naturally, both single rotor or contra-rotating rotary wings have the complex mechanical swash plate system. 
     The arrival of distributed electrical propulsion system allows modern multirotor to substitute the traditional helicopter. The electrical propulsion system contains multiple independent smaller rotary wings to provide lift, propulsion and steering control. Quad-rotorcraft is a popular design for electrical rotorcraft, since it contains four moving parts, which are the four rotary wings. The fixed pitch smaller rotary wing has low inertia, which allows the speed of the rotating blade to be decreased or increased rapidly. The modulation of the power setting on the rotary wings provides lift, propulsion and steering control. The disadvantage of the four rotary wings propulsion is that the rotary wing is smaller in diameter. Based on the momentum theory, this type of small diameter rotary wing is low in thrust lift efficient, mainly caused by the high disc loading. The multi-rotor rotorcraft is advantageous for safety redundancy, in comparing to a single rotary wing helicopter. 
     The primary object of the present invention is to disclose a novel VTOL rotorcraft with an efficient rotary wing propulsion system benefitting from the simplicity and safety of a multirotor rotorcraft. Moreover, an auxiliary propulsor to increase forward flight speed. 
     SUMMARY OF THE INVENTION 
     1. In one embodiment of the VTOL rotorcraft is provided, comprising of a contra-rotating rotary wings, a nacelle, a fuselage, a tail boom, an auxiliary propulsor. 
     2. Also in one embodiment of the contra-rotating rotary wings is provided, comprising of an upper rotary wing and a lower rotary wing driven by direct drive motor. 
     3. In another embodiment of the contra-rotating rotary wings is provided, comprising of an upper rotary wing and a lower rotary wing driven by multiple independent motors. 
     4. In another embodiment of the contra-rotating rotary wings is provided, comprising of an upper rotary wing and a lower rotary wing steered by multiple independent actuators. 
     5. In one embodiment of the auxiliary propulsor is provided, comprising of quad independent pusher propellers, a least one directional rudder, and pitch control elevators. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Regarding the invention disclosure, the feature and advantage of the invention are particularly pointed and distinctly claimed in the claims. Detailed description and methods are given to provide further comprehension of the functionality of the invention. It should be observed that three mutual orthogonal directions X, Y, and Z are shown in some of the FIGS. The first direction X is said to be “longitudinal”, and the forward side is referenced to be positive. The second direction Y is said to be “transverse”, and the port side is referenced to be positive. Finally, the third direction Z is said to be “vertical”, and the up side is referenced to be positive. Moreover, it should be observed that force vector is shown in dash lead arrow. 
         FIG.  1    is a perspective view of the embodiment of the VTOL rotorcraft with annular contra-rotating rotary wings and auxiliary propulsor. 
         FIG.  2    is a perspective view of the embodiment of the contra-rotating rotary wings with direct drive prime mover. 
         FIG.  3    is a side view of the embodiment of the contra-rotating rotary wings of  FIG.  2   . 
         FIG.  4    is an exposed top plan view of the embodiment of  FIG.  2   . 
         FIG.  5    is a top plan view of a diagram showing the reaction forces acting on the stator hub of the embodiment of  FIG.  2    during vertical flight. 
         FIG.  6    is a top plan view of a diagram showing the reaction force vectors acting on the stator hub of the embodiment of  FIG.  2    during forward fight. 
         FIG.  7    is a side view of a diagram showing the force vectors of the contra-rotating rotary wings of  FIG.  2    during forward flight. 
         FIG.  8    is a top plan view of a diagram showing the reaction force vectors acting on the stator hub of the embodiment of  FIG.  2    during backward flight. 
         FIG.  9    is a side view of a diagram showing the force vectors of the contra-rotating rotary wings of  FIG.  2    in the pitch backward flight. 
         FIG.  10    is a perspective view of another embodiment of the contra-rotating rotary wings with multiple prime movers. 
         FIG.  11    is top plan view of the embodiment of  FIG.  10   . 
         FIG.  12    is a perspective view of the embodiment of the actuated contra-rotating rotary wings. 
         FIG.  13    is a perspective view of the embodiment of the auxiliary propulsor. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG.  1    is a perspective view of the embodiment of the VTOL rotorcraft  100 , which comprises of the contra-rotating rotary wings  101 , a nacelle  102 , a fuselage  103 , a tail boom  104  and an auxiliary propulsor  105 . The contra-rotating rotary wings  101  and a nacelle  102  are mechanical secured together. The assembly of contra-rotating rotary wings  101  and nacelle  102  are mechanical linked through universal joint to the fuselage  103 , therefore the assembly of contra-rotating rotary wings  101  and nacelle  102  can pivot relative to the fuselage  102 . The nacelle  102  is shrouded around the contra-rotating rotary wings  101 , it is also known as the ducted fan. The ducted fan is more efficient and save energy due to the following two points. Firstly, the nacelle helps to eliminate blade tip vortex and downstream flow contraction. Secondly, the nacelle generates additional lift, due to the low-pressure air field on the upper surface of the nacelle inlet lip. Acoustic suppression is integrated in the inner surface of the nacelle to reduce the noise from the contra-rotating rotary wings  101 . Moreover, the nacelle  102  serves as a shield to protect the blade from impacting surrounding obstacle or human. Without departing from the scope of the invention, the nacelle  102  can be circle, oval, triangle or tear drop shape outer mold line to reduce drag and generate lift during forward flight. 
       FIG.  2    is a perspective view the embodiment of the contra-rotating rotary wings  101 , which comprises of the upper rotary wing  106  and the lower rotary wing  107 . The upper rotary wing  106  and the lower rotary wing  106  share the same axis of rotation. The pair of rotary wings rotate in the opposing direction. As a result, the thrust is symmetrical at all moving speed in all direction. The contra-rotating rotary wings can self-contain the torque effect in the yaw axis of the rotorcraft. Therefore, a rotorcraft with contra-rotating rotary wings has no need for counter yaw tail boom rotor. In the example, the rotational direction of the upper rotary wing  106  is represented by arrow  108  and the rotational direction of the lower rotary wing  107  is represented by arrow  109 . For example, if the total torque applied to the upper rotary wing  106  and lower rotary wing  107  are equal, therefore the total torque effect is zero on the vertical axis. For example, if higher torque is applied to the upper rotary wing  106 , and it is turning to the direction as shown by the arrow  108 , which results the yaw movement on the vertical axis to the port side. For example, if higher torque is applied to the lower rotary wing  107 , and it is turning to the direction as shown by the arrow  109 , which results the yaw movement on the vertical axis to the starboard side. As a result, the rotary wings can adjust directional heading of the rotorcraft on the horizontal plan. 
     The contra-rotating rotary wings  101  can maneuver up and down, by adjusting the speed of the rotary wings. The increase of the speed simultaneously on the upper rotary wing  106  and lower rotary wing  107  generates more thrust to move the rotorcraft upward on the vertical axis. The reduction of the speed simultaneously on the upper rotary wing  106  and lower rotary wing  107  generates lesser thrust, which allows gravity to pull the rotorcraft downward on the vertical axis. 
       FIG.  3    is a side view of the embodiment of contra-rotating rotary wings  101 . The upper rotary wing  106  and lower rotary wing  107  are offset vertically. 
       FIG.  4    is a plan view of the embodiment of the upper rotary wing  106  and lower rotary wing  107 . The rotary wings  106  and  107  having the identical direct drive prime mover architecture, which comprising of an inner fixed stator hub  110 , the outer rotor  111 , a plurality of rotary wing blades  112 . The example shown with four rotary wing blades for illustration purpose, but it is not limited to four rotary wing blades. The stator hub  110  and outer rotor  111  are concentric. The upper rotary wing  106  and lower rotary wing  107  are mechanical secured together through the stator hub  110 . The prime mover composed of an array of stator windings  113  fixed along the circumference of the stator hub  110 . Moreover, an array of magnet  111   a  mounted along the circumference of the outer rotor  111 . This motor architecture is known as direct drive motor or frameless motor. When the stator windings  113  are energized, a magnetic force is produced between the rotor magnet  111   a  and the stator windings  113 . This magnetic force produces a tangential pulling and pushing force on the outer rotor  111 . This tangential force is converted to torque force to turn the outer rotor  111 . The magnetic force produces an equal reaction force acting on the stator hub  110 . A plurality of rotary wing blades  112  is attached to the outer rotor  111 . When the outer rotor  111  is rotating, lift is generated by the plurality of rotary wing blades  112 . The thrust downstream of the blade is a resulting force of lift. Thrust is not generated within the hollow space of the stator hub  110 . The fuselage  103  is located along the center of the rotary wing rotational axis. Therefore, the fuselage  103  is not an obstacle of the thrust generated by the rotary wing. As a result, the rotary wing has a higher propulsive thrust efficiency. The second factor that increases the overall rotary wing efficiency is the large annular disc area. The momentum theory states that larger rotary wing with lower disc loading has higher lift efficiency. The design benefits from the large disc area, therefore lesser energy is needed to hover or maintain leveled flight. The blade can be made shorter and stronger. For a constant rotational speed, it is possible to increase the lift capacity, by increasing the number of blade or employing blade of different span/chord aspect ratio. Moreover, a large diameter rotary wing provides greater authority to steer and level the rotorcraft. 
     The array of stator windings  113  of the drive motor is divided into four partitions  110   a ,  110   b ,  110   c ,  110   d . In other words, each partition acts as an independent prime mover. Each stator partition covers 90 degrees span of the stator hub. The forward direction is used as reference at degree 0. Partition  110   a  covers from 315 degree to 45 degree span of the stator hub  110 . Partition  110   b  covers from 45 degree to 135 degree span of the stator hub  110 . Partition  110   c  covers from 135 degree to 225 degree span of the stator hub  110 . Partition  110   d  covers from 225 degree to 315 degree span of the stator hub  110 . All four partitions are driving the rotary wing to rotate at the same speed. However, the magnetic force of each partition of stator is independently modulated. As a result, the uneven tangential forces created by partition  110   a ,  110   b ,  110   c ,  110   d  can tilt the rotational axis of the rotary wing to steer the rotorcraft in the pitch and roll axis. 
       FIG.  5    is a schematic plan view of the tangential reaction force vectors acting on the rotary wing during hover. All tangential forces produced by the stators of the same partition is summed into a single tangential reaction force. The four reaction forces are perpendicularly acting on the stator hub  110  at location 0 degree, 90 degrees, 180 degrees, 270 degrees of the upper rotary wing  106  and lower rotary wing  107 . The partition is showed as  114 ,  115 ,  116 ,  117  on the upper rotary wing  106 . The partition is showed as  118 ,  119 ,  120 ,  121  on the lower rotary wing  107 . The reaction force acting on the upper rotary wing  106  is represented by vector  114   a ,  115   a ,  116   a ,  117   a . The reaction force acting on the lower rotary wing  107  is represented by vector  118   a ,  119   a ,  120   a ,  121   a  on the lower rotary wing  107 . If the magnetic force is produced evenly by all four partitions of stator on the upper rotary wing  106  and lower rotary wing  107 , it can be observed that all vectors have the same magnitude. Therefore, the moment couples relative to the center of gravity of the rotorcraft created by vector  114   a ,  115   a ,  116   a ,  117   a ,  118   a ,  119   a ,  120   a ,  121   a  are net zero. 
       FIG.  6    is a schematic plan view of a of the tangential reaction force vectors acting on the rotary wing in forward flight. The increase of magnetic force in partition  115  of the upper rotary wing  106  and  121  of the lower rotary wing  107 , resulting the tangential reaction force vector  115   b  and  121   b  to increase in magnitude. The magnitude of tangential force of partition  114   b ,  116   b ,  117   b ,  118   b ,  119   b ,  120   b  are equal. All the moment couples created by vector  114   b ,  116   b ,  117   b ,  118   b ,  119   b ,  120   b  are net zero to the rotorcraft. The vector  115   b  and  121   b  contribute to the net moment to steer the rotational axis of the contra-rotating rotary wings to turn forward along the Y axis. The higher ratio of the vector magnitude  115   b  and  121   b , relative to vector magnitude  114   b ,  116   b ,  117   b ,  118   b ,  119   b ,  120   b , the more the rotorcraft can pitch forward and move faster. 
       FIG.  7    is a side schematic view of a of the resulting forcing acting on the rotorcraft in forward flight. The center of gravity of the rotorcraft is represented by the center of gravity symbol. The rotorcraft mass times gravity is represented by vector F(mg). The lift generated by the contra-rotating rotor wings  101  is represented by vector F(lift). The vector F(lift) is broken down to vertical vector F(Z) and horizontal vector F(X). The vector F(Z) balances with vector F(mg), and vector F(X) moves the rotorcraft forward. 
       FIG.  8    is a schematic plan view of a of the tangential reaction force vectors acting on the rotary wing in backward flight. The increase of magnetic force in partition  117  of the upper rotary wing  106  and  119  of the lower rotary wing  107 , resulting the tangential reaction force vector  117 C and  119 C to increase in magnitude. All the moment couples created by vector  114 C,  115 C,  116 C,  118 C,  120 C,  121 C are net zero to the rotorcraft. The vector  117   b  and  119   b  contribute to the net moment to steer the rotational axis of the contra-rotating rotary wings to turn backward along the Y axis. The higher ratio of the vector magnitude  117 C and  119 C, relative to vector magnitude  114 C,  115 C,  116 C,  118 C,  120 C,  121 C, the more the rotorcraft can pitch backward and move faster. 
       FIG.  9    is a side schematic view of a of the resulting forcing acting on the rotorcraft in backward flight. The center of gravity of the rotorcraft is represented by the center of gravity symbol. The rotorcraft mass times gravity is represented by vector F(mg). The lift generated by the contra-rotating rotor wings  101  is represented by vector F(lift). The vector F(lift) is broken down to vertical vector F(Z) and horizontal vector-F(X). The vector F(Z) balances with vector F(mg), and vector-F(X) moves the rotorcraft backward. 
     Referencing to back to  FIG.  5   . Similar principle can be applied to roll the rotorcraft to the port side, by increasing of magnetic force in partition  114  of the upper rotary wing  106  and  120  of the lower rotary wing  107 . Furthermore, similar principle can be applied to roll the rotorcraft to the starboard side, by increasing of magnetic force in partition  116  of the upper rotary wing  106  and  118  of the lower rotary wing  107 . 
       FIG.  10    is a perspective view of a second embodiment of the contra-rotating rotary wings  1000 , which comprises of the upper rotary wing  1001  and the lower rotary wing  1002 . The upper rotary wing  1001  and the lower rotary wing  1002  share the same axis of rotation. In the example, the rotational direction of the upper rotary wing  1001  is represented by arrow  1003  and the rotational direction of the lower rotary wing  1002  is represented by arrow  1004 . 
       FIG.  11    is a plan view of the embodiment of the upper rotary wing  1001  and lower rotary wing  1002 . The rotary wing  1001  and  1002  have the identical multiple motor drive architecture, which comprising of a fixed inner hub  1005 , a plurality of prime moves  1006 , the outer spinner  1007 , a plurality of rotary wing blades  1008 . The example shown with four rotary wing blades for illustration purpose, but it is not limited to four rotary wing blades. The upper rotary wing  1001  and lower rotary wing  1002  are mechanical secured together through the inner hub  1005 . The plurality of prime movers  1006  is mounted evenly 90 degrees apart along the circumference of the inner hub  1005 . In detail, two of the plurality of prime movers  1005  are intersecting the X-axis, and the other two of the plurality of prime movers  1006  are intersecting the Y-axis. The outer spinner  1007  can be driven by the plurality of prime movers  1006 , through different method of mechanical coupling, such as gear, belt, chain, viscous coupling or direct friction. The rotary output motion of the plurality of prime movers  1006  is converted into tangential force to rotate the outer spinner  1007 . The prime mover  1006  is not limited to electrical motor, pneumatic driven motor and hydraulic driven motor. Moreover, the outer spinner  1007  can be directly driven by tangential force provided by a hydraulic or pneumatic system. The contra-rotating rotary wings  1000  operates the same way as contra-rotating rotary wings  101 . The uneven tangential forces created by the plurality of primes moves can tilt the rotational axis of the rotary wing to steer the rotorcraft in the pitch and roll axis. 
       FIG.  12    is a side view of the embodiment of the actuated contra-rotating rotary wings  1200 . An actuated contra-rotating rotary  1200  comprising of the upper rotary wing  1201 , the lower rotary wing  1202 , and a plurality of linear actuators  1203 . A plurality of linear actuators  1203  can also be mated with either contra-rotating rotary wings  101  or contra-rotating rotary wings  1000 . The upper rotary wing  1201  and the lower rotary wing  1202  are mechanical secured together at the fixed inner hub. The plurality of the of linear actuators is mechanical linking the contra-rotating rotary wings  1200  to the airframe. The plurality of linear actuators can be electrical actuator, lever arm actuator, jackscrew actuator, hydraulic actuator and torque motor actuator. The example shown with four actuations for illustration purpose, but it is not limited to four actuations device. For example, an actuated platform with six actuations device is known as an industrial device namely Stewart Platform. The four linear actuators work together to steer the rotational axis of the rotary wing. As result, the change of thrust vector relative to the fuselage permits the rotorcraft to hover, fly forward, backward and sideward. 
       FIG.  13    is a perspective view of the embodiment of the auxiliary propulsor  105 . In detail, auxiliary propulsor  105  comprising of quad ducted pusher propellers  105   a ,  105   b ,  105   c  and  105   d  driven by independent prime mover, at least one directional rudder  105   e , and the transversally extended elevators  105   f . The pusher propellers  105   a ,  105   b ,  105   c  and  105   d  are positioned as a 2×2 matrix. The rotational axis of the propellers is aligned with the longitudinal axis of the rotorcraft. The auxiliary propulsor  105  is mounted to the fuselage  103  through the rear tail boom  104 . The propeller  105   a ,  105   b ,  105   c  and  105   d  can be ducted or unducted fan. propeller system  105   a  and  105   d  are rotating clockwise direction. Propeller system  105   b  and  105   c  are rotating counterclockwise direction. The direction of rotating the propeller system can also be reversed of the previous described direction. The mounting location of the auxiliary propulsor  105  is intended to clear the slipstream of the rotary wing. The quad propellers are a redundancy feature, comparing to a single larger propeller. Naturally, the quad propellers propel the rotorcraft to achieve a faster forward speed. The directional rudder  105   e  can direct thrust sideward. The sideward thrust is used for directional heading control and also acts as a counter torque effect device in the event of a failure in one of the two main rotary wings. The elevators  105   f  are used for pitch control of the rotorcraft. During forward flight, the rotary wings can be unpowered in autorotation mode, and the forward thrust is provided by the quad propellers. The rotary movement of the rotary wing is resulting from the forward speed, therefore lift is generated by the rotary wing to maintain the rotorcraft air born. 
     The disclosure has been described with reference to particular embodiments, it should be understood that the embodiments are for illustrative and explanatory purpose. There are numerous variations, modifications and configurations which may be made hereto without departing from the scope of the subject disclosure. In one possible configuration, the dual annular contra-rotating rotary wings can be used on a tandem rotorcraft. By definition, a tandem rotorcraft is a vehicle with a rotary wing in the front section the fuselage and second rotary wing in the rear section of the fuselage. The tangential forces which provide rotary movement to the rotary wing can be provided by different type of magnetic drive system, motor drive system, pneumatic drive system and hydraulic drive system. The tangential forces can also be applied at the end tip of the blade. Nevertheless, the invention is applicable to any multirotor vehicle of arbitrary weight, such as a light drone to a large tonnage vehicle.