The disclosed invention relates to a VTOL (vertical take-off and landing) box-wing aerial vehicle, and more specifically to the configuration of the box-wing airframe configurated with multiple rotary wings for VTOL flight and the tiltable rotor or push rotor for forward flight.
The helicopter is an essential modern air transportation vehicle. Technically, helicopter with rotary wing is also referred as “rotorcraft” or “rotary wing vehicle”. The rotary wing is commonly referred as “rotor”. Rotary wing positioned in the center of a shroud is called “ducted fan”. In general, rotary wing consists of propeller comprising of a plurality of blades. The rotary movement of the blades works as the air mover to generate thrust. The rotary wing permits the helicopter to land and take-off vertically without the presence of a long run way. Disadvantageously, helicopter with fossil fuel engine is associated with expensive operational cost, undesirable high level of noise and carbon emission.
As the traffic is increasing heavy in the global urban area, an affordable electrical VTOL vehicle is the solution to avoid the congestion on the road. Without traffic delay, an electrical VTOL vehicle can also operate as law enforcement vehicle, ambulance and medical cargo transporter. A new term UAM (urban air mobility) is adopted for this new type of aerial transportation.
Modern electrical VTOL vehicle with multiple rotary wings is known as multirotor vehicle. The multiple rotary wing system provides an agile steering capability. The energy required for VTOL flight is significantly higher than the energy required for a fix wing airplane to maintain forward flight. Advantageously, modern electrical VTOL vehicle also has the capability to transition to airplane mode for forward flight. During forward flight, the VTOL vehicle is depending on the forward speed to generate lift from the fixed wings. Furthermore, the propulsive movement is generated by a push rotor or tiltable rotor.
Traditional fixed wing aircraft suffers from significant loses of lift efficiency at the tip of the wings, due to the occurrence of vortex. As a result, winglet, sharklet and box-wing design is introduced to improve lift efficiency.
A bigger challenge for VTOL vehicle to operates safety near the ground, by maintaining safe distance between the rotating blade and the person or object.
In one embodiment of the invention a box-wing multirotor vehicle with both VTOL and airplane forward flight capability is provided, comprising a detachable cabin, a fuselage base having a longitudinal axis, fixed wings having a biplane arrangement, a pylon secured to the fixed wings at the tip, a pair of rudder, a pair of overhead boom, a pair of forward contra-rotating lift rotor, an tiltable lift and push rotor mechanically, a main landing gear pad or wheel, a horizontal and vertical stabilizer, a yaw servo tail boom, a rear contra-rotating lift rotor, and a nose landing gear pad or wheel.
Also in one embodiment the detachable cabin is separable from the box-wing multirotor vehicle for ground transportation. Also in one embodiment an overhead boom comprising of a plurality of lift rotors from the forward to the rear portion. Also in one embodiment the forward contra-rotating lift rotors and rear contra-rotating lift rotor exert firstly the lift needed for take-off, for landing, for hovering, and for flying vertically. Also in one embodiment the yaw servo tail boom directs thrust sideway to provide a complimentary control of the yaw heading. Also in one embodiment the tiltable lift and push rotor aiming in the downward position exerts complimentary lift needed for take-off, for landing, for hovering, for flying vertically. Also in one embodiment the tiltable lift and push rotor aiming in the aftward position provides the propulsive force for forward motion. Also in one embodiment the fixed wings provide the lift to the vehicle during forward flight. Also in one embodiment the rudder, elevator and aileron provide pitch, roll and yaw control during forward flight. Also in one embodiment the fixed wings can have a triplane arrangement.
In another embodiment of the invention a box-wing multirotor vehicle with both VTOL and airplane forward flight capability is provided, comprising a detachable cabin, a fuselage base having a longitudinal axis, fixed wings having a biplane arrangement, a pylon secured the fixed wings at the tip, a pair of rudder, a pair of overhead boom, a pair of forward contra-rotating lift rotor, a pair of rear contra-rotating lift rotor, a main landing gear pad or wheel, a horizontal and vertical stabilizer, a push rotor, and a nose landing gear pad or wheel.
Also in one embodiment the detachable cabin is separable from the box-wing multirotor vehicle for ground transportation. Also in one embodiment the overhead boom comprising of a plurality of lift rotors from the forward to the rear portion. Also in one embodiment the forward contra-rotating lift rotor and rear contra-rotating lift rotor exert firstly the lift needed for take-off, for landing, for hovering, and for flying vertically. Also in one embodiment the push rotor provides the propulsive force for forward motion. Also in one embodiment the fixed wings provide the lift for the vehicle during forward flight. Also in one embodiment the rudder, the elevator and aileron provide pitch, roll and yaw control during forward flight. Also in one embodiment the fixed wings can have a triplane arrangement.
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 FIGURES. The first direction X is said to be “longitudinal”, and the forward side is referenced to be positive. Rotational movement around the longitudinal axis is said to be “roll”. The second direction Y is said to be “transverse”, and the port side is referenced to be positive. And the Y plane is referenced as centerline of the vehicle. Rotational movement around the transverse axis is said to be “pitch”. Finally, the third direction Z is said to be “vertical”, and the up side is referenced to be positive. Rotational movement around the vertical axis is said to be “yaw”. Furthermore, the direction of motion is shown in dash arrow and axis of rotation is shown in dot dash line.
Advantageously, VTOL (vertical take-off and landing) vehicle can operate without a long runway. However, VTOL operation requires significantly higher energy than the energy required for a fixed wing aircraft to maintain forward flight. Therefore, the usefulness of VTOL vehicle is limited to short range flight. Modern VTOL is commonly designed with electrical power plant. In order to reduce the weight of electrical energy storage, an efficient VTOL vehicle can adapt to airplane mode for long range forward fight. In the disclosure of the invention, the technical term rotary wing is referred as “rotor”, and a rotary wing dedicated to generate lift is referred as “lift rotor”.
The operation of the box-wing multirotor vehicle 100 is descried in the following sections. Firstly, the box-wing multirotor vehicle 100 operates in the VTOL mode for taking-off, landing, hovering, and flying vertically. Secondly, the box-wing multirotor vehicle 100 operates in the fixed wing airplane mode for forward flight.
Advantageously in the VTOL mode, a plurality of independent electrical motors provides rotary movement to lift rotor 109, 110, 114 and 115. As a result, lift thrust is generated by the spinning lift rotor 109, 110, 114 and 115. Naturally, the lift forces propel the vehicle to taking-off, landing, hovering and flying vertically. Moreover, a mechanical system permits the tiltable lift and push rotor 111 to aim downward, therefore the produced thrust is also used for VTOL mode. The usage of tiltable lift and push rotor 111 is optional to increase the capacity of take-off payload or acts as redundant lift rotor. Firstly, the balance of thrust longitudinally and transversally allows the vehicle to fly levelly up and down in the Z axis. Secondly, an unbalance of thrust longitudinally allows the vehicle to pitch forward or aft, which allows the vehicle to fly forward and aftward. Finally, an unbalance of thrust transversally allows the vehicle to roll sideward, which allows the vehicle to fly side way. Optionally, the yaw servo tail boom 113 acts as a redundant flight control to assist the vehicle to change yaw heading.
Naturally, the torque effect of the rotor causes the vehicle to turn in the opposite direction of the rotor's spin. The lift rotor spins around the vertical axis, consequently the torque effect turns the yaw heading of the vehicle. Moreover, the magnitude of torque effect is proportional to the thrust produced by the rotor. In the case of the contra-rotating lift rotor, the torque effect is canceled out within every contra-rotating lift rotor. The dual lift and push rotors 111 are rotating in the opposite direction, therefore the torque effect is also cancelled out. As result, the vehicle maintains no yaw movement. In one aspect, the yaw heading adjustment is accomplished by increasing the thrust to the lift rotor spinning in one direction and reducing the thrust of the lift rotor spinning in the opposite direction. The unbalance of torque effect assists the vehicle to change yaw heading.
The operation of the box-wing multirotor vehicle 100 in airplane mode for forward flight is described in the following section. Firstly, after airborne, thrust produced by the tiltable lift and push rotor 111 is redirected to aim at the aftward direction, to propel the vehicle to the forward direction. Finally, until a cruising speed is reached, lift rotor 109, 110, 114 and 115 becomes unpowered, and the lift to maintain the vehicle airborne is provided solely by the wings. During airplane mode, the blade of lift rotor 109, 110, 114 and 115 are stowed in parallel with the longitudinal axis to reduce aerodynamic drag. Furthermore, the rudder 106, elevator 117 and aileron 118 provide the flight control capability to steer the vehicle in the pitch, roll and yaw axis. Moreover, horizontal and vertical stabilizer 112 provides directional stability for the vehicle.
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The operation of the box-wing multirotor vehicle 800 is described in the following sections. The box-wing multirotor vehicle 800 effectively has four dedicated contra-rotating lift rotors operating in the VTOL mode. Firstly, the quad contra-rotating lift rotors provide the lift thrust to box-wing multirotor vehicle 800 to operate in VTOL mode for taking-off, landing, hovering, and flying vertically. Moreover, the torque effect of the rotors assists the vehicle to change yaw heading. Secondly, in the fixed wing airplane mode, the push rotor 811 propels the vehicle forward to generate lift from the wings. Finally, until a cruising speed is reached, lift rotor 809, 810, 814 and 815 becomes unpowered, and the lift to maintain the vehicle airborne is provided solely by the wings. During airplane mode, the blade of the lift rotor 809, 810, 814 and 815 are stowed in parallel with the longitudinal axis to reduce aerodynamic drag. Furthermore, the rudder 806, elevator 817 and aileron 818 provide the flight control capability to steer the vehicle in the pitch, roll and yaw axis. Moreover, horizontal and vertical stabilizer 812 provides directional stability in forward flight mode.
Naturally, there are numerous variations, modifications and configurations which may be made hereto without departing from the scope of the disclosure invention. It should be understood that the embodiments are for illustrative and explanatory purpose and it is not conceivable to identify exhaustively all possible embodiments. In particular, it is important to observe that the invention as described relates in particular to an aerial multirotor vehicle with lift rotors secured to the box-wing. The design of the box-wing benefits from an improvement of structural strength, fatigue strength and load carrying strength. The box-wing permits the lift rotors to be secured to the upper portion of the vehicle, which prevents the rotating blade from striking a person or object near the ground. Finally, the box-wing with a plurality of main wings design permits the wing span to be reduced in the transverse direction. Nevertheless, the invention is applicable to any multirotor vehicle of arbitrary weight, such as a light drone to a large tonnage vehicle.