Patent Application
20240253778
The disclosed invention relates to an aerial vehicle with both VTOL (vertical take-off and landing) and fixed wing flight capability. More specifically to the configuration of the box aerostructure with multiple proprotors and lift rotors.
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 a plurality of airfoiled blades in rotation to generate to thrust by moving air. The rotary wing is commonly referred as “rotor”. A rotor positioned in the center of a shroud is called “ducted fan” or “ducted rotor”. In general, a rotor comprising of a plurality of blades rotating on the same axis. The rotor generates thrust to allow 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 heavily in the global urban area, an affordable electrical VTOL vehicle is a 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.
The arrival of distributed electrical propulsion system and advanced energy storage allows modern VTOL multirotor vehicle to substitute the traditional helicopter. The VTOL multirotor rotorcraft is advantageous for its safety redundancy, in comparison to a single large rotor helicopter. The electrical propulsion system contains multiple independent smaller rotors to provide lift, propulsion and steering control. Quad-rotorcraft is a popular design for electrical multirotor vehicle, a simple design comprises of four rotors equally spaced apart. The fixed pitch smaller rotor 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 rotors creates a thrust vector for lift, propulsion and steering control. The disadvantage of the four rotors propulsion is that the rotor is smaller in diameter. Based on the momentum theory, small diameter rotor has low thrust lift efficient, due to the high disc loading.
Advantageously, modern electrical VTOL vehicle also has the capability to transition to airplane mode for forward flight. The energy required for VTOL flight is significantly higher than the energy required for a fix wing airplane flight to maintain forward flight. The VTOL vehicle can experience the following three types of flight mode: thrust borne, partial wing borne and wing borne flight. The vehicle is thrust borne in VTOL flight, which means the flight is made possible by vertical rotor thrust. Partial borne means the flight is made possible by the combination of vertical rotor thrust and wing lift. The vehicle is wing borne in airplane flight, which means above a certain forward speed, the flight is made possible by lift generated by the wing. Furthermore, the forward propulsive movement in the airplane mode is generated by at least one tiltable proprotor. The main challenge of the transitional capability is the rapid hand over from thrust borne flight to wing borne flight. The common design with proprotors mounted on the fixed wing lacks of partial wing borne flight capability. The desirable solution is to design the vehicle with partial wing borne flight capability between the transition of thrust borne flight to wing borne flight. Moreover, some modern VTOL design is highly complex with multiple independent actuations to transition between VTOL flight and airplane flight, which leads to the shortfall of unsymmetrical wing lift. Therefore, the desirable solution is to design a VTOL vehicle with a single actuation to transition between VTOL flight and airplane flight.
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 aerostructure design is introduced to improve lift efficiency.
In one embodiment of the invention of a multirotor vehicle with both VTOL and airplane flight capability is provided, comprising a fuselage having a longitudinal axis, a tail boom, a pair of fixed wings, a pair of rotor booms in the VTOL flight configuration, a pylon coupled to the fixed wings and rotor booms, a plurality of proprotors coupled to the rotor booms, a plurality of lift rotors coupled to the tail boom, a pair of vertical and horizontal stabilizer, a pair of ailerons, a pair of rudders, a pair of elevators, and a pair of jet nozzles. Also in one embodiment the pair of rotor booms in the airplane flight configuration.
In another embodiment of the invention of a multirotor vehicle with both VTOL and airplane flight capability is provided, comprising a fuselage having a longitudinal axis, a tail fin, a pair of fixed wings, a pair of rotor booms in the VTOL flight configuration, a pylon coupled to the fixed wings and rotor booms, a plurality of ducted proprotors coupled to the rotor booms, a plurality of ducted lift rotors coupled to the tail boom, a pair of vertical and horizontal stabilizer, a pair of ailerons, a pair of rudders, a pair of elevators, and a pair of jet nozzles. Also in one embodiment the pair of rotor booms in the airplane flight configuration.
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 or rotation is shown in hollow arrow and force vector is shown in solid arrow.
Advantageously, VTOL (vertical take-off and landing) vehicle can operate without a long runway. However, VTOL flight 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 vehicle is commonly designed with electrical power plant. In order to reduce the weight of electrical energy storage, an efficient VTOL vehicle can convert to airplane configuration 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”. Moreover, the technical term “proprotor” is referred as the rotary wing capable of operating both as an airplane-style propeller and helicopter-style rotor. Moreover, the term “symmetric” is used to describe a component, feature, or element which is symmetrical with respecting to median plane of the rotorcraft. It is further understood that the terms “includes”, “including”, “comprises”, “comprising”, “couples”, ‘coupled”, “mounts”, and “mounted”, when used herein, specify the presence of stated features, components and elements, without the further detail on the method of mechanical interconnexion. In addition, it is also understood that the singularity form “a”, “an”, and “the” used throughout the description are intended to includes plural forms as well, unless the context clearly specifies otherwise.
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The multirotor aerial vehicle in VTOL configuration from embodiment 100 in different flight configurations is shown in
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Naturally, there are numerous variations, modifications and alternative 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 a multirotor aerial vehicle with specific positioning of the forward tiltable rotors and rear fixed rotors secured to the vehicle. Contrary to a handful examples of multirotor VTOL vehicle design, this invention has either tiltable rotor nor lift rotors coupled to the wing. The absence of disruption by nacelle and rotor propwash over the clean wing is beneficial for decreasing noise and improving lift performance. Moreover, the lift characteristic of the clean wing has minimized impact by rotor propwash during transition between thrust born flight and wing born flight. The tiltable rotor can be achieved by tiltable boom, tiltable nacelle pod or tiltable rotor hub. In addition, the single actuation of the rotor booms allows to convert between thrust borne flight and wing borne flight. The distal end of the rotor boom is mechanical coupled to the distal end of the wing to create the box aerostructure is an option. The box aerostructure benefits from an improvement of structural strength, fatigue strength and load carrying strength. Nevertheless, the invention is applicable to any multirotor vehicle of arbitrary weight, such as a light drone to a large tonnage vehicle.
