WO2019211875A1

WO2019211875A1 - Hybrid vertical takeoff and landing (vtol) aircraft with vehicle assist

Info

Publication number: WO2019211875A1
Application number: PCT/IN2019/050354
Authority: WO
Inventors: Alvin ANTHONY
Original assignee: Anthony Alvin
Priority date: 2018-05-04
Filing date: 2019-05-02
Publication date: 2019-11-07

Abstract

The present invention provides an energy efficient VTOL aircraft capable of flying like helicopter as well as fixed wing airplane based on requirement. The propulsion for the aircraft is either all electric or hybrid/electric. The aircraft comprises vertical and tilting rotors. Each rotor system comprises a compact high power to weight ratio electric motor and an optimized propeller either for cruise or hover depending upon the function. The usage of electric motors for propulsion reduces the noise significantly as compared with traditional aircraft engines and is less complex to design and manufacture. The aircraft also covers a fully autonomous VTOL assist vehicle capable of assisting main aircraft vehicle in vertical take-off and hence reducing energy consumption for main aircraft during vertical take-off, landing and hover. The autonomous vehicle is configured for detaching itself from main vehicle once main vehicle transitions to forward flight to operate like a fixed wing airplane.

Description

HYBRID VERTICAL TAKEOFF AND LANDING (VTOL) AIRCRAFT WITH VEHICLE

ASSIST

TECHNICAL FIELD

[1] The present disclosure relates generally to a vertical take-off and landing (VTOL) aircraft using a hybrid-electric propulsion system. The present invention is particularly related to a hybrid VTOL aircraft with a combination of vertical rotors and tilt rotors enabling hovering and horizontal flight.

BACKGROUND

[2] Aircrafts having vertical or steep take-off and landing capabilities are well known in the art. Some of the common types of VTOL aircrafts are Helicopters (rotary wing aircraft), wing tip mounted Tilt rotor aircrafts, thrust vector VTOL airplanes, Tilt wing aircrafts, and multicopter type of aircrafts with fixed vertical lift-off rotors or ducted fans. Helicopters usually comprise a large rotor system which is complex involving several mechanical parts for transmission or gearbox. The same rotor blade of the helicopter needs to perform dual function of vertical flight and forward flight. To fly the helicopter the pilot needs to use collective and cyclic control which incorporates complex mechanical systems and requires heavy maintenance. These complex mechanical parts have single points of failure and hence lack redundancy and are less efficient compared to fixed wing airplanes. Further, helicopters are extremely noisy and are less fuel efficient.

[3] The wing tip mounted tilt rotor VTOL aircrafts combine the efficiency of fixed wing airplane and helicopter. The wingtip mounted turbo shaft engines are connected via a common central gearbox so that a single engine powers both rotors in case of an engine failure. This leads to a complex mechanical system design. Also, the tilt mechanism of the wing tip mounted engines leads to increased complexity and maintenance. Also tilt rotor VTOL aircrafts are less energy efficient compared to their equivalent fixed wing counterparts.

[4] Moreover, Tilt wing VTOL aircrafts have engines mounted on the wing instead of the wing tip. These aircrafts still possess greater design complexity of the wing tilting mechanism due to heavy engines and hence are less energy efficient. Additionally, these aircrafts comprise several single points of failure when compared to a fixed wing airplane.

[5] Multicopter types of aircrafts have multiple redundancies when compared to the above discussed aircrafts.

[6] US patent application, US20140151495 discloses an electrically powered vertical takeoff and landing aircraft with one or more rotors. However, the rotors are used for only hovering effect. The prior arts does not teach a combination of vertical rotors and tilt rotors.

[7] Hence there is a need for providing an energy efficient VTOL aircraft capable of flying like helicopter as well as fixed wing airplane based on requirement. There is also a need for an all electric or hybrid/electric VTOL landing aircraft with fixed vertical rotors and wing mounted tilting rotors for forward flight with a smooth and quiet operation. Further, there is a need for providing a VTOL aircraft that comprising of specially arranged tilting rotors and fixed rotors allowing the aircraft to hover, vertically take-off and land like a helicopter and climb, cruise and descent like a fixed wing airplane.

[8] The above-mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.

SUMMARY

[9] The primary object of the present invention is to provide an energy efficient VTOL aircraft capable of flying like helicopter as well as fixed wing airplane based on the requirement. Another object of the present invention is to provide an all electric or hybrid/electric VTOL - aircraft with fixed vertical rotors and wing mounted tilting rotors for forward flight with a smooth and quiet operation. The VTOL aircraft comprises specially arranged tilting rotors and fixed rotors allowing the aircraft to hover, vertically take-off and land like a helicopter and climb, cruise and descent like a fixed wing airplane. The VTOL aircraft with electric propulsion allows the aircraft to have less number of complex mechanical systems and least possible maintenance. Yet another object of the present invention is to provide a VTOL aircraft comprising a compact high power to weight ratio electric motor for each rotor system and an optimized propeller either for cruise or hover depending upon the function. Yet another object of the present invention is to provide a VTOL aircraft that uses electric motors for propulsion for significantly reducing the noise as compared with traditional aircraft engines and is less complex to design and manufacture. Yet another object of the present invention is to provide a VTOL aircraft comprising a fully autonomous VTOL assist vehicle for assisting a main aircraft vehicle in vertical take-off and hence reducing the energy consumption for the main aircraft vehicle during vertical take-off, landing and hover. Yet another object of the present invention is to provide an autonomous VTOL aircraft that detaches itself from the main vehicle once the main vehicle transitions to forward flight in order to operate like a fixed wing airplane. Yet another object of the present invention is to provide a VTOL aircraft that is suitable for use in both manned and unmanned applications with different payload and passenger capabilities.

[10] According to an embodiment of the present invention, a hybrid vertical take-off and landing aircraft is disclosed. The aircraft comprises an engine configured to operate on an electric mode and a mechanical mode. The engine includes a pair of wings attached to a body of the aircraft to form a box wing architecture that provides improved aerodynamic efficiency, where the wings comprise an anterior portion attached to a nose of the aircraft body and a posterior portion attached to a tail of the aircraft body. The aircraft includes a rotor system with a plurality of vertical rotors and a pair of tilting rotors. The plurality of vertical rotors is attached to the pair of wings to provide upward thrust. The pair of tilting rotors are attached to the posterior portion of the wings to provide forward thrust for horizontal flight. The aircraft includes a flight system computer that is coupled to the engine and adapted to control the power supplied to the plurality of vertical rotors and the pair of tilting rotors during vertical take-off and horizontal flight, the flight system computer is also configured to select operation of the engine in at least one of electric mode, mechanical mode or a combination thereof. [11] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[12] The other objects, features, and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

[13] FIG. 1 illustrates a perspective view of the main aircraft vehicle in vertical flight configuration, according to an embodiment of the present invention.

[14] FIG. 2 illustrates aperspective side view of the main aircraft vehicle in vertical flight configuration, according to an embodiment of the present invention.

[15] FIG. 3 illustrates aperspective top view of the aircraft in the vertical fight configuration, according to an embodiment of the present invention.

[16] FIG. 4 illustrates aperspective front view of the aircraft in the vertical flight configuration, according to an embodiment of the present invention.

[17] FIG. 5 illustrates a perspective view of the main aircraft vehicle showing the tilting rotors, according to an embodiment herein.

[18] FIG. 6 illustrates a perspective view of the main aircraft vehicle with tilting rotors tilted horizontally for the horizontal fight configuration, according to an embodiment herein.

[19] FIG. 7 illustrates a perspective view of the main aircraft vehicle in the horizontal flight configuration with the landing gears retracted, according to an embodiment herein.

[20] FIG. 8 illustrates a perspective side view of the main aircraft vehicle in the horizontal flight configuration with the landing gear retracted, according to an embodiment herein.

[21] FIG. 9 illustrates a schematic diagram depicting a process of aircraft taking-off vertically from the ground and transitioning to forward flight, according to an embodiment herein.

[22] FIG. 10 illustrates a perspective view of a multicopter VTOF assist vehicle, according to an embodiment herein.

[23] FIG. 11 illustrates a perspective side view of the multicopter VTOF assist vehicle, according to an embodiment herein. [24] FIG. 12 illustrates a perspective top view of the multicopter VTOL assist vehicle, according to an embodiment herein.

[25] FIG. 13 illustrates a perspective view of the main aircraft vehicle mounted to the multicopter VTOL assist vehicle, according to an embodiment herein.

[26] FIG. 14 illustrates a perspective side view of the main aircraft vehicle mounted on the multicopter VTOL assist vehicle, according to an embodiment herein.

[27] FIG. 15 illustrates a schematic diagram depicting a process of aircraft taking-off vertically with the help of multicopter VTOL assist vehicle and transitioning to forward flight, according to an embodiment herein.

[28] FIG. 16A illustrates a block diagram of a flight controller system in the aircraft, according to an embodiment herein.

[29] FIG. 16B illustrates a block diagram of a sensor unit present in the flight controller system.

[30] Although the specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[31] In the following detailed description, a reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.

[32] The various embodiments of the present invention provide an energy efficient VTOL aircraft capable of flying like helicopter as well as fixed wing airplane based on requirement. The propulsion for the aircraft is either all electric or hybrid/electric. The aircraft is safe, reliable, redundant and quiet in operation. Electric propulsion allows the aircraft to have less number of complex mechanical systems and least possible maintenance. Each rotor system comprises a compact high power to weight ratio electric motor and an optimized propeller either for cruise or hover depending upon the function. The usage of electric motors for propulsion reduces the noise significantly as compared with traditional aircraft engines and is less complex to design and manufacture. The aircraft also covers a fully autonomous VTOL assist vehicle capable of assisting the main aircraft vehicle in vertical take-off and hence reducing the energy consumption for the main aircraft vehicle during vertical take-off, landing and hover. The autonomous vehicle is configured for detaching itself from the main vehicle once the main vehicle transition to forward flight to operate like a fixed wing airplane.

[33] According to one embodiment of the present invention, the VTOL landing aircraft comprises one or more fixed vertical rotors and wing mounted tilting rotors for forward flight with a smooth and quiet operation. The one or more fixed vertical rotors are mounted on the wing using a mount. The one or more tilting rotors are mounted onto the rear wing with a mount. The rotor system comprises an electric motor and an optimized propeller for the specific operation.

[34] According to an embodiment of the present invention, during transition from vertical flight to forward flight, the tilting rotors tilt to an angle until the aircraft/airplane achieves a certain forward speed at which the aircraft wings produce enough lift to keep the aircraft airborne during the forward flight. Once sufficient forward speed is achieved and the aircraft starts to cruise then the vertical thrust rotors switch off and the forward flight is powered by the tilting rotors which tilt horizontally.

[35] FIG. 1 illustrates a perspective view of the main aircraft vehicle in vertical flight configuration, according to an embodiment of the present invention. With respect to FIG. 1, the aircraft is shown in the vertical flight configuration. The aircraft comprises the fuselage 102; the forward wing 104 and the rear wing 106, the set of fixed vertical rotors l08-a to l08-j and the set of tilting rotors 110 for forward flight. Fuselage l02comprises the cockpit area 112; the nose landing gear 114; the set of main landing gears 202withthe wings 104 and 106 attached. The aircraft further comprises one or more batteries, avionics and flight control computers (not shown). The aircraft is configured for carrying a plurality of passenger’s/payload cabin in the fuselage 102. The wings 104 and l06comprise one or more batteries and controllers for the electric motors. The set of fixed vertical rotors l08-a to l08-j are mounted onto the wings 104 and 106 using the mount 118. The tilting rotors 110 are mounted onto the rear wing l06using another mount 116. The rotor systems l08-a to l08-j and 110 comprise an electric motor and an optimized propeller (not shown) for the specific operation. According to one embodiment of the present invention, vertical thrust for the aircraft is provided by the set of fixed rotors l08-a to l08-j either in planar or non-planar orientations. Forward thrust is provided by the set of tilting rotors 110 which comprises tilting actuators (not shown) to tilt the rotors from vertical position to horizontal position during forward flight. The non-planar orientation of the vertical set of rotors l08-a to l08-j also provide lateral and directional control adjustments during the VTOL mode. According to one embodiment of the present invention, the set of tilting rotors 110 are also configured for assisting in the vertical take-off and landing or hover flight phases. The tilting rotors 110 are also operational during the vertical take-off and landing mode and hence contribute to the component of vertical thrust.

[36] FIG. 2 illustrates a perspective side view of the main aircraft vehicle in vertical flight configuration, according to an embodiment of the present invention. With respect to FIG. 2, the various part of main aircraft such as the fuselage 102, vertical rotors 108, tilting rotors 110, main landing gear 116, secondary landing gear 202 are shown. In accordance with an embodiment, the aircraft has 10 or more number of rotors for the VTOL operations. This enables higher redundancy in case of one or two motor failures. The motor power and thrust is sized such a way that in the event of even three VTOL motors failed and other motors will be able to safely land the airplane back

[37] FIG. 3 illustrates a perspective top view of the aircraft in the vertical fight configuration, according to an embodiment of the present invention. With respect to FIG. 3, all the vertical rotors l08-a to l08-j are shown which extends on the pair of wings. The pair of wings form a box wing architecture that provides improved aerodynamic efficiency. The box wing architecture also provides structural rigidity and reduction in structural weight over the conventional aircraft layout.

[38]

[39] With respect to FIG. 4, the tilting rotors 110 and the cockpit area 112 is shown. FIG. 5 illustrates a perspective view of the main aircraft vehicle showing the tilting rotors, according to an embodiment herein. FIG. 5 illustrates the tilting rotors 110 attached using a mount to the rear end. FIG. 6 illustrates a perspective view of the main aircraft vehicle with tilting rotors tilted horizontally for the horizontal fight configuration, according to an embodiment herein. With respect to FIG. 6, the aircraft moving in forward flight axis and the landing gears 116 is shown. FIG. 7 illustrates a perspective view of the main aircraft vehicle in the horizontal flight configuration with the landing gears retracted, according to an embodiment herein. With respect to FIG. 7, the landing gears 116 in retracted position is shown.

[40] FIG. 8 illustrates a perspective side view of the main aircraft vehicle in the horizontal flight configuration with the landing gear retracted, according to an embodiment herein. With respect to FIG. 8, the side view of the main aircraft moving in forward flight axis is shown.

[41] FIG. 9 illustrates a schematic diagram depicting a process of aircraft taking -off vertically from the ground and transitioning to forward flight, according to an embodiment herein. With respect to FIG. 9, during the transition from vertical flight to forward flight the tilting set of rotors tilt to an angle until the airplane achieves a certain forward speed at which the aircraft wings produce enough lift to keep the aircraft airborne during the forward flight. Once sufficient forward speed is achieved and the aircraft starts to cruise then the vertical thrust rotors 108 switch off and the forward flight is powered by the tilting rotors 110 which tilt horizontally. The various positions of the main aircraft in the take-off process are depicted using reference numerals 902 to 910.

[42] According to one embodiment of the present invention, the vertical lift propellers (part of 108) are designed aerodynamically and optimized to perform efficiently for the VTOL modes like hover, vertical take-off and landing. The tilting propellers (part of 110) are optimized to perform efficiently in cruise. Both kinds of propeller design are also noise optimized providing quieter flight operations when flying over urban environment.

[43] According to one embodiment of the present invention, due to multiple number of rotor systems 108 for VTOL operations the aircraft is redundant in case of a single rotor failure providing a greater redundancy and overall safety. Similarly, multiple rotor systems 110 for the forward flight allow the aircraft to safely perform its operations in case of a single rotor system failure.

[44] According to one embodiment of the present invention, rechargeable batteries (not shown) are used as the energy source in the all-electric version of the aircraft to power the motors and the subsystems required for the smooth operation of the aircraft. In the hybrid/electric version of the aircraft the electric motors are powered by the reciprocating engine generator set (not shown) which is onboard the vehicle and at the same time incorporates batteries which are charged by the generator system. In one example embodiment, hydrogen fuel is used to power a fuel cell to generate electricity for powering the electric motor. The source of hydrogen is stored in a pressurized tank which can power the fuel cell for extended range and endurance. In one example embodiment, fossil fuels like gasoline, diesel or AV gas are used to power the reciprocating engine. The advantage provided by the hybrid/electric system is extended range and flight endurance and onboard battery charging.

[45] According to one embodiment of the present invention, each rotor system 108 and 110 operates independently. The distributed electric propulsion puts lesser load on the single rotor system. In case of single rotor failure, the load is distributed on other motors and the control response is faster in case of gusts and unexpected pilot actions.

[46] According to one embodiment of the present invention, robust and redundant flight control systems are used to achieve the flight during VTOL and fixed wing mode of flights. In one example embodiment, three independent flight control computers (not shown) are used for redundancy and an independent backup flight control computer is used which takes over with limited protections to safely land the aircraft in case the three independent flight control computers fail. The onboard flight control computers also let the airplane perform VTOL to transition automatically without much pilot inputs and efforts.

[47] In another example embodiment, following control and sensing mechanisms are incorporated to ensure a safe operation flight (not shown): · Hardware Failure: 1. Failure of Motor-prop Combination a) Determine the RPM of each motor using sensors b) Identify deficit, if any with respect to Commanded value c) Increase RPM in opposite side till wings level 2. Battery Fail safe 17 a) Use of Aural/Visual Warnings to identify deficiency in Power available in Batteries, or single cell failures. 3. Failure in Tilting Mechanisms a) Usage of sensors to track the orientation of Motor-hub (Motor -propeller longitudinal axis) 4. Redundant Aircraft Sensors and Flight Control Systems a) Power also to be derived from more than one Battery source to maintain redundancy 5. Full aircraft Parachute/Landing Air-Bags (not shown) · In-Flight Protections: 1. Angle of Attack: Alfa > Limit maximum angle of attack: Increase RPM 0 Increase in velocity 0 Decrease Alfa 2. Velocity Velocity < Stall Velocity: Increase RPM 0 Increase in velocity 0 Decrease Alfa 3. Roll (Phi) Phi > Limit bank angle: Increase RPM in opposite direction OWings level

[48] According to one embodiment of the present invention, high aerodynamic efficiency and lesser energy consumption in horizontal flight is achieved by the box wing design or closed/joined wing design which diminishes the effect of wing tip vortices. The box wing design provides greater structural strength as the front and rear wings are interconnected.

[49] FIG. 10 illustrates a perspective view of a fully autonomous multicopter VTOL assist vehicle, according to an embodiment herein. With respect to FIG. 10, the fully autonomous electric multicopter VTOL assist vehicle is shown. The multicopter vehicle includes a fuselage 1002; a set of ducted propeller systems 1006. The fuselage 1002 also comprises flight control computer, batteries, onboard sensing unit and navigation systems (not shown) and the main aircraft landing gear securing points 1004. The ducted fan or propeller system 1006 further comprises an electric motor and controllers in a housing 1106; a set of high lift propellers 1102 and guide vanes 1104 (as shown in FIG. 11).

[50] FIG. 12 illustrates a perspective top view of the multicopter VTOL assist vehicle, according to an embodiment herein.

[51] FIG. 13 illustrates a perspective view of the main aircraft vehicle mounted to the multicopter VTOL assist vehicle, according to an embodiment herein. FIG. 14 illustrates a perspective side view of the main aircraft vehicle mounted on the multicopter VTOL assist vehicle, according to an embodiment herein. FIG. 15 illustrates a schematic diagram depicting a process of aircraft taking-off vertically with the help of multicopter VTOL assist vehicle and transitioning to forward flight, according to an embodiment herein. According to one embodiment of the present invention, a fully autonomous electric multicopter VTOL assist vehicle lOOOis also useful in assisting the main aircraft 100 to hover, vertically take-off and land. This arrangement significantly puts lesser load on the main vehicle 100 during these modes of flight. Once the main aircraft 100 transits to the forward flight the VTOL assist vehicle 1000 detaches itself automatically and returns back to the base as shown in FIG. 15. This reduces the battery or energy consumption during hover or VTOL operations where the power consumption is greater when compared to horizontal flight modes. This vehicle also flies from the base station and reattaches itself to the approaching main aircraft to the base in order to assist in the vertical descent and landing thus putting less load on the motors and batteries of the main aircraft 100.

[52] FIG. 16A illustrates a block diagram of a flight controller system in the aircraft. The flight controller system comprises a battery unit 162, an invertor 164, a flight control computer 166, a generator 168, and a rotor system. The flight controller system provides flexibility in the number and position of electric rotors. The flight controller system can drive a plurality of rotor system 1 to N in a distributed configuration. The battery 162 is a rechargeable and replaceable battery that can easily be swapped at heliports. The battery 162 reduces noise during take-off and hover and enables the aircraft to operate in silent mode. The controller 166 can select the operation of the aircraft in electric mode, mechanical mode or a combination of both. The invertor 164 receives power from the battery to drive the rotor system. The invertor 164 also receives power from the generator operated by a turbo shaft. The turbo shaft is operated by volatile fuels such as liquid hydrogen. The generator converts mechanical energy to electricity for transmission and distribution. The generator, battery unit and the

[53] The flight controller system can selectively provide power to at least one of the rotor system during vertical flight and horizontal flight. The rotor system includes a propeller and an electric motor. The rotor system is pivotally attached to the aircraft body by a mounting boom or rod. The pair of tilting rotors includes propellers aligned at an angle to the horizontal pivotal axis of the wings. The pair of tilting rotors is configured to transition the movement of aircraft from vertical flight to horizontal flight the plurality of vertical rotors is configured to produce a thrust force to counter the weight of the aircraft to achieve vertical take-off.

[54] The system avoids the need for complex mechanical connections between the propeller, the gas-turbine and the electric motors. The system also enables two-way current flow enabling in-flight recharge of batteries.

[55] According to an embodiment of the present invention, a hybrid vertical take-off and landing aircraft is disclosed. The aircraft comprises an engine configured to operate on an electric mode and a mechanical mode. The engine includes a pair of wings attached to a body of the aircraft to form a box wing architecture that provides improved aerodynamic efficiency, where the wings comprise an anterior portion attached to a nose of the aircraft body and a posterior portion attached to a tail of the aircraft body. The aircraft includes a rotor system with a plurality of vertical rotors and a pair of tilting rotors. The plurality of vertical rotors is attached to the pair of wings to provide upward thrust. The pair of tilting rotors are attached to the posterior portion of the wings to provide forward thrust for horizontal flight. The aircraft includes a flight system computer that is coupled to the engine and adapted to control the power supplied to the plurality of vertical rotors and the pair of tilting rotors during vertical take-off and horizontal flight, the flight system computer is also configured to select operation of the engine in at least one of electric mode, mechanical mode or a combination thereof. The aircraft is manually operated or completely autonomous. The aircraft is manufactured of Carbon fiber composite, glass fiber composite, aluminum and steel. The aircraft also comprises a plurality of control surface actuators operated by the flight system computer.

[56] The flight controller system is coupled to a sensor unit that monitor the parameters and performance of the aircraft and transmit feedback signals to the flight controller system. The feedback signals determine the action of the flight controller system in case of an autonomous mode or manual mode. The components of the sensor unit is shown in FIG. 16B. The sensor unit includes a motion sensor, control surface actuator feedback sensors, rotor system sensor and battery management sensors. The flight system computer is driven by flight envelope and flight control law in an autonomous mode. The flight envelope limits the airplane from high speed, tilt and turn. The Flight control law is maintained by measuring the feedback from the sensor unit to generate an output , and further applying the output to drive the aircraft

[57] The motion sensors include gravity sensor, linear acceleration sensor, a rotation vector sensor. The sensor unit may include a gyroscope. The motion sensors also monitor the aircraft speed and accelerations, pitch, roll, yaw & angular rates. The rotor system sensors provide rotation per minute (rpm, direction, angle, and power. The control surface actuator feedback sensors provide information about the angle of the aircraft, force, and linear travel distance. The battery management sensors provide information about the voltage, current, temperature, humidity, and battery charging status.

[58] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.

[59] It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modifications. ADVANTAGESOF THE INVENTION

[60] The various embodiments of the present invention provide an energy efficient VTOL aircraft capable of flying like helicopter as well as fixed wing airplane based on requirement. The novel aircraft offers an efficient design with less energy consumption during flight due to the joined wing (box wing) configuration. This reduces the wingtip induced vortices and less induced drag. Lesser drag leads to less energy consumption. The aircraft uses high power to weight ratio electric motor for driving the propellers. The electric motors have less number of rotating parts and thus reduced complexity. Electric motors are quieter in operation when compared to reciprocating or jet engines. Electric motors are controlled digitally as compared to mechanical engines.

[61] Also, vertical set of fixed rotors are used in the aircraft for performing hover, vertical take-off and landing. A set of tilting vertical rotors is used for forward flight. Thus, the aircraft has robust flight control architecture for a safe and reliable flight. Multiple flight control computers are used for redundancy. The electric propulsion brings down the operational cost of the vehicle. The cost of operation for the aircraft is approximately 6 times lesser than the fuel based aerial vehicles. Further, the vertical take-off and landing allows the airplane to take-off and land from small spaces such as top of a building, helipads etc. No new infrastructure is needed for the operations. Adding the capability of fixed wing airplane makes it cruise efficiently for longer distances and flight time as compared to helicopters available in recent times. The maintenance cost of the aircraft is low as the numbers of parts are less when compared to other available helicopters and airplanes. As the aircraft does not use hydraulic system, fuel system or pneumatic system, the engine architecture is less complex. The aircraft is suitable for use in commercial applications such as Urban Air taxi services, Intercity charter services, personal transportation aircraft, Cargo transportation, Flying school training aircraft, Surveillance aircraft, Unmanned Aerial systems, ferry services, Air ambulance systems etc. This present invention facilitates people around the world to commute faster than a car from one location to another at the similar cost of a taxi bypassing all the traffic on the ground. The cost of operation is less since the airplane operates on electricity as compared to aircraft fuel.

[62] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such as specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.

[63] It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modifications. However, all such modifications are deemed to be within the scope of the claims.

Claims

CLAIMS What we claimed is:

1. A hybrid vertical take-off and landing aircraft comprising: an generator configured to produce electric power using power supplied by an engine; a pair of wings attached to a body of the aircraft to form a box wing architecture that provides improved aerodynamic efficiency, where the wings comprise an anterior portion attached to a nose of the aircraft body and a posterior portion attached to a tail of the aircraft body; a rotor system configured to operate on an electric mode and a mechanical mode, the rotor system comprising: a plurality of vertical rotors attached to the pair of wings to provide upward thrust; a pair of tilting rotors attached to the posterior portion of the wings to provide forward thrust for horizontal flight; and a flight system computer coupled to the engine and adapted to control the power supplied to the plurality of vertical rotors and the pair of tilting rotors during vertical take-off and horizontal flight, the flight system computer is also configured to select operation of the engine in at least one of electric mode, mechanical mode or a combination thereof.

2. The hybrid vertical take-off and landing aircraft as claimed in claim 1, comprises a battery unit that provides electric power to operate the rotor system in electric mode.

3. The hybrid vertical take-off and landing aircraft as claimed in claim 2, wherein the battery is a replaceable battery.

4. The hybrid vertical take-off and landing aircraft as claimed in claim 1, wherein the mechanical mode comprises operating the rotor system by a generator powered by combustible fuels.

5. The hybrid vertical take-off and landing aircraft as claimed in claim 1, wherein the improved aerodynamic efficiency results in reduced fuel consumption, and static stability and control.

6. The hybrid vertical take-off and landing aircraft as claimed in claim 1 , wherein the rotor system is pivotally attached to the aircraft body by a mounting boom.

7. The hybrid vertical take-off and landing aircraft as claimed in claim 1, wherein the pair of tilting rotors includes propellers aligned at an angle to the horizontal pivotal axis of the wings.

8. The hybrid vertical take-off and landing aircraft as claimed in claim 7, wherein the pair of tilting rotors is configured to transition the movement of aircraft from vertical flight to horizontal flight.

9. The hybrid vertical take-off and landing aircraft as claimed in claim 1, wherein the plurality of vertical rotors is configured to produce a thrust force to counter the weight of the aircraft to achieve vertical take-off.

10. The hybrid vertical take-off and landing aircraft as claimed in claim 1 is manually operated or completely autonomous.

11. The hybrid vertical take-off and landing aircraft as claimed in claim 1 is composed of Carbon fiber composite, glass fiber composite, aluminum and steel.

12. The hybrid vertical take-off and landing aircraft as claimed in claim 1 comprises a plurality of control surface actuators operated by the flight system computer.

13. The hybrid vertical take-off and landing aircraft as claimed in claim 1, wherein the flight system computer is coupled to a sensor unit comprising motion sensors, control surface actuator feedback sensors, rotor system sensor and battery management sensors.

14. The hybrid vertical take-off and landing aircraft as claimed in claim 1, wherein the flight system computer is driven by flight envelope and flight control law in an autonomous mode.

15. A hybrid vertical take-off and landing aircraft system comprising: an aircraft body comprising: an engine configured to operate on an electric mode and a mechanical mode; a pair of wings attached to a body of the aircraft to form a box wing architecture that provides improved aerodynamic efficiency, where the wings comprise an anterior portion attached to a nose of the aircraft body and a posterior portion attached to a tail of the aircraft body; a rotor system comprising: a plurality of vertical rotors attached to the pair of wings to provide upward thrust; a pair of tilting rotors attached to the posterior portion of the wings to provide forward thrust for horizontal flight; a controller coupled to the engine and adapted to control the power supplied to the plurality of vertical rotors and the pair of tilting rotors during take-off and horizontal flight, the controller is also configured to select operation of the engine in at least one of electric mode, mechanical mode or a combination thereof; an aircraft vehicle assist that is coupled to the aircraft body during hovering and take-off, the vehicle assist comprising: a body with a plurality of vertical rotors attached thereto in a planar formation; a sensory unit coupled to the body and configured to identify the aircraft body location and attaches to the aircraft body during landing; and a controller unit coupled to the sensory unit and configured to transmit signals that cause the body to attach or detach to the aircraft body.