Aerial maneuvering vehicle and method of operating the same

Abstract

An aerial vehicle and method of operating the same, wherein an engine is operated on demand to provide mechanical drive power or electrical power. A battery is charged with electrical power from the engine. A main rotor is operated using electrical power from the battery and electrical power generated by the engine to perform takeoff, landing, and cruising. An auxiliary rotor is disposed at or adjacent to a center of gravity of a vehicle body and is mechanically connected to the engine via a clutch. When the clutch is in an engaged position, the auxiliary rotor performs takeoff, landing, or cruising by receiving mechanical drive power from the engine. A controller monitors a state of the battery and the main rotor and controls operation of the engine and the clutch.

Description

TECHNICAL FIELD

[0001] The present application relates generally to an air mobile vehicle. BACKGROUND

[0002] Related art methods using fans and impellers as lifting devices have been proposed for fixed-wing vertical take-off and landing (VTOL) aircraft, small personal air vehicles (PAVs), etc. that are capable of operating at higher speeds than helicopters. However, when such fan-based lifting devices designed for such VTOL aircraft or PAVs are used for urban air mobility (UAM) vehicles, the following problems can occur: 1) flight efficiency is low because a large amount of electric power is consumed during generation of lift; 2) in the case of air mobile vehicles for carrying passengers, the passenger space can be reduced because the fan used as the main propulsion device needs to occupy a large amount of space to generate propulsion force; and 3) when the fan is used as the main propulsion device, performance and flight reliability can be significantly reduced due to inlet flow separation, etc. during forward mobility due to the characteristics of the fan.

[0003] Therefore, the application of such fan-based propulsion devices of the related art for UAM vehicles is limited, and in the application of the propulsion device, the passenger space and power consumption need to be considered to determine the layout and installation plan.

[0004] In the mobility of the UAM vehicle, the vertical take-off and landing mobility of the rotor is a factor of high accident rate, and therefore must be highly prioritized to provide high reliability. The auxiliary propulsion device is a device that provides safety to the air mobile vehicle in an emergency situation such as rotor failure or distributed electric propulsion system failure during vertical take-off or landing operation. In the UAM vehicle in which the number of passengers is relatively small, in most cases, the center of gravity of the vehicle body is located at the cabin position. However, when the auxiliary propulsion device is installed at the position of the cabin, the available space of the cabin can be reduced, and the drag applied to the belly of the UAM vehicle can increase, which is problematic.

[0005] The foregoing is merely intended to assist in the understanding of the background of the present application, and is not meant to be the scope of the related art known to those skilled in the art. SUMMARY

[0006] Accordingly, the present application has been made keeping in view the above-mentioned problems occurring in the prior art. The detailed description of the present application provides an air mobile vehicle capable of performing a vertical take-off and landing function and a cruising function. In an embodiment, the air mobile vehicle has a structure capable of reliably providing an auxiliary propulsion force, thereby improving safety of flight when a propulsion force of a main rotor is insufficient or at least one of the main rotors fails, and in particular, when at least one of the main rotors fails such that the propulsion force is unbalanced in a lateral direction, a responsive operation can be flexibly performed to balance the vehicle body.

[0007] According to an embodiment of the present application, an air mobile vehicle includes an engine operated as needed to provide a mechanical driving force or electric power, a battery configured to be charged with the electric power from the engine, a main rotor operated using the electric power of the battery and the electric power generated by the engine to perform take-off, landing, and cruising, an auxiliary rotor disposed at or adjacent to a center of gravity of a vehicle body and mechanically connected to the engine via a clutch, the auxiliary rotor performing take-off, landing, or cruising by receiving the mechanical driving force from the engine when the clutch is in an engaged position, and a controller monitoring states of the battery and the main rotor and controlling operations of the engine and the clutch.

[0008] The engine can be an internal combustion engine.

[0009] The battery can be disposed at a separate location, for example, a rear of a nacelle or collinear with a wing of the vehicle body, and the main rotor can be disposed in an equal number on left and right sides of the battery.

[0010] The auxiliary rotor can be disposed on left and right sides of the nacelle.

[0011] The auxiliary rotor can be disposed to coincide with the center of gravity of the vehicle body in a lateral direction while being located at a distance of 0.002 times a length of the vehicle body or less from the center of gravity of the vehicle body in a longitudinal direction.

[0012] The engine can be located between the auxiliary rotor and the battery. The engine can be provided with a driving shaft at a front portion thereof. Left and right extending portions of the split shaft can receive a driving force via the driving shaft. The auxiliary rotor can be rotated by the split shaft.

[0013] The auxiliary rotor can be oriented in a vertical direction to provide an auxiliary propulsion force in a downward direction, thereby assisting in lifting the vehicle body.

[0014] The air mobile vehicle can further include a cover covering the auxiliary rotor. When the auxiliary rotor is driven, the cover can be slid such that the auxiliary rotor is exposed to the outside, so that the auxiliary rotor sucks in air from above and discharges the sucked air downward.

[0015] When the state of charge of the battery is low, the controller can charge the battery by operating the engine or support power supply to the main rotor. When the driving force of the main rotor is insufficient or the main rotor is malfunctioned, the auxiliary rotor can be driven by moving the clutch to the engaged position.

[0016] When the driving force of the main rotor is insufficient, the controller can generate equal auxiliary propulsion forces on the right side and the left side by opening both of the covers of the auxiliary rotor on the right side and the auxiliary rotor on the left side.

[0017] When one of the main rotors on the right side and the left side is malfunctioned, the controller can open one cover on the same side as the malfunctioned main rotor, thereby generating an auxiliary propulsion force on the side where the malfunction occurs.

[0018] Each auxiliary rotor can include an inlet and an outlet that generate an airflow. The auxiliary rotor can be rotatably coupled to the vehicle body. The direction of the outlet can change as the auxiliary rotor rotates.

[0019] The auxiliary rotor can include a centrifugal compressor type rotor that sucks in air in the direction of the rotor shaft and discharges air in the radial direction. The auxiliary rotor can be disposed such that the rotor shaft is directed toward the center of gravity of the vehicle body. The inlet can be disposed at a portion where the rotor shaft is disposed, such that the inlet is oriented in the same direction even when the auxiliary rotor rotates.

[0020] The outlet can be disposed in the radial direction of the auxiliary rotor, such that the auxiliary rotor assists in lifting propulsion or cruising propulsion in response to its rotation.

[0021] The vehicle body can include an air intake in the front portion thereof. The air intake can supply air to the inlets of the auxiliary rotors on both sides through an internal duct.

[0022] In the air mobile vehicle having a vertical take-off and landing function and a cruising function according to the embodiment of the present application, when the propulsion force of the main rotor is insufficient or at least one of the main rotors is malfunctioned, an auxiliary propulsion force can be reliably provided to improve the safety of flight. Specifically, even when one of the main rotors is malfunctioned such that the propulsion force is unbalanced or the lifting function or the cruising function is malfunctioned, a responsive operation can be flexibly performed to balance the vehicle body. BRIEF DESCRIPTION OF DRAWINGS

[0023] The above and other objects, features and other advantages of the present application will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0024] Figure 1 and Figure 2 is a conceptual view illustrating an air mobile vehicle according to an embodiment of the present application;

[0025] Figure 3is a view showing a supplementary rotor of an air mobile vehicle according to an embodiment of the present application; and

[0026] Figure 4 is a conceptual view showing an air mobile vehicle according to another embodiment of the present application. DETAILED DESCRIPTION

[0027] Figure 1 and Figure 2 is a conceptual view showing an air mobile vehicle according to an embodiment of the present application, Figure 3 is a view showing a supplementary rotor of an air mobile vehicle according to an embodiment of the present application, Figure 4 is a conceptual view showing an air mobile vehicle according to another embodiment of the present application.

[0028] Figure 1 and Figure 2 is a conceptual view showing an air mobile vehicle according to an embodiment of the present application. According to this embodiment, the air mobile vehicle includes an engine 100 operated as needed to provide mechanical driving force or electric power, a battery 500 configured to be charged with electric power from the engine 100, a main rotor 700 operated using electric power of the battery 500 and electric power generated by the engine 100 to perform takeoff, landing, and cruising, a supplementary rotor 300 disposed at or near a center of gravity of a vehicle body and mechanically connected to the engine 100 via a clutch 140, the supplementary rotor 300 performing takeoff, landing, or cruising by receiving mechanical driving force from the engine 100 when the clutch 140 is in an engaged position, and a controller monitoring states of the battery 500 and the main rotor 700 and controlling operations of the engine 100 and the clutch 140.

[0029] Embodiments of the present application apply a supplementary rotor separately from a main rotor to increase propulsion force or safely cope with a failure of the main rotor. Specifically, while the supplementary rotor is used, balance of a vehicle body can be appropriately maintained. In addition, a passenger space within a cabin can be reduced by a minimum amount, thereby providing a design in which an internal space can be advantageously obtained.

[0030] An air mobile vehicle with a fixed wing is a device designed for the purpose of achieving vertical takeoff and landing of an air mobile vehicle with a fixed wing, the maneuvering speed of which can be higher than that of an existing helicopter. A helicopter-type rotor exposed to the outside can have a higher risk of injury in the event of a collision. In the case of a ducted fan in which the rotor is enclosed inside a duct, there is a concern that the performance of the rotor will decrease due to separation of the inlet airflow, and the drag of the duct can increase significantly. Therefore, a small-sized, high-powered impeller with a blade screen is designed as a main lifting device and a power generation device. This method is designed to use the impeller to draw air through multiple inlets, combust the air drawn through multiple flow paths, and discharge the combustion gas through multiple outlets, thereby generating a propulsive force and power. In addition, for an air mobile vehicle for vertical takeoff and landing, a fan-based vertical takeoff and landing device is designed. Such a fan-based vertical takeoff and landing device can be provided with a wing so that a lift-drag ratio of 4 or more is obtained during cruising.

[0031] Embodiments of the present invention provide a layout and mounting structure of an auxiliary propulsion device for an air mobile vehicle having an engine-battery hybrid propulsion system. In the maneuvering of an air mobile vehicle, the maneuvering of vertical takeoff and landing of a rotor is the factor with the highest accident rate, and therefore must be highly prioritized to provide high reliability. The auxiliary propulsion device is a device that provides safety to an air mobile vehicle in an emergency situation, such as rotor failure or distributed electric propulsion system failure, during vertical takeoff or landing operation. When the auxiliary propulsion device is adjacent to the center of gravity of the air mobile vehicle, the auxiliary propulsion device can directly support the center of gravity, thereby achieving an effect similar to that of reducing the weight of the air mobile vehicle. Therefore, even in an emergency situation, when the entire moment of the main propulsion device (e.g., a rotor) applied to the air mobile vehicle can decrease, the presence of the auxiliary propulsion device can provide significantly higher reliability.

[0032] In embodiments of the present invention, as shown in Figure 1 and Figure 2 shown, in the case where the battery 500 is disposed at the rear of the vehicle body and the nacelle C is disposed at the front of the vehicle body, the center of gravity of the air mobile vehicle is set to be balanced in the longitudinal direction. Alternatively, the battery 500 can be disposed in line with the wing of the vehicle body. Furthermore, the engine 100 is disposed between the battery 500 and the nacelle C so that the center of gravity is balanced. Here, the engine 100 can be an internal combustion engine.

[0033] Further, the air mobile vehicle is designed such that the synthetic center of gravity of the vehicle body is adjacent to the pilot seat in the front of the cabin C. Further, the auxiliary rotor 300 is disposed adjacent to the pilot seat such that the balance of the vehicle body can be easily controlled in the longitudinal direction even in the case where the auxiliary rotor 300 is driven. Therefore, the passenger space can be obtained as large as possible.

[0034] When the engine 100 is operated, the battery 500 can be charged using the generator 120, and the main rotor 700 can be driven. The drive shaft 160 can be driven via the clutch 140 connecting the engine 100 and the drive shaft 160. The drive shaft 160 is connected to bevel gears, differential gears, or the like to provide a rotational force to the split shaft 180 extending in the lateral direction. Further, the split shaft 180 rotates the rotor shaft 340 of the auxiliary rotor 300 via bevel gears or the like, thereby mechanically rotating the auxiliary rotor 300 using the engine 100. Therefore, the auxiliary rotor 300 is provided only with a fan and is connected to the engine 100 via a shaft. Since the auxiliary rotor 300 occupies a smaller space than a jet engine or the like, the cabin C can obtain a larger space. Further, the engine 100 can contribute to the charging of the battery 500 or support the power supply to the main rotor 700 in the ordinary time, thereby advantageously increasing the ferry range of the air mobile vehicle.

[0035] That is, the engine 100 is operated as required to provide a mechanical driving force or electric power. The main rotor 700 is driven by the electric power of the battery 500 to perform takeoff, landing, and cruising.

[0036] The auxiliary rotor 300 is disposed adjacent to the center of gravity of the vehicle body such that the balance of the vehicle body is easily controlled during driving of the auxiliary rotor 300. Further, the auxiliary rotor 300 is mechanically connected to the engine 100 via the clutch 140, and receives a mechanical driving force from the engine 100 when the clutch 140 is in the engaged position, thereby performing takeoff, landing, or cruising. The controller monitors the states of the battery 500 and the main rotor 700, and controls the operation of the engine 100 and the clutch 140 only when required, thereby allowing the air mobile vehicle to be driven as environmentally friendly as possible.

[0037] Further, the battery 500 is disposed at a separate location, for example, the rear of the cabin C or collinear with the vehicle body wing, and the main rotor 700 can be disposed in equal numbers on the left and right sides of the battery 500. Such a configuration can effectively maintain the center of gravity of the vehicle body and ensure the maximum space of the cabin C.

[0038] Further, the auxiliary rotors 300 can be respectively provided at right and left sides of the cabin C. According to this configuration, even in the case of failure of at least one of the main rotors 700 at one side, the balance of the vehicle body can be easily controlled in the lateral direction in a sufficiently responsive manner.

[0039] Further, the auxiliary rotors 300 can be provided to coincide with the center of gravity of the vehicle body in the lateral direction, while being located at a distance of 0.002 times the length of the vehicle body or less from the center of gravity of the vehicle body in the longitudinal direction. Thus, even during operation of the auxiliary rotors 300, it is not possible to generate a moment in the longitudinal direction of the vehicle body, so that the balance of the vehicle body can be easily performed without a specific control operation, thereby improving the responsiveness in an emergency.

[0040] Further, the engine 100 is located at a point (or portion) between the auxiliary rotors 300 and the battery 500. The drive shaft 160 is provided at the front of the engine 100, the rightward and leftward extending portions of the split shaft 180 receive driving force via the drive shaft 160, and the auxiliary rotors 300 can be rotated by the split shaft 180. This can facilitate obtaining the center of gravity of the vehicle body, and in particular, can minimize interference with the space of the cabin C, thereby achieving an advantageous effect of the layout.

[0041] Further, as Figure 3 shown, the auxiliary rotors 300 can be oriented in the vertical direction so as to provide downward auxiliary propulsion force when driven, thereby assisting in lifting the vehicle body. In particular, the auxiliary rotors 300 are respectively covered with the covers 320. When the auxiliary rotors 300 are driven, the covers 320 are slid so that the auxiliary rotors 300 are exposed to the outside. In this position, the auxiliary rotors 300 can suck in air from above and discharge the sucked-in air downward.

[0042] The covers 320 are operated using separate motors or the like. When the covers 320 are slid, the covers 320 are accommodated into the vehicle body, and the auxiliary rotors 300 are exposed from above. Thus, when the covers 320 are accommodated, the auxiliary rotors 300 provide downward propulsion for lifting. When the covers 320 cover the auxiliary rotors 300 without being accommodated, air is not introduced from above even when the auxiliary rotors 300 are rotated, thereby significantly limiting the downward propulsion force. Thus, even when the auxiliary rotors 300 at both sides are simultaneously rotated in response to operation of the engine 100, the auxiliary rotors 300 provide propulsion force only when the covers are open. Thus, even in the case of failure of at least one of the main rotors 700 so that the propulsion force is unbalanced in the lateral direction, a responsive operation can be flexibly performed.

[0043] Specifically, when the state of charge of the battery 500 is low, the controller charges the battery 500 or supports power supply to the main rotor 700 by operating the engine 100. When the driving force of the main rotor 700 is insufficient or the main rotor 700 is malfunctioning, the auxiliary rotor 300 can be driven by moving the clutch 140 to the engaged position. Specifically, when the driving force of the main rotor 700 is insufficient, the controller can generate the same auxiliary propulsion force on the right side and the left side by opening both of the covers 320 of the auxiliary rotor 300 on the right side and the auxiliary rotor 300 on the left side. In addition, when one of the main rotor 700 on the right side and the main rotor 700 on the left side is malfunctioning, the controller can open one cover 320 on the same side as the malfunctioning main rotor, thereby generating an auxiliary propulsion force on the side where the malfunction occurs.

[0044] On the other hand, Figure 4 Another embodiment of the present invention is described with reference to FIG. 6. In this case, each of the auxiliary rotors 300 includes an inlet 310 and an outlet 330 that generates an air flow. The auxiliary rotors 300 are rotatably coupled to the vehicle body, and the direction of the outlet 330 can be changed when the auxiliary rotors 300 rotate.

[0045] Specifically, the auxiliary rotor 300 is a centrifugal compressor type rotor that sucks in air in the direction of the rotor shaft thereof and discharges air in the radial direction. The auxiliary rotor 300 is disposed such that the rotor shaft thereof faces the center of gravity of the vehicle body, and the inlet 310 is disposed at a portion where the rotor shaft is disposed, so that the inlet 310 can be oriented in the same direction even when the auxiliary rotor 300 rotates. In addition, the outlet 330 is disposed in the radial direction of the auxiliary rotor 300, so that the auxiliary rotor 300 can assist in lifting propulsion or cruising propulsion in response to the rotation of the auxiliary rotor 300. In addition, an air intake port 301 is provided at the front of the vehicle body. The air intake port 301 can supply air to the inlets 310 of the auxiliary rotors 300 located on both sides through an internal duct 302. In addition, the rotation angle of the auxiliary rotor 300 can be changed using a separate motor 303.

[0046] The present embodiment is advantageous in that the auxiliary rotor 300 not only provides propulsion for lifting, but also selectively provides auxiliary propulsion for cruising. In the same manner, because the passenger cabin C is not provided with a separate component, and the shaft or duct only needs to be designed not to interfere with the passenger cabin, this structure is significantly advantageous for obtaining the space of the passenger cabin C.

[0047] In the air mobile vehicle having a vertical take-off and landing function and a cruising function according to the embodiment of the present application, when the propulsion force of the main rotor is insufficient or at least one of the main rotors malfunctions, an auxiliary propulsion force can be reliably provided to improve the safety of flight. Specifically, even when one of the main rotors malfunctions so that the propulsion forces are unbalanced or the lift function or the cruising function malfunctions, a responsive operation can be flexibly performed to balance the vehicle body.

[0048] While specific embodiments of the application have been described in some detail for the purpose of illustration, it will be appreciated that various modifications, alterations, and substitutions can be made by one skilled in the art without departing from the scope and spirit of the application as disclosed in the appended claims.

Claims

1. An aerial mobile vehicle comprising: a vehicle body including a nacelle; an engine installed in the vehicle body and configured to provide mechanical driving force or electric power; a battery configured to be charged with the electric power from the engine; main rotors configured to operate using electric power of the battery and electric power generated by the engine to perform takeoff, landing, and cruising; auxiliary rotors arranged adjacent to a center of gravity of the vehicle body and mechanically connected to the engine via a clutch, the auxiliary rotors being configured to perform takeoff, landing, or cruising by receiving the mechanical driving force from the engine when the clutch is in an engaged position; and a controller configured to monitor states of the battery and the main rotors and control operations of the engine and the clutch, wherein the auxiliary rotors are disposed to coincide with the center of gravity of the vehicle body in a lateral direction while being positioned within 0.002 times a length of the vehicle body in a longitudinal direction from the center of gravity of the vehicle body. The engine includes an internal combustion engine.

2. The airborne vehicle of claim 1, wherein, The battery is disposed behind the nacelle of the vehicle body or collinearly with a wing of the vehicle body, and the main rotors are disposed in an equal number on left and right sides of the battery.

3. The airborne vehicle of claim 1, wherein, The auxiliary rotors are disposed on left and right sides of the nacelle.

4. The airborne vehicle of claim 1, wherein, The engine is located at a point between the auxiliary rotors and the battery, the engine is provided with a drive shaft at a front portion of the engine, left and right extending portions of a split shaft of the engine are configured to receive the mechanical driving force via the drive shaft, and the auxiliary rotors are configured to be rotated by the split shaft.

5. The airborne vehicle of claim 1, wherein, The auxiliary rotors are oriented in a vertical direction to provide auxiliary propulsion force in a downward direction to assist in lifting the vehicle body.

6. The airborne vehicle of claim 1, wherein, When the auxiliary rotors are driven, the covers are configured to slide to expose the auxiliary rotors to the outside so that the auxiliary rotors suck in air from above and discharge the sucked-in air downward.

7. The aerial mobile vehicle of claim 1, further comprising a cover that covers the auxiliary rotor, wherein, When driving force of the main rotors is insufficient, the controller is configured to generate equal auxiliary propulsion force on left and right sides by opening the covers of the auxiliary rotors on the left and right sides.

8. The airborne vehicle of claim 7, wherein, When one of the main rotors fails, the controller is configured to open the covers of the auxiliary rotors on a same side of the vehicle body as the failed main rotor to generate auxiliary propulsion force on the side where the failure occurs.

9. The airborne vehicle of claim 7, wherein, When a state of charge of the battery is low, the controller is configured to charge the battery by operating the engine or support power supply to the main rotors, and when driving force of the main rotors is insufficient or at least one of the main rotors fails, at least one of the auxiliary rotors is configured to be driven by moving to the engaged position via the clutch.

10. The airborne vehicle of claim 1, wherein, 11. An aerial mobile vehicle comprising: a vehicle body; an engine installed in the vehicle body and configured to provide mechanical driving force or electric power; ​ a battery configured to be charged with the electrical energy from the engine; a main rotor configured to operate using electrical energy of the battery and electrical power generated by the engine to perform take-off, landing, and cruising; auxiliary rotors arranged adjacent to a center of gravity of the vehicle body, each of the auxiliary rotors being rotatably coupled to the vehicle body and mechanically connected to the engine via a clutch, the auxiliary rotors being configured to perform take-off, landing, or cruising by receiving the mechanical driving force from the engine when the clutch is in an engaged position, wherein each of the auxiliary rotors includes an inlet and an outlet configured to generate airflow, and wherein a direction of the outlet is configured to change upon rotation of the auxiliary rotor; and a controller configured to monitor states of the battery and the main rotor, and control operations of the engine and the clutch, wherein the auxiliary rotors are arranged to coincide with the center of gravity of the vehicle body in a lateral direction while being positioned within 0.002 times a length of the vehicle body from the center of gravity of the vehicle body in a longitudinal direction.

12. The airborne vehicle of claim 11, wherein, each of the auxiliary rotors includes a centrifugal compressor type rotor configured to suck in air in a direction of a rotor shaft of the centrifugal compressor type rotor and discharge air in a radial direction, and is arranged such that the rotor shaft is directed toward the center of gravity of the vehicle body, and the inlet is provided at a portion where the rotor shaft is provided such that the inlet is oriented in the same direction even when the auxiliary rotor rotates.

13. The airborne vehicle of claim 12, wherein, the outlet is provided in the radial direction of the auxiliary rotor such that the auxiliary rotor is configured to assist in lift propulsion or cruising propulsion in response to rotation of the auxiliary rotor.

14. The airborne vehicle of claim 12, wherein, the vehicle body includes an air intake at a front portion of the vehicle body, and the air intake is configured to supply air to the inlets of the auxiliary rotors on both sides through an internal duct.

15. A method of operating an airborne vehicle, the airborne vehicle comprising an engine and a battery mounted in a vehicle body, the method comprising: charging the battery with electrical energy from the engine; operating a main rotor using electrical energy of the battery and electrical power generated by the engine to perform take-off, landing, and cruising; operating auxiliary rotors to perform take-off, landing, or cruising by receiving mechanical driving force from the engine when a clutch is in an engaged position, the auxiliary rotors being arranged adjacent to a center of gravity of the vehicle body and being mechanically connected to the engine via the clutch; and monitoring states of the battery and the main rotor, and controlling operations of the engine and the clutch, wherein the auxiliary rotors are arranged to coincide with the center of gravity of the vehicle body in a lateral direction while being positioned within 0.002 times a length of the vehicle body from the center of gravity of the vehicle body in a longitudinal direction.

16. The method of claim 15, wherein, Each of the auxiliary rotors is covered by a cover, the method further comprising: when the auxiliary rotors are driven, moving the cover to expose the auxiliary rotors to the outside, so that the auxiliary rotors suck in air from above and discharge the sucked-in air downward.

17. The method of claim 15, further comprising: when the state of charge of the battery is low, charging the battery or supporting power supply to the main rotors by operating the engine; and when the driving force of the main rotors is insufficient or at least one of the main rotors fails, driving at least one of the auxiliary rotors by moving the clutch to the engaged position.

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