Tilting rotor unmanned aerial vehicle

Abstract

The invention relates to a tilting rotor unmanned aerial vehicle, in particular to an unmanned aerial vehicle combining a flying wing type structure and a multi-shaft tilting rotor. A completely fused flying wing type fuselage is formed by a low-speed wing shape, and no other fuselage characteristics exist except that bilaterally symmetrical wings are directly connected and fused in the middle; a left tilting rotor frame and a right tilting rotor frame are mounted at the left end and the right end of the flying wing type fuselage respectively; at least one to at most six brackets extend from the front part and the rear part respectively, and symmetrical tilting rotor frames are mounted on the brackets; motors and paddles are mounted on all the tilting rotor frames; and an undercarriage is mounted below the flying wing type fuselage. During tilting, a single motor and a single blade are not tilted, but a plurality of power units formed by one or more motors and blades are tilted in groups through a tilting rotor frame. Therefore, the structure is simplified, and the safety and the maneuverability are improved. The landing gear has two types, one type is a foot type landing gear suitable for vertical take-off and landing in a soft site, and the other type is a wheel type landing gear suitable for short-track take-off and landing in a hardened site.

Description

Technical Field

[0001] The present invention relates to a tilt-rotor unmanned aerial vehicle, in particular to an unmanned aerial vehicle combining a flying wing structure with a multi-axis tilt-rotor. Background Art

[0002] At present, fixed-wing aircraft and multi-rotor aircraft have long become the most basic types of unmanned aerial vehicles. The main advantages of fixed-wing aircraft are high flight efficiency, high speed, large payload, and long range; while the main advantages of multi-rotor aircraft are good safety, good maneuverability, and the ability to hover and take off and land vertically. In order to combine the advantages of both and overcome their disadvantages, it is natural to think of combining fixed-wing and multi-rotor.

[0003] However, if a multi-rotor is simply added to a fixed-wing aircraft, the fixed-wing becomes a resistance during takeoff and landing, and the multi-rotor becomes a resistance during level flight, resulting in a reduction in overall efficiency.

[0004] To solve this problem, a tilt-rotor solution has emerged. During takeoff and landing, the axis of the rotor is vertically upward, and the high-speed rotating rotor provides lift to achieve vertical takeoff and landing. During level flight, the axis of the rotor is rotated to the horizontal position, acting like a propeller to provide horizontal thrust.

[0005] Currently, there are mainly two types of tilt-rotor aircraft solutions. One type is mainly based on a fixed-wing, and the rotor is mainly used to achieve vertical takeoff and landing and provide part of the horizontal thrust; the other type is mainly based on a tilt-rotor, and the role of the fixed-wing is relatively minor. The former has poor safety and maneuverability, and the latter has a low payload, a short range, and a slow flight speed.

[0006] The solution proposed by the present invention is a better combination of a fixed-wing and a multi-axis tilt-rotor. Its safety and maneuverability are more like those of a multi-axis rotorcraft, while its payload, range, and flight speed are more like those of a fixed-wing aircraft. Summary of the Invention

[0007] The present invention provides a tilt-rotor unmanned aerial vehicle, which is characterized in that: a fully integrated flying wing fuselage is formed by a low-speed airfoil, and there are no other fuselage features except that the left and right symmetric wings are directly connected and integrated in the middle; a left tilt-rotor frame and a right tilt-rotor frame are respectively installed at the left and right ends of the flying wing fuselage; at least 1 and at most 6 brackets extend forward and backward from the flying wing fuselage, and symmetric tilt-rotor frames are installed on these brackets; motors and blades are installed on all these tilt-rotor frames; a landing gear is installed below the flying wing fuselage.

[0008] Why adopt a fully integrated flying wing fuselage? Because we want to make full use of the advantages of good safety and maneuverability of multi-rotors. Naturally, we need to simplify all the characteristics related to maneuverability on traditional fixed wings. And a fixed wing doesn't need to provide any other functions except lift. So we directly cancel the traditional fuselage and directly construct an integrated flying wing fuselage by completely integrating the left and right symmetric wings in the middle. Such a fixed wing aircraft that doesn't distinguish between the fuselage and the wings at all and has no structures such as tail wings, side wings, and flaps has very poor safety and maneuverability itself, and generally such a design won't be made. However, after completely handing over the safety and maneuverability to the multi-axis tilt-rotor, the problem is solved. So the key to this design lies in fully trusting and giving play to the advantages of safety and maneuverability of multi-rotors.

[0009] Since it is clear that the main function of the flying wing fuselage is to provide lift, naturally we need to adopt a suitable airfoil and an angle of attack with a suitable lift-to-drag ratio. For low-speed UAVs, the first choice is of course a low-speed airfoil. To ensure reasonable structural strength, the thickness of the airfoil cannot be too thin, otherwise the cost will instead increase. Adopt a low-speed airfoil with a reasonable thickness, and then determine the angle of attack corresponding to the maximum lift-to-drag ratio according to the requirements of the cruise speed. To avoid stalling and improve stability and reliability, the actual angle of attack should be slightly smaller than this optimal angle of attack and significantly smaller than the critical angle of attack.

[0010] Therefore, generally speaking, the angle between the chord line of the airfoil and the horizontal plane on all longitudinal sections (sections parallel to the aircraft's forward direction and perpendicular to the ground) of this flying wing fuselage is 0 - 30 degrees, and the specific value is determined according to the angle of attack when the lift-to-drag ratio of the selected low-speed airfoil approaches the maximum value at the designed cruise speed.

[0011] In addition to the fully integrated flying wing fuselage, another obvious difference between the present invention and existing tilt-rotor aircraft is that instead of tilting a single motor and blade, several power units composed of one or more motors and blades are tilted in groups through a tilt-rotor frame. This simplifies the structure and improves safety and maneuverability.

[0012] Due to the limitations of current battery and motor technologies, many multi-rotor UAVs with large payloads are hybrid electric and gasoline-powered. They often have a main rotor directly driven by an engine to provide lift during vertical takeoff and landing. It will naturally become very complicated to tilt this main rotor.

[0013] The tilt-rotor UAV proposed by the present invention, however, adopts another scheme, that is, it consists of many smaller motors and rotors to form power units, and many such small power units are used to achieve a relatively large vertical takeoff and landing lift and horizontal flight thrust. Therefore, it is necessary to tilt these small power units in groups through a tilt-rotor frame.

[0014] These tilt-rotor mounts need to be installed on the flying-wing fuselage. According to different installation positions and methods, they can be divided into three categories, namely the left tilt-rotor mount, the right tilt-rotor mount, and the symmetric tilt-rotor mount.

[0015] The main body of the left tilt-rotor mount is tubular; the right end directly extends into the horizontal hole at the left end of the flying-wing fuselage and can rotate around its own axis, or is connected to the rotating shaft in the horizontal hole at the left end of the flying-wing fuselage through a flange or sleeve; there are several vertically upward hole positions on the left side for installing motors, and then blades can be installed on the motors.

[0016] The main body of the right tilt-rotor mount is tubular; the left end directly extends into the horizontal hole at the right end of the flying-wing fuselage and can rotate around its own axis, or is connected to the rotating shaft in the horizontal hole at the right end of the flying-wing fuselage through a flange or sleeve; there are several vertically upward hole positions on the right side for installing motors, and then blades can be installed on the motors.

[0017] The main body of the symmetric tilt-rotor mount is tubular; the middle part is sleeved into the horizontal hole on the bracket protruding from the front and back of the flying-wing fuselage and can rotate around its own axis, or is connected to the rotating shaft in the horizontal hole on the bracket protruding from the front and back of the flying-wing fuselage through a flange or sleeve; several vertically upward hole positions are symmetrically distributed at both the left and right ends for installing motors, and then blades can be installed on the motors.

[0018] In order to adapt to different takeoff and landing sites, the present invention proposes two types of landing gears.

[0019] One type is the foot type, with 4 feet installed at the bottom. The cross-sectional shape of each foot is a low-speed airfoil shape, hollow inside, and made of medium-hard rubber. During level flight, the 4 feet can provide a certain amount of lift to offset part of the weight of the landing gear. During landing, the bottom area of the 4 feet is relatively large, which can adapt to relatively soft sites and achieve vertical takeoff and landing. Elastic blocks are installed between the 4 feet and the trapezoidal frame to ensure that the bottom surface of the feet has a certain angle of attack during flight to increase lift, and can play a role in buffering and vibration absorption during landing.

[0020] The other type is the wheel type, with 4 to 8 vacuum tire casters installed at the bottom, suitable for takeoff and landing on hardened sites and short-distance maneuvering. As long as there is a small piece of site for short-distance takeoff by sliding, the advantages of the fixed wing can be utilized more fully, and the power requirement during takeoff and landing can be significantly reduced. After the requirements for the motors and batteries are reduced, the cost of the entire aircraft can be significantly reduced.

[0021] Whether it is the foot type or the wheel type landing gear, the middle part is a trapezoidal frame formed by connecting carbon fiber tubes through tube-end hinges, and the tube-end hinges are fixedly connected to both ends of the carbon fiber tubes.

[0022] For better buffering and vibration absorption during landing, the lower part of the landing gear trapezoidal frame is designed as a combined telescopic sleeve, which consists of a hinge, an inner tube, an outer tube, a rubber piston head, a piston head fixing plate, and bolts. The rubber piston head is fixed to the piston head fixing plate with bolts, and the piston head fixing plate is fixed to the end of the inner tube, so that the inner tube, the piston head fixing plate, and the rubber piston head are connected as a whole and can slide inside the outer tube with relatively large resistance. By using the friction between the piston head and the outer tube wall, as well as the compression and vacuum effects of the air inside the tube, most of the impact energy during landing can be absorbed. Description of the Drawings

[0023] Figure 1 Schematic structural diagram of the footed landing gear during vertical takeoff Figure 2 is Figure 1 top view of Figure 3 is Figure 1 side view of Figure 4 is Figure 1 front view of Figure 5 Schematic structural diagram of the footed landing gear during horizontal flight Figure 6 is Figure 5 top view of Figure 7 is Figure 5 side view of Figure 8 is Figure 5 front view of Figure 9 Schematic structural diagram of the wheeled landing gear during vertical takeoff Figure 10 is Figure 9 top view of Figure 11 is Figure 9 side view of Figure 12 is Figure 9 front view of Figure 13 Schematic structural diagram of the wheeled landing gear during horizontal flight Figure 14 is Figure 13 top view of Figure 15 is Figure 13 side view of Figure 16 is Figure 13 front view of Figure 17 Schematic structural diagram of the footed landing gear Figure 18 Schematic structural diagram of the telescopic sleeve at the lower part of the trapezoidal frame 1 Flying wing fuselage, 2 Front support, 3 Symmetrical tilting rotor frame, 4 Power unit (motor and propeller), 5 Right tilting rotor frame, 6 Rear support, 7 Landing gear, 8 Pneumatic tire caster, 9 Combined telescopic sleeve, 10 Left tilting rotor frame, 11 Foot, 12 Hinge, 13 Inner tube, 14 Outer tube, 15 Piston head fixing plate, 16 Rubber piston head, 17 Bolt, 18 Trapezoidal frame, 19 Elastic block Specific implementation mode

[0024] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited by this embodiment.

[0025] Embodiment 1: As Figure 1 shown, the fuselage adopts a large-thickness GOE 561 low-speed airfoil, the planar shape is an ellipse, the left and right wings are symmetrical and completely integrated into a flying wing fuselage in the middle, the angle of attack is 5 degrees, and it is suitable for flying at a speed of 150 km / h. Two supports are extended forward and backward respectively, and symmetrical tilting rotor frames are installed in the horizontal holes on the supports, and 4 sets of motors and propellers are installed on each symmetrical tilting rotor frame. A left tilting rotor frame is installed on the left side of the fuselage, and a right tilting rotor frame is installed on the right side, and 4 sets of motors and propellers are installed on each of them. The whole aircraft has a total of 6 tilting rotor frames and installs 24 sets of motors and propellers.

[0026] The landing gear is of the foot type and can take off and land vertically on soft ground.

[0027] Embodiment 2: As Figure 9 shown, the fuselage adopts a large-thickness GOE 561 low-speed airfoil, the planar shape is an ellipse, the left and right wings are symmetrical and completely integrated into a flying wing fuselage in the middle, the angle of attack is 5 degrees, and it is suitable for flying at a speed of 150 km / h. Two supports are extended forward and backward respectively, and symmetrical tilting rotor frames are installed in the horizontal holes on the supports, and 4 sets of motors and propellers are installed on each symmetrical tilting rotor frame. A left tilting rotor frame is installed on the left side of the fuselage, and a right tilting rotor frame is installed on the right side, and 4 sets of motors and propellers are installed on each of them. The whole aircraft has a total of 6 tilting rotor frames and installs 24 sets of motors and propellers.

[0028] The landing gear is of the wheel type and can take off and land by short-distance taxiing on a hardened ground. The takeoff and landing power can be significantly reduced compared with Embodiment 1, so the requirements for batteries and motors can be significantly reduced, thus significantly reducing the cost.

Claims

1. A tilt-rotor unmanned aerial vehicle, characterized in that: A fully integrated flying wing fuselage is formed by a low-speed airfoil. There are no other fuselage features except that the left and right symmetric wings are directly connected and integrated in the middle. A left tilt-rotor frame and a right tilt-rotor frame are respectively installed at the left and right ends of the flying wing fuselage. At least 1 and at most 6 brackets extend forward and backward from the flying wing fuselage, and symmetric tilt-rotor frames are installed on these brackets. Motors and blades are installed on all these tilt-rotor frames. Landing gears are installed under the flying wing fuselage.

2. The fully integrated flying wing fuselage according to claim 1, characterized in that, The angle between the chord line of the airfoil and the horizontal plane in all longitudinal sections (sections parallel to the aircraft's forward direction and perpendicular to the ground) is 0 - 30 degrees, and the specific value is determined according to the angle of attack when the lift-to-drag ratio of the selected low-speed airfoil approaches the maximum value at the design cruise speed.

3. The left tilting rotor frame according to claim 1, characterized in that: The main body is tubular; the right end directly extends into the left horizontal hole of the flying wing fuselage and can rotate around its own axis, or is connected to the rotating shaft in the left horizontal hole of the flying wing fuselage by means of a flange or a sleeve; there are several vertically upward hole positions on the left side where motors can be installed, and then blades can be installed on the motors.

4. The right-tilting tilt-rotor frame according to claim 1, characterized in that: The main body is tubular; the left end directly extends into the right horizontal hole of the flying wing fuselage and can rotate around its own axis, or is connected to the rotating shaft in the right horizontal hole of the flying wing fuselage by means of a flange or a sleeve; there are several vertically upward hole positions on the right side where motors can be installed, and then blades can be installed on the motors.

5. The symmetric tilt-rotor frame according to claim 1, wherein: The main body is tubular; the middle part is sleeved into the horizontal holes on the brackets extending forward and backward from the flying wing fuselage and can rotate around its own axis, or is connected to the rotating shaft in the horizontal holes on the brackets extending forward and backward from the flying wing fuselage by means of a flange or a sleeve; several vertically upward hole positions are symmetrically distributed at both the left and right ends where motors can be installed, and then blades can be installed on the motors.

6. The landing gear according to claim 1, wherein, 4 feet are installed at the bottom, and the cross-sectional shape of each foot is in the shape of a low-speed airfoil.

7. The landing gear according to claim 1, characterized in that, 4 to 8 vacuum tire casters are installed at the bottom.

8. The landing gear according to claim 1, characterized in that The middle part is a trapezoidal frame formed by connecting carbon fiber tubes through tube-end hinges, and the tube-end hinges are fixedly connected to both ends of the carbon fiber tubes.

9. The landing gear trapezoidal frame according to claim 8, characterized in that, The lower part of the trapezoidal frame is a combined telescopic sleeve, which consists of a hinge, an inner tube, an outer tube, a rubber piston head, a piston head fixing plate, and bolts. The rubber piston head is fixed to the piston head fixing plate with bolts, and the piston head fixing plate is fixed to the end of the inner tube, so that the inner tube, the piston head fixing plate, and the rubber piston head are connected into a whole and can slide inside the outer tube with relatively large resistance.

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