flying object

Abstract

To provide an aircraft (especially a multirotor) whose body shape reduces unwanted positive lift and drag in the aircraft's cruising attitude, thereby improving its cruising speed. [Solution] An aircraft comprising a plurality of rotor blades including propellers and motors, characterized in that it comprises a main body with an inverted wing shape. The main body has an angle of attack that does not generate lift or generates negative lift during cruising. The main body has a positive angle of attack of 12 degrees or less. Furthermore, it comprises a payload section capable of carrying payloads. The payload section is connected to the main body via a connecting section.

Description

Technical Field

[0001] The present invention relates to a flying object.

Background Art

[0002] In recent years, research and demonstration experiments have been underway towards the practical application of services using flying objects such as drones and unmanned aerial vehicles (UAVs) (hereinafter collectively referred to as "flying objects"). In general, a flying object (hereinafter collectively referred to as a multicopter) that has a plurality of fixed-pitch propellers and moves by tilting the body has a simpler structure compared to a VTOL aircraft equipped with a tilt rotor and a tilt wing mechanism on the main wing. Therefore, it has the advantages of being easy to manufacture and maintain, and having few failure points.

[0003] However, a multicopter-shaped body has inferior fuel efficiency compared to a VTOL aircraft that flies using the lift generated by the main wing, and the drag generated by the main body is not taken into account. In view of such a situation, Patent Document 1 discloses a flying object that reduces the load on the rotary wing. (For example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, by setting the angle between the rotation axis of the rotary wing and the normal line of the reference plane of the main body to be between 5 and 30 degrees, a positive angle of attack is formed when the rotary wing aircraft moves forward, and the load on the rotary wing is reduced by the lift generated by the main body. An aircraft (hereinafter collectively referred to as a conventional aircraft) aimed at improving the flight time has been developed. <C

[0006] A multirotor constantly consumes energy while it remains airborne. Conventional designs reduce energy consumption and improve flight time. However, as shown in Figures 16-17, in conventional designs where the main body 10 generates positive lift during cruising, reducing the load on the rotor blades, increasing the rotor speed to increase cruising speed results in increased upward lift from both the rotor blades and the lift generated by the main body 10. This causes the aircraft to be unable to move forward horizontally and instead move diagonally upward, leading to a decrease in forward speed.

[0007] Furthermore, if the rotation speed of the rotor blades is reduced to prevent the aircraft from moving upwards, the thrust will decrease in proportion to the reduction in rotation speed, thus lowering the aircraft's cruising speed.

[0008] In practical services such as transportation, inspection, and photography, speed is required, and this is especially true in the transportation sector. Furthermore, improving speed leads to improved energy consumption and overall fuel efficiency of the flight system. For example, in a flight from point A to point B, the less time the aircraft spends in the air, the less energy is consumed. Reducing the load on the rotor blades, as in conventional aircraft, also reduces energy consumption, but as mentioned above, this comes at the cost of increasing the angle of attack of the main body 10, which prevents the aircraft from reaching point B via the shortest route, or it reduces the rotation speed of the rotor blades to prevent this, resulting in a delay in reaching point B, and the increased flight time leads to increased energy consumption.

[0009] To move a multirotor at higher speeds, the rotor blades that generate thrust need to rotate faster, and increasing the rotation speed of the rotor blades is possible by increasing the load on the rotor blades.

[0010] One way to prevent a decrease in rotor speed is to increase the load each rotor can handle by making the aircraft heavier. However, it is clear that adding unnecessary weight to the aircraft negatively impacts fuel efficiency.

[0011] Therefore, one objective of the present invention is to provide an aircraft (especially a multicopter) whose body shape is such that, in the aircraft's cruising attitude, the main body suppresses drag while minimizing unnecessary positive lift, thereby improving cruising speed. [Means for solving the problem]

[0012] According to the present invention, it is possible to provide an aircraft having a plurality of rotor blades including propellers and motors, and characterized in that it has a main body with an inverted wing shape. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a body shape that improves the cruising speed of an aircraft. [Brief explanation of the drawing]

[0014] [Figure 1] This is a conceptual diagram of the aircraft according to the present invention, viewed from the side during cruising. [Figure 2] Figure 1 is a functional block diagram of the aircraft. [Figure 3] Figure 1 is a side view of the aircraft while it is hovering. [Figure 4] Figure 1 is a top view of the aircraft while it is hovering. [Figure 5] This is a diagram showing a typical airfoil shape. [Figure 6] Figure 5 is a graph showing the lift characteristics of the airfoil shape. [Figure 7] Figure 5 is a graph showing the drag characteristics of the airfoil shape. [Figure 8] This is a side view of an example of the configuration of an aircraft according to the present invention during cruising. [Figure 9] Figure 8 is a side view of the aircraft while it is hovering. [Figure 10] Top view of the flying object during hovering in FIG. 8. [Figure 11] Schematic diagram showing the main body shape of the flying object in FIG. 8. [Figure 12] Graph showing the lift characteristics of the shape in FIG. 11. [Figure 13] Graph showing the drag characteristics of the shape in FIG. 11. [Figure 14] Side view of the configuration example of the flying object according to the present invention during cruising. [Figure 15] Side view of the flying object in FIG. 14 during hovering. [Figure 16] Side view of a conventional aircraft during cruising. [Figure 17] Side view of the aircraft in FIG. 16 during hovering. [Figure 18] Top view of the aircraft in FIG. 16 during hovering.

Mode for Carrying Out the Invention

[0015] The content of the embodiment of the present invention will be listed and described. The flying object according to the embodiment of the present invention has the following configuration. [Item 1] A flying object including a plurality of rotary wings including propellers and motors, Comprising a main body portion having an inverse airfoil shape, A flying object characterized by the above. [Item 2] The main body portion has an angle of attack that does not generate lift or generates negative lift during cruising, The flying object according to Item 1, characterized by the above. [Item 3] The main body portion has a positive angle of attack of 12 degrees or less, The flying object according to Item 1, characterized by the above. [Item 4] Furthermore, it includes a mounting portion capable of mounting a load, The flying object according to any one of Items 1 to 3, characterized by the above. [Item 5] The mounting portion is connected to the main body portion via a connecting portion. The flying object described in item 4, characterized by the features described herein. [Item 6] The connecting portion maintains the mounting portion in a predetermined position. The flying object described in item 5, characterized by the features described herein. [Item 7] The aforementioned predetermined posture is horizontal. The flying object described in item 6, characterized by the features described therein. [Item 8] Furthermore, the rotor blades are provided on the main body. An aircraft characterized by any one of items 1 to 7.

[0016] <Details of embodiments according to the present invention> The following describes an aircraft according to an embodiment of the present invention with reference to the drawings.

[0017] <Details of the first embodiment>

[0018] As shown in Figure 1, the aircraft 100 according to an embodiment of the present invention is equipped with a flight section 20 that includes at least a main body 10, a plurality of rotors consisting of propellers 110 and motors 111, a motor mount supporting the motors, a frame 21, and other elements for flight, and it is desirable that it is equipped with energy (for example, a secondary battery, fuel cell, fossil fuel, etc.) to operate them.

[0019] Note that the aircraft 100 shown in the illustration is simplified for the purpose of facilitating the explanation of the structure of the present invention, and detailed components such as the control unit are not shown.

[0020] The aircraft 100 has the direction of arrow D (-Y direction) in the diagram as its forward direction (more details will be provided later).

[0021] In the following explanation, terms may be used according to the following definitions: Forward / backward direction: +Y and -Y directions, Up / down direction (or vertical direction): +Z and -Z directions, Left / right direction (or horizontal direction): +X and -X directions, Forward direction (forward): -Y direction, Backward direction (backward): +Y direction, Upward direction (up): +Z direction, Downward direction (down): -Z direction

[0022] The propeller 110 rotates in response to the output from the motor 111. The rotation of the propeller 110 generates thrust to allow the aircraft 100 to take off from its starting point, move, and land at its destination. The propeller 110 can rotate to the right, stop, and rotate to the left.

[0023] The propeller 110 of the aircraft of the present invention has one or more blades. The number of blades (rotor) can be any number (e.g., 1, 2, 3, 4, or more). The shape of the blade can be any shape, such as flat, curved, twisted, tapered, or a combination thereof. The shape of the blade can be changed (e.g., extension, folding, bending, etc.). The blade may be symmetrical (having the same upper and lower surfaces) or asymmetrical (having upper and lower surfaces of different shapes). The blade can be formed into an airfoil, wing, or a geometric shape suitable for generating dynamic aerodynamic forces (e.g., lift, thrust) when the blade is moved through the air. The geometric shape of the blade can be appropriately selected to optimize the dynamic aerodynamic characteristics of the blade, such as increasing lift and thrust and reducing drag.

[0024] Furthermore, the propellers of the aircraft of the present invention may be fixed-pitch, variable-pitch, or a combination of fixed-pitch and variable-pitch, but are not limited to these.

[0025] The motor 111 generates the rotation of the propeller 110, and the drive unit may include, for example, an electric motor or an engine. The blades are driveable by the motor and rotate around the motor's axis of rotation (for example, the motor's long axis).

[0026] The blades can all rotate in the same direction, or they can rotate independently. Some blades can rotate in one direction, while others rotate in other directions. The blades can all rotate at the same speed, or they can rotate at different speeds. The speed can be determined automatically or manually based on the dimensions of the moving object (e.g., size, weight) and the control state (speed, direction of movement, etc.).

[0027] The aircraft 100 uses a flight controller or radio control system to determine the rotation speed of each motor and the flight angle according to the wind speed and direction. This allows the aircraft to move, such as ascending and descending, accelerating and decelerating, and changing direction.

[0028] The aircraft 100 can perform autonomous flight in accordance with routes and rules set in advance or during flight, or it can be controlled using a remote control.

[0029] The aforementioned aircraft 100 has the functional blocks shown in Figure 2. Note that the functional blocks in Figure 2 represent a minimum reference configuration. The flight controller is a so-called processing unit. The processing unit may have one or more processors, such as a programmable processor (e.g., a central processing unit (CPU)). The processing unit has memory (not shown) that is accessible. The memory stores logic, code, and / or program instructions that the processing unit can execute to perform one or more steps. The memory may include a separable medium such as an SD card or random access memory (RAM), or an external storage device. Data acquired from cameras and sensors may be directly transmitted to and stored in memory. For example, still images and video data captured by a camera may be recorded in internal or external memory.

[0030] The processing unit includes a control module configured to control the state of the rotorcraft. For example, the control module has six degrees of freedom (translational motion x, y, and z, and rotational motion θ). x θ y and θ z The control module controls the propulsion mechanism (motors, etc.) of a rotary-wing aircraft to adjust its spatial arrangement, speed, and / or acceleration. The control module can control one or more of the onboard components and the state of the sensors.

[0031] The processing unit can communicate with a transceiver configured to transmit and / or receive data from one or more external devices (e.g., terminals, display devices, or other remote controllers). The transceiver can use any suitable means of communication, such as wired or wireless communication. For example, the transceiver can utilize one or more of the following: local area networks (LANs), wide area networks (WANs), infrared, wireless, Wi-Fi, point-to-point (P2P) networks, telecommunications networks, cloud communication, etc. The transceiver can transmit and / or receive one or more of the following: data acquired by sensors, processing results generated by the processing unit, predetermined control data, user commands from terminals or remote controllers, etc.

[0032] The sensors according to this embodiment may include inertial sensors (accelerometers, gyroscopes), GPS sensors, proximity sensors (e.g., LiDAR), or vision / image sensors (e.g., cameras).

[0033] As shown in Figures 1 and 3, the flight section 20 of the aircraft 100 in the embodiment of the present invention tilts forward in the direction of travel during flight. The tilted rotor generates upward lift and thrust in the direction of travel, thereby causing the aircraft 100 to move forward.

[0034] The aircraft 100 is equipped with a main body 10 capable of housing the onboard processing unit, battery, and other payloads. The main body 10 is fixedly connected to the flight unit 20, and its attitude changes in accordance with the attitude changes of the flight unit 20. By optimizing the shape of the main body 10 in the cruising attitude of the aircraft 100, which is expected to be maintained for a long period of time while the aircraft 100 is moving, and by improving its speed, the flight time is efficiently shortened.

[0035] The main body 10 should preferably have an outer shell with sufficient strength to withstand flight and takeoff / landing. For example, plastic, FRP, etc., are suitable materials for the outer shell because they have rigidity and waterproofing properties. These materials may be the same as the frame 21 (including the arms) included in the flight section 20, or they may be different materials.

[0036] Furthermore, the motor mount, frame 21, and main body 10 of the flight unit 20 may be constructed by connecting each component, or they may be molded together as a single unit using a monocoque structure or integral molding (for example, the motor mount and frame 21 may be molded together as a single unit, or the motor mount, frame 21, and main body 10 may all be molded together as a single unit, etc.). By integrating the components, it becomes possible to smooth the joints between each component, which can lead to reduced drag and improved fuel efficiency, as is the case with aircraft such as blended wing bodies and lifting bodies.

[0037] The shape of the main body 10 of the aircraft 100 is such that the aircraft 100 has low drag and low unwanted lift in its cruising attitude (the "inverted wing" shape described below). More preferably, it is a shape with even less drag (for example, streamlined), and the lift generated may be in the negative direction. Figure 1 illustrates the negative lift generated by the main body 10.

[0038] Figure 5 shows an example of an airfoil (Gottingen 508). For example, in a typical airfoil A used to generate lift, such as the main body 10 of a conventional aircraft shown in Figure 16, the camber line 13 has a curved shape that is convex upward in the center (hereinafter collectively referred to as arched), and a large portion of the camber line 13 is above the chord 12, or the entire camber line 13 is above the chord 12. On the other hand, in an airfoil B obtained by inverting a typical airfoil A, such as the main body 10 of the present invention shown in Figure 1, the camber line 13 has an inverted arch shape, and a large portion of the camber line 13 is below the chord 12, or the entire camber line 13 is below the chord 12. This shape, in which the camber line 13 has an inverted arch shape and a large portion of the camber line 13 is below the chord 12, or the entire camber line 13 is below the chord 12, will be collectively referred to as an inverted airfoil shape.

[0039] Figure 6 shows the lift characteristics and Figure 7 shows the drag characteristics of airfoils A and B in Figure 5 when compared to an atmosphere of approximately 10 m / s in a standard atmosphere. Ideally, it is better to have less drag from the main body 10, so when we look at the lift for airfoils A and B at angles of attack where the maximum drag is 0.04 or less and 0.03 or less (the allowable maximum drag can be set as appropriate), as shown in Figure 6, the inverted airfoil B has less lift than airfoil A. In other words, the inverted airfoil shape has less drag and less unwanted lift compared to other shapes (especially airfoil shapes). In particular, it is shown that the inverted airfoil shape does not produce positive lift, or even negative lift, even at positive angles of attack (in Figure 6, it can be seen that no positive lift is produced at positive angles of attack of approximately 12 degrees or less). As shown in Figure 6, even with airfoil A, there are angles of attack ranges where positive lift is not generated, or even negative lift is generated. However, as shown in Figure 7, drag increases significantly, reducing forward propulsion efficiency.

[0040] Therefore, if the shape of the main body 10 of the forward-moving aircraft 100 is an inverted wing shape, the drag generated by the main body 10 is reduced, and unnecessary lift is also reduced, thus improving efficiency during forward movement.

[0041] More preferably, the shape of the main body 10 is inverted wing type, and the angle of attack of the aircraft 100 in its cruising attitude does not generate lift. In this case, since no lift is generated by the main body of a conventional aircraft, it is not necessary to reduce the rotation speed of the rotor blades during cruising, and the cruising speed of the aircraft is not reduced. Even more preferably, if the shape of the main body 10 is inverted wing type, and the angle of attack of the aircraft 100 in its cruising attitude generates negative lift, the lift from the rotor blades is suppressed compared to the case where no lift is generated. Therefore, an increase in lift with increasing rotation speed is permitted, and the increased thrust makes it possible to improve the cruising speed of the aircraft.

[0042] As shown in Figures 8-10, the aircraft 100 may be equipped with a loading section 30 that can accommodate cargo (objects to be transported) by storing them inside, for example, for use in transporting packages such as delivery services. Furthermore, by connecting the loading section 30 via a connecting section 31 such as a pivot axis or a gimbal with one or more degrees of freedom, the loading section 30 and the cargo it contains can be maintained in a predetermined position (e.g., horizontal) regardless of the attitude of the aircraft 100, so that they can be displaced independently of the main body 10 and the flight section 20.

[0043] To more actively maintain the attitude of the mounting section 30, a sensor that detects the angle, or a mechanism that can maintain the attitude of the mounting section, such as a motor or servo, may be used. Alternatively, the position of the gimbal connection section 31 may be set above the center of gravity of the mounting section 30, and the attitude of the mounting section 30 may be maintained using its own weight.

[0044] As shown in the schematic diagram in Figure 11, the airfoil D of the main body 10 of the aircraft 100 in Figure 8 has an inverted arch shape with a camber line 13 that is below the chord 12, and thus has an inverted airfoil shape, achieving the same effect as airfoil B described above. For comparison, airfoil C, which is airfoil D inverted vertically, is used as another example of airfoil A.

[0045] Figure 12 shows the lift characteristics and Figure 13 shows the drag characteristics of airfoils C and D in Figure 11 when subjected to a standard atmosphere with a drag of approximately 10 m / s. These graphs also show that, within the same drag range (for example, with maximum drag of 0.04 or less and 0.03 or less), the inverted airfoil D generates less lift than airfoil C. Therefore, even an aircraft equipped with the inverted airfoil shape of Figure 11 can suppress unnecessary lift and reduce the increase in drag.

[0046] The lift and drag characteristics exhibited by the main body 10 during cruising vary depending on various factors such as cruising speed, shape, and dimensions of the main body. Therefore, it is desirable that the shape of the main body be determined considering the aircraft's intended use and operating environment. In this case, by selecting a shape that minimizes unnecessary lift (and even generates negative lift) with a smaller increase in drag, the forward speed of the aircraft can be efficiently improved.

[0047] <Details of the second embodiment> In detail of the second embodiment according to the present invention, components that overlap with those in the first embodiment perform similar operations, so a further explanation will be omitted.

[0048] As shown in Figures 14 and 15, the main body 10 may be equipped with control surfaces 11. By deploying the control surfaces 11 and giving them the function of spoilers, it is possible to reduce the lift generated by the main body 10. For example, as shown in Figures 5 and 11, even if the shape generates a large positive lift when the control surfaces 11 are not deployed, deploying the control surfaces 11 allows the main body 10 to reduce unnecessary lift, more preferably generate no lift, and even more preferably generate negative lift. In particular, for aircraft used at low cruising speeds (for example, an airspeed of about 10 km / h), it is preferable to use a main body 10 equipped with control surfaces 11 in a shape that prioritizes the reduction in drag over the reduction in the amount of positive lift generated.

[0049] Furthermore, it is possible to increase negative lift by adding a rotor blade 11 to the main body 10, which does not generate positive lift even when the rotor blades are not deployed.

[0050] The configuration of the aircraft in each embodiment can be implemented by combining multiple components. It is desirable to consider the most suitable configuration as appropriate, taking into account the cost of manufacturing the aircraft and the environment and characteristics of the place where the aircraft will be operated.

[0051] The embodiments described above are merely illustrative to facilitate understanding of the present invention and are not intended to limit its interpretation. The present invention can be modified and improved without departing from its spirit, and it goes without saying that the present invention includes equivalents thereof. [Explanation of Symbols]

[0052] 10 Main body 11 Moving blade 12 Wing chord lines 13 Camber Line 20 Flight Division 21 frames 30 Mounting section 31 Connection part 100 flying objects 110a~110h Propeller 111a~111h Motor

Claims

1. An aircraft having multiple rotor blades including propellers and motors, It has a body with an inverted wing shape, An aircraft characterized by the following features.

2. The main body, when cruising, has an angle of attack that does not generate lift, or generates negative lift. The flying object according to feature 1.

3. During cruising, the main body has a positive angle of attack of 12 degrees or less. The flying object according to feature 2.

4. Furthermore, it is equipped with a mounting section capable of mounting loads, The aircraft according to any one of claims 1 to 3.

5. The mounting portion is connected to the main body portion via a connecting portion. The flying vehicle according to feature 4.

6. The connecting portion maintains the mounting portion in a predetermined position. The flying object according to feature 5.

7. The aforementioned predetermined posture is horizontal. The flying vehicle according to feature 6.

8. Furthermore, the rotor blades are provided on the main body. The aircraft according to any one of claims 1 to 7.

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