Rotorcraft

Abstract

A rotorcraft includes a fuselage and a plurality of rotor portions. The fuselage has a front end portion, a rear end portion, and two side end portions, and a reference plane passing through the front end portion, the rear end portion, and the two side end portions. The rotor portions are disposed on the fuselage, wherein each rotor portion includes at least one rotor blade and a rotating shaft connected to the at least one rotor blade, and the rotor blade rotates along an axial direction of the rotating shaft connected thereto. An angle between the axial direction of each rotating shaft and a normal direction of the reference plane is between 5 degrees and 30 degrees. The rotorcraft can increase additional lift to help reduce the weight of the rotorcraft.

Description

Technical Field

[0001] This invention relates to an aircraft, and more particularly to a rotorcraft. Background Technology

[0002] Drones are a new type of aircraft, and most current drones have a light weight to maintain a certain hovering time. For example, how to further improve the hovering time of common drones such as quadcopters is a topic of interest to many.

[0003] This "Background Art" section is only for the purpose of helping to understand the content of this invention. Therefore, the content disclosed in the "Background Art" may include some known technologies that are not known to those skilled in the art. In addition, the content disclosed in the "Background Art" does not represent the problems to be solved by such content or one or more embodiments of this invention, nor does it represent that it was known or recognized by those skilled in the art before this application was filed. Summary of the Invention

[0004] This invention provides a rotorcraft that can increase additional lift force to help reduce the rotorcraft's weight.

[0005] The advantages of this invention can be further understood from the technical features disclosed herein.

[0006] The gyroplane provided by this invention includes a fuselage and a plurality of rotor-wing parts. The fuselage has a front end, a rear end, and two sides, as well as a reference plane passing through the front end, rear end, and two sides. These rotor-wing parts are disposed on the fuselage, each rotor-wing part including at least one blade and a shaft, the shaft connecting the blade. The blade rotates along the axial direction of the shaft to which it is connected. The angle between the axial direction of each shaft and the normal direction of the reference plane is between 5 degrees and 30 degrees.

[0007] Based on the above, since the angle between the axial direction of each rotating shaft and the normal direction of the reference plane is between 5 degrees and 30 degrees, when the rotorcraft of the present invention flies forward, it can form a positive angle of attack (Positive AOA), so that the bottom surface of the fuselage can become the windward surface of the air stream, thereby generating additional lift to reduce the load of the rotorcraft.

[0008] To make the above-mentioned features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings for detailed explanation. Attached Figure Description

[0009] Figure 1A This is a side view schematic diagram of a rotorcraft according to an embodiment of the present invention.

[0010] Figure 1B It is the airflow that exerts force on Figure 1A A force diagram drawn for a rotorcraft.

[0011] Figure 1C yes Figure 1A A force diagram illustrating the lift and drag of a rotorcraft.

[0012] Figure 2A This is a schematic diagram of the airfoil, designated NACA66-018 by the National Advisory Committee for Aeronautics (NACA).

[0013] Figure 2B yes Figure 2A A schematic diagram showing how the lift coefficient of an airfoil varies with the angle of attack (AOA).

[0014] Figure 3 This is a schematic diagram illustrating how the flight time of a rotorcraft varies with its weight according to an embodiment of the present invention. Detailed Implementation

[0015] The foregoing and other technical contents, features, and effects of this invention will be clearly presented in the following detailed description of one embodiment with reference to the accompanying drawings. The directional terms used in the following embodiments, such as up, down, left, right, front, or back, are merely for reference to the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0016] Figure 1A This is a side view schematic diagram of a rotorcraft according to an embodiment of the present invention. Please refer to... Figure 1AThe gyroplane 100 includes a fuselage 110 and a plurality of rotor sections 120, wherein the rotor sections 120 are disposed on the fuselage 110 and can surround the fuselage 110. Each rotor section 120 includes at least one blade 121 and a shaft 122, and the shaft 122 of the same rotor section 120 is connected (shaft-connected) to the blade 121, wherein the blade 121 rotates along the axial direction 122a of the shaft 122 to which it is connected. In this embodiment, the blade 121 has an opening at its center for fixing and connecting the shaft 122. When the blades 121 of these rotor sections 120 rotate, these blades 121 can generate lift, enabling the gyroplane 100 to take off from the ground. Figure 1A In the illustrated embodiment, the rotorcraft 100 may be a quadcopter and includes four rotor sections 120, each rotor section 120 including two rotor blades 121. Specifically, the two rotor blades 121 are disposed in the same rotor section 120, and these rotor blades 121 are respectively connected to both ends of a rotating shaft 122, such as... Figure 1A As shown. However, in other embodiments, the number of rotor blades 121 included in at least one rotor section 120 may be only one, which is not limiting to the present invention. Furthermore, in other embodiments, these rotor sections 120 have at least two rotor sections 120.

[0017] refer to Figure 1AIn this embodiment, the fuselage 110 has a front end portion 111, a rear end portion 112, a top surface 114t, a bottom surface 114b, and two ends of the sides, including a left end portion (not shown) and a right end portion (not labeled). The front end portion 111 and the rear end portion 112 are opposite to each other, while the top surface 114t and the bottom surface 114b are opposite to each other, and the two ends of the sides are opposite to each other, wherein the top surface 114t and the bottom surface 114b are both located between the front end portion 111 and the rear end portion 112. The fuselage 110 also has a reference plane 113, which is defined as passing through the front end portion 111, the rear end portion 112, and the two ends of the sides, and is located between the top surface 114t and the bottom surface 114b. Reference plane 113 is a virtual plane that passes through the foremost and aftmost ends, as well as the two ends of the sides of fuselage 110. The foremost end can be the leading edge of the fore-end 111, and the aftmost end can be the trailing edge of the rear end 112. The maximum length of fuselage 110 is substantially equal to the distance between the foremost and aftmost ends. The central axis (not shown) of fuselage 110 also passes through the foremost and aftmost ends, while the ends of the sides are symmetrically arranged along the central axis of fuselage 110; therefore, the central axis of fuselage 110 is coplanar with reference plane 113. Reference plane 113 also passes through the left end (not shown) and right end (not labeled) of fuselage 110, where the right end and left end are symmetrical about the central axis of fuselage 110. Furthermore, the pivot 122 of each rotor section 120 is tilted towards the fore-end 111. Figure 1A Looking at the same rotating shaft 122, the upper end of the rotating shaft 122 is closer to the front end 111 than the lower end.

[0018] In this embodiment, the angle G11 between the normal direction 113n of the reference plane 113 of the rotorcraft 100 and the gravity direction G1 can be approximately 5 to 20 degrees, while the angle G12 between the axial direction 122a of the rotating shaft 122 and the gravity direction G1 can be approximately 0 to 10 degrees. In other embodiments, the axial direction 122a can be parallel to the gravity direction G1. Therefore, the axial direction 122a of these rotating shafts 122 is not parallel to the normal direction 113n of the reference plane 113, and intersects with the normal direction 113n. Figure 1A For example, the angle A1 between the axial direction 122a of each rotating shaft 122 and the normal direction 113n will be equal to the sum of the angles G11 and G12. Therefore, the angle A1 is approximately between 5 degrees and 30 degrees.

[0019] At least one blade 121 of these rotor sections 120 will be located in a coplanar plane P12, wherein the axial direction 122a is perpendicular to the coplanar plane P12. Figure 1A For example, multiple rotor blades 121 (i.e., ...) on the top surface 114t of the fuselage 110 Figure 1AThe upper rotor blade 121 will be located on a coplanar plane P12, while the other rotor blades 121 adjacent to the bottom surface 114b of the fuselage 110 (i.e., Figure 1A The lower-positioned blades 121 are located on another coplanar plane P12. That is, the blades 121 connected to the same end of the shaft 122 are located on one coplanar plane P12, while the blades 121 connected to the other end of the shaft 122 are located on another coplanar plane P12. These two coplanar planes P12 are parallel to each other, and the blades located on the same coplanar plane P12 are respectively adjacent to the front end 111 and the rear end 112. Furthermore, these coplanar planes P12 are all illusory planes and are not parallel to the reference plane 113. For example, the angle A2 between each coplanar plane P12 and the reference plane 113 can be between 5 and 20 degrees.

[0020] Figure 1B It is the airflow that exerts force on Figure 1A A schematic diagram of a rotorcraft. Please refer to [the diagram]. Figure 1A and Figure 1B Since the angle A1 between the axial direction 122a and the normal direction 113n of the reference plane 113 is approximately between 5 and 30 degrees, and each rotating shaft 122 is tilted towards the forward end 111, the rotorcraft 100 flying forward can generate an angle of attack AA1 between 5 and 20 degrees, which is a positive angle of attack. Figure 1A In the illustrated embodiment, the angle of attack AA1 is substantially equal to the angle between the reference plane 113 and the horizontal plane H1. Thus, the airflow AF1 flowing along the horizontal plane H1 blows towards the bottom surface 114b of the fuselage 110, applying an external force F1 to the bottom surface 114b. This external force F1 can be divided into two components, F11 and F12, along directions parallel and perpendicular to the reference plane 113, respectively. Component F12 is directed perpendicular to the reference plane 113 and is used to generate lift for the fuselage 110. The normal direction of the horizontal plane H1 is perpendicular to the direction of the airflow AF1.

[0021] Figure 1C yes Figure 1A A force diagram illustrating the lift and drag of a rotorcraft. Please refer to [link / reference needed]. Figure 1C The component force F12 generated by the airflow AF1 can be further divided into lift L12 and drag force D12 along the vertical direction (same as the direction of gravity G1) and the horizontal direction (parallel to the horizontal plane H1), respectively. The direction of lift L12 is upward, that is, opposite to the direction of gravity G1 (please refer to...). Figure 1A Therefore, the additional lift L12 generated by the airflow AF1 can help reduce the load on the rotor 100, thereby reducing the burden on the rotor sections 120 and thus helping to extend the flight time.

[0022] Figure 2AThis is a schematic diagram of the airfoil, designated NACA66-018 by the National Advisory Committee on Aeronautics (NACA). Figure 2B yes Figure 2A A schematic diagram showing how the lift coefficient of an airfoil varies with the angle of attack.

[0023] In this embodiment, the fuselage 110 of the rotorcraft 100 may adopt the same or similar shape as the airfoil 20. Generally speaking, according to fluid dynamics, in this embodiment, the lift basically satisfies the following formula (1).

[0024] F = 0.5CρV 2 A………………………………………………(1)

[0025] Where F is lift, and its unit is Newton (N). ρ is air density, and its unit is kilograms per cubic meter (kg / m³). 3 V represents the speed of the airflow AF1 relative to the rotorcraft 100 during flight, and the unit of V is meters per second (m / s). A represents the frontal area, and its unit is square meters (m²). 2 C is the lift coefficient, which changes with the angle of attack, such as... Figure 2B As shown. From Figure 2B Let's look at the graph: when the angle of attack is +5 degrees, C equals 0.5. When the angle of attack is +10 degrees, C equals 1. Conversely, when the angle of attack is -5 degrees, C equals 0.88. When the angle of attack is -10 degrees, C equals -1.

[0026] Formula (1) satisfies the values ​​listed in Table (I) below.

[0027] Table (1)

[0028]

[0029] Therefore, when the fuselage 110 of the rotorcraft 100 adopts the same or similar shape as the airfoil 20, an angle of attack of +5 degrees AA1 can generate an additional 0.72N lift, which is equivalent to 73 grams of gravity, while an angle of attack of -5 degrees AA1 can generate an additional 1.27N negative lift, which is equivalent to 130 grams of gravity; an angle of attack of +10 degrees AA1 can generate an additional 1.44N lift, which is equivalent to 147 grams of gravity, while an angle of attack of -10 degrees AA1 can generate an additional 1.44N negative lift, which is equivalent to 147 grams of gravity.

[0030] Figure 3 This is a schematic diagram illustrating how the flight time of a rotorcraft varies with its payload according to an embodiment of the present invention. Figure 3 The disclosed values ​​were measured during flight according to an embodiment of the present invention, and Figure 3 The horizontal axis represents the load measured by the drone. Existing drones all generate a negative angle of attack during flight, therefore... Figure 3 The loiter time, shown on the vertical axis, is affected not only by the payload but also by the negative lift generated by the negative angle of attack. In other words, Figure 3 The flight delay shown is actually the result of the existing drones being affected by the aforementioned negative lift.

[0031] Please see Figure 3 When the payload of the rotorcraft 100 is 6000 grams, a 5% reduction in weight (equivalent to 300 grams) can increase the flight time by approximately 10%. Assuming that both the existing UAV and the rotorcraft 100 have the same or similar shape to airfoil 20, the rotorcraft 100 with an angle of attack AA1 of +5 degrees generates 203 (73+130) grams more positive lift than the existing UAV with an angle of attack of -5 degrees, resulting in a 6% increase in flight time. Conversely, the rotorcraft 100 with an angle of attack AA1 of +10 degrees generates 294 (147+147) grams more positive lift than the existing UAV with an angle of attack of -10 degrees, resulting in a 10% increase in flight time.

[0032] In summary, in the rotorcraft of the present invention, since the angle between the axial direction of each rotating shaft and the normal direction of the reference plane is between 5 and 30 degrees, a positive angle of attack can be formed when the rotorcraft flies forward, so that the airflow generates additional lift to reduce the rotorcraft's load. Compared with existing UAVs with negative angles of attack, the rotorcraft of the present invention has a longer loiter time and can reduce energy consumption (e.g., electrical energy).

[0033] The above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the invention. All simple equivalent changes and modifications made in accordance with the claims and description of the invention are still within the scope of this patent. Furthermore, no embodiment or claim of the present invention needs to achieve all the objectives, advantages, or features disclosed in the invention. In addition, the abstract and title are merely for assisting in patent document searches and are not intended to limit the scope of the invention.

Claims

1. A rotorcraft, characterized in that, The rotorcraft includes a fuselage and multiple rotor sections, wherein: The fuselage has a front end, a rear end, and two side ends, as well as a reference plane passing through the front end, the rear end, and the two side ends; and The plurality of rotor sections are disposed on the fuselage, wherein each rotor section includes at least one rotor blade and a shaft connecting the at least one rotor blade, and the at least one rotor blade rotates along the axial direction of the shaft to which it is connected. The angle between the axial direction of the rotating shaft and the normal direction of the reference plane is between 5 degrees and 30 degrees; and When the rotorcraft flies forward, the angle between the normal direction of the reference plane and the direction of gravity is between 5 degrees and 20 degrees, the angle between the axis of rotation and the direction of gravity is between 0 degrees and 10 degrees, the rotorcraft forms a positive angle of attack, and the positive angle of attack is between 5 degrees and 20 degrees, which is equal to the angle between the reference plane and the horizontal plane.

2. The rotorcraft as described in claim 1, characterized in that, The plurality of rotor sections surround the fuselage.

3. The rotorcraft as described in claim 1, characterized in that, At least one blade of the plurality of rotor sections is located in a coplanar plane, and the coplanar plane is not parallel to the reference plane.

4. The rotorcraft as described in claim 3, characterized in that, The fuselage also has a top surface located between the front end and the rear end, and the at least one rotor blade located in the coplanar plane is adjacent to the top surface.

5. The rotorcraft as described in claim 3, characterized in that, The at least one rotor blade located in the coplanar plane is adjacent to the front end and the rear end, respectively.

6. The rotorcraft as described in claim 3, characterized in that, The angle between the coplanar plane and the reference plane is between 5 degrees and 20 degrees.

7. The rotorcraft as described in claim 1, characterized in that, Each rotor section includes two blades, and the two blades are disposed in the same rotor section. These blades are respectively connected to both ends of the rotating shaft.

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