Vertical takeoff and landing aircraft

Abstract

A vertical takeoff and landing aircraft according to one embodiment of the present invention is provided with: a pair of right and left rod-shaped support members; a propulsion propeller; a rotor for vertical elevation; and a control unit. The pair of right and left rod-shaped support members extend in the front-rear direction and are provided on both right and left sides. The rotor is disposed at two or more positions in the front-rear direction on each of the rod-shaped support members. Each rotor has a plurality of blades and rotates in a predetermined rotation direction to generate lift. The control unit rotates the rotor during forward flight, and controls the rotational speed of the rotor and the pitch angle of the blade to achieve an advance ratio, which represents the ratio between the flight speed and the tip speed of the rotor, such that the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value.

Description

vertical take-off and landing aircraft

[0001] The present invention relates to vertical take-off and landing aircraft.

[0002] A typical multi-rotor vertical take-off and landing aircraft has multiple rotors that tilt forward during forward flight to simultaneously generate lift and thrust. A combined (lift and cruise) multi-rotor vertical take-off and landing aircraft (see Patent Documents 1 to 5) is equipped with rotors for vertical take-off and landing and propellers, and has fixed wings. During forward flight, the rotors stop rotating, and thrust is generated by the propellers, while lift is generated by the fixed wings.

[0003] Furthermore, Non-Patent Documents 1 and 2 describe a multi-rotor vertical take-off and landing aircraft equipped with four rotors and thrust propellers, which generates lift through the rotation of the rotors during forward flight and propels the aircraft forward with thrust propellers. In such vertical take-off and landing aircraft, flow field interference occurs in which the wake (downwash) generated by the front rotor interferes with the rotor behind it, which can cause a decrease in rotor performance due to flow field interference. Non-Patent Documents 1 and 2 describe improving rotor performance by utilizing the lift offset characteristics of the rotors through variable pitch and variable rotation speed using four rotors.

[0004] Japanese Patent Publication No. 2022-151924 Japanese Patent Publication No. 2022-148991 U.S. Patent Registration No. 10046853 U.S. Patent Publication No. 2019-0127056 Chinese Patent Publication No. 115042968

[0005] Proceedings of 47th European Rotorcraft Forum, Sayama, Y. Hayami, K. , Tanabe, Y. , Sugawara, H. , Kameda, M. , 7-9th Sept. 2021, Paper #95, "PERFORMANCE OF A DUAL-CONTROLLED ROTOR IN LEVEL FLIGHT" Proceedings of the 54th Annual Meeting of the Japanese Society of Fluid Mechanics / 40th Aerospace Numerical Simulation Technology Symposium, Yuto Sayama, Akiaki Sugawara, Yasutada Tanabe, Masaharu Kameda, June 29-July 1, 2022, JSASS-2022-2033-F+A-1B15, "Effect of Aft Rotor Vertical Position on Aerodynamic Control of Multirotors in Forward Flight"

[0006] Multi-rotor VTOL aircraft have issues with high-speed performance because they need to generate lift and thrust simultaneously, while combined multi-rotor VTOL aircraft have issues with the size of the aircraft increasing because they need to generate lift on fixed wings during forward flight.

[0007] In view of the above circumstances, an object of the present invention is to provide a vertical take-off and landing aircraft that can be made smaller and faster.

[0008] To achieve the above object, a vertical take-off and landing aircraft according to one embodiment of the present invention includes a pair of left and right rod-shaped support members, a propulsion propeller, a rotor for vertical lift, and a control unit. The pair of left and right rod-shaped support members extend in the fore-and-aft direction and are provided on both the left and right sides. Two or more rotors are arranged in the fore-and-aft direction on each of the rod-shaped support members, each having a plurality of blades, and rotating in a predetermined rotational direction to generate lift. The control unit rotates the rotor during forward flight and controls the rotation speed of the rotor and the pitch angle of the blades to achieve a forward ratio, which represents the ratio between flight speed and wingtip speed of the rotor, such that the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold.

[0009] In one embodiment of the present invention, a vertical take-off and landing aircraft generates lift during forward flight using a rotor and thrust using a propeller. By generating lift during forward flight using a rotor in this manner, the rotor can provide some or all of the lift during forward flight, enabling a more compact aircraft. Furthermore, providing a propeller enables higher speeds. Furthermore, by controlling the rotor rotation speed during forward flight to achieve a forward ratio (flight speed / wingtip speed) at which the rotor's effective lift-to-drag ratio is equal to or greater than a threshold, the lift distribution can be adjusted so that the rotor generates significant lift on the forward side and little or no lift on the retreating side. This allows the wake distribution (downwash distribution) generated by the rotor to be adjusted, reducing flow field interference, which is the interference of the forward rotor with the rear rotor, and suppressing rotor performance degradation due to flow field interference. Suppressing rotor performance degradation due to flow field interference allows the rotor to more reliably provide some or all of the lift during forward flight, enabling a more compact aircraft.

[0010] The control unit may acquire flight speed information of the vertical take-off and landing aircraft, and use the flight speed information to calculate a range of rotation speeds of the rotor based on first data prepared in advance that indicates the relationship between the effective lift-to-drag ratio of the rotor and the forward advance rate so that the forward advance rate will be such that the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value, use the flight speed information to calculate a range of pitch angles of the blades that will generate the required lift for the rotor within the calculated range of rotor rotation speeds, and determine the rotation speed of the rotor and the pitch angle of the blades within the calculated range of rotor rotation speeds and range of blade pitch angles.

[0011] The control unit may acquire attitude information of the vertical take-off and landing aircraft, and determine the rotation speed of the rotor and the pitch angle of the blades taking the attitude information into consideration.

[0012] The aircraft may further include a storage device that stores the first data prepared in advance and second data indicating the relationship between the rotor rotation speed, the blade pitch angle, and the rotor effective lift-to-drag ratio for each flight speed, wherein the control unit, in calculating the rotor rotation speed, uses the flight speed information and calculates, based on the first data, a range of the rotor rotation speed at which the rotor has an advance rate that makes the rotor effective lift-to-drag ratio equal to or greater than a threshold, and, in calculating the blade pitch angle range, uses the flight speed information and calculates, based on the second data, a range of the blade pitch angle that generates the rotor the lift required for the rotor, within the calculated range of rotor rotation speed.

[0013] The advance rate at which the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold may be 0.5 or greater.

[0014] The rotors are arranged in equal numbers on each of the rod-shaped support members so as to form multiple rotor groups each consisting of a pair of left and right rotors, and the control unit may control the rotation speed of a rotor belonging to one of the multiple rotor groups so that it is different from the rotation speed of a rotor belonging to another rotor group, under the condition that the rotation speed of each of the rotors is within the range of the calculated rotor rotation speed.

[0015] The control unit may control the rotation speed of the rotor and the pitch angle of the blades so that, during forward flight at a flight speed equal to or greater than a predetermined speed, the forward rate is such that the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value.

[0016] The predetermined speed may be 100 km / h (approximately 28 m / s).

[0017] The control unit may rotate the two rotors, which are positioned adjacent to each other in the fore-and-aft direction and whose centers are on the same straight line parallel to the fore-and-aft direction, in opposite directions during forward flight.

[0018] The rotors are arranged in three on each of the rod-shaped support members so that their centers are located on the same straight line parallel to the front-to-rear direction, and the three rotors arranged on the right-side rod-shaped support member are a right-side first rotor, a right-side second rotor and a right-side third rotor arranged in order from front to rear, and the three rotors arranged on the left-side rod-shaped support member are a left-side first rotor, a left-side second rotor and a left-side third rotor arranged in order from front to rear, and the control unit may rotate the right-side first rotor, the right-side third rotor and the left-side second rotor so that their rotation direction is counterclockwise when viewed from above, and rotate the right-side second rotor, the left-side first rotor and the left-side third rotor so that their rotation direction is clockwise.

[0019] Of the two or more rotors arranged on each of the rod-shaped support members, two rotors positioned adjacent to each other in the front-rear direction may be positioned such that the center of one rotor is shifted in the left-right direction from the center of the other rotor.

[0020] The rotors may be arranged in three on each of the rod-shaped support members so that they are positioned at the same vertical position, the three rotors arranged on the right-side rod-shaped support member being a first right-side rotor, a second right-side rotor, and a third right-side rotor arranged in that order from front to rear, and the three rotors arranged on the left-side rod-shaped support member being a first left-side rotor, a second left-side rotor, and a third left-side rotor arranged in that order from front to rear, the second right-side rotor being positioned outward in the left-right direction from the first right-side rotor and the third right-side rotor by a radius of the plane of rotation of the rotors, and the second left-side rotor being positioned outward in the left-right direction from the first left-side rotor and the third left-side rotor by a radius of the plane of rotation of the rotors, and the control unit may rotate the first right-side rotor, the second right-side rotor, and the third left-side rotor so that the rotation direction is counterclockwise when viewed from above, and rotate the third right-side rotor, the first left-side rotor, and the second left-side rotor so that the rotation direction is clockwise.

[0021] Three or more rotors may be arranged on each of the rod-like support members.

[0022] The rotors are arranged in equal numbers on each of the rod-shaped support members so as to form multiple rotor groups each consisting of a pair of left and right rotors, and a rotor belonging to one of the multiple rotor groups may have a different vertical position from rotors belonging to other rotor groups.

[0023] The rotors may be arranged in three on each of the rod-shaped support members so as to be positioned on the same straight line parallel to the front-to-rear direction in a plan view, the three rotors arranged on the right rod-shaped support member being a first right rotor, a second right rotor, and a third right rotor arranged in that order from front to rear, and the three rotors arranged on the left rod-shaped support member being a first left rotor, a second left rotor, and a third left rotor arranged in that order from front to rear, the first right rotor, the second right rotor, the first left rotor, and the second left rotor being positioned at the same vertical position, and the third right rotor and the third left rotor being positioned above the first right rotor, the second right rotor, the first left rotor, and the second left rotor, and the control unit may rotate the first right rotor, the third right rotor, and the second left rotor so that the rotation direction is counterclockwise when viewed from above, and rotate the second right rotor, the first left rotor, and the third left rotor so that the rotation direction is clockwise.

[0024] The rotors may be arranged in three on each of the rod-shaped support members so as to be positioned on the same straight line parallel to the front-to-rear direction in a plan view, the three rotors arranged on the right rod-shaped support member being a first right rotor, a second right rotor, and a third right rotor arranged in that order from front to rear, and the three rotors arranged on the left rod-shaped support member being a first left rotor, a second left rotor, and a third left rotor arranged in that order from front to rear, the first right rotor, the third right rotor, the first left rotor, and the third left rotor being positioned at the same vertical position, the second right rotor and the second left rotor being positioned above the first right rotor, the third right rotor, the first left rotor, and the third left rotor, and the control unit may rotate the first right rotor, the second right rotor, and the third left rotor so that the rotation direction is counterclockwise when viewed from above, and rotate the third right rotor, the first left rotor, and the second left rotor so that the rotation direction is clockwise.

[0025] The aircraft may further include a fuselage and fixed wings coupled to the fuselage and extending in the left-right direction to connect the pair of left and right rod-shaped support members.

[0026] The turbine may further comprise a rotor blade disposed on the fixed blade and generating harmonic vibrations in opposite phase to the vibrations originating from the rotor.

[0027] The rotor may be disposed below the rod-like support member.

[0028] The aircraft may further comprise a vertical tail that extends downward and is disposed at a lower rear part of the rod-like support member, the tip of the vertical tail being located below the plane of rotation of the propulsion propeller.

[0029] The control unit may control the forward-most rotor during forward flight so that its rotation plane is tilted forward relative to the direction of travel, allowing it to function for propulsion in addition to or instead of the propulsion propeller.

[0030] The control unit may control the rotation speed of the forward-most rotor and / or the pitch angle of the blades of the forward-most rotor so that the lift and air resistance of the forward-most rotor are minimized during forward flight.

[0031] The rotors are arranged in equal numbers on each of the rod-shaped support members so as to form multiple rotor groups each consisting of a pair of left and right rotors, and the number of blades of a rotor belonging to one of the multiple rotor groups may be different from that of a rotor belonging to another rotor group.

[0032] According to the present invention, a vertical take-off and landing aircraft that can be made smaller and faster can be provided.

[0033] The effects described here are not necessarily limited to those described herein, and may be any of the effects described in this disclosure.

[0034] 1 is a schematic perspective view of a vertical take-off and landing aircraft according to a first embodiment of the present invention. 2 is a schematic plan view of the vertical take-off and landing aircraft according to the first embodiment. 3 is a schematic side view of the vertical take-off and landing aircraft according to the first embodiment. 4 is a block diagram showing the configuration of a rotor control system of the vertical take-off and landing aircraft according to each embodiment of the present invention. 5 is a diagram for explaining rotor control in the vertical take-off and landing aircraft according to each embodiment of the present invention. 6 is a diagram for explaining rotor control in the vertical take-off and landing aircraft according to each embodiment of the present invention. 7 is a control flow diagram by a control unit in the vertical take-off and landing aircraft according to each embodiment of the present invention. 8 (A) is a conceptual diagram of front and rear rotor flow field interference in a vertical take-off and landing aircraft according to the present invention that does not perform rotation speed control, and 9 (B) is a conceptual diagram of front and rear rotor flow field interference in the vertical take-off and landing aircraft according to each embodiment that performs rotation speed control. 10 is a schematic plan view of a vertical take-off and landing aircraft according to a second embodiment of the present invention. 11 (A) is a conceptual diagram of rotor flow field interference in the vertical take-off and landing aircraft according to the first embodiment, and 12 (B) is a conceptual diagram of rotor flow field interference in the vertical take-off and landing aircraft according to the second embodiment. 13 (A) and 13 (B) are respectively schematic side views of a vertical take-off and landing aircraft according to a third embodiment of the present invention. 1 is a cross-sectional view of a fixed wing for explaining the movement of a rotor blade of a vertical take-off and landing aircraft according to a fourth embodiment of the present invention. (A) and (B) are graphs explaining changes in the vibration of the entire vertical take-off and landing aircraft by harmonically vibrating the rotor blade of the vertical take-off and landing aircraft according to the fourth embodiment. (A) is a schematic side view showing the state of downdraft below the rotor that occurs during take-off and landing in the vertical take-off and landing aircraft according to the first embodiment, and (B) is a schematic side view showing the state of downdraft below the rotor that occurs during take-off and landing in the vertical take-off and landing aircraft according to the fifth embodiment of the present invention. (B) is a schematic side view of a vertical take-off and landing aircraft according to a sixth embodiment of the present invention. (C) is a schematic side view of a vertical take-off and landing aircraft according to a seventh embodiment of the present invention. (C) is a schematic plan view of a vertical take-off and landing aircraft according to a ninth embodiment of the present invention. (A) is a graph showing the sound pressure fluctuations during rotor rotation due to differences in the number of rotor blades, and (B) is a graph showing the sound pressure fluctuations during rotor rotation in each of the first and eighth embodiments. 10A and 10B are conceptual diagrams for explaining a lift offset state of the rotor.

[0035] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same reference numerals will be used to designate components that have already been described, and the description thereof may be omitted.

[0036] First Embodiment

[0037] [Overall configuration of vertical take-off and landing aircraft]

[0038] Fig. 1 is a schematic perspective view of a vertical take-off and landing aircraft according to a first embodiment of the present invention. Fig. 2 is a schematic plan view of the vertical take-off and landing aircraft of the first embodiment. Fig. 3 is a schematic side view of the vertical take-off and landing aircraft of the first embodiment. Fig. 4 is a block diagram showing the configuration of a rotor control system of the vertical take-off and landing aircraft.

[0039] The vertical take-off and landing aircraft 1 is a lift-and-cruise type multi-rotor vertical take-off and landing aircraft equipped with multiple rotors for vertical lifting and lowering (hereinafter simply referred to as "rotors") and propulsion propellers.

[0040] In this specification, the direction of movement of the vertical take-off and landing aircraft 1 when moving horizontally (forward flight) is referred to as the forward direction, and the opposite direction is referred to as the backward direction. Furthermore, the right side of the width direction of the vertical take-off and landing aircraft 1 when viewed from the vertical take-off and landing aircraft 1 while facing forward is referred to as the right direction, and the left side is referred to as the left direction. Furthermore, the vertically upward direction is referred to as the up direction, and the vertically downward direction is referred to as the down direction. The fore-aft direction, the left-right direction, and the up-down direction are perpendicular to each other. Furthermore, in this specification, the plan view of the vertical take-off and landing aircraft 1 refers to the vertical take-off and landing aircraft 1 when viewed from above. Furthermore, the "outer side in the left-right direction" refers to the side away from the longitudinal center line A (see Figure 2 ) that bisects the vertical take-off and landing aircraft 1 in the left-right (width) direction in plan view, and the "inner side in the left-right direction" refers to the side closer to the longitudinal center line A in plan view. Furthermore, the "rotation direction" of the rotor 2 refers to the rotation direction when viewed from a plan view.

[0041] As shown in Figures 1 to 3, the vertical take-off and landing aircraft 1 has a fuselage 3, two fixed wings 4, a pair of left and right rod-shaped support members 5, multiple rotors 2 (six in this embodiment), two propulsion propellers 6, and two vertical tails 7.

[0042] [Components of a vertical take-off and landing aircraft]

[0043] (body)

[0044] The fuselage 3 has a longitudinally elongated shape and a streamlined shape that reduces air resistance during forward flight. A cockpit may be provided in the fuselage 3. The vertical take-off and landing aircraft 1 may be a manned aircraft or an unmanned aircraft controlled by a ground operator via wireless communication.

[0045] (fixed wing)

[0046] The fixed wings 4 have a shape that extends in the left-right direction and connect a pair of left and right rod-shaped support members 5R and 5L, which will be described later. The two fixed wings 4 are located on the front and rear sides of the fuselage 3, respectively, and are connected to the fuselage 3. The fixed wing 4 located at the front is referred to as the front fixed wing 41, and the fixed wing 4 located at the rear is referred to as the rear fixed wing 42, and when there is no need to particularly distinguish between the two, they will be referred to as fixed wings 4. The fixed wings 4 generate a portion of the lift. A pair of left and right moving wings 8 may be provided at the rear end of each fixed wing 4. The moving wings 8 will be described later.

[0047] From the perspective of airframe stability, it is preferable to change the mounting angles of the forward fixed wing 41 and the aft fixed wing 42. For example, the mounting angle of the aft fixed wing 42 may be set approximately 1 degree larger than the mounting angle of the forward fixed wing 41. This makes it possible to increase the lift generated by the fixed wing 4 at the rear of the airframe compared to the front, generating a nose-down moment for the airframe and contributing to improved static stability of the airframe. Furthermore, if the mounting angles of the forward fixed wing 41 and the aft fixed wing 42 were the same, the downwash generated by the forward fixed wing 41 would reduce the lift generated by the aft fixed wing 42; however, by making the mounting angle of the aft fixed wing 42 larger than that of the forward fixed wing 41, it is possible to compensate for and ensure the lift generated by the aft fixed wing 42.

[0048] (Rod-shaped support member)

[0049] The pair of left and right rod-shaped support members 5 have a shape extending in the front-rear direction and are provided on both the left and right sides of the fuselage 3 in a plan view. Of the pair of left and right rod-shaped support members 5, the rod-shaped support member located on the right side is designated by the symbol 5R, and the rod-shaped support member located on the left side is designated by the symbol 5L, but unless there is a need to particularly distinguish between them, they will be referred to as rod-shaped support members 5. In this specification, the rod-shaped support members 5 "extending in the front-rear direction" does not necessarily mean that the rod-shaped support members 5 extend parallel to the front-rear direction, but rather may extend in the front-rear direction as a whole, and may be curved like the rod-shaped support member 5A of the second embodiment described below. In this embodiment, the rod-shaped support members 5 have a shape extending in a straight line parallel to the front-rear direction.

[0050] The right side rod-shaped support member 5R is fixed to the right end side of the front fixed wing 41 and the right end side of the rear fixed wing 42. The left side rod-shaped support member 5L is fixed to the left end side of the front fixed wing 41 and the left end side of the rear fixed wing 42. The rod-shaped support member 5 supports the rotor 2 at its upper part, supports the vertical stabilizer 7 at its lower rear part, and supports the propulsion propeller 6 at its rear part.

[0051] (Rotor)

[0052] Two or more rotors 2 are arranged in the front-rear direction on each of the pair of left and right rod-shaped support members 5R and 5L. "Two or more rotors are arranged in the front-rear direction" includes a configuration in which two or more rotors are arranged on the same straight line parallel to the front-rear direction, as well as a configuration in which two or more rotors are arranged on a curved line extending in the front-rear direction, as long as two or more rotors are arranged in the front-rear direction overall.

[0053] In this embodiment, three rotors 2 are arranged on each rod-shaped support member 5, for a total of six rotors 2. The centers of the three rotors 2 arranged on each rod-shaped support member 5 are located on the same straight line parallel to the fore-aft direction. The centers of each rotor 2 are located at the same distance from the longitudinal center line A in the left-right direction, and are also at the same position in the up-down direction. By arranging the rotors 2 on the same straight line in this way, the lateral width (left-right dimension) of the vertical take-off and landing aircraft 1 can be reduced.

[0054] The same number of rotors 2 are arranged on the top of each rod-shaped support member 5. The three rotors 2 arranged on the right rod-shaped support member 5R are referred to, from front to rear, as the first right rotor 21R, the second right rotor 22R, and the third right rotor 23R. The three rotors 2 arranged on the left rod-shaped support member 5L are referred to, from front to rear, as the first left rotor 21L, the second left rotor 22L, and the third left rotor 23L. When there is no need to particularly distinguish between them, they are referred to as rotors 2. The first right rotor 21R and the first left rotor 21L, the second right rotor 22R and the second left rotor 22L, and the third right rotor 23R and the third left rotor 23L are located at the same position in the fore-and-aft direction and form pairs. In other words, the vertical take-off and landing aircraft 1 has three rotor groups, each consisting of a pair of left and right rotors 2. The rotor group consisting of the first right rotor 21R and the first left rotor 21L is referred to as the first rotor group 210, the rotor group consisting of the second right rotor 22R and the second left rotor 22L is referred to as the second rotor group 220, and the rotor group consisting of the third right rotor 23R and the third left rotor 23L is referred to as the third rotor group 230. When there is no need to distinguish between the two rotors 2 belonging to the first rotor group 210 as the first right rotor 21R and the first left rotor 21L, they will be referred to as the first rotors 21. The same applies to the second rotor group 220 and the third rotor group 230.

[0055] The rotors 2 are rotors for vertical ascent and descent. Each rotor 2 rotates in a predetermined direction to generate lift (upward thrust) during vertical ascent, vertical descent, and hovering (stopping in mid-air). Furthermore, each rotor 2 does not stop rotating during forward flight (horizontal flight) but continues to rotate to generate lift. Thus, in this embodiment and each embodiment described below, the rotor 2, together with the fixed wing 4, generates lift during forward flight. Furthermore, the rotation speed of the rotor 2 and the pitch angle of the blades 25 are controlled individually for each rotor 2. The rotation direction of the rotor 2 is set according to the rotor's position.

[0056] In this embodiment and each of the following embodiments, the rotor is used to generate lift during forward flight, eliminating the need to rely on fixed wings for overall aircraft lift. This allows the span length (width) of the fixed wings to be reduced, thereby reducing the overall width of the vertical take-off and landing aircraft. Furthermore, as will be described in detail later, in this embodiment and each of the following embodiments, the relationship between the forward rate (flight speed / wingtip speed) and the rotor's effective lift-to-drag ratio is used to control the rotor rotation speed and blade pitch angle, thereby suppressing rotor performance degradation due to flow field interference and improving rotor performance. By improving rotor performance, the proportion of lift generated by the fixed wings in the total aircraft lift can be reduced, enabling the fixed wings and, ultimately, the vertical take-off and landing aircraft to be made smaller. While this embodiment and each of the following embodiments use a vertical take-off and landing aircraft with fixed wings as an example, the present invention can also be applied to vertical take-off and landing aircraft without fixed wings. By generating lift during forward flight solely with the rotor, the fixed wings can be omitted, enabling the vertical take-off and landing aircraft to be made smaller.

[0057] In forward flight, the rear rotor of two adjacent rotors is affected by a slightly downward wake (downwash) generated by the front rotor. This is called flow field interference. Generally, due to flow field interference, the rear rotor needs to increase its rotational power to generate the necessary lift, which reduces the performance of the rear rotor.

[0058] In contrast, in the vertical take-off and landing aircraft of this embodiment and each embodiment described below, the rotor is rotated in a predetermined direction during forward flight, and the rotor rotation speed and blade pitch angle are controlled to achieve a forward rate (flight speed / wingtip speed) at which the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold. This makes it possible to generate the necessary lift for the rotor 2 while minimizing the degradation of rotor performance due to flow field interference. Details will be described later.

[0059] 3 and 4 , each rotor 2 has a motor 28, a hub (not shown) connected to the output shaft of the motor 28, and a plurality of blades 25 attached to the hub. The motor 28 is a power source for rotating the rotor 2. The motor 28, a battery (not shown) that supplies power to the motor 28, and the control unit 10 are provided in the fuselage 3.

[0060] Each rotor 2 has four blades 25. The rotation plane 30 of each rotor 2 is horizontal. One longitudinal end of each blade 25 is attached to the hub. The other longitudinal end of each blade 25 is the tip of the blade 25, which is called the blade tip 27. Each rotor 2 is configured so that the rotation speed is variable and the pitch angle of the blades 25 is variable. The pitch angle of the blade 25 is the angle of the blade surface with respect to the rotation axis of the rotor 2. The number of blades is not limited to four, and may be two or more.

[0061] Here, the lift distribution in the plane of rotation 30 of the rotor 2 will be explained using Figures 19(A) and (B). Figure 19(A) is a plan view of the rotor 2, showing the case where the rotation direction 11 is counterclockwise. Figure 19(B) shows a conceptual lift distribution in the plane of rotation 30 of the rotor 2, taken along line B-B in Figure 19(A), when the vertical take-off and landing aircraft 1 is viewed from in front of the aircraft during forward flight. Reference numeral 33 denotes the center of the plane of rotation 20.

[0062] In the rotor 2 in Figure 19(A), the area filled with fine dots in the right half of the rotation surface 30 is the area where the blades 25 rotate in the forward direction (toward the aircraft body), and is called the "forward side." The plain area in the left half of the rotation surface 30 is the area where the blades 25 rotate in the backward direction (toward the aircraft body), and is called the "reverse side." Note that in a rotor that rotates clockwise, the right half of the rotation surface is the reverse side, and the left half is the forward side.

[0063] During forward flight, each rotor 2 mounted on a vertical take-off and landing aircraft 1 has a different relative speed on the blades 25 on the left and right sides of each rotor 2. On the forward side, the horizontal flight speed (V) and the rotational speed (rΩ) in the rotor radial direction r are combined, resulting in a faster relative speed on the blades. On the retreating side, the horizontal flight speed (V) and the rotational speed (rΩ) cancel each other out, resulting in a slower relative speed. As a result, as shown in FIG. 19(B), the rotor 2 generally generates more lift on the forward side than on the retreating side, creating a disparity in the lift distribution across the entire plane of rotation 30, resulting in the point of application of lift being offset from the center (lift offset state). Note that in this specification, "horizontal flight speed" may also be simply referred to as "flight speed."

[0064] (propeller)

[0065] As shown in Figures 1 to 3, the propulsion propellers 6 are disposed at the rear of each of the pair of left and right rod-shaped support members 5R and 5L. The propulsion propeller 6 disposed on the right rod-shaped support member 5R is referred to as the right propulsion propeller 6R, and the propulsion propeller 6 disposed on the left rod-shaped support member 5L is referred to as the left propulsion propeller 6L. When there is no need to particularly distinguish between the two, they are referred to as propulsion propellers 6. In a plan view, the right first rotor 21R, the right second rotor 22R, the right third rotor 23R, and the right propulsion propeller 6R are positioned on a straight line parallel to the fore-and-aft direction. In a plan view, the left first rotor 21L, the left second rotor 22L, the left third rotor 23L, and the left propulsion propeller 6L are positioned on the same straight line parallel to the fore-and-aft direction.

[0066] As shown in FIGS. 1 and 4 , each propulsion propeller 6 has a motor 68, a hub (not shown) connected to the output shaft of the motor 68, and multiple blades 65 attached to the hub. The motor 68 is a power source for rotating the propulsion propeller 6. The motor 68 and a battery (not shown) that supplies power to the motor 68 are provided in the fuselage 3. Note that the battery installation location is not necessarily limited to within the fuselage. For example, in consideration of the weight of the power wiring, the battery may be located as close to each individual motor as possible. The battery may also be distributed within or below the support member. In this embodiment, each propulsion propeller 6 has four blades 65. The plane of rotation of each propulsion propeller 6 is vertical. The propulsion propeller 6 generates forward thrust through the rotation of the blades 65, enabling the vertical take-off and landing aircraft 1 to move forward (forward flight).

[0067] In the vertical take-off and landing aircraft of this embodiment and each of the embodiments described below, thrust is generated by the propeller 6, and lift is generated by the multiple rotors 2 and fixed wings 4, making it possible to achieve high speeds.

[0068] (vertical tail)

[0069] The vertical stabilizers 7 are connected to the lower rear of each of the pair of left and right rod-shaped support members 5R and 5L. The vertical stabilizer 7 connected to the right rod-shaped support member 5R and extending downward is called the right vertical stabilizer 7R, and the vertical stabilizer 7 connected to the left rod-shaped support member 5L and extending downward is called the left vertical stabilizer 7L. When there is no need to particularly distinguish between the two, they are referred to as vertical stabilizers 7. The vertical stabilizers 7 are responsible for maintaining the lateral stability of the vertical take-off and landing aircraft 1. The vertical stabilizers may be provided extending upward from the top of the rod-shaped support members 5.

[0070] [Control system configuration]

[0071] As shown in FIG. 4 , the vertical take-off and landing aircraft 1 includes a control unit 10 that controls the rotor 2 and the propulsion propeller 6 , a storage device 16 , and sensors 17 .

[0072] (sensors)

[0073] The sensors 17 are composed of various sensors that detect the flight state of the VTOL aircraft 1. The sensors 17 include, for example, a gyro sensor that detects the angle of the aircraft, an acceleration sensor that detects the acceleration of the aircraft, an airspeed indicator, a GPS, etc. From the sensing results of the sensors 17, the attitude angle (pitch, roll, yaw), flight speed, position, etc. of the aircraft are detected. Sensing result information from the sensors 17 is output to the control unit 10.

[0074] (Control unit)

[0075] The vertical take-off and landing aircraft 1 is basically controlled in one of the elevator mode, forward flight mode, and hovering mode. The elevator mode is a control mode when the vertical take-off and landing aircraft 1 ascends or descends vertically. The vertical take-off and landing aircraft 1 ascends vertically at take-off and descends vertically at landing. The forward flight mode is a control mode when the aircraft flies forward while maintaining a horizontal attitude. The forward flight mode further includes a constant rotation speed mode in which the rotor rotation speed is controlled to be constant, and a variable rotation speed mode in which the rotor rotation speed can be changed. The hovering mode is a control mode when hovering. Note that although this embodiment provides an example of ascending or descending vertically, it may also ascend or descend obliquely, like a fixed-wing aircraft.

[0076] The aircraft ascends vertically (or obliquely) in ascending / descending mode, and when it reaches a certain altitude, the propulsion propellers 6 are activated, causing it to transition to forward flight mode. In forward flight mode, it flies in a constant rotor rotation speed mode until it reaches a predetermined flight speed (100 km / h (approximately 28 m / s) in this embodiment). Once the predetermined flight speed (100 km / h in this embodiment) is reached, it transitions to a variable rotation speed mode, and the rotor rotation speed and blade pitch angle are controlled in accordance with the present invention. In landing preparation, the aircraft reduces its flight speed in forward flight mode, and when the flight speed falls below the predetermined flight speed, it switches from the variable rotation speed mode to the constant rotation speed mode, and further gradually reduces the flight speed. It then transitions to ascending / descending mode, descends vertically, and lands. The rotor rotation speed in the variable rotation speed mode in forward flight mode is controlled to be smaller than the rotor rotation speed in the ascending / descending mode and the constant rotation speed mode in forward flight mode.

[0077] The control unit 10 individually controls each rotor 2 and each propeller 6 according to each mode. The control unit 10 controls the rotation speed of the propeller 6 and the like, and controls the flight speed of the vertical take-off and landing aircraft 1. The control unit 10 controls the rotation speed of the rotor 2 and the pitch angle of the blades 25.

[0078] In forward flight mode, when flying forward at a flight speed of 100 km / h or more, the control unit 10 rotates the rotor 2 in a direction corresponding to its position, and uses flight speed information to control the rotation speed of the rotor 2 and the pitch angle of the blades 25 so that the forward rate (flight speed / wingtip speed) is such that the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value.

[0079] Specifically, the control unit 10 uses the flight speed information to calculate a range of rotor rotation speeds based on first data prepared in advance that indicates the relationship between the rotor's effective lift-to-drag ratio and forward advance rate (flight speed / wingtip speed) so that the rotor's effective lift-to-drag ratio is equal to or greater than a threshold. The control unit 10 then uses the flight speed information to calculate a blade pitch angle range that will generate the necessary lift for the rotor within the calculated range of rotor rotation speeds. The control unit 10 then determines the rotation speeds and blade pitch angles of each rotor within the calculated range of rotor rotation speeds and blade pitch angles, and controls the rotor 2 based on the determined rotation speeds of the rotor 2 and pitch angles of the blades 25.

[0080] Data stored in the storage device 16, which will be described later, is used to calculate the range of the rotor rotation speed and the range of the blade pitch angle, and to determine the rotor rotation speed and the blade pitch angle.

[0081] During forward flight, the lift generated by each rotor 2 is controlled so that the aircraft maintains a horizontal attitude. The control unit 10 may determine the rotation speed of the rotor 2 and the pitch angle of the blades 25 so as to maintain a horizontal attitude, taking into account attitude information of the vertical take-off and landing aircraft 1 in addition to the data stored in the storage device 16.

[0082] The flight speed information and attitude information of the vertical take-off and landing aircraft 1 can be acquired using the sensing results of the sensors 17. The flight speed information and attitude information are acquired in real time.

[0083] Furthermore, in forward flight mode, the control unit 10 controls the rotation direction of each rotor in accordance with the arrangement position of the rotor 2. The rotation direction of a rotor is determined in accordance with the downwash distribution of the rotor in front of it so as to reduce flow field interference.

[0084] (Storage device)

[0085] 5 and 6 show examples of data stored in the storage device 16 used for controlling the rotor 2. As shown in FIG. 4, the storage device 16 stores rotation speed calculation data 161 as first data and pitch angle calculation data 162 as second data. FIG. 5 shows the rotation speed calculation data 161. FIGS. 6A and 6B show conceptual pitch angle calculation data 162. The rotation speed calculation data 161 and the pitch angle calculation data 162 are prepared in advance and stored in the storage device 16.

[0086] ((Data for calculating rotation speed))

[0087] The rotation speed calculation data 161 as the first data is used to calculate the range of the rotor rotation speed to minimize the degradation of aerodynamic performance due to flow field interference. The rotation speed calculation data 161 indicates the relationship between the advance rate and the effective lift-to-drag ratio of the rotor.

[0088] The inventors have discovered a correlation between the effective lift-drag ratio of the rotor and the forward forward rate, where, when a vertical take-off and landing aircraft 1 equipped with multiple vertical lift rotors 2 and propulsion propellers 6 is flying at a speed of 100 km / h or more in forward flight, the effective lift-drag ratio of the rotor becomes stable at or above a threshold value when the forward forward rate (flight speed / rotor tip speed) is equal to or greater than a predetermined value (0.5), as shown in the rotation speed calculation data 161 in FIG. 5 .

[0089] By controlling the rotor rotation speed based on the rotation speed calculation data 161 using flight speed information, it is possible to adjust the lift distribution (lift distribution) generated on the rotation plane 30 of the rotor 2, and thus the downwash distribution. By controlling the rotor 2 at a rotor rotation speed that results in an advance rate (0.5 or greater) that makes the rotor's effective lift-to-drag ratio equal to or greater than a threshold, it is possible to adjust the lift distribution (reference numeral 18 in FIG. 8 ) and thus the downwash distribution (reference numeral 12 in FIG. 8 ) so that large lift is generated on the advance side of the rotation plane 30 of the rotor 2 and no lift or nearly so on the retreat side. Then, by controlling the rotor rotation direction in consideration of the downwash distribution and the rotor's position, it is possible to suppress deterioration of rotor performance due to flow field interference and minimize deterioration of aerodynamic performance.

[0090] As shown in FIG. 5, the rotation speed calculation data 161 is a ratio of the effective lift-drag ratio (L / D) of the rotor 2 to the advance rate (μ). Ｅ ) data. The forward speed (μ) is expressed as the ratio of the horizontal flight speed (V) divided by the tip speed RΩ (where R is the rotor radius and Ω is the rotational speed). The tip speed is the speed of the tip 27 corresponding to the tip of the blade 25.

[0091] The effective lift-drag ratio of rotor 2 (L / D Ｅ ) is the lift force L and the effective drag force D Ｅ The effective lift-to-drag ratio of the rotor 2 is an index showing the performance of the rotor, and the larger the value of the effective lift-to-drag ratio, the smaller the air resistance, which indicates higher energy efficiency and better rotor performance. Ｅ is defined as follows:

[0092] D Ｅ = P / V - X = P / V + D (P is rotor rotational power, V is horizontal flight speed, X is thrust, and D is drag.)

[0093] As shown in the rotation speed calculation data 161 in Figure 5, when the forward advance ratio (flight speed / rotor tip speed) is in the range of 0.2 or greater, the effective lift-to-drag ratio tends to increase as the forward advance ratio increases. Furthermore, when the forward advance ratio is 0.5 or greater, the rotor's effective lift-to-drag ratio stabilizes in the range of approximately 6.0 to 6.5. In other words, by controlling the rotor 2 at a rotor rotation speed that results in a forward advance ratio (0.5 or greater) that causes the rotor's effective lift-to-drag ratio to be equal to or greater than a threshold value (the threshold value is 6.0 in the example shown in Figure 5), changes in rotor performance are reduced, and rotor performance is stabilized in a good state. A higher forward advance ratio for a certain flight speed means a lower rotor rotation speed, and reducing the rotation speed can increase the rotor's effective lift-to-drag ratio.

[0094] Here, the "threshold" in "the rotor's effective lift-drag ratio is equal to or greater than the threshold" refers to the value at which the rotor's effective lift-drag ratio begins to stabilize. In the example shown in FIG. 5, the threshold is 6.0. Note that this threshold can be changed depending on the position of the rotor 2. For example, when the rotors are arranged on the same line as in this embodiment, the threshold of the rotor's effective lift-drag ratio is lower for the third rotor 23 than for the first rotor 21, the second rotor 22, and the third rotor 23. However, the graph (see FIG. 5) showing the correlation between the advance rate and the rotor's effective lift-drag ratio has a similar shape and changes in the same manner. For both rotors, the rotor's effective lift-drag ratio becomes equal to or greater than the threshold, i.e., rotor performance stabilizes, when the advance rate is 0.5 or greater. Note that the threshold of the effective lift-drag ratio is lower for the third rotor 23 because the third rotor 23 is affected by the downwash of the first rotor 21 and the second rotor 22, as shown in FIG. 10(A).

[0095] The rotation speed range of each rotor 2 can be calculated using the same rotation speed calculation data 161, but the memory device 16 may store, for example, separate rotation speed calculation data 161 for the first rotor 21, the second rotor 22, and the third rotor 23.

[0096] ((Data for calculating pitch angle))

[0097] The pitch angle calculation data 162 as the second data is used to calculate the range of the pitch angle of the blades 25 and to determine the rotation speed of the rotor 2 and the pitch angle of the blades 25. The pitch angle calculation data 162 is data that indicates the relationship between the rotation speed of the rotor 2, the pitch angle of the blades 25, and the effective lift-to-drag ratio of the rotor 2.

[0098] The control unit 10 uses the flight speed information and, based on the pitch angle calculation data 162, calculates the pitch angle range of the blades 25 that will generate the lift required for the rotor 2, within the range of rotor rotation speeds calculated using the rotation speed calculation data 161. Then, the control unit 10 determines the rotation speed of the rotor 2 and the pitch angle of the blades 25 so that the effective lift-to-drag ratio of the rotor is optimized within the calculated range of rotor rotation speeds and pitch angles.

[0099] The pitch angle calculation data 162 includes data showing the relationship between the blade pitch angle (blade pitch angle) and the rotor rotation speed shown in FIG. 6A and data showing the relationship between the blade pitch angle and the rotor's effective lift-to-drag ratio shown in FIG. 6B. The horizontal axis showing the blade pitch angle in the data shown in FIG. 6A corresponds to the horizontal axis showing the blade pitch in the data shown in FIG. 6B. FIG. 6A shows the relationship between the pitch angle and the rotation speed that can generate the same lift. For example, even if the rotor rotation speed is changed, the same lift can be obtained by changing the blade pitch angle according to the rotation speed based on FIG. 6A. The data (pitch angle calculation data 162) showing the relationship between the rotor rotation speed, the blade pitch angle, and the rotor's effective lift-to-drag ratio shown in FIGS. 6A and 6B differs for each flight speed. The storage device 16 pre-stores the pitch angle calculation data 162 for each flight speed.

[0100] (Details of control by the control unit)

[0101] 2 and 10A, how the rotation direction of the rotor 2 is controlled will be explained. Then, how the control unit 10 determines the rotation speed of the rotor 2 and the pitch angle of the blades 25 used to control the rotor 2 during forward flight at a flight speed equal to or greater than a predetermined speed (100 km / h) will be explained using FIGS. 5, 6, and 8 along with the control flow in FIG. 7.

[0102] Figure 10(A) is a right-side partial plan view of the vertical take-off and landing aircraft 1 of this embodiment for explaining the relationship between the rotation direction and flow field interference. Figure 7 is a control flow diagram by the control unit 10. Figures 8(A) and 8(B) are conceptual diagrams for explaining the flow field interference of two rotors positioned adjacent to each other in the longitudinal direction on the same straight line parallel to the longitudinal direction, showing the lift distribution and downwash distribution generated on the rotor rotation plane. In the explanation using Figures 8(A) and 8(B), the rotor positioned forward of the two rotors 2 (hereinafter referred to as the forward rotor) will be designated by the symbol 2F, and the rotor positioned aft (hereinafter referred to as the aft rotor) will be designated by the symbol 2R.

[0103] Figure 8(A) is a conceptual diagram of flow field interference for a multi-rotor aircraft without propellers as a comparative example, showing a case where rotor speed control according to the present invention is not performed. In a multi-rotor aircraft, the rotors tilt forward during forward flight, and the rotors must simultaneously generate lift and thrust, resulting in a forward flight rate of approximately 0.2 to 0.4. Figure 8(A) shows a conceptual diagram of flow field interference when, for example, the forward flight rate is approximately 0.3 and the rotor effective lift-to-drag ratio is approximately 4.

[0104] 8(B) is a conceptual diagram of flow field interference when controlling the rotor rotation speed according to the present invention, where the forward rate is 0.5 and the rotor effective lift-to-drag ratio is approximately 6. The vertical take-off and landing aircraft according to this embodiment and each of the embodiments described below are equipped with a propeller 6, which provides thrust during forward flight, with the rotors 2 contributing only to the generation of lift. Therefore, during forward flight at a flight speed equal to or greater than a predetermined speed, the rotation speed of the rotor 2 can be changed to decrease, thereby increasing the forward rate.

[0105] (Rotation direction control)

[0106] 10A , when the centers of two rotors 2 adjacent in the longitudinal direction are located on the same straight line parallel to the longitudinal direction in a plan view, the control unit 10 controls the two rotors 2 to rotate in opposite directions. In the vertical take-off and landing aircraft 1, the two rotors 2 adjacent in the longitudinal direction are the first right rotor 21R and second right rotor 22R, the second right rotor 22R and third right rotor 23R, the first left rotor 21L and second left rotor 22L, and the second left rotor 22L and third left rotor 23L.

[0107] 2 and 10A, the first right rotor 21R and the third right rotor 23R are controlled to rotate counterclockwise, and the second right rotor 22R is controlled to rotate clockwise. Similarly, the first left rotor 21L and the third left rotor 23L are controlled to rotate clockwise, and the second left rotor 22L is controlled to rotate counterclockwise.

[0108] In a plan view of the vertical take-off and landing aircraft 1, the rotation direction of the rotors is determined according to the position of each rotor, such that the forward side (left half) of the right second rotor 22R is located immediately behind the retreating side (left half) of the right first rotor 21R, and the forward side (right half) of the right third rotor 23R is located immediately behind the retreating side (right half) of the right second rotor 22R. Similarly, the rotation direction of the rotors is determined according to the position of each rotor, such that the forward side (right half) of the left second rotor 22L is located immediately behind the retreating side (right half) of the left first rotor 21L, and the forward side (left half) of the left third rotor 23L is located immediately behind the retreating side (left half) of the left second rotor 22L.

[0109] Control of the rotation direction when the centers of two rotors 2 adjacent in the longitudinal direction are shifted in the lateral direction will be described in a second embodiment.

[0110] (Determining rotor speed and blade pitch angle)

[0111] When the forward flight mode is entered and the aircraft is flying forward at a flight speed equal to or greater than a predetermined speed (100 km / h), the control unit 10 uses flight speed information based on the sensing results acquired by the sensors 17 to calculate a range of rotor rotation speeds at which the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value, based on the rotation speed calculation data 161 in Fig. 5 (ST1). Specifically, in the example shown in Fig. 5, the control unit 10 uses the flight speed information to calculate a range of rotor rotation speeds based on the rotation speed calculation data 161, such that the forward ratio is 0.5 or greater, at which the effective lift-to-drag ratio of the rotor is 6 or greater.

[0112] By controlling the rotors 2 at the rotation speed calculated in this manner, it is possible to adjust the lift distribution 18 in the plane of rotation 30 of each rotor 2 so that large lift is generated on the advancing side and no lift or nearly so is generated on the retreating side, as shown in Figure 8(B). Therefore, it is possible to adjust the downwash distribution 12 so that large downwash is generated behind the advancing side of the front rotor 2F and nearly no downwash is generated behind the retreating side of the front rotor 2F.

[0113] By adjusting the lift distribution and downwash distribution on the rotor rotation surfaces in this way and controlling the rotor rotation directions as described above, the forward side of the rotation surface 30 of the aft rotor (e.g., right second rotor 22R) is positioned behind the backward side of the rotation surface 30 of the forward rotor (e.g., right first rotor 21R) in two rotors adjacent in the longitudinal direction. As a result, the forward side of the rotation surface of the aft rotor, where lift is mainly generated, is less susceptible to the downwash from the forward rotor, thereby reducing flow field interference.

[0114] 10A, the third rotor 23 is affected by the downdraft of the first rotor 21 and the second rotor 22 located in front of it. However, by reversing the rotational directions of the second rotor 22 and the third rotor 23, the third rotor 23 is affected by the downdraft of the first rotor 21, which rotates in the same direction, but is less affected by the downdraft of the second rotor 22, thereby reducing flow field interference.

[0115] In this way, in forward flight mode, the rotor rotation speed range is such that the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value, and the rotation direction of each rotor is controlled according to the rotor's position, so there is no need to increase the rotor rotational power of the rear rotor 2R to generate the necessary lift due to the effect of downwash, and it is possible to suppress the deterioration of rotor performance of the rear rotor 2R due to flow field interference, thereby minimizing the deterioration of aerodynamic performance.

[0116] In contrast, as shown in Figure 8A, in a comparative example in which the rotor speed control of this embodiment is not performed, when the forward advance ratio is 0.3, for example, large lift is likely to be generated even on the retreating side of the front rotor 2F, and in downwash distribution 12, large downwash occurs behind the retreating side of the front rotor 2F, and this downwash significantly affects the forward advance side of the rear rotor 2R. As a result, in order to generate the necessary lift for the rear rotor 2R, it becomes necessary to increase the rotor rotational power of the rear rotor 2R, which reduces rotor performance.

[0117] Next, the control unit 10 acquires attitude information of the aircraft based on the sensing results of the sensors 17 (ST2).

[0118] Next, the control unit 10 determines, for each rotor 2, the lift required to keep the aircraft in a horizontal attitude based on the attitude information, and calculates the range of pitch angles of the blades 25 required to obtain the required lift (ST3). In detail, the control unit 10 uses the flight speed information to calculate, for each rotor 2, the blade pitch angle range corresponding to the range of rotor rotation speeds calculated in ST1, within the range in which the rotor 2 can obtain the required lift, based on the data showing the relationship between rotation speeds and blade pitch angles shown in Figure 6(A).

[0119] Next, the control unit 10 determines, for each rotor 2, a blade pitch angle that maximizes the rotor's effective lift-to-drag ratio within the calculated blade pitch angle range, based on the data shown in Figure 6(B), and determines the rotor rotation speed according to the determined blade pitch angle (ST4). Each rotor 2 is controlled by the determined rotor rotation speed and blade pitch angle. The rotor 2 generates the required lift by adjusting the blade pitch angle, and is adjusted so that the air resistance of the rotor 2 is reduced at a low rotation speed.

[0120] Here, when determining the rotor rotation speed and blade pitch angle, if the rotation speeds of the rotors 2 are set to be the same, noise may be generated due to vibrations originating from the rotors 2. Therefore, from the perspective of noise reduction, the rotation speeds of the rotors 2 may be shifted to an extent that does not cause sound resonance within the range of the rotor 2 rotation speeds calculated in ST1.

[0121] Note that control of the rotor rotation speed and blade pitch angle using the rotation speed calculation data 161 and pitch angle calculation data 162 is preferably used when the flight speed is 100 km / h or higher. If the above control is performed when the flight speed is less than 100 km / h, it is difficult for the rotor to generate sufficient lift.

[0122] As described above, a vertical take-off and landing aircraft is equipped with a rotor that generates lift during forward flight and a propeller, and rotor performance is improved by suppressing deterioration of rotor performance due to flow field interference, making it possible to reduce the size and increase the speed.

[0123] It is also possible to use a vertical take-off and landing aircraft that does not have fixed wings 4, and by controlling the rotor rotation speed and blade pitch angle as described above, it is possible to suppress the deterioration of rotor performance due to flow field interference, as in this embodiment, and to make it possible to reduce the size.

[0124] The vertical take-off and landing aircraft of this embodiment and each embodiment described below have six rotors 2. This improves redundancy and safety. Even if one rotor 2 fails, the remaining rotors 2 can continue to provide lift. If one rotor 2 fails, the rotor 2 paired with the failed rotor 2 may be stopped and four rotors 2 may be used, or the remaining five rotors 2 may continue to rotate.

[0125] The vertical take-off and landing aircraft of this embodiment and each embodiment described below have six rotors 2, but the present invention can be applied to any number of rotors, as long as there are four or more rotor groups, each consisting of a pair of two rotors on the left and right, arranged in the fore-and-aft direction.

[0126] Other embodiments will be described below, focusing on the differences from the first embodiment. Similar components will be assigned similar reference numerals, and descriptions thereof may be omitted. In each of the following embodiments, as in the first embodiment, the rotor rotation speed and blade pitch angle are controlled using the relationship between the forward movement rate and the rotor's effective lift-to-drag ratio during forward flight at a flight speed equal to or greater than a predetermined speed.

[0127] Second Embodiment

[0128] A vertical take-off and landing aircraft 1A according to the second embodiment will be described with reference to Fig. 9. Fig. 9 is a plan view of the vertical take-off and landing aircraft 1A.

[0129] In the first embodiment, the rod-shaped support members 5 have a shape that extends linearly in parallel in the fore-and-aft direction, but as in a vertical take-off and landing aircraft 1A shown in Fig. 9, the pair of left and right rod-shaped support members 5A and 5B may have a curved shape that curves in a plan view and extends in the fore-and-aft direction. In a plan view, the right rod-shaped support member 5AR and the left rod-shaped support member 5AL each have a curved shape with the center in the fore-and-aft direction convex outward in the left-and-right direction.

[0130] The centers of the three rotors supported by the pair of left and right rod-shaped support members 5AR and 5AL are aligned in the front-rear direction, but are not located on a straight line parallel to the front-rear direction, and are positioned offset in the left-right direction along a curve. As shown in Figure 9, in a plan view, the right second rotor 22R is positioned outward in the left-right direction from the right first rotor 21R and the right third rotor 23R by the radius of the rotation plane 30. The right first rotor 21R and the right third rotor 23R are positioned at the same distance from the longitudinal center line A in the left-right direction. Similarly, the left second rotor 22L is positioned outward in the left-right direction from the left first rotor 21L and the left third rotor 23L by the radius of the rotation plane 30. The left first rotor 21L and the left third rotor 23L are positioned at the same distance from the longitudinal center line A in the left-right direction. In this embodiment, as in the first embodiment, the first right rotor 21R and the first left rotor 21L, the second right rotor 22R and the second left rotor 22L, and the third right rotor 23R and the third left rotor 23L are paired, respectively, to form a first rotor group 210, a second rotor group 220, and a third rotor group 230. The six rotors 2 are positioned at the same position in the vertical direction.

[0131] The rotation direction of each of the six rotors 2 will be described. When, as in this embodiment, the centers of two rotors 2 that are the same in the up-down direction and adjacent in the fore-and-aft direction are shifted in the left-right direction by the radius of the rotor rotation plane 30, the rotation direction of the rotors 2 is controlled to achieve the following (1) and (2). In this embodiment, the two rotors 2 adjacent in the fore-and-aft direction are the first right rotor 21R and the second right rotor 22R, the second right rotor 22R and the third right rotor 23R, the first left rotor 21L and the second left rotor 22L, and the second left rotor 22L and the third left rotor 23L. Of the two rotors adjacent in the fore-and-aft direction, the rotor located at the front is called the front rotor, and the rotor located at the rear is called the rear rotor.

[0132] (1) When the rear rotor is positioned outward in the left-right direction by the radius of the plane of rotation of the front rotor, the rotation directions of the front and rear rotors are controlled to be the same so that the front rotor is not positioned in front of the forward side of the plane of rotation 30 of the rear rotor, and the backward side of the plane of rotation 30 of the rear rotor is positioned behind the forward side of the plane of rotation 30 of the front rotor. By controlling in this way, the rear rotor is less susceptible to the downwash effect of the front rotor on the forward side of its plane of rotation 30, where lift is mainly generated.

[0133] (2) When the rear rotor is positioned laterally inward of the front rotor by the radius of the plane of rotation, the rotation directions of the front and rear rotors are controlled to be opposite to each other so that the front rotor is not positioned immediately in front of the forward side of the plane of rotation 30 of the rear rotor, but the retreating side of the plane of rotation 30 of the rear rotor is positioned behind the retreating side of the plane of rotation 30 of the front rotor. By controlling in this way, the rear rotor is less susceptible to the downwash effect of the front rotor on the forward side of its plane of rotation 30, where lift is mainly generated.

[0134] In this embodiment, as shown in Figure 9, the first right rotor 21R and the second right rotor 22R rotate counterclockwise, and the third right rotor 23R rotates clockwise. The first left rotor 21L and the second left rotor 22L are controlled to rotate clockwise, and the third left rotor 23L rotates counterclockwise. By controlling the rotation direction in this manner, each rotor is positioned so that no other rotor is located in front of the forward side of its own rotation plane, or even if another rotor is located in front of it, the retreating side of the other rotor is located in front of the forward side of its own rotation plane.

[0135] 9 and 10(B), the positional relationship and rotational direction relationship between the right first rotor 21R and the right second rotor 22R, and the positional relationship and rotational direction relationship between the left first rotor 21L and the left second rotor 22L satisfy the above (1). By controlling the rotational direction of the rotors in accordance with their positions in this way, the second rotor 22 (rear rotor) is less susceptible to downwash from the first rotor 21 (front rotor) on the forward direction side of its rotation plane 30 where lift is mainly generated.

[0136] 9 and 10(B), the positional relationship and rotational direction relationship between the right second rotor 22R and the right third rotor 23R, and the positional relationship and rotational direction relationship between the left second rotor 22L and the left third rotor 23L satisfy the above condition (2). By controlling the rotational direction of the rotors in accordance with their positions in this way, the third rotor 23 (rear rotor) is less susceptible to downwash from the second rotor 22 (front rotor) on the forward direction side of its rotation plane 30 where lift is mainly generated.

[0137] Furthermore, as shown in Figures 9 and 10(B) , in the vertical take-off and landing aircraft 1A, the rotation direction is controlled as described above, so that the right first rotor 21R and the right third rotor 23R rotate in opposite directions. The right first rotor 21R and the right third rotor 23R are arranged so that their centers are adjacent to each other on the same straight line parallel to the fore-and-aft direction. In this arrangement, the right third rotor 23R is affected by the downdraft of the right first rotor 21R. However, in this embodiment, the rotation direction is controlled so that the retreating side, where the right first rotor 21R generates no or nearly no lift, is located in front of the forward moving side of the right third rotor 23R. Therefore, the right third rotor 23R is less affected by the downdraft of the right first rotor 21R. Therefore, the right third rotor 23R is less affected by the downdraft of both the right first rotor 21R and the right second rotor 22R, which are located in front of it. The same applies to the left side.

[0138] In this way, in this embodiment, some of the rotors are positioned further outward in the left-right direction than the other rotors, so the width size of the aircraft is larger than in the first embodiment, but as described above, all six rotors 2 can be positioned to avoid flow field interference, thereby improving rotor performance.

[0139] Third Embodiment

[0140] Vertical take-off and landing aircraft 1B and 1C according to the third embodiment will be described using Figure 11. Figure 11(A) is a schematic side view of vertical take-off and landing aircraft 1B, and Figure 11(B) is a schematic side view of vertical take-off and landing aircraft 1B. As with the first embodiment, both vertical take-off and landing aircraft 1B and 1C have a pair of left and right rod-shaped support members 5 that are linear and parallel to the fore-and-aft direction, and the three rotors provided on each rod-shaped support member 5 are positioned on the same straight line that is parallel to the fore-and-aft direction in a plan view.

[0141] In the first embodiment, the six rotors 2 are positioned at the same vertical position, but as shown in Figures 11(A) and (B), the positions may be different in the vertical direction. By changing the height of the rear rotor of two rotors adjacent in the longitudinal direction so that it is higher than the front rotor, the influence of flow field interference caused by the downflow of the front rotor on the rear rotor can be reduced, the rotation direction of the rear rotor is not limited, and the design range is widened. The rear rotor is positioned higher than the front rotor by approximately the radius of the rotation plane 30 of the rotor 2.

[0142] [Vertical Take-Off and Landing Aircraft 1B]

[0143] In the vertical take-off and landing aircraft 1B shown in Figure 11(A), the first rotor 21 and the second rotor 22 are positioned at the same vertical position. The third rotor 23 is positioned higher than the first rotor 21 and the second rotor 22 in the vertical direction. The height of the third rotor 23 may be adjusted by adding a structure 29 to the rod-shaped support member 5 to change the rotor height. When adding the structure 29, it is preferable that the structure 29 have a streamlined shape to avoid increasing air resistance. As with the first embodiment, it is preferable that the rotation direction of each rotor 2 be determined taking into account the downwash distribution based on the conceptual diagram of flow field interference between the front and rear rotors as shown in Figure 8(B).

[0144] The three rotors 2 arranged on each rod-shaped support member 5 are positioned on the same straight line parallel to the front-to-rear direction in a plan view, and as shown in Figure 11 (A), the third rotor 23 is positioned higher than the first rotor 21 and the second rotor 22, so that the third rotor 23, which is third from the front, is less susceptible to the downdraft caused by the first rotor 21 and the second rotor 22 located in front of it. Furthermore, by reversing the rotation directions of the first rotor 21 and the second rotor 22, which are adjacent to each other in the front-to-rear direction and are positioned at the same vertical position, as with the first rotor 21 and the second rotor 22 in the first embodiment, the second rotor 22 is less susceptible to the downdraft caused by the first rotor 21.

[0145] As described above, all rotors of the vertical take-off and landing aircraft 1B are configured to avoid flow field interference. By varying the vertical positions of the rotors and controlling the rotation direction according to the rotor placement position, flow field interference can be reduced.

[0146] [Vertical Take-Off and Landing Aircraft 1C]

[0147] 11(B), the first rotor 21 and the third rotor 23 are positioned at the same vertical position. The second rotor 22 is positioned higher in the vertical direction than the first rotor 21 and the third rotor 23. The rotor height of the second rotor 22 may be adjusted by adding a rotor height adjusting structure 29 to the rod-shaped support member 5.

[0148] When the three rotors 2 arranged on each rod-shaped support member 5 are positioned on the same straight line parallel to the front-to-rear direction in a planar view, and the second rotor 22 is positioned higher than the first rotor 21 and the third rotor 23 as shown in Figure 11 (B), the rotation direction of the second rotor 22 on each rod-shaped support member 5 is the same as that of the first rotor 21, and the rotation direction of the third rotor 23 is the opposite rotation direction to that of the second rotor 22.

[0149] In the example shown in Figure 11 (B), the rotation direction of the right-side first rotor 21R and the right-side second rotor 22R is counterclockwise, the rotation direction of the right-side third rotor 23R is clockwise, the rotation direction of the left-side first rotor 21L and the left-side second rotor 22L is clockwise, and the rotation direction of the left-side third rotor 23L is counterclockwise.

[0150] Since the second rotor 22 is positioned higher than the first rotor 21 , the second rotor 22 is less susceptible to the downdraft caused by the first rotor 21 .

[0151] Furthermore, by setting the rotation direction of each rotor 2 as described above, the second rotor 22 and the third rotor 23 rotate in opposite directions. In other words, the forward-moving side (left half of the rotation plane) of the rotation plane 30 of the right-side third rotor 23R is located behind the retreating side (left half of the rotation plane) of the rotation plane of the right-side second rotor 22R. Because the rotors are controlled to achieve a lift distribution in which no lift is generated or a state close to it on the retreating side, the downwash caused by the right-side second rotor 22R is distributed in a state in which no downwash is generated or a state close to it behind the retreating side of the rotation plane 30 of the right-side second rotor 22R, making the right-side third rotor 23R less susceptible to the downwash of the right-side second rotor 22R. The same is true on the left side.

[0152] Furthermore, by setting the rotation direction of each rotor 2 as described above, the first rotor 21 and the third rotor 23, whose centers are adjacent to each other in the longitudinal direction on the same straight line parallel to the longitudinal direction, are positioned at the same vertical position but rotate in opposite directions. In other words, the forward-moving side (left half of the rotation plane) of the rotation plane 30 of the right third rotor 23R is located behind the retreating side (left half of the rotation plane) of the rotation plane of the right first rotor 21R. Because the rotors are controlled to achieve a lift distribution that generates no or nearly no lift on the retreating side, the downdraft generated by the right first rotor 21R is distributed in a way that generates no or nearly no downdraft behind the retreating side of the rotation plane 30 of the right first rotor 21R, making the right third rotor 23R less susceptible to the downdraft of the right first rotor 21R. Therefore, the right third rotor 23R is less susceptible to the downdraft of the right first rotor 21R and right second rotor 22R, which are located in front of it. The same is true on the left side.

[0153] As described above, all rotors of the vertical take-off and landing aircraft 1C are configured to avoid flow field interference. By varying the vertical positions of the rotors and controlling the rotation direction according to the rotor placement position, flow field interference can be reduced.

[0154] Fourth Embodiment

[0155] Figure 12 is a schematic cross-sectional view of a stator 4 provided with a rotor blade 8, taken along line XII-XII in Figure 1. Figure 13(A) is a conceptual diagram showing vibrations originating from the rotor (shown by thin solid lines) and vibrations of the rotor blade alone (shown by dashed lines), and Figure 13(B) is a conceptual diagram showing vibrations originating from the rotor (shown by thin solid lines) and vibrations resulting from the combination of vibrations originating from the rotor and harmonic vibrations caused by the rotor blade (shown by thick solid lines). In Figures 13(A) and (B), each vibration corresponds to fluctuations in lift generated in the stator 4.

[0156] Vibrations originating from the rotor 2 are generated by a lift distribution in which the lift is greater on the forward direction of the rotation plane 30 of the rotor 2, causing vibrations in the airframe. As shown in FIG. 12 , in this embodiment and other embodiments, the rotor blades 8 may be configured to move up and down so as to generate harmonic vibrations in the opposite phase to the vibrations originating from the rotor 2. As shown in FIG. 13(A) , vibrations in the opposite phase to the vibrations originating from the rotor 2 can be generated by the rotor blades 8, as indicated by the thick line in FIG. 13(B) , thereby reducing vibrations in the airframe. The rotor blades 8 are moved faster than the rotational speed of the rotor 2. The harmonic vibrations of the rotor blades 8 are controlled at an integer multiple of the frequency of the rotational speed of the rotor 2, and harmonic control is performed to shift the phase of the frequency of the rotor-origin vibrations.

[0157] In this way, by providing the rotor blades 8 that generate harmonic vibrations in the opposite phase to the vibrations originating from the rotor 2, it is possible to reduce the vibrations of the airframe. This reduces the load on the airframe, improving the durability and safety of the airframe, and also reducing the risk of failure or malfunction of various devices such as sensors mounted on the VTOL. It is also possible to reduce noise and improve passenger comfort.

[0158] Fifth Embodiment

[0159] FIG. 14A is a schematic side view of the vertical take-off and landing aircraft 1 of the first embodiment, and FIG. 14B is a schematic side view of a vertical take-off and landing aircraft 1D according to the fifth embodiment.

[0160] In the above embodiments, an example was given in which each rotor 2 is disposed above the rod-like support members 5 as shown in FIG. 14(A). However, each rotor 2 may also be disposed below the rod-like support members 5 as in a vertical take-off and landing aircraft 1D shown in FIG. 14(B). When the rotors 2 are disposed above the rod-like support members 5 as in the vertical take-off and landing aircraft 1 shown in FIG. 14(A), downdrafts are generated downward from the rotors 2 when lift is generated on the rotors 2 during take-off and landing (vertical ascent and descent) or hovering. This downdraft causes flow field interference with the rod-like support members 5, causing the rod-like support members 5 to generate a downward force on the aircraft that is opposite to the rotor lift. This is called downloading. This downloading requires the rotors 2 to generate even greater lift, which can deteriorate vertical take-off and landing performance and rotor performance during hovering.

[0161] To avoid the download, the rotor 2 may be positioned below the rod-like support member 5, as shown in Figure 14(B). With this configuration, the downdraft generated by the rotor 2 does not interfere with the flow field of the rod-like support member 5, and download can be avoided. This improves rotor performance. Note that during forward flight, rotor performance is not affected whether the rotor 2 is above or below the rod-like support member 5.

[0162] 14(A), it is preferable to provide the rotor 2 on the upper part of the rod-like support member 5. This makes it difficult for passengers aboard the vertical take-off and landing aircraft 1 to see the rotor 2 through the windows provided in the fuselage 3, which can eliminate psychological anxiety that may arise from seeing the rotor 2 and causing it to fly away, thereby providing the passengers with a visual sense of security. Furthermore, providing the rotor 2 on the upper part of the rod-like support member 5 makes it easier to avoid contact between the rotor 2 and people or objects outside the vertical take-off and landing aircraft 1 that has landed on the ground, thereby ensuring safety.

[0163] Sixth Embodiment

[0164] FIG. 15 is a schematic side view of a vertical take-off and landing aircraft 1E according to the sixth embodiment.

[0165] As in the vertical take-off and landing aircraft 1E shown in Figure 15, landing skids 19 may be attached to the lower part of the fuselage 3 to prevent the fuselage 3 from coming into direct contact with the ground E. The skids 19 may be, for example, a pair arranged side by side in the left-right direction and extending parallel in the fore-aft direction. The skids 19 may be of a type that can be retracted into the fuselage 3.

[0166] As shown in Figure 15, a vertical tail 7 extending downward is provided at the rear of the lower part of the rod-shaped support member 5. The tip 7a of the vertical tail 7 is preferably located below the plane of rotation of the propulsion propeller 6 in the vertical direction. More preferably, as shown in Figure 15, the inclination of an imaginary line L1 passing through the rearmost part 19a of the skid 19 and the lowest end of the plane of rotation of the propulsion propeller 6 with respect to the horizontal ground surface E is made larger than the inclination of an imaginary line L2 passing through the rearmost part 19a of the skid 19 and the rearmost part of the tip 7a of the vertical tail 7 with respect to the horizontal ground surface E.

[0167] This configuration prevents the propellers 6 from contacting the ground E when the aircraft lands, and also prevents the propellers 6 from being damaged and thrown into pieces due to contact, thereby improving aircraft safety. Furthermore, in the event of a hard landing on the ground E due to attitude instability during landing, the vertical stabilizer 7 touches down on the ground E before the propellers 6, preventing damage to the propellers 6. Furthermore, by attaching the vertical stabilizer 7 to the lower part of the rod-shaped support member 5 and arranging each rotor 2 above the rod-shaped support member 5, a decrease in attitude stability due to flow field interference from downwash caused by the rotors 2 is suppressed, and directional stability during forward flight is not significantly impaired.

[0168] Seventh Embodiment

[0169] During forward flight, as in the vertical take-off and landing aircraft 1F shown in FIG. 16 , the control unit 10 may control the plane of rotation of the forwardmost first rotors 21 (right first rotor 21R and left first rotor 21L) to be inclined forward with respect to the direction of travel, so that the first rotors 21 function as propulsion rotors in addition to or instead of the propulsion propellers 6. That is, during vertical take-off and landing (ascent / descent mode), the control unit 10 controls the first rotors 21 so that the plane of rotation assumes a horizontal attitude 31 (an attitude substantially perpendicular to the up-down direction). On the other hand, during forward flight (forward flight mode), the control unit 10 controls the plane of rotation so that it assumes a vertical attitude 32 that is substantially perpendicular to the direction of travel, for example, a vertical attitude 32 that is substantially perpendicular to the direction of travel.

[0170] Here, the rotor 2 mounted on the rod-shaped support member 5 generates a nose-up moment during forward flight, which may cause the aircraft to change its attitude in a nose-up direction, resulting in loss of aircraft stability. In contrast, as in the vertical take-off and landing aircraft 1F shown in Figure 16, the first rotor 21, which is positioned at the very front of the aircraft, ahead of the aircraft's center of gravity, can be tilted forward during forward flight to function as a propulsion propeller, thereby generating a nose-down moment around the center of gravity in addition to the thrust. This reduces the nose-up moment and improves the aircraft's stability.

[0171] Eighth Embodiment

[0172] As described above, the rotor 2 mounted on the rod-shaped support member 5 generates a head-up moment during forward flight, which may cause the aircraft to change its attitude in a head-up direction, resulting in loss of aircraft stability. In contrast, in the first to sixth embodiments, during forward flight, the control unit 10 may control the rotor rotation speed and / or blade pitch angle of the first rotor 21, which is located at the forefront of the aircraft and is forward of the center of gravity, without stopping the rotation, so as to minimize lift and air resistance. This reduces the head-up moment and improves aircraft stability. Furthermore, in this embodiment, since the first rotor 21 has four blades 25, completely stopping the rotation of the first rotor 21 would cause the blades 25 to protrude left and right relative to the rod-shaped support member 5, generating significant air resistance. However, by constantly rotating the first rotor 21, air resistance can be reduced.

[0173] Ninth Embodiment

[0174] In the above-described embodiments, examples have been given in which the number of blades of each rotor 2 is the same, but the number of blades of each rotor 2G may be different, as in the vertical take-off and landing aircraft 1G of this embodiment shown in Fig. 17. In this case, it is preferable that the value obtained by multiplying the number of blades by the area of ​​each blade is the same for each rotor 2G, and adjustments can easily be made to obtain the same lift for each rotor 2G.

[0175] Figure 17 is a schematic plan view of a vertical take-off and landing aircraft 1G of the ninth embodiment. Figure 18(A) is a conceptual diagram showing sound pressure fluctuations, with the solid line showing sound pressure fluctuations for a rotor with three blades, the dashed line showing sound pressure fluctuations for a rotor with four blades, and the dashed line showing sound pressure fluctuations for a rotor with five blades. Figure 18(B) is a conceptual diagram showing sound pressure fluctuations, with the solid line showing sound pressure fluctuations when the rotors have the same number of blades corresponding to the first embodiment, and the dashed line showing sound pressure fluctuations when the rotors have different numbers of blades according to this embodiment.

[0176] The vertical take-off and landing aircraft 1G has a first rotor group 210G consisting of two first rotors 21G (the right first rotor 21GR and the left first rotor 21GL) located at the forefront, a second rotor group 220G consisting of two second rotors 22G (the right second rotor 22GR and the left second rotor 22GL) located approximately in the center in the fore-and-aft direction, and a third rotor group 230G consisting of two third rotors 23G (the right third rotor 23GR and the left third rotor 23GL) located at the rearmost position, for a total of six rotors. When no distinction is made between the rotors, they will be referred to as rotors 2G. The arrangement and rotation direction of each rotor 2G are the same as those of the rotor 2 in the first embodiment.

[0177] The first rotor 21G has three blades 25. The second rotor 22G has four blades 25. The third rotor 23G has five blades 25.

[0178] As shown in Figure 18(A), because the number of blades is different, the period of the sound pressure fluctuations related to the number of blades changes for each rotor, and the frequency changes. As a result, in the ninth embodiment, in which the number of blades of each rotor is different, as shown in Figure 18(B), the sound pressure fluctuations that propagate far away are a composite of the sound pressure fluctuations generated by each rotor, and compared to the first embodiment in which the number of blades of each rotor is the same, the sound pressure level changes so that the sound pressure fluctuations are smaller, and noise can be reduced.

[0179] While various embodiments of the present invention have been described above, these embodiments are merely examples, and the present invention is not limited to the specific embodiments disclosed herein. It goes without saying that the scope of the present invention is not limited to these embodiments. For example, in the above-described embodiments, examples have been given in which the vertical take-off and landing aircraft has fixed wings, but the aircraft may not have fixed wings, and lift during forward flight may be generated solely by rotors.

[0180] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G... Vertical take-off and landing aircraft 2, 2G... Rotor for vertical lift, rotor 3... Fuselage 4... Fixed wing 5, 5A... Rod-shaped support member 6... Propulsion propeller 7... Vertical tail 7a... Tip of vertical tail 8... Rotating surface 10... Control unit 11... Rotor rotation direction 16... Memory device 21... First rotor, rotor, rotor located most forward 21R, 21GR... Right first rotor, rotor, rotor located most forward 21L, 21GL... Left first rotor, rotor, rotor located most forward 22... Second rotor, rotor 22R, 22GR... Right second rotor, rotor 22L, 22GL... Left second rotor, rotor 23... Third rotor 23R, 23GR... Right third rotor, rotor 23L, 23GL... Left third rotor, rotor 25... Blade 30: Plane of rotation 161: Data for calculating rotation speed (first data) 162: Data for calculating pitch angle (second data) 210, 210G: First rotor group 220, 220G: Second rotor group 230, 230G: Third rotor group

Claims

1. A vertical take-off and landing aircraft comprising: a pair of left and right rod-shaped support members extending in the fore-and-aft direction and provided on both the left and right sides; propulsion propellers; two or more rotors for vertical ascent and descent are arranged in the fore-and-aft direction on each of the rod-shaped support members, each having a plurality of blades and rotating in a predetermined rotational direction to generate lift; and a control unit that rotates the rotors during forward flight and controls the rotation speed of the rotors and the pitch angle of the blades so as to achieve a forward ratio, which represents the ratio between the flight speed and the wingtip speed of the rotors, that makes the effective lift-to-drag ratio of the rotors equal to or greater than a threshold value.

2. A vertical take-off and landing aircraft as described in claim 1, wherein the control unit: acquires flight speed information of the vertical take-off and landing aircraft; uses the flight speed information to calculate a range of the rotor rotation speed so that the forward advance rate will be such that the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value, based on first data prepared in advance that indicates the relationship between the effective lift-to-drag ratio of the rotor and the forward advance rate; uses the flight speed information to calculate a range of pitch angles of the blades that will generate the necessary lift for the rotor, within the calculated range of rotor rotation speeds; and determines the rotor rotation speed and the pitch angle of the blades within the calculated range of rotor rotation speeds and range of blade pitch angles.

3. A vertical take-off and landing aircraft as claimed in claim 2, wherein the control unit acquires attitude information of the vertical take-off and landing aircraft, and determines the rotation speed of the rotor and the pitch angle of the blades taking into account the attitude information.

4. A vertical take-off and landing aircraft as described in claim 2, further comprising a storage device for storing the first data prepared in advance and second data indicating the relationship between the rotor rotation speed, the pitch angle of the blades and the effective lift-to-drag ratio of the rotor for each flight speed, wherein the control unit uses the flight speed information in calculating the rotor rotation speed and calculates, based on the first data, a range of the rotor rotation speed at which the forward rate of the rotor's effective lift-to-drag ratio is equal to or greater than a threshold value, and uses the flight speed information in calculating the range of the blade pitch angle and calculates, based on the second data, a range of the blade pitch angle that will generate the necessary lift for the rotor, within the calculated range of rotor rotation speeds.

5. A vertical take-off and landing aircraft according to claim 1, wherein the forward advance ratio at which the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value is 0.5 or greater.

6. A vertical take-off and landing aircraft as claimed in claim 2, wherein the rotors are arranged on each of the rod-shaped support members in equal numbers to form a plurality of rotor groups each consisting of a pair of left and right rotors, and the control unit controls the rotation speed of a rotor belonging to one of the plurality of rotor groups so as to be different from the rotation speed of a rotor belonging to the other rotor groups, under the condition that the rotation speed of each of the rotors is within the range of the calculated rotor rotation speed.

7. A vertical take-off and landing aircraft as described in claim 1, wherein the control unit controls the rotation speed of the rotor and the pitch angle of the blades so that the forward rate is such that the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value during forward flight at a flight speed equal to or greater than a predetermined speed.

8. A vertical take-off and landing aircraft according to claim 7, wherein the predetermined speed is 100 km / h.

9. A vertical take-off and landing aircraft as described in claim 1, wherein the control unit rotates the two rotors, the centers of which are positioned adjacent to each other in the fore-aft direction on the same straight line parallel to the fore-aft direction, in forward flight in opposite directions.

10. A vertical take-off and landing aircraft as described in claim 9, wherein the rotors are arranged in three on each of the rod-shaped support members with their centers positioned on the same straight line parallel to the fore-and-aft direction, the three rotors arranged on the right-side rod-shaped support member are a right-side first rotor, a right-side second rotor and a right-side third rotor arranged in order from front to rear, and the three rotors arranged on the left-side rod-shaped support member are a left-side first rotor, a left-side second rotor and a left-side third rotor arranged in order from front to rear, and the control unit rotates the right-side first rotor, the right-side third rotor and the left-side second rotor so that their rotation direction is counterclockwise when viewed from above, and rotates the right-side second rotor, the left-side first rotor and the left-side third rotor so that their rotation direction is clockwise.

11. A vertical take-off and landing aircraft as described in claim 1, wherein of the two or more rotors arranged on each of the rod-shaped support members, two rotors positioned adjacent to each other in the fore-and-aft direction are arranged such that the center of one rotor is shifted laterally from the center of the other rotor.

12. A vertical take-off and landing aircraft as described in claim 11, wherein the rotors are arranged in three on each of the rod-shaped support members so that their vertical positions are the same; the three rotors arranged on the right rod-shaped support member are a right first rotor, a right second rotor and a right third rotor arranged in order from front to rear; the three rotors arranged on the left rod-shaped support member are a left first rotor, a left second rotor and a left third rotor arranged in order from front to rear; the right second rotor is positioned outward in the left-right direction from the right first rotor and the right third rotor, offset by the radius of the rotor's plane of rotation; and the left second rotor is positioned outward in the left-right direction from the left first rotor and the left third rotor, offset by the radius of the rotor's plane of rotation; The control unit rotates the right first rotor, the right second rotor, and the left third rotor so that their rotation direction is counterclockwise when viewed from above, and rotates the right third rotor, the left first rotor, and the left second rotor so that their rotation direction is clockwise. A vertical take-off and landing aircraft.

13. A vertical take-off and landing aircraft according to claim 1, wherein three or more of the rotors are arranged on each of the rod-like support members.

14. A vertical take-off and landing aircraft as described in claim 13, wherein the rotors are arranged on each of the rod-shaped support members in equal numbers to form a plurality of rotor groups, each consisting of a pair of left and right rotors, and a rotor belonging to one of the plurality of rotor groups is positioned in a different vertical direction from rotors belonging to the other rotor groups.

15. A vertical take-off and landing aircraft as claimed in claim 14, wherein the rotors are arranged in three on each of the rod-shaped support members so as to be positioned on the same straight line parallel to the fore-and-aft direction in a plan view, the three rotors arranged on the right rod-shaped support member are the right first rotor, the right second rotor and the right third rotor arranged in order from front to rear, the three rotors arranged on the left rod-shaped support member are the left first rotor, the left second rotor and the left third rotor arranged in order from front to rear, the right first rotor, the right second rotor, the left first rotor and the left second rotor are positioned at the same vertical position, and the right third rotor and the left third rotor are positioned higher than the right first rotor, the right second rotor, the left first rotor and the left second rotor, The control unit rotates the right first rotor, the right third rotor, and the left second rotor so that their rotation direction is counterclockwise when viewed from above, and rotates the right second rotor, the left first rotor, and the left third rotor so that their rotation direction is clockwise. A vertical take-off and landing aircraft.

16. A vertical take-off and landing aircraft as claimed in claim 14, wherein the rotors are arranged in three on each of the rod-shaped support members so as to be positioned on the same straight line parallel to the fore-and-aft direction in a plan view, the three rotors arranged on the right rod-shaped support member are the right first rotor, the right second rotor and the right third rotor arranged in order from front to rear, the three rotors arranged on the left rod-shaped support member are the left first rotor, the left second rotor and the left third rotor arranged in order from front to rear, the right first rotor, the right third rotor, the left first rotor and the left third rotor are positioned at the same vertical position, and the right second rotor and the left second rotor are positioned higher than the right first rotor, the right third rotor, the left first rotor and the left third rotor, The control unit rotates the right first rotor, the right second rotor, and the left third rotor so that their rotation direction is counterclockwise when viewed from above, and rotates the right third rotor, the left first rotor, and the left second rotor so that their rotation direction is clockwise. A vertical take-off and landing aircraft.

17. A vertical take-off and landing aircraft as claimed in claim 1, further comprising: a fuselage; and fixed wings connected to said fuselage and extending in the left-right direction linking said pair of left and right rod-shaped support members.

18. A vertical take-off and landing aircraft according to claim 17, further comprising a rotor blade arranged on the fixed wing, the rotor blade generating harmonic vibrations in the opposite phase to the vibrations originating from the rotor.

19. A vertical take-off and landing aircraft according to claim 1, wherein the rotor is disposed below the rod-shaped support member.

20. A vertical take-off and landing aircraft as described in claim 1, further comprising a vertical tail extending downward and disposed rearward of the lower part of said rod-shaped support member, the tip of said vertical tail being positioned below the plane of rotation of said propeller.

21. A vertical take-off and landing aircraft as described in claim 1, wherein the control unit controls the forward-most rotor during forward flight so that its plane of rotation is inclined forward with respect to the direction of travel, causing the rotor to function for propulsion in addition to or instead of the propulsion propeller.

22. A vertical take-off and landing aircraft as claimed in claim 1, wherein the control unit controls the rotation speed of the forward-most rotor and / or the pitch angle of the blades of the rotor so as to minimize the lift and air resistance of the forward-most rotor during forward flight.

23. A vertical take-off and landing aircraft as described in claim 1, wherein the rotors are arranged in equal numbers on each of the rod-shaped support members so as to form a plurality of rotor groups each consisting of a pair of left and right rotors, and the number of blades of a rotor belonging to one of the plurality of rotor groups is different from the number of rotors belonging to the other rotor groups.

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