Vertical takeoff and landing aircraft

Abstract

To provide a vertical takeoff and landing aircraft which can be miniaturized and accelerated.SOLUTION: A vertical takeoff and landing aircraft comprises a pair of left and right rod-like support members, a propulsion propeller, a rotor for vertically lifting, and a control part. The pair of left and right rod-like support members extend in a cross direction and are provided on both left and right sides. Two or more rotors are located on each rod-like support member in the cross direction, and each rotor has a plurality of blades and rotates in a prescribed rotation direction to generate a lift force. The control part rotates the rotors during forward flight, and controls the rotational speed of the rotors and the pitch angle of the blades so as to achieve a forward movement rate that represents the ratio between the flight speed and the blade tip speed of the rotors at which the effective lift-drag ratio of the rotors becomes a threshold or more.SELECTED DRAWING: Figure 9

Description

[Technical field]

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

[0002] A typical multi-rotor vertical take-off and landing aircraft is equipped with multiple rotors, and during forward flight the rotors are tilted forward to generate lift and thrust simultaneously. In addition, a combined (lift & cruise) multi-rotor vertical take-off and landing aircraft (see Patent Documents 1 to 5) equipped with rotors for vertical take-off and landing and thrust propellers and having fixed wings stops rotating the rotors during forward flight, generates thrust by the thrust propellers, and generates lift by the fixed wings.

[0003] In addition, Non-Patent Documents 1 and 2 describe a multi-rotor vertical take-off and landing aircraft equipped with four rotors and propellers, which generates lift by rotating the rotors during forward flight and propels the aircraft forward with 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 due to variable pitch and variable rotation speed using four rotors. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-151924 [Patent Document 2] JP 2022-148991 A [Patent Document 3] U.S. Patent Registration No. 10046853 [Patent Document 4] U.S. Patent Publication No. 2019-0127056 [Patent Document 5] China Patent Publication No. 115042968 [Non-patent literature]

[0005] [Non-Patent Document 1] 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" [Non-Patent Document 2] Proceedings of the 54th Fluid Mechanics Conference / 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 rear rotor vertical position on aerodynamic control of multirotors in forward flight" Summary of the Invention [Problem to be solved by the invention]

[0006] Multi-rotor vertical take-off and landing aircraft have a problem with high-speed performance because they need to generate lift and thrust simultaneously, while combined multi-rotor vertical take-off and landing aircraft have a problem with large aircraft size because they need to generate lift on the 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 compact and fast. [Means for solving the problem]

[0008] In order 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 ascent and descent, and a control unit. The pair of left and right rod-shaped support members extend in a front-to-rear direction and are provided on both the left and right sides. Two or more of the rotors are arranged on each of the rod-shaped support members in the front-to-rear direction, each of which has a plurality of blades and rotates 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 so as to achieve a forward ratio representing the ratio between the flight speed and the wingtip speed of the rotor at which the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value.

[0009] In a vertical take-off and landing aircraft according to one embodiment of the present invention, lift is generated by the rotor during forward flight, and thrust is generated by the propeller. By generating lift during forward flight by the rotor in this manner, part or all of the lift during forward flight can be secured by the rotor, and the aircraft can be made smaller. Furthermore, by providing a propeller, the aircraft can be made faster. Furthermore, by controlling the rotor speed during forward flight so that the forward rate (flight speed / wing tip speed) is such that the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value, the lift distribution can be adjusted so that the forward side of the rotor rotation plane generates a large lift, and the retreating side generates no lift or a state close to no lift. This makes it possible to adjust the wake distribution (downwash distribution) generated by the rotor, reducing flow field interference, which is interference of the forward rotor with the rear rotor caused by the downwash of the forward rotor, and suppressing deterioration of rotor performance due to flow field interference. By suppressing deterioration of rotor performance due to flow field interference, the rotor can more reliably secure part or all of the lift during forward flight, and the aircraft can be made smaller.

[0010] The control unit may acquire flight speed information of the vertical take-off and landing aircraft, use the flight speed information to calculate a range of the rotor's rotation speed based on first data prepared in advance indicating a relationship between the effective lift-to-drag ratio of the rotor and the forward forward rate so that the forward forward rate will be 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 rotor rotation speed 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 control unit may further include a storage device that stores the first data prepared in advance and second data indicating the relationship between the rotation speed of the rotor, the pitch angle of the blades, and the effective lift-to-drag ratio of the rotor for each flight speed, and in calculating the rotation speed of the rotor, the control unit may use the flight speed information and calculate, based on the first data, a range of rotation speeds of the rotor at which the forward rate at which the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value, and in calculating the range of the pitch angles of the blades, the control unit may use the flight speed information and calculate, based on the second data, 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.

[0013] The advance ratio 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 may be 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 to be different from the rotation speed of a rotor belonging to another rotor group, under conditions where 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 100km / h (approximately 28m / s).

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

[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 are arranged in three on each of the rod-shaped support members so that their positions in the up-down direction are the same, the three rotors arranged on the right 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 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, the right-side second rotor is positioned outward in the left-right direction from the right-side first rotor and the right-side third rotor by a radius of the rotation plane of the rotors, and the left-side second rotor is positioned outward in the left-right direction from the left-side first rotor and the left-side third rotor by a radius of the rotation plane of the rotors, and the control unit may rotate the right-side first rotor, the right-side second rotor and the left-side third rotor so that their rotation direction is counterclockwise when viewed from above, and rotate the right-side third rotor, the left-side first rotor and the left-side second rotor so that their rotation direction is clockwise.

[0021] Three or more of the 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 the other rotor groups.

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

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

[0026] The engine may further include a rotor blade disposed on the fixed blade and generating harmonic vibration in opposite phase to vibration 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 extending downwardly disposed rearward of a lower portion of the rod-shaped 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 plane of rotation is tilted forward with respect to the direction of travel, causing it to function for propulsion in addition to or in place of the propulsion propeller.

[0030] The control unit may control the rotation speed and / or the pitch angle of the blades of the forwardmost rotor so that lift and air resistance of the forwardmost 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 the number of blades of a rotor belonging to the other rotor groups. Effect of the Invention

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

[0033] Note that the effects described herein are not necessarily limited to those described herein, and may be any of the effects described in this disclosure. [Brief description of the drawings]

[0034] [Figure 1] 1 is a schematic perspective view of a vertical take-off and landing aircraft according to a first embodiment of the present invention. FIG. [Diagram 2] FIG. 1 is a schematic plan view of a vertical take-off and landing aircraft of a first embodiment. [Diagram 3] FIG. 1 is a schematic side view of a vertical take-off and landing aircraft of a first embodiment. [Figure 4] FIG. 2 is a block diagram showing the configuration of a control system for a rotor of a vertical take-off and landing aircraft according to each embodiment of the present invention. [Diagram 5] FIG. 4 is a diagram for explaining rotor control in a vertical take-off and landing aircraft according to each embodiment of the present invention. [Figure 6] FIG. 4 is a diagram for explaining rotor control in a vertical take-off and landing aircraft according to each embodiment of the present invention. [Figure 7] FIG. 4 is a control flow diagram of a control unit in the vertical take-off and landing aircraft of each embodiment of the present invention. [Figure 8] FIG. 1A is a conceptual diagram of the flow field interference of the front and rear rotors in a vertical take-off and landing aircraft that does not perform the rotation speed control of the present invention, and FIG. 1B is a conceptual diagram of the flow field interference of the front and rear rotors in a vertical take-off and landing aircraft of each embodiment that performs the rotation speed control of the present invention. [Figure 9] FIG. 4 is a schematic plan view of a vertical take-off and landing aircraft according to a second embodiment of the present invention. [Figure 10] FIG. 2A is a conceptual diagram of rotor flow field interference in a vertical take-off and landing aircraft of a first embodiment, and FIG. 2B is a conceptual diagram of rotor flow field interference in a vertical take-off and landing aircraft of a second embodiment. [Figure 11] 13(A) and 13(B) are schematic side views of a vertical take-off and landing aircraft according to a third embodiment of the present invention. [Figure 12] FIG. 11 is a cross-sectional view of a fixed wing for illustrating the movement of a moving surface of a vertical take-off and landing aircraft according to a fourth embodiment of the present invention. [Figure 13] 13(A) and 13(B) are graphs illustrating changes in vibration of the entire vertical take-off and landing aircraft caused by harmonic vibration of the rotor blades of the vertical take-off and landing aircraft according to the fourth embodiment. [Figure 14]FIG. 13(A) is a schematic side view showing the state of downdraft below the rotor that occurs during takeoff and landing in a vertical take-off and landing aircraft of the first embodiment, and FIG. 13(B) is a schematic side view showing the state of downdraft below the rotor that occurs during takeoff and landing in a vertical take-off and landing aircraft of the fifth embodiment of the present invention. [Figure 15] FIG. 13 is a schematic side view of a vertical take-off and landing aircraft according to a sixth embodiment of the present invention. [Figure 16] FIG. 13 is a schematic side view of a vertical take-off and landing aircraft according to a seventh embodiment of the present invention. [Figure 17] FIG. 13 is a schematic plan view of a vertical take-off and landing aircraft according to a ninth embodiment of the present invention. [Figure 18] 13A is a graph showing sound pressure fluctuations during rotor rotation due to differences in the number of rotor blades, and FIG. 13B is a graph showing sound pressure fluctuations during rotor rotation in each of the first and eighth embodiments. [Figure 19] 1A and 1B are conceptual diagrams for explaining a lift offset state of a rotor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same reference numerals are used to denote configurations that have already been described, and description thereof may be omitted.

[0036] First Embodiment

[0037] [Overall structure 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 control system for the rotor 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 ascent and descent (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 it moves horizontally (flying forward) is the forward direction, and the opposite direction is the backward direction. In addition, the direction to the right of the width direction of the vertical take-off and landing aircraft 1 when viewed from the vertical take-off and landing aircraft 1 facing forward is the right direction, and the direction to the left is the left direction. In addition, the vertical upward direction is the upward direction, and the vertical downward direction is the downward direction. The front-rear direction, the left-right direction, and the up-down direction are perpendicular to each other. In addition, 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. In addition, the "outer side in the left-right direction" means the side away from the vertical center line A (see FIG. 2) that divides the vertical take-off and landing aircraft 1 in half in the left-right direction (width direction) when viewed in a plan, and the "inner side in the left-right direction" means the side approaching the vertical center line A when viewed in a plan. In addition, the "rotation direction" of the rotor 2 refers to the rotation direction when viewed in a plan.

[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 long shape in the front-to-rear direction 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 extending in the left-right direction, and connect a pair of left and right rod-shaped support members 5R and 5L described later. The two fixed wings 4 are located at the front and rear 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 are referred to as fixed wings 4. The fixed wings 4 generate part 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 viewpoint of the stability of the aircraft, it is preferable to change the mounting angles of the front fixed wing 41 and the rear fixed wing 42. For example, the mounting angle of the rear fixed wing 42 may be set to be about 1 degree larger than the mounting angle of the front fixed wing 41. This allows the lift generated by the fixed wing 4 to be larger at the rear of the aircraft than at the front, generating a head-down moment of the aircraft, which contributes to improving the static stability of the aircraft. In addition, if the mounting angles of the front fixed wing 41 and the rear fixed wing 42 are the same, the lift generated by the rear fixed wing 42 is reduced due to the downwash generated by the front fixed wing 41, but by making the mounting angle of the rear fixed wing 42 larger than that of the front fixed wing 41, the lift generated by the rear fixed wing 42 can be corrected and secured.

[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. The rod-shaped support member located on the right side of the pair of left and right rod-shaped support members 5 is given the symbol 5R, and the rod-shaped support member located on the left side is given the symbol 5L, but they are referred to as rod-shaped support members 5 when there is no need to particularly distinguish them. In this specification, the rod-shaped support member 5 "extending in the front-rear direction" is not limited to a mode in which the rod-shaped support member 5 extends parallel to the front-rear direction, but 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 later. In this embodiment, the rod-shaped support member 5 has 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 form in which two or more rotors are arranged on the same straight line parallel to the front-rear direction, as well as a form 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 as a whole.

[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 vertical 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 rotors 2 are arranged in equal numbers on the upper parts of the rod-shaped support members 5. The three rotors 2 arranged on the right rod-shaped support member 5R are called the right first rotor 21R, the right second rotor 22R, and the right third rotor 23R, in order from front to rear. The three rotors 2 arranged on the left rod-shaped support member 5L are called the left first rotor 21L, the left second rotor 22L, and the left third rotor 23L, in order from front to rear. When there is no need to distinguish between them, they are called rotors 2. The right first rotor 21R and the left first rotor 21L, the right second rotor 22R and the left second rotor 22L, and the right third rotor 23R and the left third rotor 23L are located at the same position in the front-to-rear 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 rotors 2 on the left and right. 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 are referred to as the first rotor 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 the 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 later, the rotor 2, together with the fixed wing 4, is responsible for generating lift during forward flight. Furthermore, the rotation speed of the rotor 2 and the pitch angle of the blades 25 are individually controlled for each rotor 2. The rotation direction of the rotor 2 is set according to the rotor's arrangement position.

[0056] In this embodiment and each of the embodiments described later, the rotor is used to generate lift during forward flight, so that the entire aircraft lift does not need to depend on the fixed wing, and the span length (width) of the fixed wing can be reduced, and the overall width size of the vertical take-off and landing aircraft can be reduced. In addition, although details will be described later, in this embodiment and each of the embodiments described later, the relationship between the forward rate (flight speed / wing tip speed) and the effective lift-to-drag ratio of the rotor is used to control the rotor rotation speed and the pitch angle of the blades, thereby suppressing the deterioration of rotor performance due to flow field interference and improving rotor performance. By improving the rotor performance, the proportion of lift generated by the fixed wing in the entire aircraft lift can be reduced, making it possible to reduce the size of the fixed wing and thus the size of the vertical take-off and landing aircraft. Note that in this embodiment and each of the embodiments described later, a vertical take-off and landing aircraft with a fixed wing is taken as an example, but the present invention can also be applied to a vertical take-off and landing aircraft without a fixed wing. By generating lift during forward flight only with the rotor, the fixed wing can be omitted, and the vertical take-off and landing aircraft can be made smaller.

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

[0058] In contrast, in the vertical take-off and landing aircraft according to this embodiment and each of the embodiments described below, the rotor is rotated in a predetermined direction during forward flight, and the rotor speed and the pitch angle of the blades 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 value. This makes it possible to generate the lift required for the rotor 2 while minimizing the deterioration 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 the blade 25 is attached to the hub. The other longitudinal end of the 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 blade 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 with reference to 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 when the vertical take-off and landing aircraft 1 is viewed from in front of the vertical take-off and landing aircraft 1 in forward flight, along line BB in Figure 19(A). 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 on the right half of the rotation surface 30 is the area where the blades 25 rotate in a forward direction (towards the front of the aircraft), and is called the "forward side." The plain area on the left half of the rotation surface 30 is the area where the blades 25 rotate in a backward direction (towards the rear of the aircraft), 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] In forward flight, the rotors 2 mounted on the vertical take-off and landing aircraft 1 have different relative speeds 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, so the relative speed on the blades is faster. On the retreating side, the horizontal flight speed (V) and the rotational speed (rΩ) cancel each other out, so the relative speed is slower. As a result, as shown in FIG. 19(B), in general, the rotor 2 generates a larger lift on the forward side than on the retreating side, so that a gap occurs in the lift distribution when viewed over the entire rotation plane 30, and the point of action of the lift is shifted from the center (lift offset state). In this specification, the "horizontal flight speed" may be simply referred to as the "flight speed".

[0064] (propeller)

[0065] As shown in Figs. 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 the 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 front-rear 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 front-rear direction.

[0066] As shown in FIG. 1 and FIG. 4, each propulsion propeller 6 has a motor 68, a hub (not shown) connected to the output shaft of the motor 68, and a plurality of 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) for supplying power to the motor 68 are provided in the fuselage 3. The mounting position of the battery is not necessarily limited to inside the fuselage. For example, in view of the weight of the power wiring, the battery may be arranged as close to the individual motors as possible. The battery may also be arranged in a distributed manner inside or under the support member. In this embodiment, each propulsion propeller 6 has four blades 65. The rotation plane of each propulsion propeller 6 is vertical. The propulsion propeller 6 generates a forward propulsive force by the rotation of the blades 65, and the vertical take-off and landing aircraft 1 is capable of moving 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 propulsion propellers 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 tail 7 is disposed connected to the lower rear of each of the pair of left and right rod-shaped support members 5R and 5L. The vertical tail 7 connected to the right rod-shaped support member 5R and extending downward is referred to as the right vertical tail 7R, and the vertical tail 7 connected to the left rod-shaped support member 5L and extending downward is referred to as the left vertical tail 7L, and when there is no need to particularly distinguish between the two, they are referred to as the vertical tail 7. The vertical tail 7 is responsible for maintaining the lateral stability of the vertical take-off and landing aircraft 1. The vertical tail may be provided extending upward from the upper part of the rod-shaped support member 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 memory device 16, and sensors 17.

[0072] (Sensors)

[0073] The sensors 17 are composed of various sensors that detect the flight state of the vertical take-off and landing 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 by 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 any one of an ascent mode, a forward flight mode, and a hovering mode. The ascent 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 in this embodiment, an example of ascending or descending vertically is given, but it may also ascend or descend obliquely like a fixed-wing aircraft.

[0076] The aircraft ascends vertically (or ascends obliquely) in ascent / descent mode, and when it reaches a certain altitude, the propulsion propeller 6 is activated and transitions to forward flight mode. In forward flight mode, the aircraft flies in a constant rotation speed mode in which the rotor rotation speed is constant until it reaches a predetermined flight speed (100 km / h (approximately 28 m / s) in this embodiment), and when it reaches or exceeds the predetermined flight speed (100 km / h in this embodiment), it transitions to a variable rotation speed mode, and the rotor rotation speed and blade pitch angle control according to the present invention are performed. In the landing posture, the aircraft reduces its flight speed in forward flight mode, and when the flight speed falls below the predetermined flight speed, it changes from the variable rotation speed mode to the constant rotation speed mode, and further gradually reduces its flight speed. Thereafter, it transitions to ascent / descent mode, descends vertically, and lands. The rotor rotation speed in the variable rotation speed mode of the forward flight mode is controlled to be smaller than the rotor rotation speed in the ascent / descent mode and the constant rotation speed mode of the forward flight mode.

[0077] The control unit 10 individually controls each rotor 2 and each propulsion propeller 6 according to each mode. The control unit 10 controls the rotation speed, etc. of the propulsion propellers 6, and controls the flight speed, etc. 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 rotational 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 / tip speed) is such that the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value.

[0079] In detail, the control unit 10 uses the flight speed information to calculate the range of rotor rotation speeds based on first data prepared in advance indicating the relationship between the effective lift-drag ratio of the rotor and the forward advance rate (flight speed / wing tip speed) so that the forward advance rate is equal to or greater than a threshold value. Then, the control unit 10 uses the flight speed information to calculate the range of blade pitch angles that generate the necessary lift for the rotor within the calculated range of rotor rotation speeds. Next, the control unit 10 determines the rotation speeds of the rotors and the pitch angles of the blades within the calculated range of rotor rotation speeds and the range of 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 the forward flight mode, the control unit 10 controls the rotation direction of each rotor according to the arrangement position of the rotor 2. The rotation direction of a rotor is determined according to the downwash distribution of the rotor in front of it so as to reduce flow field interference.

[0084] (Storage device)

[0085] 5 and 6 are 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. 6(A) and (B) 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 when calculating the range of the rotor rotation speed to minimize the deterioration of the aerodynamic performance due to the flow field interference. The rotation speed calculation data 161 indicates the relationship between the forward 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 ratio, whereby when a vertical take-off and landing aircraft 1 equipped with multiple rotors 2 for vertical ascent and descent and propulsion propellers 6 is flying forward at a flight speed of 100 km / h or more, the effective lift-drag ratio of the rotor becomes stable above a threshold value when the forward forward ratio (flight speed / rotor tip speed) reaches a predetermined value (0.5) or more, as shown in the rotation speed calculation data 161 in FIG. 5.

[0089] By controlling the rotor speed based on the data 161 for calculating the rotation speed using the flight speed information, it is possible to adjust the distribution of lift (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 speed that provides a forward rate (0.5 or more) that makes the effective lift-to-drag ratio of the rotor equal to or greater than a threshold value, 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 the forward side of the rotation plane 30 of the rotor 2 generates a large lift and the retreating side generates no lift or a state close to that. By controlling the rotation direction of the rotor in consideration of the downwash distribution and the rotor position, it is possible to suppress the deterioration of rotor performance due to flow field interference and minimize the 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 wing tip speed RΩ (R is the rotor radius and Ω is the rotational speed). The wing tip speed is the speed of the wing tip 27 corresponding to the tip of the blade 25.

[0091] 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 rotor 2 is an index of rotor performance. The higher the effective lift-to-drag ratio, the smaller the air resistance, and the higher the energy efficiency and rotor performance. Effective drag D E is defined as follows:

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

[0093] As shown in the data 161 for calculating the rotational speed in FIG. 5, when the forward advance ratio (flight speed / rotor tip speed) is in the range of 0.2 or more, the effective lift-drag ratio tends to become higher as the forward advance ratio value increases. Furthermore, when the forward advance ratio is 0.5 or more, the effective lift-drag ratio of the rotor stabilizes to be in the range of approximately 6.0 to 6.5. In other words, by controlling the rotor 2 at a rotor rotational speed that provides a forward advance ratio (0.5 or more) that provides the effective lift-drag ratio of the rotor to a threshold value or more (the threshold value is 6.0 in the example shown in FIG. 5), the change in rotor performance is reduced, and the rotor performance is stabilized in a good state. A larger forward advance ratio for a certain flight speed means a smaller rotor rotational speed, and by reducing the rotational speed, the effective lift-drag ratio of the rotor can be increased.

[0094] Here, the "threshold" of "the effective lift-drag ratio of the rotor is equal to or greater than the threshold" is the value when the effective lift-drag ratio of the rotor starts to become stable, and in the example shown in FIG. 5, the threshold is 6.0. The threshold can be changed depending on the arrangement position of the rotor 2. For example, when the rotors are arranged on the same straight line as in this embodiment, the threshold of the effective lift-drag ratio of the rotor is lower for the first rotor 21 and the second rotor 22 than for the third rotor 23, but the shape of the graph (see FIG. 5) showing the correlation between the forward advance rate and the effective lift-drag ratio of the rotor is similar, and the manner of change is the same. In any rotor, the effective lift-drag ratio of the rotor becomes equal to or greater than the threshold, that is, the rotor performance becomes stable when the forward advance rate is 0.5 or greater. The reason why the threshold of the effective lift-drag ratio of the third rotor 23 is lower is because the third rotor 23 is affected by the downdraft 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 to calculate the range of pitch angles of the blades 25 that will generate the lift required for the rotor 2, within the range of the rotor rotation speed calculated using the rotation speed calculation data 161. Then, within the calculated range of the rotor rotation speed and pitch angle, 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.

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

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

[0101] 2 and 10(A), how the rotation direction of the rotor 2 is controlled will be described below. 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 higher than a predetermined speed (100 km / h) will be described using Figures 5, 6, and 8 along with the control flow in Figure 7.

[0102] Fig. 10(A) is a right 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. Fig. 7 is a control flow diagram by the control unit 10. Figs. 8(A) and (B) are conceptual diagrams for explaining the flow field interference of two rotors located adjacent to each other in the front-rear direction on the same straight line parallel to the front-rear direction, and show the lift distribution and downwash distribution generated on the rotor rotation plane. In the explanation using Figs. 8(A) and (B), the rotor located at the front of the two rotors 2 (hereinafter referred to as the front rotor) is given the symbol 2F, and the rotor located at the rear (hereinafter referred to as the rear rotor) is given the symbol 2R.

[0103] Fig. 8(A) is a conceptual diagram of flow field interference in a multi-rotor aircraft without a propeller 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 it is necessary for the rotors to generate lift and thrust simultaneously, and the forward advance ratio is, for example, about 0.2 to 0.4. Fig. 8(A) shows a conceptual diagram of flow field interference when, for example, the forward advance ratio is about 0.3 and the rotor effective lift-drag ratio is about 4.

[0104] 8(B) is a conceptual diagram of flow field interference when controlling the rotor speed according to the present invention, where the forward advance 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 embodiment described below are equipped with a propeller 6, and the propeller 6 provides thrust during forward flight, with the rotors 2 contributing only to the generation of lift. For this reason, during forward flight at a flight speed equal to or greater than a predetermined speed, the rotor 2 speed can be changed to a lower speed, and the forward advance rate can be increased.

[0105] (Rotation direction control)

[0106] 10(A), when the centers of two rotors 2 adjacent in the fore-aft direction are located on the same straight line parallel to the fore-aft 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 fore-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.

[0107] 2 and 10(A), 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] Incidentally, control of the rotation direction in a case where the centers of two rotors 2 adjacent in the front-rear direction are positioned offset in the left-right direction will be described in a second embodiment.

[0110] (Determination of 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 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 flight speed information to calculate a range of rotor speeds for the rotor 2, based on the rotation speed calculation data 161, so 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 forward moving side and no lift or nearly so is generated on the retreating side, as shown in Fig. 8(B). Therefore, the downwash distribution 12 can also be adjusted so that large downwash is generated behind the forward moving side of the front rotor 2F and no downwash is generated or nearly so is generated behind the retreating side of the front rotor 2F.

[0113] By adjusting the lift distribution and downwash distribution on the rotor rotation surface in this way and controlling the rotor rotation direction as described above, the forward side of the rotation surface 30 of the rear rotor (e.g., second right rotor 22R) is located behind the backward side of the rotation surface 30 of the front rotor (e.g., first right rotor 21R) in two rotors adjacent in the fore-and-aft direction. As a result, the forward side of the rotation surface of the rear rotor, where lift is mainly generated, is less susceptible to the downwash caused by the front rotor, and flow field interference can be reduced.

[0114] 10(A), the third rotor 23 is affected by the downflow of the first rotor 21 and the second rotor 22 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 less affected by the downflow of the second rotor 22, although it is affected by the downflow of the first rotor 21 which rotates in the same direction, and flow field interference can be reduced.

[0115] In this way, in forward flight mode, the rotor 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. This eliminates the need to increase the rotor rotational power of the rear rotor 2R to generate the necessary lift due to the effect of downwash, thereby suppressing the deterioration of rotor performance of the rear rotor 2R due to flow field interference, and minimizing the deterioration of aerodynamic performance.

[0116] 8(A), in a comparative example in which the rotor speed control of this embodiment is not performed, for example, when the forward advance ratio is 0.3, the forward advance side of the front rotor 2F also tends to generate a large lift, and in downwash distribution 12, a large downwash occurs behind the forward advance side of the front rotor 2F, and this downwash significantly affects the forward advance side of the rear rotor 2R. Therefore, in order to generate the lift required for the rear rotor 2R, it becomes necessary to increase the rotor rotation 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 the lift required for each rotor 2 to keep the aircraft in a horizontal attitude based on the attitude information, and calculates the range of pitch angles of the blades 25 to obtain the required lift (ST3). In detail, the control unit 10 uses the flight speed information to calculate the range of blade pitch angles 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 Fig. 6(A).

[0119] Next, the control unit 10 determines, for each rotor 2, a blade pitch angle that will increase the effective lift-drag ratio of the rotor within the calculated blade pitch angle range based on the data shown in Fig. 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 is adjusted to generate the required lift by adjusting the blade pitch angle, and to reduce the air resistance of the rotor 2 at a low rotation speed.

[0120] Here, when determining the rotor rotation speed and the blade pitch angle, if the rotation speeds of the rotors 2 are set to be the same, noise may occur due to vibrations originating from the rotors 2. For this reason, from the viewpoint of reducing noise, 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] The control of the rotor rotation speed and the blade pitch angle using the rotation speed calculation data 161 and the pitch angle calculation data 162 is preferably used when the flight speed is 100 km / h or more. When the flight speed is less than 100 km / h, it is difficult to generate sufficient lift with the rotor if the above control is performed.

[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 degradation due to flow field interference is suppressed and rotor performance is improved, making it possible to reduce the size and increase the speed.

[0123] Furthermore, the aircraft may also be a vertical take-off and landing aircraft that does not have fixed wings 4. By controlling the rotor 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 the aircraft smaller.

[0124] The vertical take-off and landing aircraft of this embodiment and each embodiment described later has six rotors 2. This improves redundancy and improves safety. Even if one rotor 2 fails, the remaining rotors 2 can continue to provide lift. When 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 of the embodiments described below have six rotors 2, but four or more rotors are sufficient, and the present invention can be applied to any number of rotor groups consisting of two rotors in pairs arranged in the fore-and-aft direction.

[0126] Other embodiments will be described below, focusing on the differences from the first embodiment. Similar configurations are given similar reference numerals and descriptions may be omitted. In each of the following embodiments, as in the first embodiment, the rotor speed and blade pitch angle are controlled using the relationship between the forward forward rate and the effective lift-to-drag ratio of the rotor 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 in a straight line parallel to the fore-aft direction, but 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-aft direction, as in a vertical take-off and landing aircraft 1A shown in Fig. 9. 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-aft direction convex outward in the left-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, not on a straight line parallel to the front-rear direction, but offset in the left-right direction along a curve. As shown in FIG. 9, in a plan view, the right second rotor 22R is offset by the radius of the rotation plane 30 outward from the right first rotor 21R and the right third rotor 23R in the left-right direction. The right first rotor 21R and the right third rotor 23R are positioned at the same distance from the vertical center line A in the left-right direction. Similarly, the left second rotor 22L is offset by the radius of the rotation plane 30 outward from the left first rotor 21L and the left third rotor 23L in the left-right direction. The left first rotor 21L and the left third rotor 23L are positioned at the same distance from the vertical center line A in the left-right direction. In this embodiment, similarly to 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 the centers of two rotors 2 that are adjacent in the front-rear direction and have the same vertical height are shifted in the left-right direction by the radius of the rotor rotation surface 30 as in this embodiment, the rotation direction of the rotors 2 is controlled to be in the following forms (1) and (2). In this embodiment, the two rotors 2 adjacent in the front-rear 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 front-rear 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 outboard in the left-right direction by the radius of the rotation plane 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 rotation plane 30 of the rear rotor, and the backward side of the rotation plane 30 of the rear rotor is positioned behind the forward side of the rotation plane 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 rotation plane 30 where lift is mainly generated.

[0133] (2) When the rear rotor is positioned laterally inward by the radius of the rotation plane of the front rotor, the rotation directions of the front and rear rotors are controlled to be reversed so that the front rotor is not positioned immediately in front of the forward side of the rotation plane 30 of the rear rotor, and the retreating side of the rotation plane 30 of the rear rotor is positioned behind the retreating side of the rotation plane 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 rotation plane 30 where lift is mainly generated.

[0134] In this embodiment, as shown in Fig. 9, the first right rotor 21R and the second right rotor 22R rotate in a counterclockwise direction, and the third right rotor 23R rotates in a clockwise direction. The first left rotor 21L and the second left rotor 22L are controlled to rotate in a clockwise direction, and the third left rotor 23L rotates in a counterclockwise direction. By controlling the rotation direction in this manner, each rotor is positioned such 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 according to the rotor arrangement positions in this way, the second rotor 22 (rear rotor) is less susceptible to the downdraft caused by 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 (2). By controlling the rotational direction of the rotors according to the rotor arrangement positions in this way, the third rotor 23 (rear rotor) is less susceptible to the downdraft caused by 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 FIG. 9 and FIG. 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 front-rear direction. In such an arrangement, the right third rotor 23R is affected by the downdraft of the right first rotor 21R, but in this embodiment, the rotation direction is controlled so that the retreating side, where the right first rotor 21R generates no lift or is in a state close to that, is located in front of the forward moving side of the right third rotor 23R, so that 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 is true for the left side.

[0138] As described above, in this embodiment, some of the rotors are positioned further outboard in the left-right direction than the other rotors, so that the width size of the aircraft is larger than in the first embodiment. However, 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 with reference to Fig. 11. Fig. 11(A) is a schematic side view of vertical take-off and landing aircraft 1B, and Fig. 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 linearly parallel to the front-rear 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 front-rear direction in a plan view.

[0141] In the first embodiment, an example was given in which the six rotors 2 are positioned at the same vertical position, but as shown in Figures 11(A) and (B), the positions in the vertical direction may be different. By changing the height of the rear rotor of two rotors adjacent in the fore-aft 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 restricted, and the range of design is widened. The rear rotor is arranged so that it is positioned higher than the front rotor by about 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 FIG. 11(A), the first rotor 21 and the second rotor 22 are at the same position in the vertical direction. The third rotor 23 is located 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 for changing the rotor height to the rod-shaped support member 5. When adding the structure 29, it is preferable to make the structure 29 streamlined in order to avoid an increase in air resistance. As in the first embodiment, it is preferable to determine the rotation direction of each rotor 2 in consideration of the downwash distribution based on the conceptual diagram of flow field interference between the front and rear rotors as shown in FIG. 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-rear direction in a plan view, and as shown in Fig. 11(A), the third rotor 23 is positioned above 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-rear direction and are at the same vertical position, similar to 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 in this way and controlling the rotation direction according to the rotor arrangement position, it is possible to reduce flow field interference.

[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 structure 29 for changing the rotor height 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), in each rod-shaped support member 5, the rotation direction of the second rotor 22 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 located higher than the first rotor 21, the second rotor 22 is less susceptible to the effect of downflow 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 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 second rotor 22R. Since 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 downdraft caused by the right second rotor 22R is distributed in a state in which no downdraft is generated or a state close to it behind the retreating side of the rotation plane 30 of the right second rotor 22R, and the right third rotor 23R is less susceptible to the downdraft of the right second rotor 22R. The same is true on the left side.

[0152] Moreover, 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 front-rear direction on the same straight line parallel to the front-rear direction, are at the same vertical position and rotate in opposite directions. In other words, the forward 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. Since the rotors are controlled to have a lift distribution in which no lift is generated or a state close to it on the retreating side, the downdraft caused by the right first rotor 21R has a downdraft distribution in which no downdraft is generated or a state close to it behind the retreating side of the rotation plane 30 of the right first rotor 21R, and the right third rotor 23R is 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 the right second rotor 22R located in front of it. The same is true on the left side.

[0153] As described above, in the vertical take-off and landing aircraft 1C, all of the rotors are configured to avoid flow field interference. By varying the vertical positions of the rotors in this way and controlling the rotation direction according to the rotor arrangement position, it is possible to reduce flow field interference.

[0154] <Fourth embodiment>

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

[0156] The vibration originating from the rotor 2 occurs due to a lift distribution in which the lift is larger on the forward side in the rotation plane 30 of the rotor 2, and causes vibration of the airframe. As shown in FIG. 12, in this embodiment and each of the other embodiments, the rotor blade 8 may be configured to move in the vertical direction so as to generate harmonic vibration in the opposite phase to the vibration originating from the rotor 2. As shown in FIG. 13(A), the vibration of the airframe can be reduced as shown by the thick line in FIG. 13(B) by generating vibration in the opposite phase to the vibration originating from the rotor 2 by the rotor blade 8. The rotor blade 8 is moved faster than the rotation speed of the rotor 2. The harmonic vibration of the rotor blade 8 is controlled at an integer multiple of the frequency of the rotation speed of the rotor 2, and harmonic control is performed so as to shift the phase of the frequency of the vibration originating from the rotor.

[0157] In this way, by providing the rotor blades 8 which generate harmonic vibrations in the opposite phase to the vibrations originating from the rotor 2, the vibrations of the aircraft can be reduced. This reduces the load on the aircraft, improves the durability and safety of the aircraft, and also reduces the risk of failure or malfunction of various devices such as sensors mounted on the vertical take-off and landing aircraft. It also reduces noise and improves 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-mentioned embodiments, an example in which each rotor 2 is disposed above the rod-shaped support member 5 as in FIG. 14(A) has been given, but each rotor 2 may be disposed below the rod-shaped support member 5 as in a vertical take-off and landing aircraft 1D shown in FIG. 14(B). When the rotor 2 is disposed above the rod-shaped support member 5 as in the vertical take-off and landing aircraft 1 shown in FIG. 14(A), when lift is generated in the rotor 2 during take-off and landing (vertical ascent and vertical descent) or during hovering, downdraft occurs downward from the rotor 2. This downdraft causes flow field interference with the rod-shaped support member 5, and the rod-shaped support member 5 generates a downward force on the aircraft that is opposite to the rotor lift. This is called downloading. This downloading requires the rotor 2 to generate even greater lift, and downloading causes deterioration of vertical take-off and landing performance and rotor performance during hovering.

[0161] In order to avoid the above download, the rotor 2 may be disposed below the rod-shaped support member 5 as shown in FIG. 14(B). With this configuration, the downflow generated by the rotor 2 does not interfere with the flow field of the rod-shaped support member 5, and download can be avoided. This improves rotor performance. During forward flight, rotor performance is not affected whether the rotor 2 is above or below the rod-shaped support member 5.

[0162] In the case of a manned aircraft, it is preferable to provide the rotor 2 on the upper part of the rod-shaped support member 5 as shown in Fig. 14(A). 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, and this can eliminate the psychological anxiety that may be caused by seeing the rotor 2 and the rotor 2 flying off into the air, thereby providing the passengers with a visual sense of security. Furthermore, providing the rotor 2 on the upper part of the rod-shaped 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 in Fig. 15, landing skids 19 may be attached to the lower part of the fuselage 3 so as to prevent the fuselage 3 from directly contacting the ground E. The skids 19 are, for example, arranged in a pair 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 Fig. 15, a vertical tail 7 extending downward is provided behind the lower part of the rod-shaped support member 5. It is preferable that the tip 7a of the vertical tail 7 is located below the plane of rotation of the propulsion propeller 6 in the up-down direction. More preferably, as shown in Fig. 15, the inclination of an imaginary straight 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 straight 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] With this configuration, it is possible to prevent the propulsion propellers 6 from contacting the ground E when the aircraft lands, and at the same time, to prevent the propulsion propellers 6 from being damaged and scattered 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 tail 7 touches the ground E before the propulsion propellers 6, so damage to the propulsion propellers 6 can be prevented. Furthermore, by attaching the vertical tail 7 to the lower part of the rod-shaped support member 5 and arranging each rotor 2 at the upper part of the rod-shaped support member 5, it is possible to suppress a decrease in attitude stability due to flow field interference of the downwash caused by the rotors 2, and to prevent a significant loss of directional stability during forward flight.

[0168] Seventh embodiment

[0169] During forward flight, as in a 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 rotor 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 rotor 21 functions as a propulsion rotor in addition to or in place of the propulsion propeller 6. That is, during vertical take-off and landing (ascent mode), the control unit 10 controls the first rotor 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 to be inclined forward with respect to the direction of travel, for example, to assume a vertical attitude 32 substantially perpendicular to the direction of travel.

[0170] Here, 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 the head-up direction, resulting in loss of aircraft stability. In response to this, as in the case of a vertical take-off and landing aircraft 1F shown in Fig. 16, the first rotor 21, which is located at the very front of the aircraft, forward of the aircraft's center of gravity, can be tilted forward during forward flight to function as a propulsion propeller, thereby generating a head-down moment around the center of gravity at the same time as the propulsive force. This reduces the head-up moment and improves the stability of the aircraft.

[0171] Eighth embodiment

[0172] As described above, the rotor 2 provided 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, thereby impairing the aircraft stability. In response to this, in the first to sixth embodiments, the control unit 10 may control the rotor rotation speed and / or the blade pitch angle of the first rotor 21, which is disposed at the frontmost part of the aircraft, forward of the center of gravity, during forward flight, without stopping the rotation, so that lift and air resistance are minimized. This can reduce the head-up moment and improve the stability of the aircraft. In addition, in this embodiment, since the first rotor 21 has four blades 25, if the rotation of the first rotor 21 is completely stopped, the blades 25 will protrude in the left and right directions relative to the rod-shaped support member 5, causing large air resistance, but by constantly rotating the first rotor 21, the air resistance can be adjusted to be small.

[0173] <Ninth embodiment>

[0174] In each of the above-described embodiments, the rotors 2 have the same number of blades, but the rotors 2G may have different numbers of blades, as in a 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 equal for each rotor 2G, and it is easy to adjust each rotor 2G to obtain the same lift.

[0175] Fig. 17 is a schematic plan view of a vertical take-off and landing aircraft 1G of the ninth embodiment. Fig. 18(A) is a conceptual diagram showing sound pressure fluctuations, where the solid line shows the sound pressure fluctuations of a rotor with three blades, the dashed line shows the sound pressure fluctuations of a rotor with four blades, and the dashed line shows the sound pressure fluctuations of a rotor with five blades. Fig. 18(B) is a conceptual diagram showing sound pressure fluctuations, where the solid line shows the sound pressure fluctuations when the rotors have the same number of blades corresponding to the first embodiment, and the dashed line shows the 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 (right first rotor 21GR and left first rotor 21GL) located at the forefront, a second rotor group 220G consisting of two second rotors 22G (right second rotor 22GR and 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 (right third rotor 23GR and left third rotor 23GL) located at the rearmost position, for a total of six rotors. When no distinction is made between the rotors, they are 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 Fig. 18(A), by having different numbers of blades, the period of sound pressure fluctuation 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 Fig. 18(B), the sound pressure fluctuation transmitted to a distant location is a combination 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 fluctuation is smaller, and noise can be reduced.

[0179] Various embodiments of the present invention have been described above, but 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 each of the above-mentioned embodiments, an example was given in which the vertical take-off and landing aircraft has fixed wings, but the aircraft does not need to have fixed wings, and lift during forward flight may be generated only by the rotors. [Explanation of symbols]

[0180] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G...Vertical takeoff and landing aircraft 2, 2G: Rotor for vertical lifting, rotor 3. Torso 4…Fixed wing 5, 5A…Rod-shaped support member 6...Propulsion propeller 7...Vertical stabilizer 7a…Tip of vertical stabilizer 8... Moving blade 10...Control section 11...Rotor rotation direction 16…Storage device 21...First rotor, rotor, rotor located at the front 21R, 21GR: right first rotor, rotor, rotor located furthest forward 21L, 21GL: Left first rotor, rotor, rotor located furthest forward 22...Second rotor, rotor 22R, 22GR: Right 2nd rotor, rotor 22L, 22GL: Left second rotor, rotor 23…Third rotor 23R, 23GR...Right side third rotor, rotor 23L, 23GL...Left third rotor, rotor 25…Blade 30...Surface of revolution 161... Data for calculating rotation speed (first data) 162...Pitch angle calculation data (second data) 210, 210G...First rotor group 220, 220G...Second rotor group 230, 230G...Third rotor group

Claims

1. A pair of left and right rod-shaped support members extending in the front-rear direction and provided on both left and right sides; A propulsion propeller; Two or more rotors for vertical lifting are arranged in the front-rear 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; a control unit that 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 that represents a ratio between a flight speed and a tip speed of the rotor such that an effective lift-to-drag ratio of the rotor is equal to or greater than a threshold value; A vertical take-off and landing aircraft equipped with:

2. 2. The vertical take-off and landing aircraft of claim 1, The control unit is acquiring flight speed information of the vertical take-off and landing aircraft; using the flight speed information, and based on first data prepared in advance that indicates a relationship between an effective lift-to-drag ratio of the rotor and the forward advance rate, calculating a range of rotation speeds of the rotor such that the forward advance rate is such that the effective lift-to-drag ratio of the rotor is equal to or greater than a threshold; using the flight speed information to calculate a range of pitch angles of the blades that will generate a required lift for the rotor within the calculated range of rotor rotation speeds; The rotation speed of the rotor and the pitch angle of the blades are determined within the calculated range of the rotation speed of the rotor and the calculated range of the pitch angle of the blades. Vertical take-off and landing aircraft.

3. 3. The vertical take-off and landing aircraft of claim 2, The control unit is acquiring attitude information of the vertical take-off and landing aircraft; Taking into account the attitude information, the rotor speed and the blade pitch angle are determined. Vertical take-off and landing aircraft.

4. 3. The vertical take-off and landing aircraft of claim 2, a storage device that stores the first data and second data indicating a relationship between the rotation speed of the rotor, the pitch angle of the blades, and an effective lift-drag ratio of the rotor for each flight speed, the first data being prepared in advance; The control unit is In calculating the rotation speed of the rotor, using the flight speed information and based on the first data, calculating a range of the rotation speed of the rotor at a forward rate at which an effective lift-to-drag ratio of the rotor is equal to or greater than a threshold; In calculating the range of the pitch angle of the blades, the flight speed information is used based on the second data to calculate the range of the pitch angle of the blades that generates a necessary lift for the rotor within the calculated range of the rotor rotation speed. Vertical take-off and landing aircraft.

5. 2. The vertical take-off and landing aircraft of claim 1, The advance ratio at which the effective lift-drag ratio of the rotor is equal to or greater than a threshold is 0.5 or more. Vertical take-off and landing aircraft.

6. 3. The vertical take-off and landing aircraft of claim 2, The rotors are arranged on each of the rod-shaped support members in the same number so as to form a plurality of rotor groups each including a pair of left and right rotors; The control unit controls a rotation speed of a rotor belonging to one of the plurality of rotor groups so as to be different from a rotation speed of a rotor belonging to another rotor group under a condition that the rotation speed of each of the rotors is within the range of the calculated rotor rotation speed. Vertical take-off and landing aircraft.

7. 2. The vertical take-off and landing aircraft of claim 1, The control unit controls the rotation speed of the rotor and the pitch angle of the blades so that a forward rate is reached at which an 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. Vertical take-off and landing aircraft.

8. 8. A vertical take-off and landing aircraft as claimed in claim 7, The predetermined speed is 100 km / h. Vertical take-off and landing aircraft.

9. 2. The vertical take-off and landing aircraft of claim 1, The control unit rotates the two rotors, whose centers are adjacent to each other in the front-rear direction on the same straight line parallel to the front-rear direction during forward flight, so that their rotation directions are opposite to each other. Vertical take-off and landing aircraft.

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

11. 2. The vertical take-off and landing aircraft of claim 1, Among 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 are positioned such that the center of one rotor is shifted in the left-right direction from the center of the other rotor. Vertical take-off and landing aircraft.

12. 12. The vertical take-off and landing aircraft of claim 11, The rotors are arranged in three on each of the rod-shaped support members so that the rotors are positioned at the same vertical position, the three rotors disposed on the right rod-shaped support member are a right first rotor, a right second rotor, and a right third rotor arranged in this order from front to rear, the three rotors disposed on the left rod-shaped support member are a left first rotor, a left second rotor, and a left third rotor arranged in this 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 by a radius of the rotation plane of the rotors, the left second rotor is positioned outward in the left-right direction from the left first rotor and the left third rotor by a radius of a rotation plane of the rotors, The control unit rotates the first right rotor, the second right rotor, and the third left rotor so that a rotation direction is counterclockwise when viewed from above, and rotates the third right rotor, the first left rotor, and the second left rotor so that a rotation direction is clockwise. Vertical take-off and landing aircraft.

13. 2. The vertical take-off and landing aircraft of claim 1, Three or more rotors are disposed on each of the rod-shaped support members. Vertical take-off and landing aircraft.

14. 14. The vertical take-off and landing aircraft of claim 13, The rotors are arranged on each of the rod-shaped support members in the same number so as to form a plurality of rotor groups each including a pair of left and right rotors; A rotor belonging to one of the rotor groups has a vertical position different from that of rotors belonging to the other rotor groups. Vertical take-off and landing aircraft.

15. 15. A vertical take-off and landing aircraft as claimed in claim 14, 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 front-rear direction in a plan view, the three rotors disposed on the right rod-shaped support member are a right first rotor, a right second rotor, and a right third rotor arranged in this order from front to rear, the three rotors disposed on the left rod-shaped support member are a left first rotor, a left second rotor, and a left third rotor arranged in this 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 first right rotor, the third right rotor, and the second left rotor so that their rotation direction is counterclockwise when viewed from above, and rotates the second right rotor, the first left rotor, and the third left rotor so that their rotation direction is clockwise. Vertical take-off and landing aircraft.

16. 15. A vertical take-off and landing aircraft as claimed in claim 14, 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 front-rear direction in a plan view, the three rotors disposed on the right rod-shaped support member are a right first rotor, a right second rotor, and a right third rotor arranged in this order from front to rear, the three rotors disposed on the left rod-shaped support member are a left first rotor, a left second rotor, and a left third rotor arranged in this 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 first right rotor, the second right rotor, and the third left rotor so that their rotation direction is counterclockwise when viewed from above, and rotates the third right rotor, the first left rotor, and the second left rotor so that their rotation direction is clockwise. Vertical take-off and landing aircraft.

17. 2. The vertical take-off and landing aircraft of claim 1, The torso and a fixed wing extending in the left-right direction and coupled to the fuselage and connecting the pair of left and right rod-shaped support members; A vertical take-off and landing aircraft further comprising:

18. 18. A vertical take-off and landing aircraft as claimed in claim 17, A rotor blade that is disposed on the fixed blade and generates harmonic vibration in the opposite phase to the vibration originating from the rotor. A vertical take-off and landing aircraft further comprising:

19. 2. The vertical take-off and landing aircraft of claim 1, The rotor is disposed below the rod-shaped support member. Vertical take-off and landing aircraft.

20. 2. The vertical take-off and landing aircraft of claim 1, a vertical stabilizer disposed aft of the lower portion of the rod-like support member and extending downward; The tip of the vertical stabilizer is located below the rotation plane of the propulsion propeller. Vertical take-off and landing aircraft.

21. 2. The vertical take-off and landing aircraft of claim 1, The control unit controls the rotor located at the front during forward flight so that the rotation plane of the rotor is inclined forward with respect to the traveling direction, so that the rotor functions for propulsion in addition to or instead of the propulsion propeller. Vertical take-off and landing aircraft.

22. 2. The vertical take-off and landing aircraft of claim 1, The control unit controls the rotation speed 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. Vertical take-off and landing aircraft.

23. 2. The vertical take-off and landing aircraft of claim 1, The rotors are arranged on each of the rod-shaped support members in the same number so as to form a plurality of rotor groups each including a pair of left and right rotors; The number of blades of a rotor belonging to one of the rotor groups is different from the number of blades of a rotor belonging to another rotor group. Vertical take-off and landing aircraft.

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