Patent Description:
<CIT> discloses an aircraft referred to as a vertical take-off and landing (VTOL) aircraft. The aircraft disclosed in <CIT> includes a fuselage, a front wing and a rear wing (main wing) connected to the fuselage, a plurality of takeoff and landing rotors disposed on the left and right sides of the fuselage, and a plurality of cruise rotors disposed above the rear wing. This aircraft uses the takeoff and landing rotors during takeoff and landing and during hovering, and uses the cruise rotors during cruising. In addition, this aircraft uses both the takeoff and landing rotors and the cruise rotors when transitioning from hovering to cruising and when transitioning from cruising to hovering. Further reference shall be made to documents <CIT>, <CIT> and <CIT>, all of which disclose aircraft with VTOL capabilities.

Disposing a thrust device at the upper portion of the wing has disadvantages in aerodynamic design. For this reason, it is preferable to dispose the thrust device at the lower portion of the wing. However, in the aircraft disclosed in <CIT>, if the thrust device is disposed at the lower portion of the rear wing, the following problem may occur.

In the aircraft disclosed in <CIT>, the takeoff and landing rotors are disposed forward of the cruise rotors in plan view. A pair of takeoff and landing rotors disposed forward of the cruise rotors cause air to flow downward. The air generated at this time interferes with the air guided from the front to the cruise rotors. Then, there is a possibility that disturbance occurs in the flow of the air guided to the cruise rotors and the thrust generated by the cruise rotors is affected.

On the other hand, if the cruise rotors are disposed on the fuselage side, the fuselage is positioned forward of the cruise rotors. Then, the fuselage may obstruct the flow of the air guided to the cruise rotors. In this case, sufficient thrust cannot be generated by the cruise rotors.

The present invention has been made in view of such a problem, and an object thereof is to provide an aircraft capable of sufficiently obtaining thrust generated by cruise rotors.

According to an aspect of the present invention, there is provided an aircraft according to appended claim <NUM>.

According to the present invention, it is possible to sufficiently obtain the thrust generated by the cruise rotors.

A preferred embodiment of an aircraft according to the present invention will be presented and described in detail below with reference to the accompanying drawings.

In the present embodiment, an aircraft <NUM> is assumed to be an electric vertical take-off and landing (eVTOL) aircraft that generates lift and thrust using rotors each including an electric motor. In this specification, a vertically upward direction is referred to as an upward direction (upward), and a vertically downward direction is referred to as a downward direction (downward). Further, a moving direction of the aircraft <NUM> when the aircraft <NUM> moves (flies) in the horizontal direction is referred to as a forward direction (forward), and a direction opposite thereto is referred to as a rearward direction (rearward). Further, in a state of facing forward from the aircraft <NUM>, a direction toward the right side in the width direction of the aircraft <NUM> is referred to as a right direction (rightward), and a direction toward the left side in the width direction is referred to as a left direction (leftward). Further, the plan view of the aircraft <NUM> refers to a view in which the respective components are viewed from a position directly above the aircraft <NUM>. The front view of the aircraft <NUM> refers to a view in which the respective components are viewed from a position in front of the aircraft <NUM>.

The aircraft <NUM> includes a fuselage <NUM>, a front wing <NUM>, a rear wing <NUM>, two booms <NUM>, eight takeoff and landing rotors <NUM>, and two cruise rotors <NUM>. As shown in <FIG>, the structure of the aircraft <NUM> in plan view is bilaterally symmetrical about a position overlapping a central axis A of the fuselage <NUM> extending in the front-rear direction. In plan view, the central axis A overlaps a center of gravity G of the aircraft <NUM>.

The fuselage <NUM> is long in the front-rear direction. The fuselage <NUM> includes a front portion 12f located forward of the center of gravity G, and a rear portion 12r located rearward of the center of gravity G. The front portion 12f is configured such that the front end thereof is narrow. The rear portion 12r is configured such that the rear end thereof is narrow. The main body of the fuselage <NUM> may be partially covered with a fairing. In this specification, the fuselage <NUM>, the front portion 12f, and the rear portion 12r are referred to as such, including the fairing.

The front wing <NUM> is connected to an upper portion of the front portion 12f of the fuselage <NUM> and is configured to generate lift when the aircraft <NUM> moves forward. The front wing <NUM> includes a front wing main body (also referred to as a horizontal stabilizer) <NUM> extending to the left and right (laterally) from the center, and left and right elevators <NUM> disposed at the trailing edge of the front wing <NUM>.

The rear wing <NUM> is connected to an upper portion of the rear portion 12r of the fuselage <NUM> via a pylon <NUM> and is configured to generate lift when the aircraft <NUM> moves forward. The rear wing <NUM> includes a rear wing main body <NUM> extending laterally rearward from the center, left and right elevons <NUM> disposed at the trailing edge of the rear wing <NUM>, and a pair of vertical tails <NUM> disposed at left and right wing tips of the rear wing <NUM>. Each vertical tail <NUM> includes a tail main body <NUM> (also referred to as a vertical stabilizer), and a rudder <NUM> disposed at the trailing edge of the vertical tail <NUM>.

The wing area of the rear wing <NUM> is larger than the wing area of the front wing <NUM>. Further, the wing width of the rear wing <NUM> is greater than the wing width of the front wing <NUM>. With such a configuration, when the aircraft <NUM> moves forward, the lift generated by the rear wing <NUM> is larger than the lift generated by the front wing <NUM>. That is, the rear wing <NUM> functions as a main wing of the aircraft <NUM>. The rear wing <NUM> is a swept wing that reduces air resistance. On the other hand, the front wing <NUM> functions as a canard of the aircraft <NUM>. The front wing <NUM> and the rear wing <NUM> also function as support members for supporting the two booms <NUM>.

Note that the lift generated by the rear wing <NUM> when the aircraft <NUM> moves forward and the lift generated by the front wing <NUM> when the aircraft <NUM> moves forward may be substantially the same. The magnitude relationship between the lift generated by the front wing <NUM> and the lift generated by the rear wing <NUM> is appropriately determined depending on the position of the center of gravity G, the attitude of the fuselage during cruising, and the like. Further, the size (the wing area, the length, and the like) of each of the front wing <NUM> and the rear wing <NUM> is determined so as to generate a desired lift.

The two booms <NUM> include a right boom <NUM> disposed on the right side of the fuselage <NUM>, and a left boom <NUM> disposed on the left side of the fuselage <NUM>. The two booms <NUM> form a pair and are arranged so as to be bilaterally symmetrical about a position overlapping the central axis A of the fuselage <NUM> in plan view. The two booms <NUM> function as support members for supporting the takeoff and landing rotors <NUM>.

The right boom <NUM> is a bar member that extends from the front toward the rear and is curved rightward (outward in the width direction) in an arc shape. The right boom <NUM> is connected to the right wing tip of the front wing <NUM> and is connected to the right wing of the rear wing <NUM> on the inner side of the elevon <NUM>. The front end of the right boom <NUM> is located forward of the front wing <NUM>. The rear end of the right boom <NUM> is located rearward of the rear wing <NUM>.

The left boom <NUM> is a bar member that extends from the front toward the rear and is curved leftward (outward in the width direction) in an arc shape. The left boom <NUM> is connected to the left wing tip of the front wing <NUM> and is connected to the left wing of the rear wing <NUM> on the inner side of the elevon <NUM>. The front end of the left boom <NUM> is located forward of the front wing <NUM>. The rear end of the left boom <NUM> is located rearward of the rear wing <NUM>.

The takeoff and landing rotors <NUM> each include a rotating mast (not shown) connected to an output shaft of an electric motor (not shown), and a propeller <NUM> attached to the rotating mast. The rotating mast is disposed so as to be parallel to the up-down direction and is rotatable about an axis extending in the up-down direction. The propeller <NUM> is located above the boom <NUM>, the front wing <NUM>, and the rear wing <NUM>. With such a structure, the propeller <NUM> is rotatable about an axis extending in the up-down direction. Each takeoff and landing rotor <NUM> generates lift by rotation of the propeller <NUM>.

The eight takeoff and landing rotors <NUM> include four takeoff and landing rotors 20a to 20d disposed on the right side of the fuselage <NUM>, and four takeoff and landing rotors 20a to 20d disposed on the left side of the fuselage <NUM>. The right-side takeoff and landing rotors 20a to 20d are supported by the right boom <NUM>. The left-side takeoff and landing rotors 20a to 20d are supported by the left boom <NUM>. Each of the right-side takeoff and landing rotors 20a to 20d and each of the left-side takeoff and landing rotors 20a to 20d form a pair, the position of each right-side takeoff and landing rotor and the position of the left-side takeoff and landing rotor paired with this right-side takeoff and landing rotor being the same in the front-rear direction.

As shown in <FIG>, the pair of takeoff and landing rotors 20a, the front wing <NUM>, the pair of takeoff and landing rotors 20b, the pair of takeoff and landing rotors 20c, the rear wing <NUM>, and the pair of takeoff and landing rotors 20d are arranged in this order from the front toward the rear in plan view. In other words, the pair of takeoff and landing rotors 20a are disposed forward of the front wing <NUM>. Further, the pair of takeoff and landing rotors 20b are disposed between the front wing <NUM> and the rear wing <NUM>, and are disposed forward of the pair of takeoff and landing rotors 20c. Furthermore, the pair of takeoff and landing rotors 20c are disposed between the front wing <NUM> and the rear wing <NUM>, and are disposed rearward of the pair of takeoff and landing rotors 20b. The pair of takeoff and landing rotors 20d are disposed rearward of the rear wing <NUM>.

The two cruise rotors <NUM> are disposed on the rear portion 12r of the fuselage <NUM>. The position of each cruise rotor <NUM> in the left-right direction is on the inner side (the fuselage <NUM> side) of the position of each pair of takeoff and landing rotors <NUM> in the left-right direction. Further, the position of each cruise rotor <NUM> in the front-rear direction is between the pair of takeoff and landing rotors 20c and the pair of takeoff and landing rotors 20d. Furthermore, the position of the axis of each cruise rotor <NUM> in the up-down direction is lower than the position of the propeller <NUM> of each takeoff and landing rotor <NUM> in the up-down direction.

As shown in <FIG>, the cruise rotors <NUM> each include a rotating mast (not shown) connected to an output shaft of an electric motor (not shown), a propeller <NUM> attached to a front end portion of the rotating mast, and a cylindrical duct <NUM> surrounding the propeller <NUM>. The positions of the two cruise rotors <NUM> coincide with each other in both the front-rear direction and the up-down direction. Further, the two cruise rotors <NUM> are arranged side by side in the left-right direction. One of the cruise rotors <NUM> is disposed on the right side of a position overlapping the central axis A of the fuselage <NUM> in plan view, and is supported by the right wing of the rear wing <NUM>. The other cruise rotor <NUM> is disposed on the left side of the position overlapping the central axis A of the fuselage <NUM> in plan view, and is supported by the left wing of the rear wing <NUM>. The rotating mast is located below the rear wing <NUM> so as to be parallel to the front-rear direction, and is rotatable about an axis extending in the front-rear direction. With such a structure, the propeller <NUM> is rotatable about an axis extending in the front-rear direction. Each cruise rotor <NUM> generates thrust by rotation of the propeller <NUM>.

The ducts <NUM> each include a tubular portion <NUM> located on the outer side, a central portion <NUM> located on the center side, and a plurality of (three in the present embodiment) arms <NUM> extending in the radial direction of the duct <NUM> between the inner circumferential surface of the tubular portion <NUM> and the outer circumferential surface of the central portion <NUM>. The outer circumferential surface of the left tubular portion <NUM> and the outer circumferential surface of the right tubular portion <NUM> are connected to each other. The tubular portion <NUM> has a cylindrical shape centered on the rotating mast, and surrounds the propeller <NUM>. A recessed portion <NUM> extending in the front-rear direction, the left-right direction, and the up-down direction is formed in a portion rearward of the rear wing <NUM> and between the left and right elevons <NUM> and the left and right booms <NUM>. The tubular portions <NUM> of the ducts <NUM> are disposed inside the recessed portion <NUM>. However, the tubular portions <NUM> are separated from the recessed portion <NUM>. As shown in <FIG>, a protruding portion <NUM> that protrudes downward is formed in each of a lower portion of the left wing of the rear wing <NUM> and a lower portion of the right wing of the rear wing <NUM>. The central portion <NUM> of the duct <NUM> is connected to the protruding portion <NUM>.

As shown in <FIG>, in front view, a portion of the rear wing <NUM> overlaps a portion of each cruise rotor <NUM>. Further, in front view, an upper portion of each cruise rotor <NUM> protrudes above the rear wing <NUM>, and a central portion and a lower portion of each cruise rotor <NUM> protrude below the rear wing <NUM>.

Here, a positional relationship between the rear portion 12r of the fuselage <NUM> and the cruise rotors <NUM> will be described. As shown in <FIG>, in front view, at least a portion of the fuselage <NUM> overlaps at least a portion of each of the two cruise rotors <NUM>. The portions where the fuselage <NUM> and the two cruise rotors <NUM> overlap each other in front view are referred to as overlapping portions <NUM>.

As shown in <FIG> and <FIG>, the rear portion 12r includes inclined surfaces <NUM> inclined downward in a direction from the front to the rear, so that the areas of the overlapping portions <NUM> gradually decrease from the front toward the rear. The inclined surfaces <NUM> extend from the front side to the rear side and from the upper side to the lower side. The inclined surfaces <NUM> are formed at the upper right and upper left portions of the rear portion 12r with respect to the pylon <NUM>. The inclined surfaces <NUM> guide a part of the air flowing from the front to the rear above the fuselage <NUM>, to the cruise rotors <NUM>.

Each of the inclined surfaces <NUM> may be a flat surface or a curved surface. For example, in a cross section parallel to the front-rear direction and the up-down direction, the shape of the inclined surface <NUM> may be linear or may be curved downward. Further, in a cross section parallel to the left-right direction and the up-down direction, the shape of the inclined surface <NUM> may be linear or may be curved downward. If the inclined surface <NUM> is curved, it is preferable that the outer peripheral surface of the pylon <NUM> and the inclined surface <NUM> form a continuously curved shape in the cross section parallel to the left-right direction and the up-down direction.

The position of a rear end <NUM> of the inclined surface <NUM> in the up-down direction is lower than the position of the cruise rotor <NUM> in the up-down direction. On the other hand, the position of the rear end <NUM> of the inclined surface <NUM> in the front-rear direction is preferably rearward of or the same as the position of the cruise rotor <NUM> in the front-rear direction. However, the position of the rear end <NUM> of the inclined surface <NUM> in the front-rear direction may be forward of the position of the cruise rotor <NUM> in the front-rear direction. With this structure, a space without a shield is formed at a position immediately in front of the duct <NUM>.

As shown in <FIG> and <FIG>, in the present embodiment, the lower surface of the rear portion 12r of the fuselage <NUM> is inclined upward in a direction from the front to the rear. Therefore, the area of the cross section of the rear portion 12r of the fuselage <NUM> that is parallel to the left-right direction and the up-down direction gradually decreases from the front toward the rear. However, the lower surface of the rear portion 12r, together with the inclined surface <NUM>, may be inclined downward in the direction from the front to the rear, or may extend horizontally from the front to the rear.

The takeoff and landing rotors <NUM> are used when the aircraft <NUM> takes off, lands, and hovers. On the other hand, the cruise rotors <NUM> are used when the aircraft <NUM> is cruising. Further, the takeoff and landing rotors <NUM> and the cruise rotors <NUM> are used together when the aircraft <NUM> transitions from hovering to cruising and moves forward at a first speed (≥ <NUM>/h) or more and less than a second speed (> first speed). In this case, the usage rate of the cruise rotors <NUM> is gradually increased for acceleration. Since the lift generated by the wing increases with acceleration, the usage rate of the takeoff and landing rotors <NUM> is gradually decreased. For example, the usage rate of the takeoff and landing rotors <NUM> is decreased by decreasing the rotational speed of the takeoff and landing rotors <NUM> to reduce the lift. Alternatively, the usage rate of the takeoff and landing rotors <NUM> is decreased by changing the pitch angle of respective blades to reduce the lift.

In addition, the takeoff and landing rotors <NUM> and the cruise rotors <NUM> are used together when the aircraft <NUM> transitions from cruising to hovering and moves forward at a third speed (≥ <NUM>/h) or more and less than a fourth speed (> third speed). In this case, the usage rate of the cruise rotors <NUM> is gradually decreased for deceleration. Since the lift generated by the wing decreases with deceleration, the usage rate of the takeoff and landing rotors <NUM> is gradually increased. For example, the usage rate of the takeoff and landing rotors <NUM> is increased by increasing the rotational speed of the takeoff and landing rotors <NUM> to increase the lift. Alternatively, the usage rate of the takeoff and landing rotors <NUM> is increased by changing the pitch angle of respective blades to increase the lift.

The technical idea that can be grasped from the above embodiment will be described below.

According to the preceding description, the aircraft <NUM> includes: the fuselage <NUM>; the wing (the rear wing <NUM>) connected to the upper portion of the rear portion 12r of the fuselage <NUM>; and at least two cruise rotors <NUM> disposed on the right and left sides of the central axis A of the fuselage <NUM>, and configured to generate thrust when the aircraft moves in the horizontal direction, wherein at least a portion of the fuselage <NUM> and at least a portion of each of the two cruise rotors <NUM> overlap each other in the front view of the aircraft <NUM> to form the overlapping portion <NUM>, and the rear portion 12r of the fuselage <NUM> includes the inclined surface <NUM> that is inclined downward in the direction from the front to the rear, in a manner so that the area of the overlapping portion <NUM> gradually decreases from the front toward the rear.

In the above configuration, the fuselage <NUM> and the two cruise rotors <NUM> overlap each other in front view. That is, the two cruise rotors <NUM> are located close to the fuselage <NUM> side. Further, in the above configuration, the inclined surfaces <NUM> are formed on the rear portion 12r of the fuselage <NUM>. Since a space is formed immediately in front of the cruise rotors <NUM> by the inclined surfaces <NUM>, the rear portion 12r of the fuselage <NUM> does not obstruct the flow of the air guided to the cruise rotors <NUM>. Further, the inclined surfaces <NUM> smoothly guide the air flowing from the front to the rear around the upper side of the fuselage <NUM>, to the cruise rotors <NUM>. Therefore, since air is sufficiently guided to the cruise rotors <NUM>, sufficient thrust can be generated by the cruise rotors <NUM>.

In the aspect of the present invention, the rear portion 12r of the fuselage <NUM> may extend to the position below the two cruise rotors <NUM>.

According to the above configuration, air flowing from the front can be guided to the cruise rotors <NUM>. Therefore, thrust can be efficiently generated.

In the aspect of the present invention, the rear portion 12r of the fuselage <NUM> may have a cross section that is parallel to the left-right direction and the up-down direction, and the area of the cross section may gradually decrease from the front toward the rear.

According to the above configuration, the shape of the fuselage <NUM> enables air flowing from the front to be guided to the cruise rotors <NUM>. Therefore, thrust can be efficiently generated.

According to the presently claimed invention, the two cruise rotors <NUM> are connected to the wing (the rear wing <NUM>) at positions rearward of the wing, whereby at least a portion of the wing and at least a portion of each of the two cruise rotors <NUM> overlap each other in the front view of the aircraft <NUM>, and the center of each of the cruise rotors <NUM> may be located below the wing.

According to the above configuration, since the portion of the cruise rotor <NUM> that protrudes above the wing (the rear wing <NUM>) is smaller than the portion of the cruise rotor <NUM> that protrudes below the wing, it is possible to reduce the resistance force generated in the cruise rotor <NUM>.

In the aspect of the present invention, the two cruise rotors <NUM> may each include the propeller <NUM> and the duct <NUM> configured to surround the propeller <NUM>, and the ducts <NUM> of the two cruise rotors <NUM> may be connected to each other.

According to the above configuration, since one of the cruise rotors <NUM> is connected to the wing (the rear wing <NUM>) and the other of the cruise rotors <NUM>, the rigidity of the cruise rotors <NUM> and the wing is increased.

In the aspect of the present invention, the aircraft may include the plurality of takeoff and landing rotors <NUM> configured to generate lift, and at least some takeoff and landing rotors (the takeoff and landing rotors 20d) among the plurality of takeoff and landing rotors <NUM> may be disposed rearward of the at least two cruise rotors <NUM>.

According to the above configuration, the flow of air generated by the takeoff and landing rotors 20d disposed rearward of the cruise rotors <NUM> does not interfere with the flow of air guided to the cruise rotors <NUM>. Therefore, the thrust generated by the cruise rotors <NUM> is not adversely affected.

In the aspect of the present invention, the wing (the rear wing <NUM>) may include the flight control surface (the elevon <NUM>) disposed on each of the right wing and the left wing thereof, and the two cruise rotors <NUM> may be arranged closer to the fuselage <NUM> than the flight control surface disposed on the right wing and the flight control surface disposed on the left wing are.

Claim 1:
An aircraft (<NUM>) comprising:
a fuselage (<NUM>);
a wing (<NUM>) connected to an upper portion of a rear portion (12r) of the fuselage; and
at least two cruise rotors (<NUM>) disposed on right and left sides of a central axis (A) of the fuselage, and configured to generate thrust when the aircraft moves in a horizontal direction,
wherein two cruise rotors among the at least two cruise rotors are supported by the wing at positions rearward of the wing,
in a front view of the aircraft, at least a portion of the wing and at least a portion of the two cruise rotors overlap each other,
at least a portion of the fuselage and at least a portion of each of the two cruise rotors overlap each other in a front view of the aircraft to form an overlapping portion (<NUM>), and
the rear portion of the fuselage includes an inclined surface (<NUM>) that is inclined downward in a direction from front to rear, in a manner so that an area of the overlapping portion gradually decreases from the front toward the rear.