JP6784391B2 - Compound helicopter - Google Patents

Description

The present invention relates to a compound helicopter.

The helicopter has the advantage of being able to hover, but has the disadvantage of having a low top speed. Research and development for speeding up has been carried out for a long time, and Westland Lynx (Non-Patent Document 1) in the United Kingdom, which adopted the usual helicopter format, recorded a speed of 400.87 km / h in 1986. In 2010, the US Sikorsky X2 recorded 460 km / h, and in 2013, the European Eurokopter X3 recorded 473 km / h.

There are two factors that prevent the helicopter from speeding up. One is that the flow velocity of the air that hits the rotating rotor blade becomes sound velocity near the azimuth angle of 90 degrees (the rotor blade azimuth angle starts from the rear and the rotor blade rotation direction is positive) where the forward speed and the blade rotation speed are added. This is because the resistance rapidly increases due to the influence of compressibility (hereinafter referred to as resistance divergence), which consumes a large amount of power. This is because the region of backflow near the degree expands as the velocity increases, making it difficult to generate lift.

As a means to solve these problems, devise the shape of the blade tip and means to generate forward thrust by a jet engine or propeller for propulsion without relying on the forward tilt component of lift due to the forward tilt of the rotor rotating surface (compound method). There is. As the former, BERP (Patent Document 1) of Westland Lynx is known. BERP suppresses resistance divergence by giving a receding angle to the tip of the rotor blade, increases the chord length of the tip to increase the wing area, and provides an overhang that acts as a dog tooth at the starting point of the receding angle. It is devised so that a vertical vortex can be positively generated and a large lift can be generated at the tip on the backward side (around 270 degrees azimuth). The latter is an old concept, and in 1957, Fairey Rotodyne (Non-Patent Document 2) of the United Kingdom flew in the form of equipped with two propellers for propulsion on the left and right sides of the fuselage in addition to the main rotor. The aforementioned Sikorsky X2 is equipped with a coaxial counter-rotating rotor and a pusher-type propeller. In addition to the normal main rotor, the Eurokopter X3 is equipped with main wings and two propulsion propellers on both sides of the fuselage (Patent Document 2).

The Eurokopter X3 reduces the rotor speed by 15% during high-speed flight to suppress the resistance divergence of the forward blade, and also generates 70% of the lift on the main wing to reduce the load on the rotor and transmit excess power to the propeller.

The Sikorsky X2 uses a technique called ABC (Advancing Blade Concept) that reduces the rotor speed during high-speed flight to suppress resistance divergence of the forward rotor blades, and bears lift only on the forward side (Patent Document 3). When lift is applied only on the forward side with a normal articulated rotor or rigid rotor, the position where the flapping angle is maximized is delayed by 70 to 90 degrees due to the gyroscopic presession. As a result, the rotor rotating surface tilts backward and a head-raising moment is generated. In ABC, the flapping hinge of the rotor is made extremely rigid and the phase delay of flapping due to the gyroscopic presession is made as close to 0 as possible to generate a roll moment without generating a head raising moment. Furthermore, this roll moment is canceled between the upper and lower rotors by adopting a coaxial counter-rotating rotor.

As described above, as a technique for increasing the speed of the helicopter, the compound method, ABC, BERP, the reduction in the number of revolutions, and the lift load by the main wing have been put into practical use. Of these, Sikorsky X2 uses ABC, compound method, and reduction in rotation speed, but it can be expected to increase speed by combining BERP and the lift load of the main wing.

U.S. Pat. No. 5,174,721 U.S. Pat. No. 2009/0321554 U.S. Pat. No. 3,409,249

Jane's all the world's aircraft 1986-1987, pp. 321. Jane's all the world's aircraft 1957-1958, pp. 77. Jane's all the world's aircraft 1992-1993, pp. 390.

The Sikorsky X2 has achieved high-speed performance by using ABC, compound method, and rotation speed reduction, but ABC has the following problems.
-In order to realize an extremely rigid rotor blade, the thickness of the blade base becomes large, which is aerodynamically disadvantageous.
-Since an extremely rigid rotor blade is used, the bending moment generated by the rotor blade is transmitted to the airframe, which causes large vibration and extremely poor riding comfort.
-Since an extremely rigid rotor blade is used, the blade does not flap, so it is not possible to adjust the optimum front-back inclination of the rotor rotation surface according to the flight speed, and only the inclination of the rotor rotation surface perpendicular to the mounted rotor mast. Not available.
-In the coaxial counter-rotating rotor, it is necessary to separate the upper and lower rotors to some extent, and the air resistance of the rotor mast between the rotors is large, which hinders high-speed performance.
-There are only a limited number of companies that have put coaxial counter-rotating rotors into practical use, and especially the design of swash plates requires high technology.
-Since the swash plate for the coaxial counter-rotating rotor is complicated, it is expensive and has poor maintainability.

Therefore, an object of the present invention is to provide a compound helicopter capable of exhibiting high-speed performance without using an extremely rigid rotor blade and a coaxial counter-rotating rotor.

In order to achieve the above object, the helicopter according to one embodiment of the present invention includes a cross-type counter-reversing rotor, a thrust generating unit that generates thrust other than the respective rotors of the cross-type counter-rotor, and the rotor. A mechanism that controls the cyclic pitch so that the lift generated by the rotor blades is maximized at the azimuth angle of the rotor blades that minimizes the power for rotation, and the head-raising moment generated by the lift generated by the rotor blades. It is equipped with a horizontal tail that generates lift to cancel.

The mechanism for controlling the cyclic pitch maximizes the lift generated by the rotor blades at a speed of 50 m / s or higher at the azimuth angle of the rotor blades that minimizes the power for rotation of the rotor. It is preferable to control the cyclic pitch as described above.

It is preferable to reduce the rotation speed of the rotor blade during high-speed flight so that the tip speed of the rotor blade does not exceed the speed of sound.

The horizontal stabilizer is a fully floating horizontal stabilizer, and lift is generated to cancel the head-raising moment by increasing the mounting angle of the horizontal stabilizer constituting the fully floating horizontal stabilizer or lowering the elevator. It is preferable to do so.

The thrust generating portion is preferably one pusher type propeller arranged at the tail or propellers arranged on the left and right sides of the fuselage.

The rotor is preferably of a fully articulated, semi-rigid, or rigid type with a hinge offset or equivalent hinge offset of 3% to 20%.

The number of rotor blades of each of the rotors is preferably 2 to 4 per side of the rotor, and more preferably 3 per side of the rotor.

The crossing angle of the rotor mast on which each of the cross-rotating rotors is arranged is preferably 5 to 40 degrees.

According to the present invention, high-speed performance can be exhibited without using an extremely rigid rotor blade and a coaxial counter-rotating rotor. Therefore, it is necessary to realize a compound helicopter with a simple configuration, low cost, which can suppress the deterioration of riding comfort as much as possible, suppress the resistance of the rotor mast, and exhibit high-speed performance with versatile technology. Can be done.

It is a perspective view of the compound helicopter which concerns on one Embodiment of this invention. It is a front view of the compound helicopter shown in FIG. It is a top view of the compound helicopter shown in FIG. It is a side view of the compound helicopter shown in FIG. It is a graph which shows the schedule of the blade tip speed and the vertical rotor rotation surface which concerns on one Embodiment of this invention. It is a graph which shows the control amount at the time of the balanced flight which concerns on one Embodiment of this invention. It is a graph which shows the required power at the time of the balanced flight which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a compound helicopter according to an embodiment of the present invention. 2, FIG. 3 and FIG. 4 are a front view, a top view and a side view of the compound helicopter, respectively.
As shown in these figures, the compound helicopter 1 has a cross-rotating rotor 10, a pusher-type propeller 20 as a thrust generator, and a horizontal stabilizer 30.
The compound helicopter 1 further includes a main wing 41, a vertical tail 42, a main wheel 43, a main landing gear 44, a tail wheel 45, an air intake 46, a canopy 47, and the like.

The cross-rotating rotor 10 is composed of a right rotor 12 disposed on the right rotor mast 11 and a left rotor 14 disposed on the left rotor mast 13. Each rotor 12 and 14 has a rotor blade 15.

Here, the rotors 12 and 14 are full-joint, semi-rigid, or rigid with a hinge offset or equivalent hinge offset of 3% to 20%.
The crossing angle of the rotor mast on which the rotors 12 and 14 of the cross-rotating rotor 10 are arranged is in the range of 5 to 40 degrees.
The number of rotor blades 15 of each of the rotors 12 and 14 is preferably 2 to 4 per side of the rotors 12 and 14, and more preferably 3 per side of the rotors 12 and 14.
The compound helicopter 1 is configured to reduce the rotation speed of the rotor blade 15 during high-speed flight so that the tip speed of the rotor blade 15 does not exceed the speed of sound.

The compound helicopter 1 typically produces lift at a speed of 50 m / s or higher at the azimuth angle of the rotor blade 15 that minimizes the power for rotation of the rotors 12 and 14. 16 has a mechanism 16 for controlling the cyclic pitch so that Since this mechanism 16 is the same as the mechanism of a general helicopter, the description thereof will be omitted here.

One pusher-type propeller 20 is mounted on the tail of the compound helicopter 1. As the thrust generating portion, propellers or the like arranged on the left and right sides of the fuselage, such as Eurocopter X3, may be typically used.

The horizontal stabilizer 30 is typically composed of a fully floating horizontal stabilizer. The fully floating horizontal stabilizer is a tail in which the elevator and the horizontal stabilizer are not separated and the mounting angle of the horizontal stabilizer is changed to serve as the control surface.
In this embodiment, by increasing the mounting angle of the horizontal stabilizer 30 of the horizontal stabilizer 30, lift is generated that cancels the lift moment generated by the cyclic pitch control that maximizes the lift. By lowering the rudder of the elevator, lift may be generated to cancel this head-raising moment.

The configuration of the compound helicopter 1 does not prevent the combined use with the lift load by the main wing 41 during high-speed flight.
In this compound helicopter 1, normal cyclic pitch control is performed at low speed, but at speeds of 50 m / s or higher, cyclic pitch control is performed so that the rotor blade 15 generates maximum lift near an azimuth angle of 90 degrees. .. The head-raising moment generated by this is canceled by increasing the mounting angle of the horizontal stabilizer constituting the fully floating horizontal stabilizer 30 or lowering the elevator to generate lift on the horizontal stabilizer 30.

Further, as the rotors 12 and 14, a full-joint type, semi-rigid type or rigid rotor having a hinge offset or an equivalent hinge offset of 3% to 20% is used. The rotation speed is reduced during high-speed flight so that the tip speed of the rotor blade 15 on the forward side is equal to or lower than the speed of sound. As the rotors 12 and 14, a cross-type counter-rotor 10 such as the Flettner Fl-282 and Kaman K-MAX (Non-Patent Document 3) used in Germany during World War II is used. It takes the form of a compound helicopter 1 that obtains propulsion by a pusher-type propeller 20 at the tail.

There is no backflow region on the forward side of the rotor blade 15 (around 90 degrees azimuth), and it is exposed to the airspeed, which is the sum of the forward speed and the rotation speed, and there is no risk of stall. Resistance divergence on the forward side becomes a problem during high-speed flight, but this problem can be avoided by reducing the number of revolutions so that the tip of the rotor blade 15 does not exceed the speed of sound during high-speed flight. During high-speed flight, lift is borne at the optimum position near the forward side of the rotor blade 15. As a result, the rotating surfaces of the rotors 12 and 14 are tilted backward or to the left or right, the head-raising moment generated by the former is canceled by the lift generated by the horizontal stabilizer 30, and the rollover moment generated by the latter is the symmetrical rotor on the left and right. It is canceled by 12 and 14.

In this compound helicopter 1, since a general flapping hinge is used, it is not necessary to increase the thickness of the roots of the rotors 12 and 14 to increase the rigidity, and an aerodynamically advantageous thin blade cross section can be used.

Since the rotor blade 15 can be flapping, the front-back inclination of the rotor rotating surface can be adjusted to be optimum according to the flight speed, and the rotating surface can be slightly tilted backward, which is advantageous for the compound rotor during high-speed flight. ..
Further, the bending moment generated in the rotor blade 15 is less likely to be transmitted, and the riding comfort is improved.
In the coaxial counter-rotating rotor, there is a risk of contact between the upper and lower rotor blades 15, but this can be avoided by using the cross-rotating rotor 10.
During forward flight, the rotor blade 15 generates lift enough to support its own weight, and a high speed can be obtained by adopting a compound method in which the propulsive force is generated by the pusher type propeller 20 for propulsion. Both the rotor head and the swash plate can be manufactured by diverting general helicopter technology. The exposed rotor masts 11 and 13 can be made shorter than the coaxial counter-rotating helicopter, and the resistance can be reduced.
<Example>
An example of the compound helicopter 1 is shown below.

ヒンジオフセットがある場合、２枚ロータブレード１５のロータ１２、１４のロータ回転面が傾くと一回転につき２回のモーメントの脈動が生じる。３枚ロータブレード１５とすれば理論的にモーメントの脈動は消えるため３枚ロータブレード１５が好ましい。ロータブレード１５の枚数は一般に多いほど機体の振動は小さくなるが、交差式二重反転ロータ１０では４枚ロータブレード１５までが、お互いのロータブレード１５の干渉を避けることができる限界である。

When there is a hinge offset, when the rotor rotating surfaces of the rotors 12 and 14 of the two rotor blades 15 are tilted, pulsation of two moments occurs per rotation. If the three rotor blades 15 are used, the pulsation of the moment disappears theoretically, so the three rotor blades 15 are preferable. Generally, the larger the number of rotor blades 15, the smaller the vibration of the machine body. However, in the cross-rotating rotor 10, up to four rotor blades 15 are the limits at which interference between the rotor blades 15 can be avoided.

If the pusher type propeller 20 has an absorption horsepower of 1000 kW, a diameter slightly larger than 3 m is suitable, but the diameter is limited in order to secure clearance with the ground. Further, in order to prevent the propeller 20 from coming into contact with the ground, the vertical stabilizer 42 is attached downward, and the tail wheel 45 is attached to the tip. The main landing gear 44 will be long to secure the propeller clearance, but a fixed wing will be attached to store it, and it will be retractable inward. Since the rotor rotating surfaces are each tilted 15 degrees outward, a long main landing gear 44 is required to prevent contact with the ground.

Fixed wings are inevitably required for retracting the main landing gear, but by making them bear the lift during high-speed flight, the lift burden on the rotors 12 and 14 can be reduced. Since the main wing 41 is located near the center of gravity, it is preferable to equip it to secure a space for storing the fuel tank.

In the low speed range, the tip speed _VTIP of the rotor blade 15 is set to 200 m / s (absolute minimum speed of the helicopter), the flight speed is gradually reduced from 80 m / s to 130 m / s, and the _VTIP is 160 m / s at the flight speed of 130 m / s or higher. Make it constant with s.

Further, in the low speed range, the rotor blade 15 uniformly bears the lift in all azimuth angles, but the rotor rotating surface is gradually tilted backward from the flight speed of 80 m / s to 120 m / s. Here, the first-order Fourier series expansion formula of the blade flapping angle β, which is customarily used to express the inclination of the rotor surface of revolution,
β = a ₀ -a ₁ cosΨ-b ₁ sinΨ (Equation 1)
Gradually increased the coefficient a ₁ of the cosine. Where Ψ is the azimuth.

A ₁ representing the anteroposterior inclination of the rotor rotating surface is set to 0 in the low speed range, but the flight speed is gradually increased from 80 m / s to 120 m / s, and is constant at 1.8 degrees at a flight speed of 120 m / s or more. Also, b ₁ representing the left-right inclination is always 0. This control is shown graphically in FIG.

Generally, the blade mounting angle θ is expressed by the following equation based on the convention.

θ = θ ₀ -A ₁ cosΨ-B ₁ sinΨ (Equation 2)
Here, θ ₀ , A ₁ , and B ₁ are control quantities. Further, in addition to the usual control amounts, in the embodiment, the horizontal stabilizer 30 is a fully floating type, and the mounting angle θ _T thereof is also a control amount.

When a mathematical model of the aircraft of the form shown in FIGS. 1 to 4 having the specifications of Table 1 was created and the flight speed was gradually increased from 0 speed, balanced flight was achieved up to 150 m / s (540 km / h). It was possible. The change in the controlled variable at this time is shown in FIG. The horizontal stabilizer attachment angle θ _T has a large value at low speeds, because the wind hits the horizontal stabilizer 30 from diagonally above due to the blow-down created by the main rotor, and the horizontal stabilizer 30 generates lift at low speeds. Not done. At high speeds, the head-raising moment created by the rotor head, the resistance acting on the rotor head, and the head-raising moment created by the combined force of lift increase, and this is canceled by the head-lowering moment created by the lift of the horizontal stabilizer 30.

FIG. 7 shows changes in the power _PROTOR required to rotate the rotors 12 and 14, the power P _PROP required to generate the thrust commensurate with the resistance of the rotors 12 and 14 and the airframe with the propeller 20, and the total P _TOTAL of these. Shown in. The reason why _PROTOR gradually decreases is that the amount of air flowing into the region affected by the rotor increases per unit time, so that the blow-down speed decreases and the rotation speed decreases from the flight speed of 80 m / s. Further, since the rotor rotating surface is tilted backward, a rotating force like an autogyro is applied to the rotor blade 15. The power P _PROP absorbed by the propeller 20 increased sharply with the flight speed, but the total power was still below the maximum output of 1150 kW even at 150 m / s. The maximum speed was determined by the ability to fly in a balanced manner and was 150 m / s (540 km / h).

The compound helicopter 1 according to the present invention can be used as a passenger helicopter, an observation helicopter, a rescue helicopter, or the like.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made.

1 Compound helicopter 10 Cross-type counter-rotor 11 Right rotor mast 12 Right rotor 13 Left rotor mast 14 Left rotor 15 Rotor blade 16 Mechanism for controlling cyclic pitch 20 Pusher type propeller 30 Horizontal tail

Claims (9)

Cross-rotating rotor and
Thrust generating parts that generate thrust other than the respective rotors of the cross-rotating rotor,
A mechanism that controls the cyclic pitch so that the lift generated by the rotor blades is maximized at the azimuth angle of the rotor blades that minimizes the power for rotation of the rotor.
It is equipped with a horizontal stabilizer that generates lift that cancels the lift moment generated by the lift generated by the rotor blades .
The horizontal stabilizer is a compound helicopter located in front of the thrust generating portion . The compound helicopter according to claim 1.
The mechanism for controlling the cyclic pitch maximizes the lift generated by the rotor blades at a speed of 50 m / s or higher at the azimuth angle of the rotor blades, which minimizes the power for rotating the rotor. A compound helicopter that controls the cyclic pitch in this way. The compound helicopter according to claim 1 or 2.
A compound helicopter that lowers the rotation speed of the rotor blade during high-speed flight so that the tip speed of the rotor blade does not exceed the speed of sound. The compound helicopter according to any one of claims 1 to 3.
The horizontal stabilizer is a fully floating horizontal stabilizer, and lift is generated to cancel the head-raising moment by increasing the mounting angle of the horizontal stabilizer constituting the fully floating horizontal stabilizer or lowering the elevator. Compound helicopter. The compound helicopter according to any one of claims 1 to 4.
The thrust generating portion is a compound helicopter which is a pusher type propeller arranged at the tail. The compound helicopter according to any one of claims 1 to 5.
The rotor is a fully articulated, semi-rigid, or rigid compound helicopter with a hinge offset or equivalent hinge offset of 3% to 20%. The compound helicopter according to any one of claims 1 to 6.
The number of rotor blades of each of the rotors is 2 to 4 per side of the rotor compound helicopter. The compound helicopter according to claim 7.
The number of the rotor blades of each of the rotors is three per side of the rotor compound helicopter. The compound helicopter according to any one of claims 1 to 8.
A compound helicopter in which the intersecting angle of the rotor mast on which each of the cross-rotating rotors is arranged is 5 to 40 degrees.

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