JPH05178292A - Helicopter - Google Patents

Abstract

PURPOSE:To provide a helicopter which has a simple structure and can increase the lift of a blade, reduce the blade revolution torque, and improve fuel consumption. CONSTITUTION:The top edge part 6 of the blade 4 of a main rotor is bent upward to provide a dihedral angle. Accordingly, the blade edge vorgex generated at the blade top edge part of the preceding blade induces an air stream, and the inclined stream is introduced to the blade top edge having the dihedral angle of the succeeding blade, and a lift is generated at the blade top edge by this stream, and lift is generated by the winglet effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helicopter with improved lift in a main rotor.

[0002]

2. Description of the Related Art In a helicopter, a main rotor having a plurality of blades (blades) having a relatively large diameter is rotated by a substantially vertical main shaft so as to rotate these blades, and these blades make a downward velocity to air. It is known that the aircraft is capable of vertical lift, hovering, and forward flight by generating lift on the blade as a reaction.

A feature of a helicopter is that it can be stopped (hovering) in the air. However, at the time of hovering, there is a problem that the amount of fuel consumption is relatively large, even though the vehicle does not fly forward and merely stops in the air. If the fuel efficiency during hovering is improved, the fuel efficiency for the entire operation can be expected to be significantly improved.

By the way, in order to improve fuel economy, it is necessary to increase lift. As a means for this, research and development on the tip shape of the blade have been made conventionally. In other words, the rotation speed of the main rotor has a maximum speed at the blade tip (blade tip) of the blade, and the change in the shape of this portion greatly affects the lift performance.

[0005]

A blade tip shape of a conventional blade will be described with reference to FIGS. 6 to 8.

FIG. 6 shows an example of the most widely used rectangular blade. In this case, a blade tip vortex is generated in the vicinity of the blade tip of the blade 60, and this blade tip vortex causes induced resistance to cause large blade rotation. Requires torque.

FIG. 7 shows an example of a tapered blade, which is a blade 70.
The area on the tip side is gradually made smaller than that at the root. In this case, since the air load is reduced at the tip portion of the blade, the tip vortex can be weakened, and thus the induced resistance can be reduced. However, in this case, the blade 7
There is a drawback in that the lift is reduced as much as the area on the tip side of 0 is reduced. If you try to increase the angle of attack of the blade to compensate for this lift, resistance will increase, causing stall, etc.
After all, the result of lift rise cannot be expected. FIG. 8 shows a case where the tip end portion 81 of the blade 80 is bent downward to form a dihedral angle.

However, generally, the blade tip vortex generated from the blade has a property of moving downward and inward by blowing down, and in the case of a rectangular blade as shown in FIG. 6, the trailing blade is above the blade tip vortex of the preceding blade. However, in the shape shown in FIG. 8 in which the tip is positively directed downward, the tip of the trailing blade enters the region of the tip vortex generated by the leading blade, and the angle of attack is locally increased. Change, which may cause vibrations and the like, which deteriorates aerodynamic characteristics.

Further, at the tip end portion having the dihedral angle, there is a drawback that a downward pushing force is generated and a so-called negative lift is generated, and conversely, there is a problem that a large blade rotating torque is required. ..

The present invention has been made in view of the above circumstances, and an object thereof is to increase the lift of the blade with a simple structure, reduce the blade rotation torque, and improve the fuel consumption. It aims to provide a helicopter that can.

[0011]

In order to achieve the above object, the present invention is designed so that the blade tip portion of the main rotor is bent upward to form a dihedral angle and a lift force is generated at this blade tip portion. Is characterized by.

[0012]

When the tip of the blade is provided with a dihedral angle as in the present invention, the tip vortex generated at the tip of the blade is slightly raised during hovering as compared with the case of a normal rectangular blade. And the tip vortex will hit the following blade. In this case, the vortex itself flows tangentially from the tip of the blade, but this tip vortex is
(B), the flow is in the tangential direction of the swirling circle, and since the blade is advancing, it looks like a spiral vortex is coming in from the following blade. Such a spiral vortex induces an air flow from diagonally lower front to diagonally upper rear. As a result, lift is generated at the tip of the blade having the dihedral angle. That is, the winglet effect can generate a lift that leans forward, so that the blade rotation torque can be reduced and fuel consumption can be improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in FIGS. In the helicopter shown in FIG. 5, 1 is a fuselage, 2 is a main rotor, 3 is a main shaft, 4 ... Blades of the main rotor 2, and 5 is a tail auxiliary rotor.

Each of the blades 4 ... Has a blade shape whose cross-sectional shape is larger than the length of the lower surface in the upper surface like the NACA type shown in FIG. Also, each blade 4
Has a pitch angle α such that the front edge of the blade faces upward with respect to the horizontal plane.

The blades 4 are provided with a twist so that the pitch angle on the blade tip side is smaller than the pitch angle on the turning center side (root side), whereby the blades 4 ... The distribution of lift generated is made relatively small on the blade tip side where the velocity is high. In addition,
The pitch angle α on the blade tip side never becomes negative.

In such a blade 4, a predetermined length portion of the blade tip is bent upward at a predetermined angle, and a so-called dihedral angle θ is attached. In the case of the present embodiment, the tip bending portion 6 has a bending line 7 in which the blade 4 ...
It is arranged along the tangential direction of the turning circle. The operation of the helicopter having such a configuration will be described.

When the main rotor 2 turns, each blade 4
Turns around the main shaft 3. When the blade 4 turns,
A lift is generated in each blade 4, and when this lift overcomes the weight of the body 1, the body 1 rises.

By the way, when the helicopter is hovering, since the machine body does not move, each blade 4 turns on the same turning plane, and therefore the succeeding blade 4 turns along the passage of the preceding blade 4. And
At the blade tip of each blade 4, a blade tip vortex Γ is generated, and this blade tip vortex Γ is a vortex flow in a clockwise direction as shown in FIG. ..

Such a clockwise tip vortex Γ hits the bent tip bending portion 6 of the following blade 4,
In addition, the flow f is directed from diagonally lower front to diagonally upper rear. This flow f produces lift as shown in FIG. That is, a tip end vortex generated at the tip of the leading blade 4 induces a flow f directed obliquely downward from the front to obliquely upward.
This induced flow strikes the lower surface of the trailing edge bent portion 6 of the blade 4 from diagonally forward to diagonally upward and backward. Therefore, a resistance M along the direction of the flow f and a lift U in a direction orthogonal to the resistance M are generated in the tip bending portion 6. Since these lift forces U are tilted forward, a resultant force F of the resistance M and the lift force U is produced. Since this resultant force F is inclined forward, a forward force, that is, a thrust force T is produced.

In other words, the backward-floating upward flow f induced by the tip vortex Γ generated by the preceding blade 4 is
Lifting force U and thrust force T are generated with respect to the tip bending portion 6 of the blade 4 that follows, and the torque Q can be reduced.

Therefore, according to such a structure, the torque can be reduced without reducing the blade area,
In addition, the lift force and the thrust force can be compensated by the tip bent portion 6 without increasing the pitch angle α, and thus without increasing the blade resistance. From this, the torque for driving the main rotor 2 can be reduced,
The rotor efficiency is improved and fuel consumption can be saved.

In the above embodiment, the bending line 7 of the tip bending portion 6 is arranged along the tangential direction of the turning circle of the blade 4, but the bending line may be inclined with respect to the tangential direction. The tip bending portion 6 is twisted and rises up. By doing so, the lift force and the thrust force can be changed according to the twisting direction and the twisting amount of the tip bending portion 6.

[0023]

As described above, according to the present invention, the blade tip vortex generated by the preceding blade induces an air flow to generate a lift force at the blade tip portion having a dihedral angle formed on the following blade. That is, the lift force can be generated by the winglet effect, so that the blade rotating torque can be reduced and the fuel consumption can be improved.

[Brief description of drawings]

FIG. 1 shows a blade of one embodiment of the present invention,
(A) figure is a top view, (b) figure is a rear view.

FIG. 2 is a cross-sectional view of the blade of the same embodiment.

FIG. 3 is a diagram showing a flow of a blade tip vortex of the blade of the embodiment.

FIG. 4 is a vector diagram for explaining the operation of the blade of the same embodiment.

FIG. 5 is a side view of the entire helicopter of the same embodiment.

FIG. 6 shows a conventional rectangular blade, in which (a) is a plan view and (b) is a rear view.

FIG. 7 is a view showing a conventional T-shaped blade, in which (a) is a plan view and (b) is a rear view.

FIG. 8 shows a conventional dihedral angled blade, (a)
The figure is a plan view and the figure (b) is a rear view.

[Explanation of symbols]

1 ... Airframe, 2 ... Main rotor, 3 ... Main shaft, 4 ... Blade, 5
... Auxiliary rotor, 6 ... Tip bending part.

Claims (1)

[Claims] 1. A helicopter, characterized in that a tip of a blade of a main rotor is bent upward to form a dihedral angle.