JP3533441B2 - Helicopter blade with upside down angle - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blade for a helicopter that levitates a helicopter in the air and generates a propulsive force required for flight, and in particular, by rotating the blade, it moves one blade before a blade. In order to reduce the influence of disturbance (wing tip vortex) generated by a provided blade (hereinafter referred to as a leading blade) on a blade (hereinafter referred to as a trailing blade) including a blade rotating behind the leading blade, A shape in which the side surface shape of the blade tip portion of the blade in the width direction is tilted upward and downward, that is, with a so-called upside-down anti-angle which is formed by giving the blade blade tip a dihedral angle. Helicopter blades.

[0002]

2. Description of the Related Art In a helicopter, as shown in FIG. 6, a blade 02 connected to the apex of a rotary shaft projecting vertically upward from a body 03 top of a helicopter 01 is transmitted from an engine installed in the body 03. The helicopter 01 is levitated in the air by being rotated by the driving force, and at the same time, the lift force L for generating the levitation force and thrust required for flight is generated. The conventional blade 02 that generates a lift force at the airspeed V at the time of rotation is arranged in a substantially horizontal state from the blade root connected to the rotating shaft to the blade tip when the deflection due to its own weight is not considered. Most of the so-called rectangular blades are used, which have a side surface shape and a planar shape that is substantially the same chord length from the blade root to the blade tip.

However, in recent years, helicopters have increased payload, increased flight speed, reduced vibration, reduced noise, and stall mitigation, and also reduced power required for flight and reduced weight increase. In order to improve flight performance, improvements from the aspect of planar shape have been advanced, various wing tip shapes effective in improving flight performance have been developed, performance of blade 02 has been improved, and helicopter 01 has high performance. Development aimed at improving performance is underway.

That is, in order to improve the performance of the blade 02, as shown in FIG. 7 (b), instead of the conventional rectangular blade whose plane shape shown in FIGS. 6 and 7 (a) is changed to a rectangular shape. Since the rotational speed R is increased and the pitch angle is set to be substantially the same in the blade width direction, the lift generation at the blade tip portion, which increases the lift force, is reduced to smooth the lift distribution in the blade width direction, Aerodynamic load to reduce the increase in weight due to the increase in structural strength, delay the separation of the blade tip flow that occurs with the increase of the lift distribution at the blade tip, and vibration due to the flow separation, In order to reduce noise or alleviate stall, a tapered blade tip 021 having a thin blade tip is used.

Further, the normal airspeed V is about twice as high as the maximum flight speed, and the resistance divergence due to the compressibility at high speed generated by the blade 02 advancing on the right side of the body 03 in FIG. 6 is high Mach number. In order to suppress the area, as shown in FIG. 7 (c), a plane surface such as a so-called receding blade tip blade 022 that is bent in a direction opposite to the rotation direction in which the blade tip has the maximum speed is formed. Is under development for improving the performance of the blade 02.

A blade 02 unique to the helicopter 01
The vibration of the leading edge of the leading blade 02a that interferes with (affects) the trailing blade 02b, which is caused by the rotation of the blade, and the side surface shape of the blade 02 to reduce noise. There is. In particular, helicopter 01
In order to suppress wing tip vortex interference that occurs during so-called hovering flight, where the wing tip stops at a fixed position in the air, the wing tip portion extends from the bent portion 04 to the wing tip in the spanwise direction as shown in Fig. 7 (d). Bent toward the bottom of the rotor rotation surface,
Dihedral angle tip blade 023 with so-called dihedral angle
In order to improve the performance of the blade 02 from the side surface shape, the influence of the tip vortex generated on the leading blade 02a on the trailing blade 02b is reduced.

Next, the improvement for improving the performance of the blade 02, which is made from such a side surface shape, will be described. The helicopter 01 is normally provided with a plurality of blades 02 as shown in FIG.
When the blade tip vortex TV generated from the blade tip portion of the leading blade 02a during the rotation of 1 approaches the trailing blade 02b, the induced velocity IV generated in the trailing blade 02b with a substantially uniform size in the span direction is , Due to the influence of this wing tip vortex TV,
As shown in (a), since the distribution of the induced velocity IV near the tip of the blade 02b becomes uneven, the trailing blade 02b
The angle of attack distribution in the wing span has unevenness, which increases the resistance.

The increase in resistance due to the unevenness generated in the distribution of the induced velocity IV causes the airspeed V at the blade tip of the blade 02 to be about double as compared with the forward velocity F, as described above.
Although it occurs during normal flight, in particular, when the helicopter 01 is hovering, the wing tip vortex TV from the preceding blade 02a, which is one before the trailing blade 02b, is due to the helicopter 01 stopping flight. , The blade tip vortex center CV of the blade tip vortex TV slightly moves in the direction of the rotation center below the blade 02, as shown by the dotted line in FIG. As shown in FIG. 8B, when the trailing blade 02b reaches the position where the blade tip vortex TV is generated, the trailing blade 02b stays in the vicinity of the position where the blade tip vortex TV is generated.

For this reason, the trailing blade 02b that rotates on the same locus as the leading blade 02a that generated the blade tip vortex TV.
The distance between the blade and the blade tip vortex IV is small, and the trailing blade 02b falls within the blade tip vortex influence area AV due to the blade tip vortex IV generated from the leading blade 02a. The induced velocity IV near the edge is shown in FIG.
As shown in (a), a large unevenness occurs, and a large unevenness occurs in the attack angle distribution in the blade width direction of the trailing blade 02b, which causes a large resistance in the blade 02.

Therefore, the blade 02 has a width of about 9
By using an anti-diagonal blade tip 023 with an anti-angle as shown in FIG. 9 at the blade tip at the 0% position, the blade that becomes particularly prominent when approaching the trailing blade 02b during hovering It is considered to reduce the resistance increase of the blade 2 by separating the end vortex TV from the rotating surface of the trailing blade 02b as much as possible to reduce the unevenness of the induced velocity IV excited by the tip vortex TV.

That is, the blade tip vortex TV is generated if the blade 02 wing tip is formed into the dihedral angle tip 023 so that the generation point of the wing tip vortex TV is shifted downward away from the rotation surface of the blade 02. When the trailing blade 02b, which rotates behind the leading blade 02a thus approached, approaches the trailing blade 02b and the blade as shown in FIG. 9, since the blade tip vortex TV is slightly moving toward the rotor rotation center. The distance from the end vortex TV is widened, and the trailing blade 02 from the wing tip vortex center CV, which has a large influence
b can be separated, and the influence of the tip vortex TV can be reduced.

However, the strength of the blade tip vortex TV generated from the blade tip of the blade 02 is high, and the blade tip vortex influence range A
V becomes large as shown in the figure, and if only such a gentle dihedral is applied, the dihedral tip blade 02
Since all of 3 fall within the blade tip vortex influence range AV, the influence from the blade tip vortex TV cannot be alleviated so much, and the blade tip vortex T from the leading blade 02a of the trailing blade 02b can be reduced.
In order to reduce the influence of V, as is apparent from the figure, the dihedral angle provided at the blade tip is set to be much larger than the dihedral angle of the dihedral dihedral tip blade 02 shown in the figure. It is necessary to set the dihedral angle so that the blade 02 is out of the blade tip vortex influence range AV so as not to be influenced by the blade tip vortex TV.

For this reason, the blade tip vortex TV is set to the blade 02.
As shown in FIG. 10, the blade 0
It is also conceivable that the blade tip portion of No. 2 at a position of about 97 to 98% in the spanwise direction is made into a dihedral angle blade tip 023 in which the dihedral angle is increased from the bent portion 04. However, if the dihedral angle of the blade tip portion is increased to further separate the blade tip vortex TV from the blade rotation surface, the curvature in the radial direction at the bending point 04, which is the starting point of the dihedral angle, increases, so that the blade 02 surface The flow of air along the curve cannot follow this curvature, and as shown in FIG. 10, separation occurs at this bending point 04, and a bending vortex C is generated from the bending portion 04, causing the blade tip vortex TV to move. The effect obtained by separating from the surface of rotation is
Due to the interference with the blade 02 by the bending vortex C, there is a problem that it disappears.

That is, this bending vortex C also moves toward the center of rotation below the blade 02, as shown by the dotted line in the figure, in the same way as the tip vortex TV, and the strength of the bending vortex C, in other words, the bending vortex. The influence area AC also has the same size as the blade tip vortex influence area AV and is generated from the blade root side from the position where the blade tip vortex TV is generated. Therefore, the blade 09 has a curved vortex C over a long range in the blade width direction. As a result, the trailing blade 02 is greatly affected by the resistance. Therefore, even if the trailing blade 02b is rotated outside the blade tip vortex influence area AV and is not affected by the blade tip vortex TV, the trailing blade 02b is caused by the bending vortex C.
It becomes difficult to suppress the increase in resistance.

Further, bending at such a large angle to form the bending point 04 at a large angle on the blade 02 is not structurally good such as a large stress concentration occurring at the bending point 04, and further described below. There will be a problem that the bending moment of the blade 02 becomes large due to the centrifugal force generated at the dihedral tip 023, or the possibility that the blade 02 will come into contact with the body 03 of the helicopter 01 during rotation will become large. .

Therefore, as shown in FIG. 11, the blade 0
By bending the blade tip of No. 2 in two times, the bending angle of one time is made small, and the blade 02 blade tip is bent downward so as to surround the blade tip vortex influence range AV. The blade tip vortex T is formed by forming the anti-diagonal blade tip 023 and without generating the bending vortex C from the bending portion 4 or by preventing the blade 02 from entering the bending vortex influence area AV.
It is also possible to remove the influence of V or the bending vortex C.

That is, of the dihedral angles provided at the blade tips, the dihedral angle provided at the blade root side is a gentle dihedral angle of about 10 ° in which no bending vortex C is generated as shown in FIG. At the same time, the large dihedral angle provided on the wing tip side is provided closer to the wing tip and is provided below, and a large dihedral angle of about 50 ° from this bent portion 04 is provided on the wing tip side. By the dihedral effect of the dihedral blade 022 having the dihedral angle, the bent portion 04 and the blade tip are positioned so that the blade 02 is located largely downward, and the blade tip is moved to the blade tip vortex influence range AV. It is also conceivable to suppress the influence of the blade tip vortex TV or the like on the blade tip by making it deviate from the bending vortex influence range AC.

In this way, the resistance increase of the blade tip portion of the blade 02 due to the blade tip vortex TV and the bending vortex C can be suppressed, but the dihedral angle is all formed below the rotating surface of the blade 02. In addition, a problem occurs due to the blade 02 being largely separated from the rotating surface. That is, in such an arrangement in which the dihedral angle is divided into two parts, the amount of dip from the rotating surface of the dihedral angle blade 02 becomes large, and the vertical mass balance of the blade 02 is disturbed, An excessive bending moment due to the centrifugal force is generated in the blade 02, and there is a problem that the possibility of contact with the body of the helicopter increases.

The problem of the centrifugal force CF occurs even in the case where the dihedral tip 023 is provided at the blade tip shown in FIGS. 9 and 10 as described above, but especially in the blade shown in FIG. The part of the dihedral angle blade 023 on the end side is
Since the blade 02 is located below the horizontal portion where the amount of downward movement is large, a large centrifugal force is generated below the blade 02, which causes a problem that a large bending moment is generated by the blade 02.

[0020]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems caused by the side surface of the blade, the present invention increases the resistance of the side shape of the blade tip portion due to the generation of blade tip vortices. The dihedral angle is added in two steps that are effective in suppressing the blade to increase the distance between the rotating surface of the blade and the blade tip vortex, and the blade tip is placed at a position where the influence of the blade tip vortex does not affect the blade. By placing the dihedral angle so that it is arranged, the centrifugal force generated below the blade by the mass balance above and below the horizontal plane of rotation of the blade is suppressed, thereby suppressing the occurrence of a bending moment generated in the blade, or the blade In order to eliminate the possibility of the vehicle colliding with the body of the helicopter, a dihedral angle is added to balance the mass above and below the horizontal plane of rotation of the blade, especially when hovering. Hakare the performance improvement of the definitive blade,
An object of the present invention is to provide a blade with a dihedral angle that can improve hovering efficiency.

[0021]

Therefore, the helicopter blade with a dihedral angle according to the present invention has the following means.

(1) A horizontal blade having a straight-line shape in which the side surface shape from the blade root portion to about 90% of the blade edge portion in the blade width direction is in a substantially horizontal state when bending is not taken into consideration is provided.

(2) The side surface shape from 90% to 94% in the blade width direction is bent upward by about 10 degrees from the straight edge of the blade in the above (1) toward the blade edge, and 1
A dihedral blade with a 0 degree dihedral was provided.

(3) The side surface shape from 94% to 98% in the span direction extends downward from the horizontal plane by about 10 to 20 degrees from the dihedral angle blade end of the above (2). A dihedral blade having a dihedral angle of about 10 to 20 degrees was provided.

(4) Further, the side surface shape from 98% in the spanwise direction to the blade tip is directed from the end portion of the dihedral blade bent downward about 10 to 20 degrees of the above (3) to the blade tip. The effective bending angle is about 30-40 degrees.
While being bent, a large dihedral angle blade provided with a large dihedral angle was bent downward about 50 to 60 degrees from the horizontal plane.

It should be noted that the connecting portion between the dihedral blade and the dihedral blade, or in other words, the uppermost position from the rotating surface of the horizontal blade, the inside of the blade is filled with a weight or the like so as to be located above the rotating surface. It is preferable to increase the mass so that the blades above and below the horizontal plane at the blade tip can be balanced in mass. Further, the connecting portion between the horizontal blade and the dihedral blade, the connecting portion between the dihedral blade and the dihedral blade, and the connecting portion between the dihedral blade and the large dihedral blade should have an acute shape. Instead, it is preferable that each has an appropriate radius of curvature.

As described above, the helicopter blade with a dihedral angle of the present invention provides the lift required for the flight of the helicopter.
The side surface shape of the blade generated by the airspeed during rotation is such that the blade tip portion of the blade formed in a straight line shape from the blade root portion to 90% of the blade width has the upper and lower sides (2) to (4) above. Angled dihedral blades, dihedral blades and large dihedral blades are made to have a wing tip side surface shape that is sequentially provided in the span direction toward the wing tip. The influence on the trailing blade of the vortex can be suppressed, and the resistance of the blade tip can be reduced.
The hovering efficiency can be improved by 5% or more as compared with the conventional blade.

That is, the helicopter blade with a dihedral angle according to the present invention has a wing tip vortex generated by the preceding blade, like the conventional blade, in which only the dihedral angle is provided at the wing tip in two steps. Can be shifted downward, and since the blade tip vortex moves in the direction of the blade rotation center after generation, the trailing blade that passes behind the blade tip vortex and the leading blade behind the blade tip vortex is generated. Can be extended to a distance that is not affected by the tip vortex, especially when hovering where the effect of the tip vortex is large, the influence of the tip vortex generated by the leading blade on the trailing blade. Can be made smaller, and the generation of unevenness of the induced velocity generated near the blade tip of the trailing blade due to the blade tip vortex generated by the leading blade is suppressed, and the blade of the trailing blade accompanying the generation of the unevenness of the induced velocity is suppressed. With end In it is possible to reduce the resistance loss generated.

Further, since the dihedral angle is divided into two and the dihedral blade and the large dihedral blade are formed, the bending angle per one time can be reduced, and the dihedral angle can be reduced. The bent portion for forming the square blade is provided at the end of the dihedral blade bent downward from the horizontal plane, and the substantial bending angle can be reduced, and the range of influence of the tip vortex Combined with the fact that the blade tip portion is formed so as to surround the, the location of the generation of the bending vortex is close to the blade tip, and is located below
The generation of the bending vortex from the bending portion, which reduces the effect of eliminating the influence of the blade tip vortex on the blade tip portion, is also suppressed, and the resistance loss generated near the blade tip can be further reduced.

Further, the helicopter blade with a dihedral angle according to the present invention is 90% of the blade tip from the blade root portion in the span direction as compared with the conventional blade in which only the dihedral angle is provided at the blade tip. From the blade end portion whose side surface shape is straight to the blade tip direction, by providing the blade with the dihedral angle bent upward, the vertical mass balance of the blade is obtained. However, as compared with a blade in which the conventional dihedral angle is provided in two steps, at least the blade can be removed. Therefore, it is possible to reduce the occurrence of an excessive bending moment due to centrifugal force in the blade, and further, It is also possible to reduce the possibility that the blade will contact the body of the helicopter.

In addition, a weight or the like is filled inside the blade such as a connecting portion between the dihedral blade and the dihedral blade,
If the mass balance of the blades above and below the horizontal surface of the blade tip can be balanced, the excessive bending moment generated in the blade due to centrifugal force can be almost eliminated, and the blade will bend due to the bending of the blade due to the generation of the bending moment. There is no possibility of contact with the body of the helicopter, and damage to the helicopter can be reliably prevented.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a helicopter blade with a dihedral angle according to the present invention will be described below with reference to the drawings. The same members as those shown in FIGS. 6 to 11 or similar members are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 is a conceptual view showing an embodiment of a helicopter blade with a dihedral angle according to the present invention. In the present embodiment, as shown in the figure, the blade 2 is once moved to the blade root side of the blade 2 at the blade root side at the 90% position in the blade width direction.
Is bent upward by 10 degrees to form a dihedral blade tip blade 21 as a dihedral blade, and then no bending vortex C is generated at the blade tip portion in the blade width direction 94% position.
A dihedral angle blade tip 22 as a dihedral blade bent by 0 to 20 degrees, and further at the blade tip portion at the blade tip direction 98% position, further from the horizontal plane 4 to 50 to 60 degrees downward The bent side surface shape of the large dihedral angle blade tip 23 as the large dihedral blade is a side surface shape having upper and dihedral angles.

By doing so, the shape of the blade tip of the blade 2 can be made to surround the blade tip vortex influencing range AV as in FIG. 11, so that it is not affected by the blade tip vortex TV. Can be Further, in order to form the great dihedral blade tip 23, the dihedral blade tip 2
The bent portion 3 formed on the blade tip side of 2 and having a large dihedral angle is moved to the blade tip side, and the dihedral angle of the bent portion 3 is 50 ° as it is from the horizontal state shown in FIG. 60 °
Although it is not provided, the horizontal plane 4 has a dihedral angle of 50 to 60 degrees, but the horizontal plane 4 to 10 degrees to 2 degrees.
Since it is provided on the wing tip side of the dihedral tip blade 22 having 0 degree, it is possible to substantially make the dihedral angle of about 30 degrees to 40 degrees. The generation of the bending vortex C can be suppressed, or a weak vortex, that is, a bending vortex influencing range AC having a small diameter can be used.
The influence on the blade tip portion of the blade 2 by the can be reduced.

Further, even if the weak vortex bending vortex C is generated above the blade tip vortex TV, the bending vortex center CC is provided with the dihedral tip blade 21. Since the blade 2 moves below the dihedral tip blade 21 or the dihedral tip blade 22 located above the horizontal plane 4 of the blade 2, the bending vortex center CC and the blade 2 are Becomes larger, and the bending vortex C
It is possible to further reduce the influence of the on the blade 2.

Further, in the present embodiment, since the dihedral blade tip shape blade 21 is provided, the mass is also arranged above the horizontal plane 4 of the blade 2, as shown in FIGS.
As shown in FIG. 1, as compared with the conventional one in which the dihedral blade tip 023 is simply provided, the mass imbalance above and below the horizontal plane 4 of the blade 2 is at least alleviated, so that the dihedral blade tip is formed. A large bending moment of the blade 02 due to the centrifugal force generated by providing only the blade 023 is relaxed, and further, the bending of the blade 2 is suppressed by the relaxation of the bending moment, so that the blade 2 and the body 3 may come into contact with each other. Can be eliminated.

Further, if the concentrated mass is applied to a portion of the blade 2 which is bent above the horizontal plane 4, particularly the uppermost portion farthest from the horizontal plane 4, the horizontal plane and the upper and lower mass of the blade 2 are perfectly balanced. Therefore, it is possible to prevent the bending moment from being generated due to the centrifugal force generated by the mass imbalance, and it is possible to make contact between the blade 2 that is bent due to the generation of the bending moment and other parts such as the body 03 of the helicopter 1. Sex can be reduced.

According to the helicopter blade with vertical dihedral of the present embodiment, the helicopter 01 blade 2 is formed into the dihedral angle blade tip 21 which is obtained by bending the blade tip of the helicopter 01 blade 2 upwards. When the helicopter 1 is in flight, particularly when the helicopter 1 is flying, the tip end is changed by changing the angle downward and bending it twice to form the dihedral angle tip blade 22 and the great dihedral angle tip blade 23. By reducing the influence of the vortex TV and the bending vortex C, the unevenness of the induced velocity IV distribution near the blade tip of the blade 2 can be reduced, and the unevenness of the elevation angle distribution near the blade tip of the blade 2 accompanying this can be reduced. The generation of the blade 2 can be suppressed, the resistance of the blade end portion of the blade 2 can be reduced, the required thrust of the helicopter 1 can be reduced, and the bending moment due to the centrifugal force and contact with other parts of the helicopter are possible. A it can be reduced.

Next, a specific example of the above-described embodiment will be described. FIG. 2 is a diagram showing a first specific example.
In this specific example, a dihedral blade tip 21 having a dihedral angle having a dihedral angle of 10 degrees is provided at 90 to 94% of the blade tip in the spanwise direction.
A dihedral angle blade blade 22 having a dihedral angle of -20 degrees at 94 to 98% of the blade tip in the spanwise direction, and 98% to the tip of the blade in the spanwise direction. The large dihedral tip blades 23 having the dihedral angle of -50 degrees are provided respectively.

FIG. 3 is a view showing a second specific example. In this specific example, 90-94% of the blade width direction blade tip portion has a dihedral angle-shaped blade tip 21 of 10 degrees. , A dihedral angle-shaped blade 22 having a blade angle of −10 degrees at 94 to 98% in the span direction, and a dihedral angle at the blade end from 98% to the tip in the span direction. The large dihedral angle blade blades 23 at -50 degrees are provided.

Further, FIG. 4 is a diagram showing a third specific example.
In this specific example, a dihedral blade with a dihedral angle of 10 ° is installed at 90% to 94% of the blade tip in the blade width direction in the blade width direction in the same manner as in the first and second embodiments. %, A dihedral angle blade blade 22 which is set to −20 degrees as in the first specific example, and a dihedral angle to the blade tip portion from 98% in the span direction to the blade tip − Greater dihedral blade width 2 at 60 degrees
3 are provided respectively. The above-mentioned position in the spanwise direction and the magnitude of the dihedral angle and the dihedral angle are not limited to those described above, but can be changed within a range of several% and several degrees. .

In the blades 2 having the above-described configurations and having the blade end side surface shapes of Examples 1 to 3, the hovering efficiency is superior to the conventional blade 02 by 5% or more as shown in FIG. You can make it Further, in any of Specific Examples 1 to 3, as is clear from FIGS. 2 to 4, since the blade tips of the blade 2 are arranged above and below the horizontal plane 4 of the blade 2 shown by the dotted line, respectively. The bending moment of the blade 2 due to the centrifugal force generated at the blade tip due to the weight imbalance between the upper and lower sides of the blade 2 can be reduced, the structural strength of the blade 2 can be reduced, the weight can be reduced, and the blade 2 associated with the bending of the blade 2 can be reduced. The possibility of collision with the body of the helicopter can be reduced.

In the case where the blade 2 at the blade tip is arranged below the horizontal plane 4 as in the first specific example shown in FIG. 2 and the third specific example shown in FIG. 4, a member of the blade 2 Since it is difficult to balance the upper and lower masses of the horizontal plane 4 only with such a structure, a position that protrudes much higher than the horizontal plane 4, such as a connecting portion between the dihedral blade tip blade 21 and the dihedral blade tip blade 22, In addition, weights etc. that make the mass even above and below the horizontal plane to balance the mass,
Preferably, it is preferably provided inside the blade 2 so as not to adversely affect the aerodynamic force acting on the surface of the blade 2.

[0044]

As described above, the helicopter blade with a dihedral angle of the present invention is 90% in the blade width direction from the blade root.
A horizontal blade having a lateral shape extending toward the wing tip of the blade in a substantially horizontal state, 90% to 94% in the width direction of the blade
% Side profile is a dihedral blade with a dihedral angle of 10 degrees from the end of the horizontal blade, 94% in the span direction
The dihedral angle blade has a dihedral angle of 10 to 20 degrees from the dihedral blade end, and the dihedral angle of 98% to the blade tip in the span direction. It consisted of a large dihedral blade with a large dihedral angle of 50-60 degrees from the end of the blade.

As a result, the location of the blade tip vortex generated by the leading blade can be shifted downward, and the distance to the trailing blade that passes behind the blade tip vortex generation point behind the leading blade can be calculated as follows. Can be extended to a distance that does not affect the influence of the blade tip vortex, especially when hovering where the influence of the blade tip vortex becomes large, it is possible to suppress the influence of the blade tip vortex generated on the leading blade and acting on the trailing blade. Therefore, it is possible to reduce the resistance loss generated near the blade tip of the trailing blade due to the influence of the blade tip vortex, and improve the hovering efficiency by 5% or more.

Further, since the dihedral angle is provided in two steps, the bending angle for one time can be reduced, and the bending portion for the large dihedral angle is substantially bent. The angle can be made small, and moreover, since it is formed so as to surround the range affected by the blade tip vortex, it is possible to reduce the effect of eliminating the effect of the blade tip on the blade tip. The generation of bending vortices is also suppressed, and the resistance loss generated near the blade tip can be further reduced.

Further, as compared with the case where only the dihedral angle is provided at the blade tip, the vertical mass of the horizontal rotating surface of the blade can be balanced, and an excessive bending moment due to centrifugal force is generated. It is possible to eliminate the possibility of contact with the helicopter such as the body.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a first embodiment of a helicopter blade with a dihedral angle according to the present invention,

FIG. 2 is a side view showing a first specific example of a helicopter blade with an upside down angle according to the embodiment shown in FIG.

FIG. 3 is a side view showing a second specific example of the helicopter blade with an upside down angle according to the embodiment shown in FIG.

FIG. 4 is a side view showing a third specific example of the helicopter blade with an upside down angle according to the embodiment shown in FIG. 1;

5 shows a first specific example of the helicopter blade with vertical dihedral shown in FIG. 2, a second specific example shown in FIG. 3, a third specific example shown in FIG. 4, and hovering efficiency of a conventional dihedral helicopter blade. Figure showing comparison,

FIG. 6 is a plan view showing a conventional helicopter,

7 is a view showing a blade of a conventional helicopter, and FIG.
FIG. 7A is a plan view of a blade having a rectangular tip.
(B) is a plan view of a blade with a tapered tip.
FIG. 7 (c) is a plan view of a blade having a swept tip, and FIG. 7 (d) is a side view of a blade having a dihedral tip.

FIG. 8 is a diagram showing the influence of a blade tip vortex on a blade tip portion, and FIG. 8 (a) is a side view showing a situation where the induced velocity distribution at the blade tip portion due to the blade tip vortex is uneven. 8 (a) is a perspective view showing the influence of a tip vortex generated on the leading blade on the trailing blade,

FIG. 9 is a side view showing a situation in which interference with a blade due to a tip vortex is reduced by providing a dihedral angle with a blade of a conventional helicopter;

FIG. 10 is a side view showing a situation in which a blade of a conventional helicopter has a large dihedral angle and the effect of reducing interference with the blade due to a tip vortex disappears;

FIG. 11 is a side view showing a situation in which a blade of a conventional helicopter is provided with a two-stage dihedral angle to reduce interference with a blade due to a tip vortex.

[Explanation of symbols]

Two blades 21 Dihedral blade tip 22 Dihedral shape blade tip blade 23 Greater dihedral angle wing tip blade 3 bends 4 (Blade) Horizontal surface 01 helicopter 02 blade 02a Leading blade 02b trailing blade 021 tapered blade tip 022 Swept-back wing tip blade 023 dihedral angle blade tip 03 torso 04 Bend R rotation speed F Forward speed V airspeed TV wing tip vortex IV induction speed CV wing tip vortex center AV wing tip vortex influence range C bending vortex CC bending vortex center AC Bending vortex influence range CF centrifugal force

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B64C 27/473

Claims (2)

(57) [Claims] 1. A helicopter blade which is provided above a helicopter and which levitates the helicopter in the air by a lift force generated at an airspeed during rotation and also generates a propulsive force required for flight, has a side shape of a wing. A straight blade is formed from the root to the blade tip, and 90% to 94% of the blade tip in the blade width direction is a dihedral blade bent upward by 10 degrees, and 94% in the blade width direction.
~ 98% of the blade tip was made an anti-diagonal blade bent downward by 10 to 20 degrees, and further, the blade tip from 98% to the blade tip in the spanwise direction was bent downward by 50 to 60 degrees. Greater dihedral blade , and the dihedral and the dihedral
Helicopter bladed vertical dihedral angle, characterized in that the bending angle of the corner is substantially 30 degrees to 40 degrees. 2. Bent above the horizontal plane of the blade
Claims characterized by filling weights inside the part
Item 2. A helicopter blade with an upside down angle according to Item 1.