WO2018045575A1

WO2018045575A1 - Propeller assembly, power system, and aerial vehicle

Info

Publication number: WO2018045575A1
Application number: PCT/CN2016/098612
Authority: WO
Inventors: 王佳迪; 张永生; 梁贵彬; 陈星元
Original assignee: 深圳市大疆创新科技有限公司
Priority date: 2016-09-09
Filing date: 2016-09-09
Publication date: 2018-03-15
Also published as: CN108463406A

Abstract

A propeller assembly, a power system, and an aerial vehicle. The propeller assembly (13) comprises first propellers (131) and second propellers (132) that are disposed at intervals. Each first propeller (131) comprises a first propeller hub (1311) and at least one first blade (1312) connected to the first propeller hub (1311). Each second propeller (132) comprises a second propeller hub (1321) and at least one second blade (1312) connected to the second propeller hub (1321). During the rotation of the propeller assembly (13), acceleration air flows generated duration the rotation of the first propellers (131) point to the second propellers (132) from the first propellers (131) and act on the second propellers (132), so that the radial attack angle line types of the second blades (1322) are different from those of the first blades (1312). In this way, the radial attack angle line types of the blades on different layers are set to be different from each other, and accordingly the impacts of difference between air flow speeds among the blades on different layers to the working effects of the propellers can be effectively avoided.

Description

Propeller assembly, power system and aircraft

[Technical Field]

Embodiments of the present invention relate to the field of power, and more particularly to a propeller assembly, a power system, and an aircraft.

【Background technique】

A propeller is a device that relies on a blade to rotate in a transmission medium such as air or water to convert the engine's rotational power into thrust or tension. It is widely used in the power system of aircraft, submarines and other devices. Taking a multi-rotor aircraft as an example, in order to obtain greater lift with the same projection size, a coaxial twin-blade propeller design is generally used, that is, two layers of propellers are arranged at upper and lower intervals along the same axial direction.

However, when a coaxial double paddle is used, the airflow generated by the upper blade during the rotation will enter the lower blade, resulting in the flow velocity of the lower blade being much higher than the flow velocity of the upper blade. In the existing coaxial twin-blade propeller design, the upper blade and the lower blade generally adopt the same angle of attack design, and the above airflow velocity difference may cause the upper blade and the lower blade to fail to achieve the expected working effect. For example, the paddle efficiency of the lower blade is greatly lost due to the difference in the air flow rate described above.

[Summary of the Invention]

Embodiments of the present invention provide a propeller assembly, a power system, and an aircraft to solve the effect on the working effect of the propeller due to the difference in airflow velocity between the blades of different layers.

In order to solve the above technical problem, a technical solution adopted by the embodiment of the present invention is to provide a propeller assembly including a first propeller and a second propeller disposed at intervals, the first propeller including the first hub and the first hub At least one first blade, the second propeller includes a second hub and at least one second blade connecting the second hub, during the rotation of the propeller assembly, the accelerated airflow generated by the first propeller rotation process is from the first The propeller points and acts on the second propeller, and the radial angle of attack of the second blade is different from the radial angle of attack of the first blade.

Wherein, the radial angle of attack adopted by the second blade makes the paddle efficiency of the second propeller more efficient than that of the second blade when the second blade adopts the radial angle of attack of the first blade .

Wherein, the paddle efficiency of the second propeller depends on the magnitude of the pulling force generated when the second propeller rotates at a specific rotational speed.

Wherein, the rotating shaft of the first propeller is coaxially arranged with the rotating shaft of the second propeller, and the first screw is At least a portion of the accelerated airflow generated by the spinner rotation process enters the second propeller from the first propeller.

Wherein, at the same radial position of the common axis of the distance between the first propeller and the second propeller, the angle of attack of the second blade is greater than the angle of attack of the first blade.

Wherein, in the case where the first blade and the second blade are equally or equally scaled to be equal in length and the outer ends of the first blade and the second blade are equidistant from the common axis, the radius is first At a position of 25.9% of the distance between the outer end of the blade and the second blade and the common shaft, the difference between the angle of attack of the second blade and the angle of attack of the first blade is 10.4 ± 0.5 degrees.

Wherein, in the case where the first blade and the second blade are equally or equally scaled to be equal in length and the outer ends of the first blade and the second blade are equidistant from the common axis, the radius is first At a position of 44.4% of the distance between the outer end of the blade and the second blade and the common shaft, the difference between the angle of attack of the second blade and the angle of attack of the first blade is 13.9 ± 0.5 degrees.

Wherein, in the case where the first blade and the second blade are equally or equally scaled to be equal in length and the outer ends of the first blade and the second blade are equidistant from the common axis, the radius is first At a position of 63.0% of the distance between the outer end of the blade and the second blade and the common shaft, the difference between the angle of attack of the second blade and the angle of attack of the first blade is 8.4 ± 0.5 degrees.

Wherein, in the case where the first blade and the second blade are equally or equally scaled to be equal in length and the outer ends of the first blade and the second blade are equidistant from the common axis, the radius is first At a position of 81.5% of the distance between the outer end of the blade and the second blade and the common shaft, the difference between the angle of attack of the second blade and the angle of attack of the first blade is 5.2 ± 0.5 degrees.

Wherein, in the case where the first blade and the second blade are equally or equally scaled to be equal in length and the outer ends of the first blade and the second blade are equidistant from the common axis, the radius is first At a position 100% of the distance between the outer end of the blade and the second blade and the common shaft, the difference between the angle of attack of the second blade and the angle of attack of the first blade is 6 ± 0.5 degrees.

In order to solve the above technical problem, one technical solution adopted by the embodiment of the present invention is to provide a power system including a propeller assembly and a motor assembly for driving the propeller assembly, the propeller assembly including the first propeller and the interval a second propeller, the first propeller includes at least one first blade, and the second propeller includes at least one second blade. During the rotation of the propeller assembly, the accelerated airflow generated by the first propeller rotation process is directed from the first propeller and acts In the second propeller, the radial angle of attack of the second blade is different from the radial angle of attack of the first blade.

Wherein the rotating shaft of the first propeller is disposed coaxially with the rotating shaft of the second propeller, and at least a portion of the accelerating airflow generated by the first propeller rotating process enters the second propeller from the first propeller.

Wherein the motor assembly includes a first motor for driving the first propeller and a second motor for driving the second propeller.

In order to solve the above technical problem, one technical solution adopted by the embodiment of the present invention is to provide an aircraft including a power system and an arm supporting the power system, the power system including a propeller assembly and a motor assembly for driving the propeller assembly. The propeller assembly includes a first snail spaced apart a propeller and a second propeller, the first propeller including at least one first blade, and the second propeller including at least one second blade, the acceleration airflow generated by the first propeller rotation process from the first during the rotation of the propeller assembly The propeller points and acts on the second propeller, and the radial angle of attack of the second blade is different from the radial angle of attack of the first blade.

Wherein, in the case where the first blade and the second blade are equally or equally scaled to be equal in length and the outer ends of the first blade and the second blade are equidistant from the common axis, the radius is first At an angle of 100% of the distance between the outer end of the blade and the second blade and the common shaft, the angle of attack of the second blade and the angle of attack of the first blade The difference between the two is 6 ± 0.5 degrees.

The beneficial effects of the embodiments of the present invention are: in the propeller assembly, the power system and the aircraft provided by the embodiments of the present invention, the radial angle of attack of the different layers of blades is set to be different from each other, and the different layers of blades can be effectively avoided. The effect of the difference in airflow velocity between the working effects of the propeller.

[Description of the Drawings]

1 is a partial perspective view of an aircraft using a propeller assembly in accordance with an embodiment of the present invention;

Figure 2 is a side elevational view of the propeller assembly of Figure 1;

3 is a schematic diagram showing a radial angle of attack example of a two-layer blade of a propeller assembly in accordance with an embodiment of the present invention;

4 is a top plan view of a two-layer paddle in accordance with another embodiment of the present invention;

Figure 5 is a schematic cross-sectional view of the two-layer paddle of the propeller assembly taken along line A-A of Figure 4;

Figure 6 is a schematic cross-sectional view of the two-layer paddle of the propeller assembly taken along line B-B of Figure 4;

Figure 7 is a schematic cross-sectional view of the two-layer paddle of the propeller assembly taken along line C-C of Figure 4;

Figure 8 is a schematic cross-sectional view of the two-layer paddle of the propeller assembly taken along line D-D of Figure 4;

Figure 9 is a schematic cross-sectional view of two layers of blades of the propeller assembly taken along line E-E of Figure 4;

【detailed description】

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Referring to FIG. 1, FIG. 1 is a partial perspective view of an aircraft using a propeller assembly in accordance with an embodiment of the present invention. The aircraft of the present embodiment includes an arm 11, a motor assembly 12 supported on the arm 11, and a propeller assembly 13 driven by the motor assembly 12. Among them, the propeller assembly 13 includes a first propeller 131 and a second propeller 132 that are spaced apart. The first propeller 131 includes a first hub 1311 and at least one first blade 1312 coupled to the first hub 1311. The second propeller 132 includes a second hub 1321 and at least a second connected to the second hub 1321. Blade 1322. In the present embodiment, the number of the first paddle 1312 and the second paddle 1322 is two. In other embodiments, the number of the two can be rooted. Arbitrarily set according to actual needs. Further, in the present embodiment, the rotation axes of the first propeller 131 and the second propeller 132 are coaxially disposed, and the motor assembly 12 includes two

motors

121, 122 that drive the first propeller 131 and the second propeller 132, respectively. However, in other embodiments, the axes of rotation of the first propeller 131 and the second propeller 132 may be arranged in parallel, or the first propeller 131 and the second propeller 132 may also be driven by the same motor.

In the present embodiment, the propeller assembly 13 and the motor assembly 12 constitute the power system of the aircraft and provide the aircraft with the power required to fly through the rotation of the first propeller 131 and the second propeller 132.

Please refer to FIG. 2. FIG. 2 is a side view of the propeller assembly shown in FIG. 1. During the rotation of the propeller assembly 13, the accelerated airflow generated by the rotation of the first propeller 131 is directed from the first propeller 131 and acts on the second propeller 132. Specifically, as shown in FIG. 2, at least a portion of the accelerated airflow generated by the rotation of the first propeller 131 enters the second propeller 132 from the first propeller 131 in the direction indicated by the arrow, resulting in the first propeller 131 and the second propeller 132. The airflow at the location has a certain flow rate difference.

In the present embodiment, in order to overcome the influence of the above-described flow velocity difference on the working effects of the first propeller 131 and the second propeller 132, the radial angle of attack of the second blade 1322 of the second propeller 132 is designed to be different first. The radial angle of attack of the first paddle 1321 of the propeller 131. Among them, the radial angle of attack line refers to the curve of the angle of attack of the blade along the radial direction of the propeller.

Please refer to FIG. 3, which is a schematic diagram of a radial angle of attack example for a two-layer blade of a propeller assembly in accordance with an embodiment of the present invention. As described above, since the flow velocity of the second propeller 132 is much higher than the flow velocity of the first propeller 131, the paddle efficiency of the second propeller 132 is lowered. In the present embodiment, the paddle efficiency of the second propeller 132 depends on the amount of tension generated by the second propeller 132 at a particular rotational speed. In short, the greater the pulling force produced at a particular speed, the higher the efficiency of the paddle.

To this end, in the present embodiment, the first blade 1312 of the first propeller 131 selects the radial angle of attack line shown by the curve 10, and the second blade 1322 of the second propeller 132 selects the radial direction shown by the curve 20. Angle of attack line type. In the two radial angle of attack types shown in FIG. 3, the angle of attack of the second blade 1322 at the same radial position of the common axis (origin) of the distance between the first propeller 131 and the second propeller 132 An angle of attack greater than the first blade 1312.

With the above design, in the case where the airflow velocity difference exists, the second propeller 1322 can adopt the radial angle of attack type shown by the curve 20, and the second propeller 132 has the paddle efficiency higher than that of the second blade 1322. The pitch of the second helical propeller 132 of the radial angle of attack shown by curve 10 is more efficient (eg, generated) The pulling force is greater), thereby overcoming the effect of the above-described airflow velocity difference on the paddle efficiency in the case where the first blade 1312 and the second blade 1322 are of the same radial angle of attack.

The above embodiment only illustrates the specific example of the first blade 1312 and the second blade 1322 by taking the paddle efficiency as an example. Of course, after reading the present invention, those skilled in the art can fully think of the first blade in other ways. The radial angle of attack of the 1312 and the second blade 1322 are set to be different from each other to achieve the desired working effect. In addition, it should be noted that although the above embodiment has been described by taking only two-layer paddles as an example, the embodiments of the present invention are applicable to other multi-layer paddle designs such as three-layer paddles and four-layer paddles.

Referring to Figures 4-9, specific parameters of the first paddle 1312 and the second paddle 1322 will be described below in conjunction with specific examples.

4 is a top plan view of a two-layer paddle according to another embodiment of the present invention, and FIGS. 5-9 are first taken at different radial positions of the first paddle 1312 and the second paddle 1322 shown in FIG. A schematic cross-sectional view of the paddle 1312 and the second paddle 1322, in turn, compares the difference between the angle of attack of the first paddle 1312 and the second paddle 1322. In the present embodiment, as shown in FIG. 4, the first paddle 1312 and the second paddle 1322 are equally long and the outer ends of the first paddle 1312 and the second paddle 1322 are equidistant from the common axis, The specific distance is shown as L in FIG. Of course, in other embodiments, any of the first paddle 1312 and the second paddle 1322 can also be scaled in a practical application such that the actual length of the first paddle 1312 and the second paddle 1322 Inconsistent. However, when the first paddle 1312 and the second paddle 1322 are equally scaled to be equal to each other, and the outer ends of the two are equidistant from the common axis, the first paddle 1312 and the second paddle 1322 The angle of attack between the two still meets the following range of numbers.

As shown in FIGS. 4 and 5, at a position where the radius is 25.9% of the distance L between the outer end portion of the first paddle 1312 and the second paddle 1322 and the common axis, that is, 25.9% L as shown in FIG. At the position, the angle of attack a12 of the second blade 1322 is 28.7 degrees, and the angle of attack a11 of the first blade 1312 is 18.3 degrees, and the difference between the two is 10.4, and further consideration is made for manufacturing and equipment tolerances. The difference between them is preferably 10.4 ± 0.5 degrees.

As shown in FIGS. 4 and 6, at a position where the radius is 44.4% of the distance L between the outer end portion of the first paddle 1312 and the second paddle 1322 and the common axis, that is, the position of 44.4% shown in FIG. Wherein, the angle of attack a22 of the second blade 1322 is 26.9 degrees, and the angle of attack a21 of the first blade 1312 is 13.0 degrees, the difference between the two is 13.9, and further consideration is made between manufacturing and equipment tolerances. The difference is preferably 13.9 ± 0.5 degrees.

As shown in FIGS. 4 and 7, at a position where the radius is 63.0% of the distance L between the outer end portion of the first paddle 1312 and the second paddle 1322 and the common axis, that is, 63.0% L as shown in FIG. Position, second paddle The angle of attack a32 of the 1322 is 19.2 degrees, the angle of attack a31 of the first blade 1312 is 10.8 degrees, and the difference between the two is 8.4, and further considering the manufacturing and equipment tolerances, the difference between the two is preferably 8.4. ±0.5 degrees.

As shown in FIGS. 4 and 8, at a position where the radius is 81.5% of the distance L between the outer end portion of the first paddle 1312 and the second paddle 1322 and the common axis, that is, 81.5% L as shown in FIG. At the position, the angle of attack a42 of the second blade 1322 is 14.0 degrees, the angle of attack a41 of the first blade 1312 is 8.8 degrees, and the difference between the two is 5.2, and further consideration is made for manufacturing and equipment tolerances. The difference between the two is preferably 5.2 ± 0.5 degrees.

As shown in FIGS. 4 and 9, at a position where the radius is 100% of the distance L between the outer end portion of the first paddle 1312 and the second paddle 1322 and the common axis, that is, at the L position shown in FIG. The angle of attack a52 of the second blade 1322 is 13.0 degrees, the angle of attack a51 of the first blade 1312 is 7.0 degrees, and the difference between the two is 6 degrees, and further consideration is made between manufacturing and equipment tolerances. The difference is preferably 6 ± 0.5 degrees.

In summary, those skilled in the art can easily understand that in the propeller assembly, the power system and the aircraft provided by the embodiments of the present invention, the radial angle of attack of different layer blades is set to be different from each other, and different layers can be effectively avoided. The effect of the difference in airflow velocity between the blades on the working effect of the propeller. Further, the specific angle of attack design effectively avoids the influence of the difference in airflow velocity on the propeller.

The above is only the embodiment of the present invention, and is not intended to limit the scope of the invention, and the equivalent structure or equivalent process transformations made by the description of the invention and the drawings are directly or indirectly applied to other related technologies. The fields are all included in the scope of patent protection of the present invention.

Claims

A propeller assembly, characterized in that the propeller assembly includes spaced apart first and second propellers, the first propeller including at least one first blade, and the second propeller including at least one second blade During the rotation of the propeller assembly, an accelerated airflow generated by the first propeller rotation process is directed from the first propeller and acts on the second propeller, and the second blade has a radial angle of attack The line type is different from the radial angle of attack of the first blade.
The propeller assembly of claim 1 wherein said second blade employs a radial angle of attack such that said second propeller has a paddle efficiency as compared to said second blade The second propeller has a higher paddle efficiency when the first blade has a radial angle of attack.
The propeller assembly of claim 1 wherein the paddle efficiency of the second propeller is dependent upon the amount of tension generated by the second propeller when rotated at a particular rotational speed.
The propeller assembly according to claim 1, wherein a rotation axis of the first propeller is disposed coaxially with a rotation axis of the second propeller, and at least an accelerated air flow generated by the first propeller rotation process Partially entering the second propeller from the first propeller.
The propeller assembly according to claim 4, wherein at an same radial position of a common axis of both the distance between the first propeller and the second propeller, an angle of attack of the second blade is greater than The angle of attack of the first blade is described.
The propeller assembly of claim 4 wherein said first blade and said second blade are equally or equally scaled to be equal in length and said first blade and said second paddle Where the outer end of the leaf is equidistant from the common axis, the radius is 25.9% of the distance between the outer end of the first blade and the second blade and the common axis The difference between the angle of attack of the second blade and the angle of attack of the first blade is 10.4 ± 0.5 degrees.
The propeller assembly of claim 4 wherein said first blade and said second blade are equally or equally scaled to be equal in length and said first blade and said second paddle Where the outer end of the leaf is equidistant from the common axis, the radius is 44.4% of the distance between the outer end of the first blade and the second blade and the common axis The difference between the angle of attack of the second blade and the angle of attack of the first blade is 13.9 ± 0.5 degrees.
The propeller assembly of claim 4 wherein said first blade and said second blade are equally or equally scaled to be equal in length and said first blade and said second paddle Where the outer end of the leaf is equidistant from the common axis, the radius is outside the first blade and the second blade At a position of 63.0% of the spacing between the end and the common axis, the difference between the angle of attack of the second blade and the angle of attack of the first blade is 8.4 ± 0.5 degrees.
The propeller assembly of claim 4 wherein said first blade and said second blade are equally or equally scaled to be equal in length and said first blade and said second paddle Where the outer end of the leaf is equidistant from the common axis, the radius is 81.5% of the distance between the outer end of the first blade and the second blade and the common axis The difference between the angle of attack of the second blade and the angle of attack of the first blade is 5.2 ± 0.5 degrees.
The propeller assembly of claim 4 wherein said first blade and said second blade are equally or equally scaled to be equal in length and said first blade and said second paddle Where the outer end of the leaf is equidistant from the common axis, at a radius of 100% of the distance between the outer end of the first blade and the second blade and the common axis The difference between the angle of attack of the second blade and the angle of attack of the first blade is 6 ± 0.5 degrees.
A power system, characterized in that the power system includes a propeller assembly and a motor assembly for driving the propeller assembly, the propeller assembly including a first propeller and a second propeller disposed at intervals, the first propeller including At least one first blade, the second propeller including at least one second blade, the accelerated airflow generated by the first propeller rotation process is directed from the first propeller during rotation of the propeller assembly Acting on the second propeller, the radial angle of attack of the second blade is different from the radial angle of attack of the first blade.
The power system of claim 11 wherein said second blade has a radial angle of attack such that the paddle efficiency of said second propeller is the same as said second blade The second propeller has a higher paddle efficiency when the first blade has a radial angle of attack.
The power system of claim 11 wherein the paddle efficiency of said second propeller is dependent upon the amount of tension generated when said second propeller is rotated at a particular rotational speed.
The power system according to claim 11, wherein a rotation axis of said first propeller is disposed coaxially with a rotation axis of said second propeller, and at least an acceleration air flow generated by said first propeller rotation process Partially entering the second propeller from the first propeller.
The power system according to claim 14, wherein at the same radial position of the common axis of both the distance between the first propeller and the second propeller, the angle of attack of the second blade is greater than The angle of attack of the first blade is described.
The power system of claim 14 wherein said first blade and said second blade are equally or equally scaled to be equal length and said first blade and said second paddle Outer end of the leaf In the case of being equidistantly disposed from the common axis, at a position where the radius is 25.9% of the distance between the outer end of the first blade and the second blade and the common axis, the first The difference between the angle of attack of the two blades and the angle of attack of the first blade is 10.4 ± 0.5 degrees.
The power system of claim 14 wherein said first blade and said second blade are equally or equally scaled to be equal length and said first blade and said second paddle Where the outer end of the leaf is equidistant from the common axis, the radius is 44.4% of the distance between the outer end of the first blade and the second blade and the common axis The difference between the angle of attack of the second blade and the angle of attack of the first blade is 13.9 ± 0.5 degrees.
The power system of claim 14 wherein said first blade and said second blade are equally or equally scaled to be equal length and said first blade and said second paddle Where the outer end of the leaf is equidistant from the common axis, the radius is 63.0% of the distance between the outer end of the first blade and the second blade and the common axis The difference between the angle of attack of the second blade and the angle of attack of the first blade is 8.4 ± 0.5 degrees.
The power system of claim 14 wherein said first blade and said second blade are equally or equally scaled to be equal length and said first blade and said second paddle Where the outer end of the leaf is equidistant from the common axis, the radius is 81.5% of the distance between the outer end of the first blade and the second blade and the common axis The difference between the angle of attack of the second blade and the angle of attack of the first blade is 5.2 ± 0.5 degrees.
The power system of claim 14 wherein said first blade and said second blade are equally or equally scaled to be equal length and said first blade and said second paddle Where the outer end of the leaf is equidistant from the common axis, at a radius of 100% of the distance between the outer end of the first blade and the second blade and the common axis The difference between the angle of attack of the second blade and the angle of attack of the first blade is 6 ± 0.5 degrees.
The power system of claim 11 wherein said motor assembly includes a first motor for driving said first propeller and a second motor for driving said second propeller.
An aircraft, characterized in that the aircraft includes a power system and a boom supporting the power system, the power system including a propeller assembly and a motor assembly for driving the propeller assembly, the propeller assembly including an interval setting a first propeller and a second propeller, the first propeller including at least one first blade, the second propeller including at least one second blade, during the rotation of the propeller assembly, via the first An accelerated airflow generated by the propeller rotation process is directed from the first propeller and acts on the second propeller, and the second blade has a different radial angle of attack The radial angle of attack of the first blade.
The aircraft according to claim 22, wherein said second blade adopts a radial angle of attack such that the paddle efficiency of said second propeller is compared to said second blade The second propeller has a higher paddle efficiency when the blade has a radial angle of attack.
The aircraft of claim 22 wherein the paddle efficiency of said second propeller is dependent upon the amount of tension generated by said second propeller as it rotates at a particular rotational speed.
The aircraft according to claim 22, wherein a rotational axis of said first propeller is disposed coaxially with a rotational axis of said second propeller, and at least a portion of said accelerated airflow generated by said first propeller rotational process From the first propeller enters the second propeller.
The aircraft according to claim 25, wherein an angle of attack of said second blade is greater than said angle at a same radial position of a common axis of both said first propeller and said second propeller The angle of attack of the first blade.
The aircraft according to claim 25, wherein said first blade and said second blade are equally or equally scaled to be equal in length and said first blade and said second blade Where the outer end portion is equidistant from the common axis, at a position where the radius is 25.9% of the distance between the outer end of the first blade and the second blade and the common axis The difference between the angle of attack of the second blade and the angle of attack of the first blade is 10.4 ± 0.5 degrees.
The aircraft according to claim 25, wherein said first blade and said second blade are equally or equally scaled to be equal in length and said first blade and said second blade Where the outer end portion is equidistant from the common axis, at a position where the radius is 44.4% of the distance between the outer end of the first blade and the second blade and the common axis The difference between the angle of attack of the second blade and the angle of attack of the first blade is 13.9 ± 0.5 degrees.
The aircraft according to claim 25, wherein said first blade and said second blade are equally or equally scaled to be equal in length and said first blade and said second blade Where the outer end portion is equidistant from the common axis, at a position where the radius is 63.0% of the distance between the outer end portion of the first blade and the second blade and the common axis The difference between the angle of attack of the second blade and the angle of attack of the first blade is 8.4 ± 0.5 degrees.
The aircraft according to claim 25, wherein said first blade and said second blade are equally or equally scaled to be equal in length and said first blade and said second blade Where the outer end portion is equidistant from the common axis, at a position where the radius is 81.5% of the distance between the outer end of the first blade and the second blade and the common axis The angle of attack of the second blade and the first paddle The difference between the angles of attack of the leaves is 5.2 ± 0.5 degrees.
The aircraft according to claim 25, wherein said first blade and said second blade are equally or equally scaled to be equal in length and said first blade and said second blade Where the outer end portion is equidistant from the common axis, at a position where the radius is 100% of the distance between the outer end portion of the first blade and the second blade and the common axis The difference between the angle of attack of the second blade and the angle of attack of the first blade is 6 ± 0.5 degrees.
The aircraft of claim 22 wherein said motor assembly includes a first motor for driving said first propeller and a second motor for driving said second propeller.