Asymmetric air vane for air screw of inner and outer ring channel type air cushion ship

Abstract

The hovercraft's inner and outer ring-type air propeller uses an asymmetric air rudder. Three rudder blades are arranged side-by-side relative to the air propeller. The cross-sectional shape of the rudder blades is that of an aircraft airfoil, with the middle blade being the positive rudder blade aligned with the direction of the lateral drift force, and the two outer blades being the counter-rotating rudder blades opposite to the direction of the lateral drift force. This type of hovercraft's inner and outer ring-type air propeller uses an asymmetric air rudder, whose blades are essentially vertical airfoils. Airfoils generate lift at positive angles of attack, but generate little or no lift at negative angles of attack, having little impact on navigation. Therefore, through the shape and orientation of the three rudder blades, the lateral drift force generated by the air propeller can be counteracted when the hovercraft is sailing upright, effectively improving the hovercraft's stability. Furthermore, the lift difference between the rudder blades can be used to provide sufficient steering force during turns.

Description

Technical Field

[0001] This invention relates to hovercraft, and more particularly to an air rudder for use on a small hovercraft in conjunction with an inner and outer ring-type air propeller. Background Technology

[0002] A hovercraft is a high-speed vessel that uses the surface effect principle to create an air cushion, allowing the hull to detach from its supporting surface and achieve navigation. Hovercraft primarily rely on airflow in two opposing directions for propulsion: the airflow at the bottom forms an air cushion that lifts the hull, while the airflow at the rear provides thrust. Large hovercraft can generate these two airflows using different engines; however, smaller hovercraft, due to limited space, generally rely on a single engine combined with airflow deflectors to direct the airflow in different directions. An inner and outer annular ducted air propeller is one such device used in small hovercraft.

[0003] The inner and outer ring ducted air propeller divides the duct into inner and outer rings. The inner ring directs some airflow to the outer ring to provide propulsion, while the outer ring introduces airflow into the pressurization chamber to provide lift. Hovercraft require as smooth and uniform airflow as possible into the pressurization chamber, but the airflow generated by the air propeller is spiral-shaped, resulting in inconsistent airflow on both sides. Therefore, guide vanes are needed on one side to change the airflow direction, but this generates additional lateral drift force, such as... Figure 1 As shown in P, this results in poor directional stability for small hovercraft, which greatly affects their ability to increase speed and their widespread adoption. Summary of the Invention

[0004] The purpose of this invention is to provide an asymmetric air rudder for the inner and outer ring air propellers of hovercraft that can reduce the influence of sideslip force, thereby improving the stability of small hovercraft navigation.

[0005] The asymmetric air rudder for the inner and outer ring air propeller of the hovercraft described in this invention includes three rudder blades arranged opposite to the air propeller. The cross-sectional shape of the rudder blades is that of an aircraft airfoil. The three rudder blades are arranged side by side, with the middle rudder blade being a positive rudder blade in the same direction as the lateral drift force, and the two side rudder blades being negative rudder blades in the opposite direction to the lateral drift force.

[0006] Furthermore, the three rudder blades are rotatably mounted on the air propeller and positioned opposite the air propeller's outlet.

[0007] Furthermore, there is a rudder bracket fixedly mounted on the air propeller, and all three rudder blades are mounted on the rudder bracket via a linkage. There is also a driver that drives the three rudder blades to rotate synchronously via the linkage.

[0008] Furthermore, the airfoil of the rudder blade satisfies the following formula:

[0009] The asymmetric air rudder used in the inner and outer ring-type air propeller of the hovercraft described in this invention has three rudder blades arranged opposite to the air propeller on the hovercraft, and arranged sequentially along a straight line as a counter-rotating rudder blade, a forward rudder blade, and a counter-rotating rudder blade. When the hovercraft is moving forward, the rudder blades do not deflect, and all three rudder blades generate lift. The lift generated by the forward rudder blade is opposite in direction to that of one of the counter-rotating rudder blades, thus canceling each other out. The remaining rudder blade interacts with the lateral drift force and cancels it out. When the hovercraft turns left, the three rudder blades swing in the same direction at the same angle, with the airfoil of the middle forward rudder blade being negative. At the first angle of attack, no lift is generated. The airfoils of the two opposing rudder blades have a positive angle of attack and will generate lift. This lift will not only counteract the sideslip force but also generate a steering force. Together with the fluid resistance experienced by the hovercraft, this will form a steering moment, thus achieving a left turn. When the hovercraft turns right, the three rudder blades swing synchronously in the other direction, causing the airfoils of the two opposing rudder blades to change to a negative angle of attack and generate no lift. The airfoil of the middle positive rudder blade changes to a positive angle of attack and generates lift. The lift of this rudder blade, together with the sideslip force, will form a steering force. Together with the fluid resistance experienced by the hovercraft, this will form a steering moment, thus achieving a right turn. This type of hovercraft uses an asymmetric air rudder with an inner and outer ring air propeller. The rudder blades are essentially vertical airfoils. When the airfoil has a positive angle of attack, it will generate corresponding lift, while when the airfoil has a negative angle of attack, it will not generate lift or will generate very little lift, which will not have a significant impact on navigation. Therefore, by using the shape and orientation of the three rudder blades, the lateral drift force generated by the air propeller can be counteracted when the hovercraft is sailing upright, thereby effectively improving the stability of the hovercraft. The lift difference of the rudder blades can also be used to provide sufficient steering force when turning. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of an air propeller and the lateral drift force it generates.

[0011] Figure 2 This is a schematic diagram of the asymmetric air rudder used in the inner and outer ring air propellers of a hovercraft.

[0012] Figure 3 yes Figure 2 The diagram shows the structure of the three rudder blades in the A direction of the asymmetric air rudder used in the inner and outer ring air propellers of the hovercraft.

[0013] Figure 4 , 5 This is a diagram showing the relative positions of the three rudder blades and the air propeller when the hovercraft turns. Detailed Implementation

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0015] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, top, bottom, inside, outside, vertical, horizontal, longitudinal, counterclockwise, clockwise, circumferential, radial, axial, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0016] If the embodiments of this invention involve descriptions such as "first" or "second," such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0017] This invention proposes an asymmetric air rudder for an inner and outer ring-type air propeller of a hovercraft.

[0018] The asymmetric air rudder for the inner and outer ring air propeller of the hovercraft in this embodiment includes three rudder blades 2 arranged opposite to the air propeller 1. The cross-sectional shape of the rudder blades is that of an aircraft airfoil. The three rudder blades are arranged side by side, and the middle rudder blade is a positive rudder blade 3 that is in the same direction as the lateral drift force, while the two side rudder blades are negative rudder blades 4 that are opposite to the direction of the lateral drift force.

[0019] like Figure 2 , 3 As shown, the rudder blade is essentially a vertical wing. When the wing has a positive angle of attack, it will generate corresponding lift. When the wing has a negative angle of attack, it will not generate lift or will generate very little lift, which will not have a significant impact on navigation. The three rudder blades are rotatably mounted on the air propeller and are positioned opposite to the air outlet of the air propeller. The three rudder blades are distributed at intervals along a straight line, and are in the order of reverse rudder blade, forward rudder blade, and reverse rudder blade.

[0020] When the hovercraft moves forward, as Figure 3As shown, the rudder blades do not deflect; all three blades generate lift L. The upper counter-rotating rudder blade generates lift in the opposite direction to the middle forward-rotating rudder blade, thus canceling each other out. The lower counter-rotating rudder blade interacts with and cancels out the lateral drift force P. When the hovercraft turns left, as... Figure 4 As shown, the three rudder blades swing in the same direction at the same angle. The middle positive rudder blade has a negative angle of attack and does not generate lift. The upper and lower negative rudder blades have positive angles of attack and will generate lift L. This lift, while counteracting the lateral drift force P, can also generate a steering force, which, together with the fluid resistance experienced by the hovercraft, forms a steering moment, thus achieving a left turn. When the hovercraft turns right, as... Figure 5 As shown, the three rudder blades swing synchronously in another direction, causing the airfoil of the two opposing rudder blades to change to a negative angle of attack and not generate lift, while the airfoil of the middle positive rudder blade changes to a positive angle of attack and generates lift L. The lift of this rudder blade, together with the lateral drift force, constitutes the steering force, which, together with the fluid resistance experienced by the hovercraft, constitutes the steering torque, thus achieving a right turn.

[0021] The aforementioned air-cushion vehicle uses an asymmetric air rudder for its inner and outer ring-type air propeller. It has a rudder bracket 5 fixedly installed on the air propeller 1, and three rudder blades 2 are all installed on the rudder bracket through a linkage 6. There is also a driver (not shown) that drives the three rudder blades to rotate synchronously through the linkage, thereby ensuring the accuracy of the synchronous rotation of the three rudder blades and simplifying the structural complexity to better adapt to the use of small air-cushion vehicles.

[0022] The aforementioned hovercraft uses an asymmetric air rudder for its inner and outer annular air propellers, and the airfoil of the rudder blades satisfies the following formula:

[0023] In the formula, L represents the lift of the rudder blade; C L ρ is the lift coefficient of the rudder blade. a V is the air density; V is the slip velocity of the duct on the air propeller; A is the projected area of ​​the rudder blade.

[0024] The steering force of a hovercraft turning left is 2Lcosθ-F (θ is the airfoil angle of attack of the rudder blade, i.e., the limiting yaw angle, and F is the yaw force of the hovercraft during navigation), and the steering force turning right is Lcosθ+F. To ensure that the steering forces on both sides of the hovercraft are consistent, it is necessary to ensure that 2Lcosθ-F=Lcosθ+F, that is, L=2F / cosθ; when sailing forward, it is necessary to ensure that L+F=2L, that is, L=F; when turning, it is at a large angle of attack, usually within the stall angle of attack range, and the lift coefficient increases with the increase of the angle of attack.

[0025] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An asymmetric air rudder for an inner and outer ring-type air propeller of a hovercraft, characterized in that: The system includes three rudder blades (2) arranged opposite to the air propeller (1), with the cross-sectional shape of the rudder blades being an airfoil. The three rudder blades are arranged side by side, with the middle rudder blade being a forward rudder blade (3) aligned with the direction of the lateral drift force, and the two side rudder blades being reverse rudder blades (4) aligned with the direction of the lateral drift force. The three rudder blades (2) are rotatably mounted on the air propeller (1) and are arranged opposite to the air outlet of the air propeller. When the hovercraft travels forward, the three rudder blades (2) do not deflect. When the hovercraft turns left or right, the three rudder blades swing in the same direction at the same angle.

2. The asymmetric air rudder for the inner and outer annular air propeller of the hovercraft according to claim 1, characterized in that: There is a rudder bracket (5) fixedly installed on the air propeller (1), and three rudder blades (2) are all installed on the rudder bracket through a linkage (6). There is also a driver that drives the three rudder blades to rotate synchronously through the linkage.

3. The asymmetric air rudder for the inner and outer annular air propeller of a hovercraft according to claim 1 or 2, characterized in that: The airfoil of the rudder blade satisfies the following formula: In the formula, L represents the lift of the rudder blade; C L The lift coefficient of the rudder blade; ρ is the air density; v is the slip velocity of the duct on the propeller; A is the projected area of ​​the rudder blade.

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