GB2591135A

GB2591135A - Limited rotation aerofoil

Info

Publication number: GB2591135A
Application number: GB2000741.5A
Authority: GB
Inventors: Jayes Jim
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-01-17
Filing date: 2020-01-17
Publication date: 2021-07-21
Also published as: GB202000741D0

Abstract

An aerodynamic foil, such as an aerofoil or a hydrofoil, has a body 10 with a pivot axis located within the body. The pivot axis is parallel to a length of the body and perpendicular to a depth of the body, and the body has a limited range 13 of rotation about the pivot axis. The pivot axis may be provided on a pivot bar 11, to which may be secured a resistance element 12 such as a spring, a wedge, a hydraulic element or a rubber device. Any resistance element may be adjustable and may allow the foil to be secured in a non-neutral position; suitably, when in such a position, the device can act as a sail in a crosswind. The device may be mounted on a vehicle or on a stationary object or building. Body 10 may have a teardrop shape.

Description

Limited Rotation Aerofoil [1] The present invention relates to an aerofoil having a limited rotation about an axis. In particular an aerofoil having a limited rotation about an axis in order to improve performance while subject to a crosswind in comparison to the performance of fixed aerofoils in a crosswind.

Background of the Invention

[2] In competitive racing, from cycling, to sailing and beyond, aerodynamics is very important. The reduction in drag can give a competitor the edge needed to beat their competition. The reduction of drag in general is often beneficial as it can improve efficiency and therefore the performance of anything that in operation loses energy to drag while moving through a fluid.

[003] At subsonic speeds, the most aerodynamic shape is a teardrop shape. 'the teardrop has a rounded nose that tapers as it moves backward, forming a narrow, yet rounded tail, which gradually brings the air around the object back together instead of creating eddy currents.

[004] Aerofoils/hydrofoils have a roughly teardrop like cross section. The rounded end of the teardrop being known as the leading edge of the aerofoil and the narrower more pointed end of the teardrop being known as the trailing edge of the aerofoil. 'this shape is optimum for moving through a stable calm fluid, be it air or liquid. The term aerofoil is generally used when moving through air, hydrofoil is generally used when moving through a liquid. In this application, for clarity, unless the fluid medium is specified as a liquid, the term aerofoil will be used.

[005] There is a condition where an acrofoil's aerodynamic effectiveness is greatly reduced. This condition is when there is a notable crosswind/crosscurrent to the direction of travel. In crosswinds the aerofoils ability to reduce drag is greatly diminished, and in extreme occasions its presence can create more drag than if it wasn't there.

[006] The object of the current invention is to provide an aerofoil/hydrofoil with limited rotation about an axis. Such that when a crosswind is incident on the aerofoil, the aerofoil can rotate slightly about the axis and therefore, partially to completely, mitigate the reduction in performance that would be experienced if the aerofoil were in a fixed position in a crosswind.

Statement of Invention

[7] An aspect of the invention provides an aerodynamic foil comprising a body having a pivot axis located within the body. The pivot axis being parallel to a 5 length of the body and perpendicular to a depth of the body. The body of the aerodynamic foil having a limited range of rotation about the pivot axis.

[8] The aerodynamic foil wherein the body is substantially hollow, rotatably mounted within the body at the location of the pivot axis is a pivot bar. Secured to 10 the pivot bar there is a resistance means, the resistance means limiting the range of rotation of the body about the pivot axis.

[9] The aerodynamic foil wherein the resistance means secured to the pivot bar may be in the thrm of at least one spring. Respective ends of the spring are touching, or nearly touching opposing internal walls of the body, wherein the spring acting against the internal walls of the body, urging the body to a general neutral position.

[10] The aerodynamic foil wherein the resistance means secured to the pivot bar may be in the form of at least one wedge extending from the pivot bar into an internal cavity of the body towards the trailing edge of the body. The wider end of the wedge proximal the pivot bar and the narrow end of the wedge distal the pivot bar. The body being able to pivot around the pivot bar until an internal wall of the body makes contact with the wedot [11] The aerodynamic foil wherein the resistance means is formed of high-qua]ity rubber. Such that when under external cross forces the aerofoil partially deforms the rubber resistance means and therefore pivots about the pivot axis to an improved aerodynamic position.

[12] The aerodynamic foil wherein the resistance means secured to the pivot bar comprises hydraulics.

[13] The aerodynamic foil, wherein the resistance elements may be adjustable so as to adjust the possible range of rotation of the aerodynamic foil.

[14] The aerodynamic foil, wherein the adjustable resistance elements may also releasably fix the aerodynamic foil in a non-neutral position.

[15] The aerodynamic foil wherein the body may comprise: a leading edge 40 running parallel with the length and an opposing trailing edge. The distance between the two edges defining the depth of the body. The body further comprising a substantially teardrop shaped cross-section in the plane perpendicular to the length of the body.

10161 The aerodynamic foil may be mounted on a vehicle for the reduction of drag forces.

10171 The aerodynamic foil may be mounted on a stationary object/building for the reduction of drag forces.

10181 The aerodynamic foil wherein the aerodynamic foil may be an aerofoil.

10191 An aerodynamic foil wherein the aerodynamic foil may be a hydrofoil.

Brief Description of the Drawings

10201 The invention will be described, by way of example only, with reference to the drawings, in which: [021] Figure 1 is a cross-section of an example embodiment comprising a spring.

10221 Figure 2 is a cross-section of an example embodiment comprising a wedge.

10231 Figure 3 is an example embodiment of the invention in use on the rudder of the boat.

Detailed Description of the Drawings

[0241 Regarding figure 1 there is an aerofoil 10 of any known body shape design, having a leading edge 14 and a trailing edge 15. The aerofoil is rotatably secured to a pivot bar 11. Attached by any known suitable means to the pivot bar 11 is a resistance means 12. In the particular embodiment shown in figure 1 the resistance means 12 is a spring.

10251 In use when mounted on an object, the pivot bar 11 is fixed in place on the object the aerofoil is to be mounted on. The resistance means (spring) 12 is secured to the pivot bar, holding the external aerofoil 10 in a neutral (zero crosswind) position in relation to the pivot bar 11 and the object the pivot bar 11 is mounted to. When a cross-force, for example a crosswind, is incident on the aerofoil 10 with enough force to overcome the restorative force of spring 12. The aerofoil 10 partially rotates about the rotation axis so as to be in a more aerodynamic position in relation to the incident crosswind and therefore reduce the drag forces acting upon the aerofoil and the object it is mounted to. Once the crosswind force subsides, the spring urges the body of the aerofoil 10 to its neutral position.

[26] The resistance means (e.g. spring) 12 is attached to the pivot bar 11 by any suitable means. The resistance means 12 positioned such that it allows limited rotation of the aerofoil about pivot bar 11 to a more efficient aerodynamic position with regards to the direction of travel and the incident crosswind. The trailing edge of the aerofoil having a range of movement defined by arrows 13. ilbe size of this range of movement dependant on the specific use of the aerofoil.

[27] Figure 2 relates to an alternate embodiment of the invention. Aerofoil 20 is pivotably mounted on pivot bar 21, where a resistance device 22 is secured to the pivot bar 21. In this embodiment the resistance device is a wedge 22. Wedge 22 can be made out of any suitable material for example plastic, hard rubber etc. In use the aerofoil 20 can pivot freely in the range permitted by the wedge 22, the trail edge being able to move in the range 23, and internally the aerofoil 20 can rotate about the pivot bar 21 until an internal surface wall of the aerofoil body 20 makes contact with the wedge 22, this range of movement is defined by arrows 24.

[28] Figure 3 depicts a cross-sectional view of an example embodiment in use with a rudder of a boat. The boat 33 has a rudder 32 attached to the bottom of it.

Mounted on the rudder 32 is the invention 30. The hydrofoil 30 is attached to the rudder 32 via pivot bar 31. Resistance means 35 fixed on pivot bar 31 restricting movement of the trail edge of the hydrofoil to the range 34. The partial rotation of the hydrofoil 30 would aid in limiting the bobbing that is experienced by boats and therefore improve the efficiency of the boat.

[29] Another example embodiment not shown in the figures comprises the aerofoil being formed of durable high-quality rubber. The aerofoil itself being able to deform slightly under an incident cross-force and therefore achieve a more aerodynamic position.

[30] Other resistance elements alternative to a spring or a wedge can be employed to limit the rotation of the aerofoil about the axis, for example hydraulic controls etc. [031] 'File allowed range of rotation of the aerofoil can be adjustable. This may be achieved by the resistance element itself being adjustable. By providing a plurality

S

of resistance elements, or the resistance elements being replaceable with other resistance elements etc. or any other method of adjustment obvious to the skilled person.

[032] The aerofoil may also be able to be releasably fixed in a non-neutral position by the resistance elements. When fixed in a non-neutral position the aerofoil can act in a similar way to a sail to provide additional forward drive.

[33] The described invention would be of use to anything which requires less air or water resistance. For example, with use on sailboat rigging reducing the air resistance and drag of the rigging, therefore improving the performance of the sailboat. By fixing the aerofoils on the sailboat rigging in a non-neutral position they can also be used as discussed above to add additional drive, further improving performance.

[34] The limited rotation aerofoil could be used on all types of vehicles for both improving general efficiency as well as high end performance sporting competition uses. It could also be used with electric vehicles; improved aerodynamics reduces energy consumption and therefore helps in increasing the range and performance of the electric vehicle.

[35] Advantages provided by use of a limited rotation aerofoil are not just limited to vehicles. The invention is completely scalable. Standing objects such as wind turbine towers etc, which are subject to stress from strong winds, could benefit from a partially rotating aerofoil to help reduce the stress due to wind resistance.

[36] The invention has been described with reference to a preferred embodiment The description is intended to enable a skilled person to make the invention, not to limit the scope of the invention. The scope of the invention is 30 determined by the claims.

Claims

Claims 1. An aerodynamic foil comprising a body having a pivot axis located within the body, the pivot axis being parallel to a length of the body and perpendicular to a depth of the body; the body having a limited range of rotation about the pivot axis.
2 An aerodynamic foil according to claim 1 wherein the body is substantially hollow, rotatably mounted within the body at the location of the pivot axis is a pivot bar, secured to the pivot bar there is a resistance means, the resistance means limiting the range of rotation of the body about the pivot axis.
3 An aerodynamic foil according to claim 2 wherein the resistance means secured to the pivot bar is in the form of at least one spring, respective ends of the spring touching, or nearly touching opposing internal walls of the body, the spring urging the body to a g,eneral neutral position.
4. An aerodynamic foil according to claim 2 wherein the resistance means secured to the pivot bar is in the form of at least one wedge extending from the pivot bar into the internal cavity of the body towards the trailing edge, the wider end proximal the pivot bar and the narrow end of the wedge distal the pivot bar, the body being able to pivot around the pivot bar until an internal wall of the body makes contact with the wedge
5 An aerodynamic foil according to claim 1 wherein the resistance means is formed of high-quality rubber. Such that when under external cross forces the aerofoil partially deforms the rubber resistance means and pivots about the pivot axis to an improved aerodynarnic position.
6. An aerodynamic foil according to claim 2 wherein the resistance means secured to the pivot bar comprises hydraulics.
7. An aerodynamic foil according to any preceding claim wherein the resistance elements are adjustable so as to adjust the possible range of rotation of the aerodynamic foil.
8 An aerodynamic foil according to claim 7 wherein the adjustable resistance elements can also releasably fix the aerodynamic foil in a non-neutral position.
9 An aerodynamic foil according to claim 8 wherein when the foil is fixed in non-neutral position, it can act like a sail in a crosswind and provide a driving force.
10. An aerodynamic foil according to any preceding claim wherein the body comprises: a leading edge running parallel with the length and an opposing trailing edge, the distance between the two edges defining the depth of the body; the body further comprising a substantially teardrop shaped cross-section in the plane perpendicular to the length of the body.
11. An aerodynamic foil according to any preceding claim mounted on a vehicle for the reduction of drag forces.
12. An aerodynamic foil according to any one of claim 1 to 10 mounted on a stationary object/building for the reduction of drag forces.
13. An aerodynamic foil according to any preceding claim, wherein the aerodynamic foil is an aerofoil.
14. An aerodynamic foil according to any preceding claim, wherein the aerodynamic foil is a hydrofoil.