GB2472023A

GB2472023A - Steering flying vehicle by control of aerofoil

Info

Publication number: GB2472023A
Application number: GB0912652A
Authority: GB
Inventors: Simon Mcintosh
Original assignee: Aesir Ltd
Current assignee: Aesir Ltd
Priority date: 2009-07-21
Filing date: 2009-07-21
Publication date: 2011-01-26
Also published as: GB0912652D0; WO2011010155A4; WO2011010155A3; WO2011010155A2

Abstract

A craft comprises a canopy 1 defining a lift-producing surface 1A shaped to have double curvature. An engine 2 is supported beneath the canopy 1 driving a radial fan impeller 3. Aircraft are usually provided with moveable aerofoils as a means to control direction and orientation. On fixed wing craft these commonly take the form of hinged vanes or ailerons. In Coanda craft the vanes are usually hinged to the skirt of the canopy. The invention offers an alternative method of steering in which the aerofoil is flexible and that the craft has means to cause the aerofoil to flex. Actuators 5 act cause threaded rods 4 to flex a selected portion of the canopy 1 so as to cause the craft to pitch or roll. The airfoil may be formed from a single integral piece formed from a composite material having a varying composition so as to give different portions of the aerofoil different levels of flexibility. The craft may be submersible.

Description

Steering Vehicles Through Control of Aerofoils The present invention was originally conceived for use with Coanda aircraft though may be applicable to other craft.

Aircraft are usually provided with moveable aerofoils in order that the direction and orientation of craft can be controlled. On a fixed wing craft these commonly take the form of hinged vanes or ailerons. In a Coanda craft such as described in W02006/100525, the vanes are hinged to the skirt of the canopy and moved by actuators in order to control pitch and roll.

According to the invention there is provided a craft having an impeller to cause fluid to flow radially outward from a central position over a curved surface, this surface serving to divert the radial flow towards an axial direction thereby generating lift; characterised by an aerofoil that is flexible and in that the craft comprises means to cause the aerofoil to flex.

In this specification an aerofoil includes any surface such as a wing, aileron or stabilizer designed to aid in lifting or controlling a craft by making use of the fluid currents through which it moves or which are moved over it.

In a preferred embodiment, at least a portion of, the surface which is defined by a canopy of the craft, is flexible and the craft comprises means to flex the surface so as to alter the lift generated by the surface. Selected portions of the surface may then be flexed to cause the craft to pitch or roll as required. Alternatively or additionally the aerofoil may be located on or adjacent the surface, in such instances the aerofoil may be used to control yaw of the craft.

In order to cause the surface to flex the craft may comprise actuators housed underneath the lift generating surface. The actuators may comprises longitudinal members such as cables or rods anchored to various points on the non-lift producing side of the canopy and torsions which upon the signal of a control system can pulled in or let out the rods or cable so as to cause a region approximate the anchor point to flex.

The surface could be defined by a canopy formed from a single integral piece of composites material; this composite material may be formed with a variable composition throughout the piece so that different portions of the body have different flexibilities. Preferably the piece would be formed such that the portion of the piece forming a crown of the canopy is relatively stiff whereas the portion of the piece forming the lower free edge or skirt is relative flexible to allow flexing by the actuator. The canopy can be made from a polymer material such as a settable resin reinforced by fibres eg of glass, carbon or Kevlar. The composition may vary to give the required varying flexibility over the surface of the canopy.

The invention will now be described by way of example with reference to the following figure which is a cross-section through a vertical axis of a vertical take-off craft.

The craft comprises a canopy 1 defining a lift-producing surface 1A and shaped to have double concave curvature. An engine 2 is supported beneath the canopy and drives a radial fan impeller 3. This draws air or water (if a submersible craft) , in the direction as identified by arrows A, into a space defined between the canopy 1 and an annular shroud 4. The air is then expelled over the surface 1A which, because of the Coanda effect, diverts the air jet from a radial to a generally axial direction thereby generating lift.

The canopy 1 is formed from a single integral piece of composite material formed from resin reinforced with glass and carbon fibres. The composite material is formed such that its composition and its thickness varies from the crown of the canopy, directly underneath the impeller, to the free edge or skirt of the canopy. The crown portion is formed having a relatively high thickness and a high proportion of carbon fibre which provides relatively high rigidity. The skirt portion has a relative low proportion of carbon fibre but an increase proportion of glass fibre and as a consequence is relatively flexible compared with the crown. The proportions of glass fibre and carbon fibre may decrease / increase respectively from the crown to the skirt or may change in a stepwise fashion.

Threaded rods 4 are anchored at points circumferentially about the inner side of the canopy 1 close to the skirt. One or more torsion actuators 5 support the opposing ends of the rods 4.

The actuator 5 responds upon the output signal of a steering control (shown schematically at 6) to rotate a rod 4 so as to cause the rod to be pulled inwards This, in turn causes the skirt of the canopy to flex inwardly in the region surrounding the anchor point. This flexing causes the lift generated by that region of the canopy to change thereby inducing the craft to change direction. Similarly the rod may be pushed outward cause the converse effect.

The steering control 6 includes a gyroscope to measure movement of the craft from a datum position and a comparator to compare the direction indicated by the gyroscope with a desired direction. The resulting error signal from the comparison forms the output signal of the steering control.

The increasing stiffness of the canopy 1 towards the crown provides the canopy 1 with sufficient rigidity to maintain its shape. The higher carbon fibre content within the skirt region provides resilient flexibility to allow the canopy to flex upon movement of the rods 4.

Spaced circumferentially on the upper surface of the canopy are vanes 7 (only two shown in the Figure) used to control yaw of the craft and correct counter spin caused as a consequence of rotation of the impeller 3. Each vane 7 is formed from a piezoelectric bender element similar in principle with that described in patent specification W084/05010. It is supported on a post 4A and made of layers of piezoelectric material arranged so that the vane bends, due to the piezoelectric effect, when an electric potential is applied from the control circuit 6.Thus, the application of an electric field across the layers of the vane7 causes the latter to mechanically deform thereby reducing or increasing the aerodynamic lift generated by the vane and any circumferential component of movement of the air jet over the Coanda surface.

In alternative embodiments, the rods 4 could be replaced by cables and torsioned by a winch; or the required distortion of the surface of the canopy could be provided by electric, possibly piezoelectric, actuators. The skirt may be formed separately from the remainder of the canopy, this separate skirt portion being formed from a resiliently flexible synthetic plastics material.

In a further alternative a skirt portion of the canopy may be formed from the piezoelectric material described before, possibly in the form as a series of plates supported from the edge of the canopy and whose shape can be individually controlled by selective application of an electric field.

Claims

Claims 1. A craft having an impeller to cause fluid to flow radially outward from a central position over a curved surface, this surface serving to divert the radial flow towards an axial direction thereby generating lift; characterised by an aerofoil that is flexible and in that the craft comprises means to cause the aerofoil to flex.
2. A craft according to Claim 1 wherein the surface is flexible and that the craft comprises means to flex the surface so as to alter the lift generated by the surface.
3. A craft according to Claims 1 wherein the aerofoil is located on the surface.
4. A craft according to Claim 2 or 3 comprising means to selectively flex a portion of the aerofoil or surface so as to change the orientation of the craft.
5. A craft according to Claim 2 or 4 when dependent on claim 2 wherein the surface comprises a flexible skirt portion located at a downstream point on the surface.
6. A craft according to claim 5 comprising an actuating member linked to an inner point of the canopy and means to actuate the member so to flex a portion of the canopy surround the linking point draw the canopy inwards or outwards.
7. A craft according to any previous claim the aerofoil is formed from a single integral piece composite material
8. A craft according to claim 8 wherein the composition of the composite varies throughout piece such as to make a portion of the aerofoil more flexible than a second portion of the aerofoil.
9. An aerofoil formed from a single integral piece flexible composite material and means to cause the aerofoil to flex so as to alter the aerofoil's lift characteristics.
10. An aerofoil according to claim 9 wherein the composite has a composition which varies throughout the single integral piece such as to make a first portion of the aerofoil stiffer than a second portion of the aerofoil.
11. An aerofoil according to claim 10 wherein the composite comprises a fibre reinforced polymer material.