AU605662B2

AU605662B2 - Wingsail control systems

Info

Publication number: AU605662B2
Application number: AU27084/88A
Authority: AU
Inventors: John Graham Walker
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-05-02
Filing date: 1988-12-15
Publication date: 1991-01-17
Anticipated expiration: 2006-05-02
Also published as: AU602621B2; AU2699488A; AU605948B2; AU2699588A; AU2708488A

Description

E B. RICE CO PATENT

ATTORNEYS

This form is suitable for any type of Patent Application. No logalisation roquired.

COMMONWEALTH OF AUSTRAL^ Patent Act 1952 COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number Lodged Complete Specification Lodged Accepted Published Priority: Related Art Name of Applicants Address of Applicants Actual Inventor Address for Service JOHN GRAHAM WALKER and

WALKER

JEAN MARGARET S Both of Tipwell House, St. Mellion, Cornwall PL12 6RS, England S JOHN GRAHAM WALKER F.B. RICE CO., Patent Attorneys, 28A Montague Street, BALMAIN. 2041.

Complete Specification for the invention entitled: "WINGSAIL CONTROL SYSTEMS" The following statement is a full description of this invention including the best method of performing it known to Us:- S0043)- I5/1 2/8: i!~ U la This invention relates to aerofoils, and especially to wingsail aerofoils.

The wingsail systems with which the present invention is concerned are generally of the self setting type that are mounted freely for rotation about an upright axis. In a 1 0 wingsail system with a multi-element wing comprising a leading element and a trailing element or flap positioned closely behind the leading element and pivotable to each side to form respective composite cambered configurations, the moment on the hinge of the flap due to airflow is considerable, and must be resisted if the cambered J configuration is to be maintained. If a hydraulic ram is used to drive the flap and maintain its position, this necessitates use of a ram large enough to withstand the maximum moment likely to be encountered. A locking device may be employed in order to relieve the ram once the flap is fully deflected, but the hydraulic ram still has to be large in order to defect the flaps in a strong airstream.

Aircraft flaps incorporate devices such as rails and fixed pivots in order to alleviate any analogous problems, however this method is not easily adaptable for wingsail systems because, unlike aircraft flaps, the flap must be capable of deflection in both directions in order to operate on both tacks.

9 In a wingsail rig comprising multi-element wings of which one element is deflected relative to another, it is generally desirable for the moving elements to be capable of deflection each way from a central aligned position. It is usually the object for wingsails to exhibit similar capability on both port and starboard tacks and for this

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2 purpose arrangements capable of adopting mirror image configurations are favoured. The thrust wings may be trimmed by a control aerofoil such as a tail vane.

The present invention is also directed towards providing a system that will deflect a moving aerofoil with equal speed in each direction, and towards providing a failsafe system for aerofoil movement.

According to the present invention there is provided a compound wingsail assembly comprising a symmetrical upright 0 leading aerofoil having a leading edge and a trailing edge and a symmetrical upright trailing aerofoil having a leading edge and a trailing edge, the leading edge of the trailing aerofoil being positioned closely behind the trailing edge of the leading aerofoil and means for mounting the trailing aerofoil for pivoting movement about an upright axis in the plane of symmetry of the leading aerofoil from an aligned position in which the trailing aerofoil is coplanar with the leading aerofoil to positions to each side of and angularly displaced from said aligned position in which the trailing aerofoil is moved to and from said angularly displaced positions by at least one pair of double-acting fluid operated cylinders, each cylinder having a piston separating an annulus side of the cylinder through which a piston rod passes from a full bore side of the cylinder, the cylinders being connected so that the trailing aerofoil is moved by co-operative action of a first one of said pair of cylinders on an extending stroke and a second one of said pair of cylinders on a contracting stroke and in which fluid flow during movement of the trailing aerofoil is simultaneously to the annulus side of one cylinder of the pair and to the full bore side of the other cylinder of the pair.

The invention also provides a self trimming wingsail I 3 assembly comprising a thrust wing having a symmetrical upright leading aerofoil having a leading edge and a trailing edge and a symmetrical upright trailing aerofoil having a leading edge and a trailing edge, the leading edge of the trailing aerofoil being positioned closely behind the trailing edge of the leading aerofoil, means for mounting the trailing aerofoil for pivoting movement about an upright axis in the plane of symmetry of the leading aerofoil from an aligned position in which the trailing aerofoil is 1 0 coplanar with the leading aerofoil to positions to each side °ooa of and angularly displaced from said aligned position, and a symmetrical tail aerofoil, the assembly being freely oO rotatable about an upright axis and the tail aerofoil being capable of deflection to each side of an aligned position parallel with the leading aerofoil in order to rotate the o aerofoii assembly about said upright axis to a corresponding angle of attack to the wind, and means for deflecting the tail aerofoil comprising at least one pair of double-acting fluid operated cylinders, each cylinder having a piston separating an annulus side of one cylinder through which a piston rod passes from a full bore side of the cylinder, the cylinders being connected so that the tail aerofoil is moved by co-operative action of a first one of said pair of cylinders on an extending stroke and a second one of said pair of cylinders on a contracting stroke and in which fluid flow is simultaneously to the annulus side of one cylinder of the pair and to the full bore side of the other cylinder of the pair.

The invention is now described by way of example with reference to the accompanying drawings in which: Figure 1 is a schematic diagram of a two section wingsail showing the hinge moment; -4 4 4 Figure 2 is a schematic diagram of a self trimming wingsail rig with all aerofoils aligned; Figure 3 is a diagram of a hydraulically operated pinlock; Figures 4 to 6 are a schematic diagrams of a self trimming wingsail rig undergoing flap deflection; Figure 7 is a schematic diagram of a self trimming wingsail rig with a governor vane set for trimming; Figure 8 is a flow diagram for a control system for changing Socamber; Figure 9 is a schematic plan view of a two element wingsail o in the symmetrical position; Figure 10 and 11 are schematic plan views of the wingsail of o Figure 9 in cambered configurations; Figure 12 is a schematic plan view of a hydraulic system o according to the invention, and Figure 13 is a perspective view of the wingsail assembly of Figure 9.

L i 5 Referring to Figure 1 a wingsail comprising a leading aerofoil 1 and a trailing aerofoil flap 2 is shown with the flap 2 deflected. The airflow, shown generally by the arrow 3, creates a positive pressure on the flap tending to rotate the flap away from its deflected position as shown by arrow 4. It will be seen that the movement of the flap is resisted by a hydraulic ram 5 (or some other operating device). A pinlock, or other device may be incorporated in order to relieve the stress on the hydraulic system during tacking, but never-the-less the flap moving system is still subject to stress when moving the flap in a strong airstream, and unless it is very heavy (and therefore expensive) may become overstressed before the position is reached at which the pin can be inserted.

In order to reduce the stress on the hydraulic system when the flaps are being deflected, a method of operating a self trimming wingsail system has been devised in which the trimming system is operated in order to reduce the moment opposing movement about the flap hinges. A self-trimming wingsail is one in which a control aerofoil, preferably in the form of a tail vane mounted on a boom is used to trim the main aerofoil, the desired angle of attack being set by the relative deflection to the tail vane which then trims the main aerofoil wings and retrims during changes in angle of attack. The method of operating the self-trimming rig to reduce flap hinge moments comprises, for a tail vane system, deflecting the tail vane to full deflection on the same side as that to which it is intended to deflect the flap on the main aerofoil wing. This will rotate the main aerofoil so that the resistive moment on the flap is much reduced, or even eliminated and replaced by a moment assisting deflection. The flap once deflected, is locked and the tail vane readjusted to trim to the desired angle of attack.

L 6 This sequence is shown in Figures 4 to 7, commencing from a position shown in Figure 2 in which the tail vane designated by reference 6 is aligned with the main wing, of which both aerofoil sections 1 and 2 are also aligned and weathercocked to the wind. In general a plurality of wings will be arranged alongside each other and be interconnected to be rotated as a unit by the tail vane, with the flaps interconnected to move together. The device for moving the flaps may then be mounted on a stay interconnectiong the wings, as shown in Figure 2 with hydraulic ram 5 mounted on a spar 7.

In Figure 4 the tail vane has been deflected to its maximum position in one direction (down as viewed) and by virtue of the tail vane realigning itself to the wind it rotates the main wing system about its axis as shown in Figure Deflection in the downward as viewed direction of the flap 2 to the position shown in Figure 6 is now aided by the wind, and upon achieving maximum deflection the flap 2 is locked in position and the moving mechanism relieved of stress.

Figure 7 shows the tail vane set at a different angle to trim the main wing to the desired angle of attack.

The same procedure can be repeated in reverse for the other tack.

Preferably the sailing conditions are monitored continually and a control system including a microprocessor ascertains whether a change of camber, such as for changing tack, is required. Figure 8 shows a simplified flow diagram for a change of tack control system. In the diagram the tail and flap movements are linked, however in practice it may be preferable to treat these separately and interrogate 'is tail lock out' with the command 'move tail' following the affirmative, and the interrogation 'is flap lock out' Ohl 7 followed by 'move flap' for the respective affirmative response.

The system of operation described above is the subject of our co-pending application No The preferred connection for the fluid cylinders, in accordance with the present invention, is now described.

.00 Referring to Figure 9 a wingsail is shown that comprises a leading element 1 and a trailing flap 2. The flap 2 can be deflected about a pivot to adopt the positions shown in 000 0 Figures 10 and 11, the deflection being controlled by a 0 system incorporating a fluid cylinder such as a hydraulic ram. A problem with using a hydraulic ram is that during the inward stroke of ihe ram into the cylinder an area the size of the piston head is acted upon by the hydraulic fluid 00 0and during the outward stroke the area reacted upon by the fluid is the annulus defined by the piston head perimeter o and the ram perimeter, and thus for a given flow rate of supply of fluid the speed of advance differs from the speed of withdrawal, leading to different rates of deflection depending upon whether the ram is on the inward or outward stroke.

o a Figure 12 shows a system in which two cylinders are utilised to provide egualisation of the deflection speed in each direction, and also to provide a failsafe system. Two hydraulic cylinders 43 and 44 are mounted on opposite sides of the flap 2, in a symmetrical arrangement, and hose lines 45 and 46 represent respectively the pump and tank lines for the hydraulic fluid. The pump line divides into branches 47 and 48 and each branch continuos to a valve 49.

Branch 47 then connect to the annulus side of hydraulic cylinder 43 and branch 48 connects to the full bore side of hydraulic cylinder 44. The tank line 46 divides similarly into branches 50 and 51 which connect respectively via more

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i 8 valves 9 to the full bore side of hydraulic cylinder 43 and the annulus side of hydraulic cylinder 44.

Thus in operation when a spool valve 52 is set to permit pressure flow the pressure is supplied to the full bore of cylinder 44 and the annulus of cylinder 43, while hydraulic fluid escapes to the tank from the full bore of cylinder 43 and the annulus of cylinder 44. This moves the flap in a given direction with a speed determined by the annulus/full bore combination and a reversal of the flow directions moves the flap in the opposite direction with the same speed.

The valves 49 are flow sensitive devices and are designed to shut if flow exceeds a predetermined rate, such as would occur if a flexible hose burst. Upon shut down of such a valve 49, the flap movement continues, but at reduced speed powered only through the other cylinder.

The two cylinders may be displaced from one another vertically. For example, in a structure as shown in Figure 13 one cylinder (not shown) may be placed at one hinge assembly indicated generally at 53, and the other at a different hinge assembly. More than one pair may be provided either in an alternate arrangement or in pairs on the hinge assemblies. During deflection the loads are shared by the cylinders in the ratio of their full bore and annulus areas, the imbalance being distributed by the torsional stiffness of the flap.

The apparatus has been described in the context of a multi-element wingsail, however a similar arrangement could be used for deflecting other aerofoil members of a wingsail system, for example a control device such as a tail vane as shown in Figure 2.

Claims

2. A self trimming wingsail assembly comprising a thrust wing having a symmetrical upright leading aerofoil having a leading edge and a trailing edge and a symmetrical upright trailing aerofoil having a leading edge and a trailing edge, the leading edge of the trailing aerofoil being positioned closely behind the trailing edge of the leading aerofoil, i 10 means for mounting the trailing aerofoil for pivoting movement about an upright axis in the plane of symmetry of the leading aerofoil from an aligned position in which the trailing aerofoil is coplanar with the leading aerofoil to positions to each side of and angularly displaced from said aligned position, and a symmetrical tail aerofoil mounted Son a boom extending from the leading aerofoil, the assembly being freely rotatable about an upright axis and the tail aerofoil being capable of deflection to each side of an aligned position parallel with the leading aerofoil in order to rotate the aerofoil assembly about said upright axis to a corresponding angle of attack to the wind, and means for deflecting the tail aerofoil comprising at least one pair of double-acting fluid operated cylinders, each cylinder having a piston separating an annulus side of the cylinder through which a piston rod passes from a full bore side of the cylinder, the cylinders being connected so that the tail aerofoil is moved by co-operative action of a first one of said pair of cylinders on an extending stroke and a second one of said pair of cylinders on a contracting stroke and in which fluid flow is simultaneously to the annulus side of one cylinder of the pair and to the full bore side of the other cylinder of the pair.
3. A wingsail assembly according to claim 1 or claim 2 in which the full bore side of each cylinder of the pair is interconnected to the annulus side of the other cylinder of Sthe pair.
4. A wingsail assembly according to any preceding claim in which the cylinders are connected so that on the exterding stroke fluid is conducted into the full bore side of the cylinder. 11 A wingsail assembly according to any preceding claim comprising at least two pairs of cylinders, one pair connected so that on the extending stroke fluid is conducted into the full bore side of th cylinders and the second pair being connected so that on the extending stroke fluid is conducted into the annulus side of the cylinders.
6. A wingsail assembly according to any preceding claim in which the cylinders are individually disposed on respective ones of a plurality of hinges interconnecting the aerofoils moved by the cylinders and the cylinders are alternatively arranged so that adjacent cylinders operate on different ones of said extending and contracting strokes for a given direction of movement of the moving aerofoil.
7. A wingsail assembly snbstantially as hereinbefore described with reference to Figure 12 of the accompanying drawings. Dated This 14 day of December 1988. JOHN GRAHAM WALKER and JEAN MARGARET WALKER Patent Attorneys for the Applicants: F.B. RICE CO. i.