AU602621B2 - Wingsail deflection - Google Patents

Description

r ;11--1 i COMMONWEALTH OF AUSTRALIA Patent Act 1952 602621 COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number Lodged t S.

'S.

,r e 0 Complete Specification Lodged Accepted Published Priority: Related Art A S Name of Applicant

WALKER

Address of Applicant Actual Inventor S Address for Service JOHN GRAHAM WALKER and JEAN MARGARET both of Tipwell House, St. Mellion, Cornwall PL12 6RS, England JOHN GRAHAM WALKER F.B. RICE CO., Patent Attorneys, 28A Montague Street, BALMAIN. 2041.

Complete Specification for the invention entitled: "WINGSAIL DEFLECTION" The following statement is a full description of this invention including the best method of performing it known to Us:a, I I I F B. RICE CO PATENT ATTORNEYS Thisforinis,;uitableforanyty a of Patent Application. No legalisation required, la- This invention relates to wingsail aerofoils.

aerofoils, and especially The wingsail, systems with which the present invention is concerned are generally of the self setting type that are mounted freely for rot4ion about an upright axis, the wingsail system comprising one or more mult.1-element thrust wings 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 tao airflow is considerable, and must be resisted if the cambered configuration is to be maintained. If a hydraulic ram is used to drive the flap and maintain its position, this necessitates use of 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 f lap is fully deflected, but the hydraulic raiii 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 n 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.

The present invention is directed towards a method of assisting the flap to reach operating deflection.

Accordingly the present invention provides a method of operating a self-trimming sal.1set comprising a thrust wing having a leading airfoil and a trailing airfoil flap and a 2 trimming tail airfoil, the method comprising adjusting the angle between the tail and the leading airfoil to rotate the sailset towards a position in which the moment opposing a movement of the flap in a particular direction is reduced, moving the flap in said particular direction, and then readjusting the tail to trim the sailset to the desired angle of attack.

The forces may be reversed tending to aid movement of the 10 flap in the particular direction.

0O The invention also relates to a control system for moving the flap of the self-trimming rig, and in this aspect 0* provides a control system for a self-trimming sailset 15 comprising at least one thrust wing each having a leading 00 airfoil and a trailing airfoil flap, and a trimming tail airfoil, the control system comprising means for adjusting the angle between the tail and the leading airfoil to rotate the sailset towards a position in which the forces opposing a movement of the flap in a particular direction are reduced, means for moving the flap in said direction and means for subsequently readjusting the tail to trim the a sailset to the desired angle of attack.

25 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 purpose arrangements capable of adopting mirror image configurations are favoured.

The invention is now described by way of example with reference to the accompanying drawings in which: i _i i- 3 Figure 1 is a schematic diagram of a two section wigsail showing the hinge moment; Figure 2 rig with is a schematic diagram of a self trimming wingsail all aerofoils aligned; Figre 3 is a diagram of a hydraulitaly operated pinlock; S. S 5505 F 5

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F 5 S S 5 Figures 10 wingsail Figure 7 rig with 15 Figure 8 camber; 4 to 6 are a schematic diagrams of a self trix.ming rig undergoing flap deflection; is a schematic diagram of a self trimming wingsail a tail vane set for trimming; is a flow diagram for a control system for changing

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S5 Figure 9 is a schematic plan view of a two element wingsail in the symmetrical position; Figure 10 and 11 are schematic plan views of the wingsail of Figure 9 in cambered configurations; Figure 12 is a schematic plan view of a hydraulic system according to the invention, and Figure 13 is a perspective view of the wingsail assembly of Figure 9.

-4 fEaferring to Figure 1 a wingsail comprising a lea&aing aerofoil 1 and a trailing aerofoil flap 2 is shown with theN 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 0:00 into the hinge in order to relieve the stress on the as** 10 hydraulic system during tacking, but never-the-less the flap moving system is still subject to stress when moving ego :the flap in a strong airstream, and unless it is very heavy :~e(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 ope~rating a self *0*60 trimming wingsail system has been devised in. which the trimming system is operated in order to reduce the movement 20 opposing moment about the flap hinges. A self -trimring.

wingsail is one in which a control aerofoil, preferably in the form of a tail vane mounted on a boom is used to trim o 0 the main aerofoil, the desired angle of attack being set by the relative deflection of the tail vane which then trims 23 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 wings. This will rotate the main aerofoil.

so that the resistive force on the flap is much reduced, or even eliminated and replaced by a force assisting deflection. The flap is then deflected, locked and the tail vane readjusted to trim to the desired angle of attack.

I 5 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 S 10 wings, as shown in Figure 2 with hydraulic ram 5 mounted on 00, 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 S 15 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 1 to the position shown in Figure 6 is now aided by the wind, and upon achieving maxi. .m 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.

S* The same procedure can be repeated in reverse for the other 25 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 sinplified 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 int%-rogation 'is flap lock out' -6followed by 'move flap' for the respective affirmative response.

The fluid cylinders may be operated as described hereinafter which is the subject of our co-pending application No Referring now 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 Figures 10 and 11, the deflection being controlled by a Ssystem incorporating at least one fluid cylinder, such as a hydraulic ram. A problem with using a hydraulic ram is that see,, during the inward stroke of the ram into the cylinder an 15 area the size of the piston head is acted upon by the hydraulic fluid anid during the outward stroke the area reacted upon by the fluid is the annulus defined by the piston head perimeter 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.

Figure 12 shows a system in which two cylinders are utilised 25 to provide equalisation 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 continues to a valve 49.

Branch 47 then connect to the annulus side of hydraulic cyliner 43 and branch 48 connects to the full bore side of hydraulic cylinder 44. The tank linu 46 divides similarly into branches 50 and 51 which connect respectively via more i. -1 7 valves 9 to the full bore side of hydraulic cyliner 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 determinder 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 pipe burst. Upon shut down of a valve 49, the flap movement continues, but at reduced speed powered only through the other cylinder.

9 44 S' The two cylinders may be displaced from one another vertically. For example, in a structure as shown in Figure 2 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 25 the hinge assembles. 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 memebers of a wingsail system, for example a control device such as a tail vane as shown in Figure 2.

Claims (5)

1. A method of operating a self-trimming sailset comprising a thrust wing having a leading airfoil and a trailing airfoil flap and a trimming tail airfoil, the method comprising adjusting the angle between the tail and the leading airfoil to rotate the sailset towards a position in which the moment opposing a movement of the flap in a 10 particular direction is reduced, moving the flap in said particular direction, and then readjusting the tail to trim the sailset to the desired angle of attack. ar S2. A method according to claim 1 wherein the flap is locked 15 in position after movement in said direction.

3. A method according to claim 1 or claim 2 in which the 0 .4 tail is adjusted to its maximum deflection in one direction and the flap is deflected in the same direction. A method according to claim 2 or claim 3 in which the .M movement of the tail and flap are commenced simultaneously. *f q, .o 25 5. A control system for a self-trJnming sailset comprising at least one thrust wing each having a leading airfoil and a trailing airfoil flap, and a single trimming tail airfoil, the control system comprising means for adjusting the angle between the tail and the leading airfoil to rotate the sailset tovrds a position in which the forces opposing a movement of the flap in a particular direction are reduced, means for moving the flap in said direction, and means for subsequently readjusting the tail to trim the sailset to the desired angle of attack. i 6 I i; I, I *rua -9-

6. A control system according to claim 5 in which the flap is locked in position after movement in said direction.

7. A control system for a self-trimming sailset comprising at least one thrust wing each having a leading airfoil and a trailing airfoi flap, and a single trimming tail airfoil, the control system comprising means for adjusting the angle between the tail and the leading airfoil to rotate the sailset toward a position in which the forces opposing a movement of the flap in a particular direction are reversed and means for subsequently readjusting the tail to trim the sailset to the desired angle of attack.

8. A method of operating a self-trimming sailset substantially as hereinbefore described with reference to Figures 4 to 8 of the accompanying drawings. C S-) ,f 6 DATED this 14 day of December 1988. JOHN GRAHAM WALKER ind JEAN MARGARET WALKER Patent Attorneys for the Applicants: F.B. RICE COMPANY