CA2111239A1 - Wind powered or assisted hydrofoil craft - Google Patents

Abstract

2111239 9222396 PCTABS00018 The present invention relates to wind powered or assisted craft, particularly hydrofoil craft, which are capable of travelling considerably faster than wind speed over a wide range of wind speeds and directions. The invention has application from single person leisure and sports craft through to large commercial cargo and passenger vessels, although certain aspects of the invention will find application to wind powered or assisted craft or vehicles for use on land and to hydrofoil supported craft in general. Whilst in the case of smaller craft, wind power may provide the sole means of propulsion, in the case of larger craft the provision of auxiliary power sources is likely, as an aid to low-speed man uvring and operation in unfavourable wind conditions. Heavier craft may well require the assistance of such power sources to get through the ''resistance hump'' which is characteristic of hydrofoil craft.

Description

W092/22396 PCTJEP92/01~2 - ~Z1112~9 WIND POWE~ED OR ASSISTED ~YDROFOIL C~AFT

Field of the in~ention The present invention relates to wind powered or assis-ted craft, particularly hydrofoil craft, which are ca-pable of~travelling considerably faster than wind speed over a wide range of wind speeds and directions. The invention has~application from single person leisure and sports craft through to large commercial cargo and passenger~vessels, although certain aspects of the in-vention will~find; application to wind powered or assis-10 :ted craft or:vehicles for use~on land and to hydrofoilsupported:;craft in general.
WhiIst in~ the case of smaller craft, wînd power may provide~the~ sole means of propulsiQn~ in the case of ;larger^~craft the provision of auxiliary power sources : ;lS~:is:likely,~ as~an~aid~to low-speed`manoeuvring and ope-ration~in~ un~avourable wind conditions. Heavier cra~
mày~well~require~the assistance~:of~:such power sources to~get~through~he 'resistance~hump'~which is charaate-;ri`stic of~;hydrofoil~cra~ft. ` :
20~ De~cr~iption:of:the Prior Art Wind~powered;~craft;of current~art have not fouhd favour r than~for le~lsure~or sporting~purposes~due to li-;c~ u:~ ~ it` ` pèr ~ ~and^ithè~c ~ o controlling the 25`~:of~heel~ing:and~ of;~going`to ~windward, and::~the require-ment: for relatively high ~wind: speeds:to~ achieve any :: real performance.:~Aerofoil sa~ils hàve~been fitted to a very limited~ number of commercial craft as auxiliary ;propulsion~ devices to reduce~fuel~consumpti~on and im-30 :~prove~roll`~damping.
A small~number of racing and~ cruising~craft have utili-sed ~aerofoil wings in the past'~but ~:invariably these have-been:designed for use on~ conventional hulls and effort has:~:been concentrated :either on attaining`~high lift coefficient or on easy handling~ Neither case re-SUBSTITUTE SHEET

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2 1 1 1 2 3 9 su}ts in the high ratio of lift to drag required to sail at high ratios of boat speed to wind speed. Also the majority of designs have required ~anual setting in the ~ame way as a conventional sail ~t as an aerofoil section is generally much less tolerant to changes in inciden~e :constant attention is re~uired if adequate performance is to be achieved. A small number of de-signs havs appeared using sel-trimming wing sets~ ~ut thes also have generally been adapted for conventional : ~10 hulls rather than being optimised for the higher :; : speeds attainable by the use of well designed hydro-~oils. ~:
Whilst a number of Aydrofoil suppor~ed wind-driven craft ha~e; appeared in recent years few, if any, have 15::fulfilled the expectations of their designers. There are a number of~reasons for this situation.
The~majority o~designs have employed a triangular foil plan with two surface piercing or fully ~ubmerged foils situated approximately amidships and spaced either side 20~ of the longitudinal axis of the craft and a third in-verted JT' foil~at:the rear of the craft. This arrange-nt res~lts~.in~a short foiI-base relative to th~ loges ;of; the craft ~w~hich results in ~excessive ~ariation of foil~loading ~wi~h dlffering wind~and speed conditions.
2~5~ Also~because the:rear foiI has to provide lift in ei-ther sense but~requires a~ change in~craft attitude to change its :angle of attack it has to be long~ resulting ~' in a large wetted area and excessive flexure when sub-: jected to~steering loads.
~ : 30 In many cases surface piercing foils have been used ; ~which suffer~from high drag, cannot be reliably used to . provide the negative lift required at speed on the windward foil, and are subject to considexable changes in angle :o~ attack due to wave orbital motion and chan-ges in cra~t attitude which renders them erratic.

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In cases where fully submerged foils have been applied generally these have been designed to provide upwards lift only, or, at best only limited amount of downwards lift due to the difficulty in arranging for sensor sys-S tem~ to cope with the moment reversal involved. In cer-tain cases such foils have been designed for downwards only lift which limits their use to a specified tack.
Also, previous designs using mechanical surface sbnsor systems have used relatively high loads on the planing or buoyant body used ~o sense the water surface to re-duce the chance of moment reversal with a consequencP
that these bodies have been relatively large dimensio-ned~and as they operate at a low ratio of lift to drag ;the~performance of the foil sy~tem as a whole has been : 15 poor. Whilst at~empts have made to improve the perfor-mance o~ a *oil in isolation in wave an~ chop condi-tions these have not resu1ted in the overall drag re-ductio~expected due to this effect.
ther~ma~or problem with virtually all foil craft has :20~;:been~the~;difficu1ty of retracting them satisfactorily :for 1aunching,~mooring and road:transpor~ and this fac-tor; is.:di~ficult:to resolve~:dua :to`-~the high imposed f~ 5~;5~ ~oad~.. Also.~virtually all~ hydrofoil~-craft have been xcessive1y~ide and.as hydrofoils `or~their associated 25~;sen ors ~have:tended to extend beyond the contours of the~craft ~there is ~:onsiderable~risk of ~nagging on other craftl~ buoys, etc, ..~
Prior art -foil supported sailing: cra~t have generally - been based~:on conventional hulI ~e igns such that hy-drofoil p~ivots: and attachments have :been placed much ~:~higher than ideal above the water line which has resul-ted in unnecessarily high deflections seriously impai-ring hydrofoil performance. Additionally such hull forms generally perform poorly under the considerable - ~ 35 attitude changes which occur at around lift-off speed ~1 IR.C:TITI IT~: C~l=~T

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due to either fore or aft hydrofoils lifting before the other due to changes in foil loading, and this has made lifting off erratic.
When traYelling at high speeds, ana in particular at high ratios of boat speed to wing speed very high for-ces are generated and prior art designs have required external rigging to support these loads and this has considerably added to windage.
8ummary a~ obiective~ of the pre~ent invention The present invention overcomes many of these limita-tions and permits craft to be designed to operate at speeds hitherto unachievable, ~xcept for very high powered racing craft operating on calm water, and to maintain such high speed under a wide range of wind and sea-state conditions. To achieve such performance requires exceptional aerodynamic and hydrodynamic cleannesg for which this present invention provides. In artiGular ~ the use of fully subm~rged lift hydrofoils of high aspect~ ratio rather than surface piercing or 20~ planing hulls to~provide the required li~t reduces the hydrodynamic drag to the point where the lift coe~fi-cient r~quired~of the-driYe producing aerofoil wing is relatively-modest such-tha it~is able to operate at a very much higher ratio o~-lift to drag-than ha~ hither-as: to been possible.he power required to drive even efficiently designed hydrofoil or planing powered craft at such speeds is very high indeed and would imply unacceptable levels of : fuel consumptlon and pollution for any practical appli-cation. Fur~hermore, considerable lo~es can be expec-ted in transmitting such high powers at high speed~.
The present:invention allows such power to be derived, or largely ~derived from wind energy with a consequent reduction in pollution, operating costs, and maintenan-ce.

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~ 92/22396 PCT/EP92/01~2 The efficient aerofoil wing of the present invention can generate large amounts of lift even at moderate angles of attack, and, furthermore, the lift ~enerated is proportional to the square of vel~ity which is al~o the rate at which drag increases. Thus a craft of this type can generate a fairly constant accelerating force over a wide speed range relative to wind speed and becau~e the rolling of pitching moments is counteractedby aerodynami¢ or hydrodynamic forc~s the performance is limited by structural considerations rather than by the maximum righting moment which is limited by weight and geometry for form or moving ballast stabilised sai-ling craft. Additionally the self-trimming wings of the invention allow the wings :to be placed to the rear of 15:~the~craft allowing the crew an unhamperad forward view and also: allow~the use of more generally used controls than~is pos~ible in other wind powered craft.
Thus, according t o a f irst independent aspect of the present:invention a wind powered or assisted hydrofoil 20~ craft co~prises a hull or fuselage with an upward~ ex-tending wing which may be pivoted about a ~enerally v2rtical~ axis~to:maintain a controlled angle o~ attack ;~ elatiye:.. ~to:.the~apparent~:~wind~to: produce forward or réarward;:~dri~ he- surface~:~wept by.~he ~ower end of S~ the~upward~extending wing as it sweeps around i s gene-rally v~rtical axis may be ~ plane sur~ace normal :to ~ the wing pivotal axis and in this case the lower end of :é ~ the wing can rotate at a small vertical distance above : this plane whioh, as a consequence acts~as an effec~ive : 30 end plate whlch, in conjunction with :its prefsrred close proximity to the water surface, serves to greatly increase:~the :effective aspect:ratio;of the wing. Two : generally vertical downward extending ~urface~piercing hydro~oils which are spaced laterally one from another -~ 35 about the craft's longitudinal axis may act as end ,~

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plates for an aerodynamically shaped hull and act as keels. These hydrofoils are preferably placed towards the rear of the craft. A downward extending surface-piercing hydrofoil pivoted about a ,generally vertical : 5 axis or provided with a generally vertically pivoted : : flap and spaced at a distance along the craft's longi-tudinal axi;s: from the laterally spaced hydrofoils may ~ : be provided~for steering means and may preferabl~ be, positioned ~towards ~the front of the craft. At normal 0 operating speeds the hull or fuselage is maintained at a~height above the water surface by the hydrodynamic lift produced~by the generally horizontal hydrc~oils. A
generally horizontal: hydrofoil, which may be surface-:piercing or~fully submerged, may be~mounted at the lo-15 :~wer end ~of the~ vertically piv~ted: hydrofoil to providevertical~ ift:~to:support the ~required proportion of the weight of~'the ~craft and offset the pitching moment, etc.~Further~horiz~ontal or horizontally inclined hydro-:foils:moùnted:~:to~ th~ lower :ends~of the laterally ~paced 20~ ~ertical~ hydrofoils and:which~are preferably provided with means~ for~:controlling their angle of attack pro-,vide~the~vertical~lift ~to overcome the~proportion of ,6,~ the~weight~Qf~the:~craft not~provided~:by'~'the f:irst hori-.zontal hydrofoil and to offset~ any~`roll-moment etc. The ",~25,~ hydrofoils~together with-any~mechanism to control them sbould preferably be contained within the plan contour of the cra~t.~The hydrofoils~are~preferably retractable for launching:and for operation in shallow water and may remain~-sufficiently immersed~:for the craft to 30 ~operate~:at restricted performance in: the retracted ~ta-te. Landing wheels may be attached ~a the hydrofoils or : their mechanisms for launching such that they are auto-;~atically-~lowered when the hydrofoils are retracted.
Lar~er, detachable wheels may be fitted for use on land which may be interchangeable with skids for use ~n ice SUBSTITUTE SHEET

V~92/22396 PCT/EP92/nl~2 and the wing control system may be adapted to prevent capsiæe in this case.
The wing may alternatively be fixed to a planar or do-med disk pivoted about a generally ~e~tical axis. Such a configuration eliminates the gap between the wing and the hull resulting in increased aerodynamic efficiency, and usually increases the structural strength and stiffness;of the assembly.
The upwards extending wing may beneficially be placed towards the rear of the craft. This configuration allows the cockpit to be placed towards the front of the craft giving the crew unhampered visibility whilst also permitting the wing to be positioned as close as .
possible to~ the; water surface minimizing the rolling 15 ~ moment and;~ maximizing the increase in effective aspect ratis resulting~from the mirror-imag~ effect.
Whereas:mention is made above of a single vertical wing, the~principle will equally apply to craft provi-ded: with~multiple vertical or upwards extending wings, 20~ the~pro~ision~of which may be desirable to :diminich the : moments about ~he:roll and pitch axis of the ~raft, or to~reduce.;~he~ size~of-any indivldual wing. In the case j,f~ rwherein.multip~le~wings are provided~each ~ay be pivoted abo:ut::-its~iown ~generally~vertical~i-axis,~i`all ~he wings 25~ ~ay be pivoted~about a single~ax;is, or~groups of wings may be pivoted~ab~ut generaIly vertical:axes.
` Whilst the win~s will normally be rigid or semi-rigid the use of fabric wings with conventional or wing-type ma~ts is~perfectly envisageable for lower speeds.
3~ Since a oraft of this nature will normally operate at speeds well below those a~ which compressibility :e~fects become significant the wings may have a relati-vely thick section which will normally enable the wing to be self-supporting without the requirement for stays SUBSTITUTE SHEE~

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or riggin~, the provision of which would add considera-bly ~o drag.
The angle of attack of any upwards extending pivoted wing may conveniently be adjusted by ad~usting the angle of attack of a small control aerofoil pivoted about an arm or arms extending rearwards from the wing such that the;control aerofoil provides a moment about :the pivot axis of t~e wing which overcomes the mQ~ent due to the lift generated by the wing, the whole being : 10 free to weathercock about the pivot axis of the wing.
Where more~:than~ one drive producing pivoted wing i5 provided~each wing or group of wings arranged to pivot about~ a single~ axis is preferably provided with a control aerofoil to ~ontrol its angle of attack.
lS~ :The~hull~provides~the~ buoyancy and ~stability required to~support~ the craft~ before it lifts o~to its hydro-foils and:generally links the other elements of the :oraft:and~transmits or absorbs the forces they generate and:~to~th~is end it~is preferably made up of aerody.~amic ~"~ 20~;-secSions~ which~ provide stiffness and reduce drag. The lower~surPace~ of the hull is preferably canfigured to ;présent three,~'slender:;~hydrodynamic~.lifting surfaces the ,r~r~ ":cen s of~;lift~af -~ ich~c esp ~ d~ approximatel ".~the~ cen~res~'of~ 1ift. of: the~;three-~generally horixontal 25~ ~ rofoils~and~:which~ are of h:igher~aspect ratio than would normally :~be possible~far ~a planing sailcraft.
Their anglés`of attack can be~broadly optimised to aperate ;at maximum efficiency within the range craft attitudes~ anticipated prior ~to lift-off:.~ The forward '1i~ting: surface~ is preferably;;split into:~wo portions a~lowing ~a::central tunnel inta~which the forward hydro-oil aan~be retracted and rotated for: steering. This :, arrangement can be arranged to be-~extremely efficicent for the limited range of speeds prior to lift-off. Al-. , ~:35 ternatively the three lifting surfaces may be merged .C I I R.CTITI ITC ~ i~ ~ ---.

W092t223~6 PCT/EP92/01~2 into a single surface of moderate aspect ratio. With the preferred hydrofoil and wing configuration the hull may be generally delta shaped with the front of the delta broadened to protect the forward~ydrofoil and to provide the forward~hydrodynamic lifting surface and with the rea~ extended laterally to support the rear : ~: hydrof.oils: and: to provide the two rear hydrodynamic: lifting surfaces which beneficially may be extended by : hydrofoil members:~and may serve to protect the rear ; : 10 hydrofoils and~ their control 'mechanisms and in this ::
case the~ downward axtending hydrofoiI members serve as end `plates further~enhancing the aerodynamic perfor-: mance of the~hull~ and wings. The hull may also be shaped such~that the two lateral hull extensions can be lS;~hinge~mounted:to the main hull such: that they can befolded inwards to=ether with their affi~ed hydrofoils ,~' "~ for~: transport~or~ torage allowing the width to be ap-:,proximately~:~hal~ed and allowing simple assembly. The above~delta~:shape~a~lso provides an e~fective ~end-plate 20~ for~the wings~;and~a smooth transit.ion between the hull and~wings.~The~:preferred~ rigid~wings of the: invention are;~,.relat~ively voluminous and the~ broad rear width of t ~ ,..del ~,'.ishape ~e~its~ the~ ision,,of a~:hatch or 'r ~5~ op,ening~.`u ~ ~ ~ e~w'ngs;,c n~ be,iin~erted into the 25~ hu,11~for~,tran~sport.~or.:,storage.~
The~:rol1ing~moment produced by~a~hydrofoil of the high aspect~ratio~;required for efficient operation is con i-derable and.this~would normally require that the moment resisting~hydrofoil~s should be placed~:at a:large ' ~lat~ral dIstance one to~the~other.:Th~is would require a very wide~craft:and a support stru~t~re which would add con iderable~weight and windage. Additionally the con-trol aerofoil described herein above is ~onYentionally ,placed behind the main drive producing wing or wings :
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211123!3 and operates in their wake resulting in excessive drag and erratic results.
Thus according to a second independent aspect of the present invention, a wind powered ,OE assisted craft comprises at least one upwardly extending wing arranged to have the high effective aspect ratio required for efficiency but such that the centre of effort is rela-tiYely low ; thus limiting the rolling and pitching moments created. The wing arrangement envisaged can be designed for both a high ratio of lift to drag and an advantageous dis~ribution of lift in the various condi-tions of wind ~hear which may be encountered.
In its basic form a wing according to this invention is generally tapered along its length such that the chord ' 15 at it~ root is greater than the chord at the wingtip such that;the fractional chord of the flap ,at its base is greater than the fractional chord at its tip and which has at least one trailing edge flap which is ta-pered to~a~greater~ extent than the wing such that the 20~;fracti,onal~ chord of the flap at its base is greater than the~f'ractional chord at its tip. This arrangement not' only-~provides a centre of~a~ea which i~ belvw the mid span~of;~the`~wing but also'ldèpending~on the relative S extent-;o~'flap`'déflection'-~and~wind~ éar'can allow the 2S~local lift ~coefficient to be~highér at the base of the w`ing than~at ,its tip, and is~particularly effecti~e in the case that the wing is sea;led~closely to the hull ' and to the water-plane at its lower end. This variation in local~lift~ coefficient ~urther depresses the height of the ~entre of effort. The wing may additionally have - a tip member pivoted such that it~can operate at a ge-nerally different angle of attack to the main wing;
the addition of such a *ip is particularly advantageous for operation in conditions where the apparent wind is ~ 35 considerably sheared such as occurs when broad : : : :
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~092J~2396 PCT/EP92/01~2 rsaching. In the case that the wing is pivoted about a generally vertical axis or is a member of a group of wings so pivoted, the pivoted tip may be advantageously swept forwards or rearwards such t~a~ its centre of effort is at a distance from the pivot axis for rota-tion of the ~wings such that it stabilises the wing : about its pivot axis and such that by changing its ' : angle of attack the angle of at~ack of the win~ or ~: group of wings~is; also changed. This arra~gement is much more efficient than the provision of a con~rol aerofoil arranged~ generally behind the main wing or : wings as it tends to decrease rather than increase induced drag and operates in better airflow conditions rendering~it~more sensitive. The main wing may be 15:~ generally~boomerang shaped such~that the lower part of the~ wing;~io generally swept forwards whilst the upper ,part~of the~wing~:~is~generally swept backwards or vice-ver~a. This~::arrangement is particularly efficient in ;the~case~ where~the pivoted tip~ section is used to 20~ controI a~ wing or group of freely:pivoted wings as it ,tends to:~increase the restoring moment generated by the wlng f or ~any~ .:change in the angle~:of attack.
",~ The~.. ef~iciency~:of^~the~-;wing~ may be~further~-increased by s~ ",,,~f,~ ' ,.",, ~ isting~it~.~alonq~-its~'length~u ~ ~hatC;it adopts the , 25:~same~angle~ 0f~attack~:~as~ the tip section at `'its upper end.~ A similar~effect may also be achieved by dividing the wing ~into~sections along:its ~Iength and rotating each section to differing extents.
In an arrangement with two or~more wings each wing will :30 tend to produce different amounts of li~t~due to vorti-:city and this~may be countered by:de$1ecting the flaps and/or the pivoted tips of di~ferent wings to differi~g ex*ents.~This~ is particularly:the:case where two or a leeward wing~stalls before a windward wing the : : 35 wingset could become unstable.
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In any arrangement where two wings are arranged to pi-vot about a common generally vertical axis they may preferably be arranged such that they splay outward~
one to another such that their lower e~d~ are more clo-sely spaced than their upper ends. This arrangementresults in a particularly favorable aerodynamic perfor-mance and reduces the inertia of the entity which improves dynamic performance. Additionally the pivoted wing tips of~ the wings of this arrangement may be splayed inwards~at their upper ends which further -~ ~ reduces the inertia and reduces the inscribed radius.
In the case~where the wing control foil constitutes an upward extension to the m~in wing, the control moment required to~ rotate the wing tip may conveniently be 15;~arranged to~partially or completely balance the control mo~ent required to deflect the flap or flaps. The flaps of~two or more~wings may be arranged to be deflec~ed by a single~actùator whilst the tips mny be deflected by a linkàge~ situated at the upper end o~ the wings such 20`~ that a gLven fl~p deflection of any wing results in a corresponding~rotation of the tip. In a favoured arran-gement,~ the,~ratio between the deflection of the flap of .cG ~ any~ wing~and~the~r ~ ation of~ s-tip may ~be varied by the~provision~of an~actuator-which varies~said linkage.
2~5~-- A~wing-~may~be-configurated with two or more~flap~ in which case~said flaps may be arrange~ to be actuated differentially~;to further modify the lift distribution along the wing.
As herein aboYe~described hydrofoil supported cra~t of ;30~ prior art~have~ been designed for vertical lift compo-nents in~one~sense only whereas hydrofoi1s for high speed wind powered craft require that ~he windward foil provide a~ downwards lift component which~needs to be provided b~ the lee hydrofoil the craft weight normally having only a marginal effect. For a ~raft designed to , SUBSTITlJTE SHEET

W092/~96 PCT/EP92/01~2 - 211i239 navigat~ on either tack any laterally disposed hydro-foil will consequently need to be arrangad such that it can provide similar amounts of vertical lift in either sense. ~_ Thus according to a third independent aspect of the present invention a wind powered or assisted hydrofoil : ~ craft has at least one hydrofoil comprising a generally vertical surface-piercing section, a generally horizontal normally submerged section and a generally horizonta1 pivot axis arranged such that the angle of attack:of the generally horizontal section may be ad-justed to ~a~ similar extent in both positive and nega-tive senses wherein the generally horizontal section may be adjusted to a similar extent in both positive 15: and negatiYe~ senses wherein the generally horizontal sectian is~; pivotally attached to the lower end o~ the enerally ~vertical:section and wherein the hydrofoil is ~ounted~such~as to;prevent~any reversal in the scnse of the~ moment~ resulting from the ~1ift and drag forces 20~ cr~ated~by said hydrofoil;abou~ said pivot axis from being transmitted to:any actuator or surface~ sensing :means which con~rol its motion.
` In~theory ~or;this~c voted~:~bo~ut~:its.centre-.of li~t-~and: as~uming this to be 25~ coincident~with th2;centre~0f:drag no dîsturbing:moment would be~ created by the:hydrofoil ~section about said pivot. However in::p~actice:~the~lift centre is not ~sta-~: : ; tic and manufacturing tolerances in positioning the ~: :1 : i ` ~ :
; axis and manufacturing the foi1~sèct~ons ~are finite so30: that some moment will be~created ~which will vary ap-pr~ximately linear1y with the ~angle of attack and qu~-;: dratica11y~with speed. Thus:a~simple spring bias is notappropri;ate and some provision must be made to ensure ~:-` that the moment created: acts:aIways in the same sense.
For the case in question the generally horizontal ~: ~ SIIR.~TITI ITF c~ Fr ` ~ .

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hydrofoil may be pivoted about an axis arranged sligh-tly in front of its centre of lift and may further com-prise at least one downwards projecting fin of such dimension that for forward mo~ion thç'-sum of the moment created by the vertical lift component generated by said hydrofoil section together with the drag moment created by the fin about the pivot axis of said hydro-: foil section always acts in the same.sense whether said vertical lift:component acts in an upwards or downwards .` :. 10 sense. The generally horizontal foil section may bene-~ ;:ficially be arranged with dihedral.
~ -;: The herein ~ aboYe described arrangement suffers from some of the disadvantages of most prior art design in : that undesirable flow characteristics around the arti-culation~of :the: generally horizontal hydrofoil section are~:diffi:c~lt;~:~to mitigate. Furthermore, the hydrofoil e~tions will~normally be small~in section and very :thin~ and~ will ~consequently ne d to ~be thick walled or even solid:~to: prevent excessi~e def:lections. As a re-2~0~ sult~there~will~:be::1ittle room to:accommodate hydrauliclines, control~rods, actuators, and the like within the hydrofoil~ection.~
hus~ in~ an~ alternative arran~ement:'`the 'generally hori-zontal`~ ~,xis~is~;arranged such t~at'it~ s above the water 25~,1éYel ;for'~normal~foil-borne~opêration, In~this arrange-ment the~generally horizontal section may be `fixed to the~ generally~vertical section which~ consid~rably redu-ces the problem of assurinq a smooth flow pattern and furthermore~no pivots, actua:~oræ, control lines or the ; 30 1ike need~ to be contained within the hydrofoil itself but instead an be incorporated within the body of the :craft. A hydrofoil produced in this manner is si~ple, lightweight and':strong as well as being:hyd~odynamical ly efficient. The disadvantage :of this arrangement is ; 35 that the moment of the lift and drag forces about the ~, ~

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pivot axis vary considerably with the angle of attack : and the immersion depth etc. and furthermore it is nor-: mally impossible to prevent a reversal of the moment except for small reversals of the desi~n sense of lift.
Thus according to a fourth independent aspect of the present invention a wind powered or assisted hydrofoil craft has at least one hydrofoil comprising a generally vertical surface-piercing section a generally hori~zon-tal normally:~:submerged section and a generally horizon-tal pivot~ax~is~arranged such that the angle of attackof the generally horizontal section may be adjusted to ~` ~ a similar~ eYtent in both positive and negative senses ; ~ wherein the generally horizontal pivot axis is arranged such tha~t~it~:~is above the~water :surface for normal 15:~foil-borne~:operation such~ that both the generally ver-tical and~the~generally horizontal hydrofoil sections rotate~about:~the~pivo~ axis -as~a~unity and wherèin the hy:drofoil:-is~mounted such as to pr~vent any reversal in the~sensé~ of~;~the~ mo ent resulting~from the lift and 20~drag~forces~;;created:by ~the~ hydrofoil:about said pivot axis~from~being~transmitted to~any actuator or surface 8,ensing~mea ~ :control ~it8 m ~ ion:. ~ e mounting ~; ~ ang ,~mày~ ~ eferab ~ alæo::~inol ~ e means whe eby ariations~'n~sàid~:m e ~ ~are re ~ ced~
2;5~ The ~hydrofoil~mounting may~be~ arranged such that the generally~ horizontal ~pivot::axis is largely uncons-trained for translational movement in a generally ver-tical sense:and such that the verti~al lift component `:generated~by~sAid hydrofoil::~is largely resisted by part 30 ~of the craft which is translationa}ly mobi}e in a gene-:rally horizontal fore and aft~ se~se relative to said` pivot axis such as to prevent~said moment reversal and limit vAriations in such moment.
mAjor -difficulty in pivotinq:any h~drofoil other than : : 35 generally :along its axis is that: the forces which need ~ : ~

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to be restrained tend to be very high and it is diffi-: cult to avoid stress concentrations. Additionally, for any such hydrofoil which is controlled by mechanical surface sensing means in particular~-it is essential to : 5 r2duce friction torque to a minimum to help avoid ex-cessive sensor loading.
Thus according :to a :fifth independent aspect of the ~; ~ present invention any hydrofoil craft comprises at : least one:hydrofoil pivoted about a generally horizon-lO: tal axis ~close to the static water line of the craft whi~ch compr~ses a generally horizontal section arranged such that::it provides additional lift during hull-borne operation~ and such that it~is above the water level for no~rmal~:foil-borne operation and which is arranged such 15~that said~pivot~:axis extends generally along its length and ~a downwards extending genera`lly vertical hydrofoil ` seation~:and a:~urther generally~vertical: hydrofoil sec-tion and :a~ further generally horizontal section which is~ fu1ly:~su~merged for normal operation, ~wherein the 20~herein~abové~hydrofoil may be generally~`~'C' shaped.
Further~ aspects of~ the invention relate to: the retrac-tion~of~ ~ ofoils:for docking:which~has~hitherto been '.5~ a -~problem.:~ A~hydrofoil:::described~ in~ the independent . aspè~ts~four~and,five descri~ed~a~ove~ay be~retracted 25~ y~;forwards~ or~ rearwards rotation about~:its :pi~otal axis;and~in;~the case where:;~the~angle of attack ;is con-trolled~by~an~ aatuator: said:actuator~:may preferably be used also ~or retraction. Alternatively a cable may be used~for ~retraction. This~type~ of hydrofoil is~prefera~
30~:~bly ~retraoted~such that the normally:generally horizon-tal section~ is well clear~:of the water surface to pre-vent exaessive ~drag or ~alternativaly a~ second pivot : axis may: be:- introduced close to the::junction between : the general:ly horizontal ~and the~ generally vertical sections and which is locked for normal ~foil-~orne ope-: ~ : :: :

l IRC:!TITI ITr RUI=I=T

~0g2/22396 PCT/~P92/01~2 ` 2111239 .. . . . .

ration ~ut which allows additional pivotal action for retraction such that the angle of attack of the gene-rally horizontal section remains sensibly constant. A
hydrofoil as described in the third'independent aspPct may have an additional pivot arranged close to the wa-ter line which is locked for normal operation but about :which the hydrofoil may be pivoted f~r retraction. If a - cable is used~for retraction in this case it may~also serve to lock and release pivotal motion about said additional pivot:axis.
One hazard; for~ hydrofoil craft of this nature is the potential for hign speed impact with floating debris : :: ;~such as: lo~s.`; Whilst the relatively slender leading edge o~:the:~hydrofoil will cut through minor debris 15:~provision of compliance in a:direction parallel to the longitudinal~axis of the-craft ~s necessary to prevent, or minimise,~s~ructural damage to the craft and exces-:sive accelerationæ which could restllt in injury to crew or~passengers. ~Thus by incorporating some compliance 2:0~ into the~ac~uator ~or any linkage~:connecting it to the hy~rofoil, the~hydrnfoil will; rotate about its pivot axI~ i f ~the.~:~f orce-acting:~on the~actuator or the linkage ,Sj~as~a~ ~resu ~ ~:of~ such~-- n- ' ct'~ rsuff iently :gre 5uch~:co~pliance~may be::provided`by: suc~'means as a 25~.spring or a~:pressure relief valve~or accumulator.
As~;herein~ above described,~mechanical surface sensor : means of prior art have had forward projecting mecha-nisms which have extended the;overall dimensions of the :craft and~hav~ been liable to~snag on other craft 30~étc.~.. Also, because they have extended a considerable way in front of the foi~l which they have controlled the : longitudinal foil-base as~a ~raction of craft length ~ ~ , :has been smaller than is desirable. They have also pre-:sented large surface areas which have tended to result in high drag, particularly in chop conditions.
~,, :

:~
: -:
~T~T~ ~T~ ~ IJ 1~ ~T

W092/22396 PCT/ER92/01 ~

- 2111239`

Thus according to a sixth independent aspect of the present invention any hydrofoil supported craft which comprises at least one hydrofoil which has a variable angle of attack and is preferably co~figurated to pro-vide similar amounts of vertical lift component in ei-ther the upwards or the downwards sense has an associa~
ted surface sensing means comprising two leading arms ~which are pivotally attached to some fixed or mobile : part of the cra~t towards their rear ends and which ~10 further comprises a trailing arm forming a downward ex-tension to~::said ~forward link. The: lower end of said : ` trailing link may form:a surface-piercing hydrofoil or may be pivotally attached to such a foil in which latter case said surface-piercing foil will be pivotal-: 15: ly attachèd~to the lower end of a second trailing arm which is~pivotally attached to the lower leading arm at its~ upper end.-~The said surface-piercing hydrofoil is configured~to:ride along the wa~er surface such as to :alter~the~angle of attack of its ~ssociated hydrofoil 20~ as it changes its attitude relative to the craft. The sur~ace sensing means so comprised is preferably contained:~within~the.contours.of the craft in plan pro-, ~",.',:,7~ `' jection ~for~ pro~ection ~and~.thet gain of ~the sub-system mprising:the-~surface sensor-means~:and its asæociated 25~ ~hydrofoil~:~is~preferably readily~adjustable and may be adjusted~by~altering the langth~of :said joining link.
Said hydrofoil together with said surface sensing means : is preferably:configured for low combined drag and said surface-piercing hydrofoil of the surface sensing means : 30 : is preferably of small area and the first trailing arm may be designed to cut through chop with low drag. The herein above described: surface sensing means may be linked to a~hydrofoil as~described in the fourth inde-::pendent aspect of this invention in which case a link may be pivotally attached to one of~ said leading arms SUBSTITUTE SHEE
ç~,,"",~.

~092/2239~. PCT/EP92/01~2 211i~39 at its upper end and to said generally horizontallypivoted hydrofoil at its lower end such that upward motion of said leading arm or arm~ causes an increase in the angle of attack of said hydro~oil and Yice-~er-: 5 sa. In ~his case the rearward pivot of the leading arm : to which said hydrofoil link is a~tached may be colli-: near with~ the pivotal axis for retraction of said hy-:drofoil such that the angle of a~tack of said hydrofoil i8 not m~aterially~changed on retraction.
: 10 The hérein~abové surface sensor means may also be cou-pled to~ a ~hydrofoil as herein above described in the :: fifth independent aspect of this invention in which case the lower leading arm will form a forward exten-sion of;~a~generally vertical hydrofoil section a~d the ~-"'~ ;15~ upper ~éading;arm~may include a generally downwards ex-:;;tending ~arm~ which :locates:in a track generally verti-"~ cally ;disposed~above ~r~below~'the~:~p`ivot axis of said hydrofoil~such:as~to support the vertical component of ft generàted~by ~aid foil in~either an upwards or a 20~ do~nwards~ sènse~and said surface~sensox means'is~arran-'ged~such~that~ the included~ angle: between the forward ;L~'~ ' ,' '``;~'," ~ ' d~of:~ e~ ~ er~:~le ~ ing~a ~:a' ~the oining l nk be~- :wéen ~he 'forwa ; ~ t~ the"'do ~ i ed~::effe't:of h - ~ e ' ated by the 25~: byclrofoil~-~about:~its pivotal~.axis~and the ~rertical com-ponent-~'of~lift'~ it generates~ always~pro~uces a~do ~ ard thrust on~said`~ surface-piercing hydrofoil~ of the s~r-face sensing~ means.~The said~upper~ leading a ~ may be pivoted~aboùt~a member which~ pivoted ~about,the gene-30:~rally :ho~izontal pivotal axis for~:retra~tion of theass:ociated hydrofoil such that~8aid~'member is locked in posi~ion~for normal operation and i~ released: ~or re-traction~such that said hydrofoil~retracts pivotally ; with~its associated surface~sensing means.

~, ~
:~ ~: SUBSTI~UTE SHEET

W092J22396 PCT/EP92/013~;

. . .

A wind powered or assisted hydrofoil craft with the herein above described attributes will require a system to control the various hydrofoils and wing ~ Larger craft will most probably require a ~-~lly ~utomatic con-trol system similar in functionality to that of a large : civil airliner.
~ ~ Thus a control system for such a craft shall preferably : :i provide continuous control of the craft~ both prior to lift-off and in the foil-borne mode, b~ sensing mo-: 10 tions~: combining the motion signals with the manual pilot commands,: and conYerting these into appropriate control: surface::deflections such that the craft travels smoothly in the desired direction and at the desired speed and the~craft is not at any t-me in danger of 15; pitch-poling:~or~ rolling over or of being over-stressed due to::exGessive forces being generated by the wing or wi~gs.::In:~the~ foil-borne mode the control system shall also prev~t ~the :generally hori~ontal fully submerged foi~ls~Prom~emerging ~rom the water surface or th hull 20:~being impaated~by waves.
A~ simpler~ control system for :small leisure craft or other~ less~ demànding~ applica~tions may be split such t~h~at~,ra ~ ~sur~ace ~ sing~m ans~me ~ anically li ~ ed to ¢"' ~the~ generally-. ~ zironta~ p~iv e ~ hydrofoil sections 25~ such~as to~control~their anqlè:: of: attack are provided as heretofore described~to~control~ craft ride heigh~, pitch,; and:~roll, whilst an electronic system may pro-vide foil ~immersion protection direction of motion, tack se1ection,~ speed control , and stress~control. The , wing fl:ap:and wing tip rotation functions may be combi-ned to minimise control forces~and to enable a single actuator~to~be used for th~is~purpose, and a secondary : actuator:may:be provided:to contr~1 the ratio between flap deflection and wing tip rotation.

~: , :
::: : :
:
~UBSTITUTE SHEET

~92/22396 PCT/EP92/01~2 21112~

According tQ a seventh independent aspect of the pre-sent invent.~n any wind pow~red or assisted craft or vehicle comprising at least ohe upwards extending wing pivoted about a generally vertical ~axis and means to control the angle of attack of said wing or wings and further comprising:steering means in which the angle of ~ ~ attack of the wing or wings is controlled by a pedal ; : ~ similar to an accelerator pedal of a motor vehicle and where the steering means includes a steering wheel si-: lO~ milar to that of a motor vehicle and which may further comprise;a~c~ntrol similar to a ~gear lever of a motor vehicle to select the direction of motion in the fore and aft sense or may comprise a switch to select port of starboard tack and may comprise an electronic wing 15~-~ontroller~which~processes any input signals from said accelerator~:pe~al~ or from~said direction control lever or~ from said~ tack controI switch and which converts :said:signals`into:~suitable outputs for any wing actua-tors~ and~which~ may-comprise additional control ~eans 2~0~:wh~ich in-~`the case;:of a hydrofoil~water craft senses potential~:lift-out of:the windward lift producing hy-drofoil~and~in~the~-case of~water~ craft not being~hydro-foil~J~craft o ~ in~ ~ e~ case of~land or~ craft ox vehi-: cles:~sences~possibleccapsize;~-and w~ich `a~pplies a signal 25~ :to the~electr~nic wing-~controller~such that the lift generated~ ;any controlled vertically~extending wing is reduced:~and which may comprise:stress control means such that if; any transducer:positioned at:any part of , ~ ~
the craft`~indicates that that~part of the craft or ve-30~ hicle~has~reached or is about:~to reach~ a pre-determined level of~ stress or strain or deflection a signal is applied to the~electronic wing controller such that the , .-~:: : lift of ~:any ~controlled vertically extending wing is reduced.

SUBSTITUTE SHE~T

W092/22396 PCT/EP92/01~

~ J ~,~

The objects, attributes and features of all aspects of the invention will be more readily apparent from evaluation of the following detail discussion of an embodiment taken in conjunction with~~the accompanying drawing which illustrate by way of example t~e princi-ples of the invention, in which :
- ~igure 1 is an:isometric view of the craft with its : hydrofoils lowered in the normal operational positi~n ;
- figure 2~ is: a~front view of the craft with its hydro-: ~ 10 foils lowered in the normal operational position ;
- figure 3 is an isometric view of the craft with its :hydrofoils lowered for normal operation ;
- figure 4 is a side view of the craft with its hydro-:f~ils Iow red: ;
15 :- figure::5 is a:front view of the craft with its hydro-foils raised~;for docking ;~
figure 6 i6;~an~isometric view of the craft with its laterall hull ;extensions and:their attached hydrofoils fclded inwards~and :the wings stowed in the hull for 2~0 `transport ; :~
figure 7 is :a side view of the front hydrofoil and its attached~urface~sensor ; ~
-Ix~ f~igure~-8~ is~a~ view of~ the-front hydrofoil retracted ,,f~or~docking~or~transport~
25; -~figure~9 is ~a ~side view of:an alternative layou~ of the front hydrofoil ; :~
figure IO~:is a side view of the alternative front hydrofoil layou~ with the hydrofoil retracted for doc-king or transport. ; : :
30~ - figure ll;is a side-view of a rear hydrofoil and its : associated surface sensor ;
- - figure 12:is a partial view of a rear hydrofoil and its associated surface sensor. ;
~- :
figure 13 is a block diagram of the wing control sys-tem ; and : - .

SUBSTITUTE SHEET

~2/22396 PCT/EP92/01~2 ..

- figure 14 is a diagram of the wing flap and wing tip actuator mechanism.
A craft K comprises a body L on top of which i mounted wind p~wered aerofoil propulsion meà~s M and on the S bot~om of which is mounted hydrofoil means H. The craft K haæ a transverse (pitch) axis ZZ, a longi~udinal ~roll) axis XX, and a vertical (yaw) axis YY.
The body L~ compris~s a hull 1 and a cockpit 2. The~hull ~ ; is in the form of a slender d~lta lateral which has :: : 10 extensions 101, 102 at its aft end to support the rear : hydrofoil means~8 and to provide bu~yancy to stabilise : ~ -`: : ~ the craft X at low speeds.:The lower surface 104 of the lateral extensions 101, 102 form slender hydrodynamic : lifting:~surfaces~ The forward end of the hull 1 is 5::~broa~ened~to~provide protection for~the forward hydro-foil~means H:~and also to provid@~a suitable hydrodyna-mi~ surfaoe~lo3~ when the craft is hull-borne and pit-ched forward and a tunnel 105. The under~ide of the rear:~of the~hull 1 has a hing~d panel 106 arranged 20~above,the~static water ~ine ~WL. The lateral extension 101, 102~are~mounted on hingea 107 and are retained in th~ o ~ ating ~position.by a~clamp~ 108.~The coc~ it is env~elop,e~, ~ a~jwindscreenc.201 æteeriny~whee?~:202, ~an accelerato~pedal 203, and a 25~ direction~:controller 204a~ taak selector ~04b and wing variator:20~4c:which are combined~i~nto a sin~le control - 204.
The aerofoil~ means M comprises two upwards extending wings 3~mounted to a domed disk 3~.~Each of the wings has an~upper and a lower trailing edge flap 4a, 4b, and a detachable tip 5 rotatable about :an axis GG. The aerofoil means is freely pivoted about the vertically ~: inclined axis Y'Y'. The wings 3 are detachable from the : : domed disk 31 at 301.

C I IRc:TlTl IT~ ~T

W092/22396 PCT/EP92/01~.
211123g '`

The hydrofoil means H comprises a starboard hydrofoil 19 projecting down from beneath he starboard blank of the hull 1, a port hydrofoil 20 projecting down from beneath the port flank of the hull 1 and a forward hy-drofoil 2I projecting down from the front of the hull 1 .
Each of the port and starboard hydrofoils 19, 20 com-pr~ses a: horizontally extending section 193, 203 p~vo-~ ted to the lateral hull extensions 101, 102 to which a :: 10 vertically extending, water-piercing section 131, 201 is connected and a submerged horizontally inclined sec-: tion 192, 202 connected to the bo~tom of the vertical section.~The hydrofoils 19, 20 are pivotally mounted on the body::~L: ab~ut: collinear pitch axes E,E. The rear lS~ hydrofoils~;19, 20:may be rotated~ through approximately one ~hundred~and eighty degrees~ rearwards about the :pitah :axis~:~E:~uch` that` the normally horizontal sec-tions;192, 292 are lifted clear of the water f~r opera-tion in~shallow~water.::
2:0~ The forward~:~hydrofoil 21: comprises~ a vertical water-piercing~sect~ion~211~and a submerged horizontal section 2~12.~-The top~of~the: water-pièrcing:~section 211~is pivo-t~ .tal~ly~oùnted~in ?a~ trùnnion 22~ab ~ :p ah a tr ion 22 is pivotally `mou téd to~:thé o ~ ard: end of 25:~ the ~hu~ such:~as~to permit rotation about a vertical-ly~inclined~axis~CC. The forward hydrofoil~may be rota-ted through~ apprsximately ninety degrees rearwards ~f ~ about pitch~axis DD for operation in shallow water, hereby the lteadi~g edge of the ~normally vertical se~-30~:~tion:~emains partially submerged to retain steerage.
` : Figure 7 shows a layout of the:front hydrofoil 21 with its associa:ted surface sensor:40. A downwards extending : fin 213 is~attached tQ the lift hydrofoil 212 which is pivoted at ~ to the vertical surface-piercing hydrofoil :; : 3~5 211 which is pivotally attached at D to a yoke 22 which :
~: : . , C' l I D C~TITI IT~ ~ L~ ~

~ 92/22396 PCT/EP92/01342 2111239 ~ -is pivoted to the hull 1 about axis CC. The hydrofoil 211 is maintained in its lcwered position by tension in cable 215 which is attached to the vertical hydrofoil 211 in front of its pivot D such tXat a ~orwards and upwards extensîon of foil 211 abuts the front face of the yok~ 22 at H. The other end of the tension cable 215 is operated ~by a leYpr (not shown) via a compres-sion spring ~(not shown). A small surface-piercing~ hy-drofoil 401 is pi~otally attached to the lower end of a :.:
railing arm 402, the upper end of whi~h is pivotally :; attached to: a~ leading arm 404 the after end of which is also pivoted at D. A link 216 is articulated at P and is pivotally :attached to a rearward and upward exten-: sion of lead~ing arm 404 at its uppar ~nd -and is pivo-5 :tally attached ~to the lift hydrofoil 212 at its lower end. The~upper~portion 216a of link 216 runs in a guide 2:17~fixed to~he~verti~aI foil 211~ Link 216 is free to move~ in ~a passage 211' within the:vertical foil 211~ A
'T9~ member ~4QS~is attached to a slot in an upwards 4X-20 ~tension 402a of~trailing arm 402 and is pivotally atta-ched to:the fron~ end of a second leading arm 406. The rear;:end~ of~ the` leading arm 406 is pivotalIy attache~
to~the~yoks~`:22-~ab ve~the piv ~D A se~on trail-n a 03~is pi~o~ally~` ed 25~ di~g arm 404~ and at its lower :end to~the surfac~-pi~r-cing~hydrofoil:~401.
The above described mechanism is arranged such that :: generally upward: motion of the surface-piercing hydro : : foil 401:causes a downwards thrust in the link 2~6 such that the angle :of attack of the lift hydrofoil 212:is : increa~ed:such as to ~end to lift the front of the craft, The relation between the movement of the sur-: ~ face-piercing foil 401 and the rotation of hydrofoil : 212 can be adjusted by movement vf the T member 405 in ~: 35 the slot in the extension 402a of the trailing arm 402.
:

~ CTSTII~F ~-~ FFT

W092/2X396 PCT/EP92/01~

- 21112~9 . . .

A landing wheel 218 is pivotally attached to the verti-cal hyd~ofoil 211 such that it is maintained above ~he upper extent DWL' of the dynamic water line DWL.
Figure 8 shows the hydrofoil 21 in t~e raised position . 5 wherein cable 215 has been slackened and cable 214 ~ which i8 attached:to hydrofoil 211 ~ehind the pivot at : ~ D has been~tensioned by meanS of a lever (not shown) :, :
~ : such that the sloping rear upper face of the hydrofoil :: ` : 1 ~: 211 abuts the rearward face of the yoke 22 at H'. The 10 ~vertical hydrofoil 211 is maintained generally below : the static water line SWL and may be rotated about axis ~ CC~for steering. The hydrofoil 21 is:arranged such that :~ : -it lifts into the tunnel 105 of the hull 1.
In~:an alternative~ versi~n shown :in;figure 9 the lowe-15~ ring~cable~:~2~15 has an outer sheath~ lSa which abuts the leading ~arm~:404 ~locking it to the ~ertical` hydrofoil 2~ in~the ~lowered position and~the~lift hydrofoil 212 is ~pivoted~to ~the;lower end of the vertical hydrofoil 211 at P~.~The cable 215 is extended downwards and fixed 20;~to~:the lift hydrofoil 212 such~:~tha:t~:it abuts the lower face ~of~ the; vertical~ hydrofoil:~211. The~ leading arm :40~4,~ the~ vertical~:hydrofoil 211 :and~thejlift hydrofoil 2-12 thus"pivot about D as ~a unîty in this:case. As pre-viously~the~c~ble 215~is 61ackened~and~the ca~le 214 is 25~:`tensioned~:for :retraction. To provide: the necessary :reaction~ to~ prevent reversal~;of~the control moment a downwards~ extension 406a of ~the ~leading ~arm 406 has a cam follower~ 407 at its lower end which locates in a track 219~in;~the vertical hydrofoil 211 above pivot D.
The included;angle betwee~ the leading~arm 406 and the : upward extencion 402a of the trailing arm 402 is arran-, ; ged~ such~that a dswnward thrust is maintained on the : - surface-piercing hydro~oil-~401 whether the angle of : attack of hydrofoil 212 is positive or negative.
, ,, :: :
SUBSTITUTE SHEET
,. . . . .

W092/22396 PCT/EP92/01~2 Figure 11 et 12 show a layout of one of the rear hy-drofoils ~0 with its associated surface sensor 50. The hydrofoil 20 is pivoted about 'axis EE and h~s bearing~
: El, E2 located in the hull extension ~'02. The bearin~
El adjacent to the hydrofoil is located fore and aft but is unrestrained ~ertically. E2 is a spherical bea-~:~ ring. When the~hydrofoil 20 is in its lowered position a tension cable 225 maintains a pivoted member ~50~
: which is :separately pivoted about :axis EE against a stop S2 *ixed to the lateral hull extension 102. The other end of~the tension cable 225 ~is operated by a lever: (not shownj ;via~a compression spring (not shown).
A~ small surface-piercing hydrofoil 501 is pivotally attached to the lower:~snd of a trailing arm 502, th~
,:15~ upper ~end~o~ which:is pivotally attached to the inboard section:of~the laterally extending upper hydrofoil 203a of~hydrofoil~ZO~at ~ome distance in front of the axis EE.~ A:~'T'~,me~ber:~505:is~ adjustably :att~ched to a ~lot in~an upwards extension 502a of trai~ing arm 502 and is '2~0~p~ivota~1~1y~attached;to the front~end of a second leading arm~:506.-~The~rear end~of the~leading arm~:506 is pivo-`,t d ly ~ttachèd~ to~the~pivoted ~ember 508 above ths pi-r4,~ ~ot,'~a~ EE~Torpro~ide~`thè' nece e t~ion to pre-~
,7~ ,c~ ~ent-1rève' '1~ e ~co~tr ~m~ ènt à~'d rds:e ~ en-25 'sion:~506a~of:~th~'leadingiarm:~50~6~hâs a cam follower 507 at~its~ ower~ end~which locates::in~a~tra~k Z~29~ in the hydrofoil 20:above the pivot: axis EE. The included an-gle between the leading arm 506 and the, upward exten-sion 502a~:of ~the~trailing:arm~502 is arranged such that 30~ a downward ~thrust is maintained on the surface-piercing hydrofoil~501 whether the: angle of -attack of hydrofoil : 202 is positive or negative.: A landing wheel 238 is : pivotally: attached to the hydrofoil 20 and this toge-: ther with~the pivoted member -~08 acts as a keel when : .,:
~ : : 35 the hydrofoil 20 is retracted. A tension cable 224 : ~ ~

SUB~;TITUTEi~SHEET

W092t22396 PCT/EP92/01~

2~
which is attached to the pivoted member 508 is provided for retrsction and is operated by a lever (not shown).
The hydrofoil 20 is retracted by ~laakening the te~sion cable 225 and tensioning the cable -224. The pivoted member acts against the limit stop S3 fixed to the hy-drofoil 20 such that the hydrofoil 20 and the pivoted member 508 are rotated rearwards ~ogether. TQ lower the hydrQfoil cable 224 is slackened and cable 225 is,ten-sioned such that it abuts the limit stop S4 fixed to the hydrofoil 20 such that both rotate forwards toge-ther. ~
Figure 14 ~shows the mechanisms for actuating the wing flaps and tips.~ An actuator 14 is pivotally attached at one end~to~the~disk 31 which is pivotally attached to 15 ~the hull~ l~at~Y'~ and to which~the wings 3 ar~ attached and is pi~otally attached at its ~ther end to a lever 60~fixed~to th~ lower end of one of~the flaps 4b. Ano-ther lever~61 i8 ~ fixed to the -lower end o~ the other flap 4b~and~the two levers 60,~61~are pivotally connec-20~ ted~ ~ a rod~62~and are angled relative to flap~ 4b towhich they~àre;respectively attached ~uch that rotation of~-either~.flap~about its pivot~FP results in a desired differenitlal~otation~of the~other~flap.;Both flaps 4a, 4b~are~arranged~to-be deflected~y~ the~same amount and 25~ a ~torque~trànsmitting coupling is arranged betw~en them and~both~ f:laps ~a~e torsionally ~stiff~such that any ro-;~ ~ation of the bottom of one~of the lower flaps 4b re-~,sults in a similar rotation at the top of the upper flap 4b~fitted to the same wing.~Forwar~ pro~ecting slotted levers ~3a, 63~ are connected to the top of the upper flaps 4a and are aligned with their chordwise axes.
:
Further slotted levers 64a, ~4b are fixed to the pivot axes GG of the~two wing tips and are directed rearwards along the chordise axes of the wing tips 5. Actuators SUBSTI~UTE SHEET

W092,'22396 PCT/E~92/01~2 ._~
2 ~ 9 ; ' 7 ~ ~ ~

15a, 15b are pivotally attached to the forward facing levers 63a, 63b at the flap pivot axis FP and pins 65a, 65b fixed to the other end of these actuators engage in the slots in the levers 63a, 63b and 6~-a, 64b such that by extending and retracting the actuators 15a and 15b :: the ratic between the flap deflection of a wing 3 and the rotation of the tip 5 of the same wing is varied.
The basic aontrol system ~or the craft K is show~ in the form of~ a::simplified schematic circuit diagram in 10~ figure 13 in which signals from the direction control : 204a situated~in~the:cockpit 2 are applied to the wing incidence~and~:flap controller 39, to control the direc-tion~and amount of deflection of the flaps 4, ~a and :the:rotation for:~the wing tips 5. The direction control 15~ 204a has forward,~neutral and reverse po~itions.
An~accelerator~:203 situated in the;cockpit 2 allows the pi:lot ;to: control: the s~eed of the:::craft K by altering the:angle~;of atta~k of:the wings 3:and consequently the ;dr~iving~force~ generated. :Signals from ~he accelerator 20,~20;3~ and::~the~ combined c~ntrol 204 :are applied ~o the wing~:incidence~and flap~ controller:~39 which processes :the' ~inPut- si,gnals~'including ~feed-~ack signals from: the actuato~s~:14 and~wing tip ratio actuators 15a, 15b such at:thè~ t~ po 6~ in~t e~r uired m n e .
::,:25~' The,~:force~ tr~nSdUCer~45;measUres~ the~bending~:strain at the~ root of one~:;of the wings 3 and applies a signal to the~wing ~lap~and incidence controller~39: such: that if the gauged wing ~reaches its maximum level of dr:ive the angle~;~f~attack~of the- winqs~3~ is lim~ited b~ changing '3,0:~ the~angle:~of attaCk of the wing tips 5 and, if necessary, the~deflection of fl~ps 4a, 4b.
Signals from position transducers 43, 44 connected to the starboard and port surface-piercing foil means 50 ;":~ , enable the wing incidence and flap controller 39 to ~ 35 determine :whether the horizontal sections 192, 202 of SUBSTITUTE SHEEr W092~22396 PCT/EP92/01~

2 1 1 1 '~

the rea~ hydrofoils 19, 20 are about to lift ou~ of the water and in which case to limit the angle of attack of the wing 3 as above.
Whilst a particular ~orm of the inYentien has been 5 illustrate~ and describe~, it will be clear to those skilled in the art that ~odifications can be made wio thout departing ~rom the generality of ~he invention and it i5 acccrdingly not intended that the scope of the invention be limlted except as by the following : 10 claims.

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SUBSTITUTE ;:,HEET

Claims (62)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A wind powered or assisted hydrofoil craft comprising aerofoil means, hydrofoil means, hull means and control means in which :
- the aerofoil means provides a driving force to propel the craft, - the hydrofoil means provides vertical lifting forces both to support the weight of the craft and any verti-cal component of lift created by the aerofoil means and the hull means and to provide stabilizing moments to balance the craft about its roll and pitch axes and to provide horizontal forces both to balance components of the lift and drag forces in a direction parallel to the transverse axis of the craft created by the aerofoil means and the hull means and to provide a stabilizing moment to balance the craft about its yaw axis and steering means, - the hull means provides the balancing vertical lif-ting forces and moments abut the craft's pitch and roll axes which the hydrofoil means is unable to pro-vide due to an insufficiency of speed of the craft through the water and provides a cockpit for the crew, and - the control means provides means for steering the craft, means for controlling the motion of the craft about its roll and pitch axes, and for controlling the height of the craft above the water surface and means for controlling the aerofoil means, and in which :
- the aerofoil means comprises at least one upwards extending wing of rigid or flexible construction -the hydrofoil means comprises at least three hydro-foils arranged to provide both horizontal and vertical lift forces of which at least two are spaced about the longitudinal axis of the craft and of which at least one is spaced along the longitudinal axis of the craft relative to at least one other hydrofoil and which has means of adjusting its horizontal lift, and in which :
- the hull means comprises one or more hulls or floats arranged along and bout the pitch and roll axes of the craft such as to provide the necessary lift forces and righting moments about these axes and which further comprises means for connecting the hulls and floats, if more than one is provided, the hydrofoil means and the aerofoil means and for absorbing the forces generated by these means and controlling their deflections.

2. A craft as in claim 1 in which the hydrofoils disposed either side of the craft's longitudinal axis form a smooth downward-projecting extension to the hull means such as to form an end-plate thereby reducing aerodynamic drag.

3. A craft as in claims 1 and 2 in which the hydrofoil means remain sufficiently immersed when re-tracted to provide steering means and stabilisation about the craft's yaw axis.

4. A craft as in claims 1 and 2 which is equip-ped with wheels which lower when the hydrofoil means are retracted such as to facilitate launching.

5. A craft as in claim 1 in which the hull pre-sents three slender hydrodynamic lifting surfaces of moderate aspect ratio the centres of lift of which cor-respond approximately to the centres of lift of the three generally horizontal hydrofoils and which are presented at an angle to the water surface such as to create a minimum of drag at all attitudes of the craft prior to it becoming fully foil-borne.

6. A craft as in any claims 1 to 5 in which the hull means is extended in its width such that the late-really spaced hydrofoils are directly attached to it.

7. A craft as in any claims 1 to 6 in which in plan view the hull means forms a slender delta in which the apex of the delta being at the front of the craft is extended in its width.

8. Any wind powered or assisted craft or vehicle with aerofoil means in which the aerofoil means compri-ses at least one upwardly extending wing which is gene-rally tapered along its length such that the chord at its root is greater than the chord at its tip and in which any such wing is arranged with at least one trai-ling edge flap which is also tapered along its length having a fractional chord at its root greater than the fractional chord at its tip.

9. A craft as in claim 8 in which any upwardly extending wing is generally boomerang shaped.

10. A craft as in claims 8 or 9 in which any up-wardly extending wing has an additional pivoted tip section which can be rotated such as top operate at a generally different angle of incidence to the main wing section.

11. A craft as in claims 8 or 9 and claim 10 in which any wing can be twisted along its length such that its upper end is twisted relative to its lower end by the amount by which the tip section is rotated.

12. A craft as in any claims 1 to 11 in which the base of any upwards extending wing is positioned at a small distance from the water surface in relation to its length such that its effective ratio is substan-tially increased due to the mirror plane provided by the water surface.

13. A craft as in any claims 1 to 11 in which the surface of the hull means which abuts any upwards ex-tending wing is extended to act as an end plate for the wing in order to increase its effective aspect ratio.

14. A craft as in any claims 1 to 11 in which the surface of the hull means about which any upwards ex-tending wing sweeps as it rotates about its pivotal axis is a plane surface normal to said axis.

15. A craft as in any claims 1 to 12 in which the base of any wing is fixed to a planar or domed disk pivoted about a generally vertical axis.

16. A craft as in claims 10 or 11 in which the pivoted tip section of any wing is swept forwards or rearwards such that the angle of attack of the wing is controlled by rotation of the tip section by altering the balance about the pivotal axis of the wing.

17. A craft as in claim 16 in which the angle of attack of any group of pivoted wings is controlled by the angle of attack of at least one rotatable wing tip by altering the balance about the pivotal axis of the group of wings which is arranged to rotate freely as an entity.

18. A craft according to any one of the preceding claims 16 or 17 in which the angular position of any wing or group of wings is set by an actuator, the ba-lancing moment created by actuation of any wing tip or control aerofoil effectively reducing the control mo-ment supplied by the said actuator.

19. A craft as in claims 8 or 9 having two or more upwardly extending wings wherein the trailing edge flaps of any one wing are actuated differentially with respect to the trailing edge flaps of any other wing.

20. A craft as in claims 10 or 11 having two or more upwardly extending wings wherein the pivoted tip section of any wing is rotated differentially with res-pect to the tip section of any other wing.

21. A craft as in claims 1 to 20 in which any wing is buoyant and in which the centres of buoyancy of the wing means and any other immersed part of the craft in the capsized state are such as to provide sufficient righting moment to right the craft automatically.

22. A craft as in claims 1 to 20 in which any wing is buoyant and in which means is provided to ro-tate any wing or group of wings such that a capsized craft may be easily righted.

23. A craft as in claims 1 to 20 having at least two wings in which any pair of wings are arranged such that they splay outwards one to another being pitched more closely together at their lower than at their up-per ends.

24. A craft as in claims 1 to 7 or in claims 10 or 11 having at least two wings in which the tips of any pair of wings are arranged such that they splay inwards one to another being pitched more closely toge-ther at their upper than their lower ends.

25. Any wind powered or assisted hydrofoil craft with at least one hydrofoil in which any hydrofoil com-prising a vertical or vertically inclined water-pier-cing section and a horizontal or horizontally inclined normally submerged section has a horizontal or horizon-tally inclined pivotal axis substantially parallel to the transverse axis of the craft arranged such that the angle of attack of the horizontal or horizontally in-clined section and consequently its lift may be adjus-ted by rotating the hydrofoil about its pivotal axis in a manner which enables the hydrofoil to develop similar values of lift in the upwards and the downwards sense.

26. A craft as in claim 25 in which the horizon-tal or horizontally inclined section of any hydrofoil having a vertical or vertically inclined section and a horizontal or horizontally inclined section is pivotal-ly attached to the lower end of the vertical or verti-cally inclined section.

27. A craft as in claim 25 in which the horizon-tal or horizontally inclined pivotal axis is arranged such that it is above the water surface for normal foil-borne operation such that both the horizontal or horizontally inclined section and the vertical or ver-tically inclined section rotate about the pivot axis as a unity.

28. Any hydrofoil supported craft which comprises a hydrofoil pivoted about a horizontal or horizontally inclined axis close to the static water line of the craft and in which the hydrofoil comprises a horizontal or horizontally inclined section arranged such that it provides additional lift during hull-borne operation and such that it is above the water surface for normal foil-borne operation and a downwards extending vertical or vertically inclined section and a further horizontal or horizontally inclined section which is fully submer-ged for normal operation.

29. A craft as in claim 28 in which the two hori-zontal or horizontally inclined sections and the verti-cal or vertically inclined section form a generally 'C' shaped entity.

30. Any hydrofoil supported craft in which any hydrofoil includes a horizontal or horizontally incli-ned hydrofoil section pivotally attached to the lower end of any vertical or vertically inclined hydrofoil section in which its pivotal axis is arranged slightly behind its centre of lift and to which is attached a downward projecting fin and is arranged such that for forward motion the sum of the moment created by the vertical lift component generated by said hydrofoil section together with the moment created by the drag generated by said fin about the pivot axis of said hy-drofoil section always acts in the same sense whether the said vertical lift component be in an upward or downward sense.

31. Any hydrofoil supported craft in which - any hydrofoil comprising a vertical or vertically inclined water-piercing section and a normally submer-ged horizontal or horizontally inclined section can be rotated about a horizontal or horizontally inclined pivotal axis situated above the normal water level for foil-borne operation such as to vary the vertical lift component it generates and - in which such pivotal axis is largely unconstrained for translational movement in a generally vertical sense and - in which the vertical lift component generated by said hydrofoil is largely resisted by part of the craft which is translational mobile in a generally horizon-tal sense relative to said pivotal axis such that the moment required by any actuator or control mechanism to rotate said hydrofoil about said pivot axis or to main-tain it in position is substantially reduced.

32. A craft as in claims 25, 27, 28, 29 or 31 in which any hydrofoil having a horizontal or horizontally inclined pivotal axis may be pivotally retracted for-wards or rearwards about its axis such that the draft is substantially reduced for: docking or operation in shallow water.

33. A craft as in claim 25, 26 or 27 which is arranged with an additional pivot axis close to or above static water-line and which is locked during normal foil-borne operation such that the hydrofoil may be pivoted forwards or rearwards about this additional pivot axis enabling a substantial reduction in draft for docking or operation in shallow water.

34. A craft as in claims 28, 29, 30 or 31 which is arranged with an additional pivot axis close to the intersection of the horizontal or horizontally inclined and the vertical or vertically inclined foil sections and which is locked during normal foil-borne operation such that the hydrofoil may be pivoted forwards or rearwards about its horizontal or a horizontally inclined pivot axis enabling a substantial reduction in draft for docking or operation in shallow water whilst the horizontal or horizontally inclined foil section section is pivoted about the herein above described additional pivot axis such that its angle of incidence remains largely unchanged.

35. A craft as in claim 33 in which the angle of attack of the horizontal or horizontally inclined sec-tion is largely unchanged during rotational retraction of the hydrofoil about its additional pivotal axis.

36. A craft as in claims 25 to 35 in which cable means are provided to lower any hydrofoil about its pivotal or its additional pivotal axis and to lock said hydrofoil about such additional pivotal axis if saidhy-drofoil is so equipped.

37. A craft as in any of the claims 25, 27, 28, 29, 31, 32 and 34 in which any hydrofoil with a verti-cal or vertically inclined section and a horizontal or horizontally inclined section and which is pivoted about a horizontal or horizontally inclined axis has an actuator for adjusting the angle of attack and uses the same actuator to retract said hydrofoil.

38. A craft as in claims 32, 33, 34 and 35 in which any hydraulic or pneumatic actuator used to re-tract any hydrofoil has at least one pressure relief valve or accumulator in its control circuit for the purpose of providing compliance such that any such hy-drofoil when impacted by a body may rotate rearwards against the compliant force provided by the control circuit to relieve the impact.

39. A craft as in claims 25 to 37 in which any hydrofoil additionally comprises spring means such that if impacted by a body it may rotate rearwards about its axis for retraction in a compliant manner.

40. Any hydrofoil supported craft which comprises at least one hydrofoil which comprises a horizontal or horizontally inclined section on and further comprises a horizontal or horizontally inclined pivot axis and which is connected to surface sensing means comprising a mechanism which determines the height of some point of the craft relative to the water surface and provides a controlling force to adjust the upward or downward lift component generated by said hydrofoil such as to tend to maintain any part of the craft at a controlled height relative to the water surf ace and in which :
- said surface sensing means includes two leading arms each of which is pivotally attached towards its rear end to some fixed or mobile part of the craft and is further pivotally attached to a joining link towards its forward end so at to form a parallelogram and in which :
- a downwards extension to said joining link forms a trailing arm.

41. A craft as in claims 1 to 40 in which any hy-drofoil together with the surface sensing means to which it is connected is arranged such that it can pro-vide similar amount of lift in both an upwards and a downwards sense.

42. A craft as in claim. 1 to 41 in which any surface sensing means is a compact arrangement and in plan projection is contained within the contours of the craft such that it is thereby afforded protection.

43. A craft as in claims 1 to 41 which incorpora-tes means in which the gain of any system comprising a hydrofoil and its associated surface sensor means can be readily adjusted such as to adapt the dynamic beha-viour of the craft to local wind and sea-state condi-tions.

44. A craft as in claim 25, 26 or 27 and claim 40 comprising at least one hydrofoil linked to surface sensor means which includes a pair of leading arms and in which one of the leading arms is linked to said ho-rizontal or horizontally inclined hydrofoil section such that upwards rotational movement of the forward ends of said leading arm causes an increase in the an-gle of attack (which may be a decrease in the negative angle of attack) of said hydrofoil section, and such that upwards rotation of said leading arm has the re-verse effect.

45. A craft as in claim 44 in which the rear pi-votal axis of the trailing arm to which said horizontal or horizontally inclined hydrofoil section is linked is substantially collinear with the pivotal axis for re-traction of the hydrofoil such that if said hydrofoil is retracted the angle of attack of said horizontal or horizontally inclined hydrofoil section is not substan-tially altered.

46. A craft as in claims 28, 29, 30 or 31 and claim 40 comprising at least one hydrofoil linked to surface sensor means which includes a pair of leading arms such that the lower leading arm is formed by a forward extension of a vertical or vertically inclined hydrofoil section.

47. A craft as in claim 40 and claims 44 or 46 in which said trailing arm comprises a small surface pier-cing hydrofoil at its lower end such that a movement of said trailing arm caused by a change in the lift gene-rated by said surface piercing hydrofoil as it rides along the surface of the water as a result of some change in the craft's attitude of wave motion, causes rotational motion of the lower leading arm thereby al-tering the angle of attack of the horizontal or hori-zontally inclined foil section to which it is connec-ted.

48. A craft as in claim 47 in which said trailing arm is shaped to provide limited hydrodynamic and buoyant lift and to generate low drag when immersed.

49. A craft generally as in claim 47 in which said trailing arm is pivotally attached to a small sur-face piercing hydrofoil at its lower end and in which a second trailing arm is pivotally attached to the lower leading arm at its upper end and to said surface-pier-cing hydrofoil at its lower end such that the two trai-ling arms generally form a parallelogram and such hat the angle of attack of said surface piercing hydrofoil remains sensibly constant or is controlled to vary in a desirable manner.

50. A craft as in claim 49 in which said trailing arms are shaped to provide limited buoyant lift and to generate low drag when immersed.

51. A craft as in claims 40 ad 43 in which the gain is altered by variation of the length of the joi-ning link connecting the forward ends of the leading arms.

52. A craft as in claim 31 and and of claims 47, 48, 49, 50 and 51 in which a generally vertical exten-sion of the upper leading arm locates in a track atta-ched to the hydrofoil generally above or below its ho-rizontal or horizontally pivotal axis such that said extension supports the generally vertical cal lift compo-nent generated by the hydrofoil in either an upwards or a downwards sense and is arranged such that the inclu-ded angle between the forward end of the upper leading arm and the link between the forward end of the two leading arms is such that the combined effect of the moment generated by the hydrofoil about its pivotal axis and the vertical component of lift it generates always produces a downward thrust on said surface-per-cing hydrofoil of said surface sensor means.

53. A craft as in claim 52 in which said upper leading arm is pivotally attached to a member which is pivoted about the horizontal or horizontally inclined pivotal axis of the associated hydrofoil such that for normal operation said member is locked in position and is released for retraction such that said hydrofoil retracts pivotally with its associated surface sensing means.

54. Any wind powered or assisted craft or vehicle comprising at least one upwards extending wing pivoted about a vertical or vertically inclined axis and means to control the angle of attack of said wing or wings and further comprising steering means in which the an-gle of attack of the wing or wings is controlled by a pedal similar to an accelerator pedal of a motor vehi-cle and the steering means includes a steering wheel similar to that of a motor wehicle.

55. A craft as in claim 54 in which the means for controlling the direction of motion of the craft in the fore and aft sense includes a control similar to the gear selector of a motor vehicle.

56. A craft as in claims 54 and 55 which compri-ses at least on hydrofoil which has means to control its lift and which has additional control means such that if the horizontal or horizontally inclined section of any hydrofoil approaches the surface of the water too closely such that it is in danger of emerging from the water the angle of attack of any upwards extending wing is adjusted such as to reduce the downwards lift component required to be produced by that hydrofoil section.

57. A craft as in claim 54 or 55 which has addi-tional control means such that when being used on land or ice and any wheel or skid is in danger of lifting more than a specified amount from the surface or alter-natively the craft is in danger of exceeding a pre-de-termined roll or pitch angle the angle of attack of any upwards extending wing is adjusted such as to reduce the lift produced by any upwards wing such as to stabi-lise the craft.

58. A craft as in any of the preceding claims 55 to 57 which has additional control means such that if any transducer positioned at any part of the craft pro-duces a signal which indicates that the level of stress or strain or the load being carried by that part of the craft is above a pre-determined value the angle of at-tack of any upwards extending wing is adjusted such as to restore the value of the stress, strain, or load in that part of the craft to the pre-determined level as a maximum.

59. A craft as in any of the preceding claims 1 to 58 which as at least one upwards extending wing any of which comprises at least one trailing edge flap and a pivoted tip section as a single actuator to control both the deflection of said trailing edge flap or flaps and the rotation of said tip or tips.

60. A craft as in claim 59 in which the ration between flap deflection and the rotation of the pivoted tip section of any wing is variable and is controlled by an actuator.

61. A craft as in claims 59 or 60 in which for any wing or group of wings, the control moments requi-red to control the deflection of at least one flap and the control moment required to control at least one pivoted wing tip are combined in a manner as to reduce the overall control moment required.

62. A craft as in any of the preceding claims 1 to 61 which has an electronic control system to control the sense and the amount of lift produced by any verti-cally inclined wing.