Note: Descriptions are shown in the official language in which they were submitted.
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
W092/22396 PCT/EP92/0l~
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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W~Og2/22396 PCT/EP92/01~2
3 9 .- `
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
W092/22396 PCT/EP92/01~?~
.
2111239
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
2111239
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
,~
~ 1 IPs.~TlTI ITr C~Ll~T
W092/22396 PCT/EP92/01~
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
- 2111239 -
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~
W092/22396 PCT/EP92/01~
2111239
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
2111239
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
:
~ SUBSTITUTE SHEET
W092/22396 P~T/~P92/01 ~
. .
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
2111239
11
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.
:
~,
: ~ ': :
1 IR.C~TITI ITr ~T
W092~223~6 PCT/EP92~013~
2111239
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
,
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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 ` ~ .
W092/22396 PCTlEP92/01~
21112`39 ~
14
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
~, ~
: ~
~ :: SUBSTITUTE SHEET
,, _ , ~ wr:
W~Q g2,22396 PCT/EP92/01342
~` 211123~
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
~ : ~
~ SUBSTITUTE SHEET
., ., .. . .. .... , .. ....... .. , ~ .. , .. ... . ~, .. . .
W092/22396 PCT~EP92/013~
2111239
16
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
.. . . . .
17
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`
18
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
19
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~;
2111239
. . .
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~
21
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
2111239
W092/22396 PCT/EP92/01~
~ J ~,~
22
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
2111Z39
..
- 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 '`
24
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
. . .
26
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
2111239
27
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
: ~ ~
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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
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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
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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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