Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~ 23589-89
The invention relates to a rudder for ships travelling
in ocean areas where -there is an ice risk.
Ships travelling in areas where there is an ice risk,
often have difEiculties in keeping their course stable, particu-
larly when moving astern, due to drifting ice. The reason is
that the rudder action is impaired by the ice and in fact the
rudder can even be damaged, because an adequate ice repelling
action cannot be ensured and also the rudder is exposed to a
high pressure side action.
The problem of the present invention is to improve
the rudder action, whilst simultaneously improving the pres-
sure side action on the rudder, the course stability and the
propeller efficiency of ships travelling in ocean areas where
there is a risk of ice, even when moving astern.
The present invention provides a rudder for ships
travelling ocean areas where there is an ice risk, wherein the
rudder has a rudder blade, the rudder blade having a rear end
and being provided with a lift prestress profile, which is
constructed as a thickened portion that widens symmetrically
towards the rear end, said rear end of the rudder blade being
provided on each side with one sharp edge, said rear end of the
rudder blade having an ice cutter terminally tapering in blade--
like manner and having lateral outer side walls of the ice
cutter whlch pass into the lift prestress profile of the rudder
blade, accompanied by the formation of said sharp edges, via
wall sections extending perpendicularly to the longitudinal axis
of the rudder blade, the rudder including a guide head at the
forward end thereof.
Due to the lift prestress profi].e, the case of a zero
rudder angle amidships produces a lift on either side of the
rudder in opposite directions and therefore compensating one
another. There is a very marked increase in the l.ift, even in
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the case of the smallest rudder angles, because i-t is reduced
on one side and rises sharply on the other side, building up
on the prestress.
The provision on each side of a sharp edge, signifi-
cantly improves the pressure side action. Accompanied by the
formation of sharp edges, the outer wall faces of the ice
cutter can pass into the liEt prestress profile of the rudder
blade, so that an ice repelling action is possible, when the
ship is moving astern.
The rudder may be combined with a rotor rudder, where
there can be two different constructional embodiments:
a) the rotor is housed in a fixed rudder post or in
a guide head, or
b) the rotor is housed in the movable part, i.e. in
the rudder blade, the rotor being hydraulically, electrically
or mechanically drivable by a drive in the ship.
To prevent twist of the slipstream, the rudder post
may also be provided with a sweep back, which can once again be
combined with various possibilities for the rudder arrangement
and association.
To increase the course stability and improve the
propeller efficiency, the rudder blade may be provided with a
Costa member constructed in per se known manner, so that the
slightly increased resistance of the rudder with the lift pre-
stress proEile is compensated again by a simple measure, which
is advantageous in ice.
Further adv~ntageous developments of the
invention can be gathered from the subc]aims.
The invention is described in greater detail
hereinafter relative to em~odiments and the
attached drawings~ wherein show:
Fig. 1 the blade of a rudder with a lift
prestress profile, a shaped-on ice cutter
and sharp edges forrned on either side of
the rudder blade.0 Fig. 2 the rear end area of t~.e rudder blade
accorcling to Fig.1 cn a ]arger scale.
Figs. 3, the rudder blade provided wi-th a lift
4 and 5 prestress profile having a fixed guide
head in different constructions.
15 Fig. 6 a rudder blade according to Fig. 1
with a lift prestress profile and with
a rotor arranged on the leading edge
side.
Figs. 7, a rudder blade according to Fig. 1 with
2U 8 and 9 an upstream positioned guide heacl,
which is frontally provided with a rotor,
in different constructions.
Figs. 10, a rudder blac7e according to Fig. 1,
11 and 12 wi-th an upstream fixed`guide head with
a rotor arranged between the latter and
the rudder blade~ in different constructions.
Figs. 13 a rudder blade according to Fig. 1 with
and 14 an ups-tream fixed guicle head, a rotor
arranged betwcen the latter and the rudder
3;0 blade and a ~urther rotor arranged on the-
leading edge of the guide head, in
- different constructions.
.
Figs.~15l the rudder blade of Fig. 1 with a rotor
16 and 17 arranged on the leadlng edge side and an
.
upstream guide head, in di~ferent
constructions.
Figs. 18, the r~dcler blade of Fig. 1 with a ro-tor
19 and 20 arranged on its leading edge, and an
upstream fixed guide head, carrying on
its leading edge a further rotor, in
different constructions. '
F],g. 21 a rudder blade with a Costa me~lber
in a plan view.
,Fig. 22 a side view,of the rudder blade of Fig. 1.
F'igo 23 the rudder blade with a sweepback formed
on its end.
Fig. 24 the current path in the case of a rudder
profile with a lift prestress and the
rudder at a zero angle.
Fig. 25 the current path for a rudder profile
with a lif`t prestress with the rudder angle
differing from zero degrees.
Fig. 26 the current path in the case of a rudder
~ 20 profile with a lift prestress with a
- fixed guide head connected upstream of
the rudder bl~ad~eD
Fig. 27 the current.path in the case of a rudder
profile with a lift prestress and a rotor
connected upstream of the rudder blade.
Rudder 10 of Figs. 1 to 23 comprises rudder
blade 11, which is pivotable about the pivot axis
12 by means of drives, which are not shown in the
drawings. The rear end of rudder blade 11 is designa-
~ ted lla ~nd the leading edge thereo~ is designated
13.
The blade 11 of r~dder 10 is provided at its
end lla in the embodiment shown in Figs. l and 2
with a profiling or profiled member which, in the
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case o-f a zero rudder angle, produces on either
side of the rudder, oppositely directed and therefore
self-compensating lift effects. This lef-t prestress
profile is designated 20 and is constructed as a
symmetrical thickened or widened portion 21 of end
~la of the rudder blade.
Normal rudder profiles give rise a-t the
rudder head to a compression of the current path,
which leads to -an underpressure and in the case of
1-0 correct configuration in point ~ brings about a
forwardly directed buoyancy, so that the profile
resistance is raised (Fig. 24). As a result of
a symme'crical thickened portion 21 of the rudder
end, the current in contact with the profile
undergoes fur-ther acceleration at point B, which
gives rise to an additional buoyancy vector and
produces a lift prestress. At a rudder angle, the
transverse force on the back is considerably
increased, so that the current is deflected more.
Although the current deflection is less on the
- suction side, the profile shape with its lift
.
prestress produces an additional buoyancy, so that
the overall rudder trasverse force is improved
- (Fig. 25).
This lift prestress profile 20 is obtained
by the symmetrical thickened or widened por-tion 21
at end lla of blade 11 of rudder 10.
TQ prevent an uncontrolled separat1on of the
current, on either side of rudder blade 11, the
lift prestress profile ~0 passes into sh~rp edges
22 (Fig. 2). A corresponding dead water behind
the rudder blade acts in the same way as a profile
~ extension and, on adjust~ent, also increases the
- rudder action.
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According to another embodimen-t blade 11 of rudder 10
has in the vicinity of the liEt prestress profile 20 an ice
cutter 25, which terminally tapers in blade-like manner. When
the ship is moving astern in ice, this leads to the particular
advantage -that the ice is repelled by this cut-ter. The outer
wall surfaces 25a oE ice cutter 25 pass into the lift prestress
profile 20 of rudder blade 11, accompanied by the formation of
sharp edges 22 on ei-ther side, via wall sections 25b extending
perpendicularly to the longitudinal axis of the rudder blade.
However, it is possible to provide other profiles or
profiled members at the rudder end, but they must be such that
a lift prestress is obtained, i.e. the profile or profiled
member at the rudder end must be such that in the case of a
zero rudder angle amidships a lift is produced on either side
of the rudder, which is oppositely directed and therefore is
self-compensating. However, even in the case of the smallest
rudder angles, the lift rises very sharply, because it decreases
on one side, whilst on the other side, building up on the
pres-tress, it rises sharply. The possibility also exists of
providing the rudder post of rudder 10 with a sweepback 60
(Fig. 23), whose end areas are then interconnected or pass into
the ice cutter 25, so that the ice is repelled when the ship
is moving astern in ice.
By fitting an ice cutter 25 behind the lif-t prestress
profile 20, the rudder can also be used for the highest ice
class and the rudder blade and spindle are effectively protected
when moving astern. In the manner shown in Figure 2, apart
from being shaped like an ice cutter, it can be provided with
ice-repelling surfaces.
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The rudder lO sho~ in Figs. 3 to 20 and
provided with 1;he rudder b]ade ll having the lift
prestress profile 20 is combined wi-th a guide
head and/or rotors, in accordance with the
- 5 various embcdiments.
According to Figs. 3 to S, rudder blade ll
of rudder lO is provided with a fixed guide head
- 30, which is connected upstream of the pivotable
blade ll and can be shaped in many different
~o ways.
In the embodiment of Fig. 6, blade ll of
rudder 10 is provided with a rotor 40, which is
positioned on the leading edge 13 o~ blade ll.
Figs. 7 to 9 show various embodiments of a
rudder blade ll with an upstream fixed guide head
30, which carries on its leading edge side a rotor
140. Rotor 140 can have different diameters and
the fixed guide head 30 can have di~ferent shapesO
In the case of the embodiments shown in
~igs. lO to 12, between blade ll of rotor lO and
fixed guide head 30 is provided a rotor 24~. Once
again the guide head 30 can be shaped in different
; ways and the rotor can have different diameters.
- It is possible to arran~e rotor 240 between rudder
blade ll and guide head 30. Howevér, it is also
possible to positioned rotor 240 in the rear area
of guide head 30.
According to the embodiments of Figs. 13 and
14~ a rotor 240 can be arranged between blade ll
of rotor lO and the fixed guide head 30, whilst
on its leading edge side guide head 30 also carries
a rotor 140.
In the embodiment of Figs. 15 to 17 the rudder
blade ll carries on its leading edge side rotor 40.
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A fixed guide head 30 is positioned upstream
of the thus constructed rudder blade 11 with rotor
40.
Bo-th rudder blade 11 and the upstream guide
head 30 can be provided in each case with a rotor.
In accordance with Figs. 18 to 20, on the leading
edge side of rudder blade 11 carries a rotor 40
5uide head 30 is also provided on the leading
edge side with a rot~r 140. Once again guide head
1030 can have dif~erent shapes and rotor 40 or 140
can have different diameters.
Rotors 40, 140, 240 are driven hydraulically,
electrically or mechanically, preferably by a not
shown drive arranged in the ship.
15To improve the course ~tability ~nd improve
the propeller efficiency, according to the
embodiment of Figs, 21 and 22 blade 11 of rudder
10 is provided with a Costa member 50. This is
constituted by toroidally shaped portions on the
two rudder blade side walls.
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