Ships – Steering mechanism – Rudders
Patent
1983-02-25
1985-05-07
Blix, Trygve M.
Ships
Steering mechanism
Rudders
114140, 244209, B63H 2538
Patent
active
045151016
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a rudder for boats and ships or, in other words, a rudder that can be used both for small vessels which are usually classed as "boats" and for larger vessels, and both for propeller-driven vessels and sailing vessels.
However, the rudder according to the invention also has other fields of application, for instance as a stabilizer, trim flap, keel and centerboard and, possibly, also fields of application outside the maritime sphere, for instance in aircraft, as a wind deflector, for example on large trucks, as well as other uses. Generally speaking, the invention thus is applicable to flow-modifying elements, but will be described in the following substantially with reference to ships' rudders.
It is an old-established notion to make a rudder hollow from its leading edge to its trailing edge, and this notion has been brought up again from time to time. U.S. Pat. No. 2,961,987 points out by way of introduction, and quite correctly, that the deflection of a rudder sets up hydrodynamic pressure on the pressure side of the rudder and a sub-normal pressure on the suction side of the rudder, whereby a strong eddy is produced in the vicinity of the rudder, producing a restraint on the ship's speed without having any useful effect on the desired rudder action. To reduce the flow resistance and to avoid eddies in order to reduce the propulsion resistance, this patent specification proposes a rudder having a series of flow passages which extend alternately from the opposite sides of the rudder from a vertical line near the leading edge of the rudder to the trailing edge thereof, the flow passages which extend at an angle relative to the rudder plane from one side of the rudder crossing the corresponding passages proceeding from the opposite side of the rudder without intersecting these passages because they lie in different vertical planes. The water is intended to flow into the passages proceeding from the pressure side of the rudder and to flow out on the suction side.
However, this prior art construction does not provide any favourable effect on drag and lift because the passages cross the rudder diagonally and, besides, set up a high flow resistance, for which reason they permit neither a sufficient throughflow quantity nor a sufficient flow velocity to achieve the objects stated in this patent specification.
A further disadvantage is that the known rudder upon zero rudder deflection contrary to a favourable effect causes considerable difficulties because the passage arrangement illustrated sets up a high water resistance and makes the rudder unstable.
Finally, it should be mentioned that the passages of the known rudder cause constructional differences increasing the costs.
The object of the present invention is to provide a rudder which has a favourable effect both on the pressure side and on the suction side and stabilizes the ship's way through the water from zero position of the rudder to maximum rudder deflections.
These objects have now been achieved in that the rudder according to the invention has been given the characteristic features stated in claim 1 and, for preferred embodiments, the characteristic features which are stated in claims 2-5.
The invention will be described in more detail below, reference being had to the embodiments illustrated in the accompanying drawings in which
FIG. 1 is a schematic view of a sailing-boat of the fin-keel type having a hollow rudder and a hollow fin-keel according to the invention,
FIG. 2 is perspective and more detailed view of a hollow rudder according to the invention,
FIG. 3 is a schematic section of a part of the rudder shown in FIG. 2,
FIG. 4 is a perspective view of the rudder shown in FIG. 1, mounted behind a tail piece,
FIG. 5 illustrates an alternative embodiment of a hollow rudder according to the invention,
FIG. 6 is a diagram illustrating the concepts "drag" and "lift" applicable to all rudders,
FIG. 7 illustrates, in the form of a diagram, the relations between drag and speed in a hollow rudder of the type which is show
REFERENCES:
patent: 2484359 (1949-10-01), Tipton
patent: 2873931 (1959-02-01), Fleischmann
patent: 2961987 (1960-11-01), Mello
patent: 3128063 (1964-04-01), Kaplan
patent: 3184185 (1965-05-01), Brocard
patent: 3604661 (1971-09-01), Mayer
patent: 3680511 (1972-08-01), English
Blix Trygve M.
Corl Rodney
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