US3230920A - Ship's steering rudder - Google Patents

Description

Jan. 25, 1966 J. w. PlSKORZ-NALECKI 3,230,920

SHIP'S STEERING RUDDER Filed May 28. 1964 NH ml ORNEYS United States Patent Ofiice 3,230,920 Patented Jan. 25, 1966 3,230,929 SHIPS STEERING RUDDER Jerzy W. Piskorz-Nalecki, Gdansk, Poland Filed May 28, 1964, Ser. No. 370,775 4 Claims. (Cl. 114-162) The present invention relates to a ships steering rudder and more particularly to such a rudder that increases the maneuverability and steering effectiveness of ships.

The present invention also provides a construction of a ships steering rudder which can be used on all types of oceangoing and river vessels, as well as on warships.

At the present time, rudders are used which are made from a fiat, generally rectangular plate, as well as the so-called displacement rudders which, in a cross-section parallel to the Waterline of the ship have the shape of a symmetrical drop profile. There are a large number of such profiles which have been tested by various institutions and serve as prototypes for the design of the rudders.

The lift which is produced on the surface of the rudder can be calculated by the following formula:

p is the density of Water kg./m. C is the lift coefficient As can be noted from the above formula, the value of the lift produced on the rudder blade is directly proportioned to the square of the velocity of the water V coming against the rudder area S, and to the lift coefficient C In planning-the rudder for a given ship, the value of the velocity V is normally given, while the value p is a constant for seawater or fresh Water, and therefore these values cannot be influenced. For the planning of the rudder, therefore, the rudder profile must be provided which gives the greatest effectiveness in steering, and therefore the largest possible lift coefficiency C as well as the rudder area S. It is well known that the value of the coefiicient C in the function of the rudder swing angle a depends in particular on the length A of the rudder and therefore on the ratio of its height h, to its width The physical importance of this feature is explained by the fact'that when placing the rudder at an angle to the oncoming stream of water, there is produced on one side of the rudder a high pressure zone designated and on the other side a low pressure zone designated as a result of which there is obtained around the upper and lower edge of the rudder a water fiow which seeks to equalize these pressures. The lift, however, is a function of the pressure differences on both sides of the rudder, and the greater the speed of the flow around its edges, the smaller the lift of the rudder. For a given profile, the maximum value of the lift coefficient is, aside from its length, the same, but the angle of impact a, i.e., the angle between the oncoming water stream and the axis of symmetry of the rudder profile at which this maximum occurs depends primarily on the length of the profile.

An increase of the length of the rudder causes the widening of the angle of inclination and therefore a faster rise of the curve of the lift coefiicient C as a function of the angle of impact. The greater, therefore, the length of the rudder, the more rapid the increase of the lift L in the swing of the rudder, the maximum lift being obtained with a smaller swing angle than in the case of a rudder of small length. However, it is known that a rudder has good maneuverability when its profile, for a given area, gives the largest possible rudder moment, and the largest relative moment with respect to the rudder swing. As a result of the increased lift which occurs with this swing angle of the rudder, its component perpendicular to the plane of symmetry of the ship is also increased, so that there is an increase in the ships moment of rotation, and thus the ship maneuvers better.

For instance, it may be mentioned that the lift coefficient C of the rudder having a so-called Gdttingen Profile 538, with a length A of 1.47 and swing angle o=l(l, is 0.45; in the case of a rudder having a length )\=4 with the same swing angle, the lift coefiicient C is 0.70. This means an increase in the lift coefficient of 55% for this swing angle of the rudder. The lift of the rudder and its component also increases in the same ratio, whereby the turning of the ship is caused, which favors the maneuvering properties of the ship.

The length of the rudder also permits the full utilization of the rudder area. This consists in the fact that in the case of small lengths as well as in the case of limited swing angles of the rudder, the maximum value of the lift for the given profile cannot be calculated and the rudder area is therefore not fully utilized.

By the increase in the length, the rudder impact angle at which the maximum lift is produced is reduced, and due to this, this angle can be obtained by the given rudder with its normal swing angles, in which case the rudder area can then also be smaller so as to reduce the cost of material in the rudder and reduce the expense of installing the rudder on a ship.

Rudders of large length are however not used, due to difiiculties in construction. Below the stern of the ship, where the rudder is normally arranged, there is relatively little space, so that the use of high narrow rudders is not possible. Accordingly, also, rudders which are used on ocean-going cargo ships have a length of 1.5 to 2.0, while rudders on river ships have a length of even less than 1.0.

It is an object of the invention to provide an artificial increase in the rudder length, thus making possible a more economical planning of rudder systems on ships. This result is obtained in accordance with the invention by the entire elimination of the flow around the horizontal rudder edges of the water which flows fromthe high pressure zone to the low pressure zone, or else by increasing the path for the flow around these edges. The solution of this problem indicated consists in the so-called wall effect, which is based on the fact that when a rudder having a length rests with one edge against the fiat wall, it is imparted the same hydrodynamic characteristics as though its length were twice as great, i.e., x =2 This effect is obtained by eliminating the circulation of water around one of the rudder edges.

On the other hand, by providing the vertical rudder plate with horizontal Walls on both ends affords the possibility of considering such rudders as rudders having a length which is theoreticaly infinite. By the use of a wall fastened to the rudder edge, the flow is impeded, and in this way the pressure equalization on the two sides of the rudder is delayed. If therefore, in the case of a normal or conventional rudder, horizontal surfaces or Walls of flat or drop-shaped cross-section are fastened to both the top and bottom edges of the vertical rudder plate, the effective length of the rudder is artificially increased. The new length of the rudder can be calculated by assuming that the new height of the rudder amounts approximately to the following H=h +0.8 (h +h in which I1 is the construction height of the rudder plate, h the width of the lower surface and h the width of the upper surface. The effect can be further increased by 3 producing on the horizontal surfaces or walls disposed on the top and bottom edges of the rudder plate a pressure difference which causes flow around the edges of these horizontal surfaces or walls themselves but which flow is in a direction opposite to the direction of the flow around the rudder plate. The pressure differences are produced on the horizontal surfaces or walls when they are set up at an angle to the oncoming stream of water.

Various other objects and advantages of the present invention will be readily apparent from the following detailed description when considered in connection with the accompanying drawing forming a part thereof, and in which:

FIG. 1 is a schematic sideview of the rudder of the present invention;

FIG. 2 a section through the rudder taken along the line 2-2 of FIG. 1;

FIG. 3 a section through the rudder taken along the line 33 of FIG. 1;

FIG. 4 is a side elevational view of a modified embodiment of the rudder shown in FIG. 1;

FIG. 5 a vertical section through the rudder taken along the line 5-5 of FIG. 4, and

FIG. '6 a section through an alternate embodiment of the rudder taken along the line 66 of FIG. 4.

Referring to FIG. 1, the lower and upper edges of the vertical rudder plate 1, have secured thereto horizontal surfaces or walls or plate members 2 and 3 which can have any desired longitudinal configuration or shape, for instance rectangular or streamlined, symmetrical or asymmetrical. The'shape of the overall plate can also be of any desired shape, for instance rectangular.

The horizontal surfaces 2 and 3 can be disposed substantially horizontal or as already described they can be disposed at a certain angle with the vertical rudder axis or to its plane of symmetry.

There can also be used a surface or wall with a structure having the upper surface 3 fastened to the ships body as shown in FIG. 4. In the case of this solution, the upper surface 3' is fastened to the ships body 5 by a vertical plate 4 which entirely eliminates the flow over the upper edge of the rudder. This structure provides the full wall effect, due to which the theoretical rudder length of the plate 1, even without the lower surface 2', will have twice as large a value as the actual length. In this embodiment, the upper or top edge of rudder plate 1 is disposed substantially contiguous to the fixed upper surface 3 so as to prevent flow of water therebetween while still not interfering with turning of the rudder. Other solutions of the devices which extend the flow path around the rudder edge and thus artificially increase the length of the rudder profile can also be used.

Other configurations for the rudder walls or surfaces can also be used in the shape of a cigar, with a round or an elliptical shape in cross-section, or of any other de- 4 sired shape fastened to the top and bottom edges of the plate, or to the ships body.

The additional surfaces serve furthermore as devices to protect the rudder against impacts from blocks of ice when the ship is traveling in ice fields. The frontal resis tance which is produced when using additional surfaces in accordance with the invention can be disregarded as its effect is negligible when compared with the total resistance of the ship.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. A steering rudder for a vessel and ship and the like comprising a vertical rudder plate having upper and lower edge, and a wall section disposed adjacent one of said edges for eliminating the flow of water around said edge from one side of the vertical plate to the other side thereof, said wall plate being adapted to be fixed to the body of the ship to which the rudder plate is attached.

2. A steering rudder for a boat, vessel, ship and the like comprising a substantially vertical rudder plate having upper and lower edge and substantially horizontally extending surfaces disposed adjacent said edges and extending substantially along the opposite sides of said vertical plate to prevent the flow of water from one side of said vertical plate to its opposite side, one of said sur faces being secured to the lower edge of the rudder plate and the surfaces disposed adjacent the upper edge being adapted to be secured to the body of the ship to which the rudder plate is connected.

3. A steering rudder for a boat, vessel, ship and the like comprising a substantially Vertical rudder plate having an upper and lower edge, and substantially horizontally extending surfaces disposed adjacent said edges and extending substantially beyond opposite sides of said vertical plate to its opposite side, said surfaces being secured to said upper and lower edge and extending substantially beyond the leading and trailing edges of said rudder plate.

4. The rudder of claim -1 whereinsaid wall member is disposed nonsymmetrically with respect to the vertical axis of said rudder plate.

References Cited by theExaminer UNITED STATES PATENTS 3,040,694 6/1962 Cochran ,114-162.X

MILTON BUCHLER, Primary Examiner.

ANDREW H. FARRELL, FERGUS .S. MIDDLETON,

Examiners.

Claims (1)

1. A STEERING RUDDER FOR A VESSEL AND SHIP AND THE LIKE COMPRISING A VERTICAL RUDDER PLATE HAVING UPPER AND LOWER EDGE, AND A WALL SECTION DISPOSED ADJACENT ONE OF SAID EDGES FOR ELIMINATING THE FLOW OF WATER AROUND SAID EDGE FROM ONE SIDE OF THE VERTICAL PLATE TO THE OTHER SIDE THEREOF, SAID WALL PLATE BEING ADAPTED TO BE FIXED TO THE BODY OF THE SHIP TO WHICH THE RUDDER PLATE IS ATTACHED.

Images