The present invention relates to a two-way slotted rudder for fluid-dynamic application, in particular aerodynamic application, comprising a carrier element attached to a vehicle or aircraft and having carrier surfaces, in relation to which a rudder element is attached to be rotatable around a first shaft rigidly attached to the vehicle or aircraft. There are various applications of such controls, in particular within the aerodynamic and hydrodynamic field. For aircraft, it can for example apply to side rudders or ailerons.

Considering the increasing costs of motor fuels one tries to obtain such a con¬ figuration of aircraft and vehicles that said costs will be as low as possible. The de¬ sign of rudder elements has importance thereto. The object of the present invention is to provide a two-way slotted rudder of the kind mentioned in the beginning which provides a good control function, which has a minimum power consumption and which is relatively simple as to its structure.

According to the invention such a two-way slotted rudder is characterized primarily in that on each side of a first chord plane through the carrier element a first door is arranged, which is a rotatable about a second shaft at the carrier element, the first door being arranged to connect, with its edge facing away from said second shaft, to the surface of the rudder element, when a second chord plane through the rudder element is parallel to the first chord plane or forms an angle a thereto in a direction towards said first door, and that it forms, at said edge, when said angle is formed in a direction away from said first door, a slot together with the rudder element, a second door being arranged to be rotatable about a third shaft and opening a window in the first door, when the angle a is formed in a direction towards said first door, so that a flow path for the fluid is formed from the pressure side of the rudder element to the suction side thereof.

In an advantageous embodiment of the two-way slotted rudder the extension of this slot in a plane perpendicular to the first and second chord planes constitutes 0.3% to 3% of a total chord length of the carrier element and the rudder element. The ex¬ tension of the slot constitutes then advantageously about 1.5% of said total chord length.

The extension of the slot in parallel to the first and second chord planes is not

critical but constitutes suitably up to about 80% of the extension of the rudder element (2) in parallel to the these planes.

The invention will be described in the following with reference to the accompanying schematic drawings which are related to the use in an aircraft, in which:

Fig. 1A shows a view of a cross section through a two-way slotted rudder according to the invention,

Figs. IB - IE show alternative designs of a detail of the object in Fig. 1A, and

Fig. 2 shows a view of a cross section of a portion of an alternative embodiment of the object of Fig. 1A.

In the figures a carrier element, which has carrier surfaces and is rigidly attached to a vehicle or aircraft, such as a wing or fin, is denoted by 1. A rudder element 2 is attached to be eccentrically rotatable about a first shaft 3, which is rigidly attached to the vehicle or aircraft. On each side of a first chord plane 4 through the carrier element 1 a first door is arranged, denoted by 5 and 6. These doors are each arranged to be rotatable about a rotatable second shaft 7 and 8 close to the carrier element. Each second door is arranged to connect, with its edge 9 and 10 respectively, facing away from its second shaft, to the surface of the rudder element, in the case where the second chord plane 11 through the rudder element is located in parallel to the first chord plane 4, the two-way slotted rudder then being arranged in a neutral position, or where it forms an angle thereto in a direction towards said first door. It forms at said edge 9 or 10 together with the rudder element a slot 12, in the case where said angle a is formed in a direction away from said door. In each of the first doors a second door, denoted by 13 and 14, is arranged to be rotatable about the second shaft 7 and 8 and forms a window 15 and 16 in the first door in the case where the angle a is formed in a direction towards said first door, so that a flow path, denoted by 17, as is apparent from Fig. 2, is formed for the air.

As appears from Figs. IB - IE the second doors 13 and 14 can also (as is illustrated in the figures) be arranged to be rotatable about separate third shafts 30 - 33, which are located at a distance from the second shaft 8. In Fig. IE a variant is shown in which the door 14 is carried by a link 34 that is rotatable about a third shaft 33.

Fig. 1 relates to a two-way slotted rudder having an asymmetric carrier element and an asymmetric rudder element. The slot 2 constitutes in the example illustrated about 1.4% of the total chord length of the two-way slotted rudder, which is suitable.

The desired function can be obtained in different ways, either in a purely mechanical way, comprising control discs and link systems, or electron ydraulically, or a com¬ bination of these two systems. In Fig. 2 parts of a mechanical control system are schematically indicated. A control disc 18 is attached to be rotatable about a third shaft 19 and controls the rotation of the rudder element 2 through links, not shown. In the first doors two control arms 20 and 21 are attached which are guided by tracks 22 and 23 in the rudder element. Said control disc 18 is provided with two guide tracks 24 and 25, which act on pivotable links 26, 27, 28 and 29 in order to control the movements of the second doors 13 and 14.