„Aerodynamical Intelligent Stabilizer“ - AIST
principle of the Aerodynamic Intelligent Stabilizer – AIST
- AIST is an aerodynamic aerofoil, which is attached to the masthead by hinges. The hinges permit an angular movement relative to the three perpendicular axes. By means of a manual or automatic control the aerofoil orientates itself in the horizontal plane, independently of the angular position of the sail boat and its mast, and with the maximum possible angle of attack to the relative wind speed. Acting through the hinges on the mast like on a lever, the aerofoil produces an aerodynamic righting moment and counteracts the heel. The lift is proportional to the square of the relative wind speed and the heeling angle.
- Dimensions of the stabilizer depend upon the design features of the sail boat such as the height of the mast, the sail area and the aerodynamic efficiency of the aerofoil.
- In many respects, the operation principle of the AIST-system is alike an aircraft tail plane.
Advantages of AIST
The aerodynamic stabilizer allows:
- The value of the aerodynamic righting moment is proportional to the
square of the air flow velocity and to the angle of yacht heeling. It
enables to design a sail boat which could reach a record high speed
and even plane at a close-hauled course.
- The AIST-system increases the transverse stability of a conventional keel boat with increasing relative wind substantially, without virtually changing the sail boat weight. The combined action of AIST and the ballast makes it possible to decrease the heel angle of the boat, which results in a a greater driving force, and a reduction of the hydrodynamic resistance. Both factors increase the speed of the boat.
- AIST enhances the dynamic characteristics of the boat, and allows to get a better acceleration and braking performance.
- AIST improves the sailing comfort.
- AIST can be implemented practically for all types of sail boats (dinghies, keel boats) with an experienced or unexperienced crew, simple or extreme sailing conditions
- AIST works at all wind speed including storms, for all rig types and even in the absence of sails
- AIST counteracts the roll motion of the sail boat relative to the
longitudinal axis at courses with the wind aft, caused by asymmetrical
stalling flow around the sails. It prevents, especially with the wind
aft, the roll, the yawing and the knockdown of the sail boat.