GB1052305A - - Google Patents

Abstract

1,052,305. Hydrofoil vessels. SUPRAMAR A.G. June 9, 1964, No. 23896/64. Heading B7A. Apparatus for automatically controlling the depth of hydrofoils 1 having at least one flap 2 hinged to the trailing edge of the hydrofoil comprises cylinder means 9 having a piston 11 therein interconnected with said flap 2, means for varying the pressure in the cylinder to move the piston and thus the flap so that the lift increases as the pressure decreases, the means including air ducts 5 connected with cylinder 9 having air intakes 6 disposed in positions above and below the normal water line when the watercraft is in motion for changing said pressure conditions applied to the piston in relation to changes in the level of the air intakes relative to the water surface and an air regulator valve 14 arranged between the control means and the cylinder 9 for variably restricting communication of air from said control means to the cylinder 9 and for admitting additional air to said cylinder. As shown, flow of water past suction openings 8 in strut 4 creates a subpressure which is communicated via channels 7, 7a to piston 11 which moves downwards and thus moves flap 2 in an anticlockwise direction. Cylinder space 10 is also in communication with ducts 5 and air intakes 6. Air is sucked in through intakes 6 and decreases the subpressure in cylinder space 10. The amount of air sucked in will depend on the depth of the strut 4, i.e. the number of intakes 6 above water level. The air is regulated by a valve 14 which can block certain of the ducts 5 or increase the air intake via slit 17. Valve 14 can be automatically regulated through control devices which react to movement of the watercraft at sea, e.g. gyroscopes and accelerometers. Air can be directed to the top surface of the hydrofoil (Figs. 3 and 4, not shown) to influence the lift of the foil.