GB1173335A - Automatically stabilised hydrofoil boat - Google Patents

Abstract

1,173,335. Hydrofoil craft. SUPRAMAR A.G. 6 Feb., 1967 [7 Feb., 1966], No. 5625/67. Heading B7A. In a hydrofoil craft, rolling and pitching is minimized by atmospheric air issuing from a plurality of openings 8v, 8h, Fig. 2a, formed in the uppermost surface of a horizontal hydrofoil 2 that is attached to the stern of the hull 1, Fig. 2, by a vertical hollow member or support 4 resembling a rudder, said air being directed to said openings through said member and ducts 9v, 9h that are controlled by valves 10 situated at the lowermost end of said member and regulated by controlling means 11 in accordance with the rolling and/or pitching motion of the craft. The air is drawn through said openings as a consequence of the pressure reduction effected on the uppermost side of the hydrofoil when the craft is in motion, the flow of air across said side of the foil causing a reduction in the lift. Preferably, the hydrofoil 2 and a further hydrofoil 3, Fig. 1, adjacent the bow are designed such that the craft is normally in neutral equilibrium, stability being effected by suitably regulating the flow of air through the openings aforesaid. The hydrofoil 3 may include two lateral upwardly-inclined portions, Fig. 3 (not shown), and a horizontal portion 3m, Fig. 1, therebetween. The lift produced by the hydrofoil 3 may be controlled by an arrangement similar to that provided for the hydrofoil 2, the openings being situated in the portion 3m to which openings air is directed through a central hollow support (5). Rolling may be also minimized by providing air ducts and openings in the said support, Fig. 3b (not shown), the arrangement being again similar to that provided for the hydrofoil 2 so that openings are furnished on both sides of the support below the water line. The hydrofoil 3 may be modified, Figs. 4 and 4a (not shown), the support (5) being replaced by two lateral supports (6) having extensions (13) projecting below the hydrofoil and containing air ducts and openings similar to those in the support (5). The portion 3m may have either a V- shaped or an inverted V-shaped profile to improve the stability of the craft. The member 4 may be replaced by two parallel rudder-like members or supports (4a, 4b), Figs. 5 and 5a (not shown), which are similar to the said member. Each of the valves 10 may be operated by a cam (18v), Fig. 6a (not shown), which in turn is actuated by a gyroscope (21) and a pendulum (23) responsive to rolling and pitching and to static angular displacement and acceleration of the craft, respectively, the combined output signals of the gyroscope and pendulum being transmitted to the cam through a pneumatic intensifier or amplifier (27). The gyroscope and pendulum constitute the controlling means 11. The hydrofoil 3 may have supports (7), Fig. 4, attached to a horizontal shaft (15) coupled to an hydraulic motor so that the angle of attack of the hydrofoil can be regulated by the helmsman. Provision may also be made for manual operation of the valves 10 associated with the portion 3m of the hydrofoil 3 by the helmsman so that the lift effected thereby can be varied. Alternatively, the portion 3m may have a pivotable flap 14, Fig. 1, at the trailing edge thereof, which flap can be controlled by the helmsman so as to adjust the lift.