GB774854A - Improvements relating to hydrofoil-equipped water-craft - Google Patents

Abstract

774,854. Hydrofoil craft. SUPRAMAR AKT.-GES. Aug. 30, 1955, No. 24912/55. Class 113. In an arrangement for automatically controlling the lift of hydrofoils, the hydrofoils are vertically displaceable and an elastic element maintains the equilibrium of the lifting force in such manner that the hydrofoils, under the disturbing impulses acting on them when passing through waves, perform oscillations relatively to the hull and these oscillations act to control the adjustment of the pitch of the hydrofoils or pivotable flaps provided at the trailing edges thereof, the arrangement being such that the phase of the controlled alterations in lift at the hydrofoils is displaceable relatively to the phase of the control oscillations transmitted in accordance with the length of the waves. The hydrofoil 1 is attached to a frame 2 on a support 3 forming an assembly suspended on a shaft 4 from a lever 5 pivotally mounted at 6 to the boat. The hydrodynamic lifting force is balanced by an elastic element 9, which in Fig. 1 acts on the longer arm of the lever 5 and can have its tension modified by a hydraulic device 10, but could be located above the support 3 as shown at 9a, or could be a torsion spring on the axis 6 as in Fig. la. The hydrofoil assembly has a second link pivoted to the boat, namely an hydraulic device 7 connected to a part 8 of the support 3, so that the assembly is able to carry out free vertical movements. The oscillating movements are received at the lever 5 and transmitted through a rod 11 to an adjustable control device 12 which may be a time-delay relay, an impulse storage device, an electric or hydraulic phase-shifting device, a combination of resonance circuits, or one of the devices described in the Specification. From the device 12 the movements are transmitted with a phase displacement by a receiver element 13 to the valve 14 of the hydraulic device 14 which rocks the hydrofoil assembly about the axis of suspension 4 to change the pitch. In Fig. 1a the hydraulic device 7 actuates a pivoted flap 1a on the hydrofoil 1 and is connected to a second hydraulic device 15 controlled by the valve 14. Specification 745,821 is referred to.