The Boeing Company

Kenneth R Meldahl

Gary J Warner

Robert J Gornstein

An improved leading edge contour for control flaps of the type suitable for use with hydrofoil vessels and the like wherein discontinuities or gaps between the leading edge of the flap and the trailing edge of the fluid foil to which it is attached are held to a minimum; yet, wherein localized or discontinuous differential deflection of the flap leading edge and the foil trailing edge, which inherently occurs as the vessel moves through a fluid medium, does not result in interference between the two edges, thereby minimizing the problem of reduced fatigue life; and, wherein excessively large discontinuities are not required between the two edges in those edge areas where no significant differential deflection occurs, thereby significantly improving the performance characteristics of both the flap and the flap/foil combination. More specifically, an improved flap leading edge construction wherein the distance between the flap leading edge and the foil trailing edge is maintained at a desired minimum, or optimized, gap space in those regions where the flap leading edge is positively, yet hingedly, connected to the foil trailing edge--i.e., those points of 'hard' connection--while that region of the flap leading edge intermediate such hinged 'hard' connection points--i.e., regions of 'soft' or non-positive connection--define a slightly greater gap or discontinuity with the foil trailing edge, thereby permitting greater differential deflection of the two edges in those regions of 'soft' or non-positive connection where the flap is generally subjected to deflection of greater magnitude than is the foil; yet wherein the foil trailing edge can be simply machined as a radius at constant percent of chord over the entire span of the foil.

Flap leading edge for hydrofoil vessels and the like

A method of designing hydrodynamic sections having improved characteristics is described wherein a desired pressure profile and boundary layer conditions for the surface of an undefined section are established at operating velocities for the section and a hydrodynamic section is analytically designed to provide the desired characteristics. One preferred embodiment of the hydrodynamic section meeting the established pressure profile and boundary layer conditions is disclosed having a flat bottom and upper surface defined by a plurality of circular arcs.

Growing community of inventors

Bellevue, WA, United States of America

Kenneth R Meldahl