초록 ▼

A low drag and high lift sail has a fabric skin suspended by an edge tension device able to control forward and trailing edge tension to tune and reverse the airfoil section. The fabric skin is double, with a windward and lee section of different curvatures giving the airfoil section thickness. The

A low drag and high lift sail has a fabric skin suspended by an edge tension device able to control forward and trailing edge tension to tune and reverse the airfoil section. The fabric skin is double, with a windward and lee section of different curvatures giving the airfoil section thickness. The sail is supported by a mast and a curved boom located between the two fabric sections and thus is out of the impinging air stream. The ends of the boom are used for the sail support, usually with an additional external spar or spars on the windward side. The mast includes a foot which is either fixed or attached by a universal joint to a craft for motive power.

대표청구항 ▼

A flexible wing sail capable of cross-wind performance, reversible with respect to direction of air flow across the sail, and equipped with internal spars, comprising: permanently windward and permanently leeward webs of flexible sheet material connected together at their edges and engaged there wit

A flexible wing sail capable of cross-wind performance, reversible with respect to direction of air flow across the sail, and equipped with internal spars, comprising: permanently windward and permanently leeward webs of flexible sheet material connected together at their edges and engaged there with tension strand means for extending said webs in wing sail form and for adjusting the airfoil profile to the reversible direction of air flow, said leeward web being of greater extent than said windward web in the general reversible direction of intended wind flow along the sail, so as to facilitate formation of an airfoil section having substantial thickness at its mid-portion; and spar means for supporting said tension strand means, said spar means including a mast and a leewardly convex curved boom adjacently crossing each other in the space between said webs and running at least for most of their respective lengths between said webs, said tension strand means being supported at or near opposite ends of said mast and of said boom.