Adjusting rigid foil spar system

Abstract

A rigid foil sail having a full length vertical leading edge whose trim angle / angle of attack is controlled by the main sheet and trailing edge flaps attached rearwardly of the leading edge, each of which can be independently trimmed from a convenient deck level control tray to achieve easily adjustable camber. The design of the rigid foil sail allows depowering of the sail without altering mainsheet trim by decreasing the camber of the upper trailing flap thus also decreasing the heeling force created by the power of the upper trailing flap. Further, a void within the foil is filled with a lighter than air gas to assist in countering heeling moment to allow the boat to be driven without the loss of upwind pointing performance and without the loss of power and also allowing the boat to be driven to windward more efficiently with a minimum heel angle.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a Continuation in Part Application of U.S. patent application Ser. No. 13 / 180,633, filed Jul. 11, 2011, which is related to and claims priority from earlier filed U.S. Provisional Patent Application No. 61 / 483,996, filed May 9, 2011, the contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]The present invention relates generally to rigid foil sails for boats. More specifically, the present invention relates to a rigid foil sail system for boats that has independently controllable sections that allow optimum control over the lift force generated by the soil in varying wind conditions and directions.[0003]Although the appearance of the conventional sail is quite different from that of an aircraft wing, its function in generating a positive force is based on the same aerodynamic principles as those applied to a wing. The sail, however, is considerably the less efficient foil of the two p...

AI Technical Summary

Benefits of technology

The present invention provides a three-dimensional rigid foil sail design with adjustable camber. The design allows for easy and independent trimming of the upper and lower trailing flaps to achieve optimal performance and balance. It also allows for detunning in heavier wind conditions and increased or decreased power generation by adjusting the foil shape. The at least two adjustable trailing sections allow for independent adjustment of the sail camber without compromising upwind pointing performance. The design optimizes boat performance and increases efficiency in driving to windward.

Problems solved by technology

The sail, however, is considerably the less efficient foil of the two partly because the sail utilizes a single surface air foil as opposed to the more efficient double surface air foil of the wing.

Another factor that reduces the efficiency of a conventional sail is that its external bracing, mast and rigging disturb the flow of air around its surface, resulting in an energy loss to turbulence and drag.

Despite its much greater efficiency, a standard wing does not make a good sail when mounted in a vertical position so that the lift that it generates can be used as thrust to drive a boat or vehicle.

A close review of the prior art in this area reveals that the design and construction of such variable camber wings have been complex and in fact impractical when considered on a commercial production basis.

It has, however, a fault in that it is difficult to handle and troublesome to lower.

Further, the airfoil shape of the sail can only be achieved effectively with the various segments fully extended vertically.

Further shortcomings originate from the excessively complicated construction of the sail, which is also the cause for high cost and low reliability.

Finally, such sail arrangements are generally heavy.

Should the vessel overturn the prior art rigid sails risk filling with water, compromising both the floatation of the sail and the boat.

Images