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

[0009]In this regard, the present invention provides for a three dimensional rigid foil sail design. As such, the general purpose of the present invention, which will be described subsequently in greater detail, is to provide at least a three part rigid foil sail having a full length vertical leading edge whose trim angle / angle of attack is controlled by the main sheet and at least two 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.

[0010]The design of the rigid foil sail of the present invention 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. Such an arrangement allows the boat to be driven without the loss of upwind pointing performance and without the loss of power caused by luffing of the sail. Similarly, the boat can be better balanced by trimming the lower trailing flap for optimum performance and simultaneously trimming the upper trailing flap neutral or even to leeward to create an opposing force that will counter the heeling moment of the sail allowing the boat to be driven to windward more efficiently with a minimum heel angle.

[0011]Therefore, it is an object of the present invention to provide a rigid foil sail that has adjustable camber that is also capable of being detuned to allow its use in heavier wind conditions. It is a further object of the present invention to provide a self-supporting rigid foil sail that includes adjustable camber to increase or decrease the power generated by the foil shape. It is still a further object of the present invention to provide a rigid foil sail that includes at least two adjustable trailing sections to allow independent adjustment of the sail camber in a manner that better balances the boat without compromising upwind pointing performance.

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