Reversible Camber Wingsail With Rotating Ribs for Low-Drag Tacking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cambered wingsails struggle with asymmetrical shapes that limit their ability to efficiently reverse camber for tacking, leading to high drag and reduced versatility in sailing applications.
Innovation Solution
A reversible camber wingsail design featuring a spanwise axis with rotatable rib units and a spar, allowing the sailcloth to form high lift airfoil shapes with opposite cambers by rotating rib units about an axis of rotation, and a cam mechanism to extend or retract rib units for tensioning or relaxing the sailcloth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a cambered airfoil shape is used to generate high lift, then aerodynamic efficiency is improved, but the ability to reverse camber for tacking is worsened
Solution Approach 1:
The wingsail is divided into multiple independent rib units that can be rotated individually or in groups about their axes. This segmentation allows different portions of the airfoil to change camber independently, enabling the sail to transition between high-lift configurations for power and reversed camber configurations for tacking, thus resolving the contradiction between maintaining aerodynamic efficiency and achieving camber reversal capability
Solution Approach 2:
The rib units are designed to be rotatable about their axes, transforming the static cambered airfoil into a dynamic structure. This dynamic capability allows the wingsail to adjust its camber in real-time, switching between optimized high-lift shapes for sailing downwind and reversed camber shapes for tacking upwind, thereby maintaining aerodynamic efficiency across different sailing conditions
2Ease of operation
If conventional flexible sails are used to reverse camber easily, then ease of operation is improved, but aerodynamic efficiency is worsened due to high drag
Solution Approach 1:
By segmenting the sail into rigid rib units with defined airfoil cross-sections, the design maintains the ease of camber reversal through mechanical rotation while preventing the fabric flapping and shape instability that cause drag in conventional flexible sails. Each rib unit's rigid structure ensures smooth airflow and consistent aerodynamic performance during reversal
Solution Approach 2:
The patent replaces the purely flexible mechanical system of conventional sails with a semi-rigid system incorporating rotatable rib units. This substitution provides controlled, predictable camber reversal through mechanical rotation rather than relying on fabric flexibility alone, reducing drag while maintaining ease of operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient sail adjustment for both port and starboard winds, reducing drag and enhancing sailing performance by maintaining high lift and low drag airfoil shapes.
Implementation Method 1
Each rib unit is configured to define a high lift airfoil profile in the respective rib plane. The high lift airfoil profile includes an aerodynamic lower profile edge and an aerodynamic upper profile edge.
Implementation Method 2
This dual curvature creates a pressure differential as air flows over the surfaces at different velocities, thereby generating lift.
Data Source
AI summary
Disclosed is a sailboat with a reversible camber wingsail and an air rudder assembly. The wingsail is capable of forming first and second high lift airfoil shapes of opposite cambers, and a third neutral, uncambered airfoil shape that allows zero lift (weathervane) docking and storage. The wingsail tacks by reversing the camber of the wingsail and alternating between the two high lift, low drag airfoil shapes. The wingsail employs an adjustable internal framework of spars and rotatable ribs to selectively configure a sailcloth to define the first and second high lift, low drag airfoil shapes and a third neutral airfoil shape. The wingsail incorporates camber linkages and tensioning mechanisms to address complexities of reversing the camber of the airfoil formed by the sailcloth stretched around the framework. The wingsail is detachable from the boat.