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Handheld Wing Sail (March 2025)
Handheld Wing Sail (March 2025)
Overview
Overview
Designed and prototyped a lightweight, handheld wing sail designed to propel a skateboarder, providing an alternative land-based wind sport during the winter months when water sports are inaccessible.
Preliminary Requirements
Preliminary Requirements
Rigid Wing Construction: Prioritized a rigid frame over inflatable structures, which are highly susceptible to puncture and wear on abrasive land surfaces (asphalt/concrete).
Passive Aerodynamic Stability: Optimized the wing geometry for intuitive, stable handling to ensure the rider can maintain control while actively balancing on a skateboard.
Target Sail Area (3-4 m2): Balanced the low rolling resistance of a skateboard against potential terrain challenges (e.g., inclines, headwinds). A larger surface area offers greater operational flexibility across variable weather conditions.
Strict Constraints: Heavy focus on minimizing overall weight for user endurance and maintaining a low-cost, accessible budget.
Material Selection & Component Design
Material Selection & Component Design
Handle (1" Carbon Fiber Paddle Shaft): Repurposed component providing a high strength-to-weight ratio with an ergonomic diameter for prolonged grip comfort.
Frame (PEX Piping): Chosen for its excellent impact resistance, affordability, availability, and ease of cold-forming or manual manipulation.
Connectors (3D-Printed PETG): Brackets were modeled in Autodesk Fusion 360 using Form Modeling and Generative Design to optimize load path efficiency and minimize printed mass. PETG was selected for superior layer adhesion and impact resistance compared to PLA.
Sail Skin (Heavy-Duty Polyethylene Tarp): Completely windproof, high tensile strength, and low mechanical stretch. Affordable and easy to cut.
Generativly Designed Front Bracket
Structural Framework Logic
Structural Framework Logic
The wing framework leverages varied material stiffness to achieve dynamic aerodynamic stability:
Leading Edge (¾” PEX): Provides a rigid structural spine and robust sail mounting surface. Concentrating mass forward optimizes the wing's center of gravity for better handling.
Center Chord (½” PEX): Holds the pre-bent curve of the leading edge. Its flexibility allows it to deform intentionally under wind load, forcing the wingtips outward to increase the dihedral angle for passive stability.
Sail Integration & Fabrication
Sail Integration & Fabrication
Leading Edge Attachment: Relief cuts were made along the perimeter of the tarp to allow the material to conform smoothly to the curved frame. The edge was folded over the ¾” PEX pipe and secured back to the sail using high-strength tape.
Aft Tensioning: The aft corner of the sail was anchored to the center chord terminus using the same wrap-and-tape method to establish baseline skin tension.
Free Trailing Edge: The trailing edge was left completely unsupported. This mirrors conventional windsurf and wing-foil geometry, allowing the sail to twist and spill excess wind efficiently.
Completed Frame on Tarp
Performance Results & Iteration
Performance Results & Iteration
Velocity & Power: The prototype performed exceptionally well, successfully propelling a rider up to speeds of 25+ mph in approximately 20 mph winds.
Durability: The material selection proved highly robust for land-based use. Despite significant runtime and multiple high-impact crashes on asphalt, the wing sustained only minor cosmetic damage, validating the choice of PEX and PETG.
Design Iteration: Operational testing revealed that the initial ½” PEX center chord was overly flexible under heavy loads, inducing unpredictable sail luffing (flapping) in high winds. This was successfully resolved by replacing the center chord with a slightly longer ¾” PEX pipe, which stabilized the sail shape and eliminated the luffing while maintaining excellent handling.
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