WingMills: Harvesting by Unsteady-Aerodynamics and Dynamic-Stall

WingMills are an exotic WECS archetype with few research precedents. Their self-oscillating unsteady-aerodynamics, of flapping cycles with double dynamic-stall phases, indeed pack a punch. This is the applied principle of the famous “how a bumblebee flies”, deadly “flogging-jibs”, and what brought down the Tacoma Narrows Bridge. WingMills are closely related to or part of specific kite energy schemes (Airborne Wind Energy, AWE), and ideal for direct kinetic pumping work. High power-to-mass and low-CapEx are exceptional inherent advantages.

KiteLab Ilwaco and kPower of Austin have designed, built, and tested many WindMills at small scale since 2007, as a conceptual spin-off of low-complexity passive-dynamic (aka dynamic-stability) Airborne Wind Energy R&D. These simple fabric wings, with a few battens embedded, are a cheap, effective, and novel form of wind energy. Here is an action video of a WingMill of about 1m2 and 200g, at ground level, in a fresh breeze, producing a 12V battery-charging output of ~8A (~100W). Renewable energy without tower, sun, or complex control.

Dave I don’t get it this what is the point, you offer these???

Hi Brent,

The goal here is to explore novel Airborne Wind Energy (AWE) harvesting by unsteady aerodynamics, at possibly highest power-to-mass and power-to-CAPEX. Sadly, the market is too small for wind novelties like these to support serious AWE research. An experimenter has to make their own versions, and is paid in knowledge.

Here is another experiment, actually flying. The Wingmill is ~100cm2 and the lifter kite ~700cm2. Such a combo could cost 10USD and put out ~25W in a nice breeze.

The best AWE concepts and subscale prototypes are hoped to soon lead to utility scale plants. Imagine a 1000M2 WingMill producing ~10MW in superior wind about 500m high. Imagine 100 such unit-WingMills in a single-plant kite network powering a small city.

Another advantage to these may be automated high-speed (>10m/sec) production from polymer roll-stock, with almost no wastage. In principle, a single mega-factory could repower the world in a couple of years, recycling wings in a sustainable circular-economy. The subscale WingMill in the video was made from a simple sandwich of 5cm wide fiberglass-reinforced strapping tape, with a tail made from a plastic bag.

Just will add this as source to this JMSE | Free Full-Text | Numerical Study of an Oscillating-Wing Wingmill for Ocean Current Energy Harvesting: Fluid-Solid-Body Interaction with Feedback Control for more info.