What is "tumblewing"

A tumblewing or "tumble wing" or "tumbling wing" is a glider or kite wing design which rotates about an axis traverse to the apparent wind, not necessarily horizontal. Notice the tumble wings in massive confetti tosses; the tumbling wings become visually exciting at celebrations. Tumble wings are frequently employed in wind turbines (type Savonius wind turbine). Tumble wings may be made of any material that supports some stiffness for form: paper, plastic, metal, composites, leaves, wood, etc. Many leaves falling from trees become tumble wing gliders. Its mode of flight is more akin to confetti than traditional fixed-wing aircraft; However, several model aircraft (see flettner airplane) have been built with tumbling wings for lift (force). Tumbling wings generate lift by alternately flying and stalling as the angle of incidence changes with the spinning motion (see magnus effect and flettner rotor). Because it has no need for ballast, the tumblewing design has a lower wing loading and makes a good walkalong glider which is easy to make and fly. The first example of a tumblewing flown as a walkalong glider appears in the book Fantastic flight. The Big Mouth is another example of a tumblewing design which can be flown as a walkalong glider. Tumble wings are employed as the wing of kite systems, a type of rotary kite, e.g. the rotor kite of Stephen Wingert taught in patent US7621484, one of scores of such patents.