Friday, June 17, 2011
Maple "Helicopter" Seeds
"Whirlygig" maple seeds from a tree in my yard.
According to NASA, "Autorotation takes place because of the asymmetrical nature of maple seeds (and of paper copies). The center of mass of the seed is shifted well to one end while its center of lift is approximately in the middle. In a complicated process, the forces at work as the seed falls combine to begin a circular rotation of the seed about its center of mass. The rotation actually inscribes a cone around the axis of fall. The shape of the cone will vary depending upon the aerodynamic qualities of the seed's blade (wing). A blade with minimal lift properties will inscribe a steep-side cone while a blade with strong lift properties will inscribe a very flattened cone."
(And hey, there's another bonus bug that wasn't visible when taking the picture! Everybody take a drink!)