Talk:Sail
From Academic Kids
Something to clarify: No sail has any bits of engine or motor? --Menchi 02:32 8 Jun 2003 (UTC)
- Flettner rotors (I may not have that spelled right) do have motors, but they are rarely used on purely sailing vessels. The are found (when found at all) on hybrid motor/sailing vessels that use the windpower to increase efficiency. The rotors work much like a golf ball; they are cylinders with a dimpled surface that is rotated at high speed. As the wind passes across the moving surface, the side going with the wind pulls the air further than the side going against the wind, which generates lift at 90 degrees to the wind. Reverse the direction of rotation, and you reverse the direction of lift. I don't know that any energy is lost (other than normal frictional losses) when generating the lift; if there is no additional energy loss, then the motor is not putting any energy into the generation of lift, and you coud consider the rotors to be "pure" sails. scot 14:09, 22 Apr 2005 (UTC)
