a glob of nerdishness

May 8, 2007

Rotating cylinder lift

written by natevw @ 9:17 pm

Did you know a rotating cylinder can generate lift? It’s not very efficient, but it has been used to propel a ship across the Atlantic. I learned this strange bit of trivia through an electrical engineering friend who is now a broadcast radio technician. Spending time climbing to the tips of tall radio towers on a regular basis, I guess any source of lift is just cause for excitement.

Lift of a Rotating Cylinder on a NASA education page has the real skinny, but from what I gather (and correct me if I’m wrong) the cylinder needs to be moving “into the wind”, relatively speaking. The key is that the moving surface of the cylinder tends to drag some air along with it. If the bottom is moving against the oncoming stream, it will be slowing the air below while the top stream is helped along. Slower on the bottom, faster up top? Mix in a little Bernoulli and it’s up and away!

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