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KBBS Archive 00,000
Re: integral rudder...again
Posted By: Mark Kanzler In Response To: Re: integral rudder...again (Nolan Penney)
Date: Saturday, 29 August 1998, at 10:55 a.m.
I'd have to disagree. As the aspect ratio gets lower and lower, the wing behaves less like an airfoil. Airfoil, by (aerodynamicists) definition is infinitely long (infinite span), and is therefore only subject to 2D flow. A wing is not an airfoil, and vice versa. In wind tunnels, the airfoil usually spans the tunnel and attaches at the walls. This is stil imperfect because where the wing joins the wall there is some interference, but data is taken at midspan when airfoil data is desired. When wing data is desired, the data is taken in "strips" along the span (sort of a checkerboard pattern of pressure ports and/or tufts)
The aspect ratio of a kayak (span / chord) is about .05, where on an airplane it's around 10 nominally. The flow around a kayak does not go from bow to stern directly, it flow upward as well.
This is not to sat that there are no airfoil effects, only that there are many other flow effects that make predicting hoe thw shape as viewed from above will effect the outcome, and corollation to airfoil data is certainly not the way to go.
A kayak is shaped more like a wingtip than like a section cut out of a wing. Because of this and its shortness in the spanwise direction (beam), I would not expect it to behave in a simple manner.
I really enjoyed the golfball article, Bill Nye is one of my all time heros. He brings science to kids in a way that is fun and understandable. When I was a kid, I was wierd because I really enjoyed science classes. I enjoyed doing experiments at home, especially where boats, airplanes, or pyrotechnics were involved.
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KBBS Archive 00,000 is maintained by Nick Schade - Guillemot Kayaks with WebBBS 5.12.
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