Jack wrote; >Another way to think of it is that aircraft like sailplanes --- gliders --- >have very high aspect ratio wings, long and thin, as does the U-2 >spy plane; can go high, stay high with little fuel expended. Not >fast, but tremendous endurance. Like the Greenland paddle. And >then there's helicopters --- long, thin wings that you whip around >over your head --- on your rotorhead, that is --- to achieve lift. Not >fast, but surprisingly efficient. Igor Sikorsky called it a rotating >wing assembly, and Sikorsky drawings still refer to it in this term. >Fascinating, huh? And all this based on Greenland paddles! One has to use care when applying this kind of thing. For example, gliders require high lift but low drag. The use of paddles more closely resembles sailing on a broad reach where one wants to maximize thrust. In so doing one seeks to optimize both drag and lift components in which case a lower aspect ratio paddle ala the racing wing paddle has greater efficiency. This all ignores the further complication of wave making. Applying the helicopter rotor also falls short since they work as high speed lifting foils. The low speed, low load ship propellor fits the paddling model more accurately. One can see the differences in applicatioin by comparing high speed ship propellors and low speed ship propellors. High speed propellors generally have higher aspect ratios. Mind, super cavitating propellors alter circumstances but not many paddlers I know can cause supercavitation with a paddle and I sure wouldn't want to tick a person off that could. :-) In any case, I don't think the high aspect ratio paddles of the Arctic influenced either since the objectives differ so much. Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ Actually, I was hoping Professor Inverbon might have some interesting etymological information on the derivative of the word "Toksook". Jack Martin *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************Received on Wed Apr 07 1999 - 07:32:55 PDT
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