John Winters wrote: >I suspect that a lot of the confusion comes from assuming the objective is high lift as opposed to high thrust per unit area. If we change the question from How do we generate more lift? to How do we generate more thrust we may get another answer. Why are you assuming that the important objective is high thrust per unit area? I think there is another element that is more important perhaps than thrust per unit area. I can not see how thrust per unit area is even relevant to what is important to a paddler. I would think that for long distance paddling what you want to measure and optimize is thrust output per power input (the power input is the work rate of the paddler's muscles), this would yield the maximum distance for a given available energy. For a racer you would want to measure and maximize thrust output per force input (at the shaft), this would yield the maximum speed for a given paddler's strength. The maximum thrust that can be generated from a given blade size is not necessarily the most efficient paddle, efficiency has to be measured as energy in vs. energy out, or more accurately thrust output vs. work input. An aircraft analogy is Short Take-off and Landing airplanes (STOL). The wings are shaped to generate high lift per unit area, at the expense of a very draggy wing design in normal cruise (higher speed) mode. The highest lift per unit area on a wing yields a very slow and inefficient aircraft. The most efficient aircraft do not have high lift wings, but rather high L/D (or lift to drag ratio) wings. Although the area of the blade may be indirectly related to these things, ISTM that if you do not establish the correct measurements you will end up with meaningless results. Peter *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 14 Sep 2004 at 20:40, Peter Chopelas wrote: > efficiency has to be measured > as energy in vs. energy out, One measure of efficiency is energy in vs out. There can be other efficiencies measured. > or more accurately thrust output vs. work input. One's a vector, the other's a scalor; the units of measure don't match. You're were better off with energy in and out. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Peter wrote: > > or more accurately thrust output vs. work input. To which Michael Daly" <mikedaly_at_magma.ca> replied: > One's a vector, the other's a scalor; the units of measure don't > match. You're were better off with energy in and out. True, they usually refer to different things: one is a force, and the other is a work unit. I wonder if Peter is using "thrust" in some different way than what I have normally seen. Can "thrust" refer to foot-pounds? I always thought it meant force. Maybe Peter can clear this up. I think the comparison to make might be the work the paddle does on the water (how in heck you would measure that, I don't know) compared to the work input by the paddler on the paddle. I bet the former is what Peter means by "thrust." I agree with Peter's suggestion that monitoring (and normalizing) a paddler's respiratory demand is perhaps a decent way to eliminate or reduce differences in real effort by the paddler. -- Dave Kruger *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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