----- Original Message ----- From: Michael Orchard <mspadorchard_at_home.com> To: Peter A. Chopelas <pac_at_premier1.net> Sent: Sunday, May 20, 2001 8:50 AM Subject: Re: [Paddlewise] Apology for post about paddle efficiency > Peter, and or anyone else... > > I am fairly new to this list, and haven't taken physics for many years...but > enjoy both the technically accurrate and not so accurrate postings on this > topic of paddles and effieciency...one of the things I enjoy in a sense is > the mixture of backgrounds I see on the list...although I often have to > guess in my mind as to the technical background of a given poster... > > One thing I am still guessing at...What is a "high aspect ratio" > paddle...is this synonymous for a greenland style paddle, a long narrow paddle, a long narrow paddle canoe style padle...or ? sorry if this is elementry to all others, but I see it referred to > often here, but not defined, and it is not in my physics background. (I am > a veterinarian). > > thanks, > > Michael Orchard > > > This just demonstrates how important it is that everyone use words the same > > way, otherwise you can not communicate. It is especially unfortunate that > > recent trends have been to use fancy words improperly because it makes > > speech or prose appear more sophisticated. It is one of my pet peeves, > and > > really demonstrates lack of language skills, not sophistication. But it > > also leads to many unknowingly using words like "efficiency", "power", and > > "force" in inaccurate ways, and not to understand what these words really > > mean. > > > > All the best. > > > > Peter Chopelas > > > > > > > *************************************************************************** > > 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/ > > > *************************************************************************** > *************************************************************************** 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/ ***************************************************************************
I think I can demonstate with wings better than with paddles. Aspect ratio is the ratio of the length of the wing to the width (distance from leading edge to trailing edge) of the wing. Examples of high a-r: the long thin wings of a high-performance sailplane or a U-2 or an albatross. Example of low a-r: the short stubby wings of an F-104, a cruise missile, or of non-gliding birds like a hummingbird or a sparrow. ----- Original Message ----- From: Michael Orchard <mspadorchard_at_home.com> <snip> > One thing I am still guessing at...What is a "high aspect ratio" > paddle *************************************************************************** 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/ ***************************************************************************
Actually, i think that even a narrow, greenland style paddle needs not to have a high aspect ratio. The notion of aspect ratio only makes sense if the paddle is used in a wing-like way. If you pull the paddle backwards without anysideward movement, so the angle of attack is 90degrees, then the paddle does not know which dimension is the length and which is the width. So the greenlander mignt be an ultra-low aspect ratio paddle.... To my feeling most paddles (even greenlanders) are used at high angles of attack, so the flow is stalled. Peter is right in most of what he says, but I do not think all of his theory is necessarily valid in the post-stal region. The behaviour of wings or paddles in the post-stal region is rather different from the unstalled behaviour. A second point is that in comparing greenland paddles and euro paddles you have to take into account the airfoil. Greenlanders usually have a thick, symmetrical airfoil. These thick airfoils have gentle stall characteristics, quite different from the flat plate or hollow cambered sections of most euro style paddles. On the other hand a high aspect ratio wing (or paddle) does stall at a lower angle of attack than a low aspect ratio one. Is there anybody on the list who volunteers to putt a few woolen tufts on his greenland paddle? I really would like to know if greenland paddles are used with a stalled flow. For what it is worth, Greetings, Merijn ****************************** Merijn Wijnen Vinkenhofje 8 5613 CN Eindhoven The Netherlands Tel.: 040-2939991 (job: 040-2650539) Fax: same as tel., call before sending or try twice E-mail: Home: merijn_at_music.demon.nl Job: m.wijnen_at_ind.tno.nl Web-site: http://www.music.demon.nl *************************************************************************** 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/ ***************************************************************************
"Michael Orchard" wrote: } Subject: [Paddlewise] What really is a high aspect ration paddle? > > > > One thing I am still guessing at...What is a "high aspect ratio" > > paddle...is this synonymous for a greenland style paddle, a long narrow > paddle, a long narrow paddle canoe style padle...or ? Aspect ratio is merely the ratio of length to width. In this case, we're talking about the paddle blades. A high aspect ratio paddle blade is long and relatively narrow, and a low aspect ratio blade is short and relatively wide. It's not specific to a greenland paddle, canoe paddle, etc., it's just one measure of blade shape. *************************************************************************** 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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