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#1
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Humpback whales - a source of new aerodynamics?
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#2
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Another possibility that I recently heard about that might help
increase our L/D: It seems that marine mammals may shed microscopic amounts of their skin as the swim, disrupting the normal boundary layer turbulence. I guess a whale that uses Head & Shoulders Shampoo will not swim as fast as the others? Anyone else hear of this theory? Or think I was being ribbed? Or have any thoughts on how it might be used in sailplane wing designs? Martin |
#3
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I have thought of putting some type of soap on my glider when it may rain,
thinking it would help to level the water drops and maintain the airfoil shape. This may be the thing for the Pik 20 owners and other airfoils that suffer in the rain. Pete "Martin Hellman" wrote in message om... Another possibility that I recently heard about that might help increase our L/D: It seems that marine mammals may shed microscopic amounts of their skin as the swim, disrupting the normal boundary layer turbulence. I guess a whale that uses Head & Shoulders Shampoo will not swim as fast as the others? Anyone else hear of this theory? Or think I was being ribbed? Or have any thoughts on how it might be used in sailplane wing designs? Martin |
#4
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#5
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At 04:18 27 May 2004, Pete Russell wrote:
I have thought of putting some type of soap on my glider when it may rain, thinking it would help to level the water drops and maintain the airfoil shape. This may be the thing for the Pik 20 owners and other airfoils that suffer in the rain. What other gliders are known to have this problem with water or turbulent air? Seems I have heard that one of the ASW series was similarly affected. Pete 'Martin Hellman' wrote in message . com... Another possibility that I recently heard about that might help increase our L/D: It seems that marine mammals may shed microscopic amounts of their skin as the swim, disrupting the normal boundary layer turbulence. I guess a whale that uses Head & Shoulders Shampoo will not swim as fast as the others? Anyone else hear of this theory? Or think I was being ribbed? Or have any thoughts on how it might be used in sailplane wing designs? Martin |
#6
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What other gliders are known to have this problem with water or turbulent air? Seems I have heard that one of the ASW series was similarly affected. Pete Pete, I posted this about a month ago. Sent: Thursday, April 29, 2004 7:14 PM Subject: Pic 20's in the rain Max, Most gliders of that generation use the Wortmann FX 67 airfoil, which has degraded performance when wet. Some examples are : Kestrel, DG-400, Pik-20, Nimbus 2, Lak-12, LS-3, Janus, HP-18, Jantar 2B Apparently some are worse than others, I suppose this is due to the fact that some use this profile on the wing roots only, with a different profile towards the wingtips (these being "better" or more "tolerant"), while some use the FX-67 from root to tip. But it could be something else. Apparently the laminar flow is disturbed very easily on this profile, so not only water, but bugs will degrade their performance as well. Reading Dick Johnson's flight tests, especially some from the 70s, will tell you a little bit more about this. If you go to this link (http://www.ssa.org/Magazines/Johnson.asp) and scroll down, there are 3 reports about the Pik-20, very illuminating. |
#7
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For years, when expecting rain, it has been normal
to wipe a soapy chamois over the leading edges of hang gliders before takeoff. The difference is staggering to those wings more affected by the droplets - a huge improvement. I've had some stuff in my bag for the glider, but haven't tried it, since gliders seem to avoid the rain better. Also the difference in speeds must change things - any aerofoil experts care to comment? Pete Harvey At 04:48 27 May 2004, Nyal Williams wrote: At 04:18 27 May 2004, Pete Russell wrote: I have thought of putting some type of soap on my glider when it may rain, thinking it would help to level the water drops and maintain the airfoil shape. This may be the thing for the Pik 20 owners and other airfoils that suffer in the rain. What other gliders are known to have this problem with water or turbulent air? Seems I have heard that one of the ASW series was similarly affected. Pete 'Martin Hellman' wrote in message .com... Another possibility that I recently heard about that might help increase our L/D: It seems that marine mammals may shed microscopic amounts of their skin as the swim, disrupting the normal boundary layer turbulence. I guess a whale that uses Head & Shoulders Shampoo will not swim as fast as the others? Anyone else hear of this theory? Or think I was being ribbed? Or have any thoughts on how it might be used in sailplane wing designs? Martin |
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