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Better Boundary Layers
On Tue, 8 Jul 2003 17:08:46 -0700, Eric Greenwell
wrote: No, but Dick only tested one glider, and a very early one (early '94 production). Several changes have been made in the wing since then, such as more blowholes, adding winglets, an additional flap position, and using NACA ducts instead of pitot tubes. My experience flying my ASH 26 E (built in early '95, retrofitted with NACA ducts and winglets, and no profiling or sanding of the surfaces) against DG 800s and Ventus 2 CMs is that all three have nearly indistinguishable performance differences. But the 26 is the only one with blow turbulators and it goes no better than the two gliders without. I think you just made my point. Mike |
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"Mike Borgelt" wrote in message But the 26 is the only one with blow turbulators and it goes no better than the two gliders without. I think you just made my point. Mike So how's that prove BHs are ineffective? One could also say the 26e design is somehow otherwise aerodynamically slightly inferior to the other gliders mentioned. And that the BHs make up for this by bringing the 26's performance up to par. Not saying I really buy this, but it makes about as much sense. I suspect blow turbulators provide a slight incremental improvement and other manufactures don't think the gain justifies expense. Either way, it doesn't much matter to me . . . they're on my 26e and they are way cool. To those less fortunate "blowholeless pilots", I say, "tough"! -- bumper "Dare to be different . . . circle in sink." to reply, the last half is right to left --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.495 / Virus Database: 294 - Release Date: 6/30/2003 |
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On Thu, 10 Jul 2003 00:20:05 GMT, "John Morgan"
wrote: "Mike Borgelt" wrote in message But the 26 is the only one with blow turbulators and it goes no better than the two gliders without. I think you just made my point. Mike So how's that prove BHs are ineffective? One could also say the 26e design is somehow otherwise aerodynamically slightly inferior to the other gliders mentioned. And that the BHs make up for this by bringing the 26's performance up to par. Not saying I really buy this, but it makes about as much sense. I suspect blow turbulators provide a slight incremental improvement and other manufactures don't think the gain justifies expense. That is about what I said. Nobody can point to a definitive real world advantage held by any production glider with blow hole turbulators. Hence blow turbulators have not become universal. Mike |
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Yeah but sure they're cool when showing your new glider to your friends...
I prefer old fashioned zigzag tape. Easier to mantain and clean. Good flights Jose M. Alvarez ASW24 "Mike Borgelt" escribió en el mensaje That is about what I said. Nobody can point to a definitive real world advantage held by any production glider with blow hole turbulators. Hence blow turbulators have not become universal. Mike |
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But the 26 is the only one with blow turbulators and it goes no better
than the two gliders without. I think you just made my point. Mike In the case of the 26 and 27 one must not narrow it down to just the blow holes. Aside from the structural features, the gliders have incorporated truly aerodynamic advances. For the gliders to perform as they do everything had to work just right. Consider the fact it has the smallest wing area of the " three" the Diana is even smaller. It has the highest dry wing loading of any 15meter class glider. Still it is able to soar with the lightest in its class, with only the slightest disadvantage. As soon as the wingloading goes up, when conditions allow, this glider is in a class by it self. At the time I thought Waible should have gone about it incrementally, rather then design a radical new glider for production. Look at the fuselage shape only, it required a new wing/fuselage juncture. The others still use the wing straight into the fuselage. The airfoil had to generate more lift due to smaller wing area as well make it thinner to reduce drag. A small gain could be realized with the higher aspect ratio that came with this wing lay out. Waibel was the man that knew/felt laminar flow could be obtained past 90% of chord across a hinge line. He pursued that goal with the help from Loek Boermans. Also the wing fuselage intersection was L. Boermans doing. The blow holes are not an insignificant part in making the glider what it is. If it could just shed 75lb of its empty weight and we would not have this discussion about blow holes. Regards Udo |
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The Idafleig tests show that the '27 polar is in a class of its own, and
significantly better than the Ventus 2. See page 168 of Fundamentals of Sailplane Design by Fred Thomas. "Udo Rumpf" wrote in message ... But the 26 is the only one with blow turbulators and it goes no better than the two gliders without. I think you just made my point. Mike In the case of the 26 and 27 one must not narrow it down to just the blow holes. Aside from the structural features, the gliders have incorporated truly aerodynamic advances. For the gliders to perform as they do everything had to work just right. Consider the fact it has the smallest wing area of the " three" the Diana is even smaller. It has the highest dry wing loading of any 15meter class glider. Still it is able to soar with the lightest in its class, with only the slightest disadvantage. As soon as the wingloading goes up, when conditions allow, this glider is in a class by it self. At the time I thought Waible should have gone about it incrementally, rather then design a radical new glider for production. Look at the fuselage shape only, it required a new wing/fuselage juncture. The others still use the wing straight into the fuselage. The airfoil had to generate more lift due to smaller wing area as well make it thinner to reduce drag. A small gain could be realized with the higher aspect ratio that came with this wing lay out. Waibel was the man that knew/felt laminar flow could be obtained past 90% of chord across a hinge line. He pursued that goal with the help from Loek Boermans. Also the wing fuselage intersection was L. Boermans doing. The blow holes are not an insignificant part in making the glider what it is. If it could just shed 75lb of its empty weight and we would not have this discussion about blow holes. Regards Udo |
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