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#11
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Hard wax v/s liquid wax (and turbulators)
On Wednesday, August 29, 2018 at 7:20:29 AM UTC-5, Tango Whisky wrote:
Le mercredi 29 août 2018 13:42:25 UTC+2, Martin Gregorie a écritÂ*: Read up on turbulators. They're not needed on modern airfoils, Except that ALL modern airfoils use turbulators. I am pretty certain that on my ASW-27B the only turbulators on the wings are small 2cm wide sections just in front of the underside NACA vents which pressurize the ailerons and flaps. I can only guess at the aerodynamics of the turbulator's purpose here but this might be an example of this particular modern airfoil NOT needing turbulators (per Schleicher at least). ;-) Remind me - how did we get from talking about waxing onto the subject of turbulators? ;-) |
#12
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Hard wax v/s liquid wax (and turbulators)
On Thu, 30 Aug 2018 06:59:34 -0700, OHM Ω http://aviation.derosaweb.net
wrote: Remind me - how did we get from talking about waxing onto the subject of turbulators? ;-) ....via the Dimpled Golfball highway -- Martin | martin at Gregorie | gregorie dot org |
#13
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Hard wax v/s liquid wax (and turbulators)
Le jeudi 30 août 2018 15:59:36 UTC+2, OHM Ω http://aviation.derosaweb.net a écritÂ*:
On Wednesday, August 29, 2018 at 7:20:29 AM UTC-5, Tango Whisky wrote: Le mercredi 29 août 2018 13:42:25 UTC+2, Martin Gregorie a écritÂ*: Read up on turbulators. They're not needed on modern airfoils, Except that ALL modern airfoils use turbulators. I am pretty certain that on my ASW-27B the only turbulators on the wings are small 2cm wide sections just in front of the underside NACA vents which pressurize the ailerons and flaps. I can only guess at the aerodynamics of the turbulator's purpose here but this might be an example of this particular modern airfoil NOT needing turbulators (per Schleicher at least). ;-) Turbulators are either zig-zag / dimple tapes (all non-Schleicher), or blow holes (Schleicher). Both do the same job. |
#14
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Hard wax v/s liquid wax (and turbulators)
I am pretty certain that on my ASW-27B the only turbulators on the wings ar= e small 2cm wide sections just in front of the underside NACA vents which p= ressurize the ailerons and flaps. I can only guess at the aerodynamics of = the turbulator's purpose here but this might be an example of this particul= ar modern airfoil NOT needing turbulators (per Schleicher at least). ;-) And what is the purpose of pressurizing the ailerons and flaps?? Could it be to actually pressurize the blow hole turbulators (which some manufacturers have substituted Z-tape or dimple tape for because of ease of construction and reduced maintenance issues)???? RO |
#15
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Hard wax v/s liquid wax (and turbulators)
On Thursday, August 30, 2018 at 9:59:36 AM UTC-4, OHM Ω http://aviation.derosaweb.net wrote:
On Wednesday, August 29, 2018 at 7:20:29 AM UTC-5, Tango Whisky wrote: Le mercredi 29 août 2018 13:42:25 UTC+2, Martin Gregorie a écritÂ*: Read up on turbulators. They're not needed on modern airfoils, Except that ALL modern airfoils use turbulators. I am pretty certain that on my ASW-27B the only turbulators on the wings are small 2cm wide sections just in front of the underside NACA vents which pressurize the ailerons and flaps. I can only guess at the aerodynamics of the turbulator's purpose here but this might be an example of this particular modern airfoil NOT needing turbulators (per Schleicher at least). ;-) Remind me - how did we get from talking about waxing onto the subject of turbulators? ;-) Your glider uses blow turbulators, located at the proper point, which happens to be on the control surfaces. To ensure full flow and pressure to the NACA inlets Schleicher puts double thickness zig zag tape in front of the inlets. This trips the flow to turbulent and ensures the effectiveness of the NACA inlets as a supply source. UH |
#16
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Hard wax v/s liquid wax (and turbulators)
On Thursday, August 30, 2018 at 8:37:17 AM UTC-6, Tango Whisky wrote:
Le jeudi 30 août 2018 15:59:36 UTC+2, OHM Ω http://aviation.derosaweb.net a écritÂ*: On Wednesday, August 29, 2018 at 7:20:29 AM UTC-5, Tango Whisky wrote: Le mercredi 29 août 2018 13:42:25 UTC+2, Martin Gregorie a écritÂ*: Read up on turbulators. They're not needed on modern airfoils, Except that ALL modern airfoils use turbulators. I am pretty certain that on my ASW-27B the only turbulators on the wings are small 2cm wide sections just in front of the underside NACA vents which pressurize the ailerons and flaps. I can only guess at the aerodynamics of the turbulator's purpose here but this might be an example of this particular modern airfoil NOT needing turbulators (per Schleicher at least). ;-) Turbulators are either zig-zag / dimple tapes (all non-Schleicher), or blow holes (Schleicher). Both do the same job. Which again comes back to the smoothness of the wing surface as it potentially relates to dimples in a golf ball. With a rough wing surface (from sanding?), would that have the same effect on the surface boundary layer potentially? Would there be a part of the airfoil that would benefit more from such a treatment? And thus, how important to polish the surfaces to a mirror finish? |
#17
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Hard wax v/s liquid wax (and turbulators)
Didn't Dick Johnson run some tests on a Pik-20 that suggested that smooth but not polished was very slightly better than waxed to a mirror finish?
One would think that an Akaflieg would have looked at this in a wind tunnel. My gut feeling is that the mirror finish doesn't really help, but is "expected", much like T-tails; but that if you can feel the roughness with your hand it will hurt the performance "a bit", whatever that is. Anyway, it's more fun to win in a ratty looking glider than to lose in a perfect one ;^) Kirk |
#18
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Hard wax v/s liquid wax (and turbulators)
On Thursday, August 30, 2018 at 2:59:36 PM UTC+1, OHM Ω http://aviation.derosaweb.net wrote:
On Wednesday, August 29, 2018 at 7:20:29 AM UTC-5, Tango Whisky wrote: Le mercredi 29 août 2018 13:42:25 UTC+2, Martin Gregorie a écritÂ*: Read up on turbulators. They're not needed on modern airfoils, Except that ALL modern airfoils use turbulators. I am pretty certain that on my ASW-27B the only turbulators on the wings are small 2cm wide sections just in front of the underside NACA vents which pressurize the ailerons and flaps. I can only guess at the aerodynamics of the turbulator's purpose here but this might be an example of this particular modern airfoil NOT needing turbulators (per Schleicher at least). ;-) Remind me - how did we get from talking about waxing onto the subject of turbulators? ;-) With modern glider aerofoils having such long laminar flow on the lower surface the blowholes on the various ASW-type ailerons/flaps *are* the turbulators on the wing aerofoil. Same as the JS aerofoil with blowhole turbulators at 95% chord which happens to lie on the flaperons. |
#19
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Hard wax v/s liquid wax (and turbulators)
On Thursday, August 30, 2018 at 1:02:35 PM UTC-4, John Foster wrote:
On Thursday, August 30, 2018 at 8:37:17 AM UTC-6, Tango Whisky wrote: Le jeudi 30 août 2018 15:59:36 UTC+2, OHM Ω http://aviation.derosaweb.net a écritÂ*: On Wednesday, August 29, 2018 at 7:20:29 AM UTC-5, Tango Whisky wrote: Le mercredi 29 août 2018 13:42:25 UTC+2, Martin Gregorie a écritÂ*: Read up on turbulators. They're not needed on modern airfoils, Except that ALL modern airfoils use turbulators. I am pretty certain that on my ASW-27B the only turbulators on the wings are small 2cm wide sections just in front of the underside NACA vents which pressurize the ailerons and flaps. I can only guess at the aerodynamics of the turbulator's purpose here but this might be an example of this particular modern airfoil NOT needing turbulators (per Schleicher at least). ;-) Turbulators are either zig-zag / dimple tapes (all non-Schleicher), or blow holes (Schleicher). Both do the same job. Which again comes back to the smoothness of the wing surface as it potentially relates to dimples in a golf ball. With a rough wing surface (from sanding?), would that have the same effect on the surface boundary layer potentially? Would there be a part of the airfoil that would benefit more from such a treatment? And thus, how important to polish the surfaces to a mirror finish? There isn't a meaningful benefit beyond the smoothness of a 400 grit finish, other than easier cleaning and longevity. Waviness and correct shape are more important. Some airfoils like a little roughness. My old PIK-20 was a bit better with 400 surface than polished. When it would drop off in climb, I'd scuff with 400 back about 4 inches and the climb got better. I haven't see any other airfoils that showed that characteristic. FWIW UH |
#20
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Hard wax v/s liquid wax (and turbulators)
On Thursday, August 30, 2018 at 12:26:43 PM UTC-5, kirk.stant wrote:
"It's more fun to win in a ratty looking glider than to lose in a perfect one" Dan Sazhin, I think you need to put that on a tee shirt! |
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