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