krasw wrote on 10/26/2016 12:33 AM:
On Wednesday, 26 October 2016 03:26:21 UTC+3, Eric Greenwell wrote:
My guess is the boundary layer is too thick on the control surfaces for
zig zag tape to work, unless it was stacked two or three high.


If the function of blowholes is to trip laminar flow into turbulent, how can laminar flow be "thick"?

I'm not sure what you are asking, but in general, laminar flow has a
thicker boundary layer than turbulent flow, and when it grows too thick,
it separates from the airfoil into a "laminar separation bubble" that is
high drag. The cure is to trip the laminar flow into turbulent flow,
which "sticks" better to the airflow.

Schleicher uses two layers of zig-zag tape just in front of the NACA
inlets that pressurize the control surface blowholes. A single layer is
not thick enough to trip the laminar flow that far back on the airfoil.
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "A Guide to Self-Launching Sailplane Operation"

https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf