In article ,
says...
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.

I was answering your comment about the "terrible" ASH 26 polar. For
the blow turbulators, I previously tried to make the point that they
may indeed be the best choice for the airfoil that Schleicher chose.
The fact that it didn't give Schleicher a "definitive" advantage
doesn't mean this isn't true, as performance is affected by other
factors, such as the wing design (area, aspect ratio, winglets, etc),
fuselage and tail design, and so on.

Regardless of whether the ASH 26 would work just as well with zig-zag,
it is obvious to the pilot the blow turbulators are doing something!
Taping over just one NACA duct elicits an loud and eery chorus that
the Louek Boermanns, the airfoil designer, says is a vortex forming
behind the trailing edge of the wing. I can also hear the vortex in
wave conditions when the flaps are not set properly.
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Eric Greenwell
Richland, WA (USA)