Laminar flow over canopy seam?

J. Nieuwenhuize wrote, On 7/7/2014 12:13 PM:
I asked around a bit in Delft. Seems no documented in-flight tests
have been done, at least I couldn't get hold of them. Surprising
given how simple that'd really be, though a respirator might be
advisable...

Problem of course is that in wind tunnels we don't have seems, nor
are levels of ambient turbulence anywhere as low as in the
atmosphere.

I guess Britton is referring to wind tunnels tests like these
performed in Delft?
http://www.dropbox.com/s/354b4wpodglrw7j/Untitled.jpg

There it's just the effect of the wing/fuselage intersection that
pushes the transition point forward.

What I'm wondering about is whether flow over the canopy looks
anything like the above test, or we basically have a mostly turbulent
canopy, with turbulent wedges originating from all over the canopy
seam.

Because if that's the case, a fully flush canopy (that by definition
would have to slide fwd for ingress) would cause a major drag
reduction. Something like the MOBA:
http://www.dropbox.com/s/vozyc6qby8x...bafullview.jpg

Based on a conversation with Gerhard Waibel 10-15 years ago, the modern
glider canopy is almost entirely laminar. The yaw string will cause a
wedge of turbulent flow behind it; consequently, he recommended
attaching the yaw string as far aft as possible.

I've observed evidence of his statement when in flying cool, humid
conditions. A wedge of condensation will form inside the canopy, behind
the yaw sting, but nowhere else (except possibly some of the rearmost
portions of the canopy). I attribute this to the turbulent air cooling
the canopy under it more than the laminar air elsewhere.

It's my understanding a well-done canopy seam at the front does not trip
the laminar flow into turbulent flow, because the expanding
cross-section of the fuselage in that area produces pressure
distributions that promote laminar flow.

--
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 - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl