I too had wondered about this question; my PIK
had ( until I fixed it) a 1/2 mm step at the frame,.
Are there degrees of turbulent as one goes downstream,
or just a thickening BL?
Have to do something about the yaw string; how about tiny ports each side
of the nose feeding a vario differentially
and meter on the cowl Audio optional.
John F

At 14:12 05 July 2014, wrote:
Talk with Boermanns as he and his pals are the gurus. What you're most
like=
ly to get is the hope for re-laminatization after a trip to turbulent.
Roug=
h equation is Re_x 100 for even the hope to get this action in a
proverse=
gradient. X is a step or gap or roughness element or even waviness
perhaps=
..=20

Some nice color flowvis you've probably seen out of the Akafliegs as
well,
=
but even there with no seams and proverse gradient, the flow trips to
turbu=
lent about 30-40% of the canopy highlight and moves aft from there as you
g=
et to the seams. Will also be function of the pressure field around the
win=
g root since that is now a boundary condition for the canopy.=20

Yaw string definitely trips to turbulent, but we need those.=20

Under pressure or suction at the seam due to an extractor? If you could
get=
suction on the whole canopy surface then yes, but if it's only at the
cano=
py gap then no because youre still bounded and hoping for
re-laminarization=
, or at best the calibrated amount of suction at the seam, the flow would
s=
till see a perfect wall and thus you're back into the proverse gradient
que=
stion of the canopy/fuse as a whole.=20

Then you'll get the argument for total drag vs speed and how much comes
fro=
m what part of the glider. Wing, fuse, tail. Canopy drag is combined in
tot=
al fuse drag of course.=20


Good question to ask and will make people think.=20
Britton