"Simon Waddell" simonFUNNYATSYMBOLleswaddells.ch wrote in message ...
I tried asking this questionon on a different thread; it may have been too
off topic, but I didn't get much of a response:

I'm putting mylar control surface seals on the wings of a Mini Nimbus this
winter. At the moment I'm planning on fixing them to the finished wing
surface. The alternative is to rebate (recess) them into the wing. This
creates a smoother surface but costs more money and is harder to undo.

Anyone know of any research (or anecdotes) on the impact on wing performance
of leaving such seals proud of the surface? My assumption is the airflow
over the wing is pretty much turbulent at the wing/aileron join anyway, so
the impact should be minimal.

If the recommendation is to rebate, is it equally critical for the both the
upper and lower surfaces?

I replaced the top surface fabric tape aileron seals with mylar on my
ASW-19b. I didn't use an internal seal on the assumption that the
lower seal would stop any air migration to the top. I only had time
to do one wing before a club contest flight. I noticed a significant
roll towards the unmodified wing. The roll went away when I installed
the mylar seals on the other wing. No rebate, just faired the leading
edge of the mylar with tape.

A lot of advice has ben posted before on the perils of detatching
mylar seals. Make sure you stick them well and inspect before flight.
Also lock the control surfaces neutral when the glider is not in use.
A deflected control surface may cause the seal to take a set and may
also contribute to seal detachment.

Andy (GY)