There appears to be a misconception, that turbulent flow
requires less attention to details regarding surface discontinuity.
In fact some airfoils that maximize laminar must have a minimum
of discontinuity to prevent separation of turbulent flow.
In case of the LS 6 or 8 airfoil the turbulent flow is relative thin
as the laminar flow is not driven to the max and a relative thin
and energetic turbulent flow is maintained, hence the close tolerance of
gap and shape in the LS8 aileron transition can be done without
Mylar tape. It is always a good idea to provide an effective fairing
that assists the flow around deflect surfaces as well as pay attention
to surface details beyond laminar flow transitions.
Udo

What you and Herbert appear to be saying is that thee mylar is only a
fairing, rather than a seal. Since the mylar is in turbulent airflow the
need for a fairing at that point seems limited. At the moment, the seal
is
provided by flexible adhesive tape over the join (upper surface only).
Would I be better off (financially, yes!) to forget about mylar and stick
(not to pun) with the adhesive tape, perhaps on both upper and lower
surfaces?

Simon


"Eric Greenwell" wrote in message
...
Simon Waddell wrote:
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.

I think you are right. In any case, the effect of even perfectly done
fairings is small (you won't notice it, and would have great difficulty
measuring it with flight tests), especially on an older airfoil, so the
effort and cost of recessing the mylar isn't worth it. Be sure there is
an actual _seal_ (flexible tape stuck to the wing and the control
surface) installed, in addition to the mylar fairings, so air can't leak
through the gap.

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Eric Greenwell
Washington State
USA