Miles, if you do make such a template, I'd like to know if you can do
it from Europa's actual coordinates. Why didn't they published them
for us Mk 1 types? I made up sanding blocks for the LE, in a J-shape,
using foam and Bondo to mold the LE prior to filling. Since chord
thickness varies, I ended up with 3 of them. Where this may not have
preserved the shape accurately, it's easy to tell one's self that it
may have improved on Mr. Dykins' airfoil by luck.
I didn't think of using a notched trowel, but it may be an excellent
idea. It will sand quicker and produce less overall waste. When you
have a full layer, it sands slow, meaning either lots of work, or just
leaving the excess weight there.
The limiting factor on depth of filler is anywhere you're approaching
exposure of the glass cloth, and the problem of the bump over the
spar. Until the ridges are filled, it will be impossible to feel any
profile. The way mine came out (and presumably aerodynamically best
even if not Dykins' exact profile), is a fairly constant curvature on
the middle 60% of chord. I would have tried a sanding block of
uniform curvature, molding say 18" fwd of spar, and fix the
indentation made by the glass tapes. Then use that to sand the
ridges in the middle 60% spanwise, until above limitations are
reached. This then demands notch-trowling spanwise.
Since you can't sand in between ridges, on the 2nd application of
filler, I think it would be important to wash out all sanding dust,
for best adhesion.
Regards,
Fred F., A063
Miles McCallum wrote:
>
> The method I was considering for filling... is:
>
> - Using the Polyfiber stuff.
> Usual prep, wipe on a coat to fill the weave.
> Use a notched spreader to "overfill" all the areas requiring reprofiling.
> reprofile accurately - I'm considering CNC cut LE templates, back about 4"
> to get that bit accurate (even if the rest is a bit variable)
> Fill the notches, finish sand, etc etc.
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