>what do you mean with a "slightly curved spline" designated
>as "slightly flexible" to use for sanding the wing surfaces?
>That is just the work I a still have to to with my Europa no
>91.
Hello Erich,
The object is to achieve a smooth curve with gradual change of curvature
that won't trip the boundary layer, the surface already has the overall
shape required, all we have to do is remove the bumps and hollows. The
correct flexibility allows the spline to take up the general curve but be
firm enough to knock off the high spots. A bit of trial and error with
strips of scrap wood or plastic will soon give you a feel for the idea. I
don't believe a rigid straight spline can achieve this.
I used a strip of hard nylon, 1 meter long, 15mm thick and about 60mm wide.
10mm plywood cut along its most flexible direction would work. I stuck
abrasive paper ( bought by the roll) to it with 3M spray can adhesive.The
most critical part of the airfoil is, of course the leading edge. I made up
a series of templates of the first 20% of the section, (10 or 12 of them) ,
using Turbocad to draw them out, then did the leading edge very carefully
to match the profiles. This was on Charlie Laverty's Europa which has not
yet flown.
regards,
Graham
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