Reply to Phillip Alexander
I don't think a laser would be much help. The important lines on an aeroplane
are all curved. Absolute straightness is only important to the extent that it
looks right. With the exception of hinge lines, of course. There it would be
useful.
The most difficult part in finishing is achieving minimum waviness chordwise. A
figure of less than .003" per two inches is about right. Checked with a feeler
gauge and a steel rule pressed down with finger and thumb 2" apart. Slow
business.
I suggest three rules of thumb:
1 USe a long evenly flexible springy sanding board, 1/4 " ply or similar.
2 Don't press on any harder than necessary to bend the sander to the shape of
the wing. Too hard distorts the skin.
3 Never ever use a rigid flat board, you will just put flats on the curve.
A powerful linear flood light held low down might show up waviness or bumps. Low
evening sun certainly makes things easier.
Graham
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