Eric Greenwell wrote:

Doug Hoffman wrote:
tango4 wrote:


yes it's 'normal' and yes it will affect performance

it needs fairing, filling and refinishing.

Ian


Yes. According to Richard Johnson a laminar flow airfoil not only needs to
be accurate in shape , but it needs to have no "waves" larger than +/- .002"
in 2", in order to extract best performance. If you can see and feel the
bump of the spar you are violating both of these criteria. Fairing and
refinishing a wing, and making sure the airfoil is correct, is not a small
task, but doable. I am (finally) finishing up my RS-15 wings. I know the
shapw is accurate and I know the +/- .002" waviness limit is not exceeded
(this is best checked with a dial indicator).

I thought Johnson's criteria was +/- .004".

Eric,

After reviewing the articles I could find with more care, and with Udo's
input, I think .008" peak-to-peak (or +/- .004") is too large a wave for
laminar flow.

Regards,

-Doug