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).

Regards,

-Doug



"Chris Davison" wrote in message
...
On the top surface of the wings of a 17m Kestrel I
am looking at, the spar is clearly visible and you
can feel it (it stands out slightly proud) below the
surface of the wing itself. This is uniform down the
whole spar and on both wings.

Is this 'normal'? Will it affect performance??

Thanks
Chris