Been-there-done-that and guess what? Only the first 4 inches are
important. I make up templates before starting, every 24 inches and
then keep everything aft of that dead smooth both cord-wise and span-
wise. Quick and dirty templates can be made from cardboard that is cut
close then crammed over a strip of bondo which is gooped over aluminum
foil every 24" with wing leading edge vertical.
Both Dick Johnson and Allen Bickle made up full scale templates,
worked forever and the bird didn't perform any better than advertised,
except it was a lot heavier because of all that bondo!. Bickle's bird
had a trailing edge that was a good 5mm thick, because that's what the
templates dictated.
Save your time and bondo, concentrate on the first 4".
JJ
When I say bondo, I'm talking about Evercoat Rage Gold, good stuff,
works easy and sticks like mad!


wrote:
On Oct 21, 11:26�pm, "Bill Daniels" bildan@comcast-dot-net wrote:
You know, I've been flying FX 67-150 and -170 airfoils for years. �I've
smashed thousands of bugs, flown through many rain showers and even
collected substantial ice on occasion yet I've not seen any unusual
performance degradation when analyzing flights with SeeYou nor did I feel
any in flight. �

That's astounding...

I owned an HP-18 for years that made an honest 40:1 clean... and about
7:1 in light rain. I'd feel the ship get draggy with the first tiny
spots on the canopy. In a light rain shower the entire ship hummed
audibly and one had to push the stick forward to maintain 55 kts. The
stall speed went up rather a lot too, but I don't recall any
specifics.

More recently, I watched a Glasflugel (or HPH or whatever they are)
304 -- which has a very similar looking airfoil the root if not
precisely the same airfoil -- get "washed" off a ridge in rain showers
that had little effect on my ASW-20. He might as well have flown into
a net.

I wonder if you have a different leading edge section on your ship, by
happenstance or design. It would be very interesting to discover what
the difference is.

-T8