I experimented with the Klein-Fogelman airfloil on models in the late 80s and found them to be as the originators stated. They were very difficult to stall. I saw no other positive characteristics in comparing them to the Kadet Sr. but, I like to experiment and the experiment was fun.

Tattoos knife edge Le airfoil does fly OK. It will haul a plane thru the air when properly powered, and is cheap and easy to build. It's ugly, but then so are some of us pilots, so no criticism there. I've built many of them, and still build them. (built two wings today.

BUT, the LE is in need of improvement ON SOME airplanes. Sharp LE airfoils are fine on very fast planes, but most of us don't fly very fast planes. Many of us, who still like to experiment, have found the coroplast wings are significantly improved with some rounding of the leading edge. Even a quarter inch radius makes a big difference in the slow speed flight characteristics.

One of the prominenet Spad guys simply puts a 3/8" flat leading edge in his. We have found this to be an improvement over the sharp LE. Why a flat leading edge works is beyond me. One of our guys has built several trainers with the Spad wing only with a well rounded leading edge of about 3/4" radius. It is the best flying Spad wing I have flown, and compares favorably to the Kadet Senior, the plane by which all other trainers are judged.

Until I see a "rolled vortex", or a "bound vortex" on a 45 MPH trainer, I would be skeptical. Yes, I've seen them on supersonic jets, but on model trainers :stupid: :stupid:

I've never seen a perfect airfoil for all airplane configurations. The sharp LE does work Ok on sticks, combat craft, and wild aerobatic, poke holes in the sky ships. Pitch instability in these planes is usually not noticed as we are banging the sticks around most of the time anyway.

But in a slow stable ship used primarily for training and lazy day flying, the sharp LE does want to hunt in pitch unless the ailerons are reflexed up slightly. And reflexing the ailerons does increase the landing speeds and stall speeds. What's the old saying, "nothing is free".

So, until someone finds a better alternative, I will continue to build coroplast wings, but add a little rounding or bluntness to improve the flight characterisitics. No criticism here, just a little difference of opinion.

Cajun