RE: Foam wing Lay Up
Dave,
The glider guys use unidirectional carbon fiber cloth (CF uni-cloth, for short), which is more dent-resistant but also brittle. About 10 years ago I experimented with this on some F3D and Formula 1 wings. My crowning achievement was an F3D Swee'Pea wing that weighed 17 oz. (not too bad for 450 square inches) and was stiff as a surfboard. Unfortunately, the sparless construction didn't hold up very well under vibration, the top skin separated from the foam & it collapsed with a bang on its third test flight. Later versions had a full-depth spar and a thicker top skin, but it was next to impossible to keep the spar from forming a "bump" right at the high point of the airfoil. By the time I'd solved all those problems, it was heavier and much more expensive than a balsa-sheeted wing.
Ed probably remembers my black-and-silver Q40 Stinger that I flew at the Black Hills, SD contest in 2001. That airplane had blue foam cores, full-depth spar, 2-oz. glass on the bottom, 1/16" balsa and 2-oz. glass on top. It was built in a smooth fiberglass cradle that I waxed and laid up the bottom skin on -- sort of halfway between the CNC aluminum mold method and the conventional method. Looked good, came out light, went fast, but every time I picked up the airplane I put fingertip dents in the bottom skin. Now I'm back to balsa skins. Live and learn!
DHG