Originally Posted by Neil Stainton
A spar needs a shear web to work. If you change the spar caps to carbon you will have to also increase the strength of the web in proportion. Probably just increasing the vertical grain balsa web thickness to the full width of the spar cap will be okay.
That is what I'm doing for a spar mod on my next woodie project. In fact it is going to much like the Maxa spar. It will comprise of 4 pieces of balsa cut on a 45 degree bias laminated together with a .014 carbon core. spar caps will be dimensional carbon wrapping with Kevlar. I figure it should be full-peddle winch safe.