Here is a conventional airframe balsa and ply with some carbon fiber. Less than 10 lbs. capable of lifting 45 lbs in less than 400 ft. High lift very low speed. 14 ft span 14 inch cord using a Selig 1223 airfoil. Take off roll empty about 4 ft power .65 Flys like a big trainer. This was the maiden flight the landing gives an idea of the slow flight landings.

[youtube]http://www.youtube.com/watch?v=g8xC-pE6RoA[/youtube]

Smaller examples limit 1000 square inches and an OS .61

[youtube]http://www.youtube.com/watch?v=vBgWUceKmR0&feature=relmfu[/youtube]