years ago i built a bunch of pink foam 48" ws .40 combat wings, full span elevons no rudders just twin fins the egine was mounted in the wing prop flush with Leading edge center chord was 20" tips were 8" fully symetrical airfoil and a bit over 2" thick. the spar (1/4" door skin) lined up with the wing tip leading edge and it was the cg. they werent very fast but boy did they handle well and they would inverted flat spin (secret combat tactic ..play dead then attack) at the time they only cost $20 to build the airframe