Make a carbon fiber spar out of 1/2" CF stock, if you can find a 6' long piece wide enough. It appears that the wing breaks at the first rib, which looked weak to me when I built mine, so I added triangle stock. Another way would be to sandwich aluminum between the spar pieces, maybe 1/4" thick, or two 1/8" thick pieces that go from wing to wing out about to the 4th rib.