Well, I wasn't worried about the wing flexing... untill my ailerons wern't responding. After the wing flexed so much, the ailerons would just stop working. That's when I added the extra pieces on the wing. The tail section is braced because I felt the elevator halves were way to weak. I can see doing waterfalls where the elevator halves wouldn't give the same deflection. That and the rudder would flex horribly, even when I was just carrying the plane around. It would probably fly with out it, but this plane is unpredicably enough... I got a new motor and gear box for it tonight, so I'll try that with the lithium polymers.