definately the upswept wingtips,
search for contender and read through the posts

I paste: Those Horner-style upswept tips were designed to eliminate roll/yaw coupling present with the straight/conventional tips. IOW, when you make a rudder input, the opposite wing drops.

found here: http://www.rcuniverse.com/forum/m_85.../tm.htm#857339


i've had so much fun today, aligning the ribs with the spar and gluing together, moved on to the TE installation
and found out that the TE blocks are violently warped and there is no way i can glue them to the ribs like that.

checked the LE blocks, same here, warped blocks, unable to proceed.
guess i have to get the wing off the board, call for replacement or find similar and move on to the fuse.
that sucks.
also almost every rib is broken somewhere, had to go over with ca.
[&o]