The upswept wingtip option on the Top Flite Contender is to eliminate adverse roll coupling when you apply rudder. With the standard tips, you'll get left roll when you apply right rudder, and vice-versa. The upswept tips give you proverse coupling: right rudder results in a right roll, and vice-versa. The model has not had a problem with tip stalls, regardless of the type of wingtips installed.