Well rounded wingtips on a constant chord wing were found in wind tunnel tests to reduce minimum drag by about 5%, and induced drag by about half as much as the best form of taper, which was found to be about 70%, after factoring out the increase in aspect ratio resulting from removing area from the tip. The tip form was composed of two semi-ellipses, with about twice as much area removed from the trailing edge as from the leading edge, with the trailing edge tip curve extending inward on the span by about one chord.

The negatively raked wingtips of some WW1 airplanes were found to be particularly bad - a simple rectangular tip performed better.