The most successful NASA experimental results were obtained on a quite low 6:1 aspect ratio wing (Grumman Yankee AA-1), with a DLE placed at 57% of the semi-span. As the vortices (inboard cuff and wing tip) are efficient on a limited span length (about 1.5 times the local chord), a DLE alone is unable to preserve enough outboard lift to keep the roll control in case of high aspect ratio wing.[16] Wings of more than 8 or 9 aspect ratio features other devices to complete the cuff effect,[17] for example stall strips (as used on the Cirrus SR22 and Cessna 400), "Rao slots" (as used on the Questair Venture), vortex generators or segmented droop (as used on a NASA modified Cessna 210). In the case of the high aspect ratio Cessna 210 wing (AR =11:1), roll damping at stall was not as efficient.[18]