FLIGHT EXPERIENCE WITH THE OGEE WING AT LOW SPEED,

A basic delta-wing aircraft was modified to an Ogee plan form and tested in flight following full-scale wind-tunnel tests. The modified wing had a sharp leading edge compared to the original large-radius, slatted leading edge. The modification produced strong leading-edge vortices which were easily observed and photographed as condensation trails. The stability of the vortices was examined in flight to 25 degrees angle of attack and 8 degrees sideslip and no detachment of the vortices or other discontinuous characteristics were indicated. A significant improvement in lateral-directional stability over that of the basic airplane was obtained at high angles of attack, which allowed a reduction in the minimum instrument approach speed. The improved lateral-directional characteristics made it possible to extend to lower speeds the study of other piloting factors which might determine the minimum approach speed. The effects of a range of static margins from -0.02 to 0.02 were examined. Also, the effect of a change in the slope of the power-required curve, which was obtained by making landing approaches over a range of airspeeds, was investigated. Poor static longitudinal stability and reduced flight-path-angle control became the limiting factors. Author