An in-flight view of the 10 degree cone on the F-15A. The cone - a standard reference device that measured the quality of airflow in 23 wind tunnels - was then mounted on the F-15A and flown at transonic and supersonic speeds. The data from the wind tunnels was then compared with that gathered in actual flight. The experiment provided an assessment of the tunnels' ability to accurately simulate real air flow conditions on models. The information from the 10 degree cone also provided a means to interpret data from each tunnel, helping future researchers to choose the individual wind tunnel best suited for a specific test.