The NASA F-15 is shown fitted with the 10 degree cone experimental device. The cone - attached to the nose of the F-15 - was flown at transonic and supersonic speeds in order to verify data obtained at 23 transonic and supersonic wind tunnels. The four initial flights occurred in October 1977 by NASA research pilots Einar K. Enevoldson and William H. Dana. After the aircraft was grounded for installation of the data acquisition system, the two pilots resumed flights on April 28, 1978. A total of 46 flights with the 10 degree cone were made before this initial series ended with a final flight on November 21, 1978. Grounded for a year to undertake maintenance and the installation of a new rotating cone experiment, the F-15 flew again between March 14, 1980 and June 16, 1980. A total of 13 additional research flights were made, piloted by Enevoldson, Dana, and Michael Swann. Once this second series of tests ended, the 10 degree cone program drew down, and the F-15A was grounded for installation of Digital Electronic Engine Controls.