"A flight investigation was conducted with a fighter-type airplane to determine the loss in rolling effectiveness due to wing twist, and the results are compared with the loss in rolling effectiveness calculated by use of a simplified method. The computed rolling velocities showed good agreement with experimentally determined rolling velocities throughout the Mach number range covered by the flights. Extrapolation of the flight data indicated a Mach number for reversal which agreed well with that obtained from calculations" (p. 1)