FM Telemetry for Multiple Force Measurements on Free-Flying Models

The extension of the FM telemetry technique to provide simultaneous measurements of four forces acting on a free-flight aerodynamic model is reported. Developments and procedures required to achieve the accuracy, linearity, and stability necessary for obtaining dynamic stability coefficients are described. System accuracy is believed to be better than 3 percent. Free-flight data, presented in the form of aerodynamic stability derivatives, are in good agreement with measurements taken by conventional methods under the same aerodynamic conditions.