The USAFCAL variable stability T-33 airplane is a jet trainer which has been extensively modified for use as a research vehicle. A response-feedback system allows the normal T-33 derivatives to be augmented so that handling qualities of existing airplanes, future airplanes, or hypothetical configurations may be simulated in flight or in a fixed-base ground simulator. The report attempts to provide an updated functional description of the variable stability T-33. The information is presented for setting up a simulation program and for performing calibration procedures. A brief description of the equipment and airplane systems is also included.