A laboratory model simulating, insofar as practical, a single axis of a space vehicle with a reaction wheel control system was constructed from off-the-shelf components. The operation of this typical system is described as follows deviation of the platform vehicle from a reference attitude is sensed and the resulting error signal is used to accelerate the wheel relative to the platform. The resultant reaction torque on the platform tends to reduce the deviation or error to zero. In the presence of a constant disturbance torque the steadystate behavior of the system results in a constant acceleration of the wheel, i.e., the reaction torque on the platform is equal and opposite to the disturbance torque. The function of the auxiliary gas system is to ensure that the wheel speed is maintained below a pre-set limit. When the wheel speed reaches this pre-set value the gas system is activiated, generating sufficient impulse to reduce the wheel speed to zero. The system then returns to the reaction wheel mode of control. Several novel techniques were used to develop the circuitry to drive the motors. System efficiencies in excess of 80 were achieved thus far for both DC permanent magnet and AC servo-type motors.