The Bradford Reaction Wheel Unit (RWU) channel consists of a Reaction Wheel Assembly (RWA) and one Wheel Drive Electronics Box (WDE). The RWA is a rotating inertial mass, driven by a brushless DC electric motor. When power is applied to the motor, the wheel accelerates, causing the satellite body to which the motor housing is attached to rotate in the opposite direction due to the induced counter torque. A minimum of three sets of RWA are needed per satellite to allow rotational control around the 3 axes. One extra RWA is generally present for redundancy purposes.
Bradford offers a range of RWA to the market, each specifically sized for a particular angular momentum control range. All wheels are based on the same proven design, maximizing the available heritage database.