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. Features- • High torque level over full speed range • Fixed torque rise time allowing precise and repeatable control over full speed/torque range • Analogue or Digital interface • Accurate wheel speed signal • Proven zero crossings and low RPM performance with excellent micro-vibration performance • Lifetest and in-orbit heritage Technical Specifications- • Momentum Storage (Nms): 40 • Maximum Operational Speed (RPM): 4000 • Number of pulses per revolution: 240 • Maximum Gross Torque (Nm): 0.248 • Typical Torque Loss at max. speed (Nm): 0.037 • Static/dynamic imbalance (g.cm, g.cm2 ): 0.5/5.0 • RWA Dimensions (mm): Ø365×125 • RWA Mass (kg): 6.70 • 2-channel WDE Dimensions (mm): 258×181×143 • 2-channel WDE Mass (kg): 4.67 • Torque rise/fall time (ms): 80 • Peak Power Consumption at max. torque and speed (W): 168 • Steady State Consumption at max. constant speed (W): 29 • Quiescent Power Consumption (W): 7.6 • Power bus interface: 28Vdc or 50Vdc • Data interface: MIL-STD-1553B or analogue • TM/TC frequency: up to 10 Hz • Qualification Random Vibration — RWA: [IP: 10 gRMS, OoP: 15 gRMS (including notch to protect bearings)] • Qualification Random Vibration — WDE: [IP: 11.2 gRMS, OoP: 17.4 gRMS] • Qualification Operational temperature — RWA: -15°C to +60°C • Qualification Operational temperature — WDE: -30°C to +60°C • Shock environment — RWA: 400g – 2000 g depending on balancing requirements • Shock environment — WDE: 2000 g Applications- • Satellite Rotational Control