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, maximising the available heritage database.

Key Advantages

  • 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
  • Most braking energy is dissipated within the WDE. No energy is injected back into the S/C power bus.
  • Lifetest and in-orbit heritage (SOHO, RadarSat, Seastar, Olympus, Integral, XMM, Rosetta, Aeolus, BepiColombo)