ESA GNC Conference Papers Repository
Reaction Wheels at Bradford Engineering
In August 2006, Bradford Engineering (BE) acquired the Reaction Wheel Technology originating from Astrium Ltd. (Mechanisms Product Group, Stevenage); this technology has a long and excellent track record. The series of wheels offers superior performance in terms of momentum storage, torque and wheel speed measurement and has excellent zero-crossing and micro vibration characteristics. Under ESA GSTP (General Support Technology Program) funding Bradford Engineering has modernized the Reaction Wheel technology and achieved the qualified supplier status. The aim of the qualification is to qualify a new supply chain and demonstrate successful transfer of profound knowledge and work instructions in the Bradford QMS system. Due to state-of-the-art machinery in the new supply chain, the tolerances of the bearing house assembly parts have been further reduced, leading to higher yield and increased repeatability at the high end performance of the wheels. A two step design upgrade has been initiated. The first step consists of an upgrade of the telemetry capability and improvement of EMC characteristics of the Wheel Drive Electronics. The second step comprises of improved control capability of the wheel speed in order to better serve the increased needs on pointing and stability requirements at satellite level. The former design upgrade has been concluded and was successfully qualified with the wheel. The latter development is ongoing and qualification is planned for Q1, 2012. The performance results of the ongoing qualification tests are presented in this paper. The results are compared to acceptance test results and in-orbit performance data of heritage wheels like Integral, XMM and Rosetta. An additional section will address the status of the lifetime test of the reaction wheels. Initiated by Astrium Ltd.; several wheels have been exercised since 1996 accumulating to over 750.000 zero crossings and 15 years of lifetime on individual wheels respectively.