Multi-Shaft Reaction Wheel Design For A 2U Cubesat

Abstract

In this paper, a reaction wheel design is presented and proposed for use in Dalhousie University's Low Earth Orbit Reconnaissance Imagery Satellite (LORIS) 2U CubeSat. After estimating a cumulative maximum disturbance torque of 7.16 × 10 -7 Nm in low Earth orbit, a flywheel design was developed with a momentum storage of 1.01 × 10 -2 Nms. The authors propose to machine the flywheel in a skate-wheel shape to provide a large inertia-to-mass ratio compared to solidcylindrical designs. A novel three-shaft system is employed wherein a Brushless DC motor shaft is rigidly connected to a spline-toothed inner shaft which transmits power to an outer shaft rigidly fixed to the flywheel. The inner shaft provides torsional flexibility to the system and ultimately reduces the transfer of vibration due to shaft misalignments. Splines and back-to-back angular contact bearings accommodate axial and radial misalignments between the inner and outer shaft experienced during mounting and operation. Finite element analysis was employed to validate the design across worst-case loading scenarios including rocket launch and misaligned inner and outer shafts.