Development of Reaction Wheels for Cubesats Using a Solid Lubricant Bearing

Abstract

Lubrication of bearings is the most significant element for high-speed rotation of a flywheel in a vacuum environment. This paper proposes a new reaction wheel for cubesats using a solid lubricant bearing. Generally, metal ball bearings and liquid lubricant are used for reaction wheels because liquid lubricant enables stable rotation even in a high-speed range. In contrast, liquid lubricant has a defect that lubrication becomes insufficient when its rotation stops. To protect bearings, it is desirable that a flywheel keeps rotating above a certain speed like momentum wheels. However, this is difficult for cubesats because there is insufficient power supply. To solve this problem, new reaction wheels were developed using polyether ether ketone ball bearings with polytetrafluoroethylene solid lubricant. It can maintain the lubrication effect even if a non-rotational state continues for a long period. Results of this evaluation found that the developed reaction wheel had a maximum torque of 0.189 mNm and a maximum angular momentum of 0.657 mNms. The performance is equivalent when compared to that of conventional-type reaction wheels.