Abstract Composite flywheels for energy storage have been proposed and investigated for the past several decades. Successful applications are, however, limited due to the inability to predict the performance – especially the long-term durability. In this investigation, a comprehensive study was proposed with the intent to implement composites in high performance flywheels. The potential failure mechanism of flywheels constructed with fiber composites was evaluated. Analytical codes for predicting elastic and viscoelastic (long-term) behavior was developed for flywheel design. Material characterization and test matrices were proposed to design flywheels with maximum performance. Component level test methods and devices were developed to validate flywheel performance. Finally, a methodology incorporating these studies is presented for the design and manufacture of composite flywheels.