What are typical stresses on the struts as compared to sprags?
High performance MDs are designed for 130,000 psi stress at a rated torque. This provides a safety factor of 2 relative to yield strength and a 1.3 safety factor for fatigue. Prototypes have been tested to well over 1 million load cycles at torques which produce 130,000 to 150,000 psi. Sprags are designed to operate at over 250,000 psi contact stress at rated torque. MDs convert 96% of stress to torque, 25% to axial force. Sprags convert 10% of stress to torque, 99% to radial force.
