Hello again, I am currently designing a flywheel for a 745 KW engine inertia dyno. Basically my design requirements are so: Max RPM: 530 RPM (=55.5 rad/s) Flywheel Diameter: 1.7 meters Time needed to accelerate: 60 second (to max rpm) I need help determining the mass of the flywheel. My calculations and way: Power=745 KW ΔE=P*t=745*60=44700 KJ Inertia for a solid disc (flywheel) = 0.5*m*r^2 Energy in flywheel = 0.5* (0.5*m*r^2)*ω^2 Isolate the mass: m= (4*Energy) / (r^2* ω^2)= (4*44700) / (0.85^2*55.5^2) = 80 tons. 80 tons seems way off, I've gone over my calcs a few times and haven't found my problem. I appreciate any assistance!