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r/R Ia/I (%) 0.000 100.000 0.100 99.990 0.200 99.840 0.300 99.190 0.400 97.440 0.500 93.750 0.600 87.040 0.700 75.990 0.800 59.040 0.900 34.390 1.000 0.000

It certainly shows the significance of the rim mass, though I note that for flywheels like the MEM Corless, r/R is greater than 90%, so the inertia is much less than the whole disk. However, that formula shows how a small difference in r makes a big difference to the inertia.

It seems like the first step is to determine how to calculate the flywheel moment needed by the engine and the error band of that computation.

That was what I expected when I first saw the topic appear.

PS JasonP, can you please send me the dimensions for the thickness and cross section of the rim of the 6.75 inch flywheel you eventually made.