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Flywheel Energy

E = ½Jω². Energy scales with the square of speed, so a small speed drop releases a lot. Sizing from a duty cycle: J = E/(Cs·ω²), where Cs is the allowed coefficient of speed fluctuation.

Inertia & stored energy

Shape

Mass (kg)

Outer radius (m)

Inner radius (m)

Speed n₁ (rpm)

Speed n₂ (rpm)

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Inertia J

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Energy released n₁→n₂

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Tip speed

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Required inertia from duty

Energy fluctuation (J)

Coefficient Cs

Mean speed (rpm)

Required J

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Check burst margin — tip speed drives hoop stress. A helper, not a substitute for engineering judgment.