A two cylinder engine with the cranks at right angles developes 75 KW at mean speed 400 rev/min. The coefficient of speed fluctuation should be more than 0.003. The mean diameter of flywheel is 1.2 m. The maximum variation of energy for each revolution is found to be 20% of the mean energy. As found from dynamic analysis of the actual forces in the engine.if the arms and hub contribute 5% of the flywheel effect (K=0.95),what is the necessary dimensions of a square rim section of cast iron which has density of 7000 kg/meter cube?