What does the damage (as I understand it) is not the rotational forces but the bending force the propeller imposes along the axis of the crank. These bending loads are practically non existent in an automotive application and I'm not sure a flywheel of any weight would make much difference.
The problem arises from fact that the centre of lift of each propeller blade is quite a way off the axis of the crank. Averaged over time the 'lift' (perhaps more commonly called thrust) generated by each blade is close enough to the same, but at any instant, the lift generated by each blade is not the same as the other blades (due the angle of the propeller to the airstream - which is not always a right angle, imperfections, slight differences between blades, etc.), resulting in a force that imposes a bending load on the crank. Based on the experiences of those who've been there, it seems the big fifth bearing now being implemented by Corvair builders moderates but doesn't completely eliminate the effect of the crank bending forces imposed by the prop. Having dismissed the flywheel at the start of my email, it's just occurred to me that a flywheel at the prop end might help reduce the bending force by way of the gyroscopic effect of the flywheel acting against the bending force of the prop. Sadly I don't have the theoretical background to work out whether a flywheel of tolerable weight and dimensions could make a useful contribution. Any takers? Cheers, Tony King Queensland Australia > On a theoretical note: Isn't the flywheel meant to store the energy > imparted to the crank between the power pulses? And if that is the case, > doesn't a lighter flywheel tend to cause the torsion differential > between the pulses on the crank to increase versus a heavier flywheel > which will tend to store the energy longer. This is comparable to what a > filter circuit does in electronics. If I reduce the capacity of a > filter, then the ripple voltage will increase, especially under heavy > loads. Perhaps a heavier flywheel should be considered, especially in > an engine which is being increased in its power output. I'd be > interested in hearing the science on this. > >
