flywheels

[hinshawracing]

is using two 10in flywheels better than one big 20in flywheel???
10 in dia by 4 in think or 20in by 4in ..
need for inertia mass on dyno?????

 

[kvom]

The moment of inertia of a solid disk is proportional to r^4. Therefore a 20" flywheel will have approximately 8 times the inertia of a 10" wheel (assuming the same thickness).

 

[hinshawracing]

thanks.

 

[mklotz]

The moment of inertia of a solid disk is proportional to r^4. Therefore a 20" flywheel will have approximately 8 times the inertia of a 10" wheel (assuming the same thickness).

Huh? 2^4 = 16 not 8

The moment of a disk is (MR^2)/2. Simply doubling the radius while the mass remains constant increases the moment by a factor of 4.

If you assume that the thickness remains constant then when you double the radius the mass increases by a factor of 4 and R^2 increases by a factor of 4 for a total increase of a factor of 16.

 

[MachineTom]

Without doing the math, a spoked flywheel there is a much higher percentage of its mass in the rim compared to a smaller diameter wheel. MHB older editions like 14 (1952) have all the formula's for max speed, force, burst ect.

 

[steamer]

Hi Hinshawracing,

Might be best if you post a drawing of what your up to....picture's worth a thousand words...and all that.

Dave