Just wondering if someone here can explain the MOI figures sometimes stated with Flywheels.
I'm not sure what is a good figure to be expecting from the lightweight flywheels that are on the market today.
Anyone have any links to articles? or just know off the top of your head?
Many thanks,
Ant
Flywheel Moment of Inertia?
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No idea of actual figures because I've never had to measure it but here's the arithmetic:
Kinetic energy = sum of kinetic energy of individual mass elements that comprise the flywheel
= 1/2 x I x w^
where:
I = moment of inertia (ability of object to resist changes in its rotational velocity)
w = rotational velocity (rpm)
I = k x M x R^ (M=mass; R=radius); k = inertial constant (depends on shape)
(in the above equations ^ means 'squared', eg: R x R)
Inertial constants for different shapes:
Wheel loaded at rim (bike tire); k = 1
solid disk of uniform thickness; k = 1/2
GC
Kinetic energy = sum of kinetic energy of individual mass elements that comprise the flywheel
= 1/2 x I x w^
where:
I = moment of inertia (ability of object to resist changes in its rotational velocity)
w = rotational velocity (rpm)
I = k x M x R^ (M=mass; R=radius); k = inertial constant (depends on shape)
(in the above equations ^ means 'squared', eg: R x R)
Inertial constants for different shapes:
Wheel loaded at rim (bike tire); k = 1
solid disk of uniform thickness; k = 1/2
GC
Last edited by Guy Croft on January 10th, 2007, 11:59 am, edited 1 time in total.
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First of all, I am impressed that some company is even quoting MOI, they always say weight which means very little..
Anyhow.. I've done just what Guy mentioned and drawn up a few Fiat flywheels in CAD software. Unfortunately this is not very accurate due to different materials, densities.. etc.. but it will get you a good ballpark and will be good to compare other flywheels derived from the same CAD software (I feel anyhow). I have compiled some of this info in a PDF here: http://www.millersmule.com/File%20Libra ... arison.pdf
and MOI on here is given in lb*in^2
Hope this helps,
-Jason
Anyhow.. I've done just what Guy mentioned and drawn up a few Fiat flywheels in CAD software. Unfortunately this is not very accurate due to different materials, densities.. etc.. but it will get you a good ballpark and will be good to compare other flywheels derived from the same CAD software (I feel anyhow). I have compiled some of this info in a PDF here: http://www.millersmule.com/File%20Libra ... arison.pdf
and MOI on here is given in lb*in^2
Hope this helps,
-Jason
-Jason Miller
Miller's Mule Machine and Design Inc.
Houston, Texas - USA
Miller's Mule Machine and Design Inc.
Houston, Texas - USA
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