# I Moment of Inertia of a Propeller?

1. Mar 5, 2017

### doggydan42

Is there an equation for the moment of inertia of a propeller? If so, what is it? If there isn't one, can I use the moment of inertia of a rectangular slab? Thank you in advance.

2. Mar 5, 2017

### BvU

Hello dd,

That's one approach. Another is to stay closer to the definition of moment of inertia and calculate $\displaystyle \int r^2\;dm$ (if you have enough shape information).

3. Mar 5, 2017

### Nidum

There is no general formula .

Quite easy to do though - just divide any one propeller blade into thin sections and sum up the individual moments of inertia numerically .

Then multiply by number of blades and add moment of inertia of hub .

Hub is just a solid of revolution so no problem doing that bit either analytically or numerically .