I take it that the specific impulse would be measured in some reasonable unit like Newton metres, or foot pounds?
Or maybe, it's more like a KE thing?
Or is it a Joules thing? It's been a while since last I was in Mr Stirlings physics class.
Yes to the above, just pick your favorite measurement sytem.
For the more common expression you might try
KE= 1/2 * Polar moment of inertia * rotational speed squared.
If I told you 1 million or 10 million foot-lbs would it make any difference?
It's sure to go through anything on the airplane that gets in its way