Hey Mike,
Without measuring the shafts and calculating the second moment, there is
no way to say which shaft is easier to accelerate. You could be right
that the aluminum shaft still comes out ahead despite a thicker wall,
but the OD is really quite a bit more than the steel, which levels the
playing field again. In the calculations for inertia:
4
(pi) x density x Length x (Outside Radius-Inside Radius)
I= ---------------------------------------------------------
2
The R is the shaft radius, density is material density, Length is shaft
length, I is inertia about the central axis. You can see that Radius is
to the 4th power which makes it 4 times more critical to the inertia as
does the material (density).
As per usual, anybody whose brain is full, head hurts, or brain exploded
messily may be excused.
Cale
> Wheels are turning.... I see your angle, but even if the aluminum is
> thicker, it is still lighter than the stock steel. So the rotational mass
> of the aluminum is still less than the smaller steel, so the force required
> to overcome the inertia is still less, thus allowing more horses to go to
> the rear end. Ever seen carbon fiber driveshafts. They have a large OD,
> but they are extremely light and strong. Less rotational mass (weight),
> less affect by inertia, less power wasted turning the driveshaft.
>
> Mike
>
> __________________________
> mschwall@flash.net
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