Expression for decellerating rotation animation
 

Hey, I'm making an animation and I need some help with syncing it.

What needs to happen is this; it starts spinning slowly, and accellerates for a while untill it is going at a certain speed, and then it starts slowing down, and comes to a stop.

This is the expression I have so far:
if (frame < 102)
group4.rotateX = (frame*frame)*0.15;

Where do I go from here??

EDIT: Never mind, I've done it :)
:banana:

try this, add attribute to your group name it RPM

if (frame == 1)
{group4.rotateX = 0 ;}
else
{ group4.rotateX += (( group.RPM * frame * 360 )/(30*60))/frame;}

just key the RPM attribute, 0 means it will not rotate.

got this stuff in highend3d.