Hi,

I am trying to achieve the effects of rotational acceleration and deceleration.

I am rotating an object and want it to spin up and down like a propeller starting and stopping.

I am attempting to do is in a transform node's rx,ry,rz field using $FF, sin(), $F, $NFRAMES but couldn't get it to look right.

Any ideas ?

Regards

sin($F * speed) * size.
Speed being how fast, size being the size of the value, so to make something rotate back and forth i might do: sin($F) * 180, if I misunderstand what you want elaborate. If you want to make It stop and start by your command look into chops. Or key frame it (I'd avoid this).