does anyone know how to make a rotordown wash effect in Carrara or where I can get one?
HI mhscspo :)
If you mean the reaction of other objects to the effect of the down-force from the helicopter, I would look at using the Point force, and perhaps the Animation option in the Plant system ( for tree's, plants, grass ..etc)
You can set that to animate a Wind in a specific direction.
You can also use "Dynamic Hair" as grass, for small areas, and this will react to forces in the scene.
For Bigger objects, you can use Physics and forces, or just animate some Vibration using a couple of key-frames, and the Oscillate, or Noise tweeners.
Hope it helps :)
Thanks, I'll give it a try...