The principle seems pretty simple. I used a Vertex Circle. Applied a different (Rough Sea) texture Added that rough sea texture into the displacement tab and adjusted displacement. Added Spin (Modifier Tab) Getting that circle to track in relation to the helecopter movement should not be difficult.

BUT, I can not seem to be able to work out, in Carrara, to do a  circular gradient where the edges would gradually soften off to clear.  Maybe Mark can help?

bwtr