If you can be bothered with 4 minutes of film, here is a demo using a radio-controlled model; the actual phenomenom is at about 2:40, but he explains how he is going to set it up first.
http://www.youtube.com/watch?v=0Kz_gOWaR7Y
As for China Beach (never heard of it until today!), I watched the opening credits on youtube but none of the helo shots seems to last long enough.