Air Whistles? Anybody?
Here's a good source for these whistles...
Go to your favorite toy store, and buy yourself one of those Vortac footballs with the fins on back. Some have whistles embedded in the ball itself, and can be dug out and placed on your plane. I think the balls are 5 or 6 bucks, but they have 3 or 4 whistles on 'em. I have a couple on my H9 US120. Drives people crazy.