3D40.65 - Austrailian Bullroarer
Produce a loud sound with a small paddle on the end of a string, designed to rotate and emit a roaring sound near 85 Hz.
Take the handle of the device and spin it in a vertical plane.
RE: Sutton S-143.The "bull-roarer" operates by the autorotation of a flat plate in an air stream. As it is whirled, it twists the string until it can twist no farther, then it untwists. The loud noise that it produces is due to the generation of eddies in the air.