Rotating Translating Cones

Abstract

A first attempt has been made to confirm experimentally a theoretical concept, recently published, involving a rigid cone rotating about its long axis under still water: it should tend to translate along that axis blunt end leading and apex trailing. Two identical hollow cones, neutrally buoyant, with equal weights attached to the apexes, were released simultaneously at the surface of a swimming pool. One cone had a thin light weight spiral vane vertically attached to the cone’s outside surface in order to cause it to rotate as it sank. Several trial runs were made in the shallow and deep ends of the pool, and in every case, the non-rotating cone without a vane hit the bottom of the pool first. These comparisons qualitatively and indirectly validate the prediction.