How Chaotic Dynamics Drive a Vintage Grill-Room Spit

In 1943 Yves Rocard published an amazing book entitled "Dynamique Generale des Vibrations". Among a collection of mechanical devices that are studied with great care in the book, the so-called Bouasse-Sarda's "tournebroche" (rotary grill spit) is a fascinating two degrees of freedom device. What makes it interesting is that it stylises a wide class of forced parametric oscillators exhibiting a rich range of complex dynamical behaviours including fully deterministic chaos, a dynamic concept not popular in the forties and hence not yet discussed in Y. Rocard's book. Today's numerical tools offer a new possibility to revisit this amazingly simple but rich dynamical system.