Tilt-A-Whirl is one of the best-known flat rides, designed for commercial use at amusement parks, fairs and carnivals in which it is commonly found. The rides are manufactured by Sellner Manufacturing of Faribault, Minnesota.
The Tilt-A-Whirl is a platform-type ride, consisting of seven freely-spinning cars that hold four riders each, which are attached at fixed pivot points on a rotating platform. As the platform revolves, parts of the platform are raised and lowered, and the resulting centrifugal and gravitational forces on the cars cause them to randomly spin in different directions and at variable speeds. The weight of passengers in these cars may intensify or dampen the spinning motion of the cars, adding to the random nature of the motion. Mathematicians call this random nature chaotic motion. Sellner requires all riders to be 46 inches or taller unless they ride with an adult; however, no infants are allowed.
Physicists Bret M. Huggard and Richard L. Kautz came up with a mathematical equation that approximates the motion of the Tilt-A-Whirl. Although it was without knowledge of chaos theory that Herbert Sellner invented the ride, in his patent text he clearly demonstrates an appreciation of chaos -- "A further object is to provide amusement apparatus wherein the riders will be moved in general through an orbit and will unexpectedly swing, snap from side to side or rotate without in any way being able to figure what movement may next take place in the car."
Family legend states that Herbert experimented with a chair placed on the kitchen table. Herbert's son Art sat in the chair, and Herbert rocked the table back and forth.
The earliest Tilt-A-Whirls were constructed of wood, powered by a gas motor, and featured nine cars. Today, the ride is constructed of steel, aluminum and fiberglass, is powered by seven small electric motors, and features seven cars.
A new Tilt-A-Whirl costs approximately USD $300,000 to purchase.
The oldest currently operating Tilt-A-Whirl is a 1927 model, still traveling with Tom Evans United Shows in the midwest. Between 600 and 700 Tilt-A-Whirls are still in operation.