Using the Simulation

Using the Barrel Ride Simulator is easy. The simulation screen is divided into two sections. The section on the left is the animation. The barrel is drawn to scale and spun. The rider sits inside the barrel and spins with the spinning barrel. Current values of the three modifiable parameters - barrel radius, barrel period, and rider mass - are displayed above the barrel. The animation that you view is based on these three values.

The section on the right of the screen includes the Parameter Input panel and the output displays - speed, acceleration, force, thrill, and safety information along with a control panel for controlling (Play, Pause, Forward, Reverse, and Reset buttons) the animation. The Parameter Input panel can be accessed at any time by pausing the animation and tapping on the Make ∆es button. Use the arrows to modify values of radius, period, and mass. Then tap on the Let's Try It! button.  Press Play and view the animation and output displays. Give attention to the Safety and Thrill displays in the bottom right of the screen.  Your goal is to find a range of parameters that lead to good safetey and thrill. When you're ready to make changes, pause the simulation and tap on the Make ∆es button to modify the input parameters.

 

Understanding the Results

Rider thrill is tied to the number of Gs experienced by the rider. The number of Gs is calculated as the ratio of the force of the wall on the rider (F_norm) divided by the force of gravity.  A value of 1.0 for the number of Gs would be equivalent to laying on your back on your bed; that's not too thrilling and hardly worth the ride ticket.  As the ratio F_norm / F_grav increases, the thrill factor increases. However, there is a catch. There is a certain danger associated with a high number of Gs. Blood flow through blood vessels is interfered with and causes a number of potential hazards - loss of consciousness, black outs, burst blood vessels, aneurysms, detached retinas, and more.  So while increasing the number of Gs can result in a thrilling barrel ride, it can also result in an unsafe barrel ride. We have used pictures of Colonel John Stapp who was the first to study the physiological impact of varying number of Gs.  (Learn more here.)

A high number of Gs is just one of the two safety concerns. The second safety concern is too low of a rotation rate resulting in small normal forces and insufficient friction to hold the riders up. Since a barrel ride drops the floor out from under the riders, there must be sufficient static friction force between the rider and the wall in order to counteract the weight of the rider and hold her in position during the ride. With too little friction force, the rider will fall downward. It's not a tremendous hazard since there's still a floor 1-2 meters down but it's not likely to enhance a rider's sense of safety and satisfaction if they start falling down the wall.