200-foot skidpad test Options

[reverie]

The standard 200-foot skidpad test. What equipment is needed? I figure we need a nice big surface in a parking lot somewhere, and then mark off the 200-foot circle in chalk (using a 100-foot rope and a center point), and then use a/x cones to make the circle more visible. And then each car goes around the circle of cones in a counter-clockwise direction..

But how do we measure the G's? (IMG:style_emoticons/default/huh.gif)

[VegasRacer]

I was just sent this PM from a non-posting 914Club member.

A skidpad with a 200 ft. diameter would have a circumference of 2(pi)(radius) ~ 628.3 ft. Divide this distance by the time it takes the car to make a complete circle around the skidpad and you get the average speed. Square the average speed and divide that number by 100 ft and you get the average centripetal (lateral) acceleration around the skid pad. Divide that number by 32.2 to get the figure in g’s.

For example, if it takes a car 12 seconds to go around the skidpad, then the average speed would be 52.4 ft/second and its square would be 2745.8 ft^2/s^2. The average lateral acceleration would be [2745.8 ft^2/s^2] / 100 ft = 27.5 ft/s^2 or about 0.85 g’s.