Chaparral 2J: The Ground Effect Car with Constant Downforce
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Chaparral 2J: The Ground Effect Car with Constant Downforce

Jim Hall created a car with inventive engineering and unheard-of downforce: the Chaparral 2J.

Few cars appear weirder than the Chaparral 2J roadster. In fact, the Chaparral 2J really looks like the front half of a car designed by someone without the money to finish the back half. Owner Jim Hall would heartily disagree with that statement. In 1968, Hall went on the hunt for a car that would revolutionize racing. He was looking for a way to add a tremendous amount of downforce to the vehicle without adding a tremendous amount of weight. Hall and his team had formerly tried just about every external design imaginable to increase downforce, but these gigantic wings and vents only added a fraction of the downforce that Hall was looking for. So, Hall went off the map in search of an idea way outside of normal, and found one.

The answer was in ground effects. In addition to the Corvette engine that powered the 2J, Hall added a snowmobile engine to the rear. Why? The two-cycle engine was linked to a twin fan assembly (visible at the rear of the car in the picture and more visible in the links). This assembly sucked the air out from underneath the car and essentially glued it to the road. The car was exactly what Hall was looking for. It had tremendous downforce, and it stuck to the road in any situation. Interestingly, the car's greatest advantage was in lower-speed corners where aerodynamics were greatly downplayed. Devices like spoilers only work to improve downforce when air is flowing over the vehicle at a high rate of speed. But since spoilers are external, they decrease the car's drag coefficient. Obviously, as rate of speed decreases, so does the amount of drag, but the downforce decreases with drag. This requires increasing care when entering a low-speed corner.

Hall's design threw all of these assumptions out the window. By utilizing a skirt around the car, Hall essentially created a pocket underneath the car for the fan assembly to suck the air out of. Because the fan assembly ran constantly, the car could essentially maintain similar downforce at all speeds. Also important were that external spoilers were no longer necessary, so the car's aerodynamics could be improved dramatically. The result was fantastic: activation of the assembly would drop the car several inches, and the car would continue to stick to the road as long as the device was on. As soon as the car was ready to race, it began setting records and monopolizing the pole position at all the races it entered.

Like many ingenious ideas, however, the 2J was too good to last. Other cars had no ability to compete with the car, so the FIA quickly found reasons to remove the car from the racing scene. The sliding skirts were found to violate aerodynamic rules, and the fan assembly had a tendency to suck up flotsam from the track and spit it back at drivers in the rear--which is where other race cars usually found themselves in proximity to the 2J. Regarding the car's disqualification, Hall commented, "If I come up with a better mousetrap that is within the guidelines of the regulations, than I ought to be able to use it." Chaparral cars did, however, compete well and earn a number of notable victories at popular endurance courses such as Laguna Seca in California and the Nurburgring in Germany. They left a legacy that was remembered fondly by many in the endurance racing community.


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