Occupant Compartment Updates for Side to Side Vibration in a Fuel Funny Car 2008-01-2969
Nitro Fuel Funny cars have 7-8,000 hp and travel 330 mph in a quarter mile. These cars experience extreme forces in normal operation. One phenomenon familiar to drag racers is tire shake. Mild cases can cause loss of traction and vision. Extreme cases can cause injury or death. In March of 2007, a study and subsequent revision of the passenger compartment in a Fuel Funny car was performed after a fatal accident due to extreme tire shake.
Tire shake on a drag race car normally occurs when the force on the rear tire causes the tire to roll over itself causing a loss of traction and side-to-side vibration. In other cases, if the tire fails at high speed, the tire may partially separate, causing an extreme vibration in the cockpit of the car. The vibration may set up a harmonic in the chassis, which is transferred to the driver since the rear end is bolted directly to the chassis with no suspension to absorb the energy. The authors of this paper studied the effects of extreme vibration to the occupant compartment of a Fuel Funny car. Component testing of headrest and seat foams, seat belts and head and neck restraint were done to determine the effectiveness of each of these items in the system. An entire occupant system was developed using information from sled testing, linear accelerator testing, laboratory tests on the seat belt materials and mathematical modeling of the driver undergoing side-to-side vibration. The system was designed and placed into service in a 3 week period. New rules were subsequently introduced by the National Hot Rod Association (NHRA®) to mandate the use of many of the updates in this system for all of the Pro Funny Car and Dragster competitors. The system has been tested by drivers on the track with outstanding results, including an incident that was exactly like the previously fatal accident.