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A. brief survey of vehicle dynamics and aerodynamics papers pertinent to open wheeled racing cars is presented. In this work, the aerodynamics of Indy cars have been studied from both a lift and drag point of view. A standardized definition of lifting area for ground effects vehicles and performance observations made through the use of radar and track simulations were used. Values for negative lift magnitude were determined, lifting area was photogrammetrically measured, and a lift coefficient appropriate for Indy cars was developed. Drag area, also obtained photogrammetrically, and drag coefficients were developed. Mechanical measurements of vehicles and wind tunnel experiments were used to estimate total drag and subsequent values for drag coefficients. These values correspond with energy balance calculations based on available engine power. A sensitivity study of the performance parameters of Indy cars was performed, with emphasis on enhancing top speed.

The relatively fragile nature of racing tires, coupled with the inevitable track debris which results from racing accidents, ensures that racing drivers will routinely experience conditions involving flat tire vehicle dynamics. We define flat tire vehicle dynamics as a situation which requires the driver to provide steering and/or braking and acceleration control while the vehicle is running on one or more tires which have dramatically reduced tire pressure. In the present work, we simulate the handling and braking vehicle dynamics which occur in the presence of a single flat tire on the vehicle. The flat tire was simulated via drastically reduced cornering stiffness, partially reduced limiting frictional capability and increased rolling resistance, and was alternatively simulated on both the front and rear axle. No simulations were conducted with more than a single flat tire because multiple tire failures which do not involve an actual accident contact and/or damage are rare.

The current performance of a top fuel (T/F) dragster racing car is very high. The cars can accelerate from a standing start to well over 330 mph (528 km/h) in < 4.6 seconds! The engine of a T/F dragster can make considerably more power than can be put down to the track surface. Intentional clutch slippage prevents wheelspin for most of the ¼-mile (0.4 km) standard length racing run. Even though the drive tires used are highly specialized and specifically designed for this type of racing environment, more traction is needed. To create more traction, especially during the second ½ of the run, external wings have been employed by the designers of such cars. The size and configuration of the wings is limited according to sanctioning rules. Recent wing failures and accidents have made other options for the creation of downforce appear attractive. In the present work, we consider the potential for using the shape of the car itself to create the required down-force.

Coast down testing with full-scale vehicles on level and inclined roads offers an inexpensive approach to road load determination and, in particular, aerodynamic force evaluation, provided that drag component extractions can be accurately achieved under random instrumental disturbances and biased environmental conditions. Wind tunnel testing of large vehicles, especially truck/trailers, to establish their aerodynamic drag is costly and also may produce questionable results when the effects of the moving road, blockage, wake/diffuser interaction, and rotating tires are not properly simulated. On the road, testing is now conveniently and speedily carried out using GPS-based data acquisition and file storage on laptops, allowing instantaneous on-board data processing.

In the scientific design of racing facilities and cars, a strong interplay exists between the aerodynamic characteristics permitted by the vehicle formula and the banking present at each track. We explore this relationship and in particular the sensitivity of various car and track combinations to changes in nominal values for banking and aerodynamic performance. Specific example calculations for NASCAR and IRL/CART vehicles and tracks are given.

When undertaking investigations into the aerodynamic behavior of automobiles using scale models in a wind tunnel, Reynolds number dynamic equivalence is often difficult or impossible to obtain. The boundary layer transition from laminar to turbulent flow thus does not occur at a point on the model which corresponds to the transitional location on the real vehicle. To improve results obtained in such tests, roughness elements can be applied to the scale model to be tested and the transitional position of the boundary layer manipulated to correspond to the position of transition on the actual vehicle of interest. This paper describes such techniques and illustrates their use.