Search Results

In the last few years, extended research has been performed by car manufacturers in order to improve the handling, safety and comfort of ground vehicles. As a results, modern cars are equipped with many electronic automatic control devices. Among them the yaw-control system is probably the most critical and challenging. Road vehicles are complex non-linear dynamic systems, and the control of some of their motions needs the development of adequate full-vehicle models. In this paper a complete dynamic model of a road vehicle is derived and discussed, which can be suitably used to develop the new concept of “performance-oriented” yaw-control system.

The aerodynamics of the 360 Modena features a “flat” underbody with large extractors that give a high downforce but generate constraints in terms of chassis design. As a result, the choice of a longitudinal gearbox and short suspension wishbones was almost mandatory in order to leave enough room for the rear extractors. For these reasons, it became necessary to develop the vehicle dynamics taking into consideration the combination of aerodynamics, suspension kinematics, damping control, tyre characteristics and production technologies. This paper addresses the problems related to the chosen vehicle configuration and the technical and technological solutions adopted to solve them.

As part of the general program for comparing leading European automotive wind tunnels, three reference cars derived by Volkswagen (VW), Pininfarina (PF) and FIAT Research Center (CRT) from production models, were tested in different configurations. This report contains the result of tests carried out on a CRF reference car in CRF, VW, DB and PF wind tunnels as well as on the road. The wind tunnel tests of the car in 7 different configurations show a fairly good agreement particularly for the drag coefficients measured in the various tunnels. Road tests were carried out with the car in three configurations at constant speed (measuring front and rear axle lift, body pressure and visualising the wake) and in coast-down (measuring aerodynamic resistance). The results obtained proved that road driving conditions with no side wind or turbulence are correctly simulated in wind tunnel tests.

This investigation was performed with the purpose of comparing the arodynamic drag of an automobile as measured in a full-scale wind tunnel with the drag as measured on the road. A definition of the drag coefficient as measured both on the road and in the wind tunnel is given in advance in order to allow a comparison to be made between the two operating conditions. Three medium size european cars were selected, one notch-back type and two hatch-back types. Road testing was mainly based on the coast-down method. The total resistance was determined by statistical analysis of the experimental results. The theoretical basis and the specifications of the procedure are investigated and justified. Additional outdoor and indoor tests were carried out in order to isolate the aerodynamic drag. The wind tunnel tests were conducted on the same cars fully equipped as tested on the road and in the same speed range.