Although the battle against excess weight was won by the body work manufacturers, it was lost again through more safety and comfort, the search for a streamlined shape counts to the successes. Although, there are tendencies to once again, gamble away the saved energy through larger cross-sectional areas, indeed, the drag coefficient, which is a pure value of the aerodynamic shape, could be lowered in the next 40 - 50 years by 0,4 - 0,5 to under 0,3. This is also very important, because with modern vehicles, even at much less than 50 km/h, the air resistance exceeds the rolling resistance and then increases to the square of the speed.
In the model in the above picture, it is shown how the value is determined. The vehicle is placed on a movable base-plate, in a turbulence-free air flow, whose speed can be exactly adjusted. Not only the type of flow is important, also the width and height of the tunnel must be sufficient. If one now determines, how much force is to be applied to the base-plate or to the vehicle, one can, with a given cross sectional area, calculate the drag coefficient.
cartecc.com Top of page Index