Much attention has been paid in recent years to the enhancement of automobile performance and the improvement of fuel consumption at high speeds. Accordingly, it has become necessary to acquire a precise grasp of automobiles aerodynamic characteristics [1, 2, 3, 4, 5]. Compared with automobiles, however, the general level of interest in the aerodynamic characteristics of snowmobiles has remained low. This relative lack of interest is attributable to the fact that, because the area of the front projection of a snowmobile is comparatively small and the vehicle itself is very light, little emphasis has been placed on fuel economy. Moreover, it is attributable to the facts that improvements in aerodynamic characteristics of snowmobiles do not produce the dramatic effects that they do in automobiles, and finally because of the lack of strong demands in society for such improvement.
In reality, however, aerodynamics are playing an important role in the world of snowmobiles and contributing greatly to enhancing operating stability at high-speeds, comfort and engine cooling performance. This report is based upon tests in which we attempted to obtain quantitative measurement of the aerodynamic flow around a snowmobile by integrating technology for viewing aerodynamic flow with digital image processing technique [6, 7, 8, 9, 10]. By measuring these results and aerodynamic characteristic values, we aimed to obtain the optimum shape for a snowmobile with excellent windbreaking characteristics.