Aerodynamics of Timber Trucks - a Wind Tunnel Investigation

There is a need for reducing fuel consumption and thereby also reducing CO2 and other emissions in all areas of transportation and the forest industry is no exception. In the particular case of timber trucks special care have to be taken when designing such vehicles; they have to be sturdy and operate in harsh conditions and they are being driven empty half the time.

It is well known that the aerodynamic resistance constitutes a significant part of the vehicles driving resistance and four areas in particular, front of vehicle, gap, side/underbody and rear of the vehicle contributes about one quarter each.

In order to address these issues a wind tunnel investigation was initiated where a 1:6 scale model of a timber truck was designed to operate in a 3.6 m wind tunnel. The present model resembles a generic timber truck with a flexible design such that different configurations could be tested easily. During the tests the model was swept +/− 10 degrees in order to account for the yaw angle as well as catching possible effects from asymmetric flow conditions. Furthermore, by using a yaw angle sweep, a wind averaged drag coefficient could be measured.

The baseline configuration was compared with the different aerodynamically improved configurations and an improvement of more than 200 drag counts of the wind averaged drag coefficient was readily achieved.