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Axial force, side force and yawing moment are measured on each member of a three-vehicle platoon subject to crosswind conditions. The longitudinal spacing between vehicles is varied from 0 to 0.72 vehicle lengths in a large set of combinations covering both symmetric and non-symmetric configurations. Crosswind is simulated by yawing the platoon ten degrees with respect to the axis of the wind tunnel. Axial forces are significantly smaller for close-following. At a spacing of 0.1 vehicle lengths, the average axial force coefficient at yaw is diminished to about 61% of the value for a single vehicle at yaw. The air stream is redirected by the presence of the platoon so as to diminish side forces and yawing moments on trailing vehicles.

The purpose of this report is to experimentally determine the air flow through the cooling module (air-conditioning condenser plus engine radiator) of a Ford Windstar minivan when the van is operated at a fraction of a vehicle length behind a lead van. Pressures and temperatures are measured across the cooling module while the vans are in operation, and a standard calibration relates the pressure drop to the flow velocity through the cooling module. The Windstars are connected in tandem and driven on a test track at spacings of 0.22, 0.28, 0.38, 0.62, 0.88, and 1.0, expressed as fractions of the Wind-star length. For the purposes of the test, an override switch is installed to allow the close-following van to be operated either with both cooling fans remaining on or with both fans disabled. Air flow is expressed either as a volume flow, in cubic meters per second, or as the fraction of the flow for a van operating in isolation at the same forward speed.

The present study aims to document the drag reduction for a two-vehicle platoon by operating two full-scale Ford Windstar vans in tandem on a desert lakebed. Drag forces are measured with the aid of a special tow bar force measuring system designed and manufactured at USC. The testing procedure consists of a smooth acceleration, followed by a smooth deceleration of the platoon. Data collected during acceleration allows the calculation of the drag force on the trail-vehicle, while data collected during deceleration is used to calculate the drag on the lead vehicle. Results from the full-scale tests show that the drag behaviors for the two vans are in general agreement with the earlier conclusions drawn from the wind tunnel testsænamely, both vans experience substantial drag savings at spacings of a fraction of a car length.