Previously reported correlation exercises involving aerodynamic force measurements on Volkswagen and Pininfarina reference cars have been extended to include the MIRA full-scale wind tunnel, following recent significant modifications to the tunnel and the data reduction procedure. For the Volkswagen car, this represented a repeat of tests carried out prior to the modifications.
The results showed generally satisfactory correlation, for engineering purposes, between the MIRA closed-jet tunnel and the four European open-jet facilities at VW, Daimler Benz, Fiat and Pininfarina.
To obtain even closer correlation in order, for example, to ensure comparability of advertising claims regarding drag coefficients, improvements will be needed in respect of wheel mounting pads, blockage and ‘buoyancy’ corrections and the standardisation of vehicle test conditions.