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The extensive use of wind tunnels in the aerodynamic development of race cars started during the 1970's. At this early stage, large gains in performance could be achieved using simple models and standard testing techniques. However, with continuing development the gains that could be achieved became progressively smaller as the overall aerodynamic performance improved. This has required the development of complex, fully representative models which include, for example, correct radiator simulation and working suspension. The need for detailed aerodynamic data has resulted in the employment of advanced testing techniques. In addition to accurate force and surface pressure measurements, the flowfield characteristics around the car are measured using a laser doppler anemometry system. This paper presents a description of current testing techniques employed in the development of the Penske Indy Car during tests in the University of Southampton 3.5m x 2.6m wind tunnel.

The aerodynamic characteristics of an Advanced Ground Transport vehicle, Electrodynamic System, have been investigated. A series of wind tunnel tests were undertaken using a 1/13th scale model of 1.423m length and 0.286m width at a speed of 26m/s which produced a Reynolds number per unit length of 1.8*106. This compares with a full-scale Reynolds number of 7.6* 106 per unit length. The overall forces and moments generated by the model were measured using an internal six-component strain gauge balance. Relative ground clearances from 0.4 to 0.011 of model height were tested. The typical operational ground clearance of a vehicle of this type is 0.06 of model height. Extensive surface pressure plotting was also undertaken.

A system capable of measuring the time averaged surface pressure distributions on rotating model propeller blades has been developed. A wide range of test conditions have been investigated and results displaying the effects of changes in blade setting angle, advance ratio and number of blades on the blade surface pressures are presented. In addition, the system has been used to experimentally investigate the influence of nacelle type afterbodies on the propeller blade pressure distribution.