Installation of a Rear Fan on RC Race Car Body to Improve Drag

Abstract

Lola style body 1:10 scale radio-controlled electric race cars are one of the most popular categories among enthusiasts in Thailand. These cars usually have wedge-like body shells which generate large downforces but with a large wake downstream contributing to large pressure drag. This work aims to improve the car aerodynamic performance by installing a rear fan in a similar manner to Gordon Murray Automotive T.50, which has not been attempted on an RC racecar before. Wind tunnel experiments are successfully conducted to evaluate the effects of the rear mounted fan with different rotor diameters and rotation speeds. Test results suggest that the car aerodynamic downforce enhancement by the rear fan is most effective at low Reynold’s number of 4.63×10⁴, where the downforce is observed to increase by 1,440%. Downforce increments at high Reynold’s numbers of 2.18×10⁵ and 3.72×10⁵ are less effective as increases of 104% and 33% are observed, respectively. Drag forces are, however, observed to increase at all three sample Reynold’s numbers. The highest increase in drag force of 242% is observed at low Reynold’s number and, 16.7% and 8% at high Reynold’s number. It can be concluded that the rear mounted fan helps improve the downforce through the extra suction under the body but does not reduce the pressure drag by narrowing the wake as had been anticipated.