The effects of aerodynamic design on lightweight human powered vehicles

The Royal Automobile Club of Victoria (RACV) Energy Breakthrough is held in November annually in Maryborough, Victoria, Australia. It is contested by primary and secondary school teams, who are required to build lightweight (usually bicycle based) vehicles in two principal categories: solely human powered and petrol/electric/human powered hybrids. The main competition is a 24 hour endurance event. The bodywork of Energy Breakthrough vehicles typically ranges from streamlined to bluff, and many teams do not consider aerodynamics at all. In this competition it is expected that the outcome will be primarily based on physical strength and stamina of the riders leaving aside such factors as mechanical breakdown or accident. When comparing aerodynamic design against the fmal results, it was found that no high-drag vehicle achieved more than 60 percent of the winner's distance in any class. It can be concluded that for such lightweight vehicles where rolling and drivetrain resistance is low, aerodynamic drag has a major influence on the overall results despite the average speed of the leaders being only approximately 45 kmh.