Solar Prototype for Shell-Eco Marathon Race

Apollo is the name of a solar prototype vehicle of Politecnico di Milano (Technical University of Milan) that has been conceived and employed for the Shell Eco-marathon® Europe competition (SEM). The paper introduces the concept design, the detailed design, the construction, the indoor tests, the successful employment at SEM and the end-of-life of the prototype. Apollo is a three-wheeler with a single driving and steering wheel at the rear. A wing with solar cells provides part of the electric energy required for running. The conceptual design started from the accommodation of the driver inside the vehicle. A number of iterations focusing on CFD (computation fluid dynamics) and wind-tunnel tests allowed to refine the total drag to less than 2N at 35 km/h. The tyre characteristic was measured on a drum. The camber of front wheels was set to 4 deg which provided the least rolling resistance. The powertrain, with an extremely simple engagement of the reduction gear, was designed to fit into the rear wheel, properly designed. A Maxon® electric motor is adopted. The CFRP (carbon fiber reinforced plastic) body has been designed by FEM (finite element model) and the body weight is just 8.9 kg. Wheels have been optimized for weight saving. Apollo, in 2011 at Lausitz ring during SEM Europe, was able to run an equivalent distance of 1108 km with 1 kWh only, establishing the best performance ever attained for such kind of prototype vehicles at SEM. Such a performance is two or three orders of magnitude better than the one of current electric production road licensed vehicles and sets an unsurpassed limit for such kind of applications.