A theoretical and experimental study has been undertaken, under ESA contract, by a team including GMV, the University of Bologna and EADS-Astrium, to assess the feasibility of an entry descent and landing (EDL) vehicle based on unpowered rotary decelerator. A deployable rotor with telescopic blades is considered, aimed at replacing all the standard deceleration devices for a descent module (parachutes, airbags, and retrorockets) except for the heat shield, with Mars as the main planetary target.This paper deals with the aerodynamic assessment of the proposed vehicle configuration. The objectives are twofold. First, a proof of concept of the main autorotation related events, viz. blades deployment from folded configuration in supersonic or transonic regime and telescopic blades extension in subsonic regime, is experimentally analyzed. Second, a characterization of the vehicle performances in terms of aerodynamic drag,