Experimental Aerodynamic Characterization of a Rotary Entry Vehicle for Mars Landing

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. In particular, a deployable rotor is considered, aimed at replacing all the standard deceleration devices for a descent module (parachutes, airbags, and retrorockets) except for the heat shield. Mars is assumed as the main planetary target. The concept of rotary entry vehicle is not completely new (see, for example, [1]), at least for Earth re-entry, but, due to the low density of Martian atmosphere, really large rotor radius are needed in order to provide enough deceleration force. This leads to a particular concern about rotor stowing during the early entry phases. The configuration selected to overcome this is a rotor with foldable telescopic blades, mounted on the top of a conventional Viking-shaped probe. This paper deals with the characterization of aerodynamic properties of the proposed configuration under two aspects. The first one is a proof of concept of the main autorotation related events, namely, blades deployment from folded configuration, in supersonic regime, and telescopic blades extension, in subsonic regime. Besides that, measurements of the vehicle performances in terms of drag, lift to drag ratio and rotor angular speed is also explored. The facilities selected for the experimental campaign are VKI S-1 wind tunnel at Von Karman Institute of Fluid Dynamics for supersonic/transonic regimes, and the wind tunnel of the Applied Aerodynamics Laboratory at University of Bologna for subsonic testing. Two dif-ferent models have been designed which separately reproduce the rotor deployment and blades telescoping mechanism: this paper describes the development and testing of the subsonic hardware demonstrator.