American Institute of Aeronautics and Astronautics 1 Aerodynamic Measurements in the Mars Wind Tunnel at Tohoku University M. Anyoji, K. Nose, S. Ida, D. Numata, H. Nagai and K. Asai Department of Aerospace Engineering, Graduate School of Engineering, Tohoku University, Sendai, Miyagi, 980-8579, Japan Pressure-Sensitive Paint (PSP) technique has been applied to measure pressure distribution on airfoil models at low Reynolds number (Re = 4.1x10 4 - 4.3x10 3 ) in the Mars Wind Tunnel (MWT) at Tohoku University. In this study, the capability of PSP for pressure measurement was evaluated with a particular emphasis on its applications to thin airfoil models. The obtained results show that PSP can clearly visualize pressure distributions on the airfoils, allowing us to analyze a behavior of the separated shear layer on the airfoil including laminar-to-turbulent transition and reattachment. A comparison between the PSP and balance measurements indicates that the evolution of a laminar separation bubble over the airfoil surface has a strong effect on the lift and drag characteristics. It has been also verified by this experiment that, using the proposed method for temperature correction, pressure distribution can be obtained quantitatively even on thin airfoils. Nomenclature c = Chord length, m C d = Drag coefficient C l = Lift coefficient C p = Pressure coefficient I = Luminescence Intensity K SV = Stern-Volmer constant P = Static pressure, Pa P 0 = Total pressure, Pa T = Static temperature, K T 0 = Total temperature, K M = Mach number Re = Reynolds number α = Angle of attack, degree α(Τ) = Temperature-correction factor γ = Specific heat ratio x = Distance from a leading edge, m Subscripts ref Reference I. Introduction he idea of Mars exploration by a Mars airplane with fixed wing 1-4 has been considered as a new and attractive approach to obtain academically interesting data about the Martian surface and atmosphere. Mars airplanes can get higher resolution data than orbiting satellites and can provide larger spatial coverage than rovers. For the optimal design of a Mars airplane, it is important to predict the aerodynamic performance with sufficient accuracy. However, the design of Mars airplane has major aerodynamic issues because the flight conditions on Mars are very different from those on the Earth. The Martian atmosphere is mainly composed of CO2 and has lower density and lower temperature than the earth atmosphere. This leads to that a Mars airplane has to perform a flight at low Reynolds number (Re = 10 4 to 10 5 ) and T 49th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 4 - 7 January 2011, Orlando, Florida AIAA 2011-852 Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.