The Epsilon Launch Vehicle, successor of M-V rocket which conveyed "MUSES-C (Hayabusa)," is currently under the development in Japan. The Epsilon is also designed for sending scientific satellites to outer space and its first flight is scheduled to be in 2013. In this study, by conducting both numerical simulations and wind tunnel tests, the aerodynamic characteristics and associated flow features of the Epsilon Launch Vehicle are extensively investigated at Mach 1.5. The results provided are axial/normal/side forces, pitching/yawing/ rolling moments, detailed three-dimensional flow structure, along with effects of Reynolds number (between wind-tunnel and flight conditions), Skin Stringers (small devices on the main body), and difference from another configuration called "NextGenEpsilon." This set of data includes unavailable ones at either the experiment standalone or the actual flight. Magnitudes of computed aerodynamic coefficients are in good agreement with the experiment and within the design criteria. According to the results, axial force is not affected by those above-mentioned factors, but local normal force is influenced around Skin Stringers by Reynolds number, and rolling moment can change even its sign. Detailed M x = rolling moment, (y-y cg )f z -(z-z cg )f y ] [N·m] M y = pitching moment, (z-z cg )f x -(x-x cg )f z ] [N·m] M z = yawing moment, (x-x cg )f y -(y-y cg )f x ] [N·m] p = static pressure [Pa] Pr = Prandtl number, 0.72 [-] q = dynamic pressure [Pa] Re = Reynolds number [-] S = reference area, πD 2 /4 [m 2 ] T = temperature [K] u, v, w = velocity components in Cartesian coordinates [m/s] x, y, z = Cartesian coordinates [m] x cg , y cg , z cg = center of gravity coordinates, (0.6363L, 0, 0) [m] x n , y n , z n = normal vector components in Cartesian coordinates [-] = angle of attack [deg.] = slip angle [deg.] = roll angle [deg.] = specific heat ratio, 1.4 [-] = thermal conductivity [W/(m·K)] = (molecular) viscosity [Pa·s] = density [kg/m 3 ] Subscripts FL = flight condition F = forebody t = turbulent WT = wind-tunnel test condition ∞ = freestream value 0 = initial or stagnation value American Institute of Aeronautics and Astronautics 4