This paper presents analysis of hypersonic base ows using the detached eddy simulation (DES) methodology.Unlike Reynolds-averaged Navier-Stokes (RANS) simulations, DES computes the dominant unsteady motion in the three-dimensional ow behind a vehicle, and thus results in a more realistic ow eld than RANS. Simulations are performed on carefully designed DES grids and the eect of grid renement in the focus region is studied. At the current conditions the ow in the near wake is transitional. Successive grid renement in this case reduces the magnitude of the eddy viscosity such that the DES solution on the nest mesh approaches direct simulation without a turbulence model. In the absence of signicant eddy viscosity, lowering of numerical dissipation is essential to achieve grid-converged solution.