The impingement of hot rocket motor plume inside a canister is simulated numerically by solving three-dimensional Reynolds Averaged Navier–Stokes equations using commercial software. The computed methodology is first validated for cold flow jet impingement in a circular tube for different chamber pressure and the simulations captured all the finer aspects of blow-by flow conditions as reported in the literature. A very good comparison is obtained between experimental and numerical surface pressure distribution. The validated methodology is applied to simulate the hot launch of a missile from a canister. It is observed that for low annular gap between missile body and canister the motor plume interaction became intense and gave rise to a very significant base drag which may constrain the motion of the missile inside the canister.