Abstract : A type of Surface-to-surface missiles used by the Thai military mainly used solid propellant in a relatively simple propulsion system. Ignition of the propellant is initiated by hot gases passing through holes drilled at an angle along the surface of an embedded ignition case. This paper considers the effect of the angle of these holes on the flow and pressure of hot gases impacting on the solid propellant. Both cases of constant angle of the holes and varying angle are considered. The investigation has been carried out by the finite volume method using the program ANSYS FLUENT.