A rocket engine system including a coolant source containing a coolant fuel. The coolant source for providing the coolant fuel to a first surface of a wall partially defining a combustion chamber of a rocket engine, and the coolant fuel provides film cooling of the first surface of the wall. An oxidizer source for providing an oxidizer to a second surface of the wall. A monitor configured to control flow of the coolant fuel and the oxidizer, and to ensure that a stoichiometry of a combination of the coolant fuel and the oxidizer, after the coolant fuel has completed the film cooling of the first surface of the wall, is appropriate for generating a combustion of the combination of the coolant fuel and the oxidizer.