Thread: Momentum or Energy?

Given a disc of mass m containing two identical opposite opposing rocket nozzels on opposite sides of the disc, which are tangent to the outside of the disc, with an amout of propellant (of negligable mass when compared to the mass of the disc) contained inside the disc, and that propellant burns and the gas created flows equally to the two nozzels such that it will spin up the disc to some rotational velocity without causing any translation. Its now desired that we want to spin up the same disk to double the rotational velocity by the addition of more propellant (again of neglible mass when compared to the mass of the disc) while adjusting the combustion chamber and nozzels so that all of the propelant is burned and expelled in the same amount of time as before. Would the propellant have to be doupled- a momentum problem? Or would we n4 times the propellant - an energy problem?