After the breakup of the Stratos III vehicle, inertial roll coupling was pinpointed to be the root cause. In order to battle the problem a propulsive roll control system was suggested to keep the roll rate under acceptable bounds. A restartable hybrid rocket engine using nitrous oxide and ABS plastic was proposed. 27 tests have been performed of which 10 were hot fires that had successful ignition. Analysis of this data yielded some boundaries of ignitability, given insights in promoting restartability and showed a low ignition delay of 100ms at a consistent stable ignition input power. Two tests featured helical ports showcasing control of the grain burn profile. In addition, a preliminary design tool was made and validated using the data of the hot fires. Modelled values for the feed system pressures and thrust output have been proven to be within ±10% of the experimental data.