the viking was roughly half the size, in terms of mass and power, of the v-2. both were actively guided rockets, fueled with the same propellant (ethyl alcohol and liquid oxygen), which were fed to a single large pump-fed engine by two turbine-driven pumps. the reaction motors xlr10-rm-2 engine was the largest liquid-fueled rocket engine developed in the united states up to that time, producing (sea level) and (vacuum) of thrust. isp was and respectively, with a mission time of 103s. as was also the case for the v-2, hydrogen peroxide was converted to steam to drive the turbopump that fed fuel and oxidizer into the engine. as its v-2 counterpart, it also was regeneratively cooled.