Abstract: A low-cost, liquid-propellant rocket launch vehicle having a central pod that carries an optional final-stage rocket engine cluster, and having additional engine clusters arranged in diametrically opposed pairs of clusters. The pairs of clusters are burned and separated in a staging sequence until the final stage is reached. In the presently preferred embodiment, there are three pairs of engine clusters arranged in a hexagonal configuration about the central pod and each engine cluster contains seven identical engines. The engines are made from light-weight, low-cost materials, without gimbals or other moving parts. Steering of the vehicle is effected by differential control of the engine thrusts of selected engines, using duty-cycle modulation of a plurality of on/off propellant supply valves and, additionally, control of other on/off valves controlling the supply of an inert cryogenic fluid to secondary injection ports on the engine.