Effect of engine, tank and propellant specific cost on single stage recoverable booster economics

Reusable first stages using hydrogen-oxygen, hydrogen-fluorine and kerosine-oxygen are compared with non-reusable stages using a solid in addition to the liquid combinations. The criterion used for comparison is the minimum specific cost of the "loaded and ready for launch" stage cost per unit of stage payload mass. A closed form relationship is used in which the empty stage mass without payload is taken to scale in part proportional to propellant mass, and in part to mass flow rate. The stage specific cost is proportional to specific cost of engine (or nozzle) tank and propellant. In the second part the hydrogen-oxygen combination is consiaered,in more detail. The sensitivity of the results to changes in various specific costs including that of refurbishing are described. Throughout, the stage velocity increments are compared in the 3000-6000 metres/second range with losses.