AN ANALYSIS OF PAYLOAD GROWTH FOR MAJOR US AND EUROPEAN LAUNCH VEHICLES

Logistic S-curves are fitted to the progression of payload versus time for the major unmanned launch vehicles in the current United States a nd European fleets. The results are used to infer the degree to which each vehicle family has approached its predicted payload limit, and th e appropriate policy implications are discussed. The study uses well-k nown methods for fitting the data, and discusses several other figures of merit that may be of possible use as new vehicles mature, or as ad ditional information can be gathered regarding historical vehicles. It has been found, for example, that U.S. launchers are generally very c lose to their unique ''point of diminishing returns,'' whereas the Eur opean launch vehicle family, the Ariane, can be expected to undergo si gnificant growth in the next several decades. The implication is that, if additional payload growth is desired for these U.S. launchers, con tinued evolutionary design changes must be abandoned in favor of more revolutionary changes, with an associated increase in research and dev elopment effort and cost.