| Popis: |
There is a need to reduce cost and perform an optimization on smallsats and standardsats before options for a payload/bus/launch vehicle combination are selected. Bus manufacturers want naturally to protect their proprietary data; at the same time, a smallsat designer cannot decide on this combination without tradeoff analysis. Geosynchronous bus manufacturers realized, some time ago, that it was in their interests to release some of the payload trade-off curves to potential customers. This paper provides a methodology to reduce cost and optimize the selection of this combination, for Low & Medium earth orbits satellites. This generalized approach for elliptical orbits, is extended from a previous paper on circular non-GEO orbits. It provides equations for the net payload power and mass available to the system, for varying bus launcher sets, for elliptical (and circular) orbits, taking into account orbit eccentricity, mass to orbit, power generation/storage and fuel required for drag make-up. Some selected examples are provided for the payload power and mass for different launchers and the total payload equivalent mass at varying elliptical altitudes. This methodology is adequate for a first cut optimization, for elliptical LEO's and MEO' s, with direct injection launches. Further refinements require detailed knowledge of the power system as well as other data of a given bus, which are best evaluated with the bus manufacturers. |
