PERFORMANCE OF ARIANE 5 UPGRADED VERSIONS USING DENSIFIED PROPELLANTS

The use of densified propellants, i.e., cryogenic propellants stored in the tanks at a temperature significantly below the boiling temperature at the relevant pressure, in considered for launchers belonging to the Ariane 5 family. The increased density allows to load more propellant on board, ultimately resulting in an increased payload. The identification of the appropriate level of subcooling is discussed, as well as the re-evaluation of engine performance (in view of the reduced propellant enthalpy content) in terms of effective exhaust velocity. The payload mass of the proposed upgrades is determined via a flight analysis tool. Also considered is the performance of a hypothetical launcher, outlined in a previous paper, adopting cryogenic liquid propellant strap-on boosters in place of the current solid propellant ones. Problems associated with the use of subcooled propellants are reviewed. It is found that the proposed configurations enable a payload increase in the range of 3 to 4%, which must be weighted against some additional costs for adaptation of the propulsion system in order to employ subcooled propellants; some elements are given in this regard.