Advanced upper stage energetic propellants

Abstract

The upper stage propulsion of spacecrafts is an intensive area of emphasis. In the past few decades, standard propellants have been worked upon and utilized. Cryogenic Propellants viz., Liquid Hydrogen, Liquid Oxygen are widely used for upper stages however, an aspect of concern is the high pressure cryogenic storage tanks that must be able to withstand high pressure thus making fuel tanks bulky needing heavy insulation to store Propellant thereby, reducing performance and practicality. The over-dependence on cryogenic propellants has necessitated active research efforts for efficient alternatives. As an attractive alternative, Nitrogen tetroxide and Monomethyl hydrazine (MMH) are used for many space applications owing to high specific impulse, extreme storage stability, and hypergolic nature. The combination is extensively used in orbital maneuvers, reaction controls, and launch vehicle propulsion. The present study details the role of energetic propellants using N2O4 and MMH as the base composition for enhanced upper stage performance. Selected energetic materials are tested with the base composition by using standard NASA-CEA complex chemical equilibrium program. The performance is evaluated in terms of variation in specific impulse and characteristic velocity. The work is motivated by the need of efficient space operations with attractive propulsive alternatives to minimize over-dependence. To validate the practical utility, the role of chamber pressure, supersonic area ratio and optimal Oxidizer to fuel ratio (O/F) is determined.