Effect of propellant temperature on the specific impulse liquid apogee engine

The first and second generation 490N bipropellant apogee engine uses nitrogen tetroxide oxidizer and monomethydrazine fuels,which are radiations and fuel-film cooled thrusters with impinging unlike doublets.By now,more than eighty engines have been hot fire tested,and the results show that the specific impulse varies as a quadratic function of propellant temperature.And the second generation 490N engine hot fire tests also show the same relation.This paper summarizes the results of theory and experiment research on propellant temperature effect of specific impulse.