Based on the full flow staged combustion (FFSC) cycle engine balance model

three parameters were selected for the engine system design

such as hydrogen transpiration cooling mass flow rate

combustion chamber pressure and combustion chamber mixture ratio.These results show that

when the thrust and nozzle expansion ratio are kept constant:(1) with the increase of hydrogen transpiration cooling mass flow rate

the fuel pump lift ascends rapidly and the oxidizer pump lift falls down;(2) with the increase of combusion chamber pressure

the pump lift ascends linearly before combustion chamber pressure at 20MPa and rapidly after 20MPa

so 20MPa is recommended for combustion chamber pressure;(3) with the increase of combustion chamber mixture ratio

the fuel pump lift ascends linearly

the oxidizer pump lift reduces rapidly and then slowly

so seven is recommended for combustion chamber mixture ratio.The effects of these design parameters on engine system parameters offer a reasonable range for engine system design.