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8 Propulsion Technology of Lunar Lander
The flight hardware of propulsion subsystem should be tested and verified to check
function, performance, environmental adaptability and interface correctness. There
should be tests in component, modular, subsystem and system level. The test items
included electric performance, parameters adjusting, leakage rate, accuracy, polarity,
engine/thruster simulated hot firing test for high altitude, hot firing of propulsion
subsystem, tank expulsion, gas tank burst and environmental test and etc. The tests
for propulsion subsystem of the Chang’E-3 lunar lander are given in Table 8.5.
2. Propellant Filling
Propellant filling was one of key operation for propulsion subsystem in launch site.
Because of properties such as high toxicity, strong corrosion, flammable and explosive and etc., reliable and safe requirements for propellant filling were very high.
At the same time, the operation was irreversible once propellant is filled, so it was
highly emphasized. Propellant and gas filling are both implemented by ground equipment. According to different tank type, rational option for concrete filling method
would be made. For example, propellant filling with tank evacuation was chosen for
propulsion subsystem of the Chang’E-3 lunar lander because metal diaphragm tank
was applied. Before filling, the internal cavity was evacuated. After required vacuum
degree (generally vacuum pressure below 133 Pa) was satisfied, the propellant was
pressurized and filled into tank while the propellant load was weighted. In particular,
in the process of propellant filling, MON-1 oxidizer should be cooled for strictly
maintaining the pressure in the liquid cavity of the tank to be less than restricted
reverse pressure on metal diaphragm.
8.5 Testing and Verification of Propulsion Subsystem
The components of the propulsion subsystem were usually types of mechanic,
electro-mechanic or electronic products with the feature of pressure bearing, load
bearing, movement, fluid, combustion, thermal control and etc. System composition
was complex. The products were closely related to manufacture process and materials used. Furthermore, a lot of working processes were difficult to be accurately
analyzed by means of theoretical simulation. And past experience and experimentation were important basis of design. For example, engine combustion performance
was basically verified by a great many tests. So a great many ground tests in component, subsystem and system level should be conducted for propulsion subsystem
of the lunar lander. Tests were generally classified into acceptance, qualification,
batch sampling and marginal test. Tests covered electric performance, parameter
adjusting, leak test, accuracy measuring, environmental tests (centrifugal, vibration,
shock, high and low temperature, moisture and hot, thermal vacuum, thermal circle
and stress test), actuation characteristics, engine/thruster hot firing, pressure fatigue
circle, burst strength, subsystem integration test, EMC and etc. Qualification test was
applied for comprehensive validation of product function, performance, reliability,
environmental adaptability, quality and etc. According to different types of products,
8 Propulsion Technology of Lunar Lander
The flight hardware of propulsion subsystem should be tested and verified to check
function, performance, environmental adaptability and interface correctness. There
should be tests in component, modular, subsystem and system level. The test items
included electric performance, parameters adjusting, leakage rate, accuracy, polarity,
engine/thruster simulated hot firing test for high altitude, hot firing of propulsion
subsystem, tank expulsion, gas tank burst and environmental test and etc. The tests
for propulsion subsystem of the Chang’E-3 lunar lander are given in Table 8.5.
2. Propellant Filling
Propellant filling was one of key operation for propulsion subsystem in launch site.
Because of properties such as high toxicity, strong corrosion, flammable and explosive and etc., reliable and safe requirements for propellant filling were very high.
At the same time, the operation was irreversible once propellant is filled, so it was
highly emphasized. Propellant and gas filling are both implemented by ground equipment. According to different tank type, rational option for concrete filling method
would be made. For example, propellant filling with tank evacuation was chosen for
propulsion subsystem of the Chang’E-3 lunar lander because metal diaphragm tank
was applied. Before filling, the internal cavity was evacuated. After required vacuum
degree (generally vacuum pressure below 133 Pa) was satisfied, the propellant was
pressurized and filled into tank while the propellant load was weighted. In particular,
in the process of propellant filling, MON-1 oxidizer should be cooled for strictly
maintaining the pressure in the liquid cavity of the tank to be less than restricted
reverse pressure on metal diaphragm.
8.5 Testing and Verification of Propulsion Subsystem
The components of the propulsion subsystem were usually types of mechanic,
electro-mechanic or electronic products with the feature of pressure bearing, load
bearing, movement, fluid, combustion, thermal control and etc. System composition
was complex. The products were closely related to manufacture process and materials used. Furthermore, a lot of working processes were difficult to be accurately
analyzed by means of theoretical simulation. And past experience and experimentation were important basis of design. For example, engine combustion performance
was basically verified by a great many tests. So a great many ground tests in component, subsystem and system level should be conducted for propulsion subsystem
of the lunar lander. Tests were generally classified into acceptance, qualification,
batch sampling and marginal test. Tests covered electric performance, parameter
adjusting, leak test, accuracy measuring, environmental tests (centrifugal, vibration,
shock, high and low temperature, moisture and hot, thermal vacuum, thermal circle
and stress test), actuation characteristics, engine/thruster hot firing, pressure fatigue
circle, burst strength, subsystem integration test, EMC and etc. Qualification test was
applied for comprehensive validation of product function, performance, reliability,
environmental adaptability, quality and etc. According to different types of products,