298
8 Propulsion Technology of Lunar Lander
was deviated to 1.85 in 9000 N thrust output. The test fully evaluated the operation
margin of the engine.
2. Hot Firing with Wet Stored Propellant
Hot firing with wet stored propellant could simulate the engine restart performance
and reliability after long term contact with propellant during flight, especially smoothness of moving parts. Several sets of engines conducted multiple fire tests when the
engine was developed, including short nozzle engines after 30 days, 64 days propellant wetted storage restated and large nozzle engines after 19 days propellant wetted
storage restated. The engines all worked normally, reliably and stably. The thrust
could be modulated flexibly and operated with good performance consistency.
3. Hot Firing after Engine Neutralization
Hot firing after engine neutralization was conducted to verify the performance and
reliability of engine after its firing and subsequent neutralization of disassembling,
cleaning, drying, adjusting and reassembling. There were 3 sets of short nozzle and
4 sets of large nozzle conducted hot firing after neutralization. The flight hardware of
throttling engine after neutralization was reassembled and installed on the Chang’E3 lunar lander, which was successful in flight mission. Ground and flight test results
showed that the engine after neutralization worked reliably and stably.
4. Hot Firing under High and Low Temperature
Hot firing under high and low temperature was conducted to verify the engine adaptability to environmental temperature change. Multiple fire tests were conducted under
different propellant temperature of −1~33 °C with normal, stable and consistent
operation.
5. Hot Firing with Heat Shield
In order to verify the performance and reliability of the engine with heat shield, hot
firing of 2 sets of large nozzle engines was conducted with accumulated firing time
more than 4000 s for each set and continuous firing 2000 s once. The duration with
nominal 7500 N output was 1000 s with maximal temperature of 1280 °C at throat.
Test results showed that the engine with heat shield had suitable temperature and
worked reliably.
8.5.3 Propellant Tank Test
The characteristics of propellant tank for propulsion subsystem of the lunar lander
was large propellant load, high expulsion efficiency, small structural mass, special
installation configuration, harsh vibration condition, wide flow variation, high consistency of pressure drop in parallel tank and etc. Furthermore, it should endure zerogravity and lateral overload condition for propellant discharge in soft-landing. So
it was very difficult for design of propellant management, shell pressure-bearing
8 Propulsion Technology of Lunar Lander
was deviated to 1.85 in 9000 N thrust output. The test fully evaluated the operation
margin of the engine.
2. Hot Firing with Wet Stored Propellant
Hot firing with wet stored propellant could simulate the engine restart performance
and reliability after long term contact with propellant during flight, especially smoothness of moving parts. Several sets of engines conducted multiple fire tests when the
engine was developed, including short nozzle engines after 30 days, 64 days propellant wetted storage restated and large nozzle engines after 19 days propellant wetted
storage restated. The engines all worked normally, reliably and stably. The thrust
could be modulated flexibly and operated with good performance consistency.
3. Hot Firing after Engine Neutralization
Hot firing after engine neutralization was conducted to verify the performance and
reliability of engine after its firing and subsequent neutralization of disassembling,
cleaning, drying, adjusting and reassembling. There were 3 sets of short nozzle and
4 sets of large nozzle conducted hot firing after neutralization. The flight hardware of
throttling engine after neutralization was reassembled and installed on the Chang’E3 lunar lander, which was successful in flight mission. Ground and flight test results
showed that the engine after neutralization worked reliably and stably.
4. Hot Firing under High and Low Temperature
Hot firing under high and low temperature was conducted to verify the engine adaptability to environmental temperature change. Multiple fire tests were conducted under
different propellant temperature of −1~33 °C with normal, stable and consistent
operation.
5. Hot Firing with Heat Shield
In order to verify the performance and reliability of the engine with heat shield, hot
firing of 2 sets of large nozzle engines was conducted with accumulated firing time
more than 4000 s for each set and continuous firing 2000 s once. The duration with
nominal 7500 N output was 1000 s with maximal temperature of 1280 °C at throat.
Test results showed that the engine with heat shield had suitable temperature and
worked reliably.
8.5.3 Propellant Tank Test
The characteristics of propellant tank for propulsion subsystem of the lunar lander
was large propellant load, high expulsion efficiency, small structural mass, special
installation configuration, harsh vibration condition, wide flow variation, high consistency of pressure drop in parallel tank and etc. Furthermore, it should endure zerogravity and lateral overload condition for propellant discharge in soft-landing. So
it was very difficult for design of propellant management, shell pressure-bearing