8.4 Propulsion Subsystem Design [5–7]
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deviation and margin for propellant budget and etc. Once the propellant mass was
determined, the volume of propellant tanks and the amount of pressurized gas could
also be determined.
3. Nominal Operation Condition
Nominal operation condition for propulsion subsystem was up to the lunar lander
system and GNC subsystem in accordance with flight control requirements. The specifications of propulsion subsystem were designed on the basis of design of nominal
orbit control modes, as well as maximum output of delivery capacity, thrust drop
amplitude for orbit correction/attitude control thrusters, thrust rise amplitude for
attitude control thrusters under minimum mode of attitude control only. After the
nominal operation condition was determined, it was necessary to give input design
condition for each components and pipeline with synthetic parameter optimization
of subsystem layout, pipeline direction and length, pipeline and valve flow diameter, supply pressure of propellant tanks, pressurized gas volume, structure mass and
etc. For example, the nominal operation condition for propulsion subsystem of the
Chang’E-3 lunar lander was determined as one orbit control engine with 7500 N
thrust and six sets of attitude control thrusters with 150 N thrust.
4. Basic Configuration of Propulsion Subsystem
Basic configuration of the propulsion subsystem was up to system configuration
design of the lunar lander. Due to large-scale and heavy mass of the propulsion
subsystem, it should not only withstand its own load, but also transfer force for the
lunar lander. Therefore the propellant tanks with welded frame were used as bearing
structure of some the lunar landers. Layout and installation of large components like
tanks and orbit control engines was up to system configuration of the lunar lander, as
well as layout of pipeline, valves and especially pipeline direction. Different system
configuration led to different load bearing design and had great influence on system
structural mass. For example, the basic configuration of the Chang’E-3 lunar lander
propulsion subsystem was central cross clapboards with 4 spherical propellant tanks
symmetrically installed with their bottom fixed on the flange and the top supported
by three horizontal rods, surrounded with peripheral side plates and a 7500 N orbit
control engine located at the center of the lunar lander and 2 gas tanks hung out of
side plates.
5. Structural Mass of Propulsion Subsystem
Structural mass of the lunar lander propulsion subsystem was regarded as one of
key parameters for system design and was closely related with propellant load,
subsystem configuration, components, system configuration and etc. Generally, it
could be determined by repeating trade-off of subsystem design and system optimization of the lunar lander. Under strict constraints of structural mass, reduction of
subsystem mass could be achieved by application of new technologies, new materials, integrated and lightweight design, and subsystem optimization. For example,
the total structural mass of the Chang’E-3 lunar lander propulsion subsystem was
required to be no more than 295 kg while the propellant load was 2600 kg under
specific flight environmental conditions.
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deviation and margin for propellant budget and etc. Once the propellant mass was
determined, the volume of propellant tanks and the amount of pressurized gas could
also be determined.
3. Nominal Operation Condition
Nominal operation condition for propulsion subsystem was up to the lunar lander
system and GNC subsystem in accordance with flight control requirements. The specifications of propulsion subsystem were designed on the basis of design of nominal
orbit control modes, as well as maximum output of delivery capacity, thrust drop
amplitude for orbit correction/attitude control thrusters, thrust rise amplitude for
attitude control thrusters under minimum mode of attitude control only. After the
nominal operation condition was determined, it was necessary to give input design
condition for each components and pipeline with synthetic parameter optimization
of subsystem layout, pipeline direction and length, pipeline and valve flow diameter, supply pressure of propellant tanks, pressurized gas volume, structure mass and
etc. For example, the nominal operation condition for propulsion subsystem of the
Chang’E-3 lunar lander was determined as one orbit control engine with 7500 N
thrust and six sets of attitude control thrusters with 150 N thrust.
4. Basic Configuration of Propulsion Subsystem
Basic configuration of the propulsion subsystem was up to system configuration
design of the lunar lander. Due to large-scale and heavy mass of the propulsion
subsystem, it should not only withstand its own load, but also transfer force for the
lunar lander. Therefore the propellant tanks with welded frame were used as bearing
structure of some the lunar landers. Layout and installation of large components like
tanks and orbit control engines was up to system configuration of the lunar lander, as
well as layout of pipeline, valves and especially pipeline direction. Different system
configuration led to different load bearing design and had great influence on system
structural mass. For example, the basic configuration of the Chang’E-3 lunar lander
propulsion subsystem was central cross clapboards with 4 spherical propellant tanks
symmetrically installed with their bottom fixed on the flange and the top supported
by three horizontal rods, surrounded with peripheral side plates and a 7500 N orbit
control engine located at the center of the lunar lander and 2 gas tanks hung out of
side plates.
5. Structural Mass of Propulsion Subsystem
Structural mass of the lunar lander propulsion subsystem was regarded as one of
key parameters for system design and was closely related with propellant load,
subsystem configuration, components, system configuration and etc. Generally, it
could be determined by repeating trade-off of subsystem design and system optimization of the lunar lander. Under strict constraints of structural mass, reduction of
subsystem mass could be achieved by application of new technologies, new materials, integrated and lightweight design, and subsystem optimization. For example,
the total structural mass of the Chang’E-3 lunar lander propulsion subsystem was
required to be no more than 295 kg while the propellant load was 2600 kg under
specific flight environmental conditions.