15.8 Joint Firing Test of Throttling Engine and GNC CCU
511
15.8.2 Test Constraints and Methodology
When the test system for joint firing test of throttling engine and CCU was designed,
the following constraints should be considered.
(1) It could simulate the vacuum environment while the engine was firing on orbit.
(2) It could measure the actual thrust of the throttling engine.
(3) It could simulate the throttling control system.
(4) It could cover the firing condition of the throttling engine on orbit.
In order to satisfy above constraints, vacuum test chamber and engine testbed was
necessary to simulate the vacuum environment. Real engine should be applied to
simulate the thrust characteristics in the test. Real CCU and throttling control system
should also be applied in the test.
When the test conditions were determined, all conditions on orbit should be
comprehensively regarded. In all flight phases of the lunar lander, the throttling
engine should be fired for many times. The first one was for TCM in LTO, then LOI,
orbit change on circumlunar orbit, and powered descent at last. In all of this, the
throttling condition during powered descent was the most complicated process, with
high-frequency throttling, large throttling range and high-demand for thrust throttling response. At the same time, the response of propulsion subsystem to throttling
command of GNC subsystem should be quickly and performed correctly. Therefore,
the test for powered descent was generally selected for examination.
15.8.3 Design of Test System
The test system for joint firing test of throttling engine and CCU was composed
of throttling engine, throttling control subsystem, vacuum simulation subsystem,
parameter measurement subsystem, test control subsystem and engine testbed
pipeline, as shown in Fig. 15.17.
1. 7500 N Throttling Engine
As controlled target of the test system, in order to simulate output load characteristics
of the throttling engine, real engine should be applied in the test.
2. Throttling Control Subsystem
The throttling control subsystem was applied to control the thrust of throttling engine
in the test. The throttling control subsystem was composed of real controller, ground
test equipment and test cables.
3. Vacuum Simulation Subsystem
The vacuum simulation subsystem was applied to simulate vacuum environment in
the test, which consisted of vacuum tank, pre-evacuation system, ejection pipeline
and ejection system.
511
15.8.2 Test Constraints and Methodology
When the test system for joint firing test of throttling engine and CCU was designed,
the following constraints should be considered.
(1) It could simulate the vacuum environment while the engine was firing on orbit.
(2) It could measure the actual thrust of the throttling engine.
(3) It could simulate the throttling control system.
(4) It could cover the firing condition of the throttling engine on orbit.
In order to satisfy above constraints, vacuum test chamber and engine testbed was
necessary to simulate the vacuum environment. Real engine should be applied to
simulate the thrust characteristics in the test. Real CCU and throttling control system
should also be applied in the test.
When the test conditions were determined, all conditions on orbit should be
comprehensively regarded. In all flight phases of the lunar lander, the throttling
engine should be fired for many times. The first one was for TCM in LTO, then LOI,
orbit change on circumlunar orbit, and powered descent at last. In all of this, the
throttling condition during powered descent was the most complicated process, with
high-frequency throttling, large throttling range and high-demand for thrust throttling response. At the same time, the response of propulsion subsystem to throttling
command of GNC subsystem should be quickly and performed correctly. Therefore,
the test for powered descent was generally selected for examination.
15.8.3 Design of Test System
The test system for joint firing test of throttling engine and CCU was composed
of throttling engine, throttling control subsystem, vacuum simulation subsystem,
parameter measurement subsystem, test control subsystem and engine testbed
pipeline, as shown in Fig. 15.17.
1. 7500 N Throttling Engine
As controlled target of the test system, in order to simulate output load characteristics
of the throttling engine, real engine should be applied in the test.
2. Throttling Control Subsystem
The throttling control subsystem was applied to control the thrust of throttling engine
in the test. The throttling control subsystem was composed of real controller, ground
test equipment and test cables.
3. Vacuum Simulation Subsystem
The vacuum simulation subsystem was applied to simulate vacuum environment in
the test, which consisted of vacuum tank, pre-evacuation system, ejection pipeline
and ejection system.