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Jul 14, 2012

Lunar Module Control Subsystems (Part 8, Apollo Control Systems)

Lunar Module control system was divide to 12 subsystems. We have already described some of them in our previous parts. Here is now a simplified picture of the LM complete control system and its subsystems.

LM Control System. Many LM subsystems were heavily connected to each other. For example the Instrumentation (IS) collected data from all subsystems. This is sown as C.M.S. (connected to many subsystems).

Since LM was among the first computer controlled vehicles all functions could also be carried manually. This was possible by connecting all systems to "Controls and Displays" (CDS, on the left of the diagram) which was actually all the LM cockpit panels together. The LM was filled with control and display panels.

"Guidance, Navigation, and Control" was the other central part of the system and it consisted of 2 computers and control electronics (CES). The primary computer ("Primary Guidance and Navigation Section", PGNS) was made by MIT and the secondary (called "Abort Guidance Section (or System)", AGS) by TRW. The whole LM was mostly built by Grumman. First steering tests were carried out with the CES and later it got more and more automated with those computers. Earlier manual modes and capabilities were kept in the system for redundancy and safety. That is the reason why hand controllers (TTCA's and ACA's) were connected to CES, PGNS and AGS and the actual control path was chosen by switches and flight modes.

Radar was its own subsystem with two different types of radars (Landing Radar, LR and Rendezvous Radar, RR). The other vital sensors were the Inertial Measurement Unit (IMU) and PIPA (Pulsed Integrating Pendulous Accelerometer)  in the ISS (Inertial Subsection) of the PGNS and Alingment Optical Telescope (AOT) in the OSS (Optical Subsection) shown also on the above diagram. Here are all the subsystems listed.

LM Subsystems:

  1. Controls and Displays (CDS)
  2. Guidance, Navigation, and Control (GN&CS)
  3. Main Propulsion (MPS)
  4. Reaction Control (RCS)
  5. Instrumentation (IS)
  6. Communication CS)
  7. Crew Personal Equipment (CPES)
  8. Electrical Power (EPS)
  9. Radar (RS)
  10. Explosive Devices (EDS)
  11. Environmental Control (ECS)
  12. Lighting (LS)

We have already handled 2 subsystems (the RCS and EDS) and partially the ECS, its HTS (Heat Transport Section). We will continue to describe those in more detail in the following parts of this series and finally also cover the Command Service Module (CSM) and the Launch Vehicle (LV), Saturn V.


/1/ Grumman - LMA790-2 - Lunar Module Vehicle Familiarization Manual - LM 10-14 - 1969
/2/ Grumman - LMA790-3 - Lunar Module Subsystems Data - LM10 - 1971
/3/ Grumman - COURSE NO. 30005-012 - LM Orientation - 1966
/4/ Grumman - LMA790-1 - Lunar Excursion Module Familiarization Manual  - 1965

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