Area navigation on the L-1011 was accomplished by the use of an Inertial Navigation System. Some L-1011s also used the now dismantled OMEGA system for area navigation. OMEGA was more or less the first global position indication system that used a network of terrestrial antennas to create signals that could be triangulated into a position with roughly 8 NM accuracy. OMEGA was replaced by the public version of GPS around 1996.
Over the next few weeks I will be creating a simulation of the Litton LTN-72RL INS. The LTN-72RL CDU basically acts as a terminal for the INS unit and in a triple system installation, as in the image above, all 3 INS units can be synchronized with each other. Here is the test setup on the workbench:
Inertial Navigation Systems (INS) are still very much in use today. I will not go too much into detail on how INS technology works, but trust me, it is super cool. Read about it on Wikipedia by following the link. Present day Inertial Reference Units (IRUs) use lasers and are ultra precise. One of the main manufactures of INS and OMEGA systems was Litton Aero Products which got acquired by Northrop Grumman in 2001.
The image below, taken from airliners.net, shows three Litton CDUs installed in the RAF L-1011 tanker.
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| from. airliners.net (C) Duncan Monk |
Over the next few weeks I will be creating a simulation of the Litton LTN-72RL INS. The LTN-72RL CDU basically acts as a terminal for the INS unit and in a triple system installation, as in the image above, all 3 INS units can be synchronized with each other. Here is the test setup on the workbench:
Litton LTN-72RL CDU and INS MODE SELECTOR on DZUS Rails
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Litton LTN-72RL CDU and INS MODE SELECTOR on DZUS Rails
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Litton LTN-72RL CDU and INS MODE SELECTOR on DZUS Rails
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Litton LTN-72RL CDU and INS MODE SELECTOR on DZUS Rails
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For this series of avionics bending I will be using the ARINC 575 protocol format. ARINC 575 is electrically identical to ARINC 429 however the general word format is different. ARINC 575, just like ARINC 429, uses an 8bit label and a 24bit data filed. However, unlike ARINC 429 the 575 format does not compute parity, does not have a SID or a defined SSM filed. The Litton CDU uses ARINC 575 words for data between the CDU and the INS unit in both directions. In the next posting we will take a look at the general system architecture and how I will go about creating and INS system and then integrating it with x-plane.
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