Apollo Lunar Module Thrust Meter Restored to Functionality

Apollo Lunar Module Thrust Meter Receives a New Life

[Mike Stewart] has successfully revived a thrust measurement system from an Apollo lunar module. This device passed inspection on September 25, 1969. Fortunately, [Mike] discovered some old documentation that included the necessary pin numbers, which was a significant victory!

It's fascinating to see the various revisions this humble measuring device has undergone. Some of the most recent improvements were made to address an issue related to the absence of an indication in case of a malfunction, leading to the inclusion of a relay that can activate a warning light if the device loses power.

This examination of the lunar thrust module clearly illustrates how the complexity of a system can quickly spiral out of control. Instead of having a single pin, there are now two pins to indicate automatic or manual thrust, each operating at different voltage levels. The manual thrust is precisely specified, but the automatic thrust represents only a portion of the thrust added to a base thrust, meaning they must be managed differently, necessitating additional logic and wiring to properly adjust the thrust meter when needed.

At the end of the video, [Mike] shows us how the lights behind the device look when powered. If you're interested in the technology behind the Apollo missions, don't miss Don Eyles' presentation on the source code of the lunar module.