Versions
The CM and LM used the same computer, inertial platform and resolvers. The main difference was the optical unit. The Navbase was different for each spacecraft as well, reflecting the differing mounting geometries. The LM's rendezvous radar was also connected to its Navbase.
There were two versions of PGNCS—Block I and Block II—corresponding to the two generations of the CM. After the Apollo I fire, which occurred in a Block I CM, NASA decided that no further manned missions would use Block I, though unmanned missions did. Major differences between Block I and Block II PGNCS included replacing electromechanical resolvers with an all electronic design and replacing the Block I Navbase, which was machined from beryllium, with a frame built out of aluminum tubing filled with polyurethane foam. The Block II Navbases were lighter, cheaper and just as rigid.
Components from PGNCS were used by Draper for the U.S. Navy's Deep Submergence Rescue Vehicle (DSRV).
Read more about this topic: Apollo PGNCS
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“The assumption must be that those who can see value only in tradition, or versions of it, deny man’s ability to adapt to changing circumstances.”
—Stephen Bayley (b. 1951)