Saturn V Instrument Unit
The Saturn V Instrument Unit is a ring-shaped structure fitted to the top of the Saturn V rocket's third stage (S-IVB) and the Saturn IB's second stage (also an S-IVB). It was immediately below the SLA (Spacecraft/Lunar Module Adapter) panels that contained the Lunar Module. The Instrument Unit contains the guidance system for the Saturn V rocket. Some of the electronics contained within the Instrument Unit are a digital computer, analog flight control computer, emergency detection system, inertial guidance platform, control accelerometers and control rate gyros. The instrument unit (IU) for Saturn V was designed by NASA at Marshall Space Flight Center (MSFC) and was developed from the Saturn I IU. NASA's contractor to construct the Saturn V Instrument Unit was International Business Machines (IBM).One of the unused Instrument Units is currently on display at the Steven F. Udvar-Hazy Center in Chantilly, Virginia. The plaque for the Unit has the following inscription:The Saturn V rocket, which sent astronauts to the Moon, used inertial guidance, a self-contained system that guided the rocket's trajectory. The rocket booster had a guidance system separate from those on the command and lunar modules. It was contained in an instrument unit like this one, a ring located between the rocket's third stage and the command and lunar modules. The ring contained the basic guidance system components—a stable platform, accelerometers, a digital computer, and control electronics—as well as radar, telemetry, and other units.The instrument unit's stable platform was based on an experimental unit for the German V-2 rocket of World War II. The Bendix Corporation produced the platform, while IBM designed and built the unit's digital computer.