Saturn V Instrument Unit Gallery

These images show the development of the IU. The first four Saturn launches did not have an IU, but used guidance, telemetry and other equipment installed on top of the first stage.

The first IU flew on the fifth Saturn launch, SA-5, and was 12 feet 10 inches (3.9 m) in diameter and 4 feet 10 inches (1.5 m) high. The components it carried were in pressurized containers. This version flew on SA-5, SA-6 and SA-7. The IU carried by missions SA-8, -9, and -10 was only 2 feet 10 inches (0.86 m) high, and was not pressurized.

With the Saturn IB and Saturn V launches, a third version was used, 21.6 feet (6.6 m) in diameter and 3 feet (0.91 m) high. Comparison of these photographs of the Instrument Unit shows that the configuration of components carried by this version changed, depending on the mission. Some equipment was deleted (e.g. the Azusa tracking system was deleted from later IUs), some equipment was added (e.g. a fourth battery for longer missions), and other components were moved around.

These images also show that some components (e.g. batteries, the ST-124 inertial platform) were installed in the IU after it had been stacked in the VAB on top of the S-IVB third stage.