The stage provided 34,500 kN (7,750,000 lbf)[2] of thrust at sea level to get the rocket through the first 61 km (38 mi) of ascent.

By this time the general design of the stage had been decided on by the engineers at the Marshall Space Flight Center (MSFC).

Wind tunnel testing took place in Seattle and the machining of the tools needed to build the stages at Wichita, Kansas.

MSFC built the first three test stages (S-IC-T, the S-IC-S, and the S-IC-F) and the first two flight models (S-IC-1 and -2).

[5] In July 1967, NASA awarded Boeing a contract to begin long-lead-time item acquisition (such as propellant lines and tank components) for the 16th and 17th S-IC stages.

A full contract for the construction of S-IC-16 to S-IC-25 was drafted throughout mid-1967, but stages past S-IC-15 were canceled altogether in October of that year due to budgetary restrictions.

The largest and heaviest single component of the S-IC was the thrust structure, with a mass of 24 short tons (48,000 lb; 22,000 kg).

These were among the largest aluminum forgings produced in the U.S. at the time, 4.6 m (15 ft) long and 820 kg (1,800 lb) in weight.

Both the thrust structure and fuel tank had alternating black and white paint, in order to monitor the vehicle's roll during flight.