The Apollo program made another major advance toward its goal in 1966 with three successful launches of the Saturn IB. The IB had been added to the program in 1962 as a means of conducting early manned Apollo missions in earth orbit. The IB launch vehicle was a hybrid, combining the Saturn 1's booster with the S-IVB stage that would fly as the third stage on the moon rocket. Three research and development flights were scheduled for 1966; two would check out the Apollo-Saturn IB configuration while a third tested the liquid-hydrogen propellant system in the S-IVB stage. A fourth Saturn IB launch, scheduled toward the end of 1966, would put the first Apollo crew into space. The launches posed a challenge for KSC. In the midst of a major site activation - LC-39 - the launch team faced a new operation. There was a new launch vehicle stage and, with the RCA 110A computers, a new checkout system. Before completing the missions, the launch team would experience some of the most frustrating moments in the entire Apollo program.
First sign of the Saturn IB series at the Cape was NASA's rebuilding of the LC-34 facilities. The complex had last been used to launch SA-4 in March 1963. During the rest of the year, LC-34 was earmarked for back-up service during the Saturn I, block II series. Contractors had completed a gas storage building and begun work on liquid-hydrogen facilities. Mueller's revised launch schedule of 1 November 1963 had prompted Debus to recommend cancellation of further Saturn I work at the complex. NASA then began the task of readying LC-34 for the launching of AS-201, first of the Saturn IBs.1
The old LC-34 service structure was almost completely rebuilt. Previously open to the winds, it was now equipped with hurricane gates and four weather-tight silo enclosures. Anchor piers were strengthened to hold the service structure in place over the pad. The modifications also included eight vertically adjustable service platforms and new traveling hoist machinery. On the umbilical tower, the swing arms were rebuilt to meet the new rocket's dimensions; testing was completed in June 1965. Astronauts would board the command module through a new arm at the 67-meter level. The addition included a white room to control the temperature and cleanliness inside the module. While AS-201 would be an unmanned flight, the launch complex would be man-rated in almost every particular.2
The change from the Saturn I to the IB meant larger fuel requirements, for the upper stage a 130% increase. Major alterations were made in LC-34's propellant facilities. The RP-1 main storage tanks were reinsulated and the liquid-hydrogen system was enlarged. A new tanking control system loaded propellants to prescribed levels and maintained those levels until liftoff. Pneumatic requirements involved modification of the high-pressure gaseous nitrogen and helium installations and construction of a gaseous hydrogen system.3
Colonel Bagnulo reported on 5 August 1965 that, "after a full measure of blood, sweat, and tears," the basic modifications to the service structure were essentially complete. The initial contract cost had risen from $3.5 million to $5.3 million, partly because of changes to the design, but more from the additional overtime required to keep the work near the original schedule. Minor work continued almost up to launch time; the last change requirements were released on 4 January 1966.4