While flight-preparation crews were having problems, Grissom, White, and Chaffee were finding bottlenecks in training activities. The chief problem was keeping the Apollo mission simulator current with changes being made in spacecraft 012.
Apollo Saturn 201 employed the Saturn IB launch vehicle, which was the up-rated version of the Saturn I rocket flown in ten earlier Saturn-Apollo missions. It featured an upgrade of the first stage engines to increase thrust from 1,500,000 lb-ft of thrust to 1,600,000 lb-ft. The second stage was the S-IVB. This stage used a new liquid hydrogen-burning J-2 engine which would also be used on the S-II second stage of the Saturn V lunar launch vehicle…
“Some of those guys came in figuring, “I’ll write my textbooks and my thesis and teach [university courses] and I’ll come by twice a week and be an astronaut.” Well, that didn’t work …. We were devoting our lives to this whole thing, and you couldn’t devote anything less, I don’t care what your discipline was.”
With Group 4, for the first time, the selection criteria did not include a requirement for test pilot proficiency. Selectees who were not qualified pilots would be assigned to the Air Force for a year of flight training. The primary scientific requirement was a doctorate in medicine, engineering, or one of the natural sciences.