And the Saturn V only had enough lifting capacity because the Air Force had issued a requirement to Rocketdyne back in 1955 for an engine powerful enough to deliver the huge H-bombs in use at the time. Within a few years, nuclear weapons researchers had figured out how to build lighter weapons so the huge F-1 engine was no longer needed for ICBMs, but fortunately it was ready for use in the Apollo program. The USSR had nothing comparable.