 The Titan II launch vehicle used for the Gemini program had been notoriously rough @-@ riding , and technicians promised the astronauts that the Saturn V , which was designed for the Apollo program rather than adapted from a missile , would have a much smoother ride . Lovell and Borman , both Gemini veterans , found this promise did not disappoint . During liftoff , they reported feeling nothing but a dull , muted rumble in the distance . 
