In the initial stage of Cold War, bombers were expected to attack flying higher and faster, even at transonic speeds. Initial transonic and supersonic fighters had modest internal fuel tanks in their slim fuselages, but a very high fuel consumption. This led fighter prototypes emphasizing acceleration and operational ceiling, with a sacrifice on the loiter time, essentially limiting them to point defense role. Such were the mixed jet/rocket power Republic XF-91 or Saunders Roe SR.53. The Soviet and Western trials with zero-length launch were also related. None of these found practical use. Designs that depended solely on jet engines achieved more success with the F-104 Starfighter (initial A version) and the English Electric Lightning.