While Pratt & Whitney certainly competed for the engine to power this transport, it never seemed to take the high bypass engine requirement seriously as evinced by its first demonstrator's bypass ratio being little more than that of the then-flying JT3D.
From this review came a requirement for "a large military transport with high bypass engines." It was unusual, even irregular, to have a system requirement and a subsystem solution--the high bypass engine--both specified as a requirement.
Historically, the two leading domestic commercial airplane builders, Boeing with its 7J7 and McDonnell Douglas Corp., were planning to introduce propfan engines, also known as ultra-high bypass engines
, on new jetliners.
Ultrahigh bypass engines that offer the benefits of lower noise and lower fuel consumption also present a difficult challenge to the aircraft designer.
Modern, highly reliable gear systems will become a proven component of ultrahigh bypass engines in the future.