What is the JT3D engine used for?
The JT3D made its first flight on a Boeing 707-120 on June 22, 1960, and powered the Boeing 707-120B, Boeing 720, and Douglas DC-8-50 airliners. Although initially funded by the U. S. Air Force as the T33, the JT3D is an historic commercial jet transport engine. The prototype Boeing 707 (367-80), now in the collection of the National Air and Space Museum, was powered by the JT3 engine. When modified to the JT3D turbofan configuration, this engine powered the same transports with greater fuel efficiency, more thrust, and less noise.