The surrender of Germany, in 1945, unlocked a treasure trove of wartime discoveries and inventions. General Electric and Pratt & Whitney, another American engine-builder, added German lessons to those of Whittle and other British designers. Early jet engines, such as those of the Me 262, gulped fuel rapidly. Thus, an initial challengeinvolved building an engine that could give high thrust with less fuel consumption.
http://www.pilotfriend.com/aero_engines/images3/4.jpg" height="273" border="0" width="431" alt="" />
The J-31 (also known by its company designation, I-16) was the first turbojet engine produced in quantity in the United States. It was developed from the original American-built jet engine, the General Electric I-A, which was a copy of the highly secret British "Whittle" engine.
Pratt & Whitney solved this problem in 1948 with its "dual spool" concept. This combined two engines into one. The engine had two compressors—each rotated independently, with the inner one giving high compression for good performance. Each compressor drew power from its own turbine; hence there were two turbines, one behind the other.
This approach led to the J-57 engine
, which entered service with the U.S. Air Force in 1953.
� 1998 -