J57 turbojet engine?

Question

For a J57-P-23 engine, what does the number 57 and 23 designate or represent?

Answer 1

The 57 is a model number and the 23 is a revision number, you could call it a Type 57 Mark 23. Other J57 will be the same size but the parts and specifications may be significantly different.

J57s ranged from around 9000 to 18000 lbs thrust, the 23 is 17,200 so it's one of the better ones. They were in production from 51 to 70 and used on things as diverse and Sky Warriors, KC135s, Super Sabers, Voodoos and the U2!

See the P&W J57 page, below

Answer 2

The Pratt & Whitney JT3C (USAF designation: J57) was a development of the T45 turboprop engine intended for the XB-52. As the B-52 power requirements grew, the design evolved into a turbojet. The JT3C was the first 10,000 lbf (45 kN) thrust class engine in the United States.

The prestigious Collier Trophy for 1952 was awarded to Leonard S. Hobbs, Chief Engineer of United Aircraft Corp., for "designing and producing the P&W J57 turbojet engine".

On May 25, 1953, a J57-powered YF-100A exceeded Mach 1 on its maiden flight. The engine was produced from 1951 to 1965 with a total of 21,170 built. The JT3C was developed into Pratt & Whitney JT3D turbofan.
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http://en.wikipedia.org/wiki/J-57
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