The AL-21 is closely similar in technology to the
General Electric J79 first flown in 1955, which was the first engine for supersonic flight, using a variable stator. It is generally described as being in the "third generation" of Soviet
gas turbine engines which are characterized by high thrust-to-weight ratios and the use of
turbine air cooling. The AL-21 entered service in the early 1960s. Later designed the
AL-21F3, it was used in the
Sukhoi Su-17,
Sukhoi Su-24, Ground-attack variant
Mikoyan-Gurevich MiG-23, and
Sukhoi T-10 (
Sukhoi Su-27 prototype). ==Specifications (AL-21F3)==