Lyulka AL-21

The Lyulka AL-21 is an axial flow turbojet engine created by the Soviet Design Bureau named for its chief designer Arkhip Lyulka.

Design and development
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).