Sukhoi T-3 and missile sub-systems, two of the prototypes were converted to become the PT-7 and PT-8. The PT-7 had a variable intake ramp, while the PT-8 had an extended nose with a translating centerbody. Although not proceeded with, the T-3 served as the basis for what would eventually become the Sukhoi Su-9, forming the backbone of the PVO during the 1960s. Sukhoi T-3 The Sukhoi T-3 was a prototype Soviet fighter aircraft. Starting in the early 1950s, the development of the T-3 proceeded in parallel with the S-1 which would eventually become the Sukhoi Su-7. While the S-1 was a conventional
Sukhoi Su-15 the Su-15 was abruptly retired from the new Russian Air Force in 1993 to comply with the Treaty on Conventional Armed Forces in Europe. Most were hastily scrapped in favour of more advanced interceptors, including the Su-27 and MiG-31, but some are in reserve storage for emergency use. In Ukraine, the last Su-15s (at Kramatorsk and Belbek) were withdrawn from use in 1996. Some Western reports indicate that the Su-15TM was also designated Su-21 and the Su-15UM Su-21U. These reports are apparently incorrect. Designation Su-21 was reserved for Su-17M4 but never used. Sukhoi Su-15 The Sukhoi Su-15 (NATO reporting name: