Like the United States and Britain in the post-World War 2 years, the Soviet Union managed a long history in perfecting turbojet-powered combat aircraft. There were many failures for each singular success and these ran the gamut of fighters, bombers, specialized attack platforms, and interceptors. In the latter, the Sukhoi Su-15 (NATO codename of "Flagon") proved a successful entry. Production totaled 1,290 units with the last operational forms remaining active until 1996 with the Ukrainian Air Force (its only foreign operator).
The primary conventional threat to Soviet air defense of the 1950s became the Boeing B-52 "Stratofortress" - a mammoth jet-powered heavy bomber introduced in early 1955 with the USAF. Flying high and carrying a great warload of bombs, the aircraft proved herself a capable platform and manufacture ultimately netted 744 of the type (the design remains active even today - 2016). At this point in Soviet aviation history, the primary interceptors on hand were the Sukhoi Su-9 and Su-11 which, it was realized by Soviet authorities, did not hold the intercepting capabilities required of them to counter the B-52 threat and others emerging from the United States and Britain.
From the Sukhoi "T-49" prototype arose the" T-58" which relied on an ultra-streamlined form that included swept-back wings and a side-by-side twin-engine configuration. The pilot sat aft of a radar-equipped nosecone with generally good views of the area surrounding his airplane. The twin engines were aspirated by side-mounted intakes and exhausted at the tail through circular ports. The wing mainplanes were set about midships and low-mounted along the fuselage sides.
The prototype achieved first-flight on May 30th, 1962 and this form, following some alterations to make her service-capable, was selected for serial production in February of 1962 carrying the designation of "Su-15". From August 1963 on it was involved in the usual service tests required of Soviet aircraft but the expected production lines Novosibirsk (already committed to the Yakovlev Yak-25) were contested and served to delay entry of the Su-15. As such, its introduction did not take place until 1965 and, once recognized by NATO, it received the codename of "Flagon-A".
A "one-off" prototype followed as the "T-58VD" ("Flagon-B") that utilized three lift-jets along its center mass in an attempt to provide an inherent Short Take-Off and Landing (STOL) capability to the series but this complex variant was not adopted. The next major variant arrived in the "Flagon-D" of 1970 which included extended wingtip structures. The Su-15UT ("Flagon-C") was a dedicated two-seat trainer lacking radar and combat capability and this model arrived in 1970. The Su-15T ("Flagon-E") carried Volkov "Taifun" radar and the Su-15TM ("Flagon-F") of 1971 became an improvement of the same form with Taifun-M series radar and refined aerodynamics including a new nose section. In 1976, the Su-15UM ("Flagon-G") was brought online as a dedicated trainer form for the Su-15TM combat model.
Beyond these, there were also a range of unbuilt Su-15 types including the "U-58UM" based on the Su-15UM with Taifun-M radar, the "Su-15Sh" intended as a supersonic-capable ground attack aircraft, and the "Su-15-30" slated to carry the radar suite and missile armament of the Mikoyan-Gurevich MiG-25 "Foxbat" interceptor. None were adopted for serial production.
The Su-15bis was an Su-15TM given R-25-300 series engines of 15,652lb thrust with afterburning capability. While officially accepted by the Soviet Air Force, the lack of engines doomed its progress. The Su-19 (based on the prototype T-58PS) was a another proposed model intended to carry the R-25-300 series engines and a new ogival wing set but never materialized.
Once in service, the Su-15 became an important functional component of the Soviet defense of its vast airspace and was slated to work in conjunction with the faster Mig-25 series as a potent "one-two" punch against an enemy bomber. As it stood, the Su-15 was a fast, high-flying aircraft for its time with an excellent climb rate capable of quick response times against incoming enemy threats: its potent radar fit directed the aircraft to the target by way of datalink with ground control centers and missiles would engage the target once in range. Early Su-15s carried two air-to-air missiles (AAMs) in either an Infrared Homing (IR) or Semi-Active Radar (SAR) Homing flavor while later Su-15s were given four hardpoints and also held a provision to mount gunpods (2 x GSh-23L cannons each pod).
However, as quickly as the Su-15 arrived its operation days came to an end with the fall of the Soviet Union in 1991. The aircraft were taken out of Russian service by 1993 and scrapped or held in storage for the foreseeable future. Only Ukraine continued their use up until 1996 by which time the line was made all but obsolete by a new generation of combat aircraft - namely Mig-29s and Su-27s.
In one of the more infamous public tales involving an Su-15 and the West, the Soviet directed interceptor engaged Korean Air Flight 007 near Moneron Island and killed all 269 aboard.