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Su-15 FLAGON (SUKHOI)

The Sukhoi Su-15 Flagon all-weather interceptor was withdrawn from Russian service about 1992. Although the aircraft was built in the 1950s, it remained a formidable aircraft with several upgrades, and was built in large numbers. Its speed is in excess of Mach 2.4 and carries large missiles on the outboard portion of the wings. The aircraft's wings are mid-mounted delta with square tips. There are two turbojets in the fuselage and two exhausts. The fuselage is rectangular from the air intakes to the tail. The nose is bullet-shaped nose and has a bubble canopy. The tail is swept-back and has a tapered fin with a square tip. The flats are swept-back, tapered, and mid-mounted on the fuselage.

In 1967, nine new fighters were demonstrated to westerners at the Domodedovo show. Competitivedesigns were apparent among a number of variable-geometry wing and VSTOL aircraft. Most of the new designs had high speed capabilities in excess of Mach 2. However, two complementing designs appeared which had potential application to strategic air defense-the Su-15 and the MiG-25.

The Su-15 appears to be the earlier of the two designs to fly, in 1962 [western estimates had been that the first flight was probably in 1964 or 1965]. It appears to have been intended for replacement of the aging fleet of Su-9/11 aircraft. As such it is a short-range interceptor having a moderately high altitude capability. It features side engine inlets which facilitate a large radome and a sufficient size to accommodate the electronics associated with an advanced automated data link system. As another example of design inheritance, it featured stabilizers, wing sections, canopy, missiles, and radome from the predecessor Su-11. The engine derived from late-model MiG-21's.

The neglect of range and avionics requirements may be illustrated by the Soviets reluctance to abandon nose inlets. These require that a large proportion of the fuselage be used for ducting which obviated internal space for fuel and electronic gear. It was not until the Tupolev fighter that the Soviets resorted to side inlets to release a large volume for fuel and electronics in the fuselage. Notably, both the Su-15 and MiG-25 also feature side inlets.

It is noteworthy that, thus far, there appear to have been no competing aircraft prototypes associated with either the Su-15 or the MiG-25 requirements. The tradition of design competition was much in evidence in 1967 with respect to variable-geometry wing and VSTOL aircraft, but the two PVO aircraft were evidently developed in complementary, non-competitive programs. Competitive designs, if there were any, were abandoned before prototype construction-possibly at the stage of design approval or mock-up.

The development of this aircraft began in the spring of 1960 as part of the effort to upgrade the Su-11 (T-47) interceptor, fitted with the AL-7F-2 type engine, based on the solutions developed under the scrapped T-3M (T-37) fighter/interceptor programme. The project was given the name Su-15 and work-in-progress designation T-58. The upgrading project provided for the aircraft to be given a capability to intercept targets at a wider range of altitudes and flight speeds, including in head-on approach (forward hemisphere interception). Moreover, the research scope covered an option of rendering all major intercepting procedures automatic, with an autopilot system specified for the aircraft.

The T-58 initial configuration underwent a radical transformation compared to the T-47: for the nose to accommodate a higher-performance radar, the axial nose air intake with shock-cone centre body was replaced on the new fighter with lateral variable ramp intakes with a vertical airbrake. Later on, in the context of the requirements to improve the aircraft's reliability, the single-engine configuration was discarded in favour of a configuration with two R-11F-300 type engines. As a result, the Su-15 acquired the streamlined look of a classic supersonic fighter of the class of 2nd-generation jet aircraft.

The building of a prototype was completed early in 1962, with the maiden flight of the T58D-1 prototype taking place 30 May 1962 (test pilot V.S. Ilyushin). The aircraft's State Integration Tests (SIT) were conducted under a tight schedule between August 1963 and June 1964; unlike the tests on the Su-9 and Su-11, they were completed without any serious faults found. The SIT findings cited low range as the only material weakness. To remedy the situation, the Su-15 was provided with increased fuel tankage, its fuselage having been streamlined at the wing roots and the "waistline" featured on the prototypes taken in.

On 30 April 1965 the aircraft was put into service as part of the Su-15-98 intercept capability based on the Su-15 (T-58) host aircraft, a weapons system with RP-15 (Oryol-D-58) radar unit and R-98 rockets in two variants: with semi-active radar target seeker and passive IR target seeker, as well as a ground-based component, the Vozdukh-1M type guidance system. This way, the Su-15 became the Design Bureau's third interceptor, after the Su-9 and Su-11, to be mass-produced and put into service as part of an intercept capability.

The Su-15 went into production in 1966 at a plant in Novosibirsk where it replaced the YaK-28P on the production line. The maiden flight of the Su-15 pre-production prototype took place on 6th March 1966, with the plant's test pilot I.F. Sorokin at the controls. In 1967, the planes began to be delivered to combat units of the ADF. The first unit in USSR's Armed Forces to be rearmed with the Su-15 was the fighter aircraft regiment of the ADF Moscow district, which was deployed at the Dorokhovo airfield. It was not until after production had started that the Su-15 received a boundary layer blowing control (BLBC) system to improve its takeoff and landing characteristics.

The Yak-28P and the Su-15 were both produced at the same factory. During the Soviet period, the OKBs only did design and flight test work with workshops for building prototypes. The designs were then handed off to independent factories for production. The the Novosibirsk aircraft factory No. 153 was responsible for the Yak-28P production, and then assigned production of the Su-15 once it had passed its State acceptance trials in 1962. Given that both the Yak-28P and the Su-15 used the same powerplant and radar, producing both at the same plant made logistical sense.

A total of about 1,300 Su-15-type airplanes were produced at the Novosibirsk aircraft plant. There were no operational upgrades of the Su-15 to speak of, apart from the fact that in the late '70s - early '80s the entire operational stock of the machines underwent modification to accommodate 2 R-60-type close-in action rockets suspended underwing on additional pylons.

In the late '60s - early '70s, the Su-15 interceptors together with the Su-9 and Su-11 formed the fist of the air arm of the USSR ADF troops as mainstream state-of-the-art interceptors. By the mid-'70s, i.e., during the period of peak deployment, the Su-15 was in the inventory of 29 fighter aircraft regiments, which accounted for more than a third (!) of the operational air units of the ADF troops. Su-15 (Su-15TM) type aeroplanes were kept in the inventory of the ADF troops and USSR Air Forces till 1991; in the inventory of the RF Armed Forces, till 1994; in Ukraine, through 1996. The last combat unit to be equipped with Su-15 type planes was the aviation regiment of Ukraine's Armed Forces stationed at the Belbek aerodrome in the Crimea.

Su-15 type aircraft were instrumental in intercepting a great number of intruders into the USSR's airspace. The first of such intercept engagements on Su-15 took place in 1970, when on the night of 11th September a pilot of the 62th FAR escorted to his home airfield a Greek Douglas DC-3.

The widest media coverage was given to 2 instances of "shoot-down" deployment of the Su-15. The first incident took place on 20th April 1978 in Karelia, when a South Korean Boeing 707, en route from Paris to Anchorage, violated the USSR's airspace around Murmansk. The intercept mission of a Su-15TM aircraft was flown by a pilot of the ADF's 431st FAR, Cpt A.I. Bosov. All attempts to persuade the Boeing 707 into a forced landing having failed, the pilot was ordered to shoot down the intruder and fired a R-98MR missile at it, following which the damaged Boeing landed on the iced over Korpiyarvi lake. In the course of the incident fragments from the exploding rocket killed 2 passengers and wounded 10.

The second incident took place on the night of 1st September 1983, when another passenger jet, a Boeing 747 flying the Anchorage-Seoul route, was intercepted and shot down in the Far East. The action to intercept the aircraft, which had strayed into USSR airspace over Kamchatka and Sakhalin involved, among others, a pilot of the 777th FAR, Major G.N. Osipovich, who took the Su-15 aircraft on alert off the ground and was ordered to shoot down the intruder. It is believed that the incident brought about the death of 269 people onboard the Boeing 747.

What is less known is the fact that a Su-15 was used to perform a successful ramming maneuver. On 18 July 1981, the USSR's Transcaucasian airspace was penetrated by a CL-44 type transport aeroplane inbound from Iran. The intercept mission was flown by two of the 166th FAR's Su-15s, one of the planes piloted by Cpt V.A. Kulyapin. Given the time constraints of the situation, with the intruder about to escape across the border, Kulyapin, having been ordered by ground control to prevent it, had to engage by ramming it, following which he succeeded in saving himself by ejecting. The pilot was decorated with the Order of the Red Star for his heroism.







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