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Su-17 FITTER (SUKHOI)

The Su-17 Fitter with its variable sweep wings was developed from the fixed-wing Su-7B. The first public demonstration of it was made in 1969. It was in production for a long time (1970-1990) and many modifications were built. Some of the modifications were Su-17M, Su-17M2, Su-17M3, and the Su-17M4 (low-altitude subsonic bomber), Su-17UM (trainer). It was designed as a fighter-bomber, but it was used mostly as a bomber. The Su-17 remains an effective aircraft with capable avionics and impressive armament.

In 1960, the Su-7 fighter-bomber, which had very high characteristics for its time, was accepted into service with the Soviet army. However, the military did not like his landing speed, there were other comments on the design of the aircraft, its electronics and weapons.

In the mid-1960s, after the Su-7B was adopted, the designers were given a new task - to find ways to reduce the take-off and landing distances for this type of aircraft. Sukhoi tried to solve this problem with the help of starting accelerators and brake parachutes, but soon we came to the conclusion that a wing with variable geometry was necessary.

Seeking to improve low-speed and take-off/landing performance of the Su-7B fighter-bomber, in 1963 the Sukhoi OKB with input from TsAGI created a variable-sweep wing technology demonstrator. The TsAGI specialists, together with the designers of the Sukhoi Design Bureau, proposed an original wing design for the new aircraft: the angle was only changed by its cantilever part (about half the span). By turning only the outer section and thereby maintaining the minimum displacements of the centers of pressure and gravity as the geometry changed, the developers left the design of the Su-7B wing almost intact.

Thanks to this design, the fuselage of the original machine (Su-7) was practically not changed. The size of the center section was determined by the location of the main landing gear of the aircraft. In addition, this technical solution practically did not lead to a change in the centering of the machine when the wing was changed, the aircraft showed good stability at all angles of sweep over a wide range of speeds.

The Su-7IG (internal designation S-22I, NATO designation "Fitter-B"), converted from a production Su-7BM, had fixed inner portions of the wing with movable outer segments which could be swept to 28, 45, or 62. A fixed inner wing simplified construction, allowing the manufacturer to retain the Su-7 landing gear and avoiding the need for complex pivoting underwing hardpoints, and it minimized the shift in the center of pressure relative to the center of mass with change in wing sweep. The new wing also had extensive leading-edge slats and trailing-edge flaps. Su-7IG first flew on 2 August 1966 with V. S. Ilyushin at the controls, becoming the first Soviet variable geometry aircraft. Testing revealed that take-off and landing speeds had decreased by 5060 km/h (3137 mph) compared to the conventional Su-7.

The wings are mid- to low-mounted (wings are mounted below the center), variable, swept-back, and tapered with blunt tips. There are wide wing roots. There is one turbojet engine in the fuselage and a circular air intake in the nose. There is a large, single exhaust. The fuselage is long and tubular with a blunt nose and rear section. It has a large bubble canopy. There is a prominent dorsal spine on top of the body from the cockpit to the tail fin. The tail is swept-back and has a tapered fin with a square tip. The flats are mid- to low-mounted on the fuselage and swept-back and tapered.

At the end of 1965, the drawings of the fighter-bomber were transferred to production. August 2, 1966 a new aircraft took off. During the flight, the pilot shifted the wing several times. The successful course of testing allowed to show the new aircraft in the air parade in Tushino in July 1967. In November of the same year, the USSR Council of Ministers issued a decree on the start of mass production of the new machine in 1969. She received the name of the Su-17.

The Su-17 project as a whole was a simple and inexpensive technical solution, which significantly improved the flight characteristics of an existing vehicle. It also made it possible to easily, quickly and cheaply start mass production of a new aircraft at the plant, which previously produced the Su-7. Modernization expanded tactical capabilities of the aircraft, as well as increased the range of its use. However, the increase in the mass of the Su-17 almost negated all the improvements achieved on the experimental machines.

Serial production of the Su-17 (the aircraft received this designation) was adjusted only in 1969. Serial production of the Su-17 began at an aircraft factory in Komsomolsk-on-Amur, before that they produced the Su-7. The first subdivision into which the Su-17 began to enter was the 523rd Aviation Regiment of the Far Eastern Military District.

Su-17 showed the best flight performance compared with its prototype Su-7BM. The new fighter-bomber had a long range and its duration, despite the reduced volume of fuel tanks and an increase in vehicle mass, and its take-off and landing characteristics improved. Also, significant changes were made on-board electronic equipment of the aircraft. The most massive series went version of the Su-17M with the engine AD-21F-3. In 1975, the car was equipped with the latest weapons control equipment with a laser rangefinder and the KN-23 navigation system, which solved the problem of flight to the target and back automatically.

Airplanes of all modifications of the Su-17 were armed with two 30-mm guns NR-30, which were installed in the center section. There were also six pylons for the suspension of rocket-bomb armaments: two under the wings, and four under the fuselage. Modification of the Su-17M4 had ten pylons for the suspension of rockets and bombs. Her combat load was 4,250 kg. Modifications of the Su-17 and Su-17M had a PBC-2 bomb mount and a ASP-5ND-7 riflescope. A more modern ASP-17 rifle scope was mounted on the Su-17M2.

The last of the 'Fitter' series, the backbone of Russian ground attack squadrons since the 1960s, the 'Fitter-K' is designed to operate from forward airfields. Known as the Strizh (Marlet), it has a short range compared to most ground attack aircraft. It can carry four rocket pods - each 32x57 mm folding fin rockets - or four air-to-air missiles, or bombs. Or it may carry a wide range of guided weapons from the AS-7 'Kerry' command-guided missile to the AS-9 'Kyle' anti-radar missile. Due to problems in Afghanistan with shoulder fired heat-seeking missiles, the 'Fitter-Ks' have chaff and flare dispensers.

Production of the fighter-bomber continued until 1990. In total, more than 2,800 units of this combat vehicle were manufactured. The Su-17 is still in service with the air forces of Poland, Vietnam, Angola, Syria, Uzbekistan and Libya. Export versions of this aircraft are designated Su-20 and Su-22. The export versions can be distinguished by a deeper dorsal spine.




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