Sukhoi Su-17 / Su-20 / Su-22 (Fitter) Ground Attack / Strike Fighter Aircraft
The Soviet Sukhoi Su-17 Fitter - and its export derivatives, the Su-20 and Su-22 - were swing-wing developments of the original Su-7 Fitter fixed-wing design.
Authored By Captain Jack; Content ©www.MilitaryFactory.com
The Mach 2-capable Sukhoi Su-17 "Fitter" was a further development of the successful Su-7 "Fitter-A" fighter/fighter-bomber family line detailed elsewhere on this site. The aircraft incorporated a partial variable geometry wing ("swing wing") system and improved upon the former's take-off and landing attributes as well as performance at the low-level as required of it during ground attack runs. The swing-wing element added to the aircraft's stability at low-speeds and altitudes while improving overall range and ordnance loads by featuring large-area fixed wing "gloves". Beyond its new wing arrangement, the Su-17 also differed from its Su-7 origins in that it featured a newly-designed canopy and nose assembly as well as an identifiable raised fuselage spine, giving the new aircraft a more stout appearance than the pencil-thin Fitter-A. The type served the Soviet Union well and was heavily exported to Warsaw Pact nations and trusted Third World allies alike. The Su-17 was developed into the export Su-20 and Su-22 Fitter models of varying avionics, engines and weapons. In all, some 2,867 Su-17/Su-20/Su-22 Fitters were produced with almost half of these made available to Soviet export customers. Over a dozen nations took delivery of the type, making it a staple fighter-bomber throughout the Cold War. Some air forces continue to fly the aircraft - nearly forty years after it was introduced.
Development - Fitter-B
The Su-7 (NATO codename of "Fitter-A") was a capable aircraft in its own right. However, there were glaring deficiencies in its operational range - no thanks to a thirsty powerplant - and ordnance-carrying capabilities. Sukhoi and Soviet authorities sought other improvements that would make the Fitter series a much more capable and versatile battlefield component. As such, a Su-7BM production model served as the demonstrator for the testing of a new swing-wing variable geometry system development. The new wing would essentially be made up of two parts - a fixed wing root/wing glove and the positional swing-wing portion making up half of the wing (at about mid-wing span). The new prototype became the Su-7IG ("IG" for "Izmenyaemaya Geometriya", also internal designation of "S-22I"). First flight was achieved on August 2nd, 1966. The working prototype/technology demonstrator showed enough promise during this testing phase, improving on both field performance and range of the Su-7, that it was selected for production.
A two-seat Su-7U long-fuselage trainer was then revised. The rear instructor's cockpit would make way for additional avionics and fuel while housing the new wing component. The swing-wing configuration was devised as a way to increase the Su-7's inherent range while at the same time allowing the aircraft to carry more weaponry along its fixed wing portion without the need to implement heavy and complex swiveling weapon stations to maintain aerodynamic integrity in full sweep. A limited production run appeared under the base "Su-17" designation, these being fitted with the Lyulka AL-7F-1 turbojet powerplant of 22,046lbs thrust. Production of this early Fitter-B would run from 1969 to 1973.
The Su-17K became the export version of this base Su-17, though this was only received by the Egyptian Air Force. NATO assigned the new aircraft design the codename of "Fitter-B", sequentially relating this new design with that of the original Su-7 it originated from.
The Rest of the Su-17 Fitter Variants - Beginning with Fitter-C
The Su-17M (S-32M) became the first quantitative production version of note and was known to NATO as "Fitter-C". The aircraft was fitted with an afterburning Lyulka AL-21F-3 engine of 24,800lbs output and was given an onboard SRD-5M range-finding radar (same as the one found on the Su-7BMK production models). A new navigation and attack system was installed for her intended ground attack role. The fuselage was also given a pair of forward-mounted pitot pressure measurement tubes. An Angle-of-Attack (AoA) vane was affixed as was a rear brake parachute, the latter promoting shorter landing runs. First flight was achieved on December 28th, 1971. In addition to her primary battlefield roles, some Su-17s were developed into a limited-production - though still capable - reconnaissance variant under the Su-17R designation featuring reconnaissance pods with applicable equipment. Production of the improved Fitter-C began in 1972 with official introduction occurring in 1973. Production ceased in 1975.
The export version of this ground attack model became the Su-20. The prototype Su-20 first flew on December 15th, 1972. Egypt, Poland and Syria were the primary export customers of this new aircraft. The Su-20R was the export reconnaissance equivalent of the base Su-20 line.
The Su-17M2 was the next definitive development and was assigned the NATO codename of "Fitter-D". She was essentially an improved production form of the former types and was known internally at Sukhoi as S-32M2. The nose assembly was extended by 15 inches and revised to incorporate more of a downward slope to improve the pilot's "out-of-the-cockpit" forward visibility - a plus in the low-level strike role. This new Fitter also deleted the ranging radar but incorporated the Fon-1400 laser rangefinder as well as additional combat-related avionics. A DISS-7 Doppler navigation radar was installed into a fairing under the nose and first flight of the aircraft was achieved on December 20th, 1973. Production began in 1974, lasting until 1977, and the Su-17M2 officially entered Soviet service in 1975. The Su-17M2 featured a fixed shock cone.
The Su-17M2D was another Fitter-D development but fitted with a Tumansky R-29BS-300 series engine of 25,335lbf with afterburning in a revised rear fuselage (this being a defining feature of the variant) and shorter overall fuselage. The engine offered little in the way of improved performance and limited range so was therefore only offered in forthcoming export deliveries. First flight was achieved on January 31st, 1975 and production lasted from 1977 to 1978.
Fitter-E - the Trainer
The Su-17UM was the two-seat trainer form developed from the S-52U prototype and given the NATO codename of "Fitter-E". Production began in 1976, with the aircraft entering service that same year. Production lasted until 1978. This new aircraft featured a deeper revised airframe to make room for the addition of the second cockpit for the instructor. This also resulted in the deletion of some internal fuel space thus limiting the aircraft's range. The original avionics of the production model were maintained while the portside cannon was omitted. The vertical tail fin was enlarged to counteract the effects of longitudinal instability (when in a high AoA). First flight was achieved on August 15th, 1975.
The two-seat Su-17UM went under the export designation of Su-22U and fitted a Tumansky R-29 series powerplant.
The Su-17M2D export model became the Su-22 which fell under the internal Sukhoi designation of S-32M2K. The Su-22 was afforded the same K-36D ejection seat system as found on the modern-day MiG-29 "Fulcrum" and Sukhoi Su-27 "Flanker" jet aircraft series and was powered by a Tumansky R-29 engine. The Su-22 also featured a fixed shock cone, laser rangefinder and Doppler radar.
The Lyulka-powered Su-17UM3 (S-52UM3, NATO codename of "Fitter-G") was a revised conversion trainer with the deeper fuselage and revised vertical tail fin. It fitted the avionics suite of the Su-17M3 and achieved first flight on September 21st, 1978. Production lasted from 1978 until 1982.
The export form was offered as the Su-22UM3 and the Su-22UM-3K, each differing by their use of the Tumansky R-29 and Lyulkin AL-21 series engines respectively.
The Su-17UM two-seat trainer airframe was also used in the development of the S-52, becoming the Su-17M3 ("Fitter-H"). The instructor's cockpit position was naturally removed and made way for additional avionics and fuel stores, the latter benefitting range. The external Doppler radar fairing was moved into an internal position and provision for AA-2 "Atoll and AA-8 "Aphid" along two hardpoints under the wing gloves were added. First flight was achieved on June 30th, 1976. Production lasted from 1976 until 1981. The Su-17M3 (and its related export derivatives) model became the most quantitative Su-17 Fitter development of the series, numbering nearly 1,000 production examples in whole.
A downgraded export version of the Su-17M3 became the Su-22M ("Fitter-J", S-52K internal Sukhoi designation). The prototype Su-22M was first flown on May 24th, 1977 with production beginning in 1978 and lasting to 1984. An upgraded export version fell under the designation of Su-22M3 (internal designation of S-52MK).
The Su-17M4 (internal designation of S-54 and NATO codename of "Fitter-K") became the final Fitter production form. First flight was achieved on June 19th, 1980. The avionics were vastly improved and the Su-17M4 featured the "Sirena" SPO-15LE radar-warning system as well as the Lyulka AL-21F-3 engine. Engine cooling was addressed through the implementation of fuselage- and vertical tail-mounted air inlets to help promote better cooling airflow around the engine and jet pipe, a prime consideration for an afterburning powerplant. The shock cone was fixed into position and provisions were added to support both anti-radiation and air-to-surface missiles. Production lasted from 1981 into 1988.
The Su-17M4 was offered to export customers under the Su-22M4 designation (internal designation of S-54K). Production lasted from 1983 to 1990. The Su-17M4 was given a top speed of 1,155 miles per hour (Mach 1.7) at altitude with a combat range of 715 miles (1,430 miles ferry). The service ceiling was limited to 46,590 feet while the rate-of-climb was listed at 45,275 feet per minute.
Modernized Export Su-22 Fitters
The Su-22 line was later offered a modernization package making these Fitters Su-22M5s. This upgrade incorporated Russian- and French-based systems consisting of an all-new digital cockpit with Hands-On Throttle and Stick (HOTAS), a Phazotron/Thomson-CSF "Phathom" radar system, GPS navigation and an overall improved avionics suite as well as compatibility with TV and laser-guided munitions. Lahav of Israel installed Elta synthetic aperture radar systems and new digital computers into Polish Su-22s.
One-Off Su-17 Fitter Developments
The Su-17 was used in a few "one-off" developmental projects as well, these becoming the Su-17M-28 and the Su-17MKG. The Su-17M-28 was used in the testing of the AS-9 "Kyle" anti-radiation missile whilst the Su-17MKG became the development platform for the testing of the AS-10 "Karen" and AS-14 "Kedge" air-to-surface missiles. Both aircraft platforms would lend themselves well into expanding the lethality of the Su-17 Fitter line as a whole, particularly in its ability to acquire and destroy ground-based targets with a good level of success.
To the casual observer, the Su-17 series appeared externally similar to the preceding Su-7 Fitter line. The most obvious change was its use of a swept fixed-wing area housing the swing-wing portion of the wing assembly. This would allow the new Su-17 to carry more ordnance around its center of gravity while leaving the rest of the wings the freedom to provide for better range and performance through the various intended flight actions (take-off/landing/low-performance flight, cruise and high-performance flight). Wing sweep positions were set at 28-, 45- and 62-degrees respectively. Wings were low-mounted with slight anhedral (downward slope) along the cylindrical fuselage and fitted with a pair of large boundary layer fences running longitudinally from leading edge to trailing edge (the fences were affixed on the static portion of each wing glove and not the sweeping wing portions).
The fuselage featured a cut-off nose assembly housing an integral shock cone. Air was drawn through the nose-mounted inlet and around the shock cone to feed the single engine buried within the fuselage. The pilot's seating position was placed well-forward in the design, affording him good views of the action to all sides with the exception of the rear, this being partially blocked by the raised fuselage spine. The spine ran from the rear of the canopy base to the base of the single vertical tail fin topping the empennage. The empennage featured highly-swept horizontal tailplanes complimenting the swept wing gloves and vertical tail fin. The horizontal planes straddled either side of the single engine exhaust ring. The undercarriage (retained from the original Su-7 construction) was fully-retractable and made up of two single-wheeled main landing gear legs (retracting inwards toward centerline) and a single-wheeled nose landing gear leg (retracting forward).
Standard armament (Su-17M4) was a pair of 30mm Nudel'man-Rikhter NR-30 series cannons (80 rounds of ammunition to a gun). The Fitter was given twelve total hardpoints (in later production models) for which to affix a variety of air-to-air and air-to-ground stores (two underwing hardpoints were reserved for self-defense air-to-air missiles while four hardpoints were positioned along the underfuselage sides and three hardpoints were given to each underside wing glove area). In the air-to-ground role, the Fitter was cleared to carry AS-7 "Kerry", AS-10 "Karen", AS-11 "Kilter", AS-12 "Kegler" and the AS-14 "Kedge" air-to-surface missiles as well as conventional drop bombs, laser-guided/electro-optical bombs, napalm, drag chute bombs, cluster bombs, gun pods (GSh UPK-23 and the traversable GSh SPPU-22)) and rocket pods. The Fitter was cleared to carry the AA-2 "Atoll", AA-8 "Aphid" and AA-11 "Archer" air-to-air missiles (mainly in a self-defense role). External armament was limited to 8,820lbs.
Beyond the Soviet/Russian use of the Su-17 fitter and its related export developments, the new design was shipped off to nations across Asia, North Africa and the Middle East with some ending up in southern Africa and Western South America (Peru). Operators included Armenia, Afghanistan, Algeria, Angola, Azerbaijan, Belarus, Bulgaria, Czech Republic, Czechoslovakia, East Germany (later Germany), Egypt, Hungary, Iraq, Iran, Libya, North Korea, Peru, Poland, Slovakia, Syria, Turkmenistan, Ukraine, Uzbekistan, Vietnam and Yemen. Some of these air forces still use their Su-20/Su-22 Fitters in an operational capacity. Perhaps of note in this listing was use of the Su-17 by Peru. Russia has since withdrawn their Su-17s from operational service beginning in 1998, these final forms being of the reconnaissance type.
Su-17 Fitters Over Afghanistan
The Soviet invasion of Afghanistan in the 1980s put the Su-17 fitter into action (the earlier Su-7 was also fielded in the conflict as was the Mikoyan-Gurevich MiG-23 "Flogger" and Sukhoi Su-25 "Frogfoot"). While achieving solid results in the early going, the tough operating conditions of the South Asian desert inevitably took their toll on the sensitive internal components of the Fitter. However, the Fitter was available in quantity and seemed to tolerate these conditions best when compared to the comparable close-support air-based weapons on hand. However, its low-level attack prowess were done in somewhat by the aircraft's inherent operating speed. The inclusion of shoulder-based SAM systems (such as the American-based Stinger missile systems into the conflict) forced the Fitters to higher operating altitudes and thusly degrading combat effectiveness. The arrival of the dedicated ground-attack MiG-27 "Flogger" (a fighter-bomber development of the air superiority-minded MiG-23 "Flogger") forced the Su-17s to more secondary roles by the end of the conflict.
The Su-17 was unofficially known as the "Martlet" (or "Strizh" in Russian).
Two Sukhoi Fitters of Libyan origin were shot down by US Navy Grumman F-14 Tomcats in the much publicized Gulf of Sidra incident (August 19th, 1981).
The USAF could lay claim to at least six Sukhoi Fitters during the 1991 Gulf War.