Sukhoi S-32 / Su-7IG / S-22I / Su-17 / Su-20 / Su-22 / Fitter
The Su-17 (S-32) single-seat ground attack fighter was the product of a process of incremental redesign of the Su-7B (S-22).
Derived from the swept-wing Su-7 Fitter A (NATO code name), essentially by fitting variable-sweep outboard wing panels, the Su-17 was first revealed in 1967, and labelled ‘Fitter-B’ by NATO but dismissed as a research version.
Under the leadership of Nikolai Zyrin, the Sukhoi OKB adapted an Su-7BMK as a low risk, low cost variable wing geometry demonstrator. Mid-span pivot points were introduced so that the outer wing panels could be sweptback from 28 degrees to 45 degrees and 62 degrees positions. As the Su-7IG (Izmenyaemaya Geometriya, or variable geometry), or S-22I, the demonstrator flew on 8 August 1966, proving the efficacy of the variable-geometry arrangement and providing the basis for a production aircraft, the Su-17. This entered the VVS-FA inventory in 1970.
The Su-17 was powered by the Lyulka AL-21F-3 turbojet with a military power of 7800kg and 11200kg with afterburning. Maximum external stores load was 4000kg distributed between nine external stations, and built-in armament comprised two 30mm cannon.
Not until the mid-1970s did it dawn on the West that the modification, together with a more powerful but fuel efficient engine and new avionics, had resulted in a vastly improved aircraft with doubled weapon load, 30 per cent greater range and substantially better short-held take-off characteristics. So successful has been the aircraft that numerous versions are in service with Frontal Aviation, the Soviet naval air arm, Warsaw Pact and left-leaning countries abroad.
An upgraded version, the Su-17M (S-32M), entered production in 1974, this having a drooped and lengthened – by 38cm –fuselage nose with ventral Doppler navaid pod. This, like the preceding Su-17, was exported as the Su-20 (S-32MK), recipients including Algeria, Egypt, Iraq, North Korea, Vietnam and Poland.
By 1972 the initial Fitter B version was in limited service. Sukhoi Su-17 variants based in eastern Europe and the USSR have been progressively improved from the basic Fitter-C.
Whereas the Fitter-B had been a straightforward adaptation of the Fitter-A airframe, the Fitter-C took the process of incremental design development a stage further. The wing remained basically similar to that of the v-g prototype but was now mated with a derivative engine of the original AL-7F series turbojets. This, the similarly-dimensioned AL-21F, offered a respectable increase in power and a modest improvement in SFC. A nominal increase in internal fuel capacity was acquired by adopting the deeper fuel-housing dorsal spine that had been introduced by the two-seat Su-7U as a means of compensating for some of the ill-afforded loss in tankage that had inevitably accompanied the introduction of a second seat in a dimensionally barely lengthened (by 12 in/30cm) fuselage.
The result was a tactical fighter capable of lifting from much shorter airstrips almost double the ordnance load and carrying it some 25-30 per cent further. A multi-role warplane toting respectable payloads over reasonable radii. This was more than could be claimed for the preceding fixed-geometry Fitter- A, the good low-level gust resistance and manoeuvrability, and highly-regarded handling qualities of which the Fitter-C reputedly retained. Within little more than two years of its FA debut, Fitter-C was being exported to WarPac countries and Middle Eastern recipients of Soviet military aid.
The export version of Fitter-C was referred to by its recipients as the Su-20, and there is some evidence to suggest that this designation is also used by the V-VS. Su-20s were in service with the air forces of Algeria, Czechoslovakia, Egypt, Iraq, Libya, Syria and Poland.
Fitter C was the first series production model, with the Lyulka AJ-21F engine. The Fitter C was supplied to Warsaw Pact and other allies as the Su-20. Replacing the Fitter C was the ‘Fitter D’, appearing in 1976, with its undernose terrain avoidance radar and a marked-target seeker in the inlet centre-body. The laser ranger was accommo-dated within the lower half of the intake centrebody and the fuselage nose was lengthened 1.25 ft (38 cm) to permit a flat, elongated-lozenge-shaped avionics housing to be mounted beneath the nose, ahead of the nosewheel bay, the aft end of this housing apparently accommodating doppler. No attempt would seem to have been made on Fitter-D to compensate for the inevitable destabilising effect resulting from this longer and deeper forebody.
A design change introduced with Fitter-F and to be retained by succeeding variants of the Sukhoi ground attack fighter was an increase in the diameter of the rear fuselage, this increase being vertically asymmetric. A conversion trainer, the ‘Fitter-E’, parallels the Fitter-G except for a slightly drooped forward fuselage and lack of a port wing root gun, whilst the ‘FitterG’ operational trainer has a taller, straight-topped fin and a marked-target seeker. Newest of the single-seat variants is the ‘Fitter-H’ which has the revised fin and a deep dorsal fairing behind the canopy, presumably for extra fuel tanks.
A further export derivative using the basic Su-17M airframe, but re-engined with a Tumansky R-29BS-300 augmented turbojet with a max thrust of 11500kg, received the designation Su-22 and was supplied to Angola, Libya and Peru. Featuring a deeper forward fuselage and enlarged spine, and a redesigned tail to restore yawing stability, yet a further single-seat version, the Su-17M-1, appeared in mid-1979. The Su-17M-2, which appeared almost simultaneously, differed in equipment fit, with the export version, the Su-22M-2, supplied to both Libya and Peru, having the Tumansky engine. The definitive single-seat production versions were the Su-17M-3 and M-4, the former supplied to Hungary as the Su-22M-3 and the latter to Afghanistan, Czechoslovakia, East Germany and Poland as the Su-22M-4. These AL-21F-powered models embodied much improved avionics and introduced extra stations for R-60 or R-73 close range AAMs.
Export versions of the Su-17 ‘Fitter-C have a reduced avionics fit and are designated Su-20, but when the Su-22 ‘Fitter-F’ appeared as a ‘Fitter-D’ counterpart, its bulged rear fuselage revealed a change of engine to the 11500-kg (25,353-lb) thrust Turnansky R-29B afterburning turbojet for even better performance. A ‘Fitter H’ counterpart, the Su-22 ‘Fitter-J’, is similarly powered and identified by a more angular dorsal fin. Su-22s are also employed as interceptors with AA-2 ‘Atoll’ AAMs. A Tumansky-powered two-seater has been noted in Soviet service, the Fitter E is a two-seat Su-17 with a drooped nose, a feature retained by the Fitter G trainer, which also introduced a deeper fuselage spine. Fitter H, a single-seater distinguished by its dorsal fairing and drooped nose, can carry two AS-7 Kerry radio-command air-to-surface missiles. The twin wing root-mounted 30-mm NR-30 cannon are retained by Fitter-H, which, like preceding variable-geometry Fitters, has four fuselage and four wing stores stations. Two of the fuselage stations – at least, on export examples (eg, Libya) – are “wired” for Atoll IR-homing AAMs, providing some defence capability. The inboard wing and the fuselage stores stations can each lift “iron” bombs of up to 1,102 lb (500 kg), and the former and two of the latter may be fitted with adaptor shoes for radio command guidance AS-7 Kerry ASMs, or the various anti-radiation missiles, such as AS-9.
Peru purchased its first Su-22s in 1976, comprising 32 single seat Su-22s and 4 two seat Su-22Us.
The latest version of the Su-17 ground-attack aircraft appeared in 1984. The Fitter K is distinguished by an intake extending forward of the fin root.
With more than 3,000 built, including two-seat training variants, production of the Su-17 terminated in 1984.
Su-17 Fitter C
Engine: 1 x Lyuika AL-21F
Installed thrust (dry / reheat): 76.5 / 110 kN
Span: 13.8 m / 10 m
Length: 18 m
Wing area: 40 sq.m
Empty wt: 10,000 kg
MTOW: 17,700 kg
Warload: 4000 kg
Max speed: 2200 kph
Initial ROC: 13,800 m / min
Ceiling: 18,000 m
T/O run: 1000 m
Ldg run: 600 m
Combat radius: 700 km
Fuel internal: 4000 lt
Air refuel: no
Armament: 2 x 30 mm
Hard points: 8
Su-17M-4 Fitter K
Max take-off weight: 19500 kg / 42990 lb
Wingspan: 10.04-13.66 m / 33 ft 11 in-45 ft 10 in
Length: 19.10 m / 63 ft 8 in
Height: 4.86 m / 16 ft 11 in
Max. speed: 2220 km/h / 1379 mph
Range: 2300 km / 1429 miles
Type: single-seat variable-geometry ground-attack fighter
Armament: two 30-mm NR-30 cannon (with 70 rpg) in wing roots
Hardpoints: four underwing and four underfuselage weapon pylons for up to 4000 kg (8,818 lb)
Powerplant: one 11200-kg (24,691-lb) thrust Lyulka AL-21F-3 afterburning turbojet
Maximum speed 2300 km/h (1,429 mph) or Mach 2.17 at altitude
Maximum speed 1285 km/h (798 mph) or Mach 1.05 at sea level
Initial climb rate 13,800 m (45,275 ft per minute)
Service ceiling 18000 m (59,055 ft)
Combat radius with 2000 kg (4,409 lb) of stores 630 km (391 miles) on a hi-lo-hi mission
Combat radius with 2000 kg (4,409 lb) of stores 360 km (224 miles) on a lo-lo-lo mission
Wingspan, extended (28 deg sweep) 14. 00 m (45 ft 11 in), fullyswept (62 deg) 10. 60 m (34 ft 9.5 in)
Length 18.75 m (61 ft 6.25 in)
Height 4.75 m (15 ft 7 in)
Wing area, extended 40.1sq.m (432 sq ft)
Su-22 Fitter F
Engine: Tumansky R-29
Su-22 Fitter J
Engine: Tumansky R-29