Sukhoi Su-7
The Sukhoi Su-7 (NATO designation Fitter) was a swept wing, turbojet-powered fighter-bomber used by the Soviet Union and its allies.
Development
The prototype, designated S-1 'Strela,' first flew on 7 September 1955, and was first revealed to the world at the 1956 Aviation Day at Tushino. Its wing planform was devised during the Korean War by TsAGI, the Soviet aeronautics bureau. It was a 62-degree swept wing with Fowler flaps, conventional tail, and Sukhoi's distinctive petal-style rear-fuselage air brakes. The very large, area ruled fuselage was built around the dimensions of the Lyulka AL-7 turbojet, with 90 kN (19,840 lb) afterburning thrust. Despite its dimensions, internal volume for fuel and avionics were extremely limited. The engine was fed by a nose-mounted intake with a translating shock cone containing the SRD-5M ('High Fix') ranging radar.
The Su-7, given the NATO reporting name 'Fitter-A,' was originally intended as a fighter to counter NATO's F-100 Super Sabre and F-101 Voodoo fighters, in service with the USAF. It was armed with two NR-30 30mm cannon in the wing roots, with 70 rounds per gun. In keeping with the vogue for unguided rocket armament, early models had provision for an under-fuselage rocket pack, but this was quickly abandoned. As the Su-7B, the 'Fitter' soon found its metier as a ground-attack fighter-bomber, entering frontline service in 1958.
The Su-7's combat capabilities were limited. With a tiny internal fuel volume (2,940 l or 647 Imperial gallons), its operational radius, even with drop tanks, was poor -- seldom more than about 300 km (188 miles), and it had almost no useful range at all with maximum ordnance. Take-off and landing speeds were also very high, requiring long runways. Su-7BMLs had provision for JATO, but this only made logistics even more complicated, so it was rarely used. An additional problem with early models was that the afterburner took six to seven seconds to light, a handicap in combat.
In its favor, the 'Fitter' was very easy to fly, with docile handling characteristics. Its controls were notoriously heavy, but it was forgiving and predictable. The thirsty engine provided exceptional rate of climb and low-level speed. Furthermore, the entire aircraft was extraordinarily tough and robust, easy to service and cheap to operate (except in fuel consumption). Despite its limitations, it was popular with pilots. The Su-7 saw combat service in the Six Day War in 1967, the War of Attrition, and conflicts between India and Pakistan. Although used mostly in the ground attack role, an Indian Air Force Su-7 did shoot down a Pakistani F-6 (Chinese copy of the MiG-19) in 1971.
The limitations of the Su-7, particularly in take-off distance, led the Soviets to pursue the swing-wing Su-17, but the Su-7 remained in service through the 1980s. It was exported in the thousands to all Soviet Bloc and Warsaw Pact nations as well as many other air forces. In addition to the USSR, users were: Afghanistan, Algeria, Bangladesh, China, Czechoslovakia, Egypt, India, Iraq, North Korea, Poland, South Yemen, and Syria.
Variants
The initial production version was the Su-7B, a ground-attack fighter-bomber. In this role it carried bombs and rockets on underwing pylons (in Soviet service it could also carry tactical nuclear weapons). Two side-by-side fuselage pylons were reserved for drop tanks. The outer pylons were rated for 500 kg (1,105 lb), later increased to 750 kg (1,657 lb); the inners for 500 kg (1,105 lb). With tanks maximum load was only 1,000 kb (2,210 lb) total.
The Su-7B was superceded in production 1963 by the Su-7BM, with a more powerful AL-7F-I engine with 98.1 kN (21,627 lb) thrust, and then by the Su-7BML in 1965, which attempted to improve the 'Fitter's' rough field capability with larger, low-pressure tires, provision for rocket-assisted take-off with two SPRD-110 JATO rockets of 29.4 kN (13,300 lb) thrust, and an unusual set of ski attachments for the main landing gear for snow or mud use. It also added twin braking parachutes. The export models were the Su-7BMK and the Su-7BLK. respectively. A combat-capable two-seat trainer was also built, the Su-7U (NATO 'Moujik').
A prototype swing-wing version, the Su-7IG, became the basis for the later Su-17.
Specifications (Su-7BLK)
General Characteristics
- Crew: one, pilot
- Length: 17.38 m (57 ft 0 in) (including probe)
- Wingspan: 9.313 m (29 ft 3 in)
- Height: 4.8 m (15 ft 9 in)
- Wing area: 27.6 m² (297 ft²)
- Empty: 8,360 kg (18,360 lb)
- Loaded: 12,000 kg (26,450 lb)
- Maximum takeoff: 13,500 kg (29,760 lb)
- Powerplant: 1x Lyulka AL-7F-I afterburning turbofan
- Thrust: (dry) 68.65 kN (15,134 lb); (afterburner) 98.10 kN (21,627 lb)
Performance
- Maximum speed: (low) 1,150 kph (715 mph); (high) 1,700 kph (1,056 mph)
- Range: 1,450 km (900 miles)
- Service ceiling: 15,160 m (49,700 ft)
- Rate of climb: 15,200 m/min (29,900 ft/min)
- Wing loading: 434.8 kg/m² (89.1 lb/ft²)
- Thrust-to-weight: 0.73:1
Armament
- 2x NR-30 30mm cannon (70 rounds per gun)
- four wing and two underfuselage hardpoints for up to 1,000 kg (2,205 lb) of stores, typically including 250 kg (550 lb) and 500 kg (1,100 lb) general-purpose bombs, S-24 rockets, and UB-16-57U 57mm rocket pods
Related Content
Designation sequence: Su-7 - Su-9 - Su-10 - Su-11 - Su-15
See also: