Sukhoi Su-7


The Sukhoi Su-7 is a swept wing, supersonic fighter aircraft developed by the Soviet Union in 1955. Originally, it was designed as a tactical, low-level dogfighter, but was not successful in this role. On the other hand, the soon-introduced Su-7B series became the main Soviet fighter-bomber and ground-attack aircraft of the 1960s. The Su-7 was rugged in its simplicity, but its Lyulka AL-7 engine had such high fuel consumption that it seriously limited the aircraft's payload, as even short-range missions required that at least two hardpoints be used to carry drop tanks rather than ordnance.

Design and development

After Joseph Stalin's death, the Sukhoi OKB was reopened and by the summer, it began work on a swept-wing front-line fighter. The first prototype, designated S-1, was designed to use the new Lyulka AL-7 turbojet engine. It was the first Soviet aircraft to utilize the all-moving tailplane and a translating centerbody, a movable inlet cone in the air intake for managing airflow to the engine at supersonic speeds. The aircraft also had a wing sweep of 60°, irreversible hydraulically boosted controls, and an ejection seat of Sukhoi’s own design.
The S-1 first flew on 7 September 1955 with A. G. Kochetkov at the controls. Fitted with an afterburning version of the AL-7 engine after the first eleven flights, the prototype set a Soviet speed record of 2,170 km/h in April 1956. The prototype was intended to be armed with three 37 mm Nudelman N-37 cannons and 32 spin-stabilized 57 mm unguided rockets in a ventral tray. The second prototype, S-2, introduced some aerodynamic refinements. Testing was complicated by the unreliable engine, and S-1 was lost in a crash on 23 November 1956, killing its pilot I. N. Sokolov. Only 132 have been produced between 1957 and 1960, and the aircraft entered service as Su-7 in 1959.

Su-7A fighter

The first production variant: a frontline fighter that saw limited operational use in the Far East from 1958. However, in 1959, a decision was made to prioritize production of the MiG-21, thus less than 200 Su-7As were deployed. The Su-7A was retired in 1965 with operational deployment.

Su-7B fighter-bomber

On July 31, 1958, Soviet tactical aviation tasked Sukhoi with developing a ground-attack variant of the Su-7, which could replace the scrapped Ilyushin Il-40. The resulting prototype, designated the S-22, incorporated structural refinements for low-altitude operations at high-speed. The prototype first flew in March 1959; entering service in 1961 as the Su-7B.
Operationally, Su-7s were hampered by a high landing speed of 340–360 km/h. This was dictated by the highly swept wing. Combined with poor visibility from the cockpit and the lack of an instrument landing system, operations were very difficult, especially in poor weather or airfields. In 1961–1962, Sukhoi experimented with blown flaps on S-25 but the benefit was too small to warrant implementation. JATO rockets tested on S-22-4 proved more useful and were incorporated into the Su-7BKL. Attempts to improve takeoff and landing performance eventually resulted in the variable geometry Sukhoi Su-17.
The Su-7B and its variants became the main Soviet ground-attack aircraft of the 1960s. They were also widely exported. However, the very short combat radius and need for long runways limited the Su-7's operational usefulness. On the other hand, despite its notoriously heavy controls, the Su-7 was popular with pilots for its docile flight characteristics, simple controls and considerable speed even at low altitudes. It also had a reputation for easy maintenance.
In 1977–1986 the Su-7s remaining in Soviet service were replaced by Su-17s and MiG-27s.

Operational history

Egypt

The Su-7 saw combat with Egypt in the 1967 Six-Day War, the subsequent War of Attrition, and saw use in the Yom Kippur War by the Egyptians to attack Israeli ground forces.

India

The Indian Air Force used the Su-7 extensively in the 1971 war with Pakistan. Six squadrons, totaling 140 aircraft, flew almost 1,500 offensive sorties during the war, and undertook the bulk of the daytime attack missions. The IAF managed to retain a very high operational tempo with its Su-7s, peaking at a sortie rate of six per pilot per day. Fourteen or nineteen Su-7s were lost during the war, mostly due to anti-aircraft fire. After the war, it was found that the aircraft had high survivability, being able to fly home safely despite receiving heavy damage. For example, Wing Commander H.S. Mangat's Su-7 was badly damaged by a PL-2 missile fired by a Pakistan Air Force F-6. The impact was so severe that half the rudder was missing, the elevators, ailerons, and flaps were severely damaged, and half the missile was stuck in the chute pipe. The pilot made it back to his base. The death of at least one Indian pilot can be attributed, at least indirectly, to poor cockpit design. A pilot had moved his seating forward to a dangerous position, "because he found the bombsight and the front gun sight easier to operate" while in that position and was killed on ejection.
Indian Su-7BMKs shot down at least two Shenyang F-6s in the 1971 war, while losing three Su-7s to F-6s according to Pakistani sources, mostly during bombing runs.

Variants

A total of 1,847 Su-7 and its variants were built.
;Su-7A
;Su-7B
;Su-7BM
;Su-7BKL
;Su-7BMK
;Su-7U
;Su-7UM
;Su-7UMK
;Su-7IG
;100LDU Control Configured Vehicle

OKB-51 designations

;S-1
;S-2
;S-22
;S-22-2
;S-22M
;S-22KL
;S-23
;S-22-4
;S-25
;S-25T
;S-26
;S-22MK
;U-22
;U-22MK
;S-3
;S-41
;T-1
;T-3

Operators

Current operators

Former operators

  • Afghan Air Force – 24 Su-7BMK and 16 Su-7U trainers, were delivered to Afghanistan from 1972. Constant fighting, a high accident rate in the high altitude and poor maintenance caused substantial attrition. An additional 79 used replacements from Soviet stocks were supplied during the 1980s. None remain in service.
  • Algerian Air Force – 40 Su-7BMK.
  • Czechoslovak Air Force – the Czechoslovak Air Force was the first foreign operator of the Su-7 in 1963. Totals included 64 Su-7BM, 31 Su-7BKL and Su-7U. During operations service, 30 aircraft were lost in accidents. The remaining aircraft were phased out in 1990.
  • Egyptian Air Force – The first batch of 14 Su-7BMK was destroyed during the Six-Day War. From 1967–1972, Egypt received an additional 185 Su-7BMK/SU-7UMK. Those which survived the Yom Kippur War with Israel were retired in the mid-1980s.
  • Indian Air Force – 140 were delivered in 1968, equipping six squadrons. An additional 14 attrition replacements were provided. The last aircraft were retired in 1986.
  • Iraqi Air Force – The first contract for up to 34 Su-7BMK was signed in 1965, with deliveries starting in the spring of 1967. An additional order for 20 Su-7BMK was signed in July 1967. No longer in service.
  • Polish Air Force – operated 6 Su-7BM, 33 Su-7BKŁ and 8 Su-7U from July 1964 until June 1990; no longer in service.
  • Soviet Air Force
  • Syrian Air Force – Shortly after the Six-Day War of 1967, Syria received 25 Su-7s. During the 1973 Yom Kippur War, Syria lost most of the aircraft supplied. After 1973, The Soviet Union resupplied Syria with 35 more aircraft. By the mid 1980s, the Su-7 had been transferred to the reserves, and by the 1990s were decommissioned.