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 shortcomings included short range and light weapon load.
Design and development
Original Su-7 fighters
On 14 May 1953, 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 dramatic wing sweep of 60°, irreversible hydraulically boosted controls, and an ejection seat of OKB'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 cannon 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 had been produced between 1957 and 1960, and the aircraft entered service as Su-7 in 1959.
Su-7B fighter-bomber
On 31 July 1958, Soviet tactical aviation tasked Sukhoi with developing a ground-attack variant of the Su-7, which could replace the scrapped Ilyushin Il-10. The resulting prototype, S-22, incorporated structural refinements for high-speed, low-altitude operations. It first flew in March 1959, and entered service in 1961 as the Su-7B.Operationally, Su-7s were hampered by a high landing speed of 340–360 km/h, as dictated by the thin, highly-swept wing. Combined with poor visibility from the cockpit, and lack of an instrument landing system, it made operations very difficult, especially in poor weather or on poor 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 Su-7BKL. Attempts to improve takeoff and landing performance eventually resulted in the Sukhoi Su-17.
Su-7A fighter
The front-line fighter version saw limited operational use in the Far East from 1958, but by 1959, a decision was made to proceed with production of the MiG-21, and less than 200 units were deployed. The Su-7A was retired in 1965. They never saw combat.Su-7B fighter-bomber
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 its 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-17 and MiG-27.
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, totalling 140 aircraft, flew almost 1,500 offensive sorties during the war, and undertook the bulk of the daytime attack efforts. 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 Su-7s were lost during the war, mostly due to AA fire. After the war, it was found that the aircraft had a high survivability, being able fly home safely despite receiving heavy damage. For example, Wing Commander H. S. Mangat's Su-7 was badly damaged by a Sidewinder missile fired from Pakistan Air Force J-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 set his seating at a dangerous position "because he found the bomb sight and the front gun sight easier to operate" while in that position, and was killed on ejection.
Indian Su-7BMK shot down at least two Shenyang J-6 in the 1971 war. While lossing 3 Su-7 to the J-6
Variants
A total of 1,847 Su-7 and its variants were built.;Su-7
;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
- North Korean Air Force – received at least 28 Su-7BMK/-7UMK in 1971. The aircraft were ordered in 1969.
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 – 20 Su-7BMK and 8 Su-7UM.
- 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 October 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 units were retired in 1986.
- Iraqi Air Force – Iraq received 18 Su-7BKL in 1968, with 83 more subsequently delivered. 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. In the October War of 1973, 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.
Specifications (Su-7BKL)