Sukhoi Su-7

Les Sukhoi Su-7 sur Wikipedia de langue anglaise

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The Sukhoi Su-7 (NATO designation name: Fitter-A) was a swept wing, turbojet-powered fighter-bomber used by the Soviet Union and its allies.

Design and development

On 14 May 1953, the Sukhoi OKB was reopened and initially tasked with copying the American F-86 Sabre fighter.

By the summer, the OKB began work on a swept-wing tactical fighter for establishing air superiority over the battlefield (frontovoi istrebitel, фронтовой истребитель, front-line fighter in Soviet terminology).

The first prototype, designated S-1, was designed to use the new Lyulka AL-7 turbojet and it was the first Soviet aircraft to utilize the all-moving tailplane and a translating centerbody, a movable 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 11 flights, the prototype set a Soviet speed record of 2,170 km/h (1,170 kn, 1,350 mph, Mach 2.04) in April 1956.

The prototype was intended to be armed with three 37 mm Nudelman N-37 cannon and 32 spin-stabilized 57 mm (2.25 in) 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.

The aircraft entered service as Su-7 in 1959, although it saw only limited operational use.

On 31 July 1958, Soviet tactical aviation (Frontovaya aviatsiya, фронтовая авиация) tasked Sukhoi with developing a ground-attack version of the Su-7.

The resulting S-22 retained the basic layout of its S-2 predecessor, incorporating primarily structural refinements for high-speed low-altitude operations. It first flew in March 1959, and began entering service in 1961 as the Su-7B.

A total of 1,847 Su-7 and its variants were built, of which 691 were exported.

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. The six Indian Su-7 squadrons 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, managing a sortie rate of six per pilot per day.

Fourteen Sukhois were lost during the war, mostly due to AA-fire as IAF pilots conducted multiple passes over targets with insufficient fuel, but the type had acquitted itself well. After the war was over, it was found that the aircraft had received heavy AA fire in service , but still managed to fly home safely.

Unconfirmed report mentions, one pilot RG Kadam of TACDE had shot down an F-86 Sabre flown by FL AJ Siddiqu, but was shot down by WC Hashmi, before he could make it back to base.

However the kill was not mentioned by the Indian air force because it was not reported by the pilot.

Similarly Wing Commander HS Mangat's Su-7 was badly damaged by a Sidewinder missile fired from an enemy MIG-19, the impact was so severe that it removed the flaps, airelons, & half the missile was stuck in the chute pipe.

The pilot made it back to his base, while Pakistan air force reported this incident as a kill.

Operationally, Su-7s were hampered by high takeoff and landing speeds dictated by the thin, highly-swept wing.

The landing speed of 450 km/h (245 kn, 280 mph) combined with poor visibility from the cockpit and lack of an instrument landing system made for difficult operations, especially in poor weather.

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.

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.

Variants

S-1

(Strelovidnoye [krylo] – swept wings) OKB-51 designation for the first prototype of the Su-7 / Su-9 family.

S-2

OKB-51 designation for the first production version of the Su-7.

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