On 14th May 1953, by order of MDI No 223, P.O. Sukhoi was appointed to replace V.V. Kondratyev as Chief Designer of the OKB-1 design bureau, which had been set up a year before to copy the US F-86 "Sabre" fighter. By MAI Order No 135 of 26th October 1953, the OKB-1 design bureau was assigned a branch of plant No 155 (MAI's former plant No 51) to be used as its production facility.
As of summer 1953, the Design Bureau was engaged in designing supersonic fighters in two configurations: swept and delta wing (letter designations "S" and "T" respectively). Officially, the go-ahead for the work was given by a decree of the government of 5th August 1953.
The conceptual design for a swept-wing front-line fighter (version S-1) passed preliminary design review in November 1953, and a mock-up committee review in February 1954. Six months later, in August 1954, a swept-wing fighter/interceptor (S-3) design also passed review, but work on that version was discontinued shortly thereafter.
The design of the S-1 aeroplane and systems incorporated a variety of innovations: a wing with 60º sweep in the ¼ bisecant line, all-movable CS, adjustable axial nose air intake, new high-performance AL-7F turbojet (developed by OKB-165 design bureau) with projected afterburning thrust of 10,000 kg, hydraulic system with operating pressure of 210 kg/cm², a power control system, dual-chamber boosters, a proprietary-design ejection seat, and other features.
The prototype was built in June 1955, and delivered to FRI on the night of 15th July. The S-1 flight-test team was headed by leading engineer V.P. Baluyev. A.G. Kochetkov from GNIKI was appointed the leading test pilot under an agreement with the Air Forces as the Design Bureau had no in-house pilots as yet. On 27th July the aircraft performed its first taxiing, with its maiden flight taking place on 7th September 1955. The first stage of the manufacturer's testing was performed using the AL-7 engine (i.e., AL-7F without afterburning) and was completed in January 1956, a total of 11 flights having been performed. Beginning March 1956, GNIKI test pilot V.N. Makhalin continued S-1 testing with the operational AL-7F.
By that time, the OKB-155 Design Bureau (Designer General A.I. Mikoyan) had started testing of the first prototypes of the future MiG-21. The MAI leadership, in an attempt to showcase the high capabilities of new aircraft of domestic origin, tacitly encouraged competition between the two design bureaus. The first to "make it" was the Design Bureau of P.O. Sukhoi: on 9th June, a S-1 test flight recorded a flight speed of 2,070kph, which was 270kph higher than the performance requirement (PR)! As a result, a decree of the government of 11th June 1956, ahead of governmental testing, put the aircraft into small-batch production at plant No 126 in
Komsomolsk-on-Amur under the designation Su-7. On 24th June 1956, together with other new aircraft from the Soviet aviation, the S-1 was publicly unveiled during the traditional air display at Tushino. The building of a second prototype, S-2, had been completed by the autumn of 1956, with its flight testing starting in October.
Official testing of the Su-7 started in September 1956 and continued, on and off, till December 1958. The main problems were due to the extremely unreliable performance of AL-7F engine. This was specifically the cause of the writeoff of the first prototype on 23rd November 1957 and resulting death of Air Forces GNIKI test pilot I.N. Sokolov. As a result, the AL-7F Su-7 variant had a limited production run, it having been recommended to outfit the aircraft with an upgraded engine version, the AL-7F-1. The Su-7 front-line fighter was manufactured from 1957 to 1960, with a total of 132 aeroplanes produced (production runs 1 to 12). The first series Su-7s were put into operational service in the summer of 1959 with the fighter regiment stationed at the Vozdvizhenka aerodrome. In 1959-60, the regiment was used for service testing of the aeroplane. The Su-7 fighters were in service with USSR Air Forces and ADF in the Far East till 1965.
In the second half of the '50s, the USSR armed forces scrapped its ground attack arm. Nevertheless, the Air Forces still had to provide battlefield support for the foot soldiers. The MiG-15 and MiG-17 were used as a stop-gap substitution for the Il-10, but that was a makeshift solution, and it was clear that frontline aviation needed a special-purpose strike aircraft. In this context, the Air Forces having put in a suggestion to this effect in 1957, the OKB-51 design bureau was given the job of developing a Su-7-based fighter-bomber, the Su-7B. Officially, the go-ahead for development was given by a decree of the government of 31st July 1958. The building of the first prototype, C22-1, was completed at the end of 1958. In March, the aeroplane was flown with an AL-7F engine; fitted with an operational AL-7F-1, the aeroplane's first flight, with the design bureau's test pilot Ye.S. Solovyov at the controls, was performed on 24th April 1959. The manufacturer's tests of the aeroplane were completed in September 1959. State Integration Tests (SIT) were conducted between December 1959 and May 1960, with two prototypes used at the same time starting January 1960. The Su-7B was put into production at plant No 126 in Komsomolsk-on-Amur in 1960, starting with production run 13; it was manufactured till late 1962. The first production Su-7Bs were put into service with 4th CEC of Air Forces in Lipetsk in the summer of 1960, the separate aviation regiment stationed at the Martynovka airfield being the first combat unit in the Air Forces to be rearmed with the Su-7B; from January to October 1961, the airfield was used to conduct service testing of the fighter-bomber. In the light of the testing results, a 24th January 1961 resolution of the government put Su-7B into service.
The SIT findings cited the Su-7B's low flight range as one of its major shortcomings. At the beginning of 1961, the second prototype, S22-2, underwent appropriate modification: its wings were fitted with fuel bays, with underwing pylons engineered to support external fuel tanks. The manufacturer's tests of the aeroplane were conducted between May and September 1961, with official tests held in October-November 1961. The variant with increased fuel tankage and improved avionics line-up was produced under the designation Su-7BM from 1963 to 1965. The Su-7BM fighter-bomber became the first aircraft of the Su-7 series to be exported: in 1964, the USSR sent the first flight of 12 Su-7BMs to Czechoslovakia. Besides Czechoslovakia, Su-7BMs were delivered to the Air Forces of Poland. This way, the USSR's closest Warsaw Treaty allies were armed with the same aircraft as the Air Forces at home.
For deliveries to other countries friendly to the USSR, the Design Bureau developed in the mid-90s a special export version of the aeroplane. The pilot production-run prototype of the Su-7BM export version had been built at the production plant by March 1966. After verification testing, the aeroplane was put in production in 1967 under the designation of Su-7BMK ("K" standing for "commercial" in Russian). Planes of this type were exported in the period between 1967 and 1971 to 7 countries: Algeria, Afghanistan, Iraq, India, the Korean People's Democratic Republic (North Korea) and United Arab Republic (Egypt and Syria). In the inventory of the Air Forces of those Middle East states, the aeroplanes were deployed in combat operations during the Arab-Israeli wars and hostilities of 1967-73, and in India's Air Force, during the Indo-Pakistan conflict of 1971.
A major shortcoming of the entire Su-7 aircraft family was poor takeoff and landing characteristics (TOLC), which were entirely due to the aerodynamic configuration selected, featuring as it did a relatively slender sharply-swept wing. This resulted in high takeoff and landing speeds, requiring therefore a long runway. With a view to improving the Su-7B's TOLC, the Design Bureau investigated a variety of solutions. Thus, in the period 1960-61, the Su-7 was used as a platform to develop and build an experimental aeroplane, the S-25, which featured a blown flap based on a blowing-type boundary layer control (BTBLC) system with air tapped from behind the engine compressor. The plane underwent manufacturer's tests in the period 1961-62, yet the BTBLCS failed to bring about a sufficient reduction in the takeoff/landing speed so it was not recommended for production. Improvement of the baseline aircraft TOLC was achieved using another solution, validated on the experimental S22-4. Between 1960 and 1963, this aircraft was used to try out a suspension powder rocket booster to provide faster acceleration during takeoff, and innovative larger braking parachutes to cut down the landing run. The solutions were recommended for production.
Another innovation introduced by the Design Bureau was ski-equipped landing gear designed to improve the takeoff/landing performance of frontline aircraft deployed from unpaved airstrips with soft surfaces. The Design Bureau had been doing experimental research in this area since 1956. With the Su-7 and Su-7B used as the platform, several prototypes were built with ski undercarriage, viz. S-23 and S-26, which were then tried out on a variety of unpaved and snow-covered aerodromes between 1959 and 1966. The skis installed on the Su-7B's main struts proved highly effective on unpaved runways and were recommended for production and operational use, but it was another version, the so-called wheel-ski undercarriage, tried out on S22-4, that was finally put into production. This way, S22-4 became the prototype of the last mass-produced variant of the baseline aircraft, which received the designation Su-7BKL (short for "wheel-ski"). The Su-7BKL replaced the Su-7BM on the production line in Komsomolsk-on-Amur in 1965, the later variant having been produced till 1972. A flight of Su-7BKLs was exported to Czechoslovakia and Poland.
A Su-7B-based two-seat combat trainer aeroplane was developed by the Design Bureau in 1962, but with the Design Bureau using its branch based at the Komsomolsk-on-Amur production plant to build it, it took a long time to complete: the first prototype aeroplane, U22-1, was not flight-tested until 25th October 1965, with the design bureau's test pilot Ye.K. Kukushev at the controls. The manufacturer's tests of the aeroplane were carried out under a tight schedule, in just two months, with the official tests completed in May 1966. The Su-7U two-seat trainer was produced from 1966 to 1972, with an export version, the Su-7UMK, manufactured over the same period. Interestingly, Su-7Us were delivered not only to Air Force regiments armed with the Su-7, but also to ADF units with Su-9 and Su-15 interceptors in the inventory, as the latter units were often suffering from a shortage of two-seaters such as the Su-9U and Su-15UT.
A total of 1,847 Su-7-type planes of all versions and variants were made over the entire production period, with 691 planes exported to 9 countries. The Su-7B type aircraft was kept in the inventory of the USSR Air Forces till the mid-'80s, with up to 25 combat units of fighter-bomber aviation (FBA) equipped with such aircraft during the period of peak deployment in the late '60s - early '70s. Beginning in 1977, the Su-7Bs were gradually replaced in FBA regiments with Su-17 and MiG-27 type aeroplanes.
The Design Bureau and FRI used the Su-7B to try out several flying laboratories, viz.:
- 100LDU developed on the Su-7U platform to test the system for remote control of the T-4 ("100”) missile carrier and the Su-27 fighter.
- FL for testing new Su-7U-based rescue aids.
Su-7B-type aircraft performance specifications