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Sukhoi Su-7

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For the World War II mixed-power prototype, see Sukhoi Su-6.
Su-7
Su-7BKL
Role Fighter-bomber/Ground-attack
Manufacturer Sukhoi OKB
First flight 7 September 1955
Introduction 1959
Retired 1986 (Soviet Union)
Primary user Soviet Air Force
Produced 1957-1972
Number built 1,847 (mainly Su-7B series)
Developed into Sukhoi Su-17

The Sukhoi Su-7 (NATO designation name: Fitter-A) was a swept wing, supersonic fighter aircraft developed by the Soviet Union in 1955. Originally, it was designed as tactical, low-level dogfighter, but was not successful in this role. On the other hand, soon-introduced Su-7B series became the main Soviet fighter-bomber and ground-attack aircraft of the 1960s.

Design and development

Original Su-7 fighters

On 14 May 1953, after Joseph Stalin's death, the Sukhoi OKB was reopened[1] and by the summer, it 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 engine. 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.[2] The aircraft also had a dramatic wing sweep of 60°, irreversible hydraulically boosted controls, and an ejection seat of OKB's own design.[1]

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.[2] 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.[2] 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.[1] Only 132 had been produced between 1957-1960, and the aircraft entered service as Su-7 in 1959.

Su-7B series of fighter-bombers

On 31 July 1958, Soviet tactical aviation (Frontovaya aviatsiya, фронтовая авиация) tasked Sukhoi with developing a ground-attack variant of the Su-7, that 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.[2]

Operationally, Su-7s were hampered by a high landing speed of 340-360 km/h,[3] 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.[4] 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.

Operational history

Original Su-7 fighters

The front-line fighter version saw limited operational use in the Far East, being retired in 1965.[1] They never saw combat.

Su-7B series of fighter-bombers

Su-7s of the Polish Air Force.

Su-7B and its variants became the main Soviet ground-attack aircraft of the 1960s. They were also widely exported (691 planes[1], including also some trainers). In 1977-1986 aircraft remaining in Soviet service have been replaced by Su-17 and MiG-27.

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 (IAF) used the Su-7 extensively in the 1971 war with Pakistan. Six squadrons, totaling in 140 aircraft, flew almost 1,500 offensive sorties during the war,[3] 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.[3] Fourteen Sukhois were lost during the war, mostly due to AA fire.[3] After the war was over, 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 an enemy MiG-19. 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.[3] The pilot made it back to his base, while Pakistan air force reported this incident as a kill.

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.[5]

Variants

The S-26 on display at Monino
Su-7BKL landing gear with the unique skid, and a UB-16 57 mm rocket launcher
A two seat trainer variant Su-7UMK (NATO designation: Moujik)

A total of 1,847 Su-7 and its variants were built.[1]

Su-7
First production version. The only production version that was a tactical air superiority fighter. Factory designation S-2. Manufactured 1957-1960 with 132 built. Remained in operational service until 1965.
Su-7B
The first ground-attack version, factory designation S-22. Manufactured 1960-1962 with 431[6] built.
Su-7BM
Upgraded AL-7F-1 engine, upgraded fuel system with external piping on either side of the fuselage spine, fuel tanks installed in the wings, "wet" underwing hardpoints for carrying external fuel tanks, capable of carrying tactical nuclear bombs. Manufactured 1963-1965 with 290[6] built.
Su-7BKL
Rough-field capable variant with skids affixed to the sides of the main landing gear, provision for two SPRD-110 JATO rockets of 29.4 kN (13,300 lbf) thrust, and twin brake parachutes. Introduced in 1965, factory designation S-22KL. Manufactured 1965-1972 with 267[6] built.
Su-7BMK
A simplified export version of Su-7BM. Manufactured 1967-1971 with 441[6] built.
Su-7U (NATO Moujik)
Two-seat trainer version of the Su-7B with reduced fuel capacity. First flight 25 October 1965. Manufactured 1966-1972 in parallel with the export version, designated Su-7UMK.
Su-7UM (NATO Moujik)
Two-seat training version of the Su-7BM.
Su-7UMK (NATO Moujik)
Two-seat training version of the Su-7BMK. All Su-7 trainers amounted to 411[6] built.
Su-7IG
Experimental variable geometry wing aircraft which was developed into Sukhoi Su-17.
100LDU Control Configured Vehicle
A Su-7U modified with canards and a longitudinal stability augmentation system. It was designed as a testbed for a fly-by-wire system for the Sukhoi T-4. It was later used in 1973–1974 during the development of the Su-27's fly-by-wire system.

OKB-51 designations

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.
S-22
OKB-51 designation for the Su-7B production aircraft.
S-22-2
OKB-51 designation for the prototype of the Su-7BM.
S-22M
OKB-51 designation for the Su-7BM production aircraft.
S-22KL
OKB-51 designation for the Su-7BKL production aircraft, incorporating the Short field equipment tested on the S-22-4.
S-23
As a pre-cursor to the S-22-4 tests, the S-23 was tested with a pure ski undercarriage and with skis on the main legs only
S-22-4
An S-22 tested with wheel / Ski undercarrriage, brake Parachute and SPRD-110 JATO boosters for rough/unpaved field operations.
S-25
This aircraft was used for Boundary Layer Control (BLC) tests, with compressor bleed air blown over the leading edges to reduce field length.
S-25T
A Su-7 fitted with the Boundary Layer Control system, rigged especially for use in a full-scale wind tunnel.
S-26
A continuation of the S-22-4 testing with wheel/ski undercarriage, double brake parachute and JATO boosters (The S-26 survives on display at the Russian Air Force Museum, Monino).
S-22MK
A simplified export version of the Su-7BKL, designated Su-7BMK
U-22
A belated trainer version with two seats in tandem in an extended nose based on the Su-7BM.
U-22MK
OKB-51 designation for the export version of the Su-7U, designated Su-7UMK by the VVS
S-3
A projected interceptor version of the S-2, with 'Izumrud' radar and avionic equipment in a re-configured nose section.
S-41
OKB-51 designation for the an experimental version of the S-1/S-2 with a lengthened nose and area-ruled rear fuselage.
T-1
A delta-wing tactical fighter project, based on the S-2, cancelled with the prototype nearly complete.
T-3
A delta-winged interceptor version of the S-2, developed in parallel to the S-3 and T-1. This would eventually lead to the T-43 prototype of the Su-9 interceptor.

Operators

Military operators of the Su-7
Blue = Current Dark Red = Former

Current operators

 North Korea
 Vietnam

Former operators

 Afghanistan
  • Afghan Air Force - 46, including 16 Su-7U trainers, were delivered to the Afghan Air Force from 1972. Substantial replacement deliveries during the 1980s may have raised the total number of aircraft to serve to about 120. None remain in service.
 Algeria
 Czechoslovakia
  • Czech Air Force - The Czech Air Force operated 60 aircraft, last Su-7s were phased out in 1990.
 Egypt
 India
 Iraq
 Poland
  • Polish Air Force - 46 were operated by the Polish Air Force, no longer in service.
 South Yemen
  • South Yemen Air Force
 Soviet Union
 Syria

Specifications (Su-7BKL)

Data from Green[2], Sukhoi[1]

General characteristics

  • Crew: One
  • Fuel capacity: 3,220 kg (7,100 lb)

Performance

  • Thrust/weight: 0.71
  • Takeoff roll: 950 m (3,120 ft)
  • Landing roll: 700 m (2,300 ft)

Armament

  • 2 × 30 mm Nudelman-Rikhter NR-30 cannon, 80 rounds each
  • Up to 2,000 kg (4,410 lb) on six hardpoints, typically including two 950l or 600 l (160 US gal) fuel tanks under the fuselage, and a combination of 250 kg (551 lb) or 500 kg (1,102 lb) bombs and 57-mm spin-stabilized unguided rockets in UB-16-57U pods. A 8U69 5-kiloton nuclear bomb could be carried on the left fuselage hardpoint. Some versions could also carry two 600 l underwing drop tanks.

See also

Related development

Aircraft of comparable role, configuration, and era

Related lists

References

Notes
  1. ^ a b c d e f g "Sukhoi Su-7." Sukhoi Company Museum. Retrieved: 28 January 2011}}
  2. ^ a b c d e Green, William and Gordon Swanborough. The Great Book of Fighters. St. Paul, Minnesota: MBI Publishing, 2001. ISBN 0-76031-194-3.
  3. ^ a b c d e "A whale of a fighter: Su-7 in IAF service." bharat-rakshak.com. Retrieved: 28 January 2011.
  4. ^ Nijboer and Dan Patterson 2003. pp. 174–177.
  5. ^ Dikshit, Mohan B. "To Err is Human Case Reports of Two Military Aircraft Accidents." SQU Med J, Volume 10, Issue 1, 2010, pp. 120–125.
  6. ^ a b c d e Goebel, Greg. "Sukhoi Su-7." Aviation Vectors, 1 August 20009. Retrieved: 28 January 2011.
  7. ^ "Su-7." IAF History. Retrieved; 28 January 2011.
Bibliography
  • Nijboer, Donald and Dan Patterson. Cockpits of the Cold War. Eden Prairie, Ontario: The Boston Mills Press, 2003 ISBN 1-55046-405-1.
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