Archive digitization

Aviation and Diplomacy

Frank Piasecki

NATO 1949-2009 Projekt ekspozycji w Muzeum Lotnictwa Polskiego w Krakowie

Polish Aviation Museum

31-864 Kraków,
al. Jana Pawła II 39
phone: (12) 640 99 60,
(12) 642 40 70

a cultural institution of the Malopolska Region

Małopolska – Kraków Region


Kraków Airport

Aeroplane: WSK Lim-6bis (NATO: Fresco)

WSK Lim-6bis (NATO: Fresco)
USSR / Poland
ground attack plane

  • Technical data

Span 9.63 m
Length 11.26 m
Take-off weight 5354 kg
Maximum speed 1130 km/h
Ceiling 16,470 m
Range (with additional fuel tanks) 1670 km
Armament see text
Powerplant :
VK-1F turbojet, rated at 3380 kg (with afterburners)


At the turn of the 40's and the 50's, the Soviet Union produced the MiG-15 fighter. Though the aircraft featured very good performances for that time, designers were aware of the necessity of its constant improvements.
The Mikoyan and Guryevich 153 Experimental and Construction Bureau started the works on the MiG-15 bis modernisation, aiming at increasing the top speed with unchanging the powerplant. The only way to reach that goal was the use of wings and stabilisers with a bigger angle of sweep. The project was realised under the "SI" call sign, known also as the "MiG-15bis 45°". The construction underwent several changes. Wings received a 45°, flowing into a 42° sweep at the external part. Leaving the front of the fuselage unchanged, the rear was extended for 90cm, an increasing stability fin ventral fin was added, an enlarged surface and aileron hydraulic amplifiers were applied.
The Wk-1 turbojet engine was left unchanged. The armament, similar to that of the MiG-15, consisted of one 37mm cannon and two 23mm cannons. Two external fuel tanks or two 50kg or 100 kg bombs were also envisaged.
The new aircraft was flown in January 1951. The test flights confirmed an increasing of speed for 40 km/h, however it also resulted in a drop of range, worsening of manoeuvrability and an extended take off and landing distance.
During the tests, the fuselage was sealed, which increased speed further. During one of the flights, the speed of sound was broken. Unfortunately, a series of successes was broken by a catastrophe on the prototype, caused by the destruction of part of the horizontal stabiliser.
Following tests were continued with the second prototype. During the consecutive tests, the so-called "aileron reverse" disclosed, caused by the wing's insufficient rigidity in some phases of flight. It was an extremely dangerous aerodynamic effect, requiring improvement. All these problems were gradually eliminated. The construction was certified as a new aircraft and in October 1951, there came a decision of introducing the aircraft into serial production as the MiG-17, produced by five manufacturers. Improvements followed, introduced into production instantly. Another time, the shape and the area of air brakes were changed. To improve visibility to the rear, the back part of the cockpit was changed (later, a periscope was also applied) and new radio equipment was added.
During production, the new Wk-1A engine with a bigger service life was applied. These modifications caused an unofficial change of the aircraft's name to the MiG-17A. The frontal MiG-17 fighter became an escort fighter as well.
In the Soviet Union, five manufacturers produced 5467 aircraft.
In sequel, the works on improving manoeuvrability features continued. The way to achieve it was an engine with bigger thrust. Such an engine unfortunately was not available. All the capabilities of increasing the thrust of the Wk-1 engine were already used.
A new solution consisted in attaching an afterburner to the engine had to be utilised. This is a device connected to an engine?s exhaust system. Its working consists of the combustion of extra fuel in exhaust gasses. Alas, by the significant rise of thrust, the fuel consumption rises rapidly. In 1949, a group of specialists in the 155 Experimental and Construction Bureau with co-operation with the Central Institute of Aeronautical Engines, worked out a suitable afterburner. In 1951 the work was crowned with the appearance of the Wk-1F engine. The engine was tested on the "SF" aircraft, which became the prototype of the aircraft's new version, named the MiG-17F. The significant changes consisted of the rear part of the fuselage, housing the afterburner chamber. Once again the air brakes were changed. According to expectations, there came the improvement of the aircraft's performance (climbing speed, horizontal flight speed, ceiling and manoeuvrability). The gunnery armament remained unchanged. The bomb load was increased up to 500kg (2 x 250kg). Unfortunately in this time, entering the world of high transonic and supersonic speeds, problems associated with flying couldn't be avoided e.g. some problems with the afterburner's durability also appeared.
After correcting the defects and aerodynamic problems, the MiG-17F was introduced into serial production in September 1952. The consecutive production series were constantly improved, the pilot's conditions, as well as the ejection seat were improved, a new fuel installation, enabling the engine's stabile work, was replaced and the hydraulic amplifiers engaging ailerons and vertical control systems were improved. The firing control system was enriched with distance measuring equipment, connected with an optical gun sight.
Based on the MiG-17F, the reconnaissance MiG-17R version produced in limited numbers, was created. Two manufacturers produced 1685 aircraft.
Parallel with the works on the frontal MiG-17, tests on the interceptor fighter equipped with a radar view finder, were carried out. Flight trials of the new aircraft, named the SP-2, started 1951. Armament consisted of two 23mm cannons. The "Korshun" radar sight used, appeared imperfect and the SP-2 didn't enter production.
In May 1952, work over the adaptation of the SP-7 aircraft to the new "Izumrud" radar sight started. A year later, the aircraft entered production under the MiG-17P designation.
The implant of the RP-1 radar sight caused a big change in the front part of the fuselage, in the electric installation and the cockpit fairing.
Armament consisted of three 23mm cannons (the derivatives of one 37mm and two 23mm cannons also came into use).
The MiG-17P was produced in a quantity of 225 examples, by one manufacturer.
In January 1951, the SP-7F powered with the Wk-1F engine, was flown. It entered production as the MiG-17PF. An increase of performance and manoeuvrability was acheived. Apart from the RP-1 gun sight, the RP-5 derivative with an increased range and bettered resistance to interference was utilised. Two manufacturers in the Soviet Union produced 668 MiG-17PF's.
The work on the arming the aircraft with guided RS-1U missiles (guided by a radio beam sent by the modified RP-1U, the K-5 system) and a radar gun sight were also carried out.
In 1956, 40 MiG-17PF aircraft were converted to the new armament system. The modernised fighter was named the MiG-17PFU. External stores consisted of four guided missile launchers. Most of the MiG-17PFU's were unarmed, a few being armed with a single, 23mm cannon. A few experimental aircraft which served as test beds for a new construction appeared. The tests of the new unguided systems, which could reinforce the gunnery and the bombing armament in attacking surface and the targets, were also carried out.
The MiG-17's taking part in several wars in Asia and Africa, very often surprised their opponents with their combat capabilities.
Retired fighters were converted into flying targets - the MiG-17M, the MiG-17MM, and the M-17. Production of all the MiG-17 versions ended 1958. It was continued in China and Poland. In China, production was realised in 1956-1959 under the J-5 designation. 767 examples were produced. In 1961, preparations for the MiG-17PF, named the J-5A started.
The freezing of political and commercial relationships between China and the Soviet Union delayed production, which started 1965. Based on the two seat school and training JJ-5 a version with a Wk-1A engine was developed. Production started 1966, which continued until 1986, producing 1061 aircraft.
In Poland the introduction of the MiG-17's into service was connected with the beginning of its licence production. In 1955, the Soviet Union handed over the completed documentation for the Mig-17F and the Wk-1F engine. Production of the fighter named the Lim-5 (factory designation "C") started in November 1956, at the Mielec works, ending in 1960. 477 aircraft were produced for domestic purposes and for export. Part of the batch was used for photo reconnaissance, a camera being built in a container under the middle section of the fuselage. Modified in this way, the Lim-5R appeared by the end of the 1950's. The Wk-1F engine was produced in Rzeszów, under the Lis-5 designation.
In January 1959, the MiG-17PF interceptor version, named the Lim-5P (factory designation "D"), was produced. After producing 129 examples, production ended 1960. By the end of the 1950's, the trials of converting the frontal MiG-17F into the fighter attack aircraft in Poland started. The modification was named the Lim-5M (factory designation "F"). Using this opportunity, the increase of range with external stores and improving take off and landing characteristics, started.
The time of flight was planned to be increased, thanks to the additional fuel in the tanks placed at the wing roots (fairing tanks) and to shorten the take off distance, JATOs were used. The brake chute was buried in the lower part of the fuselage. The aircraft could operate from unpaved runways, thanks to doubled main wheels, retracting into the fairing tanks. The possibility of improving the fuselage shape, according to area rule, aimed at decreasing wave drag, was also tested. This improvement, however, didn't enter production. The gunnery and bombing armament was similar to that of the Lim-5. Production of the Lim-5 lasted from November 1960 until May 1961. It ended with 60 examples built. The Lim-5M didn't enjoy a fine reputation in the air force, which is why work on further improvements continued. In the next modified aircraft, named the Lim-6 (factory designation "J"), an air chute, housed at the base of the vertical stabiliser, was applied. The doubled landing wheels were left unchanged, the shape of the fuel tanks was improved and blown flaps were used. The Lim-6 was introduced into production, realised in 1961 - 1962, in a quantity of 40 aircraft. However it didn't enter service, as the introduced changes didn't improve the aircraft's performance. In 1962 further tests continued. The Lim-6bis thus appeared.
Eventually, resigned from all the changes introduced to the Lim-5M and the Lim-6, leaving only the air chute placed at the base of the vertical rudder and the Lim-5 landing single main wheel landing gear. The external stores were placed on two hard points under the wings, close to the fuselage. The Lim-6bis started to enter service in March 1963. Initially, these were modified Lim-6's, followed by the modification of the Lim-5M. The next 70 Lim-6bis examples were new factory aircraft, with production ending in 1964.
Part of the batch consisted of the reconnaissance version, named the Lim-6bisR.
By the end of the 1960's, the Lim-5P's interceptors lost their combat capabilities.
In 1971, the decision of converting part of the aircraft fell through. The radar gun sight was removed (replaced by a battery) and two extra hard points (for unguided rockets, or bombs of 140kg for one hard point) were added.
The gunnery armament was similar to that of the Lim-5P (Mig-17PF). The aircraft emerged as a result of the rebuild and was named the Lim-6M, its reconnaissance derivative, the Lim-6MR.



Dofinansowano ze środków Ministra Kultury i Dziedzictwa Narodowego
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