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From ACIG.org ACIG Database
By 1960 the MiG-21F-13 - known to Mikoyan OKB as "Model 72" - was in mass production. Though a delightful aircraft to fly, with no vices and outstanding all-round performance and manoeuvrability, it suffered (like the F-104A and to some degree Mirage 3C) from being very limited in capability. The 2.470 litres of fuel carried in six aluminium tanks in the fuselage and four integral wing tanks could not all be used without running into problems of stability; the authorized limit was 2.340 litres. This so limited the endurance that it was virtually impossible to reach the theoretically attainable level speed of Mach 2. Moreover unlike the western counterparts no search radar was fitted and armament comprised just two K-13 close range missiles and one NR-30 gun with 75 rounds. Avionics comprised merely UHF and duplicated VHF radios and the usual SRO-2 series IFF a radio altimeter for use below 300m, a radio compass and the fixed ranging radar linked to gun sight. From the 115th aircraft (the first with broader fin) a radar warning receiver was added. In 1958 the People’s Republic of China had procured a license to manufacture the MiG-19SF and its R-9BF-811 engines. It was planned that a license for MiG-21F-13 and its R-11-300 engine would follow, but in the event the two countries severed relations in 1960 before any agreement had been concluded. Despite this the People’s Republic was determined to go into production with the MiG-21 as a matter of urgency. Bearing in mind the language problem, the severe shortage of trained engineers, the embryonic state of aircraft industry and the almost total lack of any supporting industry or underlying technology – extending even to provision of suitable raw materials – the fact that the task was accomplished in four years is little short miraculous. In China the aircraft received designation J-7 (J for Jianjiji – Fighting aircraft) and the engine the WP-7 (from Wopen – turbojet). The entire programme was assigned to the airframe and engine plants at Chengdu, in Sichuan. The drawings were almost all produced by working backwards from dissected parts of a MiG-21F-13 supplied from the Soviet Union just prior to the break. Despite this first flight was made successfully on 8 January 1965 (one report claims December 1964) and by late 1965 the J-7s were in service with PLAAF. By 1966 J-7s were being exported to Tanzania and Albania, but in that year the Cultural Revolution made conditions so chaotic the manufacture had to be stopped with over 60 delivered and about 20 more on the assembly line. Production gradually picked up again after 1972, reaching full rate in the fifth five year plan (1976-80). The aircraft in this batch were considerably improved, entirely as a result of Chinese original design effort, the designation becoming J-7-II or for export F-7B. The engine designated WP-7B, updated to dry and afterburning thrusts of 9.700Ibs and 13448Ibs respectively. This was achieved almost entirely through fitting a larger and more efficient afterburner with an improved by fitting a conical centre-body of refined profile translating in and out according to an infinitely variable schedule instead of having just three positions. The cockpit was redesigned with a completely new canopy hinging upwards at the rear and with a separate wind screen assembly at the front. The CS-1 seat, a Chinese copy of Soviet SK-1, was replaced by what became standard Chinese ejection seat, the HTY-4, usable at zero height and at speeds between 130 km/h and 850km/h. The chord of vertical tail was again increased and braking parachute revised in design and relocated in a tube at the base of rudder. Armament was increased the left gun called Type 30-I being reinstated, though ammunition capacity was reduced to 60 rounds per gun. And the centre line pylon was modified to carry a drop tank of 800 litres capacity, substantial numbers of F-7Bs were exported the largest being Egypt. The Chinese engineers then planned a further series of upgrades, and this, from 1980; they sought off-the-shelf equipment from western suppliers. One all Chinese development was the WP-7BM engine, with unchanged ratings but with no need of separate starting tank filled with gasoline. GEC Avionics of the UK supplied Type 226 Skyranger, an integrated communications systems and the Type 956 Hudwac (Head-up display and weapon-aiming computer) giving greatly improved management of weapon delivery, especially in attacks on surface targets. Extra pylons were added under the outer wings, plumbed for a 500-litre drop tank, while the inboard pylons were revised to permit carriage of Matra R550 Magic 1 or PL-7 missiles, rocket launchers ( 18 of 57mm or 7 of 90mm) or bombs of up to 500kg size. Recognition details that the instrument boom on the nose was moved from the bottom to top of the engine inlet. There were many other changes including numerous new or upgraded avionics items and an upgraded electrical system with four rotary inverters replaced by three static inverters. The resulting aircraft is designated for export as F-7M Airguard it has proved most successful despite the age of the design. Apart of from PLAAF it is in service with Pakistan, Bangladesh, Zimbabwe, Sudan the export total exceeded 500 by 1988. Aircraft for Pakistan are designated as F-7P Sky bolts. They incorporate about 20 changes specified by the customer, including Martin-Baker Mk 10L seats and wiring for four Magic, Sidewinder or Pl-7missiles. Even at the time of 1988 Chengdu was producing 20 F-7Ms per month a remarkable feat for a fighter of basic design over 30 years earlier. The Chinese made no effort at first to build a trainer version, similar to original MiG-21U describer in first Part of this story. In 1980s, however the decision was taken to design a Chinese trainer version and the task was entrusted to Giuzihou Aviation Industry Group Co (GAIGC). The resulting aircraft, designated JJ-7 fro home use and FT-7 for export, first flew in July 1985. It looks very like of Soviet MiG-21UM and US but differs in both major and minor ways. For example the very broad vertical tail is of Giuzihou design, and instead of having standard under-fin there are twin canted ventral strakes. The twin canopies opening to the right are quite unlike those of Soviet trainer versions being roomier (especially higher) and the dorsal fairing takes the form of removable saddleback fuel tank. External loads can include a 480 or 800-litre centreline tank, various missiles and rockets on the two under wing pylons and a type 23-3 twin barrel 23mm gun in package under the fuselage. Most of the avionics are western products and the instructor periscope is Chinese. Powered by the WP-7BM engine the FT-7 is cleared to higher weights than any Soviet MiG-21U version, the takeoff limit with PL-7 missiles and an 800-litre drop tank being 8.600kg. Further Chinese developments and projects are discussed in third part of this account. Meanwhile, back in Soviet Union it was known before the MiG-21F13 entered production that there would be further versions, and most immediate task was to rectify the omission of search radar to confer limited night & all-weather capability. Soviet industry was ready with the necessary radar, named “Spin Scan” and also known as R1L. This was to be the key feature of a new family of MiG-21 fighters, led off by the Ye-7 prototype flown 1959. It was the existence of this second generation that led the adaptation of MiG-21 by India. The IAF would never have bought the MiG-21F-13 except as an interim type leading on to a succession of more capable radar equipped versions. The same is probably true of Egypt. Nothing was known publicly of Ye-7 until Aviation day display at Tushino in August 1961, when two new MiG-21 were seen. One, 25 years later identified as the Ye-6V was a STOL version flown by Aleksandr Fedotov, fitted with two powerful solid fuel rocket bottles under the fuselage jettisoned after 10 second burn. The landing was shortened by a new cruciform brake shoot stowed in a tube immediately beneath the rudder. This was to become standard on future MiG-21 variants, the other new prototype was the first Ye-7, gaily painted along the leading edges of the wings and under the forward fuselage in form of giant red arrow-head. Unlike the rival Sukhoi bureau, which took long time deciding how to combine a nose inlet with radar the Mikoyan OKB had already solved the problem with such earlier research aircraft as the SM-12PM family. It was easy to design the optimum conical centre body to contain the main elements of radar, including the steer able centre fed antenna dish and then enlarge the nose of the MiG-21 to accommodate it. The lip diameter was increased from 690 to 910mm and it was soon clear that this increase in diameter would suffice for future installation of more powerful engines with increased airflow accommodated merely by reprofilling the internal centre body and duct. In fact the Mikoyan engineers did carry out a lot of refinement of the inlet on Ye-7 notably to perfect the way by which sluggish boundary-layer air is removed from the centre body. This air is sucked out through a peripheral slot forming the slight gap between the translating forward cone and the fixed rear section on which the radar is mounted. The depression to provide the suction comes from ducting the slit to after facing jets above and below the nose, the lower discharge being immediately ahead of the twin nose wheel doors, the duct downstream of the centre body was not altered. This provided with two pairs of doors in the walls. The auxiliary suck-in doors under the wing root were mentioned in Part one of this story. The other doors shaped like the door to a room and located well forward on each side of the nose, are closed in normal flight. They are hinged outwards from front and open against springs to allow air in the duct to spill overboard whenever supply exceeds demand. This is normally confined to Mach numbers greater then 1.5 (1.35 in later MiG-21 versions) whenever the engine is at any less then maximum rpm. A small detail is that the instrument boom on the nose was relocated above the nose. In its original “6 o’clock” position it had got in the way, often being damage and to prevent this it could fold upwards. Inevitably several aircraft “scrambled” with the boom folded, leading to loss of airspeed/yaw data which could be dangerous. Above the nose the boom did not need to fold and pilots also found it a useful guide to drift angle. A bigger modification was to improve the ability of MiG-21 to operate from short unpaved airstrip, surprisingly the more effective braking parachute moved above the rear fuselage, was not introduced until 1965, but an immediate change in all aircraft of Ye-7 family was to fit enlarged main wheels tires and brakes. The big 800mm tires rotated on the ends of legs through 87 degrees during retraction to lie in optimum angle inside the fuselage between the wing roots and the engine air ducts, but they projected much more obviously above and below the wing roots in big blisters. These tires enabled firm landings to be made with inflation pressure as low as 0.7 MPa though standard pressure in 0.785. This was roughly 25% lower then for the lighter MiG-21F13, and only one third of the pressure of the tires of an F-15E. Another of the major changes made in Ye-7 was to abandon the internal guns entirely. This was a difficult somewhat outright blunder (which was to show in future Middle East & Vietnam conflicts) and it left the totally inadequate armament of a pair of K-13 missiles or two rocket pods. The main reason was one of aircraft weight, by increasing the size of dorsal spine linking canopy and fin the main UKV and RS1U communication boxes were moved into spine, increasing internal fuel capacity to 2850 litres. In practice little more than 2000 litres could be used because of aft-movement of centre of gravity, so the extra weight could not be put to use. Almost the only advantage of removing of guns was that it enabled the airbrakes to be made simpler and more effective. Among minor changes in the Ye-7 was redesign of canopy to hinge up direct from the fuselage faired in at the rear by the enlarged forward part of spine, with no rear transparent area. Taken together with a bigger nose completely altered the appearance of the Ye-7 family. The new model became the Type 76, it was planned to be the MiG-21P (perekhvatchik – interceptor) but before the start of production the R11F2-300 engine became available at 5950kg afterburning thrust, resulting in the series aircraft being the MiG-21PF (F for Forsirovanni – boosted). Five years later, in 1965, this engine was up-rated to 6.175kg without reducing the overhaul life. The initial MiG-21PF reached Frontal Aviation regiments in 1963.
The initial PF-1 was succeeded on the production lines by PF-2 and PFV before the end of 1963. These had the relocated drag chute a further increase in fin chord modified tail end to the fuselage and entirely because of Indian pressure provision to carry GP-9 gun pack and much better wheel brakes. The GP-9 contained the excellent GSh-23L gun of 23mm calibre with twin rapid fire barrels and 200 rounds of ammunition, this made big difference to the fighting ability and further big plus was plumbing the wing pylons for tanks , doubling external fuel capacity. The PFV was a high altitude version one of its key features being the new R2L radar and SRO-2M IFF and Sirena passive radar warning receiver. All these aircraft were the Mikoyan Type 77 (MiG-21PF-13 “Fishbed D”), the export designation being MiG-21FL.
Back in 1961 the Mikoyan bureau flew the Ye-7SPS (SPS being the Russian abbreviation for blown flaps) and in 1963 this led to production of MiG-21PF-17 “Fishbed E” and MiG-21PFS “Fishbed E”. One more subtype was MiG-21PF-31 which precluded with PF-17 & PFS was MiG-21PF-31 “Fishbed E” included further extension to fin chord, but original un-blown flaps with provision for GP-9 pack.
The flaps were no longer track mounted but were just hinged and of slightly increase chord. High pressure bleed air from the engine is blasted at supersonic speed through a narrow slit just above and ahead of the flap to keep airflow attached with the flaps down to greatly enhanced lift. Externally the SPS and its subtypes MiG-21s can be identified by the big blister fairing over the mid-span flap actuators. The engine with bleed connections became the R11F2S-300. the SPS and some un-blown late PF-2s (MiG-21PF-31s) introduced yet a third increase in fin chord - as mentioned, coupled with an increase in size of aft-pointing fin tip above rudder to give more room to antennae and lights. At about 1966 a new variant was put in service named MiG-21PFM “Fishbed F” which included all the major and minor changes of earlier PF-1/PF-2 models in one (including the SPS & third fin chord increase) and also some new equipment as redesigned cockpit canopy hinging to starboard with conventional windscreen. Problems with older ejection seats led to introduction of KM-1 zero/zero ejection seats which was to save life of many pilots in future and ongoing conflicts (Middle East & Vietnam) the most important item of MiG-21PFM was an upgraded R2L radar “Spin Scan B” (mainly maintenance improvement).
While the Mikoyan OKB continued mainstream development in a succession of mostly fairly minor changes will be described in 3rd Part, an interesting succession of projects & experimental MiG-21s also appeared. One of these was Mikoyan’s response to widespread interest in jet-lift V/STOL aircraft in early 1960s. the MiG-21DPD (DPD, Russian for supplementary lifting engines) also known as Type 92 was basically a total rebuild of a MiG-21PFM for research into jet lift with an aircraft theoretically capable Mach 2. The airframe was modified as little as possible the wings and tail being left almost in their original state. The fuselage however was lengthened by 1.2m at the center of gravity by splicing in an extra bay to house twp special lift turbojets usually described as Koliesov Type ZM each rated at 3.500kg. These were tightly fitted into a bay between the engine inlet ducts which curved round this bay in a specially bulged centre fuselage. Above the lift jets was an inlet door with multiple louvers hinged up at rear while below the nozzle was a panel of pilot controlled cascade vanes to control the jet angle of pure lift, braking or acceleration. Bleed–air control jets were added at nose and tail to control pitch at speeds down to minimum level of 100km/h. the landing gears were fixed, an extra dorsal fin was added and the cockpit was that of later MiG-21 versions described in next instalment. An even more striking rebuild was the Ye-8 series. In the late 1950s the Mikoyan OKB studied various arrangements of lateral ventral and even dorsal inlet in order to fit larger multimode radar into the nose. Eventually a MiG-21 with a ventral inlet was drawn which looked so good that OKB got permission to built it, as Ye-8. A further feature of this aircraft was a fully controllable powered canard fore plane, fitted with projecting flutter-damping weights projecting ahead at midspan (on the horizontal tails they are at the tips). These canard surfaces were first tested on a hack Ye-6T, possibly the first aircraft in 40 years to have horizontal control surfaces on both ends. The modified Ye-6T gave encouraging results even though the canard was at same level as wing. The Ye-8 canard was at higher level, it is believed two Ye-8 s were built one being fitted with the prototype J-Band radar later adopted for MiG-23. Flight testing of two of these aircraft began in 1962 and it is reported that due to total engine failure Georgii Mossolov nearly lost his life in one. It has being suggested unofficially that the other Ye-8 provided data to assist the design of Sukhoi T-100/101 supersonic bomber. Mikoyan used the basic aerodynamic shape of the MiG-21to design several larger aircraft to meet other Soviet air force requirements. Some of the ones that flew are listed. The I-370 was a swept wing fighter bomber based on Ye-2 aerodynamics as was the I-380. The later was built as the I-3U fighter bomber and I-3P interceptor, but these were beaten in evaluation by the aircraft which became Su-7 “Fitter” and Su-9 “Fishpot” respectively. The I-75F was related prototype with a Lyulka engine, Uragon Radar and AA-3 “Anab” missiles. Several large scale deltas were flown, the first being the Ye-150, this 1958 prototype was basically a scaled-up Ye-6 with 9500kg Tumanskii R-15 engine and K-8 and K-9 missiles. The Ye-152 of 1959 had a 10200kg R-15A engine, minor airframe modification and a new integrated navigation and Interception system. The Ye-152A”Flipper” featured a redesigned fuselage to accommodate two R-11 engines side by side. A Chinese copy was built as the Shenyang J-8 “Finback”. The Ye-166 was a development aircraft for the engine intended for MiG-25. It featured a new tail and streamlined fuselage and the canopy. It was to etablish a world speed record of 2.681km/h in 1961 and a sustained altitude record of 22.670m in 1962.
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