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MiG-21, Part 1

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MiG-21, Part 1
By Khan Syed Shaiz Ali
Oct 7, 2003, 18:31

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By almost every account the MiG-21 is the most famous and most widespread jet fighter on the world.

This might appear rather odd, because when one studies any MiG-21 it appears rather limited aircraft, described by a senior pilot in one of its user air forces as a "supersonic sports car". Yet, the fame of the "Twentyone" rests on several unchallengeable facts: it has been manufactured in greater numbers then any other fighter since World War II; it has been made in more versions then any other fighter since World War II (and new versions are still appearing!); it has had the longest active life of any warplane in history, and has many years still to go; it has been involved in more wars in more parts of the world then any other fighter in the history; and it has served with more air forces then any other jet fighter. In fact, hardly any other aircraft can beat the MiG-21 when it comes to the number of air forces which operated - or still operate - it.

Where the MiG-21-story will end cannot yet be predicted, though we will take a look at a current situation later through this long story. But the beginning can be traced clearly to a 1953 specification for a new fighter issued by NII VVS, the scientific research institute of Soviet Air Force. Three years of Air Combat over North Korea had clearly shown the need for a new fighter having highest possible performance. In the USA, Lockheed's Clarence L. "Kelly" Johnson had even gone to Korea to find out what fighter pilots wanted, and came back convinced they wanted speed, climb and height at the expense of everything else, resulting in the F-104 that in turn proved far too inflexible and would have been almost a failure had not Lockheed pressed on and developed it into a very fast low-level attack and reconnaissance aircraft, as the R/F-104G.
The Mikoyan design team in Moscow was given a very similar set of demands, and they came up with a very similar answer, in a small highly supersonic aircraft powered by a single afterburning turbojet. This fighter was not to carry heavy loads of fuel, electronics or weapons, as the V-VS required the new fighter to act purely in a defensive role, shooting down fighters and such Bombers as the B-47, B-52, and the B-58. The B-58 was by far the most difficult adversary, because of its great range and Mach 2 speed. Reluctantly it was accepted that new fighter could not do everything: if it was going to set new standards in steepness and rate of climb, in operating altitudes, Mach number (over 2) and manoeuvrability at all speeds. So the requirement called for point defence in daylight, operating under close ground control and attacking with guns only.
The Mikoyan design bureau was already overloaded with numerous prototypes and research aircraft, most of them related to MiG-17 or MiG-19 families. The latest aircraft in both families were powered by paired axial turbojets of RD-9 type, developed by S. K. Tumanskii of A. A. Mikulin's design bureau. In 1956 Mikulin was removed and Tumanskii began his career which has today made him number 1 engine designer ( certainly on the score of numbers of engine built), with a near monopoly position in powering Mikoyan aircraft. Whereas the RD-9 was single shaft engine, typically rated at 3250 kg with maximum afterburner, Tumanskii began testing a new engine in late 1954 with similar simple design but with two shafts. Designated R-11 in 1956, this engine had only three stages on its LP compressor and three more in HP spool, the thrust being 3900 kg dry and 5100 kg with full afterburner. This new engine was well matched to the new fighter, enabling it to be single-engine.

What was by no means certain was what type of wing should be used. The TsAGI, the national aerodynamic institute, had carried out exhaustive test of various configurations and could not decide between a covenantal swept wing, again with leading edge sweep angle of 57 or 58 degrees and a perfectly triangular ( so called ?Delta?) wing, again with the leading edge swept back at 57 degrees. For minimum drag it was considered preferable to mount the wing at 90 degree to the fuselage side just below the mid position, resulting in slight ahedral. What was never in doubt was that the wing should have outboard ailerons and high lift inboard flaps, latter demanding the use of horizontal tail.

At this time Mikoyan OKB prototypes were numbered in a Ye (yedinitsa = single unit) sequence, though the Cyrillic character Ye looks Like E. Permission was given for the OKB to build prototypes with both types of wing, the aircraft being otherwise similar as possible. The aircraft were designated Ye-2 (swept) and Ye-4 (Delta), the construction went ahead quickly so that both were ready long before the R-11 engine. Accordingly, both were redesigned on the drawing board to take a single RD-9Ye, rated only 3250 kg Max. This precluded the attainment of the hoped for Mach 2 performance, but sufficed to show which aircraft was preferable (it was confidently expected the Ye-4 would be faster, and it would be superior in manoeuvrability). Chief test pilot. G. A. Sedov was assigned to the Ye-4 and all Mikoyan deltas, while Ye-2 and other swept wing prototypes were assigned to Georgii K. Mosolov, V. P. Vasin and V. A. Neyfyedov.

There is no doubt the Ye-2 flew first. it seems certain that the first flight date was 14 Feb 1954, but a 1986 article by the authoritative engineer V. Kondratyev gives the date as 14 Feb 1953, and underscores this by commenting that no delta flew until two years later. This is hard to understand; other historians state that the Ye-2 flew in Feb 1955 and Ye-4 four months later, in June, and this accords well with other evidence. Mikoyan was also given permission to build third aircraft, based on a Ye-2 airframe, boosted by a rocket engine. Many Soviet design bureaus had gained experience with liquid-propellant rockets added to boost the speed of piston engine fighters and the technique was thus quite familiar. Mikoyan was concerned that the thrust of the small interim RD-9Ye would prevent meaningful comparisons made and so the third aircraft was ordered as Ye-50. It was almost identical to Ye-2 except for having a ZhRD S-155 rocket engine pump-fed with kerosene from main tanks and with RFNA (red fuming nitric acid) from a specially protected extra tank. The thrust chamber and control system were neatly grouped in slight bulge in the rear of the fin root under the rudder.

Three Prototypes
It has been reported that a batch of 12 Ye-50A interceptors was built, but in fact there were only three experimental prototypes. Valentin Moukhin flew the first in June 1955. Some time later the turbojet flamed out on the approach and Moukhin was slightly injured in the resulting crash short of the runway.

While he was recuperating V. P. Vasin was assigned the test pilot of the Ye-50/2, which was virtually identical. On 17th June 1957 this aircraft reached Mach 2.33 in level flight, and on another occasion Vasin reached the sustained height of 25,600m. Normally the rocket was activated at 9000m, but in winter 1957 Vasin lit it on takeoff to impress Marshall Zhukov. Vasin was made Hero of Soviet Union for the Ye-50 project which concluded in 1958 with Ye-50/3 fitted with unspecified changes to the nose, rear fuselage and vertical tail. The Ye-60 - described later - was related.

By early 1956 the R-11S engine was at last becoming available and this was fitted to Ye-2A flown by Grigorii Sedov on 22 March 1956. Like the Ye-2, it had a swept wing resembling a smaller version of that in production for the MiG-19, two large ventral fins inclined at 45 degrees under the rear fuselage, two NR-30 guns (the Ye-50 had three) and a novel one piece Plexiglas canopy which hinged up at the front. The rear of the canopy was pivoted to the top of the ejection seat so that if pilot ejected the canopy served as a windbreak in front to protect him. The nose and engine duct looked like that of Ye-2 despite the increase in airflow. The two obvious differences were that the Ye-2A had a gigantic fence at mid span of each wing aligned with inboard ends of the ailerons and projecting ram-air cooling inlets on the sides of the rear fuselage faired in to the roots of the tail planes. It also had redesigned and enlarged rear fuselage. Maximum speed of Ye-2A was 1900km/hr or Mach 1.79.

The Mikoyan OKB at last got a delta technology demonstrator in to air on 16 June 1956 when Grigorii Sedov flew the Ye-4 /1. Apart from wing this aircraft was virtually a Ye-2 still with RD-9Ye engine. This naturally made it impossible to exceed 2000 km/h as had being hoped but in fact the performance was worse then expected, maximum speed being slower the MiG-19 production versions. Prolonged tinkering took place with the Ye-4/1 and with the Ye-4/2 flown a few weeks later in an endeavor to discover the cause. The Ye-4/2 differed chiefly in having clipped wingtips and three fences on each wing. the height and geometry of fences being modified at least four times. Eventually well into 1957, the main drag problem was traced in to rear fuselage and especially to the area around jet nozzle. This was also found reducing speeds reached by the Ye-2 series.

Western Debate
On 24th June 1956 the Ye-2A and Ye-4/1 both made high-speed fly-pasts at the aviation day show at Tushino. Western photography was abysmal, and for the six years Western analysts argued over who had designed these fighters, what they were called, and which if any was going into production. To make things worse Sukhoi's resurrected OKB also flown a swept-wing and delta-winged aircraft looking very like MiGs - but larger. Western writers soon learned that NATO had assigned the reporting names Faceplate, Fishpot, Fishbed and Fitter, but the confusion was indescribable and made more worse by supposed Soviet designations concocted in the fertile brains of Western writers. As late as 1963 authoritative Western books stated that the production MiG-21 (Often incorrectly written Mig) was a swept wing "Faceplate": several publications that came out in different Communist countries at the time only increased the chaos, as it appears that in most of them the MiG-21 was purposely mixed with the Su-7.

At an unknown date around September 1958 one of the Ye-4s was re-engined with R-11S, rated at 5100kg, becoming the Ye-5. Soviet engineers insist this was not a new aircraft though its wing had tips of Ye-4/1 and the fences of Ye-4/2 in their final form. This aircraft at last touched "2000km/h" and also showed itself slightly superior to Ye-2A in manoeuvrability, climb and internal fuel capacity. Therefore, though it was a close run thing, Mikoyan and NII VVS picked delta over the traditional wing in early 1957. In some documents the Ye-5 is called I-500 and Mikoyan OKB had several other prototypes at this time with "istrebitel" (Fighter) designations all much bigger then Ye-2A and Ye-5. These were members of different families as were a series of SM-12 prototypes which looked very like Ye-2As but were actually derived from MiG-19 Family.

The Mikoyan bureau was busy in 1957 building a number of refined aircraft, designated Ye-6, incorporating everything previously learned. All had 57 degree Delta wing and R-11 engine but the details varied. The Ye-6/1 had very slightly clipped tips and the same fence as Ye-5, the two inboard fences wrapping around the leading edge and the outer being much smaller and entirely on the upper surface. Other changes included a slight lowering of the position of the wing and horizontal tail which necessitated redesign of the airbrakes in to three separate surfaces and replacement of the inclined ventral fins by single fin on the ventral centreline. More fundamentally the Ye-6 was form the start not a research and demonstration aircraft but a prototype of a fighter in the form that was to enter production. Guns were two NR-30s and the engine R-11S of 5100kg thrust.
One of the Ye-50s was retrofitted with the powerful R-11F-300 engine with fully variable afterburner and a new nozzle giving thrust of 5750kg. Together with rocket this resulted in the remarkable speed of 2640km/h with Mach 2.6 (2766 km/h) calculated to be attainable. this aircraft, which was also known as Ye-60, was distinguished by a very large scabbed-on belly tank along most of the length of fuselage to boost rocket endurance.

Engine Explosion
The pilot assigned to Ye-6/1 was Nyefyedov. Early testing was encouraging and the speed of Mach 2.05 achieved at a height of 12km. Unfortunately, on 28 may 1958 the engine exploded at the height of 18km, seriously damaging the flight controls (another report claims merely that the engine suffered compressor stall and flameout, Nyefyedov failing to relight because the starting gasoline tank was over heated and contained vapour only). On the approach Nyefedov was progressively losing control and finally the aircraft crashed, killing the pilot.

Tail-pipe of the TUmanskiy R-11F-300 engine that was powering the early MiG-21F-13s. (via Tom Cooper)

Under pressure the flight controls were redesigned. Flight development of this task was in the hands of Mossolov, while the engineer whose proposals were accepted by Mikoyan was Rostislav A. Belyakov (later to become General Constructor in the Mikoyan OKB). He argued the case for total duplication everywhere, from hydraulic pumps to the surface power units. Many other improvement were made in 1958 including a three position inlet centre-body, housing simple ranging radar, the forward cone being pushed fully forward at Mach 1.8 or above, and auxiliary engine inlet doors under the wing root leading edges.

Other details common to all Ye-6 aircraft were that the transparent upper decking behind the cockpit at front of spine was replaced by a separate window on each side the braking parachute (of traditional multi ring type) was housed in a box just above the left side of the front of the ventral fin the wing tips were clipped and the armament comprised of two NR-30s. In the Ye-6/2 flown at about the time Ye-6/1 was lost the multiple fences were replaced by small single fences over the rear wing only in line with the narrow fixed strip between ailerons and the flaps. The later resembled the track mounted Fowler type but lacked any fixed surface above; they were depressed to 24.5 degrees for takeoff and 44.5 degrees for landing, the leading edges were fixed. The Ye-6/3 was in virtually all respects the production aircraft. Flown in December 1958 , it led straight into a series of 30 production aircraft designated MiG-21F delivered from designated production plant ( all previous aircraft having been made at the Mikoyan OKB) in early 1959.

Intake with the nose-cone of the MiG-21F-13. The plane lacked radar at the time, instead having a simple SRD-5 range-finder in the nose, which wsa feeding the ASP-5ND gunshight. (via Tom Cooper)

On 31 Oct 1959 the Ye-6/3 (reported to FAI as the Ye-66) gained the Soviet Union's first speed record flown by Mossolov over the 15/25km course at an average of 2388km/h. the aircraft engine was reported to FAI as R37F. A year later K. Kokkinaki used the Ye-66 to set a 100km circuit record at 2149km/h, while on 28 Apr 1961, Mossolov used the Ye-66A, believed to have begun life as the same aircraft to set an altitude record of 34714m. The Ye-66A was powered by an R-11F2S-300 rated at 5950kg plus a bolted on U-2 rocket in the ventral package complete with RFNA tank, the thrust chamber being under the rear fuselage.

While this was going on the production factory was building up output of the first true series version - the MiG-21F-13. This was the finalized version of Ye-6T, with T allegedly standing for ?trophy?, meaning the capture of AIM-9B Sidewinder missile by Chinese fighter in which it had lodged without exploding, thus referring to the new armament that comprised a pair of copies of this missile, designated in the Soviet Union as K-13.

Egypt was one of the earliest export customers for the MiG-21F-13 outside the Warsaw Pact, getting its first 40 examples - the MiG-21F-13 serialled "5001" was the very first 21 ever delivered to Egypt - starting in late 1962. By 1964 a total of 60 were in service, but due to a series of technical problems there were only two operational units equipped with them. (artwork by Tom Cooper)

The first MiG-21F-13 delivered to Yugoslavia, in 1962. At the times the delivery of MiGs to Yugoslavia was a considerable surprise, then for the ten proceeding years there were severe tensions between Belgrade and Moscow, with the USSR threatening to invade in 1949 and 1950, and consequently the Yugoslavs requesting help in the West, which resulted with deliveries of F-84G Thunderjets and F-86 Sabres. (Tom Cooper collection)

Algeria was a relatively late customer for the MiG-21, purchasing the first batch of some 30 F-13s only in the time between 1965 and 1966. (artwork by Tom Cooper)

Later there were to be many variations on the K-13 whose output was even to exceed that of US prototype. The two missiles were hung on simple underwing pylons fitted with the electrical and refrigeration connections. Otherwise, the available payload was so limited that adding the missiles required deletion of left hand NR-30 gun, fed by a box containing 75 rounds.
The opportunity was also taken to increase chord (width) of the fin to improve yaw stability - especially at high AoA (subsequent MiG-21 versions would take this process very much further). Many thousands of MiG-21F-13s were made, including aircraft designated S-106, made at Prague Vodochody, in then Czechoslovakia, starting from 9 May 1963, and usually distinguished by having a metal instead of transparent area in the spine immediately aft of the canopy. Many others were made without license in People's Republic of China, named J-7.

India has got its first small batch of MiG-21F-13s in 1963, and the early service of the type with the IAF was marred with technical problems (especially with spare parts and weapons) and accidents. The Indians also heavily complained about the Soviets training their original MiG-21-pilot in a very rigid, repetitive, and rather boring manner, not permitting them to fly into clouds nor only on instruments. (artwork by Tom Cooper)

Further Prototypes
There were several other Ye-6 prototypes. One of the most important became Ye-6U, first flown in 1961, and with its internal fuel capacity reduced from 2470 to 2400 liters. The U had no provision for armament, instead getting tandem cockpits equipped with the completely new KM-1 ejection seat and side-opening canopies. When the MiG-21U entered production it was equipped to carry a 490 litre ventral tank. A related aircraft was reported to FAI as the Ye-33, used by various lady pilots, lead by Natalya Prokhanova, who set a height record of 24366m.