By a decree of the Council of Ministers of the USSR of June 3, 1953 (the corresponding order of the Ministry of Aviation Industry was issued on June 8), OKB-155 was instructed to design and build an experienced front-line fighter I-3 (I-380) for a new powerful VK-3 engine, which was created at OKB V. Ya. Klimova since 1949. It was intended for installation on new Soviet interceptors, designed for a maximum flight speed of about 2000 km / h, and practically became the USSR's first two-circuit turbojet engine with an afterburner. The first prototype of the aircraft, armed with three HP-30 cannons, was required to be presented at state tests in the first quarter of 1956. According to the draft design, approved in March 1954, the maximum speed of the I-3 (I-380) on afterburner with a takeoff weight of 8954 kg could reach 1274 km / h at the ground, and 1775 km / h at an altitude of 10,000 m. The calculations were carried out on the condition that the VK-3 engine will have a thrust at the nominal operating mode of 5160 kg, at the maximum mode - 6250 kg, at the afterburner - 8400 kg.
The range and duration of the flight could be increased by installing two standard outboard tanks with a capacity of 760 liters under the wing. It was envisaged to arm the cockpit: front armored glass with a thickness of 65 mm, front armored plate (12 mm), armored headrest (16 mm) and armored back (16 mm). The total estimated weight of the armor was 87.5 kg. The aircraft's armament consisted of three fixed wing guns HP-30 with a total ammunition of 195 rounds (the capacity of the ammunition boxes made it possible to place up to 270 pieces). Aiming was carried out with an ASP-5N optical sight combined with a Radal-M radio range finder. In the overload in the fuselage, a retractable installation for firing unguided ARS-57 projectiles could be installed (their stock was 16 pieces). Instead of hanging tanks, it was possible to install two large-caliber shells of the TRS-190 or ARS-212 type, as well as two 250-kilogram bombs. An experienced I-3 was built, but it was not lifted into the air due to the unavailability of the engine. However, many of the elements and design solutions worked out on it were embodied in the following OKB-155 aircraft.
The next series of prototypes, created as part of the work on the front-line fighter had the code "E". There is an opinion that the aircraft of the "E" series began to be developed under the "X" index, starting with the X-1. However, no confirmation of this was found in the reports of the pilot plant No. 155 and in the correspondence of OKB-155 with the customer and the ministry; the only thing that came to light was the X-5 project. Let me assume that this was the only project with such a designation, and the number 5 is nothing more than engine thrust in tons. Apparently, someone was confused by the designation "X", characteristic of American experimental aircraft. "X" is denoted in the transcription as "eks"; it is quite possible that this explains the choice of the letter "E" to designate promising machines OKB-155.
Aircraft of the "E" family began to be created in accordance with the decree of the Council of Ministers of the USSR dated September 9, 1953 (on the same day a decree was issued on the creation of the AM-11 turbojet engine) and the order of the Ministry of Aviation Industry of September 11 "On the creation of a front-line fighter with a delta wing design, etc. Mikoyan ", which, in particular, said:
“In order to further improve flight technical data and master a new fighter scheme, the Council of Ministers of the USSR by the Decree of September 9, 1953:
1. Obliged the IAP (vol. Dementyev) and Chief Designer Comrade Mikoyan to design and build a single-seat front-line fighter with a delta wing, with one AM-11 turbojet engine designed by Comrade Mikulin with a thrust of 5000 kgf with afterburning ….
The document prescribed that the maximum speed during operation of the turbojet engine in afterburner mode for five minutes was not lower than 1750 km / h at an altitude of 10,000 m, the climb time to this altitude was 1.2 minutes, the practical ceiling was 18000-19000 m. The range was set at least 1800 and 2700 km when flying at an altitude of 15000 m without using afterburning in a turbojet engine, and the takeoff and run length is no more than 400 and 700 m.
The aircraft was supposed to allow a steady vertical dive with the use of brake flaps from all flight altitudes and a turn in this mode. It was required to ensure the possibility of operating the fighter from unpaved airfields.
On the plane, it was required to install three NR-30 cannons, an optical sight coupled with a radio range finder; in addition, the vehicle was supposed to carry 16 ARS-57 rockets. There was no talk of bomb armament yet. The first copy of the planned two prototypes was required to be presented for state tests in March 1955, i.e. less than a year after the order was issued.
However, the engine intended for the new aircraft did not mature in time, and besides, the chief designer of OKB-ZOO was soon replaced. As a result, it was necessary to install a less powerful AM-9 engine, which was, of course, an annoying circumstance, but not critical, because even with the old engine it was possible to study the behavior of the machine in flight and then refine the design.
The designers had no doubts about the engine chosen for the promising machine; controversy erupted over the determination of the shape of the wing. The triangular wing specified in the decree, although considered very promising, at the same time, concealed many unknowns and had a high design risk. The general designer decided to play it safe by starting work in two directions - arrow-shaped and triangular.
Judging by the assignment, the vehicle was intended to combat low-maneuverable targets - bombers, since neither the rate of fire nor the ammunition load of the guns planned to be installed on the aircraft made it possible to effectively combat enemy fighters. It seems that the experience of the war in Korea has taught nothing to the "trendsetter" - the domestic Air Force. Or maybe someone "above" saw the main threat in bombers. One way or another, the OKB-155 provided for the installation of only two guns on the fighter.
Until July 1954, the designation X-5 can still be found in the documents of the aviation industry, but already in August there is a mention of the project of the E-1 aircraft, set by the Council of Ministers decree of September 9, 1953, albeit with the AM-9B engine, which was used on MiG-19 aircraft. However, the E-1, designed with a delta wing, never got out of the project stage. The reason was due to the difficulties in the development and research of the delta wing. A similar delay took place at the P. O. Sukhoi when creating the T-3 fighter. For this reason, it was proposed in the first place to develop an aircraft with a swept wing. So the E-2 became the progenitor of the new family of aircraft.
In February 1955, by order of the Minister of Aviation Industry, test pilot G. K. Mosolov (understudy V. A. Nefedov) and engineer A. S. Izotova.
The first flight of the E-2 took place on February 14, 1954. The aircraft was equipped with a 57 ° swept wing along the leading edge and a relative thickness of 6%. To improve takeoff and landing characteristics, slotted flaps and two-section slats were used. Roll control was carried out by two-section ailerons. Subsequently, to eliminate the reverse of the ailerons, which occurred in some flight modes, spoilers were installed on the wing. The leading edges of the shells of the frontal air intake device (VCU), by analogy with subsonic machines, were made semicircular, which created an additional suction force.
The press repeatedly mentions that a speed of 1950 km / h was reached on an airplane with an RD-9B engine. This is a deep misconception. Apparently, this speed is calculated for the aircraft with the AM-11 turbojet engine and is taken from the assignment for this aircraft. And elementary calculations show the impossibility of achieving such a speed. So that the reader has no doubts, I will give an example: the SM-12/3 aircraft, having approximately the same flight mass and twice the thrust-to-weight ratio, developed a maximum speed of 1930 km / h. In January 1956, the first E-2A / 1 aircraft was handed over to factory tests (in 1957, someone at the GAKT or OKB assigned it the designation MiG-23) with the R11-300 turbojet engine. Converted from E-2, the plane stood for exactly one year, waiting for the engine. A distinctive feature of this machine was the aerodynamic partitions (ridges) on the wing, which were absent from its predecessor. The first flight on this machine was performed by the test pilot of the OKB G. A. Sedov February 17, 1956 A. S. Izotov.
The tests of the E-2A were very difficult. The machine was characterized by longitudinal swing caused by defects in the layout of the control system, increased sensitivity to small deviations of the control stick in roll at high indicated speeds. It took a lot of time to eliminate the defects of the power plant, which is why the car was in a non-flying state for 11 months. In addition, it was necessary to deal with the shaking detected during high speed flight at low altitudes, and with lateral swing.
Six months later, the second E-2A / 2 aircraft arrived from plant number 21, which on the last day of December OKB-155 presented to the Air Force Research Institute for state tests. In 1956-1957, 107 flights were performed on this aircraft (at least 165 flights on both aircraft), which made it possible to remove all the main characteristics. Industrial pilots V. A. Nefedov and A. P. Bogorodsky. After the engine and equipment had reached their end of life, the planes were decommissioned as unnecessary. During tests on the E-2A with a flight weight of 6250 kg, the following indicators were achieved: maximum speed 1950 km / h (M = 1.78), ceiling - 18000 m, time to climb 10000 m - 1.3 minutes, range - 2000 km. The armament consisted of two NR-30 cannons and two jet guns suspended under the wing with ARS-57 unguided aircraft missiles. The ASP-5N sight was used for firing. Bomb armament was also envisaged.
The third type of aircraft of the "E" series was the E-4 with a delta wing, which, before the release of the government document, was being developed, as noted above, under the designation X-5. In April 1954, the draft was defended.
As in the cases with the E-2 and E-50, instead of the standard P11-300, the RD-9 engine had to be installed on the plane, and the start of flight tests with a standard turbojet engine was postponed from March 1955 to August 1956. This was done to speed up the tests and determining the flight characteristics of the future E-5. On June 9, 1955, by order of the GKAT on the E-4, they appointed pilot G. A. Sedov (understudy V. A. Nefedov) and engineer V. A. Mikoyan. A week later, Grigory Alexandrovich performed the first flight on the E-4.
Initially, the plane, like the T-3, had a clean wing, recruited from TsAGI-S9s profiles, but with aerodynamic partitions - one each on the lower surfaces of the consoles, approximately in the middle. Apparently, TsAGI still poorly represented the true picture of the flow around the delta wings, so they moved forward by the method of "trial and error". The E-4 actually became a flying laboratory, where the influence of various ridges on the aerodynamic characteristics of the wing was investigated (the research was continued on the E-5). During the tests, the aircraft reached a maximum speed of only 1290 km / h. In 1956-1957, 107 flights were performed on the E-4, having fully exhausted the resource of the engine and equipment.
On January 9, 1956, test pilot Nefedov made the first flight on the next prototype with a delta wing, the E-5 aircraft with the P11-300 turbojet engine - an aircraft that received the designation MiG-21 a year later. V. Mikoyan remained the leading engineer for the car. Apparently, Dementyev and Mikoyan reported to Khrushchev on April 2, 1956 that the speed of 1810 km / h at an altitude of 10,500 m was reached on March 30, and the Central Committee of the CPSU and the government attached great importance to this. But this value turned out to be not the limit: on May 19, in flight at an altitude of 11,000 m, the speed reached 1960 km / h, which corresponded to the number M = 1.85.
Thus, the test results puzzled even the most experienced, the most experienced: the delta wing did not bring any big advantages, an obvious gain, and the question involuntarily arose, is it worth building a garden trying to master this wing? The leaders of the design bureau gathered in Mikoyan's office. The chief designer gave the first word to the testers. However, for the pilots, there is no doubt so far not much - the delta-wing aircraft accelerated a little faster and, due to the larger fuel supply, had a slightly longer range.
Even having built and at the same time tested aircraft with different wings, it was not possible to make a decision immediately. Artyom Ivanovich came to watch the flights of both aircraft more than once, talked with pilots, engineers, delved into all the little things. Any of these little things could tip the scales in one direction or another.
At the same time, the designers studied the situation in world aviation, analyzed the materials of the aviation press, identifying a trend, the main direction of development.
The Americans advertised the F-104 Starfighter with a deafening noise. Its chief designer - Clarence Johnson of Lockheed, the creator of the infamous U2 spy plane - chose for the Starfighter a seemingly completely expelled from high-speed aviation, a straight trapezoidal wing of a very small area, and an aspect ratio of only 2.45, with an extremely thin profile and pointed leading edge (radius of rounding of the toe 0, 041 cm). Such a wing has extremely low lift. To provide more or less acceptable take-off and landing characteristics, Johnson equipped the aircraft with tiltable wing tips throughout the span and large slotted flaps with a large chord. Around the same time, the third high-speed fighter, the development of which was widely discussed in specialized magazines - "Mirage" with a triangular, like that of the future MiG, wing - the French designer Marcel Dassault began to develop. So who's right? The Americans or Dassault, whose position coincided with that of Mikoyan?
Having investigated the capabilities of an aircraft with a straight wing, Mikoyan did not believe in its prospects. The choice remained only between the swept and delta wing. The final choice between them in favor of the latter was made by the customer. Summarizing the test results, they began to build the last prototype of the future MiG21. This pre-production car was called E6. And the E-2 remained in the category of experimental ones, since the serial plant in Gorky built only seven E-2A aircraft.
List of used literature:
Mikhail Arlazorov "This ageless MiG-21"
Efim Gordon "Non-standard MiGs"
Nikolay Yakubovich. The birth of a legend
The history of aircraft designs in the USSR 1951-1965
Efim Gordon. The birth of a long-liver
Rostislav Vinogradov, Alexander Ponomarev "Development of World Aircraft"
