Ye-150 / Ye-151 / Ye-152 - Flipper

At the 1961 Tushino show, an aircraft was introduced which appeared to be an enlarged MiG-21 which mounted two engines and large air-to-air missiles. It was designated Flipper in the West while the Mikoyan designation is thought to be I-75F. Four months later, the Soviets claimed a world speed record of 1,492 mph for an aircraft designated the Ye-166. However, the record setting aircraft was claimed to have but one engine.

Not until the Ye-166 was displayed in 1967 did it become evident in the West that it and the two-engine Flipper were single and twin-engine versions of the same basic design. Conjecture was that the Flipper was abandoned because the missiles proved too difficult to develop or that the size of the supporting radome justified a change of design approach toward jet inlets on the side of the fuselage. It is also possible that the exploitation of U.S. Sidewinder technology in the Atoll missile allowed the Flipper mission requirement to be satisfied by a modification of the MiG-21.

The initial missile armed version, designated Ye-150, flew for the first time on 8 July 1960, after extensive ground checks of systems and a delay in delivery of a flightworthy engine. Flight tests progressed slowly, hampered by the very short life of the R-15 engine, (barely sufficient for pre-flight ground checks and a single flight), as well as problems with aileron buffeting, brake parachute failure and the engine accessory gearbox disintegrating. Manufacturers flight tests, over 42 flights, revealed very high rates of climb, impressive maximum speed (M2.65 @ 19,100m (62,664 ft) using less than full throttle), and a phenomenal service ceiling of at least 21,000m (68,900 ft). Installation of weapons systems was not carried out on the Ye-150 and it was not authorised for production, but development continued with the Ye-151, and Ye-152.

The Ye-151 cannon armed version was designed in parallel with the Ye-150 but did not proceed to the hardware stage. The weapon system was to have consisted of twin TKB-495 or Makarov TKB-539 cannon, with a rate of fire of 2,000 rds/min, mounted on a rotating ring in tilting mounts. The mounts could tilt ±30° and the mounting ring could rotate 360°, which gave the installation a 60° cone of fire around the centreline of the mounting ring.

The two single engined Ye-152's were completed with improved R-15-300 engines, as the Ye-152-1 and Ye-152-2, but reliability remained an issue, with only limited development flying, weapons system testing and world record flights carried out. The poor reliability of the engine and the cancellation of the intended K-9 / Urugan-5B weapon system brought the Ye-152 program to a close.

To fulfil the needs of the PVO (Protivovozdushnaya Oborona – air defence forces) for a heavy interceptor to carry out automatic interceptions, Soviet heavy interceptors included the Lavochkin La-250, MiG I-3, I-7, I-75, Ye-150/151/152, Sukhoi T-37, P-37 and Tupolev Tu-28/128. The MiG bureau developed a range of large fighter aircraft starting with the swept wing I-3 series (a.k.a. I-380, I-410 and I-420), followed by the I-7 and the I-75. The requirement for supersonic interception speed and the ability to carry the heavy avionic systems dictated the size; in comparison the contemporary MiG-21F (similar in layout), weighed 4,819 kg (10,624 lb) and was 15.76m (51 ft 8-1/2in) long, compared with 12,345 kg (27,215 lb) and 18.14m (59 ft 6in) respectively, for the Ye-150.

The MAP (Ministerstvo Aviatsionnoy Promyshlennosti - ministry of aviation industry) ordered the Mikoyan OKB to build prototypes of the new interceptor, to be armed with either K-6, K-7, K-8, K-9, unguided rockets, or an aimable twin cannon installation. Automatic guidance to the interception point was to be provided by Urugan-5 (hurricane-5) integrated weapons systems.

The new all-weather fighter-interceptor E-150, planned in KB Mikoyan, had to develop a speed exceeding three times the speed of sound. Therefore before its creation "in the metal" it was necessary to solve the problem of the thermal barrier - to develop and to create more resistant materials, capable of maintaining flight loads at increased temperatures. The usual aluminum alloys simply "flowed" under these conditions. In connection with the high aerodynamic heating of aircraft at the high speeds, the most heat-stressed elements of construction had to be carried out from the thermoresistant materials (for example, made of the stainless steel). It was necessary to learn to make the construction of aircraft from high-temperature steels, titanium alloys and composites, to develop the technology of series production, and it was neccessary to solve these problems within the shortest period of time.

In the summer of 1957 the draft designing of the E-150 interceptor was completed - the first of the "heavy MiGs" - and the directive of the administration for experimental building of aviation equipment of the Air Force was signed in July 1957. Its second version (E-151) with a mobile cannon installation in the fuselage was studied simultaneously. The earliest version of preliminary design was developed in 1956. The basic tasks of the E-150 in the system "U-5" were formulated as follows: passive homing and automatic attack, interception and the destruction of the enemy bombers at supersonic speeds in any meteorological conditions and in the absence optical visibility. The aircraft had to be built in two copies with the following armament: - the first experiment with two radar guided missiles of the type K-6[v] or K-7[v], the installation on one pylon for the suspension of rockets was provided for on the lower surface of each outer plane of wing. The second experiment with the gun installation was mobile in two planes (chief designer [Fonakov]), which consisted of two guns [TKB]-495 of 30 mm caliber.

The E-150 outwardly appeared sharply different from all previously constructed machines. The aircraft was a midwing monoplane with a delta wing and round fuselage. The fuselage resembled a pipe from an elementary body of revolution with the practically identical diameter throughout the entire length (cylinder with a diameter of 1600 mm passed in the tail section in the zone of the afterburning engine chamber and its ejector into the cylinder with a diameter of 1650 mm). In the forward fuselage was established "multishock" cone from dielectric material, which consisted of three steps. Three-stage regulation served for the divergence of the shock wave before the air duct. The adjustment of entrance was achieved by the mobile cowling, which had two fixed positions. With reaching of the speed, equal Of [m]=1,65, the cowling automatically was shifted. With a decrease in the velocity it returned to the initial position. Anti-surge folds were placed on the sides of fuselage in the region of cab.

In it was arranged the antenna of the "Uragan-5[B]" radar. This radar with a long range of target detection could work in the regime of survey and target tracking. The radar was combined with the system of the fire control and receiving tele-command, and also autopilot of control. The interaction of these devices was accomplished under any weather conditions and at any time of day or night. It was directed from the earth automatic flight into the assigned zone with the subsequent target lock-on by signals RLS by the fulfillment of attack with the combination of purpose with the marker of the radar sight of aircraft.

The power plant consisted of one R-15-300 engine. This TRD (turbojet engine), which developed thrust by under maximum conditions 6840 kgf and under afterburner of 10,150 kgf, had a special ejector which made it possible to develop gross propulsive effort up to 19,800 kgf at the flight speeds in the range of the numbers of Mach 2.4-2.5 .

By September 1958 the first experimental model of interceptor E-150 stood in to the shop of the experimental production of OKB-155. It did not have identification number. More than six months (until June 1959) were required for the ground checks of the system of control and other systems of fighter. After the installation at the plant of the engine the aircraft again entered the airfield on 30 December 1960. In the process of ground tests it was necessary to replace the engine, and the interceptor proved to be ready for flight only in the middle of 1960 (because of the non-delivery of the engine it was delayed about 18 months). On 08 July 1960 the test pilot of OKB-155 [A]. [V]. Fedotov raised it into air.

In all in the machine they carried out 42 flights. The elements of weapon system were not checked. Because of the delays in the delivery of elements the systems "Uragan-5" of work on this copy were ended, and in further E-150 they used for flight tests and studies of the modernized engine R-15[M]-300 with improved upper-air data. The entire reserve of the second flying copy E-150 was used for the building of aircraft E-152. The machine, which was so necessary for PVO (Air Defense), seemed is at long last created. However, during the tests again there appeared problems with the power plant.