MiG Experimental Heavy Interceptors

Purpose: To create a supersonic missile­armed all-weather interceptor.

Design Bureau: OKB-155 ofA I Mikoyan

I-3U, I-7U, I-75

In the second half of the 1950s the ‘MiG’ de­sign team created a succession of interceptor fighters which began by reaching 870mph and finished 1,000mph faster than that. The first was the I-1, first flown on 16th February 1955, which resembled a MiG-19 powered by a single large VK-7 centrifugal engine. After a major false start, this led to the I-3U, which (contrary to many reports) was flown in late 1956 on the 8,440kg (18,607 Ib) thrust of a VK- 3 bypass jet (low-ratio turbofan). By this time the aerodynamic shape, and indeed much of the structure and systems, was extraordinari­ly similar to the contemporary Sukhoi proto­types. The next stage was the I-7U, flown on 22nd April 1957, which used the engine picked earlier by Sukhoi, the excellent Lyul’- ka AL-7F rated at 9,210kg (20,304Ib). In turn this was rebuilt into the I-75, first flown on 28th April 1958. This was the first of the fami­ly of impressive MiG single-engined heavy in­terceptors, with powerful radar (Uragan [hurricane] 5B) and armed only with missiles (two large Bisnovat K-8). A second aircraft was built from scratch, designated I-75F and powered by the uprated AL-7F-1 with a max­imum thrust of 9,900kg (21,8251b). The fol­lowing specification refers to the I-75.

Ye-150

This was built specifically to test the remark­able R-15 turbojet, created by S KTumanskii, initially working in A A Mikulin’s KB, which he took over in 1956. This engine had been or­dered to power future aircraft flying at up to Mach 3 (the first application was a Tupolev cruise missile). The MiG team led by Nikolai Z Matyuk predictably adhered to the proven formula of a tube-like fuselage with a variable multi-shock nose inlet, mid-mounted delta wing (the I-75 had had swept wings) and mid­mounted swept one-piece tailplanes. This time the fuselage had to accept the R-15-300 en­gine’s take-off airflow of 144kg (317.51b) per second, and the dry and reheat ratings of this engine were 6,840kg (15,080 Ib) and 10,150kg (22,3771b). At high supersonic Mach numbers the thrust was greatly increased by the ejector – type nozzle, a very advanced propulsion sys­tem for the 1950s. As the Ye-150 was not a fighter the cockpit was enclosed by a tiny one – piece canopy of minimum drag. After pro­longed delays, mainly caused by the engine, the aircraft was flown by A V Fedotov on 8th July 1960. It required frequent engine replace­ment, but among other things it reached 2,890km/h (l,796mph, Mach 2.72), climbed to 20km (65,617ft) in 5min 5 sec, and reached a sustained altitude of23,250m (76,280ft).

Ye-152A

This was essentially an interceptor version of the Ye-150, but with the important difference that it was powered by a pair of mature R-l 1F – 300 (early MiG-21 type) engines, with a com­bined maximum thrust of 11,480kg (25,309 Ib). The airframe was designed to a load factor of 7, and 4,400 litres (968 Imperial gallons) of fuel was provided in six fuselage and two wing tanks, and provision was made for a centreline drop tank. The Ye-152A was designed for al­most automatic interceptions, guided by the Uragan-5 ground-control system and its AP-39 autopilot, finally locking on its own T sP-1 radar and firing the two MiG-developed K-9-155 mis­siles carried on down-sloping underwing py­lons. This fine aircraft was first flown by Mosolov on 1 Oth July 1959 (more than a year before the Ye-150) and it reached 2,135km/h (l,327mph, Mach 2.01) at 13,700m (44,950ft). It caused a sensation when it made a flypast at the 1961 Tushino airshow, being identified by Western experts as the (MiG-23′ because that was the next odd number after the MiG-21. After a busy career it crashed in 1965.

Ye-152

This was intended to be the definitive heavy interceptor, combining the R-l5-300 engine (uprated to 10,210kg, 22,509 Ib) with the air­frame and weapons of the Ye-152A. Two were built, Ye-152/1 and Ye-152/2. Apart from hav­ing a large single engine the obvious new fea­ture was that the Ye-152/1 carried its K-9 missiles on down-sloping launch shoes on the wingtips. Internal fuel was slightly increased, and avionics were augmented. From its first flight on 21st April 1961 it was plagued by en­gine problems, but eventually set a 100km closed-circuit record at 2,401km/h (1,492 mph, Mach 2.26), a straight-line record at 2,681km/h (l,666mph, Mach 2.52) and a sus­tained-height record at 22,670m (74,377ft). These were submitted to the FAI as having been set by the ‘Ye-166’. In fact both Mosolov and Ostapenko achieved 3,030km/h (1,883 mph, Mach 2.85). The Ye-152/2 was intended to have the Smerch (whirlwind) radar and as­sociated Volkov K-80 missiles, but this was never incorporated. It first flew on 21st Sep­tember 1961, and after a brief factory test pro­gramme was rebuilt into the Ye-152P.