This frontline fighter-interceptor was a special version of the MiG-21 PF developed to be built under license in India and for export. Externally both aircraft were very similar, but the MiG-21 FL had the same engine as the MiG-2 IF the R-l 1F-300—and the total capacity of the fuel tanks was increased to 2,900 1 (766 US gallons). Moreover, the RP-21 radar was replaced by the R-2L, a less advanced export model.
The MiG-21FL was built in the MMZ Znamya Truda factory in Moscow between 1965 and 1968 and by HAL in India from 1966 onward.
Span, 7.154 m (23 ft 5.7 in); fuselage length (except cone), 12.285 m (40 ft 3.7 in); wheel track, 2.692 m (8 ft 10 in); wheel base, 4.806 m (15 ft 9.2 in), wing area, 23 m2 (247.6 sq ft), takeoff weight in clean configuration, 7,830 kg (17,255 lb); max takeoff weight, 9,400 kg (20,715 lb); max takeoff weight on rough strip or metal-plank strip, 8,100 kg (17,850 lb); wing loading, 340.4-408.7-352.2 kg/m2 (69.8-83.8-72.2 lb/sq ft); max operating limit load factor, 8.
Max speed, 2,175 km/h at 13,000 m (1,175 kt at 42,640 ft); max speed at sea level, 1,130 km/h (610 kt); climb rate at sea level in clean confi – uration, 175 m/sec (34,450 ft/min); climb to 18,500 m (60,700 ft) in 8 min; service ceiling, 19,000 m (62,300 ft); landing speed, 280 km/h (151 kt); range, 1,450 km (900 mi); with 800-1 (211-US gal) drop tank, 1,800 km (1,120 mi); takeoff roll, 850 m (2,790 ft); landing roll with tail chute, 850 m (2,790 ft).
Work on the Ye-8 frontline fighter-interceptor got under way in 1961 by government decree. It was referred to as the MiG-23 (the second aircraft to go by that name). Basically it was a modified MiG-21 PF airframe reengined with the more powerful R-21 turbojet and equipped with the new Sapfir-21 radar in the nose. The antenna diameter of this radar forced the manufacturer to move the air intake under the cockpit. To simplify the mass production of the future MiG-23, which was intended to replace the MiG-21 PF on the assembly lines, the Ye-8 received the same on-board systems as the MiG-21. The Ye-8 requirement called for a fighter capable of intercepting and destroying intruders in the front and rear sectors twenty-four hours a day and in any weather conditions.
The production MiG-21 wing retained for both Ye-8 prototypes was not fitted with the SPS system of flap blowing, and the stabilator, also taken from the MiG-21 assembly line, was lowered by 135 millimeters (5.3 inches) below the fuselage datum line. Other noteworthy technical innovations were also made:
1. Under the tail of the fuselage there was a ventral fin that folded to starboard when the landing gear extended, the hinge control being slaved to the gear’s follow-up linkage. Tested for the first time on the Ye-8, this type of ventral fin was later included on the production MiG-23 (the one with a VG wing).
2. A foreplane—or more precisely a rotating delta canard surface— with a span of 2.6 m (8 feet, 5.4 inches) was set immediately behind the radome. This "destabilizing” surface was not controlled by the pilot. In subsonic flight it behaved like a weathercock; at Mach 1 and beyond, it was mechanically set to a neutral position in relation to the aircraft’s datum line, modifying the aerodynamic center and reducing the margin of pitch stability (unnecessary at supersonic speeds).
The R-21F that powered the Ye-8 was in fact an R-11F modified by N Metskhvarishvili and rated at 4,605 daN (4,700 kg st) dry or 7,055 daN (7,200 kg st) with afterburner (an outstanding afterburning ratio of
53 percent). Compared to the R-11F, the R-21F had a diameter of 845 mm (33.26 inches) versus 772 mm (30.39 inches), a nozzle throat diameter of 987 mm (38.86 inches) versus 902 mm (35.51 inches), and a dry weight of 1,250 kg (2,755 pounds) versus 1,165 kg (2,568 pounds). The ventral air intake was divided into two ducts by a three-step splitter
The 81 or Ye-8/1 consisted of a MiG-21 PF airframe drastically modified to make room for the Sapfir-21 radar antenna.
that could be adjusted electrohydraulically. The front gear leg retracted into the splitter. The main gear, taken from a production MiG-21 of the Ye-7 type, was strong enough to withstand takeoffs and landings on rough strips. The flying controls and the hydraulic system were those of the MiG-21, except for devices linked to the canard surfaces and the folding ventral fin. The armament specified for the Ye-8 was two K-13 air-to-air missiles, but neither the missiles nor the radar were ever installed.
The Ye-8/1, which bore the marking "81" on the sides of its fuselage just under the cockpit, was moved to the test center on 5 March 1962. Its R-21F no. 21-205 turbojet was intended only for ground tests and was later replaced by the flight-cleared R-21F no. 21-106. The first flight, on 17 April 1962 with G. K. Mosolov at the controls, went off without incident. For the first five flights all systems were tested, the engine was put through its paces (including relight in flight at up to 8,000 m [26,240 feet]), and the directional stability was controlled. The next six flights were dedicated to measuring accelerations at various Mach numbers and reaching the service ceiling. The operation of the canard surface was checked at the same time.
After one engine surge and one flameout on the twenty-first and twenty-fifth flights, the R-21F no. 21-106 was replaced by no. 21-108, an
The 82 or Ye-8/2, here armed with K-13 missiles, was flown only thirteen times before its tests were halted
engine with a larger turbine nozzle. On 11 September 1962 the engine burst at Mach 1 7 at 10 000 m (32,800 feet). Mosolov ejected but was seriously wounded and bad to be taken to a hospital.
The Ye-8/2 (or "82”) was flight-tested thirteen times by A V Fedotov from 29 June to 4 September 1962. But all flights were canceled after the Ye-8/1 crash. The inquiry revealed that the accident was due to the breakup of a part of the sixth compressor stage rotor. Once it came loose it ripped through the engine casing and the aircraft’s skin and hit the wing, demolishing the aileron. The plane entered a tailspin at 5,000 m (16,400 feet). The sudden loss of thrust led to a surge in the compressor and the air intake ducts During the subsequent rapid deceleration the aircraft suffered severe lateral oscillations, a phenomenon observed in previous flights after the pilot had intentionally cut off the engine At this point the aircraft was practically uncontrollable.
Span, 7 154 m (23 ft 5.7 in); length (except probe), 14.9 m (48 ft 10.6 in); wheel track, 2.787 m (9 ft 1.7 in); wheel base, 3.35 m (10 ft 11.9 in); wing area, 23.13 m2 (249 sq ft), takeoff weight, 6,800 kg (14,985 lb);
max takeoff weight, 8,200 kg (18,070 lb), wmg loading, 294-354.5 m2 (60.3-72.7 lb/sq ft).
Max speed, 2,230 km/h (1,204 kt); service ceiling, 20,000 m (65,600 ft).