Category Mig

The engine flameout that occurred when all three cannons were fired at once puzzled OKB engineers and led them to examine the stability of the combustion process at that moment. This mystery was solved by degrees. It was thought that the solution lay in shifting the cannon

muzzles behind the engine air intake plane On the FR, all three can­nons were moved aft: the N-37 was relocated to the right side of the fuselage, and both of the NS-23s were placed on the left side. This new arrangement entailed a few structural modifications of the nose sec­tion. The two RD-20s were replaced by RD-21s built at an OKB man-

aged by D. V. Kolosov. This was basically a "hotted-up" RD-20 rated at 980 daN (1,000 kg st).

The FR was also equipped with airbrakes first tested on a UTI MiG – 9 as well as a pressurized cockpit. Five of the six original fuel tanks were retained—including a 100-1 (26-US gallon) trim tank—but the total capacity remained unchanged at 1,300 kg (2,865 pounds).

The first FR was rolled out in June 1947 and flown in July by V N. Yuganov. The data recorded during the flight tests showed that it was the first MiG to exceed M 0 8. Thanks to the greater thrust of the RD – 21, the level-speed increase reached 55 km/h (30 kt). The rate of climb also improved: the MiG-9M climbed to 5,000 m (16,400 feet) in 2 min­utes 42 seconds, 1 minute 36 seconds faster than any other aircraft in the same category.

The MiG-9M served as a basic model for the design of both the FL and the FN, two more powerful and sturdier versions that were built but never flown.

Specifications

Span, 10 m (32 ft 9.7 in); length, 9.83 m (32 ft 3 in); height, 3.225 m (10 ft 6.7 in); wheel track, 1 95 m (6 ft 4 8 in); wheel base, 3.072 m (10 ft 0.9 in); wing area, 18.2 m2 (195.9 sq ft); empty weight, 3,356 kg

(7,397 lb); takeoff weight, 5,069 kg (11,172 lb); fuel, 1,300 kg (2,865 lb); wing loading, 278.5 kg/m2 (57.1 lb/sq ft); max operating limit load fac­tor, 5.5.

Performance

Max speed, 965 km/h at 5,000 m (521 kt at 16,400 ft); max speed at sea level, 850 km/h (459 kt); climb to 5,000 m (16,400 ft) in 2.7 min; ser­vice ceiling, 13,000 m (42,640 ft); landing speed, 166 km/h (90 kt); range, 830 km (515 mi); takeoff roll, 830 m (2,720 ft); landing roll, 700 m (2,295 ft).

The MiG-15S bis and MiG-15R bis were both direct derivatives of the MiG-15 bis. The first was an escort fighter, the second a frontline photo­reconnaissance aircraft—two roles that demand long-range capabilities. The main difference between the MiG-15 bis and these two versions (other than the AFA-40 photo equipment on the MiG-15R bis) was the addition of two 600-1 (158-US gallon) drop tanks beneath the wing.

Considering the greater endurance made possible by those tanks, an additional 2-1 (0.53-US gallon) oxygen bottle was installed in the nose section, bringing the total oxygen reserve to 8 1 (2.11 US gallons). The additional takeoff weight also led the engineers to increase the tire pressure from 7 kg/cm2 (100 psi) to 8f05 kg/cm2 (113.8 psi) and to add restrictions to the flight protocols. Pilots were not allowed:

—to fly the aircraft under a negative load factor with full drop tanks —to make a long side-slip with full drop tanks (since a steady fuel draining could not be assured)

—to fly for a long time at speed limits

—to land with full drop tanks (they had to be jettisoned first)

The specifications and performance of the MiG-15S bis and MiG – 15R bis did not differ much from those of the MiG-15 bis, and both air­craft were held to the same speed and altitude limits as their precursor.

The SP-6 was basically a MiG-17PF fitted with an RP-1 Izumrud radar and four missile-launcher pylons under the wing. The air-to-air K-5 mis­sile (one per pylon) was renamed the RS-2U after its acceptance by the WS. Its semiactive radar seeker operated with the aircraft’s RP-1 radar. The experimental SP-6 retained one NR-23 cannon on the right side of

the nose, but on the assembly line this last cannon was removed. The MiG-17PFU thus became the first missile-only MiG fighter.

The SM-12PMU, built in 1958, was an SM-12PM powered by two Sorokin R3M-26 experimental turbojets with 3,725 daN (3,800 kg st) of thrust and one U-19D booster container under the fuselage that fea­tured a Sevruk RU-013 rocket engine with 2,940 daN (3,000 kg st) of thrust. The rocket engine could be relit several times in flight. The booster container also housed the necessary fuel and oxidizer tanks.

The SM-12PMU carried two semiactive homing K-5M (RS-2US) air – to-air missiles. Its maximum speed was identical to that of the PM at 1,720 km/h (929 kt) or Mach 1.69; the top speed attainable with the rocket engine was not recorded. Its navigational instruments were test­ed in late 1958 and early 1959. They were designed to receive and dis­play guidance signals transmitted by ground stations. The SM-12PMU was also used to develop the SOD decimetric wave transponder and the RV-U, a new type of precision radio-altimeter.

The Ye-152M was designed as a basis for the development of a highly sophisticated interceptor equipped with the most modern navigation and interception systems. It differed from the Ye-152 in the arrange­ment of its fuel tanks: there were the usual six fuselage tanks (no 1, 550 1 [145 US gallons]; no. 2, 1,100 1 [290 US gallons]; no. 3, 1,120 1 [296 US gallons]; no. 4, 120 1 [31.6 US gallons]; no. 5, 460 1 [121 US gallons]; no. 6, 3801 [100 US gallons]; total capacity, 3,7301 [984 US gallons]) and four wing tanks (two in front of and two behind the main spar, each capable of holding 600 1 [158 US gallons]), plus three tanks behind the cockpit in the dorsal spine of the fuselage (no. 1, 750 1 [198 US gallons]; no. 2, 6301 [166 US gallons]; no. 3, 3801 [100 US gallons]; total capacity, 1,760 1 [465 US gallons]). This overall capacity of 6,690 1 (1,766 US gal­lons) could be augmented by the 1,500 1 (396 US gallons) of the PB-

1500 drop tank, bringing the maximum fuel weight to 6,800 kg (14,990 pounds).

Except for the fuel tanks, the Ye-152M’s fuselage was identical to that of the Ye-152; but the ejector was replaced by a convergent-diver­gent exhaust nozzle that reduced the length of the fuselage by 253 mil­limeters. The tail units of the two aircraft were also identical.

The first version, called the Ye-152P, had a wing identical to that of the Ye-152 except for a small fence placed on the lower surface at midspan; also, the missiles were fired from the wing tips. Unfortunate­ly, this arrangement proved to be a failure. Because the wing tips were not sufficiently stiff to keep the launch rails steady, the missiles fol­lowed an uncertain trajectory and usually missed their targets. Engi­neers tried to remedy the situation by fitting the wing tips with pylons that were also supposed to serve as winglets. This improved conditions somewhat but still could not match those of the Ye-152A with its midspan pylons. Missile tests were finally discontinued.

To reduce its load, the wing was equipped with large tips that increased its span by 1,507 mm (4 feet, 11.3 inches). Moreover, the fuselage nose section was fitted with an auxiliary structure to hold a canard surface having a span of 3.5 m (11 feet, 5.8 inches), intended to improve the aircraft’s pitching stability above the sound barrier.

The Ye-152M did not fly with either the extended wing or the canard surface. But the aircraft became world-famous under the fancy designation Ye-166 when, with the short wing, it set the absolute world record for speed over a 100-km (62-mile) closed circuit at 2,401 km/h (1,297 kt) with A. V. Fedotov at the controls on 7 October 1961; the absolute world record for speed over a 15- to 25-km (9- to 16-mile) course at 2,681 km/h (1,448 kt) with G. K. Mosolov at the controls on 7 July 1962; and the world record for altitude at 22,670 m (74,360 feet) as well as for speed over a 15- to 25-km (9- to 16-mile) course with P. M. Ostapyenko at the controls on 11 September 1962. According to the documents submitted to the FAI to verify the record, the Ye-166 was powered by the R166 turbojet rated for 9,800 daN (10,000 kg st). This was not accurate: in fact, it used a reheated R-15B-300 capable of pro­ducing 10,975 daN (11,200 kg st). The Ye-152M test program was dis­continued afterward, and the OKB’s efforts were focused on an ambi­tious new design, the Ye-155—the future MiG-25.

Specifications

Span without enlarged wing tips, 8.793 m (28 ft 10.2 in); with enlarged wing tips, 10.3 m (33 ft 9.5 in); overall length (except probe), 19.656 m (64 ft 5.9 in); fuselage length (except cone), 16.35 m (53 ft 7.7 in); wheel track, 4.2 m (13 ft 9.4 in); wheel base, 6.265 m (20 ft 6.7 in); wing area (without enlarged wing tips), 42.89 m2 (461.7 sq ft).

The MiG-21R was a tactical reconnaissance aircraft derived at first from the MiG-21 PF, but the prototype did not have its broad-chord tail

The MiG-21 R’s first reconnaissance pods and the necessary wiring were tested on a MiG-21 PF airframe.

With 340 1 (90 US gallons) of fuel in the dorsal spine and broad-chord vertical tail sur­faces, the MiG-21 R was quite similar to the MiG-21S. In this photograph it carries the D-99 reconnaissance pod.

fin. All reconnaissance systems were gathered into a long streamlined pod under the center of the fuselage. The aircraft could also defend itself with two air-to-air missiles under its wing.

Powered by a R-l 1F2S-300 rated at 6,050 daN (6,175 kg st), the MiG – 21 R took advantage of the SPS system. The capacity of the fuel tanks in the dorsal fairing was raised to 340 1 (90 US gallons) to bring the total fuel capacity to 2,800 1 (740 US gallons). Because the aircraft could not cany a drop tank under the fuselage, the wing was equipped with the fuel pipes needed for two drop tanks holding 490 1 (129 US gallons) apiece The broad-chord tail fin was also retained. After all of these modifications, the aircraft looked veiy much like the MiG-2 IS.

Several types of pods were developed for this reconnaissance ver­sion: day and night reconnaissance photo equipment (forward-facing or oblique cameras), electronic intelligence (elint) sensors, as well as laser, infrared, and television detection systems. The aircraft’s wiring had to be modified accordingly. Among other significant changes, it is noteworthy that the KAP-2 autopilot (which provided only roll stabiliza­tion) was replaced by the three-axis AP-155. Moreover, the aircraft was equipped with the SPO-3 radar warning receiver. The airborne radar was the TsD-30, and underwing armament comprised two K-13T (R-3S) IR homing air-to-air missiles, and/or UB-16 and UB-32 rocket pods, S-24 rockets, and bombs. The GP-9 gun pod could also be added.

The MiG-21 R was mass-produced for the WS and for export in the Gorki factory between 1965 and 1971.

Specifications

Span, 7.154 m (23 ft 5.7 in); fuselage length (except cone), 12.285 m (40 ft 3.7 in); height, 4.125 m (13 ft 6.4 in); wheel track, 2.787 m (9 ft 1.7 in); wheel base, 4.71 m (15 ft 5.4 in); wing area, 23 m2 (247.6 sq ft); takeoff weight, 8,100 kg (17,850 lb); fuel, 2,320 kg (5,115 lb); wing load­ing, 321.2 kg/m2 (65.8 lb/sq ft); max operating limit load factor, 6.

Performance

Max speed, 1,700 km/h at 13,000 m (918 kt at 42,640 ft); max speed at sea level, 1,150 km/h (621 kt); climb rate at sea level (half internal fuel, full thrust) with reconnaisance pod and two R-3S missiles, 105 m/sec (20,670 ft/min); climb to 14,600 m (47,890 ft) in 8.5 min; ser­vice ceiling, 15,100 m (49,530 ft); landing speed, 250 km/h (135 kt); range, 1,130 km (700 mi); with two 490-1 (129-US gal) drop tanks, 1,600 km (995 mi); takeoff roll, 900 m (2,950 ft); landing roll with SPS and tail chute, 550 m (1,800 ft).

The initial production model of the 23-11 was to be equipped with the new Sapfir-23 radar and the more powerful R-27F2M-300 engine rated at 6,760 daN (6 900 kg st) dry or 9,800 daN (10,000 kg st) with after­burner The turbojet was ready in time; but unfortunately the radar was not, so the first aircraft had to make do with the Sapfir-21 With this older equipment the aircraft could carry at most four R-3S or R-3R missiles Besides the radar and engine, the MiG-23S differed from the 23-11/1, 23-11/2 and 23-11/3 prototypes in its equipment the ASP-PF computing fire control system, the TP-23 IR sensor and the ARK-10 automatic direction finder The radome was made of a new dielectric material

The first M1G-23S was conveyed to the test center on 21 May 1969 The next eight days were spent determining the aircraft s balance, test­ing the systems, and running up the engine The aircraft made its first flight on 28 May with A V Fedotov in the cockpit On 10 July the air­craft was moved to the firing range to assess the performance of the engine during armament trials By 20 August the MiG-23 had made thirty-two flights Its weapon system (same as that of the MiG-21S) and the Sapfir-21 radar were tested on the fifth production aircraft, and no serious difficulties were uncovered The built-in GSh-23L twm-barrel cannon was also fired. The SAU-23 automatic flight control system was checked but only in the stabilization mode, it would be developed more fully as the test schedule proceeded The SARP-12G emergency fault recorder was also developed The MiG-23S was really just a transi­tion model, and only fifty copies were built between mid-1969 and the end of 1970

Specifications

Span (72 sweep), 7 779 m (25 ft 6 3 in); span (16° sweep), 13 965 m (45 ft 9 8 in); fuselage length (except probe), 15 65 m (51 ft 4.1 in) wheel track, 2 658 m (8 ft 8 7 in), wheel base. 5 772 m (18 ft 11 3 in); wing area (72° sweep), 29 89 m2 (321,74 sq ft), wing area (16° sweep), 32 1 m2 (345 52 sq ft).

Performance

Max speed in clean configuration (72* sweep), 2,405 km/h or Mach 2 27 at 12,800 m (1,298 kt at 42,000 ft), max speed with four R-3S mis­siles (72” sweep), 2,100 km/h or Mach 1.98 (1,133 kt), max operating Mach number, 2 27; service ceiling in clean configuration, 18,000 m (59,040 ft), service ceiling with four R-3S missiles, 16,500 m (54,120 ft); feny range m clean configuration, 2,090 km (1,300 mi), ferry range

with four R-3S missiles, 1,800 km (970 mi); ferry range with 800-1 (211- US gal) drop tank, 2,500 km (1,350 mi); takeoff roll, 550-700 m (1,800-2,295 ft); landing roll, 450-600 m (1,475-1,970 ft).

These aircraft were subtypes of the MiG-25R, equipped with the next generation of reconnaissance systems, but the MiG 25RBK project had received approval at the same time as the MiG-25R The aircraft passed its combined state acceptance trials (reconnaissance and bomber mis­sions) and was produced in the Gorki factory between 1971 and 1980 The RBS variant was launched a little later, in 1965; it passed its com­bined acceptance tests and was produced between 1971 and 1977. The MiG-25RB, RBK and RBS were commissioned simultaneously.

More advanced systems were developed for the MiG-25RBS in the early 1980s After this upgrade in 1981 the MiG-25RBS was renamed MiG-25RBSh, and all of the MiG-25RBSs were gradually brought up to the RBSh standard with retrofit kits as they came in for their major overhauls. The mam difference between the MiG-25RB and the newer variants was the specialized electronic systems that replaced the cam­eras. and the modifications made to the cockpit, the power supply and the air-conditioning unit MiG-25RBFs (1981) were RBs that were updated to the RBK standard but still differed in some systems such as panoramic cameras, active and passive countermeasures and the like. The specifications and performance of those subtypes were practically identical to those of the MiG-25RB

Vladimir Yakovlyevich Klimov (1892-1962), member of the USSR Academy of Science, Hero of Socialist Labor, winner of the USSR State Prize, engineer major-general of aeronautical engineering

Klimov was educated in the automobile engine laboratory man­aged by the academician Ye. A. Chukadov. When the TsIAM was set up, he managed the gasoline engine department and was appointed professor. He lectured simultaneously at the Zhukovskiy military air academy. Then he went to France to negotiate the manufacturing license for the Hispano-Suiza twelve-cylinder V-type engine, which became in the USSR the M-100 rated at 750 ch. Derivatives of this engine —the VK-103, VK-105PF, and VK-107A—powered all of the Yakovlev fighters of World War II and the Petlyakov Pe-2 bomber. At the end of the war Klimov was developing the VK-108, but this engine never made it to production.

During one of the first postwar Paris air shows, Mikoyan and Klimov were able to examine the first Rolls-Royce centrifugal compres­sor jet engines. To pursue this technology, they went to Great Britain to order a small number of Nene turbojets. With these few engines, Klimov developed in the USSR the RD-45 for the MiG-15 fighter, the VK-1 for the MiG-17, and the reheated VK-1F for the MiG-17F. Later he designed the VK-5 and VK-7 experimental engines and developed the

VK-3, one of the very first turbofans, in close collaboration with one of his best assistants, Sergei Piotrovich Izotov.

Management of the Klimov OKB was entrusted to Izotov after its founder died in 1962. After graduating from the Leningrad polytechnic institute Izotov joined the OKB in 1941, where he became known over two decades for the turboshaft engines and reduction gears that he developed for the Mil and Kamov helicopters. But his first achieve­ments included the GTD-350 turboshaft, the VR-2 reduction gear for the Mi-2, and the TV2-117 and VR-8 reduction gear for the Mi-8. Izotov worked hard at the same time on powering tanks with gas turbine engines, and he succeeded in developing the RD-33, a very reliable tur­bofan used for the MiG-29. Izotov died in 1983 and was succeeded by V. Stepanov and A. Sarkisov, who is today in charge of the design bureau.

Aleksandr Aleksandrovich Mikulin (1895-1985), member of the USSR Academy of Science, Hero of Socialist Labor, winner of the USSR State Prize, engineer major-general.

The first 100-percent Soviet engine, the AM-34 was developed under Mikulin’s supervision in the 1930s. The first MiG fighter was powered by a Mikulin engine, the AM-35. He went on the develop experimental high-altitude turbocharged engines such as the AM-39 and AM-42B. During World War II his AM-38 and AM-42 engines pow­ered tens of thousands of П-2 and Il-l 0 shturmovik aircraft. After the war he developed the AM-3 turbojet for the first Soviet jet airliner, the Tu-104. His military turbojets powered mass-produced aircraft such as the MiG-19, MiG-21, and MiG-25, and he knew how to surround himself with talented assistants, namely, B. Stechkin, G. Livshits, S. Tuman – skiy, N. Metskvarshivili, V. Gavrilov, and K. Kachaturov.

Sergei Konstantinovich Tumanskiy (1901-73), member of the USSR Academy of Science, Hero of Socialist Labor, winner of the Lenin Prize and the USSR State Prize.

After graduating and soldiering at the Leningrad technical military school, the Zhukovskiy military air academy, and the TsIAM (central institute for airplane engine construction), Tumanskiy developed his first engine in 1938—the M-88, which powered the 11-4 bombers. In the early 1940s he joined the Mikulin OKB. In 1956 he was handed respon­sibility for developing the R-11F-300 twin-spool turbojet for the MiG-21 He kept the twin-spool layout for the R-11F2-300, rated at 6,000 daN (6,120 kg st), and the R-13-300, rated at 6,360 daN (6,490 kg st). Then he developed the R-27, rated at 7,645 daN (7,800 kg st), for the MiG-23 and the R-15B-300, rated at 10,000 daN (10,210 kg st), for the MiG-25

Pavel Aleksandrovich Solovyev (1917- ), chief constructor, cor­responding member of the USSR Academy of Science, doctor of techni­cal science, professor.

After graduating from the Rybinsk aeronautical institute, Solovyev joined the Shvetsov design bureau in 1939. Two years later he helped to launch the production of the ASh-82 radial engine and, later still, that of the ASh-82FN for the La-5 and La-7 fighters and that of the ASh – 82T for the 11-12 and 11-14 transport aircraft. The ASh-82 was selected in 1942 to power the DIS-200 (IT), and Solovyev personally supervised the installation of the engines on the MiG prototype. Then he worked with Shvetsov on the development of the most powerful piston engine of the time, the ASh-2K rated at 3,460 kW (4,700 ch)

Solovyev succeeded Shvetsov in 1953. The next year he began developing turbofan engines for airliners, the first of which was the D-

20 for the Tu-124. He worked simultaneously on the D-25V turboshaft engine and its R-7 gearbox for the Mi-6 and Mi-10 heavy helicopters. Pursuing his turbofan line of products, between 1964 and 1966 he designed the D-30, rated at 6,665 daN (6,800 kg st), for the Tu-134 air­liner. It was the first Soviet engine to be certified worldwide Surprising as it may seem, the D-30 is still the core of tlje D-30F6 reheated turbo­fans, rated at 15,190 daN (15,500 kg st), that power the MiG-31 intercep­tor. Today the design bureau, located in Perm, works under the leader­ship of Yuri E. Reshetnikov on various versions of the PS-90 turbofan to power several types of airliners.

Notes:

“TJ = turbojet, Lj = lift jet, TF = turbofan, AB = afterburner, SS = single spool, TS = twin spool bEHM = electro-hydromechamcal, HE = hydroelectronic. HM = hydromechanical cFirst figure is low-pressure stage number, second is high-pressure stage number dWhen the SPS (flap blowing) system is in use, 3,330 daN (3,400 kg st)

APPENDIX 3.

Machine Guns and Cannons on MiG Fighters

[1]A single-engine fighter program that led to development of the Yak 15 and La-150 was launched at the same time as the twin-engine effort that produced the MiG-9 and Su-9.

[2]For various reasons, the designation MiG-23 was granted to other aircraft; but its final holder was the 23-11, a mass-produced VG fighter.

This was the first MiG-21 armed with air-to-air missiles, the first to be mass-produced, the first to be exported, and the first to be built outside the USSR (in Czechoslovakia, in India, and in China). It may be regard­ed as the basic model of the entire family. That is why we will devote special attention to this machine. But first it must be stated that the MiG-21F-13 did not come into its final silhouette until aircraft no. 115 left the assembly line. Starting with this aircraft, the fin height was reduced and its chord was increased. The following details refer to the final model, except where otherwise noted.

The MiG-21F-13 delta wing, like that of its predecessors, had a 57- degree sweepback at the leading edge and a 2.2 aspect ratio The wing airfoil was a TsAGI S-12 with a thickness ratio of 4.2 percent at the wing root and 5 percent at the wing tip; incidence, 0 degrees; anhedral,

[4] degrees; maximum chord, 5.97 m (19 feet, 7 inches); mean aerody­namic chord (MAC), 4.002 m (13 feet, 1.6 inches). The small fence that can be seen in front of each aileron had a height equal to 7 percent of the MAC. The trailing edge of each wing was fully occupied by a single – slotted flap of 0.935 m2 (10.1 square feet) and an inset aileron of 0.51 m2 (5.5 square feet). The flaps were hydraulically controlled, and the ailerons were hydraulically boosted by two BU-45 servo-control units. The wing structure was organized around three spars:

1. A front spar preceded by twenty-five ribs that were square to the leading edge, and a front false spar; the front wet wing tank was located ahead of that spar, close to the wing root

2. A center beam that was square to the fuselage datum line; the wheel was stored between the front spar and the center beam,

[5] Time to climb to 6,000 m (19,680 feet), 1 minute, 0 1 seconds

[6] Time to climb to 3,000 m (9,840 feet), 41 2 seconds

3. Time to climb to 9,000 m (29,520 feet), 1 minute, 21 seconds

[8] Time to climb to 12,000 m (39,360 feet), 1 minute, 59 3 seconds

The last refinement of the two-seat version, the MiG-21UM differed from its predecessor chiefly in its upgraded instrumentation. The KAP-

[10] autopilot was replaced by the three-axis AP-155 (the MiG-21R and all subsequent versions of the aircraft were fitted with the AP-155). The aircraft was also equipped with the ASP-PDF computerized optical fire control. The forward equipment bay received a plug-in rack to reduce maintenance downtime. The MiG-21UM was also powered by the R – 11F2S-300, rated at 6,050 daN (6,175 kg st). The total capacity of the fuel tanks was 2,450 1 (647 US gallons).

The MiG-21 UM succeeded the US on the assembly line in the Tbi­lisi factory in 1971 (for the VVS and export).

The MiG-211 was the test bed for the wing of the Tupolev Tu-144 supersonic airliner, allowing engineers to work out its airflow charac­teristics and test the whole flight control system. For the latter the

ОКБ engineers had to start from scratch since this was their first pure delta-wing aircraft.

[11]A few months after entering service, the MiG-25R was seen in Egypt Four aircraft of that type were delivered to Cairo by Antonov An-22 heavy cargo aircraft. The first reconnaissance missions over Israel set out from that airport in October 1971; the pilots and the field support crew were Soviets The aircraft flew in pairs, their mis­sions covering the Israeli coast and the Sinai Peninsula, at speeds above Mach 2 35 and altitudes above 20 000 m (65,000 feet). It was more a “loan” than a true export venture

As development of the MiG-25 continued, various spinoff projects were considered. One of the most interesting—and unexpected—of these was a business jet (to be more precise and respect the Soviet ter­minology, “administrative" jet) designed between 1963 and 1965 to carry six passengers or an equivalent cargo load.

Even though Aeroflot might have evinced some interest in this air­craft, it was from the outset the OKB’s project; but it was more than a stylistic effort, and the design was carried to an advanced stage. One of

During the flight tests of the family s basic aircraft, the MiG-25P and MiG-25R, the pilots reported that—because of the peculiar flight enve­lope of those machines, especially its speed and altitude components— it was imperative to build a separate two-seat trainer for each of the two central missions, interception and reconnaissance. That is how the MiG-25PU and RU project started. The first one was completed in 1968, the second in 1972.

Both versions were unarmed and had no combat capabilities. In the preliminary design the ОКБ emphasized the greatest possible com­monality not only between the two aircraft but also between the train­ers and the basic versions. The MiG-25PU differed from the MiG-25RU only by its cockpit firing simulator. Unlike in the MiG-23 two-seater, the instructor was seated in the front cockpit. All control systems as well as a number of other systems (static and dynamic pressure indica-

The FP was designed solely to control the harmful effects of cannon fire on the combustion stability of the engine. It differed from the FS in only one point: the N-37 cannon was moved from the air intake split­ting wall to the left upper part of the fuselage nose. This new arrange­ment did not solve the problem.