Mikoyan-Gurevich MiG-15 - Design and Development

Design and Development

The first Soviet turbojet fighter developed by Mikoyan-Gurevich was the Mikoyan-Gurevich MiG-9 NATO reporting name: Fagot which appeared in the years immediately after World War II. It used a pair reverse-engineered German BMW 003 engines, which had been experimentally used on the Messerschmitt Me 262A-1b test aircraft, only a few of which were ever built. The MiG-9 was a troublesome design which suffered from weak, unreliable engines and control problems. Categorized as a first generation jet fighter, it was designed with straight wings like previous piston-engined fighters which were encountering performance problems as their performance approached the speed of sound.

The Germans never developed good turbojets with thrust over 2,500 lb which limited the performance of Soviet jet designs. By 1946, Soviet designers were impressed by the Rolls Royce Nene engine. Soviet aviation minister Mikhail Khrunichev and aircraft designer A. S. Yakovlev suggested to Premier Joseph Stalin the USSR buy advanced jet engines from the British. Stalin is said to have replied, "What fool will sell us his secrets?"

However, he gave his consent to the proposal and Mikoyan, engine designer Vladimir Klimov, and others travelled to the United Kingdom to request the engines. To Stalin's amazement, the British Labour government and its pro-Soviet Minister of Trade, Sir Stafford Cripps, were perfectly willing to provide technical information and a license to manufacture the Rolls-Royce Nene. This engine was reverse-engineered and produced as the Klimov RD-45, subsequently incorporated into the MiG-15. Rolls-Royce later attempted to claim £207 million in license fees, without success.

To take advantage of the new engine, the Council of Ministers ordered the Mikoyan OKB to build two prototypes for an advanced high-altitude day interceptor to defend against bombers. It was to have a top speed of 621 miles per hour and a range of 745 miles.

Designers at MIG's OKB-155 started with the earlier MiG-9 jet fighter. The new fighter used Klimov's new British designed engines, and applied swept wings and a tailpipe which went all the way back to a swept tail. Germany was the first nation to fit their Me 262 with a 18.5° wing sweep, but it was introduced merely to adjust the center of gravity of heavy engines. Further experience and research during World War II later established that swept wings would give better performance at transonic speeds. At the end of World War II, the Soviets seized most of Germany's aircraft industry. The MiG team studied many of these plans, prototypes and documents, particular swept-wing research and designs. The swept wing later provided a decisive performance advantage over straight-winged jet fighters when it was introduced into combat over Korea

What emerged had a mid-mounted 35 degree swept wing with a slight downward anhedral and a tailplane mounted up on the swept tail. Western analysts noted that it strongly resembled Kurt Tank's Focke-Wulf Ta 183, which was a never-flown swept-wing follow-on to the Me 262 designed during World War II. The MiG-15 bore a much stronger likeness than the American F-86 Sabre which also incorporated German research, though the new MiG retained the previous straight-winged MiG-9's wing and tailplane placement, and the F-86 inherited its low-wing from the Fury (which in turn had wings similar to the P-51). The two aircraft were otherwise similar enough in appearance to prompt US forces to paint their planes with bright stripes to distinguish them. The Soviets did capture the plans and prototypes for the Ta-183. The majority of Focke-Wulf engineers (in particular, Hans Multhopp, who led the Ta-183 development team) were captured by Western armies. It has been argued that the MiG-15 design team drew some limited inspiration from the Ta-183, but it is disputed that it was heavily influenced. One view is that the MiG-15 is an original design benefiting from German research, but conceived, designed, engineered, and produced by the Soviets. The unusual MiG-8 Utka experimental canard aircraft, built right at the conclusion of World War II by the MiG design bureau also lent experience in the use of swept wings on later Mikoyan designs.

The resulting prototypes were designated as I-310. The I-310 was a clean, swept-wing fighter with 35° sweep in wings and tail, and exceptional performance, with a top speed of over 1,040 km/h (650 mph). The design used a single engine fed by a split-forward air intake. A duct carried intake air around the cockpit area and back together ahead of the engine. First fight was 30 December 1947 (The similar American F-86 Sabre had first flown only months earlier in October 1947).

Russia's first swept-wing jet fighter was actually the underpowered Lavochkin La-160 which was otherwise more similar to the MiG-9. The Lavochkin La-168 which reached production as the Lavochkin La-15 used the same engine as the MiG but with shoulder mounted wing and t-tail was the main competitive design. Eventually, the MiG design was favored for mass production. Designated MiG-15, the first production example flew on 31 December 1948. It entered Soviet Air Force service in 1949, and subsequently received the NATO reporting name "Fagot." Early production examples had a tendency to roll to the left or to the right due to manufacturing variances, so aerodynamic trimmers called "nozhi" (knives) were fitted to correct the problem, the knives being adjusted by ground crews until the aircraft flew correctly.

An improved variant, the MiG-15bis ("second"), entered service in early 1950 with a Klimov VK-1 engine, an improved version of the RD-45/Nene, plus minor improvements and upgrades. Visible differences were a headlight in the air intake separator and horizontal upper edge airbrakes. The 23 mm cannons were placed more closely together in their undercarriage. Some "bis" aircraft also adopted under-wing hardpoints for unguided rocket launchers or 50–250 kg (110–551 lb) bombs. Fighter-bomber modifications were dubbed "IB", "SD-21", and "SD-5". About 150 aircraft were upgraded to SD-21 specification during 1953–1954. An unknown number of aircraft were modified to "IB" specification in the late 1950s.

The MiG-15 arguably had sufficient power to dive at supersonic speeds, but could not do so because it did not have an "all-flying" tail. As a result, the pilot's ability to control the aircraft deteriorated significantly as it approached Mach 1. Later MiGs incorporated all-flying tails.

The MiG-15 was originally intended to intercept American bombers like the B-29. It was even evaluated in mock air-to-air combat trials with a captured U.S. B-29, as well as the later Soviet B-29 copy, the Tu-4 "Bull". To ensure the destruction of such large bombers, the MiG-15 carried cannons: two 23 mm with 80 rounds per gun and a single 37 mm with 40 rounds. These weapons provided tremendous punch in the interceptor role, but their limited rate of fire and relatively low velocity made it more difficult to score hits against small and maneuverable enemy jet fighters in air-to-air combat. The 23 mm and 37 mm also had radically different ballistics, and some United Nations pilots in Korea had the unnerving experience of 23 mm shells passing over them while the 37 mm shells flew under. The cannons were fitted into a neat pack that could be winched down out of the bottom of the nose for servicing and reloading, in principle allowing a pre-prepared pack to be switched for rapid turnaround. (Some sources mistakenly claim the pack was added in later models.)

A variety of MiG-15 variants were built, but the most common was the MiG-15UTI (NATO reporting name "Midget") two-seat trainer. Because Mikoyan-Gurevich never mass-produced the transition training versions of the later MiG-17 or MiG-19, the MiG-15UTI remained the sole Warsaw Pact advanced jet trainer well into the 1970s, the primary training role being fulfilled exclusively by Czechoslovak Aero L-29 Delfin and the L-39 Albatros jet trainers (save for Poland, which used their indigenous TS-11 Iskra jets). While China produced two-seat trainer versions of the later MiG-17 and MiG-19, the Soviets felt that the MiG-15UTI was sufficient for their needs and did not produce their own trainer versions of those aircraft.