Mikoyan-Gurevich I-220

Mikoyan-Gurevich OKB

Industry	Aerospace, defense
Founded	1939 in Soviet Union
Founder	Artem Mikoyan, Mikhail Gurevich
Headquarters	Soviet Union
Products	Military aircraft, including the I-220 series prototypes

Template:Infobox aircraft The Mikoyan-Gurevich I-220 was a Soviet prototype designed as a high-altitude fighter during World War II. Conceived to address the challenge posed by German reconnaissance aircraft operating at high altitudes, a total of seven prototypes were constructed and evaluated in five distinct versions. By the year 1944, with the diminishing presence of German high-altitude threats, further production of the I-220 series was deemed unnecessary.

Design and development

In early 1941, the Soviet authorities issued a specification for a new fighter capable of intercepting enemy reconnaissance planes flying at elevated altitudes, such as the Junkers Ju 86. It was not until late 1942 that Mikoyan and Gurevich OKB received an order for two prototypes, initiating work on Samolet A (Aircraft A). The design, designated I-220 by the People's Commissariat of Aviation Industry (NKAP), featured an innovative structure primarily composed of shpon (wood veneer), supported by a steel-tube truss for the engine mount and a lightweight alloy tail assembly. The wing incorporated a CAHI laminar-flow airfoil, equipped with leading-edge slats and split flaps. Air intakes were positioned at the wing's leading edge near the roots. The tail resembled that of the I-230 but included a slightly larger tailplane span. Propulsion came from a 1,104 kW (1,480 hp) Mikulin AM-39 engine, although the initial prototype utilized a 1,104 kW (1,480 hp) Mikulin AM-38F paired with a three-bladed AV-5A propeller. The landing gear was conventional, with inward-retracting main wheels and a retractable tailwheel. Fuel was stored in six self-sealing tanks made from rubberized fabric—two located in the fuselage and four within the wings. The single-pilot cockpit featured a sliding canopy and was intended to be pressurized eventually; however, no pressurization system was installed. Armament plans included four ShVAK autocannons with 150 rounds each—two mounted above the engine and two alongside the crankcase. The first prototype carried only the upper pair of cannons, leaving the lower gun ports uncovered.

During summer 1942, as Ju 86R reconnaissance overflights persisted, development commenced on an enhanced I-220 variant optimized for stratospheric performance. This model, called I-221 or Samolet 2A, incorporated a redesigned wing with extended span and utilized a NACA-234 airfoil. Its outer wings and aft fuselage were constructed entirely from metal. Powerplant was upgraded to a 1,251 kW (1,678 hp) Mikulin AM-39A turbo-supercharged engine paired with a three-bladed propeller. The exact number of turbo-superchargers remains uncertain; some sources mention two TK-2B units while official MiG OKB drawings depict only one TK-2B mounted on the cowling’s right side. Notably, the I-221 introduced MiG’s first pressurized cockpit, which featured air conditioning via a heat exchanger located in an under-fuselage duct. Fuel capacity increased compared to the I-220, though precise figures are unavailable. Armament was reduced to two ShVAK cannons beside the engine, each supplied with 150 rounds; the upper pair was removed.

File:Mikojan-Gurevich i-222 3-view drawing.png

Three-view diagram of the I-222

The subsequent iteration, I-222 or Samolet 3A, closely resembled its predecessor but employed a 1,104 kW (1,480 hp) Mikulin AM-39B-1 engine equipped with a single TK-300B turbo-supercharger mounted on the left side of the cowling. Initially fitted with a three-bladed AV-5A propeller, this was later replaced by a four-bladed AV-9L-26 model. An intercooler for the turbocharger was housed within an enlarged air duct beneath the fuselage near the wing’s leading edge. The outer wings and rear fuselage reverted to wooden materials, with modifications lowering the rear fuselage slightly to enhance rearward visibility. Like the I-221, this version had a pressurized and air-conditioned cockpit; however, it added bulletproof glass—64 mm thick windscreen and rear panel—and armor plates measuring 8 to 9 mm on the pressure bulkhead. The sliding canopy included a reinforced metal frame that somewhat restricted visibility. Fuel capacity decreased due to removal of fuselage tanks. Armament matched that of the I-221 but ammunition per cannon dropped to 80 rounds.

The I-224 or Samolet 4A shared many features with the I-222 but introduced several alterations such as relocating the TK-300B turbo-supercharger to the right side and replacing wooden cockpit construction with welded aluminum alloy for pressurization. This variant was powered by a 1,052 kW (1,411 hp) Mikulin AM-39B engine driving a four-bladed AV-9L-22B propeller. The intercooler duct was deepened further. Both fuel capacity and ammunition load increased to 100 rounds per cannon.

The final evolution in this series was designated I-225 or Samolet 5A, reverting back to some design elements from the original I-220 but shifting focus away from high-altitude interception. It utilized a more powerful 1,750 hp (1,300 kW) Mikulin AM-42B engine coupled with a three-bladed AV-5A-22V propeller; notably, its cowling underside was deeper. Both wings and pressurized cockpit were constructed entirely from metal, featuring upgraded instrumentation and controls. The armored cockpit included a bulletproof windscreen and rear glass panel each measuring 64 mm thick along with seat armor plated at 9 mm thickness. Initially only one prototype was ordered; subsequently, a second unit powered by an AM-42FB engine rated at 1,228 kW (1,647 hp) followed.

Operational history

The initial I-220 prototype was unveiled at Khodynka in June 1943. Its maiden flight occurred in July 1943, with A. P. Yakimov as the test pilot. Evaluations showed generally positive performance, although the AM-38F engine demonstrated limited capability at low altitudes. The second prototype, equipped with an AM-39 engine and armed with four cannons each loaded with 100 rounds, was introduced in July 1943. Factory testing for this model took place from July to August 1943 before it was transferred to the Soviet Air Forces (VVS). Subsequent VVS testing occurred between 14 and 24 July 1944 but ended prematurely due to an engine malfunction. Meanwhile, the first prototype received an AM-39 engine upgrade, and flight trials with this powerplant were conducted from January through August 1944.

Testing of the enhanced I-221 commenced on 2 December 1943, with Yakimov piloting its inaugural flight; however, the aircraft was irreparably damaged following a belly landing. The closely related I-222 appeared on 23 April 1944 and first flew on 7 May, initially fitted with a three-bladed propeller and piloted by A. I. Zhukov. Shortly into its evaluation phase, the propeller was replaced by a four-bladed version. During these tests, the I-222 demonstrated superior high-altitude capabilities compared to all other Samolet A variants and achieved the highest service ceiling among Allied piston-engine fighters. Nevertheless, it was slower than other Samolet A models at lower altitudes. The VVS designated the production model of the I-222 as MiG-7, but by 1944, the urgency for a high-altitude fighter diminished, resulting in no production orders.

The I-224 prototype was completed in September 1944, with flight tests starting on 20 October under Yakimov’s control. This aircraft was lost after a supercharger failure caused an engine fire, forcing Yakimov to eject. The I-225 conducted its first flight on 21 July 1944, again piloted by Yakimov, completing fifteen flights over two days before an engine failure led to its destruction. The second I-225 underwent a brief testing period beginning on 14 March 1945 and proved to be the second-fastest Soviet piston-driven fighter, surpassed only by the VK-108-powered Yakovlev Yak-3.

Variants

File:Mikoyan-Gurevich I-220 and I-221 top-view silhouette comparison.png

I-220 (left) and I-221 (right)

I-220 (Samolet A)

Initial model utilizing either a Mikulin AM-38F or AM-39 engine. Two units constructed.

I-221 (Samolet 2A)

Designed for enhanced high-altitude performance featuring an extended wingspan and powered by an AM-39A turbo-supercharged engine. One unit built.

I-222 (Samolet 3A)

Derived from the I-221 but equipped with an AM-39B-1 turbo-supercharged engine along with additional modifications. One unit produced.

I-224 (Samolet 4A)

Based on the I-222 design but incorporating an aluminum cockpit structure. One unit completed.

I-225 (Samolet 5A)

Built upon the I-220 framework but fitted with a Mikulin AM-42B or AM-42FB engine and featuring metal wings and cockpit sections. Two units manufactured.

MiG-11

Intended designation for a planned production variant of the I-220 that was never constructed.

MiG-7

Assigned designation for a proposed production version of the I-222 which did not proceed to manufacturing. Not to be mistaken for the experimental MiG-3 variant sharing this name.

Operators

Template:USSR

• Soviet Air Forces