After operational tests of the MiG-3 powered by the M-82, produced in a small batch of five aircraft designated MiG-9 M-82, one more modification was built in 1943, this time with a boosted engine. The fighter was designated I-211No.211 (or Type 'E'). Its fuselage was reshaped to give a smoother transition from the cowling and controllable gills to the side panels, the cockpit was moved a little further aft, the air intakes of the oil cooler were positioned in the wing centre section leading edge near the fuselage sides, the shape of fin was changed and the tailplane was raised. Two ShVAK synchronised guns were housed in the wing centre section.
The flight test data obtained in 1943 were quite good. The maximum speed at 23,000ft (7,000m) was 416mph (670km/h), and only four minutes were required to climb to 16,400ft (5,000m). The second I-211 (E) prototype, which was also undergoing production tests, was not placed into series-production. Instead, the new Lavochkin La-5FN fighter with the same ASh-82FN engine (the M-82 was redesignated in 1943 by giving it the initials of designer Arkady Shvetsov) was put into series-production, using a well-developed manufacturing base, and proved itself at the front line.
I-220
The I-220(A) prototype was designed for the new 1,700hp (1,268kW) Mikulin AM-39. Pending its installation, however, the fighter was submitted for its official state flight tests in January 1944 with a production AM-38F engine with poor altitude capability. The aircraft's structure was otherwise unchanged. Thus powered, and at a flying weight of 7,8791b (3,574kg), the I-220(A) had a maximum speed of 386mph (622km/h) at 13,750ft (4,200m), service ceiling of 31 ,000ft (9,500m) and a range of 596 miles (960km). Two guns instead of four were installed, with 300 rounds.
By the summer of 1944 the AM-39 high altitude engine had been developed, and one had been installed in place of the AM-38F. Armament remained the same. Flight test data obtained during the production development tests in July and August 1944 showed a slight improvement. At gross take-off weight of 8,0401b (3,647kg) maximum speed at sea level was 354mph (571km/h), while at 25,600ft (7,800m) it was 433mph (697km/h). Time to climb to 16,400ft (5,000m) was 4.5 minutes.
For the official tests conducted at the NII WS in September the I-220(A) was powered by a production AM-39 engine and carried its full complement of four ShVAK guns, but the ammunition was slightly reduced at 400 rounds. At an increased take-off weight of 8,4541b (3,835kg) the maximum speed fell to 415mph (668km/h) at 22,300ft (6,800m), the service ceiling was 36,000ft (11,000m) and the time taken to reach 16,400ft (5,000m) was 6.3 minutes. These tests revealed a number of shortcomings, including excessive aileron and elevator loads on the control column, poor rearward view, and difficulty in achieving full undercarriage retraction without the help of pilot-induced 'g' loads.
Although the I-220(A) outperformed the operational series-production fighters, it did not go into production in 1944 because Lavochkin and Yakovlev types completely met the WS requirements and could provide the desired air superiority in dogfights with German fighters. A family of new high altitude fighter-interceptors based on the I-220(A) was developed later.
I-222
Because of the accident with the I-221 (2A) one more aircraft, the I-222 (production code '3A') prototype high altitude interceptor, was manufactured. This differed from its predecessor in having a pressurised cockpit, and for the first time in a Soviet aircraft a special cooler was provided to cool the air entering the carburettor after the first compression stage by means of the AV-9L26 four-bladed propeller. The I-222(3A) was powered by a Mikulin AM-39B-1 with a single TK-300B turbosupercharger working from the port exhaust manifold, and ejector exhaust pipes were fitted on the starboard side. Take-off power was 1,860hp (1,387kW), and at 43,300ft (13,200m) the powerplant developed 1,430hp (1,066kW).
The aircraft had two 20mm ShVAK guns, the canopy was protected front and rear by armoured glass, and pilot's seat had an armoured backrest. The airframe was of mixed construction. The machine differed from the I-221 (2A) in having the radiator moved forward from below the cockpit to a position under the engine.
The new fighter was completed in April 1944 and made its maiden flight on 7th May, being tested by A Yakimov, a highly skilled test pilot. Its speed at 22,000ft (6,700m) was 423mph (682km/h), and at 41,000ft (12,500m) it was 429mph (691km/h). Its service ceiling was 47,500ft (14,500m), a record for Soviet Second World War fighters. However, the aircraft did not go into series-production because the Mikoyan bureau was working on a better aircraft of this type, the I-224(4A).
I-225
By the summer of 1944 Mikoyan had produced another prototype, designated I-225 (production code 'SA'). Dimensions and wing area were the same as those of the I-220(A), but it had the new AM-42B engine rated at 2,000hp (1,492kW) and a TK-300B turbosupercharger. Armament consisted of four ShVAK synchronised guns. A. Yakimov piloted it on its maiden flight, on 21 st July 1944, and during tests it reached a speed of 437mph (704km/h) at 25,500ft (7,800m). However, on 9th August, during its fifteenth flight, the aircraft was damaged in an accident.
The second version, powered by the boosted AM-42FB engine with a TK-300B turbosupercharger and with pilot visibility improved, did not embark on its flight test programme until 14th March 1945, by which time the war's outcome was decided and there was no longer an urgent demand for high altitude fighters. Moreover, combat actions were now conducted outside Soviet territory. The aircraft did not achieve production.
I-230
The first prototype of the I-230(0) modified fighter went for testing in July 1943. At that time it was called the 'improved' version of the MiG-3, but later it was designated MiG-3U. The tests were conducted at the NII WS by leading test pilot V Khomyakov. The maximum sea level speed was 313mph (505 km/h), 326mph (526km/h) being reached with engine boost. At 23,000ft (7,000m) the aircraft attained 407mph (656km/h), exceeding the speed of the series-production MiG-3 by 24.8mph (40km/h). It took only 6.2 minutes to climb to 16,400ft (5,000m), compared with 7.1 minutes for the MiG-3. Service ceiling was 2,300ft (700m) higher at 39,000ft (11,900m). The I-230(0) had a range of 807 miles (1,300km).
Although the aircraft's combat features were obviously improved, pilots noted a number of shortcomings, including difficult or even dangerous landing characteristics for inexperienced pilots. After close examination of the MiG-3U's performance, the acceptance commission at the NII WS withheld its recommendation to put the improved aircraft into series-production. (MiG-3U - usovershenstvovanny, improved.) Nevertheless, the Mikoyan Design Bureau and Aircraft Plant No.155 managed to produce another five prototypes of the fighter, and in August 1943 the first, third, fourth and sixth prototypes were delivered for operational tests to the 12th Guards Fighter Air Regiment, then defending Moscow. As a result, the MiG-3U gained some approval, although a number of defects were also noted. The type was not put into series production, and the design bureau began to develop new high altitude fighters.
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