Polikarpov I-185

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The Polikarpov I-185 was a Soviet fighter aircraft designed in 1941. It never entered production.

Contents 1 Development 1.1 Technical description 2 Specifications (I-185 (M-71)) 3 See also 4 References 4.1 Notes 4.2 Bibliography

[edit] Development

In 1939 the Soviet Air Force was in need of a modern monoplane fighter comparable with new foreign designs. One of the most active designers at that time was Nikolai Nikolaevich Polikarpov who had previously designed the I-15 and I-16 fighters, which earned him his nickname "The King of Fighters." Polikarpov continued his design work despite the Polikarpov I-180 not entering production, his design bureau being reduced and relocated, his preliminary interceptor fighter design I-200 being taken away from him and completed by Mikoyan-Gurevich (becoming the MiG-3), and Polikarpov himself losing Stalin's favour after the death of Valery Chkalov in a Polikarpov I-180.

After a tour of the German aviation industry in 1939, Polikarpov decided the only way to compete with new designs like the Focke-Wulf Fw 190 was to take advantage of the powerful two-row radial engines being developed at the time. The I-185, designed in early 1940, had clearly evolved from the I-180, itself a development of the I-16. It was initially designed for the Tumansky M-90 engine of 1,305 kW (1,750 hp). The first prototype was completed on May 25, 1940, but the only available copy of the M-90 was unfit for test flights. Therefore, the design was adopted for the larger and heavier Shvetsov M-71 engine (essentially, two Shvetsov M-62 engines sandwiched together) of 1,492 kW (2,000 hp). When this was delayed, the design was changed again, this time to accept the Shvetsov M-81 with 1,194 kW (1,600 hp). The M-81 delivered to Polikarpov was defective and after another delay the I-185 (M-81) finally took to the air on January 11 1941. The M-81 was plagued by vibrations and it was decided not to pursue further development with that engine. The prototype was rebuilt as I-185 (M-71), flying again on May 29, 1941. Another prototype took to the air on April 8, 1941. In the summer of 1941, two additional prototypes were completed with Shvetsov M-82 engines of 1,268 kW (1,700 hp) and armament of three 20 mm ShVAK cannons instead of machine guns in the earlier prototypes.

Because of the German attack, the aircraft were evacuated from Polikarpov's factory No.51 to Novosibirsk in October 1941, where the factory was deployed in a circus building. In March 1942 the aircraft completed government trials with very good results. Maximum speed of the I-185 (M-71) was 630 km/h (390 mph), and the I-185 (M-82A) reached 615 km/h (382 mph). Its handling was also very good. The conclusion was, the I-185 (M-82A) was superior to every Soviet fighter except the I-185 (M-71), which was recommended for production. The fifth aircraft, built in June 1942 as a production line pattern with the M-71 engine, reached a maximum speed of 667 km/h (414 mph).

In 1942, it was decided to test I-185 prototypes in combat conditions. Four aircraft (two I-185 (M-71) and two I-185 (M-82)) were tested in the 728th Guards Fighter Regiment (728 GIAP), 3rd Air Army, on the Kalinin Front from December 9 1942 to January 13 1943. In order not to lose aircraft, pilots were ordered not to engage in combat manoeuvres and not to fly over enemy territory. Pilots' reports were quite enthusiastic; they especially emphasized its speed (higher than of any other Soviet fighters including the Yak-7B and La-5), vertical manoeuverability thanks to the strong engine, strong armament and ease of flying. Importantly, I-185 flying characteristics were similar to the I-16's, which made the transition easy for even moderately experienced pilots. It was recommended to put the I-185 to production after minor improvements.

At the same time, further government trials of the I-185 (M-71) were carried out. The aircraft was reported to temporarily exceeded 700 km/h (435 mph) in some flights. The results were very satisfactory and test pilots wrote a letter to Stalin discussing the I-185 advantages and urging him to put it into production as soon as possible. In February 1943, the preparations to produce I-185 started in No.81 factory in Moscow, but in April all work was cancelled after a fatal crash of an I-185 (M-71) prototype on April 5 due to engine failure. Despite all its advantages and successful design, the Soviet aviation authorities decided not to make the I-185 a standard fighter, officially because of the concern that implementation of the new design would temporarily slow down fighter production. The fact that M-82 was already being used by La-5 fighters and that M-71 was still unreliable also played a role. No doubt, a significant part was played by pressure from Polikarpov's competitors and Stalin's favorites Yakovlev and Lavochkin.

Nonetheless, Polikarpov attempted to advance the I-185 design with I-187 with a M-71F engine of 1,640 kW (2,200 hp), bubble canopy, four 20 mm cannons and an estimated maximum speed of 710 km/h (440 mph), and the I-188 with an improved M-90 engine with 1,552 kW (2,080 hp). Proposals for the I-195 biplane based on I-185 with an estimated speed of 591 km/h (367 mph), and a two-seat trainer DIT-185 remained on paper. Polikarpov died at the age of 52 on July 30 1944 from esophageal cancer, his death effectively putting an end to the I-185. His factory No.51 later became home to the Sukhoi OKB.

[edit] Technical description

The I-185 was a single-seat, single-engine, low-wing monoplane fighter of mixed construction with a plywood semi-monocoque fuselage and duraluminum wings. Pilot sat in a fully enclosed cockpit. Landing gear was retractable with a retractable tail wheel. The two-row air-cooled radial engine turned a three blade propeller 3.2 m (10 ft 6 in) in diameter.

[edit] Specifications (I-185 (M-71))

General characteristics

• Crew: One
• Length: 7.77 m (25 ft 6 in)
• Wingspan: 9.80 m (32 ft 2 in)
• Height: 2.50 m (8 ft 2 in)
• Wing area: 15.53 m² (167.10 ft²)
• Empty weight: 2,654 kg (5,840 lb)
• Loaded weight: 3,500 kg (7,700 lb)
• Powerplant: 1× Shvetsov M-71 radial engine, 1,492 kW (2,000 hp)

Performance

• Maximum speed: 630 km/h (391 mph)
• Range: 835 km (520 mi)
• Service ceiling 11,000 m (36,080 ft)
• Rate of climb: 16.1 m/s (3,150 ft/min)
• Wing loading: 225 kg/m² (46 lb/ft²)
• Power/mass: 430 W/kg (0.26 hp/lb)

Armament

• 3x 20 mm ShVAK cannons
• Up to 500 kg (1,100 lb) of bombs (2 x 250 kg (550 lb) or 4 x 100 kg (220 lb)) or 8x RS-82 rockets

[edit] See also

Related development

• Polikarpov I-16
• Polikarpov I-180
• Polikarpov I-195
  

Comparable aircraft

• Lavochkin La-5
• Lavochkin La-7
• MiG-3
• Focke-Wulf Fw 190
• P-47 Thunderbolt
• Nakajima Ki-84
  

[edit] References

[edit] Notes

[edit] Bibliography

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