Polikarpov I-3

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I-3/DI-2
Polikarpov I-3
Role Biplane fighter
National origin Soviet Union
Manufacturer Polikarpov
First flight 21 February 1928
Introduction 1929
Retired 1935
Primary user VVS
Produced 1928–1931
Number built 389 or 399

The Polikarpov I-3 (Russian: Поликарпов И-3) was a Soviet fighter designed during the late 1920s. It entered service in 1929, but was retired in 1935 with the advent of fighters with higher performance.

Design and development

Development of the I-3 began in mid-1926 after investigations into the loss of the

Nikolai Nikolaevich Polikarpov, head designer of the department. There was much debate within the OSS about the proper powerplant for the new fighter, but Polikarpov rejected the Wright Whirlwind radial engine and decided in favor of the BMW VI liquid-cooled V12 engine. A wooden mock-up was completed in April 1927, but formal approval of the design did not come until 3 June 1927. Static tests of a full-sized model began in October at the same time as negotiations for a license for the BMW engine were finished.[1]

The I-3 had an oval-section semi-

conventional undercarriage was fixed with rubber shock absorbers and the tailskid was made from duralumin. The main gear could be replaced by skis like those fitted to the Polikarpov R-1. The engine's semi-retractable radiator extended below the fuselage behind the rear main gear struts.[2] Two fuel tanks were fitted, the main one in the fuselage, but a small 2.5-litre (0.55 imp gal; 0.66 US gal) tank, mainly used to start the engine, was in the center section of the upper wing, along with the engine coolant tank. A total of 210 kg (460 lb) of fuel was carried. Initially the I-3 was fitted with two fixed 7.62 mm (0.300 in) synchronized Vickers machine guns, but these were later replaced by PV-1 machine guns. A central OP-1 optical gunsight was provided with a KP-5 ring sight offset to starboard. Some aircraft had bomb racks to carry two 11.5 kg (25 lb) bombs.[3]

The first prototype was completed in early 1928 and made its first flight on 21 February. Its manufacturer's trials were finished by 10 March and the state acceptance trials by 14 April. The pilots of the NII VVS (

elevators were given horn balances to alleviate the first problem while split ailerons addressed the second problem. Since production had begun before the aircraft was actually approved for service use, the first forty aircraft were completed with the smaller tailplane. A second prototype was completed in August 1928 and tested a different propeller optimized for high speed which increased the top speed to 283 km/h (176 mph), although it lengthened the take-off run. The first 39 aircraft completed, plus the two prototypes, used imported engines, but the remainder used the license-built Mikulin M-17.[1]

Approximately 400 were built, with Gordon and Dexter citing sources that state 389 or 399. They also provide a yearly production table that lists 35 built in 1928, 47 in 1929, 250 in 1930 and 55 in 1931, which add up to 389 when the two prototypes are included.[4]

DI-2

The DI-2 (Russian: ДИ-2 Dvukhmesnyy Istrebitel - two-seat fighter) was an enlarged two-seat variant. It had an extra frame added to the fuselage, an extended wingspan and an enlarged rudder. Two 7.62 mm DA machine guns were mounted on a Scarff ring in the observer's cockpit. A prototype was completed in early 1929 and made its first flight in May of that year. However the prototype crashed due to stabilizer failure in a dive later in 1929, killing the pilot.[2]

Operational use

Initial deliveries in 1929 were to units in the

Bobruisk. Others were delivered to the 1st, 2nd and 3rd Schools of Military Pilots.[5]

By 1 October 1930 252 I-3s were in service and 282 a year later. 297 were on hand on 1 January 1932, although it fell to 249 a year later and 239 towards the end of 1933. It was relegated to secondary roles in 1935 as newer and more powerful Polikarpov fighters entered service, notably the I-5, I-15, and the I-16.[6]

Operators

 Soviet Union
  • Soviet Air Force

Specifications (I-3)

Data from Istoriia konstruktskii samoletov v SSSR do 1938 g.[7]

General characteristics

Performance

  • Maximum speed: 278 km/h (173 mph, 150 kn)
  • Range: 585 km (364 mi, 316 nmi)
  • Service ceiling: 7,200 m (23,600 ft)
  • Time to altitude: 5,000 m (16,000 ft) 12 minutes 36 seconds
  • Wing loading: 66 kg/m2 (14 lb/sq ft)
  • Power/mass: 0.3 kW/kg (0.18 hp/lb)
  • Horizontal turn time: 14 sec

Armament

See also

Related lists

  • List of Interwar military aircraft

References

  1. ^ a b Gordon and Dexter, p. 7
  2. ^ a b Gunston, p. 292
  3. ^ Gordon and Dexter, pp. 7–8
  4. ^ a b Gordon and Dexter, p. 9
  5. ^ Gordon and Dexter, pp. 9–10
  6. ^ Gordon and Dexter, p. 10
  7. ISBN 5-217-03112-3
    .
  8. ^ Lednicer, David. "The Incomplete Guide to Airfoil Usage". m-selig.ae.illinois.edu. Retrieved 16 April 2019.

Bibliography

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