Polikarpov I - 3 The Polikarpov I - 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 Polikarpov DI - 1 were completed . Although the new biplane shared many of the characteristics of the earlier design , including the staggered sesquiplane layout of the wings , it was a new design . It was designed by the OSS ( — Landplane Department ) of " Aviatrest " ( Aviation Trust ) under the supervision of 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 Tornado 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 . The I - 3 had an oval - section semi - monocoque fuselage covered with ' shpon ' , molded birch plywood , with a small headrest faired into the fuselage , although the engine was enclosed in a metal cowling . The two - spar wings were covered in plywood and fabric and had a Clark Y profile . Internal bracing wires were fitted to reinforce the wings . The control surfaces were framed in duralumin , but covered in fabric . It was provided with differential Frise - type ailerons . The duralumin N - type struts that separated the wings , and attached the upper wing to the fuselage , had a teardrop profile . They were reinforced with steel bracing wires . The 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 . Two fuel tanks were fitted , the main one in the fuselage , but a small 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 of fuel was carried . Initially the I - 3 was fitted with two fixed synchronized Vickers machine guns , but these were later replaced by PV - 1 machine gun s . 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 bombs . 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 ( – Air Force Scientific Test Institute ) criticized the lack of directional stability at high speeds and a slight problem in control response between maneuvers . The area of the vertical tail was increased and the 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 , 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 . 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 . Operational use . Initial deliveries in 1929 were to units in the Belorussian Military District where they replaced the Grigorovich I - 2 . They equipped the 4th and 7th Squadrons ( – Air Squadron ) , later the 106th and 107th Fighter Squadrons ( — Fighter Air Squadrons ) at Smolensk ; the 13th and 5th Squadrons , later the 108th and 7th Fighter Squadrons , at Bryansk , the 9th Squadron , and the 17th and 19th Squadrons , which later became the 116th and 117th Fighter Squadrons . Units based in the Ukraine began to receive theirs the following year . They equipped the 3rd Squadron , later the 109th Fighter Squadron , and the 73rd Air Detachment ( " Aviaotryad " ) at Kiev and the 91st Squadron , later the 33rd Fighter Squadron , at Bobruisk . Others were delivered to the 1st , 2nd and 3rd Schools of Military Pilots . 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 . Variants . The DI - 2 ( ) 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 .