The Polikarpov I-15 “Seagull”
The Polikarpov I-15 (Russian: И-15) was a Soviet biplane fighter aircraft of the 1930s. Nicknamed Chaika (“Seagull”) because of its gulled upper wings, it was operated in large numbers by the Soviet Air Force, and together with the Polikarpov I-16 monoplane, was one of the standard fighters of the Spanish Republicans during the Spanish Civil War, where it was called Chato (snub-nose) in the Republican Air Force, or “Curtiss” because its resemblance to Curtiss F9C Sparrowhawk in the Nationalist Air Force.
The design from the start was for an advanced monoplane under the direction of Andrei Tupolev. When He grew concerned that the design would not mature, and ordered two backup biplane designs, just in case, as the I-14A and B to be safe.
Polikarpov had just been released from prison in August 1932, and was handed the I-14A project. When both the I-14 and I-14A were ordered into production, Polikarpov’s design was a development of the I-5 fighter became the famous I-15.
The first flight was made in October 1933 with V.P. Chkalov at the controls, powered by an imported Wright R-1820 Cyclone engine. The I-15 was a small biplane fighter with a gulled upper wing. The single bay wings were of wooden construction, while the fuselage was of mixed steel and duralumin construction, with a fabric covered rear fuselage.
Production started in 1934, initially being powered by the M-22, a licensed built version of the Bristol Jupiter radial engine. While less powerful than the Cyclone, the M-22 powered aircraft were still superior to the I-5 which it replaced, demonstrating excellent maneuverability.
More than 1,000 I-15bis fighters were still in Soviet use during the German invasion when the biplane was employed in the ground attack role. By late 1942, all I-15s and I-15bis’ were relegated to second line duties.