Editing Polikarpov I-15 (section)

==Design and development==
[[File:Polikarpov I-15 front quarter.jpg|thumb|Polikarpov I-15 showing gulled top wing]]
The design for the 14th fighter for the [[Soviet Air Forces|VVS]], the I-14, started as an advanced (for the era) monoplane under the direction of [[Andrei Tupolev]]. He grew concerned that the design would not mature, and ordered two backup biplane designs as the I-14A and B just to be safe. [[Nikolai Nikolaevich Polikarpov|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, a development of the [[Polikarpov I-5|I-5]] fighter became the famous '''I-15'''.{{Citation needed|date=January 2021}}

The first flight was made in October 1933 with [[Valery Chkalov|V.P. Chkalov]] at the controls, powered by an imported [[Wright R-1820 Cyclone]] engine.<ref name="Chaika p9">Green and Swanborough 1979, p. 9.</ref> The I-15, also known by its development name '''TsKB-3''', 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.<ref name="Chaika p10"/>

Production started in 1934, initially being powered by the [[Shvetsov]] M-22, a licence-built version of the [[Bristol Jupiter]] [[radial engine]].<ref name="Smith">{{cite book |last1=Smith |first1=Peter |title=Combat Biplanes of World War II |date=2014 |publisher=Pen & Sword |location=United Kingdom |isbn=978-1783400546 |pages=635}}</ref> While less powerful than the Cyclone, the M-22 powered aircraft were still superior to the I-5 which it replaced, demonstrating excellent manoeuvrability.<ref name="Chaika p10"/> Production switched to the {{cvt|515|kW}} [[Shvetsov M-25]] engine (a license-built, [[Metrication|metricified]] Cyclone) in late 1936.<ref name="Gunston Russian p299"/> A total of 671 I-15s were built, 284 in the Soviet Union and a further 287 under license by [[Construcciones Aeronáuticas SA|CASA]] in Spain.<ref name="Variants p120">Gordon and Dexter 1999, p. 120.</ref>

The gulled upper wing of the I-15 was unpopular with some pilots, as it was felt to restrict visibility, so Polikarpov's [[OKB|design bureau]] produced a revised version, again powered by the M-25, with a longer span un-gulled upper wing.<ref name="Smith" /><ref name="Gunston Russian p299"/> This version, the I-15bis, commenced production in 1937,<ref name="Chaika p18">Green and Swanborough 1979, p. 18.</ref> a total of 2,408 I-15bis' being delivered by the time production finished in 1940.<ref name="Gunston Russian p299"/>