Polikarpov И-15 Чайка / I-15 Chaika
Technical Information

Background
Designed by Nikolai Polikarpov off the I-5, the И-15 Чайка / I-15 Chaika was a Soviet fighter aircraft. In Russian, Чайка (Chaika) means seagull. First flight October 1933 with production commencing in 1934. The revised version, the I-15bis with a longer wingspan un-gulled upper wing entered production in 1937. During 1937, Polikarpov Design Bureau submitted a proposal for a new fighter called I-153 (literally, I-15, 3rd version) that became the Polikarpov I-153 Чайка (Chaika, Seagull). The Chinese built the Chung 28B a version with Wright R-1820-F3 engine armed with four .30 caliber Browning machine guns.

Wartime History
During the Sino-Japanese War, the Chinese Kuomintang signed a non-aggression pact with the USSR and received a shipment of I-15s for the Chinese Air Force (CAF) and more than 250 Soviet pilots volunteered to fly I-15s. By 1939, the total number of Polikarpov biplanes delivered to CAF reached 347 I-15/I-15bis models in China.

During 1938 used in the Spanish Civil War with the first I-15s arriving at Cartagena on October 28, 1936, with 15 pilots led by Pavel Rychagov. Later, another ten pilots and fifiteen planes arrived at Bilbao. They entered combat on November 4, 1936 and claimed Ju-52 and two CR.32s over Madrid. In Spain, the I-15 was nicknamed "Chato" in Spanish meaning snub-nose.

During May-August 1939 used during the Battle of Khalkhin Gol / Nomonhan Incident. At the start, only fourteen I-15bis in the area were assigned to the 70th IAP. In the following weeks, reinforced by I-15bis from 22nd IAP from the Trans-Baikal region. During July 1939, ten I-15 were delivered to the the Mongolian People's Army Air Force and later more than thiry by 1942.

Their number increased in the following weeks: on 23 May, 35 I-15bis from 22nd IAP arrived from the Trans-Baikal region. However

Production
A total of 671 I-15s were built including 284 in the Soviet Union and 287 under license by CASA in Spain
A total 2,408 I-15bis were built between 1937–1940

Technical Details (I-15 M-25)
Engine  1 x Shvetsov M-62 1,000 hp 9 cylinder radial engine with a two bladed propeller
Wingspan  9.75 m (32 ft 0 in) upper and 7.50 m (24 ft 7 in) lower
Length  20' / 6.1m tail up in horizontal flight
Height  2.20 m (7 ft 3 in) with the tail down while parked
Maximum Speed  228 mph at 9,800' / 367 kmh at 3,000m
Range  320 miles
Armament  4 x 7.62mm PV-1 machine guns
Bombload  maximum of 100kg / 220 pounds of bombs under the wings