I-15, TsKB-3 by N.N.Polikarpov

I-15 with M-22 engine, 8k drawing from "History of aircraft construction in the USSR" by V.B.Shavrov, Vol.1 p.486

A
small biplane fighter, development of the I-5 and I-6 with improved airdynamic. The most distinctive features were gulled upper wing and very clean fixed landing gear, often covered with fairing. Roots of the upper wing were included into fuselage structure. Upper wing shape improved pilot view and reduced drag.
Front section of the fuselage from engine to cockpit was covered with duralumin sheets, the rest of aircraft - with fabric. Wheels were equipped with disk brakes. First aircraft was equipped by imported 630/715hp high altitude Wright-Cyclone SGR-1820 F-3 engine. Armament included pair of synchronized PV-1 machineguns and 40kg of bombs (overload). Interestingly, the tail of the first TsKB-3 carried same letters VT as the VT-11 prototype of the I-5.
Flight tests were performed in October-November 1933 by V.P.Chkalov. The second prototype - on skis - was flown in December. During continuous dive one of skis was lost, and aircraft turned over during landing. Series production of I-15 started.
Early series were powered by Wright-Cyclone engine. Planned production of its license version M-25 was delayed, and during 1934-36 few hundred of I-15 were equipped with M-22. Interestingly, low altitude performance did not suffer despite less powerful engine was used. Since 1936 all production aircraft had M-25 engine, demonstrating improved performance at high altitudes. Production aircraft carried four PV-1 machineguns or (in 1938) pair of 12.7mm BS heavy machineguns.
Stripped version of the I-15 was used in 1935 by V.K.Kokkinaki to set the World altitude record (14,575m). Series of trials were performed in 1937 with pressurized cockpit. They had no value for series I-15 (due to ceiling), but those were first successful tests of pressurized cockpits on Soviet fighters.
Gull-wing caused heated debates among specialists and pilots, despite the I-15 was superior compared with other contemporary fighters. As a result N.N.Polikarpov had to convert design back to conventional wing. This conversion forced production delay in 1936 (only 12 I-15 rolled out). But while large series with straight wing started in 1937 (picture below), extensive airdynamic tests at TsAGI proved advantage of the gull wing at high speeds. As a result in 1938 I-15 production continued with (modified) gull wing.
Straight-winged I-15 of 1937 series (104k!) from 'Aviatsia i Vremia' ('Aviation and Time') magazine, courtesy of Sergey Andreev

The I-15 was used in combat in Spain and proved to be one of the best fighter biplanes of its time. Performance was high enough to force pilots of early Bf-109 to avoid close combat with more agile and well-armed 'Chato'. But biplane era was already fading, and in 1939 during clashes with Japanese I-15 was already obsolete.
I-15 deserves special honor from American military pilots. It was flown by ace of Spanish War Frank G. Tinker, who became the first American to shot down Messerschmitt Bf-109...
674 (?) built.
Technical data
Type I-15, TsKB-3 I-15 M-22 I-15 M-25
Function Fighter
Year 1933 1933 1934
Crew 1
Engines 630/715hp Wright- Cyclone 480hp M-22 630/715hp M-25
Length 6.1m
Wingspan 9.7m
Wing area 14.0m2 + 7.9m2
Empty weight 965kg 1106kg 960kg
Loaded weight 1374kg 1415kg 1369kg
Wing load 62.8kg/m2 64.6kg/m2 62.6kg/m2
Power load 2.18kg/hp 2.95kg/hp 2.17kg/hp
Speed at 0m 318km/h 286km/h 315km/h
Speed at 3000m 368km/h 350km/h 367km/h
Landing Speed 90km/h
Landing Roll 6sec
70m		 -
Takeoff Roll 4sec
70m		 -
Turn time 8.3sec 8.0-8.5sec
Range 500km - 550km
Flight Endurance 2.6h - 2.6h
Ceiling 9800m 7250m 9800m
Climb
1000m 1.1min - 1.1min
3000m 3.4min 5.6min 3.3min
5000m 6.2min 11min 6.1min
7000m 11min - -
9000m 24min - -
Armament
Guns 2*7.62mm PV-1 4*7.62mm PV-1 750rpg
or
2*12.3mm BS
Bombs-100kg
Rockets - optional rails for 6*RS-82
Predecessors Modifications

I-5
I-6
I-152 I-15bis
I-153 I-15ter
LinksReferences
  • I-15 at the Virtual Aircraft Museum
  • I-15, Polikarpov
  • Polikarpov I-15 in the Spanish Civil War
  • "History of aircraft construction in the USSR" by V.B.Shavrov, Vol.1 p.485-488;
    		•
    Modified February 04, 1998
    by Alexandre Savine
    and Sergey Andreev;    		 Back to
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