Tupolev ANT-31 / I-14
Possessing the distinction of being the world's first all-metal single-seat cantilever monoplane fighter to be graced with a retractable main undercarriage and an enclosed cockpit, the ANT-31 was designed at the KOSOS TsAGI by Pavel O Sukhoi's brigade. Featuring a smooth, stressed-skin fuselage with corrugated skinning for the wing, tailplane and rudder, the first prototype was powered by a 580hp nine-cylinder Bristol Mercury VIS2 radial, and had a manually-operated inwards-retracting undercarriage and an aft-hinging cockpit canopy incorporating the windscreen. This aircraft entered flight test with a fixed-ski undercarriage early in May 1933, by which time major redesign was being undertaken and work had begun on a second prototype, the ANT-31bis.
Fitted with a 712hp Wright Cyclone SGR-1820-F2, the ANT-31bis featured a new, narrow-track undercarriage retracting outwards and a narrower canopy which, sliding fore and aft on runners, still incorporated the windscreen. This aircraft, too, was initially flown with fixed skis, in March 1934, and, equipped with an armament of two 37mm Kurchevski APK-11 recoilless guns installed immediately outboard of the wing centre section and one fuselage-mounted 7.62mm machine gun, then underwent State testing from the following October.
The decision was taken to initiate series production of the ANT-31bis as the I-14bis, with smooth metal skinning overall, an open cockpit with fixed windscreen, the 700hp M-25 licence-built version of the Cyclone and armament of two 20mm cannon and two 7.62mm machine guns. Orders were placed for 55 I-14bis fighters, the intention being to install the 730hp M-25A engine at an early stage. The spin recovery characteristics of the I-14bis were not entirely satisfactory and difficulties were experienced with the narrow-track undercarriage. In consequence, the similarly-powered I-16 Tip 4 having meanwhile demonstrated generally superior characteristics, production was terminated in December 1936 with the 18th aircraft, the remaining 37 fighters of this type then under construction being scrapped.
Max take-off weight: 1540 kg / 3395 lb
Empty weight: 1170 kg / 2579 lb
Wingspan: 11.20 m / 37 ft 9 in
Length: 6.10 m / 20 ft 0 in
Wing area: 16.90 sq.m / 181.91 sq ft
Max. speed: 440 km/h / 273 mph
Tupolev ANT-31 (I-14)