Kochyerigin DI-6

Kochyerigin DI-6 (internal designation TsKB-11; Russian: Кочеригин ДИ-6/ЦКБ-11) was a two-seat fighter biplane produced in the Soviet Union in the 1930s.

DI-6 was developed at TsKB as a fighter that would also be capable of ground attack when fitted with different armament. Originally intended to use a liquid-cooled V-12 engine, problems with its development led to the choice of the Wright R-1820 radial engine instead. The first flight took place on 30 September 1934, and testing began in earnest in early 1935, with State Acceptance Trials following between May and November. 

Despite a number of weaknesses discovered during testing, the type was ordered into production, and deliveries to the Air Force commenced in spring 1937. Problems including excessive vibration, and a poor field of fire for the gunner, were never adequately resolved, and the various fixes implemented to cure these and other problems eventually added around 160 kg (350 lb) to the aircraft's weight. Production continued until 1939.

DI-6 was a conventional single-bay biplane of mixed construction with cable-retracted main landing gear. The pilot and the tail gunner sat in tandem cockpits, the pilot's open, and the gunner's partially enclosed. To maximize the gunner's arc of fire, the rear cockpit was set lower in the fuselage than the pilot's.

Pre-Glastnost Western sources often reported these aircraft as having participated in the Battle of Khalkhin Gol against Japan in 1939, and even in the Winter War against Finland, but more recent scholarship has failed to uncover any evidence that it was deployed in either case. 

A replica DI-6 is displayed in Victory Park, at the Museum of the Great Patriotic War, Moscow.

Variants
DI-6bis
Trainer with fixed landing gear.
DI-6Sh (TsKB-11Sh, TsKB-38)
Ground attack variant with armored pilot's seat and four forward-firing PV-1 machine guns under the bottom wing; 60 built.
DI-6MMSh
One prototype with M-300 X engine, did not enter production.

Operators: Soviet Air Force
Specifications DI-6
General characteristics

Crew: Two
Length: 6.87 m (22 ft 6 in)
Wingspan: 9.94 m (32 ft 7 in)
Height: 3.2 m (10 ft 6 in)
Wing area: 25.15 m² (270.7 ft²)
Empty weight: 1,360 kg (2,998 lb)
Loaded weight: 1,955 kg (4,310 lb)
Powerplant: 1 × Shvetsov M-25 radial engine, 522 kW (700 hp)
Maximum speed: 372 km/h (201 knots, 231 mph)
Range: 500 km (270 nm, 311 mi)
Service ceiling: 7,700 m (25,262 ft)
Wing loading: 78 kg/m² (16 lb/ft²)
Power/mass: 267 W/kg (0.16 hp/lb)
Time to altitude: 10 min to 5,000 m (16,400 ft)
Horizontal turn time: 12 sec
Armament: 3× 7.62 mm (0.3 in) ShKAS machine guns, two unsynchronized firing forward and one on a rear-facing mount, 750 rounds/gun
Up to 40 kg (88 lb) of bombs