DI-6. The world’s first biplane fighter with the retractable landing gear

Specifications

Crew: 2 people.

Maximum take-off weight: 1955 kg

Dimensions: length x wingspan: 7.0 x 10.0 m

Powerplant: number of. engine x power: 1 (M-25) x 700 hp

Maximum flight speed: at an altitude of 3000 m: 372 km / h

Rate of climb (average): 10.2 m / s

Practical ceiling: 7700 m

Flight range: 500 km

Armament: three 7.62 mm ShKAS machine guns

Features

• Plumage and rudders had linen sheathing;

• Wings are pasted over with a cloth;

• Steel brace bands provided the necessary strength and rigidity of the biplane wing box;

• Metal two-bladed propeller with a change in installation angle before take-off;

• The main landing gear with brake wheels retracted into the center section with a cable drive;

• The fuselage had a lightweight outer frame sheathed in the back of the canvas;

• The crutch was oil-air cushioned;

• The cockpit was open, with a protective visor;

• The arrow cabin was stubbed recessed into the hull, had partial glazing;



History

Domestic aircraft designers worked hard to create a two-seat fighter. This task was complicated by the inevitable increase in the mass and size of the aircraft, provided the second crew member was placed, in addition, such a machine should have the characteristics no worse than single-seat fighters.

The clumsy and heavy aircraft designed before in the USSR (2I-N1, DI-2, DI-3, DI-4) were inferior to single-seaters in speed and were not so maneuverable. Many aircraft designers of the USSR curtailed development work due to setbacks.

One of the few who did not abandon this idea is aircraft designer V.P. Yatsenko, who worked in the Design Bureau of S.A. Kocherigin, in 1934 developed a double fighter DI-6. An unconventional approach in designing was to compact the layout scheme, as a result of which the new machine was almost equal in size to the I-15.

The mixed design was a truss, welded from the pipes of the fuselage. The wing posts were made of metal, the wing spars were wooden, and the wing trim and tail section were made of canvas. The aircraft was equipped with a Wright-Cyclone engine with a capacity of 640 hp, closed by an annular hood. Later it was replaced with its licensed copy – the M-25 engine with a capacity of 630/700 hp.

The engine was started from an electric starter, a manual drive and through a ratchet on a screw.

The DI-6 aircraft became the world’s first biplane fighter with the retractable landing gear. The chassis as a whole turned out to be successful, which significantly reduced the aerodynamic drag of the car. A retractable ski landing gear was also developed for the aircraft.

The courage of the designer in the layout and technology favorably affected the flight performance. The aircraft possessed good speed and maneuverability and was stable in diving. According to the main characteristics, the DI-6 was only slightly inferior to the single-seat fighters I-15, I-15bis, I-153 “Seagull”. The participation of the new aircraft in hostilities confirmed the quality factor of the design.

The DI-6 two-seat fighter successfully passed tests in mid-1935 and was put into service. Produced during 1937 and 1938. At two aircraft factories, a total of 200 copies were built, including modifications.

The armament was made up of three ShKAS machine guns: two of them were mounted in the lower wing outside the propeller disk and one on the pivot mount to protect the rear hemisphere, with ammunition of 750 rounds per machine gun. Up to 50 kg of bombs (8-10 kg each) could be mounted on the lower suspension.

DI-6 aircraft proved their effectiveness in air battles with Japanese bombers and fighters during the war in Mongolia in the summer of 1939.

The assault version of the DI-6Sh proved to be quite good in the winter of 1939 in the war with Finland. In addition, fighters DI-6 were used at the beginning of the Great Patriotic War.

The Luftwaffe officially considered DI-6 until April 1942 a full-fledged combat aircraft.

Graduated from Embry-Riddle Aviation University with a master's degree in aviation science. He began his career as an aviation researcher in local periodicals. Has a pilot license. Now are the author and developer of the Plane Worlds.