The Mikoyan-Gurevich DIS (/ Dalnij Istrebitel' Soprovozhdenya – "long-range escort fighter") was a prototype Soviet heavy fighter of World War II, envisioned to serve primarily in the escort fighter role. The service designation MiG-5 was reserved for the production version of the aircraft. Competing designs in the USSR included the Grushin Gr-1, Polikarpov TIS and Tairov Ta-3. It was intended to develop reconnaissance and bomber versions but these plans were disrupted by Operation Barbarossa, the German invasion in June 1941. The project failed due to its disappointing Mikulin AM-37 engines and when a second prototype was built with M-82 radial engines its performance was mediocre. The design was cancelled in 1943 after at least two prototypes had been built. Design and development The NKAP (Narodnyy komissariat aviatsionnoy promyshlennosti—People's Ministry of the Aircraft Industry) requested on 7 October 1940 that the OKO (opytno-konstrooktorskiy otdel—Experimental Design Department) of Factory (Zavod) No. 1, which would later become the Mikoyan-Gurevich design bureau (OKB) begin work on a twin-engined long-range, single-seat escort fighter intended to use the AM-37 engine, then under development by Mikulin. It also requested that specifications, along with a model, be ready to be discussed on 12 November of that year. Three days later Mikoyan and Gurevich were ordered to produce three prototypes to undergo State acceptance trials on 1 August, 1 September and 1 November 1941. After the meeting, the NKAP broadened its roles to include bombing, torpedo attack, reconnaissance and interdiction. A low-wing, twin-engined, twin-tailed monoplane, the DIS was of mixed construction. The front section was built from duralumin, the middle section was a wooden monocoque and the rear section was steel tubes covered with a duralumin skin. The twin tails were wooden and had an electrically operated variable-incidence horizontal stabilizer. The elevators had duralumin frames, but were covered by fabric. The two-spar wing was made in three pieces. The center section was metal, but the outer panels were wooden with fabric-covered ailerons and veneer-covered Schrenk flaps. The wing had leading edge slats along two-thirds of its length. The main undercarriage retracted rearwards into the rear of the engine nacelles and the tailwheel retracted into the rear fuselage. The Mikulin AM-37 inline engines were slung underneath the wings with the engine oil coolers mounted in the outer wing panels. The air intakes for the engine superchargers were located in the wing leading edge. The pilot was provided with a glass