Developed from the uncompleted Tupolev ANT-36 (DB-1), a single-engined long-range bomber based on the ANT-25, the Tupolev ANT-37 (DB-2) long-range bomber was developed by Sukhoi’s design brigade under Tupolev’s overall control.

The Tupolev DB-2 (ANT-37) long-range bomber, designed in the autumn of 1934, could carry a 2,200 lb bomb load over a range of 3,100 miles at a speed of 155 m.p.h.

The prototype flew on 16 June 1935, powered by two 597kW Gnome-Rhone 14Kdrs engines, broke up in mid-air in August 1935 owing to buffeting of the tail unit. Test pilot K. Popov and the flight engineer managed to bale out, but a third crew member did not survive the crash.

The second prototype, powered by licence built Gnome-Rhone M-85s, was tested and refined throughout 1936. It was then transferred to the Nauchno Issledovatelsky Institut Voyenno-Vozdushnykh Sil (NII V-VS – Scientific Research Institute of the Air Force) for State tests, which continued until mid-1937. It was admitted that the DB-2 was inferior to Ilyushin’s DB-3 bomber in several respects, particularly maximum speed (200 m.p.h. and 248 m.p.h. respectively), so further development was abandoned.

When the second DB-2 prototype had completed its State tests it was proposed that it be handed over to the Tsentralniy Aero-Gidrodinarnicheskiy Institut (TsAGI, the Central AeroHydrodynamic institute) for further refinement and additional flight tests. Another DB-2 was completed and handed over to a Soviet Air Force (V-VS) unit for training personnel in endurance and long-range flying.

Having undergone modification, the second prototype was provided for the long-distance flight to be undertaken by Grizodubova, Raskova and Osipenko. it was completely stripped of armament, fitted with additional fuel tanks to ensure a maximum range of 4,350 miles and given new flight instruments and 950 h.p. licence-built Gnome-Rhone M-86 engines.

The DB-2D was followed in turn by the DB-2B or ANT-37bis, of which only three were built as record breakers/research aircraft after rejection of the design in favour of the llyushin DB-3.

Once the crew had been trained they started preparing for the non-stop flight. On August 18, 1938, they took off from the Central Airfield at Moscow for another training flight, but at a height of 165ft the aeroplane suddenly jerked down and almost went out of control. After a difficult landing, it became clear that the shortcomings of the first prototype had not been completely rectified. The tail unit had distorted disastrously during takeoff at maximum weight, and the aircraft was no longer airworthy. The technical team therefore began urgent preparation of the third prototype, the last of the three serviceable machines.

The aircraft’s replacement caused deferment of the flight, which in turn led to concern over a successful outcome. Autumn had already set in and weather conditions along the planned route across the Urals and Siberia were deteriorating with each passing day.

The first DB-2B, named Rodina (motherland) was flown to a long-distance women’s record by an all-female crew, covering 5908km on 24/25 September 1938 before making an emergency landing.

Examples survived well into the wartime period, flying for Aeroflot or on research projects.

DB-2bis
Engine: 2 x M-86
Max take-off weight: 12500 kg / 27558 lb
Empty weight: 5855 kg / 12908 lb
Wingspan: 31.0 m / 102 ft 8 in
Length: 15.0 m / 49 ft 3 in
Wing area: 85.0 sq.m / 914.93 sq ft
Max. speed: 300 km/h / 186 mph
Ceiling: 8000 m / 26250 ft
Range w/max.fuel: 7000 km / 4350 miles
Crew: 3

The Tupolev ANT-35 all-metal light passenger transport prototype was based on the SB-2 bomber, and was flown initially on 20 August 1936. Of low-wing configuration with retractable main landing gear units, it was powered by two 597kW Gnome-Rhone 14K radials, later replaced by Soviet M-85s; its near circular-section fuselage accommodated a crew of two or three and 10 passengers. The improved ANT-35bis prototype was followed by nine series aircraft powered by 746kW M-62IR engines, and the type entered service with Aeroflot as the PS-35, delivered from 1937 to 1939. After June 1941 several were used for liaison and VIP transport, this 20.80m span aircraft having a maximum speed of 372km/h and a range of 1640km.

PS-35
Engines: 2 x M-85
Max take-off weight: 6620 kg / 14595 lb
Wingspan: 20.8 m / 68 ft 3 in
Length: 15.0 m / 49 ft 3 in
Height: 5.9 m / 19 ft 4 in
Wing area: 58.0 sq.m / 624.31 sq ft
Max. speed: 376 km/h / 234 mph
Cruise speed: 350 km/h / 217 mph
Ceiling: 7200 m / 23600 ft
Range: 1600 km / 994 miles
Crew: 2
Passengers: 10

A progressive development of the basic ANT-21bis design, the ANT-29 was a DIP (Dvukhmotorny istrebitel pushechny, or twin-engined cannon fighter) designed by Aleksandr Arkhangelski’s brigade. Of flush-riveted all-metal construction and powered by two 760hp Hispano-Suiza 12Ybrs 12-cylinder liquid-cooled engines, the ANT-29 carried a 102mm Kurchevski DRP, a recoilless gun of 4.00m length, the exhaust gases of which were discharged through a steel tube projecting from the rear of the fuselage. This weapon was hand-loaded by the second crew member. In addition, one 20mm cannon was mounted in each wing root and provision was made for a dorsally-mounted 7.62mm machine gun. Priority assigned to other programmes delayed completion, and flight testing of the ANT-29 did not begin until the end of 1935, although the prototype had been rolled out in the previous February. State acceptance testing was scheduled for the first half of 1936, but, in the event, never took place as numerous problems were revealed by factory testing, including serious longitudinal instability. The project was abandoned after a loss of interest in Kurchevski’s recoilless guns for which the ANT-29 had been designed. These had suffered repeated failures leading to Kurchevski’s arrest and subsequent disappearance.

Engines: two 760hp Hispano-Suiza 12Ybrs 12-cylinder
Max take-off weight: 5300 kg / 11685 lb
Empty weight: 3900 kg / 8598 lb
Wingspan: 19.19 m / 63 ft 0 in
Length: 11.65 m / 38 ft 3 in
Max. speed: 352 km/h / 219 mph

Of unconventional design in employing a tandem fore-and-aft engine arrangement and twin tailbooms embodying recoilless gun tubes as integral, but non-load-carrying, structural components, the ANT-23 single-seat fighter was conceived at the AGOS TsAGI by Viktor N Chernyshov, one of Tupolev’s brigade leaders. Of all-metal construction with smooth stressed skinning for the fuselage and wing – the latter and the tail surfaces being strengthened by externally-attached inverted “U” strips – and tail covering, the fighter was powered by two 525hp Gnome-Rhone 9AK nine-cylinder air-cooled radial engines.

Armament consisted of two 76mm Kurchevski APK-4 recoilless weapons which were embodied in the tailbooms, the gun gases being discharged from their tails. Known unofficially as the Baumanskii Komsomolyets – in memory of the pre-revolutionary Communist after whom the district in which the TsAGI was situated was named – and officially as the I-12, the ANT-23 was first flown in late December 1931. Flight testing continued through early 1932, but, on 19 May, the port gun exploded, the tail-boom collapsing on touchdown. The aircraft was overweight and suffered substantially higher drag than had been calculated. Chernyshov and his team were developing a means of jettisoning the aft propeller to afford safe escape for the pilot in an emergency, but, at the beginning of 1933, the ANT-23 was abandoned.

Engines: two 525hp Gnome-Rhone 9AK nine-cylinder air-cooled radial.
Max take-off weight: 2400 kg / 5291 lb
Wingspan: 15.60 m / 51 ft 2 in
Length: 9.50 m / 31 ft 2 in
Wing area: 30.00 sq.m / 322.92 sq ft
Max. speed: 300 km/h / 186 mph
Armament: two 76mm Kurchevski APK-4 recoilless

Designed at the KOSOS (Konstruktorski otdel opytnovo samolyetostroeniya, or Design Department for Experimental Aircraft Construction) within TsAGI by a brigade headed by Aleksandr A Arkhangel’sky, the ANT-21 MI (mnogomestnyi istrebitel – multi-seat fighter) was, by international standards of its day, very much state-of-the-art. Featuring all-metal stressed-skin semi-monocoque construction with partial flush-riveting and a retractable main undercarriage, the ANT-21, which was assigned the service designation MI-3, was powered by two M-17B (BMW VI) 12-cylinder water-cooled engines of 680hp. Proposed armament consisted of one 12.7mm machine gun or 20mm cannon on a pivoted nose mounting, two 7.62mm guns firing from a dorsal position and a single 7.62mm gun firing from a ventral tunnel. Three crew members were carried.

Work on the ANT-21 began on 18 January 1932, first flight taking place in August 1933. On 14 September, the starboard rudder suffered damage and separated as a result of violent flutter in a shallow dive. Arkhangel’sky elected to undertake major redesign as the ANT-21bis.

Retaining the wings, engines and undercarriage of the ANT-21, the ANT-21bis alias MI-3D (the suffix letter indicating dubler, or, literally, “understudy”) mated these elements with an entirely new fuselage, which provided enclosed cockpits for all crew members, and a single fin-and-rudder. Completed in April 1934, the ANT-21bis had provision for the same armament as that of the ANT-21, but the ventral tunnel was omitted, the gun being fired instead through a trap. During initial flight trials some tail oscillation at certain power settings led to the introduction of tailplane bracing struts. State acceptance trials were conducted between July and December 1934, but the results were somewhat academic as there was little official interest in an M-17B-powered aircraft which had, in any case, been largely overtaken by the ANT-29. Consequently, further work on the ANT-21bis was discontined.

ANT-21 / MI-3
Engines: two M-17B (BMW VI) 12-cylinder, 680hp
Max take-off weight: 5500 kg / 12125 lb
Empty weight: 3670 kg / 8091 lb
Wingspan: 20.76 m / 68 ft 1 in
Length: 11.70 m / 38 ft 5 in
Wing area: 55.10 sq.m / 593.09 sq ft
Max. speed: 359 km/h / 223 mph
Range: 1120 km / 696 miles

ANT-21bis / MI-3D
Engines: two M-17B (BMW VI) 12-cylinder, 680hp
Max take-off weight: 5260 kg / 11596 lb
Empty weight: 3800 kg / 8378 lb
Wingspan: 20.76 m / 68 ft 1 in
Length: 12.30 m / 40 ft 4 in
Wing area: 55.10 sq.m / 593.09 sq ft
Max. speed: 356 km/h / 221 mph