Tupolev TB-3

Tupolev TB-3

Company type	Heavy bomber aircraft
Industry	Aviation, Military aviation
Founded	1926
Founder	Andrei Tupolev (design bureau)
Headquarters	Soviet Union , Soviet Union
Products	Heavy bomber aircraft

The Tupolev TB-3, designated as ANT-6 by the design bureau, was a monoplane heavy bomber employed by the Soviet Air Force during the 1930s and into the early phase of World War II. It was among the earliest four-engine heavy bombers featuring cantilever wings.Template:Page needed Although considered outdated and officially withdrawn from frontline service by 1939, the TB-3 continued to operate in bombing and transport roles throughout much of WWII. The aircraft also participated in combat as a fighter mothership under the Zveno project and served as a light tank carrier.

Development

In 1925, the Soviet Air Force issued a requirement to TsAGI for a heavy bomber equipped with engines delivering a combined output of 1,500 kW (2,000 hp), capable of operating on either wheeled or float landing gear. Design work commenced at Tupolev’s OKB in 1926, with final operational specifications established in 1929. The design was based on the earlier Tupolev TB-1, initially powered by 440 kW (590 hp) Curtiss V-1570 "Conqueror" engines, with plans to switch production models to Mikulin M-17 engines (derivatives of the BMW VI). Approval of the mock-up occurred on 21 March 1930, and the first prototype was finalized by 31 October that year. The maiden flight took place on 22 December 1930, piloted by Mikhail Gromov using ski landing gear. Despite nearly losing control due to throttle issues caused by vibration, the flight was deemed successful. On 20 February 1931, mass production of the ANT-6 with M-17 engines received authorization from the Soviet Air Force.

The prototype underwent modifications replacing its original engines with 540 kW (720 hp) BMW VIz 500 units, incorporating larger radiators and wooden fixed-pitch propellers designed by TsAGI. The initial single-wheel landing gear proved inadequate and was substituted with tandem bogies fitted with 1,350 mm × 300 mm (53 in × 12 in) tires. The first pre-production model TB-3 4M-17 took flight on 4 January 1932, piloted by Andrey Yumashev and I. F. Petrov. Unexpectedly, production aircraft were found to be approximately 10–12% heavier than prototypes, which notably degraded performance. This weight increase stemmed from manufacturing tolerances allowing thicker steel sheets, pipes, and wiring than those used in prototypes. Additionally, production models featured a heavier coating of camouflage paint and lacquer. To address this, factories incentivized workers with payments of 100 roubles per kilogram saved. Combined with efforts from Tupolev’s OKB, these measures reduced weight by nearly 1,000 kg (2,200 lb); nonetheless, individual aircraft weights could still vary by several hundred kilograms.

In 1933, a single TB-3 4M-17F was aerodynamically refined by removing turrets and bomb racks, sealing all openings, and fitting wheel fairings. This modification resulted in only a modest increase of about 4.5% in maximum speed and a similar range improvement. Tupolev concluded that streamlining offered limited benefits for large, slow bombers. To evaluate corrugated skin effects, between January and February 1935 one TB-3 4AM-34R had its corrugations progressively covered with fabric, yielding a top speed increase of 5.5% and enhancing service ceiling by 27.5%. The same aircraft showed notable climb rate improvements when equipped with experimental four-blade propellers.

Record flights

• The TB-3 powered by AM-34R engines achieved an endurance record of 18 hours and 30 minutes.
• Piloted by Andrey Yumashev, the TB-3 equipped with AM-34FRN engines set multiple payload-to-altitude records:
  • On 11 September 1936: lifted 5,000 kg (11,000 lb) to an altitude of 8,116 m (26,627 ft), later improved to 8,980 m (29,460 ft) on 28 October.
  • On 16 September 1936: carried 10,000 kg (22,000 lb) to 6,605 m (21,670 ft).
  • On 20 September 1936: transported 12,000 kg (26,000 lb) to 2,700 m (8,900 ft).

Design

File:Tupolev TB-3 SA-kuva 7361.jpg

TB-3 following an emergency landing during the Winter War in March 1940

The TB-3 featured an all-metal steel airframe, developed by Andrei Tupolev's design bureau, drawing on the all-metal construction techniques pioneered since 1918 by Hugo Junkers. Its structure consisted of V-shaped beams sheathed with non-load-bearing corrugated metal skin varying between 0.3 mm (0.012 in) and 0.8 mm (0.031 in) thickness. The corrugations measured 13 mm (0.51 in) in depth and were spaced 50 mm (1.97 in) apart. The cantilever wing incorporated four tubular-section spars for support. Advancements in stronger steel alloys by 1934 allowed the wingspan to be extended from 39.5 to 41.85 m (129 ft 7 in to 137 ft 4 in), while the wing surface area increased slightly from 230 to 234.5 m² (2,476 to 2,524 sq ft). The aircraft's skin was durable enough to be walked upon in soft footwear without damage, and the wings’ leading edges could be lowered to serve as maintenance walkways for the engines. Control surfaces were operated via cables, featuring a variable-incidence tailplane and a trim system to compensate for asymmetric thrust if an engine failed on one side. The fixed main landing gear lacked braking systems. Fuel tanks were not equipped with fire or leak protection, although the engines were fitted with internal fire suppression mechanisms. The M-17 powerplants were calibrated to achieve a theoretical maximum range of 3,250 km (1,750 nmi; 2,020 mi) without encountering spark plug or carburetor fouling issues. Defensive weaponry comprised light machine guns mounted in five turrets: one located in the nose, two atop the mid-fuselage, and a retractable "dustbin" turret beneath each wing between engine nacelles. Later models repositioned one of the upper fuselage turrets behind the tail fin.

Operational history

File:TB-3 paratroops.jpg

Soviet paratroopers boarding a TB-3 transport

File:T-27 tb-3.jpg

TB-3 transporting a T-27 tankette

File:ANT-6A Glavsevmorput.jpg

Tupolev ANT-6A operated by the Soviet agency Glavsevmorput (GUSMP)

The TB-3 saw active deployment during the Battle of Khalkhin Gol against Japanese forces and in the conflict known as the Winter War against Finland. Although officially retired from frontline service by 1939, at the outbreak of the Great Patriotic War on 22 June 1941, the Soviet Air Force maintained 516 operational TB-3s, with an additional 25 assigned to the Soviet Navy. Positioned well away from the western frontier of the USSR, these bombers largely avoided severe losses during initial German air raids. Following this, TB-3 units from the 3rd Heavy Bomber Regiment began conducting night bombing sorties starting 23 June. Due to shortages of combat-ready aircraft, some TB-3s were also deployed during daylight missions without fighter escort; operating at low to medium altitudes under these conditions resulted in significant attrition from enemy fighters and ground fire. By August 1941, TB-3s constituted approximately one-quarter of Soviet bomber strength and, manned by experienced aircrews, were undertaking up to three sorties nightly. The type participated in all major engagements through 1943, including key battles such as Smolensk (1941), Moscow, Stalingrad, Leningrad’s siege, and Kursk. As late as 1 July 1945, ten TB-3s remained active within the 18th Air Army.

In addition to bombing roles, the TB-3 was widely utilized for cargo and paratrooper transport missions, capable of carrying up to 35 troops simultaneously. During the first five months of hostilities, it moved 2,797 t (6,166,000 lb) of supplies and transported 2,300 personnel.

The aircraft also featured in specialized operations as a fighter carrier within the Zveno project, and for deploying light tanks such as the T-27, T-37, and T-38. On 1 August 1941, two TB-3s configured as Zveno-SPB, each carrying two Polikarpov I-16 fighters armed with 250 kg (550 lb) bombs, successfully destroyed an oil depot at Constanța port in Romania without sustaining losses. Subsequently, on 11 and 13 August 1941, Zveno-SPB missions inflicted damage on Romania’s King Carol I Bridge over the Danube River. These Zveno operations ceased by autumn 1942 due to vulnerabilities inherent in using mothership aircraft.

Acknowledging its wartime contributions, three TB-3s were showcased during the inaugural post-war air parade held on 18 June 1945.

Variants

File:Zveno-SPB.jpg

TB-3 4AM-34FRN configured in the Zveno-SPB setup, carrying Polikarpov I-16 fighters equipped with FAB-250 bombs

File:Paratroopers jumping from Tupolev TB-3.jpg

Paratroopers exiting a Tupolev TB-3

Source: Shavrov

TB-3 4M-17F

The initial production model, representing roughly fifty percent of the total TB-3 units manufactured.

TB-3 4M-34

Equipped with Mikulin AM-34 engines featuring updated radiators and additional oil coolers; several dozen were produced.

TB-3 4M-34R

Powered by Mikulin AM-34R engines with reduction gearboxes that considerably enhanced performance; included an extra turret behind the tail fin, tail wheels fitted with hydraulic brakes, aerodynamic improvements at the wing-fuselage junction and radiators, as well as retractable wind generators.

TB-3 4AM-34RD

A series of long-range demonstration aircraft characterized by streamlined fuselages and wheel brakes. Some models had single main wheels measuring 2 m (6 ft 7 in) in diameter and three-blade metal propellers. These aircraft were used for flights to Warsaw, Paris, and Rome during 1933–1934.

TB-3 4AM-34RN

A high-altitude variant featuring AM-34RN engines, four-blade propellers on the inner engines and two-blade on the outer ones, 2 m (6 ft 7 in) single main wheels, upgraded turrets armed with ShKAS machine guns, a maximum speed of 288 km/h (179 mph) at 4,200 m (13,800 ft), and a service ceiling of 7,740 m (25,390 ft). Tested between August and October 1935, but it did not enter mass production as the original TB-3 design was becoming outdated.

TB-3 4AM-34FRN/FRNV

Fitted with AM-34FRN/FRNV engines delivering increased power and four-blade propellers, along with aerodynamic enhancements such as streamlined turrets, 2 m (6 ft 7 in) main wheels equipped with brakes, and a top speed exceeding 300 km/h (190 mph).

TB-3D

A proposed version intended to use Charomsky AN-1 diesel engines rated at 550 kW (740 hp) with an anticipated range of 4,280 km (2,660 mi); however, it never entered production due to inferior overall performance compared to the TB-3 4AM-34RN.

G-2

Decommissioned TB-3 aircraft powered by M-17 and M-34 engines that were converted for cargo transport duties under Aeroflot operation.

ANT-6-4M-34R "Aviaarktika"

A TB-3 modification created for the 1937 North Pole expedition featuring an enclosed cockpit, single 2 m (6 ft 7 in) main wheels, and three-blade metal propellers.

Operators

Template:Flagcountry

• Chinese Nationalist Air Force

Template:USSR

• Aeroflot
• Soviet Air Force
• Soviet Naval Aviation

Accidents and incidents

17 March 1938

A Polyarnaya Aviatsiya G-2 (CCCP-N210) crashed during landing at Bukhta Teplits after ground fog forced a go-around maneuver. Due to inadequate crew resource management, the crew re-entered the fog bank. The aircraft descended until its left landing ski contacted snow, tearing off the landing gear and causing a crash. All seven occupants survived, but the aircraft was written off.

14 March 1941

An Aeroflot G-2 (CCCP-L1496) stalled and crashed near Begovat, Uzbekistan after the pilot attempted to climb following altitude loss caused by severe turbulence. The accident resulted in six crew fatalities. The flight was operating a Tashkent–Fergana cargo route.

27 August 1941

An Aeroflot G-2 (CCCP-L1996) collided with terrain near Kizyl-Arvat, Turkmenistan while attempting an emergency landing after failing to locate its destination. Six of nine aboard perished. The aircraft was on a Tashkent–Ashgabat cargo service.

26 December 1941

An Aeroflot G-2 (CCCP-L3043) crashed near Dmitriyevka (present-day Bayserke), Kazakhstan after losing altitude during a turn. Twenty-six of thirty-four passengers died. The flight was operating an Alma-Ata (now Almaty)–Karaganda–Kazan passenger service carrying senior Kazakh party and government officials. This incident is the deadliest involving a G-2.

29 December 1941

An Aeroflot G-2 (CCCP-L2010) crashed into the Amu Darya River close to Chardzhou Airport following rapid altitude loss caused by pilot spatial disorientation. Seven of thirty-six on board were killed. The aircraft was conducting a Chardzhou–Urgench passenger flight.

Specifications (TB-3 4M-17F, 1934 version)

File:Tupolev TB-3 3-view line drawing.svg

Tupolev TB-3

References

Bibliography

• Duffy, Paul and Andrei Kandalov. Tupolev: The Man and His Aircraft. Shrewsbury, UK:Airlife Publishing, 1996. ISBN 1-85310-728-X.
• Gordon, Yefim and Vladimir Rigmant. OKB Tupolev: A History of the Design Bureau and its Aircraft. Hinckley, Leicestershire, UK: Midland Counties Publishing, 2005. ISBN 1-85780-214-4.
• Gunston, Bill. The Osprey Encyclopedia of Russian Aircraft from 1875 – 1995. London: Osprey Aerospace, 1995. ISBN 1-85532-405-9.
• Kulikov Victor and Michael C. Masslov. Les Bombardiers Quadrimoteurs Sovjetiques Tupolev TB3 & Petkyakov PE8 (French). Outreau, France: Lela Presse, 2001. ISBN 2-914017-05-7.
• Shavrov V.B. Istoriia konstruktskii samoletov v SSSR do 1938 g. (3 izd.). Mashinostroenie, 1985. ISBN 5-217-03112-3.