Tupolev SB
Encyclopedia
The Tupolev
Tupolev
Tupolev is a Russian aerospace and defence company, headquartered in Basmanny District, Central Administrative Okrug, Moscow. Known officially as Public Stock Company Tupolev, it is the successor of the Tupolev OKB or Tupolev Design Bureau headed by the Soviet aerospace engineer A.N. Tupolev...

 ANT-40, also known by its service name Tupolev SB ( - Skorostnoi Bombardirovschik - "high speed bomber"), and development co-name TsAGI-40, was a high speed twin-engined three-seat monoplane
Monoplane
A monoplane is a fixed-wing aircraft with one main set of wing surfaces, in contrast to a biplane or triplane. Since the late 1930s it has been the most common form for a fixed wing aircraft.-Types of monoplane:...

 bomber
Bomber
A bomber is a military aircraft designed to attack ground and sea targets, by dropping bombs on them, or – in recent years – by launching cruise missiles at them.-Classifications of bombers:...

, first flown in 1934
1934 in aviation
This is a list of aviation-related events from 1934:-Events:* Sir Alan Cobhams Flight Refuelling Ltd. develops the looped-hose aerial refueling system, a weighted cable let out of a tanker aircraft and grabbed by a grapnel fired from the receiving aircraft...

.

The design was very advanced, but lacked refinement, much to the dismay of crews and maintenance personnel - and of Stalin
Joseph Stalin
Joseph Vissarionovich Stalin was the Premier of the Soviet Union from 6 May 1941 to 5 March 1953. He was among the Bolshevik revolutionaries who brought about the October Revolution and had held the position of first General Secretary of the Communist Party of the Soviet Union's Central Committee...

, who pointed out that "there are no trivialities in aviation".

Numerically the most important bomber in the world in the late 1930s, the SB was the first modern stressed-skin
Monocoque
Monocoque is a construction technique that supports structural load by using an object's external skin, as opposed to using an internal frame or truss that is then covered with a non-load-bearing skin or coachwork...

 aircraft produced in quantity in the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 and probably the most formidable bomber of the mid-1930s. Many versions saw extensive action in Spain
Spanish Civil War
The Spanish Civil WarAlso known as The Crusade among Nationalists, the Fourth Carlist War among Carlists, and The Rebellion or Uprising among Republicans. was a major conflict fought in Spain from 17 July 1936 to 1 April 1939...

, the Republic of China
Second Sino-Japanese War
The Second Sino-Japanese War was a military conflict fought primarily between the Republic of China and the Empire of Japan. From 1937 to 1941, China fought Japan with some economic help from Germany , the Soviet Union and the United States...

, Mongolia
Mongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...

, Finland
Winter War
The Winter War was a military conflict between the Soviet Union and Finland. It began with a Soviet offensive on 30 November 1939 – three months after the start of World War II and the Soviet invasion of Poland – and ended on 13 March 1940 with the Moscow Peace Treaty...

 and at the beginning of the War
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 against Germany
Nazi Germany
Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...

 in 1941. It was also used in various duties in civil variants, as trainers
Trainer (aircraft)
A trainer is a class of aircraft designed specifically to facilitate in-flight training of pilots and aircrews. The use of a dedicated trainer aircraft with additional safety features—such as tandem flight controls, forgiving flight characteristics and a simplified cockpit arrangement—allows...

 and in many secondary roles.

Successful in the Spanish Civil War because it outpaced most fighters
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...

, the aircraft was obsolete by 1941
1941 in aviation
This is a list of aviation-related events from 1941:- Events :* Jackie Cochran became the first woman to fly a bomber across the Atlantic Ocean.* During the spring and summer, the Imperial Japanese Navys air arm conducts Operation 102, its second major bombing campaign against Chungking.* By early...

. By June 1941, 94% of bombers in the Red Army air force (VVS
VVS
VVS is a three letter acronym which may refer to:* Very Very Slightly Included, a way of describing the clarity of a diamond* Vulvar vestibulitis syndrome, a syndrome of vulvodynia associated with chronic disease* V. V. S...

 RKKA) were SBs.

Development

In 1933 the Soviet Air Force ministry (UVVS) issued an outline requirement for a high-speed bomber. Work on this proposal at TsAGI
TsAGI
TsAGI is a transliteration of the Russian abbreviation for Центра́льный аэрогидродинами́ческий институ́т or "Tsentralniy Aerogidrodinamicheskiy Institut", the Central Aerohydrodynamic Institute....

 began in January 1934. The SB was designed and developed in the Tupolev KB ("Design Bureau") by a team led by A. A. Arkhangelski. Two versions were planned - with Wright Cyclone
Wright R-1820
|-See also:-References:* Bridgman, L, Jane's Fighting Aircraft of World War II. Crescent. ISBN 0-517-67964-7* Eden, Paul & Soph Moeng, The Complete Encyclopedia of World Aircraft. Amber Books Ltd. Bradley's Close, 74-77 White Lion Street, London, NI 9PF, 2002, ISBN 0-7607-3432-1), 1152...

 radial engines (ANT-40 RTs), and with the Hispano-Suiza 12Y
Hispano-Suiza 12Y
The Hispano-Suiza 12Y was a French aircraft engine in the pre-WWII era. Developed from the earlier, and somewhat smaller, 12X, the 12Y became the primary 1,000 hp class engine and was used in a number of famous aircraft, including the Morane-Saulnier M.S.406 and Dewoitine D.520...

 liquid-cooled V12 engine
V12 engine
A V12 engine is a V engine with 12 cylinders mounted on the crankcase in two banks of six cylinders, usually but not always at a 60° angle to each other, with all 12 pistons driving a common crankshaft....

s (ANT-40 IS). The skills gained in the design of the MI-3
Tupolev ANT-21
-References:* Duffy, Paul and Andrei Kandalov. Tupolev The Man and His Aircraft. Shrewsbury, UK:Airlife Publishing, 1996. ISBN 1 85310 728 X.* Green, William and Gordon Swanborough. The Complete Book of Fighters. New York, Smithmark, 1994. ISBN 0-8317-3939-8.* Gunston, Bill. The Osprey Encyclopedia...

 and DI-8 aircraft were widely used. The first two prototype
Prototype
A prototype is an early sample or model built to test a concept or process or to act as a thing to be replicated or learned from.The word prototype derives from the Greek πρωτότυπον , "primitive form", neutral of πρωτότυπος , "original, primitive", from πρῶτος , "first" and τύπος ,...

s were designed as ANT-40.1 and ANT-40.2. The Cyclone powered prototype flew first, on 7 October 1934, with the first Hispano-Suiza powered prototype (ANT-401), which featured a larger wing, flew on 30 December 1934, demonstrating superior performance.

The second Hispano-Suiza powered aircraft, the ANT-402 was considered a production prototype, and its performance was impressive. It was however plagued by teething problems, leading unhappy test personnel to cover the ANT-402 with placards listing the aircraft's defects prior to a visit by Sergo Ordzhonikidze
Grigoriy Ordzhonikidze
Grigol Ordzhonikidze ორჯონიკიძე - Grigol Orjonikidze, , generally known as Sergo Ordzhonikidze ; – February 18, 1937) was a Georgian Bolshevik, later member of the CPSU Politburo and close friend to Joseph Stalin...

, the Commissar for Heavy Industry. On seeing these placards, Ordzhonikidze summoned Tupolev to a meeting at the Kremlin
Kremlin
A kremlin , same root as in kremen is a major fortified central complex found in historic Russian cities. This word is often used to refer to the best-known one, the Moscow Kremlin, or metonymically to the government that is based there...

 to discuss these shortfalls. When Tupolev stated that most of the defects were trivial. On hearing this, Joseph Stalin
Joseph Stalin
Joseph Vissarionovich Stalin was the Premier of the Soviet Union from 6 May 1941 to 5 March 1953. He was among the Bolshevik revolutionaries who brought about the October Revolution and had held the position of first General Secretary of the Communist Party of the Soviet Union's Central Committee...

 said:

The first production aircraft, designated SB, rolled off the production line before the end of 1935, and before ANT-402 had completed its flight test programme. The aircraft entered full production in 1936
1936 in aviation
This is a list of aviation-related events from 1936:- Events :* The Royal Air Forces first monoplane bomber, the Avro Anson, enters service.*The German Luftwaffe begins experiments with helle Nachtjagd techniques, the operation of night fighters with the aid of searchlights.*The Soviet aviator...

, and was produced in two plants, State Aircraft Factory No 22 at Moscow and No 125 at Irkutsk
Irkutsk
Irkutsk is a city and the administrative center of Irkutsk Oblast, Russia, one of the largest cities in Siberia. Population: .-History:In 1652, Ivan Pokhabov built a zimovye near the site of Irkutsk for gold trading and for the collection of fur taxes from the Buryats. In 1661, Yakov Pokhabov...

 until 1941.

Despite the fact that the assembly lines were plagued with a constant string of modifications, some 400 SBs were delivered by the end of 1936 - a number of these being diverted to Spain - and 24 VVS squadrons were in the process of working up with the new bomber. Giving excellent performance in the Spanish Civil War, it acquired the popular name "Katyusha" (Catherine).

In 1937, negotiations were successfully concluded between the Soviet and Czechoslovak governments for the supply of SB bombers and a licence for local production in exchange for the right to produce the Skoda 75 mm Model 1936
Skoda 75 mm Model 1936
The Skoda 75 mm Model 1936 was a mountain gun manufactured by Skoda Works, in Czechoslovakia, and a variant was produced in Russia . Skoda also produced a handful of the 76.2 mm variant. For transport, the gun could be broken down into 3 sections, and further broken down into ten loads...

 mountain gun
Mountain gun
Mountain guns are artillery pieces designed for use in mountain warfare and areas where usual wheeled transport is not possible. They are similar to infantry support guns, and are generally capable of being broken down into smaller loads .Due to their ability to be broken down into smaller...

. The version of the SB to be supplied to , and subsequently license-built as the Avia B-71 was fundamentally the SB 2M-100A but fitted with the Avia-built Hispano-Suiza 12-Ydrs engine. A single 7.92 mm ZB-30
ZB-30
The ZB-30 and ZB-30J were the later versions of the famous Czechoslovak machine gun, the ZB-26. However, the ZB-30 had some design differences, making it similar to the later ZGB-33, which was put into production as the Bren gun...

 machine gun
Machine gun
A machine gun is a fully automatic mounted or portable firearm, usually designed to fire rounds in quick succession from an ammunition belt or large-capacity magazine, typically at a rate of several hundred rounds per minute....

 supplanted the twin ShKAS machine guns in the nose and similar weapons were provided for the dorsal and ventral stations.

Sixty aircraft were to be flown to Czechoslovakia by mid-1938. The planned licensed production program took a decidedly leisurely course, despite the increasingly dangerous political situation. By 15 March 1939, when the German Wehrmacht
Wehrmacht
The Wehrmacht – from , to defend and , the might/power) were the unified armed forces of Nazi Germany from 1935 to 1945. It consisted of the Heer , the Kriegsmarine and the Luftwaffe .-Origin and use of the term:...

 occupied Bohemia and Moravia, not one Czech-built aircraft had been delivered.
Development of the SB continued, meanwhile, with revisions being made to reflect the lessons of early operations in Spain. As problems were encountered in converting pilots to fly the SB, a trainer version, the USB was built in September 1937, with a modified nose with an open cockpit for an instructor and dual controls. Problems were also encountered with the aircraft's armament, with the nose guns having limited traverse and so being little use against head-on attacks. Later aircraft were modified with a better field of fire. From 1940 the dorsal gun position was replaced by an enclosed turret, while the ventral gun position, which was difficult to use effectively, was also modified.

The aircraft was also progressively fitted with improved engines. At first it was equipped with the Klimov M-100, a license-built version of the Hispano-Suiza 12Ybrs engine, but this was soon replaced by the more powerful M-100A, and from 1938 by the yet more powerful M-103. While the engine installation of the SB 2-M103 initially retained the drag inducing frontal radiators of the M-100 powered aircraft, an improved engine installation was developed with the radiators slung under the engines. On 2 September 1937 M.Yu. Alexeev set an official altitude record of 12246 m (40,177.2 ft) with load of 1000 kg (2,204.6 lb) in an M-103 powered SB. He had earlier set an unofficial record of 12695 m (41,650.3 ft).

In an attempt to further improve the performance of the SB, which by 1939 was becoming obsolete, the development of two second-generation versions were authorised, a direct replacement for the SB and a specialised dive bomber. The level bomber, known as the SN-MN or MMN, had a new wing of reduced wing area and was powered by more powerful Klimov M-105
Klimov M-105
-See also:-External links:*...

 engines. Performance was little better than the standard aircraft, however, and it was abandoned. The dive-bomber, designated SB-RK (later redesignated Arkhangelsky Ar-2
Arkhangelsky Ar-2
|-See also:-References:* *...

 after its designer, with Tupolev having been imprisoned and being in disgrace) was similar to the MMN but was fitted with dive brakes. Testing was successful, and it was ordered into production.

Even though the SB was no longer a state of the art aircraft, production continued to increase through 1939 and 1940, as the Soviet Union tried to build up the strength of their air forces to compete with the growing threat of Nazi Germany, with almost 4,000 being built in these two years. The SB was phased out of production in early 1941, being replaced by the Petlyakov Pe-2
Petlyakov Pe-2
The Petlyakov Pe-2 was a Soviet dive bomber aircraft used during World War II. It was regarded as one of the best ground attack aircraft of the war and it was extremely successful in the roles of heavy fighter, reconnaissance and night fighter...

. A total of 5,695 were built at Factory No 22 at Moscow before it was evacuated to Kazan
Kazan
Kazan is the capital and largest city of the Republic of Tatarstan, Russia. With a population of 1,143,546 , it is the eighth most populous city in Russia. Kazan lies at the confluence of the Volga and Kazanka Rivers in European Russia. In April 2009, the Russian Patent Office granted Kazan the...

, while Factory No 125 built a further 1,136 at Irktusk. Three prototypes were built at the Tupolev design bureau, while Aero Vodochody
Aero Vodochody
Aero Vodochody is a Czech aircraft company, active from 1919, notable for producing the L-29 Delfin, L-39 Albatros, L-59 Super Albatros and the L-159 Alca....

 and Avia
Avia
Avia is a Czech aircraft and automotive company notable for producing biplane fighter aircraft, especially the B-534, and trucks.- History :...

 in Czechoslovakia built 45 and 66 respectively, giving a total of 6,945 built.

Design

The SB was an all-metal
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 monoplane
Monoplane
A monoplane is a fixed-wing aircraft with one main set of wing surfaces, in contrast to a biplane or triplane. Since the late 1930s it has been the most common form for a fixed wing aircraft.-Types of monoplane:...

 powered by two Klimov M-100 12-cylinder water-cooled
Liquid cooling
Liquid cooling may refer to:* The cooling of a liquid.* The cooling of machinery or devices by convection or circulation of coolants* Liquid Cooling and Ventilation Garment, a garment worn by astronauts.* Liquid metal cooled reactor...

 engines (license production version of Hispano-Suiza 12-Yrds engine) which drove fixed-pitch two-bladed metal
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 propeller
Propeller (aircraft)
Aircraft propellers or airscrews convert rotary motion from piston engines or turboprops to provide propulsive force. They may be fixed or variable pitch. Early aircraft propellers were carved by hand from solid or laminated wood with later propellers being constructed from metal...

s. The engines were provided with honeycomb-type
Honeycomb (geometry)
In geometry, a honeycomb is a space filling or close packing of polyhedral or higher-dimensional cells, so that there are no gaps. It is an example of the more general mathematical tiling or tessellation in any number of dimensions....

 frontal radiator
Radiator
Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics...

s enclosed by vertical thermostat
Thermostat
A thermostat is the component of a control system which regulates the temperature of a system so that the system's temperature is maintained near a desired setpoint temperature. The thermostat does this by switching heating or cooling devices on or off, or regulating the flow of a heat transfer...

-controlled cooling shutters
Louver
A louver or louvre , from the French l'ouvert; "the open one") is a window, blind or shutter with horizontal slats that are angled to admit light and air, but to keep out rain, direct sunshine, and noise...

. At an early production stage, the M-100 engine gave place to an improved M-100A engine, driving ground-adjustable three-pitch propellers, with speed being boosted to 423 km/h (262.8 mph) at 4000 m (13,123.4 ft).
Because of its broad, high aspect ratio wing, that gave it a good altitude performance - Russian crews nicknamed the SB the "Pterodactyl".

Operational history

There were a number of foreign customers for the SB-2. They were mostly satisfied with the aircraft's performance. There were some complaints about the high noise level, cramped crew compartments, hard undercarriage suspension and in particular about the front gunner's position, that could be reached only through an hatch under the fuselage. Consequently, in case of a ditching or belly landing, the gunner could not escape.

Spanish Civil War

While only 54 SBs had been delivered to the Soviet Air Forces by 1 July 1936, this did not stop the new Tupolev bomber being amongst the first shipments of military equipment sent by the Soviet Union to support the Spanish Republicans when the Spanish Civil War
Spanish Civil War
The Spanish Civil WarAlso known as The Crusade among Nationalists, the Fourth Carlist War among Carlists, and The Rebellion or Uprising among Republicans. was a major conflict fought in Spain from 17 July 1936 to 1 April 1939...

 broke out on 17 July 1936. An initial batch of 31 SBs arrived in Cartagena
Cartagena, Spain
Cartagena is a Spanish city and a major naval station located in the Region of Murcia, by the Mediterranean coast, south-eastern Spain. As of January 2011, it has a population of 218,210 inhabitants being the Region’s second largest municipality and the country’s 6th non-Province capital...

 aboard the Soviet Freighter Komsomol in October 1936, flying their first mission, a bombing raid by four SBs against Tablada airfield, Seville
Seville
Seville is the artistic, historic, cultural, and financial capital of southern Spain. It is the capital of the autonomous community of Andalusia and of the province of Seville. It is situated on the plain of the River Guadalquivir, with an average elevation of above sea level...

 on 28 October. The SBs were used to equip Grupo 12 of the Spanish Republican Air Force
Spanish Republican Air Force
The Spanish Republican Air Force, , was the air arm of the Second Spanish Republic, the legally established government of Spain between 1931 and 1939...

, which at first was mainly manned by Soviet volunteers and under Soviet control.

The SB could outpace the Fiat CR.32
Fiat CR.32
The Fiat CR.32 was an Italian biplane fighter used in the Spanish Civil War and World War II. This nimble little Fiat was compact, robust and highly manoeuvrable and gave impressive displays all over Europe in the hands of the Pattuglie Acrobatiche. The CR.32 fought in North and East Africa, in...

 and Heinkel He 51
Heinkel He 51
-See also:-References:NotesBibliography* Donald, David, ed. Warplanes of the Luftwaffe. London: Aerospace, 1994. ISBN 1-874023-56-5.* Green, William and Gordon Swanborough. "The Cadre Creator...Heinkel's Last Fighting Biplane". Air Enthusiast No. 36, May-August 1988. pp. 11–24. ISSN 0143-5450.*...

 biplane
Biplane
A biplane is a fixed-wing aircraft with two superimposed main wings. The Wright brothers' Wright Flyer used a biplane design, as did most aircraft in the early years of aviation. While a biplane wing structure has a structural advantage, it produces more drag than a similar monoplane wing...

 fighters of the nationalist forces, and was therefore difficult to intercept, with dives from high altitude being the only way to intercept the SB. On 29 May 1937 two SBs attacked the German pocket battleship Deutschland
German pocket battleship Deutschland
Deutschland was the lead ship of her class of heavy cruisers which served with the Kriegsmarine of Nazi Germany during World War II. Ordered by the Weimar government for the Reichsmarine, she was laid down at the Deutsche Werke shipyard in Kiel in February 1929 and completed by April 1933...

, mistaking it for the Nationalist cruiser Canarias
Spanish cruiser Canarias
The Canarias was a heavy cruiser of the Spanish Navy. She was designed in the United Kingdom and was a modified version of the Royal Navy's County class cruiser. She was built in Spain by the Vickers-Armstrongs subsidiary Sociedad Española de Construcción Naval...

, killing 31 and injuring a further 83 German sailors. In June–July, a second consignment of 31 SBs were received, allowing Grupo 12 to return to full strength, and a new unit, Grupo 24, to be established. The delivery of Messerschmitt Bf 109
Messerschmitt Bf 109
The Messerschmitt Bf 109, often called Me 109, was a German World War II fighter aircraft designed by Willy Messerschmitt and Robert Lusser during the early to mid 1930s...

s to re-equip the German Condor Legion
Condor Legion
The Condor Legion was a unit composed of volunteers from the German Air Force and from the German Army which served with the Nationalists during the Spanish Civil War of July 1936 to March 1939. The Condor Legion developed methods of terror bombing which were used widely in the Second World War...

 meant that the SB could no longer evade Nationalist fighters by sheer speed, and losses rose.

A third and final batch of 31 SBs arrived in June 1938, allowing operations to continue, although losses continued to be high. By the time the Civil War ended in March 1939, 73 SBs had been lost, 40 of them to enemy action. Nineteen SBs were taken over by the Nationalists, and used to form a bomber squadron. Although some were re-engined with French Hispano-Suiza 12Y
Hispano-Suiza 12Y
The Hispano-Suiza 12Y was a French aircraft engine in the pre-WWII era. Developed from the earlier, and somewhat smaller, 12X, the 12Y became the primary 1,000 hp class engine and was used in a number of famous aircraft, including the Morane-Saulnier M.S.406 and Dewoitine D.520...

brs engines to aid maintenance, they were still subject to spares shortages, and in April 1943 only three were airworthy. When Junkers Ju 88
Junkers Ju 88
The Junkers Ju 88 was a World War II German Luftwaffe twin-engine, multi-role aircraft. Designed by Hugo Junkers' company through the services of two American aviation engineers in the mid-1930s, it suffered from a number of technical problems during the later stages of its development and early...

s were received in December 1943, the remaining SBs were used for occasional training flights until withdrawn and scrapped in 1948.

China

In July 1937, the Second Sino-Japanese War
Second Sino-Japanese War
The Second Sino-Japanese War was a military conflict fought primarily between the Republic of China and the Empire of Japan. From 1937 to 1941, China fought Japan with some economic help from Germany , the Soviet Union and the United States...

 broke out. The Soviet Union signed the Sino-Soviet Non-Aggression Pact on 21 August 1937, and as part of this agreement, supplied large amounts of military equipment to the Chinese Nationalists
Republic of China
The Republic of China , commonly known as Taiwan , is a unitary sovereign state located in East Asia. Originally based in mainland China, the Republic of China currently governs the island of Taiwan , which forms over 99% of its current territory, as well as Penghu, Kinmen, Matsu and other minor...

, as well as deploying complete air force units, nominally manned by Soviet volunteers. An initial delivery of 62 SBs was made in September–October 1937, with combat operations by Soviet forces starting in December with attacks on Japanese ships on the Yangtze River
Yangtze River
The Yangtze, Yangzi or Cháng Jiāng is the longest river in Asia, and the third-longest in the world. It flows for from the glaciers on the Tibetan Plateau in Qinghai eastward across southwest, central and eastern China before emptying into the East China Sea at Shanghai. It is also one of the...

. On 23 February 1938, to celebrate Soviet Army Day
Soviet Army Day
Soviet Army Day was a holiday every February 23 in the Soviet Union from 1945 until its breakup. It commemorated the army of the Soviet Union. Before end of WWII, it was called Red Army Day. It is the counterpart of International Women's Day on March 8, which celebrates women. It has now been...

, Soviet SBs carried out a long range attack on Japanese airfields on Taiwan, claiming 40 Japanese aircraft destroyed on the ground.

A further 60 SBs were delivered to China in early 1938, these being heavily used to attack Japanese forces during the Battle of Wuhan
Battle of Wuhan
The Battle of Wuhan, popularly known to the Chinese as the Defence of Wuhan, and to the Japanese as the Capture of Wuhan, was a large-scale battle of the Second Sino-Japanese War...

. Losses were heavy, forcing the Chinese SB units to be temporarily withdrawn from combat. The Soviet units operating the SB over China re-equipped with the Ilyushin DB-3
Ilyushin DB-3
The Ilyushin DB-3 was a Soviet bomber aircraft of World War II. It was a twin-engined, low-wing monoplane that first flew in 1935. It was the precursor of the Ilyushin Il-4...

 in 1939, allowing their SBs to be transferred to Chinese units, but the Chinese made limited use of these reinforcements.

The Soviet Union supplied a further 100 SBs in 1941, just before it signed the Soviet–Japanese Neutrality Pact. The SB was gradually phased out of front-line operations against the Japanese with the delivery of more modern American bombers from 1942, being partly replaced by Lockheed Hudson
Lockheed Hudson
The Lockheed Hudson was an American-built light bomber and coastal reconnaissance aircraft built initially for the Royal Air Force shortly before the outbreak of the Second World War and primarily operated by the RAF thereafter...

s and B-25 Mitchell
B-25 Mitchell
The North American B-25 Mitchell was an American twin-engined medium bomber manufactured by North American Aviation. It was used by many Allied air forces, in every theater of World War II, as well as many other air forces after the war ended, and saw service across four decades.The B-25 was named...

s. Limited numbers of SBs continued in non-combat use, including operations against opium
Opium
Opium is the dried latex obtained from the opium poppy . Opium contains up to 12% morphine, an alkaloid, which is frequently processed chemically to produce heroin for the illegal drug trade. The latex also includes codeine and non-narcotic alkaloids such as papaverine, thebaine and noscapine...

 plantations, before being used against the Communists when the Chinese Civil War
Chinese Civil War
The Chinese Civil War was a civil war fought between the Kuomintang , the governing party of the Republic of China, and the Communist Party of China , for the control of China which eventually led to China's division into two Chinas, Republic of China and People's Republic of...

 flared up in 1945, being finally withdrawn in 1946.

Mongolia

As well as the aircraft operated by volunteers against the Japanese over China, SBs were used in combat against the Japanese during the Fighting near Lake Khasan
Battle of Lake Khasan
The Battle of Lake Khasan and also known as the Changkufeng Incident in China and Japan, was an attempted military incursion of Manchukuo into the territory claimed by the Soviet Union...

 on the border between the Soviet Union and Manchuria
Manchuria
Manchuria is a historical name given to a large geographic region in northeast Asia. Depending on the definition of its extent, Manchuria usually falls entirely within the People's Republic of China, or is sometimes divided between China and Russia. The region is commonly referred to as Northeast...

 in July–August 1938, one SB being lost. Fighting between Soviet and Japanese forces broke out again at Khalkhin Gol in Eastern Mongolia in May 1939. While SBs were not involved in the May air battles, where the Soviet forces received heavy losses, two Regiments of SBs were deployed to Mongolia in June, flying their first missions on 26 June. SBs were used heavily against Japanese forces when they attacked in early July. The Soviet SB regiments consisted of a mixture of early and later SBs, whose differing speeds caused problems in maintaining formation, while Japanese Nakajima Ki-27
Nakajima Ki-27
The was the main fighter aircraft used by the Imperial Japanese Army Air Force up until 1940. Its Allied nickname was "Nate", although it was called "Abdul" in the "China Burma India" theater by many post war sources; Allied Intelligence had reserved that name for the nonexistent Mitsubishi Navy...

 fighters proved adept in exploiting the poor defensive armament of the SB, with the radio operator operating both the dorsal and ventral guns. To minimise losses to Japanese fighters, the Soviets changed tactics, flying SB missions at over 6,100 m (20,000 ft) where it was difficult for the Japanese to intercept. SBs continued to be used against the Japanese as the Soviets and Mongolian forces commanded by Georgy Zhukov
Georgy Zhukov
Marshal of the Soviet Union Georgy Konstantinovich Zhukov , was a Russian career officer in the Red Army who, in the course of World War II, played a pivotal role in leading the Red Army through much of Eastern Europe to liberate the Soviet Union and other nations from the Axis Powers' occupation...

 carried out a successful offensive until a cease-fire was signed in September 1939.

Winter War

On 30 November 1939, the Soviet Union attacked Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

 in the conflict that became known as the Winter War
Winter War
The Winter War was a military conflict between the Soviet Union and Finland. It began with a Soviet offensive on 30 November 1939 – three months after the start of World War II and the Soviet invasion of Poland – and ended on 13 March 1940 with the Moscow Peace Treaty...

, with the forces deployed against Finland including several hundred SBs. Losses were heavy, with bomber formations often un-escorted, and forced to operate at low level, where they were vulnerable to Finnish anti-aircraft
Anti-aircraft warfare
NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...

 fire and fighters. While in 1936 in Spain, the SB could outpace enemy fighters, by now it was vulnerable and poorly armed. SBs were fitted skis for operation from snow covered airfields, slowing the aircraft and making them more vulnerable, while the need to wear heavy winter clothing made the gunner's job even harder. By the end of the 15 week war, at least 100 SBs had been lost, with the Finns claiming nearly 200 shot down, 92 of them to Finnish fighters.

Great Patriotic War

In June 1941, when Germany invaded the Soviet Union
Operation Barbarossa
Operation Barbarossa was the code name for Germany's invasion of the Soviet Union during World War II that began on 22 June 1941. Over 4.5 million troops of the Axis powers invaded the USSR along a front., the largest invasion in the history of warfare...

, while re-equipment with more modern aircraft such as the Pe-2 had begun, 94% of the Soviet operational bomber force was equipped with SBs, with 1,500–2,000 SBs deployed along the Western border districts of the Soviet Union. The Luftwaffe
Luftwaffe
Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....

 started Operation Barbarossa with co-ordinated strikes against 66 major Soviet airfields, (described as "Infanticide" by one Luftwaffe general, so one-sided was the fighting), destroying a large proportion of Soviet air strength on the ground or in the air on the first day of the invasion. The SBs that survived the carnage of the first day continued to be poorly used, many being frittered away in unescorted low-level attacks against German tanks, where the SB's relatively large size and lack of armour made it highly vulnerable to German light Flak, while German fighters continued to take a heavy toll. Within a few days, losses forced most of the remaining SBs to switch to night attacks.

SBs continued to be used, mainly at night, in the defence of Leningrad
Siege of Leningrad
The Siege of Leningrad, also known as the Leningrad Blockade was a prolonged military operation resulting from the failure of the German Army Group North to capture Leningrad, now known as Saint Petersburg, in the Eastern Front theatre of World War II. It started on 8 September 1941, when the last...

, attacking German artillery, and Moscow
Battle of Moscow
The Battle of Moscow is the name given by Soviet historians to two periods of strategically significant fighting on a sector of the Eastern Front during World War II. It took place between October 1941 and January 1942. The Soviet defensive effort frustrated Hitler's attack on Moscow, capital of...

. By December 1941, however, almost all of the SBs had either been replaced or lost, although it remained in large-scale use until March 1942 in the North against Finland. SBs continued in use for non-combat roles such as supply dropping, glider towing and training, while remaining in use in the Far East until 1945.

Finnish use

Many Soviet SBs crashed or force-landed on Finnish soil during the Winter War, with the Finns salvaging as many aircraft as possible, with those in the best condition being sent to Valtion lentokonetehdas
Valtion lentokonetehdas
' was a Finnish aircraft manufacturing company that was founded on 23 February 1928 from the IVL or I.V.L. factory . The company was transferred from being subordinate to the Finnish Air Force to being subordinate to the Ministry of Defence...

 for possible repair for use by the Finnish air force. By the time the Continuation War
Continuation War
The Continuation War was the second of two wars fought between Finland and the Soviet Union during World War II.At the time of the war, the Finnish side used the name to make clear its perceived relationship to the preceding Winter War...

 against the Soviet Union, when Finland moved to recover the territory lost in the Winter War, five SBs had been repaired (with a further three added later), being used to equip Lentolaivue 6
No. 6 Squadron (Finland)
No. 6 Squadron , renamed No. 6 Bomber Squadron was a maritime bomber squadron of the Finnish Air Force during World War II. The squadron was part of Flying Regiment 5....

, flying Maritime patrol and attack missions. These aircraft were supplemented by a further 16 SBs purchased from Germany, who had captured them during the initial weeks of the invasion of the Soviet Union. Finland lost seven SBs to accidents during the Continuation War, with none being lost in combat, with Finnish SBs claiming three Soviet submarines and a 4,000 ton merchant ship sunk.

Variants

  • ANT-38 - Unbuilt 1934 proposal for high speed bomber - possibly related to ANT-41.
  • ANT-40 RTs (Rayt Tsiklon) or SB :first prototype with 545 kW (730 hp) Wright-Cyclone engines and with 19.0 m (62 ft 4 in) wingspan. It was completed in September 1934, making its first flight on 7 October 1934. It was damaged in a forced landing and rebuilt with 670 kW (900 hp) Tumansky M-87 engines, and a second set of test flights were made from 5 February to 31 July 1935. Development not continued as ANT-40 IS was superior. Used as experimental (ski gears, etc.) model.
  • ANT-40 IS (Ispano-Suiza): Prototypes powered by 560 kW (750 hp) Hispano-Suiza 12Y
    Hispano-Suiza 12Y
    The Hispano-Suiza 12Y was a French aircraft engine in the pre-WWII era. Developed from the earlier, and somewhat smaller, 12X, the 12Y became the primary 1,000 hp class engine and was used in a number of famous aircraft, including the Morane-Saulnier M.S.406 and Dewoitine D.520...

     engines, and with longer span (20.3 m (66 ft 7¼ in) wings. Two built, with the first ANT-401 flying on 30 December 1934, reaching 378 km/h (234.9 mph) during initial tests and 402 km/h (250 mph) during later flights. Second example, ANT-402, with modified wings and tail emerged in September 1935 and served as a production prototype.
  • SB 2M-100 - first production model. Wing area increased to 56.7 m2 (610 ft2). Equipped with Klimov M-100 engines (the Hispano-Suiza 12Y built under licence) driving two-bladed propellers.
  • SB 2M-100A - new M-100A engines of 642 kW (860 hp), driving three-bladed propellers. Produced from late 1936. Sometimes unofficially referred to as the SBbis.
  • SB 2M-100A modernizoravannyi - new rear gun installation with MV-3 dorsal turret. Tested in May 1937. Accepted, but no production.
  • SB-bis - prototype powered by 716 kW (960 hp) Klimov M-103
    Klimov M-103
    |-See also:-Bibliography:* Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9...

     engines, dual controls and variable pitch propellers. It flew in September 1937, but increased weight lead to reduced performance.
  • SB-bis2 - M-103 powered prototype with polished wings. Little increase in performance. No production.
  • SB-bis3 - third M-103 powered prototype, with new engine nacelles with radiators relocated under engines rather than the frontal radiators fitted in earlier aircraft. Tested from 1 November 1937-17 January 1938, with testing showing maximum speed increasing to 446 km/h (277 mph). Improvements later incorporated into production aircraft.
  • SB 2M-103 — 10th series. 1938 production version with M-103 engines fitted with original frontal radiators and strengthened structure. Fitted with emergency flight controls for navigator, provision for retractable skis, and for two 368 litre external fuel tanks.
  • SB 2M-103 - 14th series. Late 1939 production, with M-103 engine and revised nacelles and radiators as tested in SBbis3.
  • SB 2M-103 - 18th series. Further improved production version, with fixed radiator intakes and partially polished wings. VISh-22 three-bladed variable-pitch propellers. Fitted with MV-3 dorsal turret.
  • SB 2M-104 — Approximately 30–50 aircraft were completed with M-104 engines, but engine not in series production.
  • SB 2M-106 — A few aircraft completed with M-106 engines, but engine not in production.
  • USB - dual control trainer, with the instructor sitting in an open cockpit in the nose replacing the navigator. Over 120 built, powered by the M-100A or M-103.
  • SB-MN (Men'she nesushchye - reduced area) or MMN (Modifikatsiya men'she nesushchye) — second generation level bomber powered by 783 kW (1,050 hp) M-105 engines and with new wings with NACA 22 high lift airfoil
    Airfoil
    An airfoil or aerofoil is the shape of a wing or blade or sail as seen in cross-section....

    s, reduced wing area and span (18.0 m (59 ft 0¾ in). One built.
  • SB-RK (Rasresnoye krilo - slotted wing) - Dive bomber
    Dive bomber
    A dive bomber is a bomber aircraft that dives directly at its targets in order to provide greater accuracy for the bomb it drops. Diving towards the target reduces the distance the bomb has to fall, which is the primary factor in determining the accuracy of the drop...

     delevloped in parallel with SB-MN. Same wings as SB-MN, but with large slotted flaps usable as dive brakes. The cooling radiators were buried within the wings, with an air intake on the leading and the exhaust on the wing's upper surface. Equipped with three ShKAS machine gun
    ShKAS machine gun
    The ShKAS is a 7.62 mm machine gun widely used by Soviet aircraft in the 1930s and during World War II...

    s, and it could carry six 100 kg (220.5 lb) bombs or two 250 kg (551.2 lb) bombs internally or 1500 kg (3,306.9 lb) bombs externally. Ordered into production as Arkhangelskii Ar-2. 200 built before it was superseded by the Pe-2
    Petlyakov Pe-2
    The Petlyakov Pe-2 was a Soviet dive bomber aircraft used during World War II. It was regarded as one of the best ground attack aircraft of the war and it was extremely successful in the roles of heavy fighter, reconnaissance and night fighter...

     and Tu-2
    Tupolev Tu-2
    |-See also:-References:NotesBibliography* Bishop, Chris. The Encyclopedia of Weapons of WWII: The Comprehensive Guide to Over 1,500 Weapons Systems, Including Tanks, Small Arms, Warplanes, Artillery, Ships, and Submarines. New York: Sterling, 2002. ISBN 1-58663-762-2.* Ethell, Jeffrey L. Aircraft...

    .
  • SBB-1 — Archangelskii's last iteration of the SB, based on SB-MN and -RK, with even smaller wings (16.0 m (52 ft 5⅞ in) span) twin tail
    Twin tail
    A twin tail is a specific type of vertical stabilizer arrangement found on the empennage of some aircraft. Two vertical stabilizers — often smaller on their own than a single conventional tail would be — are mounted at the outside of the aircraft's horizontal stabilizer...

     and other changes. Alternative designation B. One prototype flown 1940 but no production.
  • Avia B-71 - SB 2M-100A licence built in Czechoslovakia.
  • PS-40 - cargo version for Aeroflot
    Aeroflot
    OJSC AeroflotRussian Airlines , commonly known as Aeroflot , is the flag carrier and largest airline of the Russian Federation, based on passengers carried per year...

    , powered by M-100A engines and with all military equiment removed. Capable of carrying cargo or six passengers. 100 supplied during 1938.
  • PS-41 - Conversion of SB 2M-103 as freighter for Aeroflot. PS-41bis fitted with underwing fuel tanks.
  • Pterodactyl - SB 2M-103 fitted with fixed tricycle landing gear. One converted 1940.
  • ANT-46 - two-seat heavy fighter, similar to ANT-401, but powered by two imported 597 kW (800 hp) Gnome-Rhône 14K engines and armed with two 100 mm recoilless rifle
    Recoilless rifle
    A recoilless rifle or recoilless gun is a lightweight weapon that fires a heavier projectile than would be practical to fire from a recoiling weapon of comparable size. Technically, only devices that use a rifled barrel are recoilless rifles. Smoothbore variants are recoilless guns...

    s in outer wings, four fixed machine guns in the nose, and one flexibly mounted machine gun in the observers cockpit. One prototype, with Air Force designation DI-8 first flown in August 1935, but abandoned after abandonment of Leonid Kurchevsky
    Leonid Kurchevsky
    Leonid Vasilyevich Kurchevsky was a Russian/Soviet weapons designer....

    's recoilless rifle projects and his subsequent arrest.
  • Tupolev ANT-41
    Tupolev ANT-41
    -References:* Duffy, Paul and Andrei Kandalov. Tupolev: The Man and His Aircraft. Shrewsbury, UK: Airlife, 1996. ISBN 1 85310 728 X.* Gordon, Yefim and Vladimir Rigmant. OKB Tupolev: A History of the Design Bureau and its Aircraft. Hinckley, UK: Midland Publishing, 2005. ISBN 1 85780 214 4.*...

     - unrelated Torpedo bomber
    Torpedo bomber
    A torpedo bomber is a bomber aircraft designed primarily to attack ships with aerial torpedoes which could also carry out conventional bombings. Torpedo bombers existed almost exclusively prior to and during World War II when they were an important element in many famous battles, notably the...

     with similar layout to SB but larger and more powerful. One built in 1936, abandoned after destroyed in crash due to severe flutter.

Operators

 Kingdom of Bulgaria
  • Bulgarian Air Force
    Bulgarian Air Force
    The Bulgarian Air Force is a branch of the Military of Bulgaria, the other two being the Bulgarian Navy and Bulgarian land forces. Its mission is to guard and protect the sovereignty of Bulgarian airspace, to provide aerial support and to assist the Land Forces in case of war. The Bulgarian Air...

     operated 32 Avia B-71 aircraft redesignated Avia-Katiusza Ě-8.

  • Chinese Nationalist Air Force received 62 SB-2M-100 bombers in the autumn 1937. The Soviet Union delivered more SB-2M-100 and SB-2M-105 bombers from August 1938-June 1941.

  • Czechoslovakian Air Force received 60 Russian-built SB with Hispano Suiza 12Ybrs engines in April and May 1938. Another 101 bombers and 60 reconnaissance aircraft were license-built Avia B-71 but only 101 were built.

  • Finnish Air Force
    Finnish Air Force
    The Finnish Air Force is one of the branches of the Finnish Defence Forces. Its peacetime tasks are airspace surveillance, identification flights, and production of readiness formations for wartime conditions...

     operated 24 SB bombers. The first eight aircraft (seven powered by M-103 engines, one by M-100 engines) were captured during the Winter War
    Winter War
    The Winter War was a military conflict between the Soviet Union and Finland. It began with a Soviet offensive on 30 November 1939 – three months after the start of World War II and the Soviet invasion of Poland – and ended on 13 March 1940 with the Moscow Peace Treaty...

    , another 16 aircraft were converted from German-captured material from 5 November 1941-27 August 1942. All aircraft were refitted with M-103 engines and were used as anti-submarine aircraft in the LeLv 6 squadron. Two aircraft were rebuilt and were used as trainers. The Finnish Air Force withdrew all SB aircraft in 1945, and all were scrapped in 1950.

 Germany
  • Luftwaffe
    Luftwaffe
    Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....

     operated captured aircraft, Czech-built Avia B-71 and Soviet SB.

  • Polish Air Force
    Polish Air Force
    The Polish Air Force is the military Air Force wing of the Polish Armed Forces. Until July 2004 it was officially known as Wojska Lotnicze i Obrony Powietrznej...

     operated few USB-2M-103 aircraft for training after World War II.

  Slovakia
  • Slovak Air Force
    Slovenské vzdušné zbrane
    The Slovak Air Force , between 1939 and 1945, was the air force of the short-lived World War II Slovak Republic. Its mission was to provide air support at fronts, and to protect Bratislava and metropolitan areas against enemy air strikes...

     operated one Avia B-71 aircraft until April 18, 1943, when čtk Anton Vanko and four other airmen defected with it to Turkey.

  • Soviet Air Force
    Soviet Air Force
    The Soviet Air Force, officially known in Russian as Военно-воздушные силы or Voenno-Vozdushnye Sily and often abbreviated VVS was the official designation of one of the air forces of the Soviet Union. The other was the Soviet Air Defence Forces...

  • Aeroflot
    Aeroflot
    OJSC AeroflotRussian Airlines , commonly known as Aeroflot , is the flag carrier and largest airline of the Russian Federation, based on passengers carried per year...

     received an unknown number of retired military SB-2M-100 aircraft in 1938 and after rebuild, used them under the designation PS-40. Another batch of retired SBbis 3 bombers was rebuilt in 1940 and used under the designation PS-41.

  • Republican Spanish Air Force received its first 31 SB-2M-100A bombers on 14 October 1936. The second batch of 31 aircraft was delivered in June-July 1937 and a final batch of 31 following in 1938. The Soviet Union delivered a total of 93 SBs to Spain.

  • Nationalist Spanish Air Force captured 19 SB-2M-100A bombers. All were overhauled and Soviet M-100 engines were replaced with French Hispano Suiza 12Ybrs. These aircraft were used operationally and later for training duties, and were retired in 1950. Spanish pilots called captured SB bombers Katiuska.

Recovery and Restoration

After Stalin's post-war cleanup in the 1950s, many ANT-40s that survived the Second World War were scrapped. In the late 1970s, however, Vozdushni Transport (A Soviet aviation newspaper) sent an expedition led by Evgeny Konoplev to survey an ANT-40 that was forced to land during a snow storm near the Yuzhne Muiski mountain range in the Baikal region. Konoplev considered what they found encouraging, with the aircraft being in fairly decent condition, in turn leading a team of VVS pilots to recover the airplane. It was returned to Moscow and restored by a group of volunteer Tupolev employees. The restored aircraft was unveiled in April 1982 at the Central Air Force Museum
Central Air Force Museum
The Central Air Force Museum in Monino at the site of Monino Airfield 40km east of Moscow, Russia, is one of the world's largest aviation museums, and the largest for Russian aircraft...

 at Monino Airfield
Monino Airfield
Monino Airfield is a former air base in Moscow Oblast, Russia located 36 km east of Moscow.It is used for the Central Air Force Museum. It had a military technical school with an operations ramp which during the 1990s had an Ilyushin Il-76 freighter jet and two bombers.This airfield appears to...

, the only known surviving ANT-40 of the almost 7,000 built.

Specifications (SB 2M-103)

See also

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