The
Tupolev ANT-40, also known by its service name
Tupolev SB (Russian:
Скоростной бомбардировщик –
Skorostnoi Bombardirovschik – "high speed bomber"), and development co-name
TsAGI-40, was a high speed twin-engined three-seat monoplane bomber, first flown in 1934.
The design was very advanced, but lacked refinement, much to the dismay of crews and maintenance personnel – and of Stalin, 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 aircraft produced in quantity in the Soviet Union and probably the most formidable bomber of the mid-1930s. Many versions saw extensive action in Spain, the Republic of China, Mongolia, Finland and at the beginning of the War against Germany in 1941. It was also used in various duties in civil variants, as trainers and in many secondary roles.
Successful in the Spanish Civil War because it outpaced most fighters, the aircraft was obsolete by 1941. By June 1941, 94% of bombers in the Red Army air force (VVS RKKA) were SBs.
Operational history
There were a number of foreign customers for the SB. 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 a 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 broke out on 17 July 1936. An initial batch of 31 SBs arrived in Cartagena aboard the Soviet Freighter
Komsomol in October 1936, flying their first mission, a bombing raid by four SBs against Tablada airfield, Seville on 28 October. The SBs were used to equip
Grupo 12 of the Spanish Republican Air Force, which at first was mainly manned by Soviet volunteers and under Soviet control.
The SB could outpace the Fiat CR.32 and Heinkel He 51 biplane
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, mistaking it for the Nationalist cruiser
Canarias, 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 109s to re-equip the German Condor Legion 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 12Ybrs engines to aid maintenance, they were still subject to spares shortages, and in April 1943 only three were airworthy. When Junkers Ju 88s
were received in December 1943, the remaining SBs were used for
occasional training flights until withdrawn and scrapped in 1948.
China
Soviet aviators at Hankou airfield.
In July 1937, the Second Sino-Japanese War 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,
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. On 23 February 1938, to celebrate Soviet Army Day,
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.
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 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 Hudsons and B-25 Mitchells. Limited numbers of SBs continued in non-combat use, including operations against opium plantations, before being used against the Communists when the Chinese Civil War 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 on the border between the Soviet Union and Manchuria 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
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 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 in the conflict that became known as the Winter War,
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
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.
Eastern Front
When Germany invaded the Soviet Union
in June 1941, re-equipment with more modern aircraft such as the Pe-2
had begun. Still, 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 started Operation
Barbarossa with co-ordinated strikes against 66 major Soviet airfields,
destroying a large proportion of Soviet air strength on the ground or
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, in the defense of Leningrad and Moscow, mainly at night by attacking German artillery. By December 1941 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, and continued in use in the Far East until
1945.
Finnish use
Tupolev SBs of the Finnish Air Force lined up.
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 for possible repair for use by the Finnish air force. By the time of the Continuation 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, 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.
These SBs employed the first air-dropped depth charges
used in combat. 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.
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"Just had luck ... / Nochmal Glück gehabt ... ! "
