Martin B-10 Explained

The Martin B-10 was the first all-metal monoplane bomber to be regularly used by the United States Army Air Corps, having entered service in June 1934.[1] It was also the first mass-produced bomber whose performance was superior to that of the Army's pursuit aircraft of the time.[2]

The B-10 served as the airframe for the B-12, B-13, B-14, A-15 and O-45 designations using Pratt & Whitney engines instead of Wright Cyclones.A total of 348 of all versions were built. The largest users were the US, with 166, and the Netherlands, with 121.

Design and development

The B-10 began a revolution in bomber design. Its all-metal monoplane airframe, along with its features of closed cockpits, rotating gun turrets (almost simultaneously with the 1933 British Boulton & Paul Overstrand biplane bomber's own enclosed nose-turret), retractable landing gear, internal bomb bay, and full engine cowlings, became the standard for bomber designs worldwide for decades.[2] It made all existing bombers completely obsolete. Martin received the 1932 Collier Trophy for designing the XB-10.[3]

The B-10 began as the Martin Model 123, a private venture by the Glenn L. Martin Company of Baltimore, Maryland. It had a crew of four: pilot, copilot, nose gunner and fuselage gunner. As in previous bombers, the four crew compartments were open, but it had a number of design innovations as well.[4] [5]

These innovations included a deep belly for an internal bomb bay and retractable main landing gear. Its 600hp Wright SR-1820-E Cyclone engines provided sufficient power. The Model 123 first flew on 16 February 1932 and was delivered for testing to the U.S. Army on 20 March as the XB-907. After testing it was sent back to Martin for redesigning and was rebuilt as the XB-10.[4] [5]

The XB-10 delivered to the Army had major differences from the original aircraft. Where the Model 123 had Townend rings, the XB-10 had full NACA cowlings to decrease drag.[6] It also sported a pair of 675hp Wright R-1820-19 engines, and an 8feet increase in the wingspan, along with an enclosed nose turret. When the XB-10 flew during trials in June, it recorded a speed of 197mph at 6000feet. This was an impressive performance for 1932.[2]

Following the success of the XB-10, a number of changes were made, including reduction to a three-man crew and addition of canopies for all crew positions. The Army ordered 48 of these on 17 January 1933. The first 14 aircraft were designated YB-10 and delivered to Wright Field, starting in November 1933, and used in the Army Air Corps Mail Operation. The production model of the XB-10, the YB-10, was very similar to its prototype.

Operational history

United States

In 1935, the Army ordered an additional 103 aircraft designated B-10B. These had only minor changes from the YB-10. Shipments began in July 1935. B-10Bs served with the 2d Bomb Group at Langley Field, the 9th Bomb Group at Mitchel Field, the 19th Bomb Group at March Field, the 6th Composite Group in the Panama Canal Zone, and the 4th Composite Group in the Philippines. In addition to conventional duties in the bomber role, some modified YB-10s and B-12As were operated for a time on large twin floats for coastal patrol.[7] [8]

In February 1936, the US Army Air Corps used 13 B-10Bs of the 49th Bomb Squadron to drop supplies to the residents of Virginia's Tangier Island and Maryland's Smith Island; with ships unable to reach the islands due to heavy ice in the Chesapeake Bay, the islanders faced starvation after a severe winter storm. The B-10B supply flights followed earlier supply flights to the islands by the Goodyear Blimp Enterprise on 2 February 1936 and by the squadron's Keystone B-6A bombers on 9 and 10 February 1936.[9] [10]

With its advanced performance, the Martin company fully expected that export orders for the B-10 would flood in. The U.S. Army owned the rights to the Model 139 design. Once the Army's orders had been filled in 1936, Martin received permission to export Model 139s, and delivered versions to several air forces. These included six Model 139Ws sold to Siam in April 1937, powered by Wright R-1820-G3 Cyclone engines, and 20 Model 139Ws sold to Turkey in September 1937, powered by R-1820-G2 engines.

China

ROCAF purchased the 139WC in 1936, When introduced, it was the fastest aircraft in China.

The 139WC was primarily used for night bombing and maritime reconnaissance.[11]

On 25 August 1937, as the air battles intensified in the early part of the Second Sino-Japanese War,[12] five Chinese Nationalist Air Force bombers of the 8th BG, 19th and 30th Squadrons consisting of three Heinkel He 111As and two Martin B-10s, flying from their base in Nanjing to Shanghai, successfully dropped their bombs on Japanese landing forces at Liuhe, Taicang, northwest of Shanghai. However, Japanese aircraft pursued the bombers and shot up two of the Heinkels, forcing them to crash land; two crew members were killed on the ground by Japanese aircraft strafing them.[13] [14]

As the National Revolutionary Army of China fought desperately to hold onto their remaining positions in the Battle of Shanghai, the Chinese Air Force launched a major strike with a motley mix of aircraft against Japanese positions in Shanghai on 14 October 1937, consisting of three B-10s, two Heinkel He 111As, five Douglas O-2MCs, five Northrop Gammas, and three Curtiss Hawk IIIs from Nanjing in the late afternoon; in the evening, one bomber was launched every hour from Nanjing to attack Japanese positions in Shanghai until 03:00 on 15 October.

On 19 May 1938, two B-10s of the 2nd BG, 14th Squadron, led by Capt. Hsu Huan-sheng and Lt. Teng Yen-bo, successfully flew the first air raid on mainland Japan.

During an unescorted nighttime raid over Japan, the B-10s dropped 2 million leaflets, "alerting the conscience of the Japanese people against atrocities committed by the Japanese invasion and occupation of China", over the cities of Nagasaki, Fukuoka, Kurume, Saga, and others, while reconnoitering airbases, ports, warships and factories.[15] [16] [17] [18] [19]

Dutch East Indies

In the mid-1930s, the Netherlands government adopted a doctrine for defense of the Netherlands East Indies, which relied on the use of land-based bombers against any attacking force, with orders for defensive fighters cancelled to pay for the bomber force. The Martin 139 was chosen in preference to the Dutch Fokker T.V, as its all metal construction was considered more robust than the steel tube and fabric Fokker, while the Martin bomber was also already in production and therefore would be available sooner.[20] Twelve Martin 139 WH-1s were ordered for the Royal Netherlands East Indies Army Air Force (ML-KNIL) in 1936, followed by 26 improved WH-2s in March 1937, sufficient bombers to equip a Group of three squadrons.[21] In December 1937, an order was placed for 39 Martin 139 WH-3s, followed by an order for 40 Martin 139 WH-3As in November 1938. Two more Martin 139 WH-3As were ordered in July 1939 to replace aircraft lost during delivery. The last of these attrition replacement aircraft was delivered in March 1940, including the last Martin B-10/139 built.[22] On the outbreak of war with Japan in December 1941, about 58 Martins (WH-3 and WH-3As) were operational with six squadrons, with about 20 more of the older variants in reserve.[23] B-10s of the ML-KNIL served in the defense of the Dutch East Indies.

During the start of Pacific War, Dutch Martin units were as follows:[24]

In efforts to reinforce the British defense of the Malay Peninsula, the Dutch East Indies sent some ML-KNIL squadrons. Included were 22 Martin 139s from VLG-III that were organized into three squadrons, which arrived at Singapore on 9 December 1941. Due to a lack of coordination, British AA mistook the Dutch Martins for enemy aircraft and engaged them as they neared Singapore. The Martins were then stationed at Sembawang.[25] In early January 1942, Dutch Martins along with British Blenheim bombers sortied over the west coast of Malaya to halt the Japanese advance.[26] On 8 January, nine Martin and four Australian Hudson attacked a suspected Japanese seaplane tender anchored offshore in South China Sea, but the results were inconclusive. In the next day, nine Martin "quite successfully" bombed several Japanese ships unloading cargo at Kuantan.[27] Two Martins were shot down by the Japanese near Penang on 1 January, while a further four Martins were lost while attacking Japanese forces on the Muar River on 19 January. On the same day, Dutch fighter squadrons were withdrawn to Sumatra, while the Martins were also withdrawn to Java three days later.[28]

Thailand

Six B-10s formed the medium bomber force of the Royal Thai Air Force at the start of the 1940–1941 Franco-Thai War. They flew several bombing missions during the war, with their first mission against Xieng Khuang, Laos and a nearby airfield on 15 December 1940,[29] with the last mission, against Sisophon in what is now Cambodia on 28 January at the very end of the Franco-Thai War.[30] Later on, B-10s had been assigned to the airfield in Phrae as a part of Phayap Army to invade Shan state.[31]

Turkey

After being delivered in September 1937, the Martin 139WTs were assigned to the 55th and 56th Tayyare Bölüğü (Aviation Squadrons) of the 9th Tayyare Taburu (Aviation Battalion).[32] During the Second World War, the aircraft were extensively deployed for surveillance over the Black Sea.[33] After being replaced by British Blenheims and Beauforts in 1944, the Martin 139WTs served as backup aircraft until 1946, when twelve of the sixteen remaining aircraft were still operational.

Legacy

At the time of its creation, the B-10B was so advanced that General Henry H. Arnold described it as the airpower wonder of its day. It was half again as fast as any biplane bomber, and faster than any contemporary fighter. The B-10 began a revolution in bomber design, making existing bombers completely obsolete.[6]

Rapid advances in bomber design in the late 1930s meant that the B-10 was eclipsed by the time the United States entered World War II. The Model 139s in combat in China and South East Asia suffered the same disadvantages as the other early war medium bombers, i.e. not enough armour and guns, while it could not outrun the latest fighters.

An abortive effort to modernize the design, the Martin Model 146, was entered into a USAAC long-distance bomber design competition in 1934–5. The bomber came in a strong second place and was bested by only the Boeing B-17 in range and endurance. However, it had a higher ceiling of, was only slower, and carried less in bombs than the Boeing, at over half the cost. Nonetheless, the design was seen as a dead end, and the third-place contender, the Douglas B-18, was selected instead.[34]

Variants

Martin Model 123

Private venture of Martin company, predecessor of the XB-10, served as prototype for the series, one built.[35]

XB-907
  • US Army designation for the Model 123 in evaluation,[35] with open cockpits and two Wright SR-1820-E, delivered April 1932.
    XB-907A
  • Modified XB-907 after Martin returned it to U.S. Army for further operational trials,[6] with larger wingspan and two Wright R-1820-19.
    XB-10
  • Designation of the prototype when purchased by the United States Army Air Corps, Modified XB-907A with enclosed cockpits and turret and single strut landing gear.[2] [36]

    Martin Model 139, 139A and 139B

    Army Air Corps versions, 165 built.

    YB-10
  • Model 139A, test and production version of the XB-10 with crew reduced to three members, and two R-1820-25, 14 built, some flown temporarily as float planes.[7]
    YB-10A
  • The YB-10A was different from a YB-10 only in its engines. It used Wright R-1820-31 turbo-supercharged radials, allowing it to attain speeds of . This made it the fastest aircraft of the B-10 series. Despite this advantage, only one was built, as a test aircraft.[7]
    B-10
  • According to one source, two additional aircraft ordered in 1936.[7]
    B-10B
  • Model 139, main production version with two R-1820-33 engines, 105 built, delivered August 1936.[7]
    B-10M
  • According to one source this was, these were B-10Bs converted as target tugs.[7] According to Martin's own archive, this was the designation of the YB-10 after testing, then used for airmail and Alaska missions, 13 of the 14 built were still in service in April 1940.
    RB-10MA
  • One former NEIAF Model 139WH-3A model impressed in July 1942 and flown from Australia to the United States.[7]
    YB-12
  • Model 139B. With 250USgal500USgal flotation chambers for safety on overwater flights, and two Pratt & Whitney R-1690-11 "Hornet" radial engines. These engines gave similar performance to those on the B-10B, seven built, five still in service in April 1940.[7]
    (Y)B-12A
  • The production version of the YB-12 with provision for a fuel tank in the bomb bay, giving the B-12A a combat range of, 25 built, 23 still in service in April 1940.[7]
    YB-13
  • Re-engined version of the YB-10 powered by two Pratt & Whitney R-1860-17 Hornet B radial engines. Ten were on order but cancelled before production started, not built.[7]
    XB-14
  • To test the new Pratt & Whitney YR-1830-9 "Twin Wasp" radial engines, one built which was converted back to YB-12 after testing.[7]
    A-15
  • Proposed attack variant of the YB-10 with two R-1820-25 engines, was never built. The contract fell to the A-14 Shrike.[37]
    YO-45
  • With two Wright R-1820-17, proposed high-speed observation role, one B-10 was beginning to be converted in 1934 and another in 1935 but both were stopped before being completed and were converted back into B-10s.

    Model 139W and 166

    The export versions, 100 built (182 including the Model 166, see below).

    Model 139WA
  • Martin demonstrator for Argentina, later sold to Argentine Navy.
    Model 139WAA
  • Export version for Argentine Army, 22 built, delivered April 1938.
    Model 139WAN
  • Export version for the Argentine Navy, 12 built, delivered November 1937.
    Model 139WC and WC-2
  • Export version for China, six and three built, delivered in February and August 1937.[1] [38]
    Model 139WH
  • Export version for the Netherlands, used in the Netherlands East Indies. Thirteen WH-1s, powered by 770hp Cyclone GR-1820-F53 engines delivered from December 1936, followed by 26 WH-2s, with 875hp GR-1820-G3 engines, delivered 1938.[39]
    Model 139WR
  • Single demonstrator to the Soviet Union.[7] [38]
    Model 139WSM and WSM-2
  • Export version for Siam, three and three built, delivered in March and April 1937.[7]
    Model 139WSP
  • Proposed license built version to be built by CASA of Spain, production blocked by U.S. State Department.
    Model 139WT
  • Export version for Turkey, 20 built, delivered September 1937.[1]
    Model 166Final version, a.k.a. 139WH-3 and 139WH-3A, 82 built.
  • Export version for the Netherlands, used in the Netherlands East Indies. Redesigned wings, nose and single 'glass house' canopy, bomb shackles between engines and fuselage, and better engines. The WH-3 had two R-1820-G5 (40 built, delivered September 1938), the WH-3A had two R-1820-G-105A (42 built, delivered March 1940). With the bomb shackles, the bomb load could be doubled for a shorter range. A total of 121 of all types were built for the Dutch.[7]

    Operators

    Thailand
    United States

    Surviving aircraft

    Sources

    Further reading

    External links

    Notes and References

    1. Jackson 2003, p. 246.
    2. Eden and Moeng 2002, p. 931.
    3. Collier Trophy Is Presented to Martin, 1 June 1933.
    4. https://books.google.com/books?id=aygDAAAAMBAJ&pg=PA51 "Flying Fish–Our Army's Newest Plane Hits Terrific Speeds (photo of Model 123, US Army designation XB-907, in flight)."
    5. http://aerofiles.com/_martin.html "M-list."
    6. Fitzsimons 1969, p. 1846.
    7. Eden and Moeng 2002, p. 932.
    8. Swanborough and Bowers 1964, p. 331.
    9. https://books.google.com/books?id=OsIBdVV_YOAC&pg=PA43&lpg=PA43 Bentley, Stewart W., Jr., PhD., The Touch of Greatness: Colonel William C. Bentley, Jr., USAAC/USAF; Aviation Pioneer
    10. Anonymous, "Bombing Planes to Bring Food to Ice Victims," Chicago Tribune, 2 February 1936.
    11. Web site: Cluett . Nathan . 2023-06-23 . Martin B-10 - A Leap in Military Aviation . 2024-06-17 . PlaneHistoria . en-US.
    12. Web site: Sun. Lianggang. Shanghai 1937 – Where World War II Began. 2020-11-20. SHANGHAI 1937: WHERE WORLD WAR II STARTED. en-US.
    13. Web site: Martyr Chen Xiong-ji. 2020-11-20. air.mnd.gov.tw. en.
    14. Web site: Martyr Yun Feng-zeng. 2020-11-20. air.mnd.gov.tw. en.
    15. Dunn, Richard L. "Illusive Target: Bombing Japan from China." warbirdforum.com, 2006. Retrieved: 16 May 2013.
    16. https://books.google.com/books?id=Re8pJnCXvWoC&pg=PA265 Li & Li 1998
    17. https://books.google.com/books?id=mpSkIrOCrQkC&pg=PA126 Xu 2001
    18. https://books.google.com/books?id=s2NKutuUlA8C&pg=PA320 Fenby 2009
    19. https://books.google.com/books?id=N6yy9mXwAEUC&pg=PA86 Underwood 1942
    20. Casius 1983, pp. 1–2.
    21. Casius 1983, p. 2.
    22. Casius 1983, p. 3
    23. Shores, Cull & Izawa 1992, pp. 59–60
    24. Oktorino 2019, pp. 42
    25. Oktorino 2019, pp. 82–83
    26. Oktorino 2019, pp. 84–85
    27. Oktorino 2019, pp. 93 & 96
    28. Oktorino 2019, pp. 99
    29. Young 1984, pp. 27–28
    30. Young 1984, p. 33
    31. Web site: https://www.finearts.go.th/chiangmailibrary/view/7088-%E0%B9%80%E0%B8%8A%E0%B8%B5%E0%B8%A2%E0%B8%87%E0%B9%83%E0%B8%AB%E0%B8%A1%E0%B9%88%E0%B8%81%E0%B8%B1%E0%B8%9A%E0%B8%A0%E0%B8%B1%E0%B8%A2%E0%B8%97%E0%B8%B2%E0%B8%87%E0%B8%AD%E0%B8%B2%E0%B8%81%E0%B8%B2%E0%B8%A8. th:เชียงใหม่กับภัยทางอากาศ. th. National Library of Chiang Mai. 2023-06-23.
    32. Web site: MARTIN 139 WT B10 .. 1923 - 1950 Period TUAF 1923 -1950 dönemi Turk HvKK UCAKLARI. 2023-01-07. www.tayyareci.com. 7 January 2023. https://web.archive.org/web/20230107110746/http://www.tayyareci.com/digerucaklar/turkiye/1923ve50/martin139wt.asp. dead.
    33. Web site: Oryx. From Martin 139 To Kızılelma: 85 Years Of Turkish Bombers. 2023-01-07. Oryx.
    34. David D Gravermoen B-10 - The Martin Bomber
    35. Fitzsimons 1967/1969, p. 1845.
    36. http://www.10af.afrc.af.mil/shared/media/photodb/photos/060511-F-1234S-003.jpg "Photo of XB-10."
    37. Swanborough and Bowers 1964, p. 332.
    38. Baugher, Joe. "Martin B-10". American Military Aircraft, 11 July 1999. Retrieved: 13 June 2010.
    39. Casius 1983, pp. 2–3, 6.
    40. Web site: Catálogo Ilustrado de Aeronaves de la Fuerza Aérea Argentina. Ay. Carlos. es. 2013-08-15. Gaceta Aeronautica. 2014-05-31.
    41. http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=3366 "Donation of the Martin B-10."
    42. Andersson 2008, p. 275
    43. Web site: Photos as well as paintings of ROC. 2013-06-13. 2013-10-20. https://web.archive.org/web/20131020064937/http://cwlam2000.0catch.com/caf30.htm. dead.
    44. Shores, Cull and Izawa 1992, pp. 38, 56.
    45. Young 1984, p. 23.
    46. Casius 1983, p. 20.
    47. http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=3366 "USAF Fact Sheet Martin B-10."
    48. Coordinates 1.8774°N 116.8734°W
    49. Web site: Menguak Misteri Gunung Pesawat: Nama Diambil dari Pesawat yang Jatuh. berau.prokal.co. 2018-08-17. 2022-09-26. ID.
    50. Web site: Pesawat di Gunung Itu Diduga Martin B-10. berau.prokal.co. 2018-08-17. 2022-09-26. ID.
    51. Web site: Misteri Gunung Pesawat di Kabupaten Berau. tintakaltim.com. 2019-03-26. 2022-09-26. ID.
    52. Web site: Accident Martin 166 WH-3 M-574, 05 Jan 1941. aviation-safety.net. 2022-09-26.
    53. http://www.militaireluchtvaartmuseum.nl/ "Martin B-10" (in Dutch).

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