Martin B-10

 

The B-10 waged a revolution in bomber design with its all-metal monoplane airframe, enclosed cockpits, rotating gun turrets, retractable landing gear, internal bomb bay and full engine cowlings. With all those features, the bomber marked the standard for the designs to come in the following decades, making the existing designs obsolete and Martin receiving the 1932 Collier Trophy for designing the XB-10.

It began initially as a private venture with the Martin Type 123, by Glenn L. Martin Company in Baltimore, Maryland. It was manned by a crew of four, pilot, co-pilot, nose gunner and fuselage gunner. At first, all four crew compartments were open, but it had a number of design innovations as well.

Innovations included a deep belly for an internal bomb bay and a retractable landing gear. The Type 123 was powered by two 600 hp Wright SR-1820-E Cyclone radial engines and flew for the first time on 16th February 1932. It was delivered to the US Army on 20th March as the XB-907 for testing. After evaluation by the US Army, it was sent back to Martin for redesign and improvement and it was rebuilt as the XB-10.

The XB-10 was later delivered to the US Army and it differed in many ways from the original aircraft. It had full NACA cowlings to decrease drag, while the XB-10 had Townend rings. It also was powered by two 675 hp Wright R-1820-19 engines and had a larger wingspan, together with an enclosed nose turret. When further trials were performed on the XB-10 in June 1932, it achieved a speed of 197 mph (317 km/h) at 6.000 ft (1.830 m) high, quite an impressive performance for the time. 

After the success of the XB-10, some changes were made to the design. The number of crew members was reduced to three and canopies for all of them were added. The US Army ordered an initial batch of 48 of these on 17th January 1933. The first 14 of them were labelled as YB-10 and were delivered to Wright Field, Ohio, from November 1933 onwards and used in the Army Air Corps Mail Operation.

Later, in 1935, the Army ordered an additional 103 aircraft, named as the Martin B-10B, which differed only in minor details from the YB-10. Deliveries began in July 1935 and they served with the 2nd Bomb Group at Langley Field, Virginia, the 9th Bomb Group at Mitchel Field, New York, the 19th Bomb Group at March Field, California, the 6th Composite Group in the Panama Canal Zone and the 4th Composite Group in the Philippines. Some modified YB-10s and B-12 (the remaining aircraft of the original order, which were powered by two Pratt & Whitney R-1690-11 Hornet radial engines) were operated with twin floats for coastal patrol duties.

In February 1936 thirteen B-10Bs belonging to the 49th Bomb Squadron dropped supplies to the residents of Tangier Island, in Virginia and Smith Island, in Maryland as ships couldn't reach due to heavy ice in the Chesapeake Bay and the inhabitants faced starvation after a sever winter storm. 

Although at the time of its creation it was a very advanced design (General Henry H. Arnold referred the bomber as the airpower wonder of its day), rapid advances in bomber design during later 1930s meant that the bomber was completely obsolete by the time the World War 2 began. A modernisation effort was made with the Martin 146, but it was superseeded by the Boeing B-17 and the Douglas B-18. 

Ironically, although by the time the USA entered the war the B-10 was retired from active service long ago, an export model used by the Dutch East Indies escaped to Australia on 7th March 1942 and was taken on strength by the USAAF to serve as an utility aircraft. That was the only Type 139WH-3/Type 166 to serve with the United States Army Air Forces.

Sources:

1. https://en.wikipedia.org/wiki/Martin_B-10

2. http://www.joebaugher.com/usaf_bombers/b10.html

Martin 139 in Dutch hands

 

The Martin Type 139 was an all-metal bomber monoplane, whose exportations were cleared in 1936. It was exported to many countries, most of them covered in previous posts, except for one, the Dutch East Indies.

The largest customer for the Martin Type 139 was the Dutch colony. They ordered twelve Type 139WH-1 (where the letter 'H' stands for Holland - the export version destined to serve in the Dutch East Indies) powered by two Wright R-1820-F53 Cyclone engines which delivered 750 hp of power each which were delivered between September 1936 and February 1937. This order was followed by additional 26 Type 139WH-2, a refined version, this time powered by R-1820-G3 engines which delivered up to 850 hp of power. This second batch was delivered between November 1937 and March 1938. The final export version, the Type 139WH-3, AKA Type 166 was powered by the R-1820 G-102 radial engines, capable of delivering up to 900 hp of power. This version featured also a redesigned fuselage with a long unbroken canopy "greenhouse" that ran all the way from the pilot's cockpit until the rear gunner's position. A total of 78 of the Type 166 were manufactured at Martin's factory in Baltimore between August 1936 and March 1938 before the production line was shut down. All of them had been delivered in the Dutch East Indies by 5th May 1939.

When Japan invaded the Dutch East Indies in December 1941, a total of six squadrons of Type 139 were present in the Dutch East Indies. They were flown in tactical bombing missions in a futile attempt to stop the Japanese advance during early 1942. By this time, the 139 was considerably obsolete with a speed, armour and weaponry completely inadequate to defend against the superior Japanese Mitsubishi A6M Zero, which the Type 139 couldn't stand against. Most of the Dutch 139 or 166 were either destroyed in aerial combat or on the ground. 

Sources:

1. http://www.joebaugher.com/usaf_bombers/b10.html

2. https://en.wikipedia.org/wiki/Martin_B-10

3. https://www.valka.cz/Martin-139W-t159440

4. https://www.valka.cz/Martin-166-t159445

Martin Type 139 - Various Foreign Users

 

The Martin Type 139 was an all-metal monoplane bomber that was used by the United States Army Air Corps and by many other countries:

• China: The National Revolutionary Army, (Kuomingtan's Armed Forces) ordered six 139s which Martin called them 'Type 139WC' (the letter 'C' standing for 'China'). This version was powered by two Wright R-1820 Cyclone engines which could deliver up to 850 hp of power each. 
  They arrived in China in February 1937 and were used in August against the Japanese in the Battle of Shanghai, where the Chinese Nationalist Air Force (CNAF) launched a major strike with a formation of various types of aircraft. One of such attacks took place on 14th October 1937 when three 139WC, two Heinkel He.111A, five Douglas O-2MCs, five Northrop Gammas and three Curtiss Hawk IIIs, based in Nanjing, bombed Japanese positions.
  Later, on 19th May 1938, the Type 139WC has the honour of being the first aircraft to conduct a raid into Japanese mainland. On that day, two 139WC belonging to the 2nd Bomber Group, 14th Squadron, commanded by Cpt. Hsu Huan-Sheng and Lt. Teng Yen-bo successfully flew a nighttime raid over Japan. However, instead of dropping bombs, they dropped propaganda leaflets over the cities of Nagasaki, Fukuoka, Kurume, Saga and some others, while making reconnaissance duties over ports, airports, warships and factories. 
  Most of the 139WC were destroyed during the course of the war.
• Japan: After the fall of the Dutch East Indies, three Type 139WH (the export version made for the Dutch colony) and Type 166 were captured intact by the Nippons and shipped to Haneda, Tokyo to be evaluated by the Testing Division of the Army Aircraft Authority. Their ultimate fate is unknown, but they were most likely destroyed during an air raid.
• Philippines: Apparently, some few B-10B (regular production variant) were leased to the Philippine Army Air Corps (PAAC) by the 4th Composite Group. They were most likely, destroyed during the Japanese invasion of the Philippines. As we couldn't find graphical evidence of a B-10B serving with the PAAC, the drawing should be considered as speculative.
• Thailand: Six Type 139WS (the 'S' standing for 'Siam') were sold to Thailand in April 1937. They saw action against the French in the Franco-Thai War in late 1940 and January 1941 and later they were used to support Japanese troops in their advance towards Burma in early 1942. They were complemented by an amount of ex-Dutch airplanes given by the Japanese later that same year. They were kept in active service until 1949.
• Turkey: When fascist Italy sought to expand their empire in the Mediterranean, the Turkish Government, decided to equip their air force with a long-range bomber. Therefore Cpt. Enver Akoglu was sent in a mission to the United States to purchase 20 Type 139WT ('T' standing for 'Turkey'). This variant was powered with uprated engines which could, theoretically, deliver up to 1.000 hp of power instead of the regular 750 hp. They arrived to Turkey in September 1937 and were assigned to 55 and 56th Tayyare Bölügü (Flying detachment, a squadron-sized unit) based at the city of Çorlu, in the Marmara region. Those were part of the higher 9th Tayyare Taburu unit. During 1941 and 1942 they were employed extensively in reconnaissance patrols over the Black Sea. When the type was showing its obsolescence, they were reassigned to other secondary and transport units. They were in active until 1946 with four of them crashing in 1945.

Sources:

1. en.wikipedia.org/wiki/Martin_B-10

2. http://www.joebaugher.com/usaf_bombers/b10.html

3. http://www.tayyareci.com/digerucaklar/turkiye/1923ve50/martin139wt.asp

Martin 139, South American and European Users

 

The Martin 139 (known in service with the United States Army Air Corps - USAAC) as B-10, was an American all-metal bomber, one of the first mass-produced in the 1930s that saw service with various countries. On this post we're covering the next ones:

• Argentina: Both Argentine Comando de Aviación del Ejército (Army Aviation Command) and Armada Argentina (Argentine Navy) used the Type 139. 
  In the mid-1930 the Army Aviation Command sought to modernise their bomber fleet and, in February 1937, after having studied other choices, they signed a contract with Martin for a total of 22 machines, which were designated by the company as Martin Type 139WAA (with the demonstrator being denominated just as Type 139WA). The bombers were assigned to the Regimiento de Aviación Nº1 (No.1 Aviation Regiment) at El Palomar Air Base, close to the capital, Buenos Aires and Regimiento 1 de Bombardeo (Bombing Regiment 1) of Villa Reynolds in the province of San Luis. They served until 1954, however, by that year the last three ones were being used as target tows. They were replaced by the native IAe-24 Calquin.
  The Argentine Navy acquired also a total of 12 new aircraft, plus a demonstrator, designated by the company as Type 139WAN. The contract was signed on 24th December 1936 and they were delivered in November 1937. They were assigned to two newly-formed bomber squadrons, one based at Punta Indio Naval Air Base, close to Buenos Aires and other one based at Comandante Espora Naval Air Base, close to Buenos Aires too. 
  This type was chosen by the Navy as the fuselage featured watertight compartments that could help with floatability in case of an emergency landing on sea and the type could also be fitted with EDO-made floaters. They also were the first airplane to feature a retractable landing gear to operate with the Argentine Navy. They all served until 1949.
• USSR: One aircraft, denominated by Martin as Martin Type 139WR, powered by two Wright R-1820-F53 Cyclone engines and Hamilton screws was bought by the Soviet Union for evaluation purposes. It seems that the performance of this machine wasn't satisfactory as no further machines were ordered by the Soviets and nothing is known about the fate of the aircraft. As there doesn't seem to be any graphical evidence of the type serving in Soviet colours, the drawing should be considered as speculative.
• Republic of Spain: The Spanish Republican Government had closed a deal for several Martin 139WSP (denomination given by the company), just before the outbreak of the Spanish Civil War. This deal also included the licensed production of the type by CASA, however, it was eventually blocked by the US State Department and the type was never delivered. When the Soviet Tupolev SB Katyusha appeared over the Spanish skies, many sources initially misidentified it as a "Martin Bomber"(which shouldn't come as a surprise as the Soviet aircraft types were kept under secrecy back in the 1930s).
  The presence of the 139WSP in the Spanish Civil War is even quoted by many authors and there are even some manipulated photographs, made with obvious propaganda purposes. We decided to draw a fictional version of the type serving with the Republican side.

Sources:

1. https://en.wikipedia.org/wiki/Martin_B-10

2. http://www.amilarg.com.ar/martin-139.html (translated)

3. https://web.archive.org/web/20200920135216/http://bioold.science.ku.dk/drnash/model/Spain/didnt.html

4. https://www.globalsecurity.org/military/systems/aircraft/b-10-foreign.htm