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Dutch Modelling and Aviation

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In Memoriam

Klaas Willem Jonker
(Wilko)
† April 30, 2018

On Monday 30 April 2018, Wilko Jonker died after a long illness at the age of 58. He leaves behind a wife and two children. The Dutch military aviation and plastic modeling were his hobby and on this website he shared all the knowledge he has collected over the years. His hobby has been able to distract him from the persistent disease in his body until the last week of his life. The contacts with other hobbyists were a major support for him.

This website will be maintained by different people for as long as possible, so that other enthusiasts can continue to benefit from extensive content.

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Sunday, 25 August 2019 05:31

(Glenn-)Martin B.10 (139/166)

History

Like the MB during the 1920s and early thirties of the twentieth century the Martin B-10 series set standard for land bombers. The design was the first successful military application of the new airframe technology and had a streamlined monocoque fuselage, propellers with variable pitch adjustment, thick metal wings with lift enhancing flaps, integral fuel tanks and a retractable landing gear.

The B-10 was designed in response to an Air Corps bomber specification from late 1929. Besides Martin also Fokker, Keystone, Douglas, Ford and Boeing, presented a design or prototype.

The first Martin's proposal for a conventional biplane was rejected by the USAAC Equipment Division with a range of suggestions for improvement. In February 1932 Martin built for his own account, a new model of the 123 with two Wright R-1820 Cyclone engines. It had a speed of 317 km/h (197 mph), which was faster than competing aircraft. With the designation XB-907, the prototype was tested on Wright Field.

Several problems occurred, such as vibrations from the engines, instability during flight and furthermore the landing speed was too high; this turned out to be 146 km/hr (91 mph). So it was sent back to the Martin factory with a list of suggestions for improvement.

Partly due to the impact of the stock market crash of 1929 the design had now become vital for the survival of the Martin factory. Martin went to work on the results of the tests to improves the Martin 123.

The Martin 123 received extended wings, integrated with the hull and more powerful Cyclone engines mounted in new streamlined NACA caps.

The landing gear was changed and a new nose turret was developed.

 

In October 1932, the XB-907A was ready. The device was not only faster than the competing Boeing XB-9 and Douglas XB-7, but was also just as fast as the latest fighter aircraft of the USAAC from that time.

In January 1933 an order for 48 aircraft was scooped.

The XB-907A, was now referred to as XB-10 and 13 similar YB-10's had to be delivered plus one YB-10A for testing Wright engines with turbo compression had to be delivered.

Seven YB-12s were to be built for testing with Pratt & Whitney R-1690 Hornet engines, followed by 25 ordinary B-12A with the same engines, but equipped with extra fuel tanks and floating chambers and finally an experimental XB-14 with new Pratt & Whitney R-1830 Twin Wasps.

The YB-10 and YB-12 were delivered in early 1934 and were soon deployed for an unusual mission. All airmail contracts were cancelled due to corruption, and airmail now had to be taken care of by the USAAC.

The large, fast aircraft proved to be a godsend because of their reliability and security.

After these successes, Martin was actually expecting more large orders. Despite discussions Martin received contracts for 103 aircraft, in the final B-10B version with Wright R-1820/33 engines, spread over fiscal years 1934 and 1935.

The B-10's did service in every bombardment group of the Air Corps. In 1935 some were used for tests of Norden precision bomb sights.

The success stimulated the development of larger, long-range bombers which would replace the B-10, especially the Boeing B-17 Flying Fortress.

Already in 1936the USAAC lost interest in B-10 bomber. A few were tested as attack and observation plane, referred to as A-15 and D-45.

  Despite a number of disputes with Martin about the design and occurring construction defects in the B-10 series, in the spring of 1940, yet 119 of the 151 aircraft were still in service. Most were used as target tugs, and for training as a B-10M and B-12AM, though seventeen aircraft were still in operational service in the Philippines.

In 1936, the Martin 139 was released for export and 189 aircraft were eventually sold abroad.

The Soviets were in the summer of 1936, the first with the purchase of a single copy and blueprints, soon followed by the Netherlands East Indies, China, Siam, Argentina and Turkey with various orders.

The Dutch were the best customers with the purchase of a total of 120 aircraft in four different versions for the defence of the Dutch East Indies.

Foreign orders for Model 139 Martin kept the factory busy until 1939. One of the Argentine Martins is the only survivor of the type and was completely restored in the pre-war Air Corps colours and can be seen in the Air Force Museum at Wright-Patterson Air Force Base.

 

Technical information Glenn Martin WH-1
Dimensions:
Length: 13,6 m Wing span: 21,5 m
Height: 4,7 m Wing area: 63 m2
Weights:
Empty weight: 4391 kg Max. start weight: 6680 kg
Performance:
Cruising speed: 310 km/hr Max. speed: 343 km/hr
Climbing speed: 420 m/min    
Service Ceiling: 7380 m Range: 1996 km
Miscellaneous:
Engine type: Two Wright Cyclone R-1820-F53 rated 750 hp
Crew: Three men
Armament: Three 7.62 mm machine guns; 1000 kg bombs

 

Technical information Glenn Martin WH-2
Dimensions:
Length: 13,6 m Wing span: 51,5 m
Height: 4,7 m Wing area: 63 m2
Weights:
Empty weight: 4391 kg Max. start weight: 6680 kg
Performance:
Cruising speed: 310 km/hr Max. speed: 343 km/hr
Climbing speed: - m/min    
Service Ceiling: 7380 m Range: 1996 km
Miscellaneous:
Engine type: Two Wright Cyclone R-1820-G3 rated 840 hp
Crew: Three men
Armament: Three 7.62 mm machine gun; 1000 kg bombs

 

Technical information Glenn Martin WH-3 / WH-3A
Dimensions:
Length: 13,6 m Wing span: 51,5 m
Height: 4,7 m Wing area: 63 m2
Weights:
Weight (empty) - kg Weight (maximum) - kg
Performance:
Cruising speed: 310 km/hr Max. speed:  > 343 km/hr
Climbing speed: - m/min    
Service Ceiling: 7380 m Range: 1996 km
Miscellaneous:
Engine type: Two Wright Cyclone R-1820G-102 rated 900 hp each
Crew: Three men
Armament: Three 7.62 mm machine gun; 1000 kg bombs