| NA-40 | |
|---|---|
.jpg) | |
| General information | |
| Type | Attack bomber |
| National origin | United States |
| Manufacturer | North American Aviation |
| Primary user | United States Army Air Corps |
| Number built | 1 |
| History | |
| First flight | January 1939 |
| Developed from | North American XB-21 |
| Developed into | North American B-25 Mitchell |
TheNorth American NA-40 was an American prototypebomber aircraft developed byNorth American Aviation in the late 1930s for evaluation by theUnited States Army Air Corps. Although unsuccessful, it led directly to theNorth American B-25 Mitchell medium bomber.
The Air Corps issued a circular (number 38-385) in March 1938 describing the performance they required from the next bombers — a payload of 1,200 lb (540 kg) with a range of 1,200 mi (1,900 km) at more than 200 mph (320 km/h).[1] Several American aircraft companies responded with submissions: Bell Model 9 with two engines,Boeing-Stearman Model X-100 with Pratt & Whitney R-2180 radials,Douglas Model 7B with Pratt & Whitney R-1830 Twin Wasp radials,Martin Model 167F[1] and North American submitted their NA-40 design. The NA-40 had benefited from theNorth American XB-21 (NA-39) of 1936, which was the company's partly successful design for an earlier medium bomber that had been initially accepted and ordered, but then cancelled. However, the company's experience from the XB-21 contributed to the design and development of the NA-40. The single NA-40 built flew first at the end of January 1939. It went through several modifications to correct problems. These improvements included fitting 1,600 hp (1,193 kW)Wright R-2600 "Twin Cyclone"radial engines, in March 1939, which solved the lack of power.[1]
In March 1939, North American delivered the substantially redesigned and improved NA-40 (as NA-40B) to theUnited States Army Air Corps for evaluation.[1] It was in competition with other manufacturers' designs produced - the Bell had not been built - Douglas 7B, Stearman XA-21, and the Martin Model 167F[2] but failed to win orders. The aircraft was originally intended to be an attack bomber for export to the United Kingdom and France, both of which had a pressing requirement for such aircraft in the early stages of World War II.
Despite the loss of the 7B in an accident injuring a French observer in January, the French had ordered the 7B and a revised version (as the DB-7). Unfortunately, the NA-40B was destroyed in acrash on 11 April 1939 while undergoing testing. Although the crash was not considered due to a fault with the aircraft design, the U.S. Army ordered the DB-7 as theA-20 Havoc.[3][4]
The Air Corps issued a specification for a medium bomber in March 1939 that was capable of carrying a payload of 2,400 lb (1,100 kg) over 1,200 miles (1,900 km) at 300 mph (480 km/h)[5] NAA used the NA-40B design to develop the NA-62, which competed for the medium bomber contract. No YB-25 was available for prototype service tests. In September 1939, the Air Corps ordered the NA-62 into production as the B-25, along with the other new Air Corps medium bomber, theMartin B-26 Marauder "off the drawing board".
Data from Baugher[1]
General characteristics
Performance
Armament
Related development
Aircraft of comparable role, configuration, and era
Related lists
