The North American B-25 Mitchell is an American twin-engine, medium bomber manufactured by North American Aviation (NAA). It was named in honor of Major General William "Billy" Mitchell, a pioneer of U.S. military aviation. Used by many Allied air forces, the B-25 served in every theater of World War II and after the war ended many remained in service, operating across four decades. Produced in numerous variants, nearly 10,000 Mitchells rolled from NAA factories. These included a few limited models, such as the United States Marine Corps' PBJ-1 patrol bomber and the United States Army Air Forces' F-10 reconnaissance aircraft and AT-24 trainers.

Design and development

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). Those performance specifications led NAA to submit their NA-40 design. The NA-40 had benefited from the North 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 Wright R-2600 "Double Cyclone" radial engines, in March 1939 which solved the lack of power.

The United States Military Aircraft Designation System was first designed in 1919 when the US Army's Aeronautical Division became the United States Army Air Service. Before this aircraft were put into service under their manufacturers' designations.

History

United States Army Air Service 1919 to 1924

During this period Type Designations used by the United States Army Air Service were allotted, using two or three letters, which were an abbreviation of the aircraft's purpose. Examples include GA for Ground Attack aircraft; NO for Night Observation aircraft and NBS for Night Bombardment, Short Distance aircraft.

Army aviation 1924 to 1962

From 1924 to 1947 the Air Service, United States Army Air Corps, United States Army Air Forces and United States Air Force used a designation system based on mission category, with each model in a category numbered sequentially. In 1947, the designation system was extensively overhauled, with several categories being dispensed with, and others renamed For instance, the Lockheed P-80 Shooting Star (Pursuit) was redesignated as F-80 (Fighter), while the A-26 medium bomber/attack aircraft was redesignated as the B-26, reusing the designation, the Martin B-26 having retired in the meantime.

B25, B-25 or B.25 may refer to: