"B-25" redirects here. For the British Second World War-era fighter plane, see Blackburn Roc
The North American B-25 Mitchell was an American twin-engined medium bomber manufactured by North American Aviation. It was used by many Allied air forces, in every theater of World War II, as well as many other air forces after the war ended, and saw service across four decades.
The B-25 was named in honor of General Billy Mitchell, a pioneer of U.S. military aviation. By the end of its production, nearly 10,000 B-25s in numerous models had been built. These included a few limited variations, such as the United States Navy's and Marine Corps' PBJ-1 patrol bomber and the United States Army Air Forces' F-10 photo reconnaissance aircraft.
Design and development
Flight Performance School included work in evaluating the performance of this B-25 Mitchell medium bomber
The B-25 was a descendant of the earlier XB-21 (North American-39) project of the mid-1930s. Experience gained in developing that aircraft was eventually used by North American in designing the B-25 (called the NA-40 by the company). One NA-40 was built, with several modifications later being done to test a number of potential improvements. These improvements included Wright R-2600 radial engines, which would become standard on the later B-25.
In 1939, the modified and improved NA-40B was submitted to the United States Army Air Corps for evaluation. This 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. However, those countries changed their minds, opting instead for the also-new Douglas DB-7 (later to be used by the U.S. as the A-20 Havoc). Despite this loss of sales, the NA-40B re-entered the spotlight when the Army Air Corps evaluated it for use as a medium bomber. Unfortunately, the NA-40B was destroyed in a crash on 11 April 1939. Nonetheless, the type was ordered into production, along with the Army's other new medium bomber, the Martin B-26 Marauder.
North American B-25 Mitchell production in Kansas City in 1942
An improvement of the NA-40B, dubbed the NA-62, was the basis for the first actual B-25. Due to the pressing need for medium bombers by the Army, no experimental or service-test versions were built. Any necessary modifications were made during production runs, or to existing aircraft at field modification centers around the world.
A significant change in the early days of B-25 production was a redesign of the wing. In the first nine aircraft, a constant-dihedral wing was used, in which the wing had a consistent, straight, slight upward angle from the fuselage to the wing tip. This design caused stability problems, and as a result, the dihedral angle was nullified on the outboard wing sections, giving the B-25 its slightly gull wing configuration. Less noticeable changes during this period included an increase in the size of the tail fins and a decrease in their inward cant.
A total of 6,608 B-25s were built at North American's Fairfax Airport plant in Kansas City, Kansas.
A descendant of the B-25 was the North American XB-28, meant to be a high-altitude version of the B-25. Despite this premise, the actual aircraft bore little resemblance to the Mitchell and in some respects more closely resembled the Martin B-26 Marauder.
Lt. Peddy and crew, showing how many people were required to keep a B-25 flying
The majority of B-25s in American service were used in the Pacific. It fought on Papua New Guinea, in Burma and in the island hopping campaign in the central Pacific. It was in the Pacific that the aircraft’s potential as a ground attack aircraft was discovered and developed. The jungle environment reduced the usefulness of standard-level bombing, and made low-level attack the best tactic. The ever-increasing amount of forward firing guns was a response to this operational environment, making the B-25 a formidable strafing aircraft.
In Burma, the B-25 was often used to attack Japanese communication links, especially bridges in central Burma. It also helped supply the besieged troops at Imphal in 1944.
In the Pacific, the B-25 proved itself to be a very capable anti-shipping weapon, sinking many ships. Later in the war, the distances between islands limited the usefulness of the B-25, although it was used against Guam and Tinian. It was also used against Japanese-occupied islands that had been bypassed by the main campaign, as happened in the Marshall Islands.
Middle East and Italy
The first B-25s arrived in Egypt just in time to take part in the Battle of El Alamein. From there the aircraft took part in the rest of the campaign in North Africa, the invasion of Sicily and the advance up Italy. In Italy the B-25 was used in the ground attack role, concentrating on attacks against road and rail links in Italy, Austria and the Balkans. The B-25 had a longer range than the Douglas A-20 Havoc and Douglas A-26 Invaders, allowing it to reach further into occupied Europe. The five bombardment groups that used the B-25 in the desert and Italy were the only U.S. units to use the B-25 in Europe.
The U.S. Eighth Air Force, based in Britain, concentrated on long-range raids over Germany and occupied Europe. Although it did have a small number units equipped with twin-engined aircraft, the B-25 was not amongst them. However, the RAF received nearly 900 Mitchells, using them to replace Douglas Bostons, Lockheed Venturas and Vickers Wellington bombers. The Mitchell entered active RAF service on 22 January 1943. At first it was used to bomb strategic targets in occupied Europe. After the D-Day invasion the RAF used its Mitchells to support the armies in Europe, moving several squadrons to forward airbases in France and Belgium.