The Martin B-26 Marauder is an American twin-engine medium bomber that saw extensive service during World War II.
The B-26 was built at two locations: Baltimore, Maryland, and Omaha, Nebraska, USA.
First used in the Pacific Theatre of World War II in early 1942, it was also used in the Mediterranean Theatre and in Western Europe.
After entering service with the United States Army aviation units, the aircraft quickly received the reputation of a “widowmaker” due to the early models’ high accident rate during take-offs and landings.
This was because the Marauder had to be flown at precise airspeeds, particularly on final runway approach or when one engine was out.
The unusually high 150 mph (241 km/h) speed on short final runway approach was intimidating to many pilots who were used to much slower approach speeds, and when they slowed to speeds below those stipulated in the manual the aircraft would often stall and crash.
The B-26 became a safer aircraft once crews were re-trained, and after aerodynamics modifications (an increase of wingspan and wing angle-of-incidence to give better take-off performance, and a larger vertical stabilizer and rudder).
The Marauder ended World War II with the lowest loss rate of any U.S. Army Air Forces bomber.
A total of 5,288 were produced between February 1941 and March 1945; 522 of these were flown by the Royal Air Force and the South African Air Force.
By the time the United States Air Force was created as an independent military service separate from the United States Army in 1947, all Martin B-26s had been retired from U.S. service.
After the Marauder was retired the unrelated Douglas A-26 Invader then assumed the “B-26” designation which led to confusion between the two aircraft.
In March 1939, the United States Army Air Corps issued Circular Proposal 39-640, a specification for a twin-engined medium bomber with a maximum speed of 350 mph (560 km/h), a range of 3,000 mi (4,800 km) and a bomb load of 2,000 lb (910 kg).
On 5 July 1939, the Glenn L. Martin Company submitted its design, produced by a team led by Peyton M. Magruder, to meet the requirement, the Martin Model 179.
Martin’s design was evaluated as superior to the other proposals and was awarded a contract for 201 aircraft, to be designated B-26.
The B-26 went from paper concept to an operational bomber in approximately two years.
Additional orders for a further 930 B-26s followed in September 1940, still prior to the first flight of the type.
The B-26 was a shoulder-winged monoplane of all-metal construction, fitted with a tricycle landing gear.
It had a streamlined, circular section fuselage housing the crew, consisting of a bombardier in the nose, armed with a .30 in (7.62 mm) machine gun, a pilot and co-pilot sitting side by side, with positions for the radio operator and navigator behind the pilots.
A gunner manned a dorsal turret armed with two .50 in (12.7 mm) machine guns (the first powered dorsal turret to be fitted to a U.S. bomber), and an additional .30 in (7.62 mm) machine gun was fitted in the tail.
Two bomb bays were fitted mid-fuselage, capable of carrying 5,800 lb (2,600 kg) of bombs, although in practice such a bomb load reduced range too much, and the aft bomb bay was usually fitted with additional fuel tanks instead of bombs.
The aircraft was powered by two Pratt & Whitney R-2800 Double Wasp radial engines in nacelles slung under the wing, driving four-bladed propellers.
The engines were manufactured at the Ford Dearborn Engine plant in Dearborn, Michigan.
The wings were of low aspect ratio and relatively small in area for an aircraft of its weight, giving the required high performance, but also resulting in a wing loading of 53 lb/sq ft (260 kg/m2) for the initial versions, which at the time was the highest of any aircraft accepted for service by the Army Air Corps, until the introduction of the Boeing B-29 Superfortress, with the then-astonishing wing loading of 69.12 lb/sq ft (337.5 kg/m2) (although both would be considered lightly loaded by the standard of combat aircraft of the next decade).
The first B-26, with Martin test pilot William K. “Ken” Ebel at the controls, flew on 25 November 1940 and was effectively the prototype.
Deliveries to the U.S. Army Air Corps began in February 1941 with the second aircraft, 40-1362.
In March 1941, the Army Air Corps started Accelerated Service Testing of the B-26 at Patterson Field, near Dayton, Ohio.
The first 201 planes were ordered based upon design alone.
Prototypes were not characterized with the usual “X” or “Y” designations.
They had Pratt & Whitney R-2800-5 engines.
Armament consisted of two .30 calibre and two .50 calibre machine guns.
(The last model was armed with nearly three times that number.)
Incorporated changes made on the production line to the B-26, including upgrading the two .30 calibre machine guns in the nose and tail to .50 calibre.
A total of 52 B-26As were delivered to the Royal Air Force, which were used as the Marauder Mk I.
Model with further improvements on the B-26A, including revised tail gunner’s glazing.
Nineteen were delivered to the Royal Air Forces as the Marauder Mk.IA.
AT-23A or TB-26B
208 B-26Bs converted into target tugs and gunnery trainers designated JM-1 by the US Navy.
Single tail gun replaced with twin guns; belly-mounted “tunnel gun” added.
Pratt & Whitney R-2800-41 radials.
Larger carburettor intakes; upgrade to R-2800-43 radials.
B-26B-10 through B-26B-55
Beginning with block 10, the wingspan was increased from 65 feet (20 m) to 71 feet (22 m) and flaps were added outboard of the engine nacelle to improve handling problems during landing caused by high wing loads.
The vertical stabilizer height was increased from 19 feet 10 inches (6.05 m) to 21 feet 6 inches (6.55 m).
Armament was increased from six to twelve .50 calibre machine guns; this was done in the forward section so that the B-26 could perform strafing missions.
The tail gun was upgraded from manual to power operated.
Armor was added to protect the pilot and co-pilot. (1,242 built)
12 B-26Bs were converted into transport aircraft (all were delivered to the US Marine Corps for use in the Philippines).
Designation assigned to those B-26Bs built in Omaha, Nebraska instead of Baltimore, Maryland.
Although nominally the B-26B-10 was the first variant to receive the longer wing, it was actually installed on B-26Cs before the B-26B-10, both being in production simultaneously.
A total of 123 B-26Cs were used by the RAF and SAAF as the Marauder Mk II.
Approximate cost then
$138,551.27/aircraft (1,210 built)
Originally designated AT-23B.
Trainer modification of B-26C.
Approximately 300 modified
Modified B-26 used to test hot air de-icing equipment, in which heat exchangers transferred heat from engine exhaust to air circulated to the leading and trailing edges of the wing and empennage surfaces.
This system, while promising, was not incorporated into any production aircraft made during World War II.
Modified B-26B constructed to test the effectiveness of moving the dorsal gun turret from the aft fuselage to just behind the cockpit.
The offensive and defensive abilities of the B-26E were tested in combat simulations against normal aircraft. Although the tests showed that gains were made with the new arrangement, they were insignificant.
After a cost analysis, it was concluded that the benefit did not justify the effort needed to convert production lines for the new turret position.
Angle-of-incidence of wings increased by 3.5º; fixed .50 calibre machine gun in nose removed; tail turret and associated armour improved.
The first B-26F was produced in February 1944.
One hundred of these were B-26F-1-MAs.
Starting with 42-96231, a revised oil cooler was added, along with wing bottom panels redesigned for easier removal.
A total of 200 of the 300 aircraft were B-26F-2s and F-6s, all of which were used by the RAF and SAAF as the Marauder Mk III.
The F-2 had the Bell M-6 power turret replaced by an M-6A with a flexible canvas cover over the guns.
The T-1 bombsight was installed instead of the M-series sight.
British bomb fusing and radio equipment were provided.
B-26F with standardized interior equipment.
A total of 150 bombers were used by the RAF as the Marauder Mk III.
B-26G converted for crew training. Most, possibly all, were delivered to the United States Navy as the JM-2.
Test aircraft for tandem landing gear and nicknamed the “Middle River Stump Jumper” from its “bicycle” gear configuration, to see if it could be used on the Martin XB-48.
A small number of JM-1s were converted into photo-reconnaissance aircraft for the US Navy.
British designation for 52 B-26As for the Royal Air Force.
British designation for 19 B-26Bs for the Royal Air Force.
British designation for 123 B-26Cs for the Royal Air Force; 100 passed on to South African Air Force and supported invasion of Italy
British designation for 200 B-26F and 150 B-26G for the Royal Air Force and South African Air Force.
With the exception of the B-26C, all models and variants of the B-26 were produced at Martin’s Middle River, Maryland manufacturing plant.
The B-26C was built at the Martin plant in Omaha, Nebraska.
58 ft 3 in (17.75 m)
71 ft 0 in (21.64 m)
21 ft 6 in (6.55 m)
658 sq ft (61.1 m2)
24,000 lb (10,886 kg)
37,000 lb (16,783 kg)
2 × Pratt & Whitney R-2800-43 Double Wasp,
18-cylinder radial piston engines,
2,000–2,200 hp (1,500–1,600 kW) each
4-bladed constant-speed feathering propellers
287 mph (462 km/h, 249 kn) at 5,000 feet (1,500 m)