B-26 Marauder - Variants
As early as September 1940, orders were issued for new modifications of the "Marauder" - 139 B-26A and 791 B-26B. They implemented improvements planned earlier, but for some reason not implemented on the B-26 or suggested by the first experience of operation. They included protruded rigid fuel tanks instead of the previously used soft ones (this made it the first US army aircraft fully equipped with self-tightening tanks) and approximately 252 kg of armor to protect the crew and the most important pieces of equipment.
On the B-26A, which began to enter the Air Force in October 1941, suspension was introduced for two additional fuel tanks (in the rear bomb bay), and 12, at the fore and tail machine guns. The B-26A was a development of the basic B-26 incorporating changes on the production line. Fittings for mounting an auxiliary fuel tank in the aft bomb bay were added, and the nose and tail .30-cal. machine guns were upgraded to .50-cal. The A model aircraft was 2 feet, 3 inches longer than the initial B-26. The first 30 of 139 A models built had R-2800-5 radial engines installed while the last 109 aircraft had R-2800-39 radials. The -39 fitted aircraft were designated B-26A-1 but were essentially identical to the earlier aircraft. The RAF got 52 B-26A-1s (FK 109 to FK 160) and designated them Marauder Mk. Is.
The first 641 (of 1883) Martin B-26Bs built were basically improved versions of the A model. Changes included replacement of the single .50-cal. machine gun with twin guns in the tail and a tunnel gun mounted in the rear crew entry hatch for increased protection below and behind the aircraft. Block 3 and 4 aircraft had large carburetor intakes necessary for more robust sand filters. Block 4 aircraft had a longer nose wheel strut, which was designed to improve take-off performance by increasing the angle of attack. Late production block 4 aircraft deleted the tunnel gun and replaced it with waist gunner positions location near the tail below the aircraft centerline. Great Britain received 19 B-26B-4s as Marauder Mk.1A. Major changes were incorporated into the B-26B-10 and later including a wing span increase of six feet and a taller vertical stabilizer.
Major changes were incorporated into the B-26 design beginning with the block 10 B model (and block 5 C model). The wing span was increased from 65 to 71 feet to decrease the high wing loading and improve the handling of the aircraft, particularly at landing speeds. The wing was also modified by adding flaps outboard of the engine nacelles to further improve take off and landing performance. The vertical stabilizer was heightened by 20 inches to 21 feet, 6 inches and made the late model B-26s easily distinguished from the "short tail" early models.
Like the B-25, the forward armament of the B-26 was increased for ground strafing missions. The nose featured one fixed and one flexible .50-cal. machine gun while four fixed fuselage-mounted .50-cal. package guns were added just behind and below the cockpit. Differences between late production B models included a switch from manually operated tail guns to powered types, relocation of the waist gunner positions and various engine cowling changes. Many aircraft were modified in the field incorporating improvements from later model production. Armor plating was added to the aircraft's exterior just below and slightly forward of the wind screen to protect the pilot and co-pilot. Block 45 and later B-26Bs had a larger windscreen designed for better forward visibility. 1,883 B-26Bs were built; 1,242 of these were block 10 or later.
The B-26C was the Omaha, Neb., produced version of the B-26B. The first B-26C-5 rolled out of the new plant in August 1942 about 13 months after the order for the C model was placed. Although the C-5 was virtually identical to the Baltimore produced B-26B-10, the block numbers didn't match because of a delay in opening the plant in Nebraska. 1,210 C models were built along with more than 300 AT-23B trainer versions, which were later redesignated TB-26C. 615 C models on contract when the war ended were canceled before delivery. The RAF received 123 B-26C-30s as Marauder Mk. IIs, some of which were transferred to the South African Air Force. Like the B-26B, the C had many design changes incorporated on the production line. For example, the tail turret was changed to a Martin-Bell power type beginning with block 10 C models (and B-26B-20s), which shortened the aircraft by about two feet.
The Martin XB-26D was a modified B-26 used to test hot air deicing equipment. Heat exchangers would transfer heat from engine exhaust gases to air circulated to the leading and trailing edges of the wing and empennage surfaces. The hot air would delay the formation of lift destroying ice on the wings and tail. Hot air deicing was never incorporated into a production B-26, but the basic design is widely used on modern aircraft. The hot air deicing method was also tested on the XB-25E.
The B-26E was a B-26B modified by moving the dorsal (top) turret from the aft fuselage forward to just behind the cockpit. The E model was tested against a standard aircraft in defensive and offensive firepower tests. In a strafing mission, the forward top turret would bring the total firepower to eight .50-cal. machine guns. Although the tests showed the forward turret location to be an improvement, only marginal gains were achieved. Martin engineers along with the Army Air Forces decided the cost and time of converting the production lines was not worth the effort, and the basic B-26 was built with the aft positioned dorsal turret throughout the production run.
The B-26F was an improved version of the B-26B-55-MA. The most significant change for the F model design was the 3.5 degree increase in the wing's angle of incidence -- the wing and engines were tilted slightly up in order to improve take off, landing and low speed performance. Other changes made included the removal of the fixed .50-cal. machine gun in the nose, an improved tail turret with increased armor and ammunition for the gunner, and slightly increased fuel capacity. The RAF received 200 F models (S/N 42-96329 to 42-96528) as Marauder IIIs. The B-26F was manufactured exclusively in Martin's Baltimore plant after the Omaha plant converted to B-29 assembly. The first aircraft was delivered in early February 1944.
The B-26G was the last production model of the series. A total of 893 B-26G combat-ready aircraft were built along with 57 TB-26G crew training aircraft (950 total). The RAF received 150 G models along with 200 B-26Fs, which were all designated Marauder III. Externally, the B-26F and B-26G were identical. The only way to distinguish these two models is by serial number. Interior equipment on the B-26G was standardized and accounts for most of the differences with the F model. The last of more than 5,000 B-26s built (all types) was delivered on March 30, 1945, and named Tail End Charlie "30".
The strange-looking tandem gear, mounted on a U.S. Army Air Forces Martin XB-26H Marauder, nicknamed the "Middle River Stump Jumper", was the Glenn L. Martin Co.'s answer to a problem of stowing heavy, bulky landing gears in the thinner wings required for new multi-jet planes. Two main wheels, fore and aft of the wing, retract into the fuselage, while smaller outrigger wheels on either wing will aid the pilot in balancing the plane while taxiing. Here, the small wheels are located in the engine nacelles. Burning rubber and deep skid marks at the Glenn L. Martin Middle River Airport indicated the severe tests to which the new type tandem gear was put by Martin test pilots.
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