Marauder Variants
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Span
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B-26
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Externally identical to the B-26, the B-26A had additional Dural armor plate. Goodyear rubber self-sealing fuel tanks replaced the original Mareng ones. Other changes included: 24-volt electrical system, provision for a second releasable 250-gallon gas tank in the forward bomb bay, low pressure oxygen system, and a 100-amp generator. These changes added nearly 2,000 pounds to the weight. The B-26A retained the R-2800-5s, although these were now the Ford license-built version. The AAF ordered that all B-26s off the production line without the changes specified for the B-26A variant be modified to include them. This was accomplished and the B-26 and B-26A became virtually identical in service. |
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Because of the critical shortage of R-2800-5 engines for the B-26As, in late October, 1941, the AAF ordered Pratt & Whitney to divert 200 R-2800 S1A4Gs ("A" engine of 1,850 hp) and 222 R-2800 2SB-Gs ("B" engines of 2,000 hp) from an RAF order to Martin. These converted engines were redesignated by the AAF as R-2800-39s and R-2800-41s respectively. The switch to the -39 engines was made on the Baltimore assembly line starting with aircraft 41-7366. These Marauders were designated B-26A-1s and were otherwise identical to the B-26As. |
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B-26Bs were the first in the series with noticeable external differences. The tail gun position was completely redesigned, with the single .30-caliber machine gun replaced by two 0.50-caliber guns in a new "stepped" tail arrangement. Overall length increased to 58'-3''. Two other visible changes: torpedo racks under the fuselage were to be fitted as factory standard, and the oil cooler air scoop under the cowling was enlarged. Engines were switched from the R-2800-39s of the B-26A-1s back to the R-2800-5s. A total of 100 "pure" B-26Bs were manufactured. The first example was accepted and delivered April 5, 1942. |
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Starting in July, 1942, an eventual total of 207 Baltimore-built B-26Bs, most destined as "final equipment" for North African bound groups, were flown from Middle River to Martin's Omaha Modification Center and reworked there under AAF instructions. So many modifications were made to these planes that unofficially they became known as "B-26B-1s" Nose Plexiglas was structurally strengthened to accommodate a center-line mounted flexible .50-caliber gun. A fixed forward-firing . 50-caliber machine gun was installed in the lower right-hand side of the nose. The two .30-caliber waist guns and the .30-caliber tunnel gun were replaced by flexible Browning . 50-calibers. Two circular scanning lenses were added above each waist gun position. Provisions were made for two more 250-gallon ferry tanks to be fitted in the rear bomb bay. This increased fuel capacity to 1,962 gallons, extended maximum ferry range to 2,850 miles, and raised takeoff weight considerably. The air intakes on top of each engine cowling were changed to much larger ones that would accommodate sand filters. The Plexiglas windows on both sides of the fuselage, next to the radio operator and navigator table, were replaced with "bulged" ones to permit a view downwards. To improve engine cooling--and lessen maintenance difficulties--the large propeller spinners were deleted. |
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Pratt & Whitney began delivering its upgraded 2,000 hp takeoff-rated "Double Wasp" R-2800-41 engine ("B" series) from the British order to Martin-Baltimore during May, 1942. Marauders built with this powerplant were designated B -26B-2s. Ninety-five were so equipped. The first was accepted June 17, 1942. A "whip" antenna for the new VHF radio was fitted to the underside of the B-2 and on subsequent Marauders just aft of the nose wheel door. A number of overseas-bound B-26B-2s received the same modifications at Martin-Omaha as the "B-26B-1s" had. |
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First examples of the slightly-modified Pratt & Whitney R-2800-43 engine (2,000 hp takeoff-rated) became available in the fall of '42, and the Army ordered them installed on 28 Marauders, designated B-26B-3s. Most of the B-26B-3s destined for overseas were also modified at Martin-Omaha as the "B-26B-1s" had been. |
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Production of the B-26B-4 variant commenced at Baltimore with the 431st aircraft of the "B" series in September, 1942. Two hundred eleven were built. The most significant and noticeable change was an attempt to improve takeoff performance by lengthening the nose wheel strut six inches. This gave the B-26B-4 a distinct "nose-up" attitude on the ground. A "bump" had to be built into the nose gear doors to the front to clear the repositioned retracting mechanism. Mechanically operated main wheel landing gear doors were incorporated starting with this variant. Built in three sections, two were closed when the landing gear was extended to cut drag. Retractable circular air ventilators were added beside pilot and co-pilot positions. Weight of the Marauder had been steadily rising with the addition of more equipment and armament. Wing loading, which had been high with the original design, went even higher--to a nearly unsafe 63 lb./sq. ft. The B-26B-4's wing loading was exceeded only by the German Do 217 (64 lb./sq. ft.), highest of all the medium bombers of World War II. Martin- Omaha likewise modified many of the North African-bound B-26B-4s just as It had the "B-26B-1s". In addition, four forward-firing .50-caliber fixed guns in "blisters" were mounted on each side of the fuselage below the radio operator and navigator's compartment. Armament now totaled twelve Colt-Brownings, giving the Marauder as much firepower as a fighter! |
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For the "long wing" Marauder, Martin was ordered to increase wing area to 713 sq. ft. by broadening the chord and lengthening the span to 71 feet. This dropped wing loading to 51.5. A larger tail was also fitted. Overall, the plane was 58'-3" long and sat 21'-6" off the ground. Tread width was nearly 22'. Due to the larger, and heavier, wing and tail assembly, and the additional armament and armor, weight increased by 1,500 pounds to 26,300 pounds basic, 31,200 normal (DGW) and 37,000 loaded. Because of its greater weight and drag, top speed of a "long wing" at 15,000 feet declined to 282 mph and cruising speed dropped to 214 mph. With a load of 4,000 pounds of bombs and 962 gallons of fuel (no bomb bay tanks), the "long wing" had an operating range of 550 miles. A 50-inch tire on a larger wheel replaced the 47-inch one on the main landing gear. A streamlined "bump" in wheel well door covers appeared to accommodate the increased diameter tire. The hydraulic system was improved. Exhaust flame dampers were added. Generators were upped from 100 to 200 amps. Easier access was provided to the nose compartment by reducing the height of the co-pilot's seat. The armament changes Initially done on "B-26B-1s", plus the package guns of the B-26B-4, were made standard. In addition, side waist gun doors were enlarged and moved one station aft to improve the angle of fire down and to the front. Each would slide up and lock open. A single larger circular scanning window, replacing the two smaller ones, was located above each waist door to give the gunner a better view. Bomb racks, bomb hoisting equipment and the bombardiers' position were changed. The optically flat glass In the lower nose transparency was enlarged and elongated. Marauders
built at Omaha were now to have the suffix "MO".
The original B-26Cs from the Nebraska plant were subsequently
redesignated B -26C-05-MOs. One hundred seventy-five
examples were built. Main and nose landing gear doors
(all but one section) were made to close when the gear
was extended from the 61st article on. |
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A unique Marauder weight reduction modification experiment was ordered early in 1943 by the AAF In an attempt to improve landing and takeoff performance. Fifty-nine Omaha-built B-26C-5-MOs, to be assigned as original equipment for the England-bound 323rd Bombardment Group, were substantially lightened. Redesignated B-26C-6-MOs, these Marauders had no co-pilot; his control column, seat, and armor plate were removed, as was some equipment such as the liaison radio set. After the first two Squadrons of the 323rd had ferried these modified Marauders to the U. K. and flown some combat missions, commanders there objected so strenuously to the lack of a co-pilot that the experiment was abandoned. All "single pilot" B-26C-6-MOs were eventually converted back to two-pilot configuration. |
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The last 150 "B" model Marauders (642nd to 791st articles, 41-18185 through 41-18334) from Middle River were made as B-26B-10-MAs, Identical to the B-26C-5- MOs. The first B-10 was accepted January 15, 1943. The suffix "MA" indicated the planes were built at Baltimore. By March, 1943, Martin-Omaha had made the changes required by Martin-Baltimore's Engineering Department and began producing Its B-26C-10-MO model, Identical to the B-26B-10-MA. Sixty were built serialed 41-34848 through 41-34907. |
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The block of 100 Baltimore-built Marauders serialed 41-31573 through 41-3 1672 were designated B-26B-15s. They differed from the B-26B-10 only in having the fixed oxygen system Type A-9 regulator deleted and improved IFF equipment (SCR-595A) fitted. Martin-Omaha also incorporated these same changes in aircraft 41-34908 through 41-34997, designated B-26C-15-MOs. |
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Starting with the B-26B-20-MA and B-26C-20-MO, the hand-held twin-fifty tall gun position was redesigned and fitted with a power-operated electro -mechanical Bell type M-6 turret. The blunt, rounded-off installation visibly changed the Marauder's tail profile and reduced overall length to 56 ft. 1 in. Another noticeable external change was the shorter chord rudder. One hundred B-26B-20-MAs were built along with 175 B-26C-20-MOs. |
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The one hundred B-26B-25-MAs and 200 equivalent B-26C-25-MOs featured more armor plate on the Martin 250CE turret. Some of these aircraft destined for Stateside training and other non-combat uses were not fitted with the Bell tail turret. On the C-25-MOs headed for the MTO, Martin-Omaha fitted a shell collector pan beneath the tail guns. Three B-26C-25-MOs, serials 41-35370 through 41-35372, were converted to AT-23Bs. |
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Starting with this model, a curved piece of armor plate was mounted externally to the left side of the fuselage to protect the pilot. Armor was also added behind the bombardier and around vital mechanical parts of the plane in several locations. One hundred B-26B-30-MAs were built at Baltimore while 200 B-26C-30-MOs were made by Martin-Nebraska. Forty-eight of the B-26C-30-MOs were converted to AT-23Bs, serialed 41-35525 through 41-35572. And 100 C-30s were furnished to the RAF as Marauder IIs, FB 418-517. |
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The carburetor alcohol de-icing system was eliminated and that was the only change in this block of 100 B-26B-35-MAs and 200 identical B-26C-35-MOs. 23 aircraft, 41-35598 through 41-35620, were converted from B-26C-35-MOs to AT-23Bs at Martin-Omaha. |
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A torpedo -firing switch was added to the pilot's control column with this version and the type B-2 Torpedo Director was discontinued. The carburetor air duct was revised for hot air de-icing from the middle of this block (42-43320) forward. One external change on this model was noticeable: "shark nose" ailerons were fitted from 42-43310 on. Martin-Baltimore built 200 B-26B-40-MAs. A total of 141 of these planes were converted to AT-23As, serials 42-43319 through 42-43459. Martin-Nebraska manufactured 100 B-26C-40-MOs and all were subsequently converted to AT-23Bs. |
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On this block of Marauders, the pilot was provided with a ring-and-head sight for his package guns. Increased strength bomb hooks for the B-10 shackles were fitted. IFF radio equipment SCR-695 was supplied and the new SCR-522 VHF Command radio set with accessories was added. The engine fire extinguisher was reinstated as standard. A remote heading compass was fitted. With the requirement for carrying thirty 100-pound bombs dropped by the AAF as a result of combat experience, the Marauder's aft bomb bay was sealed up from this variant on. That bay hereafter held tail gun ammo. A special track was installed to carry the .50-caliber bullets some 30 feet back to the tail gun position. The fixed .50-caliber machine gun In the nose was deleted in the middle of the production run (from 42-95979). A total of 200 B-26B-45-MAs were built. One hundred nine of these aircraft, 42-95629 through 42-95737, were subsequently converted to AT-23As. All told, 359 B-26C-45-MOs were built. The last 26 in the block, serials 42-107856 through 42-107881, were made as AT-23Bs. |
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An emergency mechanical bomb bay door closing arrangement was provided from this block on IFF gear was revised. Lycoming propeller blades began to be fitted from a/c 42-95942. Two hundred B-26B-50-MAs were built at Baltimore. |
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The D-8 bombsight was discontinued with this model and the M-series was fitted instead. Specification changes in the Martin CE 250 top gun turret (optical sight, etc.) were incorporated from a/c 42-96079 on. In a major change, camouflage paint was completely deleted by Martin-Baltimore from 42-96129 on. Two hundred B-26B-55-MAs were manufactured. |
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The B-26F- 1 -MA, which started to come off the Middle River line in February, 1944, featured the last major structural change in the Marauder: wing Incidence (angle to the fuselage) was Increased by 3 1/2 degrees to 7 degrees. The "twisted wing" (besides giving greater propeller ground clearance) Improved lift characteristics, reducing takeoff run length and lowering landing speed. In the air the "F" flew fairly level--the tail was up slightly- -and the plane no longer gave pilots the feeling that It was riding "nose high". Disadvantages: top speed was lowered some to 277 m.p.h. and the new model didn't handle quite as well. Torpedo shackles were deleted from this model on. An all-electric bomb release system was now furnished. Starting with a/c 42-96231, a revised oil cooler with thermostatic control and surge valve was fitted, along with wing bottom panels redesigned for easier removal. Instrument panel changes were made; trailing antenna was made removable. The B-26F-1-MA had provisions for a revised fuel transfer system. Gasoline tanks were redesigned to permit inter-connection, although this system was not actually hooked up on this variant. Up to this time emergency extension of the main landing gear had been left to gravity, but this didn't always work. The "F" was fitted with a mechanical means of lowering the main gear in an emergency. In all, 100 B-26F-1-MAs were built for the USAAF by Martin-Baltimore. |
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These two identical blocks of 100 aircraft each were built for the RAF and SAAF as Marauder IIIs, serialed HD 402 through HD 601. The Bell M-6 power-boost tail turret was deleted from this block forward, replaced by the M-6A, a modified version with a flexible canvas cover over the end of the gun position. Provision was made for fitting optical gun sights on flexible machine guns. The T-1 bombsight was installed instead of the M-series. Provisions for British nose and tail bomb fusing and B-9 shackles were made. Radio equipment was changed to British standards. |
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The B-26G series began being built at Baltimore in March, 1944. It differed from the B-26F only in equipment details. Externally they were identical. An armor "blanket" was added to protect the fuselage from the blast of the package guns. Marauders of this block, at the request of the Ninth Air Force (a/c 43-34190 on) were equipped with the C-1 Automatic Pilot. Partial top-surface camouflage paint was applied at the factory. Inboard and outboard wing fuel tanks were, hereafter, interconnected. Universal "Army/Navy" instead of "Air Corps" equipment was fitted. A larger life raft compartment was provided in the top section of the forward fuselage of the B-26G-1-MA. This compartment took an A-3 or E-2 rubber dinghy, and offered stowage for all required provisions, including a dinghy radio. One hundred B-26G-1-MAs were built. |
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The two hundred B-26G-5-MAs built had only minor hydraulic system changes. |
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One hundred twenty-five of the B-26G-10-MA variant were built for the USAAF while an additional 75 B-26G-11-MAs, went to the RAF as Marauder Ills, HD 602-676. A tail gun shell collector pan was fitted as standard below the position on the bottom of the fuselage. The lock valve cowl flap system was deleted from 43-34575 on. Some planes were furnished with Lycoming prop blades. |
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With this model, the C-1 Automatic Pilot was deleted, along with the portable system outlets. The radio compass was changed. One hundred fifty B-26G-15-MAs were built. The last ten of these aircraft (44-67945 through 44-67954), were designated TB-26-15-MAs after being modified in November, 1944, for training and target-tow duties. |
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Whip-type static dischargers were the only additions to this model, 150 examples of which were made. Fifteen planes of this block (44-67955 through 44-67969) were built as TB-26G-20-MAs. And 75 were designated B-26G-21-MAs (44-67990 through 44-68064) and turned over to the RAF where they were serialled HD 677-751 and called Marauder IIIs. |
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Last variant off the line, the B-26G-25-MA had only a few minor changes to distinguish it from its immediate predecessors. Of the 150 examples, thirty-two (44-68222 through 44-68253) were stripped of armament and operational equipment in March, 1945, to serve as TB-26G-25-MA trainers and target tugs. The last Marauder built left Martin April 18, 1945. It was B-26G-25-MA 44-68254 named "Tail End Charlie" and "30". |
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Text from The Martin Marauder B-26 by Victor C. Tannehill
Copyright(c) 2008 320th History Preservation. All rights reserved.