Certainly one of the most elegant bomber aircraft to appear in the early years of World War II, Martin’s B-26 Marauder stemmed from a US Army Air Corps high-speed medium bomber specification which had been circulated to US manufacturers in January 1939. This called for a number of characteristics which, together, made the US Army requirement very difficult to meet. To accommodate a crew of five, which meant that it must be fairly large, it was required also to be fast and with good high-altitude performance, to have a range in excess of 2,000 miles (3219 km), and be able to carry good defensive armament plus a worthwhile load of bombs.
Martin’s design, by Peyton M. Magruder, was far in advance of competing submissions, and as the company not only guaranteed that performance would be as good as, or better than performance estimates and also promised early production, it was not surprising that this company was chosen to build the USAAC’s new bomber. The startling feature of the contract, awarded in September 1939, lay in the fact that it was for a substantial number of production aircraft (201) ordered ‘straight off the drawing board’, a course then unprecedented in USAAG history. No prototypes or preproduction aircraft were called for, so the first of the Martin Model 179s, designated B-26 by the US Army, flew for the first time on 25 November 1940.
As then flown it was a cantilever shoulder-wing monoplane of all-metal construction, except that all control surfaces were fabric-covered, and the conventional but small-area wing had plain trailing-edge flaps. The fuselage was a near perfect aerodynamic cigar-shape form of circular cross-section, marred only by the ‘step’ of the windscreen, and with a conventional tail unit which had a high-set tailplane. Landing gear was of the retractable tricycle type, the main units retracting forward and upward into the centre of the engine nacelles, and the nosewheel unit aft into the forward fuselage. To provide the necessary performance a new Pratt & Whitney engine had been selected, the 1,850 hp (1380 kW) R-2800-5 Double Wasp, and the two of these each drove a four-blade constant-speed fully-feathering propeller. An innovation was the use of a ‘cuff’ at the root end of each propeller blade, this enabling the normally useless area of each blade to provide extra airflow for improved engine cooling. Initial armament comprised two 0.30 in (7.62 mm) machine-guns, one in the nose position and one in the tailcone, plus two 0.50 in (12.7 mm) guns in an electrically operated dorsal turret, the first powered gun turret to be installed in an American bomber. Maximum bomb load, all carried internally, was as much as 5,800 lbs (2631 kg) for deployment at short range.
Following the first flight, it was not until February 1941 that succeeding production aircraft began to come off the line, and while some of these were diverted for test purposes, there were sufficient available to begin deliveries to the USAAC. This initial equipping of the US Army Air Corps’ squadrons was not without problems, for while they had been supplied with an aircraft which attained the desired high performance specification, this performance had been achieved at the expense of good low speed handling characteristics, leading to what is usually termed a ‘hot’ aeroplane. This made conversion training a difficult and slow process, for even at loaded weights well under maximum the aircraft’s stalling speed was not far below 100 mph (161 km/h), a very high figure for that period.
In spite of this Marauders, as the B-26 had been named in preference to the originally chosen Martian, gradually began to equip USAAF squadrons and as experience was gained a number of modifications were considered to be desirable, resulting in the B-26A of which 139 were built. All had engines of the same power as the B-26, but R-2800-5, -9 and -39 units were installed in different batches. The electrical system was changed from 12-volt to 24-volt, two additional fuel tanks were installed in the bomb bay, provision was made for the carriage of a 22 in (559 mm) torpedo and, as a result of combat reports from the war then being fought in Europe, the nose and tail guns of 0.30 in (7.62 mm) calibre were replaced by similar 0.50 in (12.7 mm) installations. The result of these changes, of course, was to increase the gross weight and also, as a consequence, the problems that were soon to come to a head.
Before that, however, the Japanese on 7 December 1941 attacked Pearl Harbour and, on the following day, the USAAF’s 22nd Bombardment Group was despatched to the Pacific zone, becoming operational initially from northern Australia in April 1942. This unit’s B-26As soon found ready employment in a variety of roles, including unsuccessful torpedo attacks against the Japanese fleet engaged in the Battle of Midway. At about that same time the RAF received three examples of the B-26A for evaluation, these being designated Marauder 1. Successful testing resulted in this type being chosen for tactical use in the North African campaigns, and the additional 48 of this version allocated under Lend-Lease were delivered direct to the Middle East and used first to equip No. 14 Squadron.
While these events had been taking place, a special board of investigation had been set up in the USA, under the chairmanship of Major General Carl Spaatz, to enquire into the abnormally high accident rate associated with the B-26, especially during training, and to decide whether production should be terminated. Fortunately this latter course was not adopted for, with growing experience of how best to handle the Marauder, it was later to have the lowest attrition rate of any American aircraft operated by the US 9th Air Force in Europe. The eventual findings of the investigation board resulted in continuing production, but with some recommendations regarding modifications intended to improve low-speed handling.
During the foregoing enquiry all production had been suspended but soon after it was resumed, in May 1942, Martin began to deliver its first B-26Bs, the major production version of which 1,883 were built. These incorporated initially improvements which combat experience had proved to be necessary, but many other changes were introduced on the line throughout the long manufacturing run. Major items included the installation of 1,920 hp (1432 kW) R-2800-41 or R-2800-43 engines, the introduction of slotted trailing-edge flaps, and a lengthened nosewheel strut to increase wing incidence and so improve take-off characteristics. The most important change, one which had been recommended by the enquiry board, was an increase in wing span/area but this, in fact, achieved nothing because the USAAF immediately upped the gross weight. The comparisons of maximum wing loading are interesting, the B-26’s being 53.16 Ibs/sq ft (259.5 kg/m2), the early B-26B’s 56.48 lbs/sq ft (275.7 kg/m2), and the late B-26B’s 58.05 lbs/sq ft (283.4 kg/m2), which all goes to prove that the initial handling problems were largely those of inexperience. Today little is thought of a wing loading of 149 lb/sq ft (728 kg/m2), and that for a civil transport aircraft, not a ‘hot’ military aeroplane.
The introduction of the larger wing necessitated an increase in vertical tail surface area, achieved by increasing fin and rudder height by 1 ft 8 in (0.51 m). The armament, through a succession of modifications, became almost as potent as that of the USAAF’s heavy bombers, with no fewer than 12 0.50 in (12.7 mm) machine-guns. The increasing demand for Marauders resulted in the establishment of a second production line by Martin at Omaha, Nebraska, which built 1,235 aircraft as B-26Cs from late 1942, these duplicating various batches of the B-26Bs built at Baltimore, Maryland. The D and E designations were taken up by two one-off aircraft: the XB-26D was an experiment in thermal wing de-icing; and the XB-26E was a ‘weight watchers’ version with some 2,000 lbs (907 kg) weight reduction and with the dorsal turret moved forward to a position adjacent to the wing leading edge.
The final production versions were the generally similar B-26F (300 built) and B-26G (893), plus 57 TB- 26Gs without armament and other purely operational equipment to serve as target tugs or trainers. The major difference between these aircraft and the B-26B/B-26Cs which had preceded them lay in a final attempt to improve take-off performance, wing incidence being increased by 3°30′, so giving a noticeable nose-in-the-air look to the engines. There were also some armament and fuel system changes. Last of the B-26 designations was taken by a single XB-26H with tandem bicycle type landing gear with each of the main units carrying twin wheels and an outrigger, for balancing, was housed in each engine nacelle. This experimental installation was made to evaluate a landing gear of this type which was being developed for the Boeing XB-47.
All of the USAAF’s early deployment of the B-26 had been confined to the Pacific theatre, but B-26Bs and B-26Cs began to appear in North Africa during November 1942, equipping 12 squadrons of the 17th, 319th and 320th Bomb1l.rdment Groups of the 12th Air Force, providing admirable support to the Allied ground forces as they followed the bitter but victorious trail to the south of France via Sicily, Italy, Sardinia and Corsica. However, the B-26’s first operation with the 8th Air Force in Europe was disastrous, all 11 aircraft sent to make a low-level attack on installations in the Netherlands failing to return to base. Subsequently, in a tactical role, Marauders went from strength to strength in operations with the USAAF’s 9th Air Force, also in Europe.
Under Lend-Lease the RAF received a total of 522 Marauders, these comprising the Marauder I mentioned above, plus Marauder IA (B-26B), II (B-26C) and III (B-26F/B-26G). Used by the RAF’s Nos. 14, 39, 326, 327 and 454 Squadrons and the South African Air Force’s Nos. 12, 21, 24, 25 and 30 Squadrons, they were deployed most successfully alongside the B-26s of the US 12th Air Force, after initial failure in a torpedo carrying role.
In 1943 the USAAF converted 208 B-26Bs and 350 B-26Cs for use as high-speed target tugs, stripping out all armament and operational equipment, and these were redesignated initially as AT-23A and AT-23B respectively, but subsequently TB-26B and TB-26C. Of these the US Navy acquired 225 AT-23Bs which they designated JM-1, and 47 TB-26Gs, the last Martin production version, as JM-2s.
Nicknames: Widow-Maker; The Flying Coffin; B-Dash-Crash; The Flying Prostitute; The Baltimore Whore (The last two because it had no visible means of support; “Baltimore” because the Martin Company was located there.)
Engines: Two 2,000-hp Pratt & Whitney R-2800-43 Double Wasp radial piston engines.
Weight: Empty 25,300 lbs., Max Takeoff 38,200 lbs.
Wing Span: 71ft. 0in.
Length: 56ft. 1in.
Height: 20ft. 4in.
Maximum Speed: 283mph
Ceiling: 19,800 ft.
Range: 1,100 miles
11 12.7-mm (0.5-inch) machine guns
Up to 4,000 pounds of bombs
Number Built: 5,157