The Martin B-26 "Marauder"

The Martin B-26 "Marauder"

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The Martin B-26

The B-26, like the B-25, was ordered into production based on the design alone. No prototype aircraft were built, although the first four production aircraft were used for flight testing. The Glenn L. Martin Company responded to the Army Air Corps Circular Proposal 39-640 by submitting its Model 179 design. Initial contract awards were given to Martin to build 201 B-26s and to North American for 184 B-25s.

The B-26 went from design concept in mid-1939 to flying aircraft in less than two years when it flew for the first time on 25 November 1940. Initial flight testing continued for three months. The 22nd Bomb Group based at Langley Field, Virginia was the first unit to receive the aircraft in February 1941.

The Aircraft was powered by two Pratt & Whitney R-2800 radial engines of 1,850 hp. each. The wing of the B-26 was relatively small making handling the aircraft tricky at landing speeds. Initial armament consisted of a power dorsal turret with two .50-cal. machine guns and a .30-cal. machine gun in the nose and another in the tail. Up to 4,800 pounds of bombs could be carried in the bomb bay.

TYPE
B-26 Number Built/Converted
201 Remarks
Design to production; no prototypes

Notes:

Serial numbers: 40-1361 to 40-1561

The first four B-26s were used for service tests before delivery to the 22nd Bomb Group.

SPECIFICATIONS
Span: 65 ft. 0 in.
Length: 56 ft. 0 in.
Height: 19 ft. 10 in.
Weight: 32,000 lbs. (max.)
Armament: Two .30-cal. and two .50-cal. machine guns plus 4,800 lbs. of bombs
Engines: Two Pratt & Whitney R-2800-5 "Double Wasp" radials of 1,850 hp. each (take-off power)
Crew: 7

PERFORMANCE
Maximum speed: 315 mph. at 15,000 ft.
Cruising speed: approximately 265 mph.
Range: 1,000 miles w/ 3,000 lbs. bomb load; 2,200 miles (max.)
Service Ceiling: 25,000 ft.

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The Martin B-26

The Pratt And Whitney R-2800-21 Engine

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The R-2800-21 Engine

The Pratt & Whitney R-2800 Double Wasp was an aircraft engine, and part of the long-lived Wasp family. It was a two-row, 18-cylinder, air-cooled radial design. Displacement was 2,804 cubic inches (46 liters); bore and stroke were 5.75" and 6".

The R-2800 is considered one of the premier radial piston engines ever designed. It became legendary when used in several aircraft during World War II, notably the F4U Corsair, P-47 Thunderbolt, and the Grumman F6F Hellcat. During the war years, Pratt & Whitney were always coming up with new ideas to upgrade this already powerful workhorse, most notably water injection to give emergency power in combat.

After World War II, the engine was used in the Korean War, and surplus World War II aircraft powered with the Double-Wasp served with other countries well past the Korean War, some being retired as late as the latter part of the 1960s when the aircraft were replaced. The R-2800 also powered post-war propliners from Douglas, Lockheed and Martin. Today, more than 60 years after the first Double Wasp was built, it is still used in many restored vintage aircraft in air shows, and sees frequent service worldwide on such aircraft as the Canadair CL215 water-bomber.

The Pratt and Whitney R-2800 Double Wasp

The Martin B-26 "Marauder"

Joe Baugher

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A-26 cockpit interior

The Martin B-26 Marauder was one of the most controversial American combat aircraft of the Second World War. It was primarily used in Europe, and was in fact numerically the most important USAAF medium bomber used in that theatre of action. However, on four occasions, investigation boards had met to decide if the development and production of the Marauder should continue. The Marauder survived all attempts to remove it from service, and by 1944, the B-26s of the US 9th Air Force had the lowest loss rate on operational missions of any American aircraft in the European theatre, reaching a point less than one half of one percent.

Despite its high landing speed of 130 mph, which remained essentially unchanged throughout the entire production career of the B-26 in spite of numerous modifications made to reduce it, the Marauder had no really vicious flying characteristics and its single-engine performance was actually fairly good. Although at one time the B-26 was considered so dangerous an aircraft that aircrews tried to avoid getting assigned to Marauder-equipped units and civilian ferry crews actually refused to fly B-26s, it turned out that the Marauder could be safely flown if crews were adequately trained and knew what they were doing. It nevertheless did demand somewhat of a higher standard of training from its crews than did its stablemate, the B-25 Mitchell. However, once mastered, the B-26 offered a level of operational immunity to its crews unmatched by any other aircraft in its class.

A total of 5157 B-26 Marauders were built. Although on paper the B-26 was a more advanced aircraft than its stablemate, the North American B-25 Mitchell, it was built in much fewer numbers because it was more expensive to manufacture and had a higher accident rate.

One of the most commonly-asked questions is the difference between the Martin B-26 Marauder and the Douglas B-26 Invader. They were two completely different aircraft and had been designed to completely different requirements. The Douglas B-26 Invader had been originally been designated A-26, and was a twin-engined attack bomber intended as a successor to the Douglas A-20 Havoc. In 1948, the newly-independent Air Force decided to eliminate the A-for-Attack series letter as a separate designation, and the A-26 Invader was redesignated B-26, in the bomber series. There was no danger of confusion with the Martin B-26 Marauder, since this aircraft was by that time no longer in service with the US Air Force.

The history of the Martin Marauder dates back to early 1939. Both the North American B-25 Mitchell and the Martin B-26 Marauder owe their origin to the same Army Air Corps specification. On March 11, 1939, the Air Corps issued Proposal No. 39-640 for the design of a new medium bomber. According to the requirements listed in the specification, a bombload of 3000 pounds was to be carried over a range of 2000 miles at a top speed of over 300 mph and at a service ceiling exceeding 20,000 feet. The crew was to be five and armament was to consist of four 0.30-inch machine guns. The proposal called for either the Pratt & Whitney R-2800, the Wright R-2600, or the Wright R-3350 radial engine.

Requests for proposals were widely circulated throughout the industry. Proposals were received from Martin, Douglas, Stearman, and North American. The proposal of the Glenn L. Martin company of Middle River, Maryland (near Baltimore) was assigned the company designation of Model 179. Martin assigned 26-year old aeronautical engineer Peyton M. Magruder as Project Engineer for the Model 179. Magruder and his team chose a low-drag profile fuselage with a circular cross section. Since the Army wanted a high maximum speed but hadn't specified any limitation on landing speed, the team selected a high-mounted wing with a wingspan of only 65 feet. Its small area gave a wing loading of more than 50 pounds per square foot. The wing was shoulder-mounted to leave the central fuselage free for bomb stowage. The wings were unusual in possessing no fillets. The engines were to be a pair of 1850 hp Pratt & Whitney R-2800-5 Double Wasp air-cooled radials, which were the most powerful engines available at the time. Two-speed mechanical superchargers were installed in order to maintain engine power up to medium altitudes, and ejector exhausts vented on each side of the closely-cowled nacelles. The engines drove four-bladed 13 foot 6 inch Curtiss Electric propellers. Large spinners were fitted to the propellers, and root cuffs were added to aid in engine cooling.

The armament included a flexible 0.30-inch machine gun installed in the tip of a transparent nose cone and operated by the bombardier. Two 0.50-inch machine guns were installed in a Martin-designed dorsal turret located behind the bomb bay just ahead of the tail. This was the first power-operated turret to be fitted to an American bomber. Another 0.30-inch flexible machine gun was installed in a manually-operated tunnel position cut into the lower rear fuselage. There was a 0.50-inch manually-operated machine gun installed in a pointed tailcone. The tail gunner had enough room to sit in an upright position, unlike the prone position that had been provided in the early B-25.

There were two bomb bays, fore and aft. The bomb bay doors were unusual in being split in tandem, the forward pair folding in half when opened and the aft set being hinged normally to open outward. Two 2000-lb bombs could be carried in the main bomb bay, but up to 4800 pounds of smaller bombs could be carried if the aft bay was used as well.

Detailed design of the Model 179 was completed by June of 1939. On July 5, 1939, the Model 179 was submitted to a Wright Field Board. The Martin design was rated the highest of those submitted, and on August 10, 1939, the Army issued a contract for 201 Model 179s under the designation B-26. This contract was finally approved on September 10. At the same time, the competing North American NA-62 was issued a contract for 184 examples under the designation B-25. Since the design had been ordered "off the drawing board", there was no XB-26 as such.

Although the first B-26 had yet to fly, orders for 139 B-26As with self-sealing tanks and armor were issued on September 16. Further orders for 719 B-26Bs on September 28, 1940 brought the total B-26 order to 1131 aircraft.

Early wind tunnel test models of the B-26 had featured a twin tail, which designers thought would provide better aerodynamic control. This was dropped in favor of a single fin and rudder so that the tail gunner would have a better field of view.

The B-26 had a semi-monocoque aluminum alloy fuselage fabricated in three sections. The fuselage had four main longerons, transverse circular frames, and longitudinal stringers covered by a metal skin. The mid section with the bomb bays was built integrally with the wing section. The retractable tricycle landing gear was hydraulically actuated. The nosewheel pivoted 90 degrees to retract into the nose section, and the mainwheels folded backwards into the engine nacelles. The tail fins were of smooth stressed skin cantilever structure. The elevators were covered with metal skin, but the rudder was fabric covered.

The first B-26 (c/n 1226, USAAF serial 40-1361) took off on its maiden flight on November 25, 1940, with chief engineer and test pilot William K. Ebel at the controls. The first B-26 initially flew without any armament fitted.

The first 113 hours of flight testing went fairly well, and there were few modifications needed. However, a slight rudder overbalance required that the direction of travel of the trim tabs be reversed.

Since there was no prototype, the first few production aircraft were used for test purposes. On February 22, 1941, the first four B-26s were accepted by the USAAF. The first to use the B-26 was the 22nd Bombardment Group (Medium) based at Langley Field, Virginia, which had previously operated Douglas B-18s.

A series of failures of the front wheel strut resulted in a delay in bringing the B-26 to full operational status. Although the forward landing gear strut was strengthened in an attempt to correct this problem, the true cause was an improper weight distribution. The manufacturer had been forced to deliver the first few B-26s without guns, and had trimmed them for delivery flights by carefully loading service tools and spare parts as ballast. When the Army took the planes over, they removed the ballast without replacement and the resultant forward movement of the center of gravity had multiplied the loads on the nosewheel, causing the accidents. The installations of the guns corrected the problem.

The last B-26 was delivered in October of 1941. That month, the Martin Middle River production line shifted over to the B-26A version.

Serials of Martin B-26 Marauder:

40-1361/1561 Martin B-26 Marauder

Specification of Martin B-26 Marauder:

Engines: Two Pratt & Whitney R-2800-5 Double Wasp air cooled radial engines, rated at 1850 hp each. Performance: Maximum speed 315 mph at 15,000 feet. Cruising speed 265 mph. An altitude of 15,000 feet could be attained in 12.5 minutes. Service ceiling 25,000 feet. Range was 1000 miles at 265 mph with a 3000-pound bombload. Weights: 21,375 pounds empty, 32,025 pounds gross. Dimensions: Wingspan 65 feet 0 inches, length 56 feet 0 inches, height 19 feet 10 inches, wing area 602 square feet. Armament: One flexible 0.30-inch machine gun installed in the tip of a transparent nose cone and operated by the bombardier. Two 0.50-inch machine guns in a Martin-designed dorsal turret located behind the bomb bay just ahead of the tail. One 0.30-inch flexible machine gun was installed in a tunnel position in the lower rear fuselage. One flexible 0.50-inch machine installed in a tail position. The maximum bombload was 5800 pounds.

The Widow Maker

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In preparation for large-scale introduction of the Marauder into combat, the USAAF had set up B-26 Transition Training Fields at MacDill Field, Tampa, Florida and at Barksdale Field, Shreveport, Louisiana. Nine new USAAF medium bomber groups had been activated in 1942 as Marauder-equipped units.

Unfortunately, many of the pilots trying to master the Marauder at these fields had no previous twin-engined experience. In 1942, a series of training accidents took place stateside which placed the future of the entire Marauder program in doubt. Most of these accidents took place during takeoff or landing. The increases in weight that had been gradually introduced on the production line had made the wing loading of the Marauder progressively higher and higher, resulting in higher stalling and landing speeds. Veteran pilots in combat overseas had enough experience that they could handle these higher speeds, but new trainees at home had serious problems and there were numerous accidents, causing the Marauder to earn such epithets as "The Flying Prostitute", "The Baltimore Whore", "The Flying Vagrant", or "The Wingless Wonder", these names being given because the B-26's small wing area appeared to give it no visible means of support. Other derisive names being given to the B-26 were "The Widow Maker", "One-Way Ticket", "Martin Murderer", "The Flying Coffin", "The Coffin Without Handles", and the "B-Dash Crash". In particular, there were so many takeoff accidents at MacDill Field at Tampa, FL during early 1942 that the phrase "One a Day Into Tampa Bay" came to be a commonplace lament.

While it was true that the wing loading of the B-26 was rather large and the stalling speed was well beyond what most of the trainees were used to, the primary problem with the B-26 was the propellers, which tended to runaway and feather during takeoff on a regular basis. The low speed of the planes as they cleared the runway on takeoff over Tampa Bay plus th drage of the feathered props made for a dangerous combination. Typically, a plane so affected would suddenly flip over toward the feathered prop--since the plane was still at low altitude there was little time for corrective action and the plane would quickly plunge into the bay.

The USAAF was concerned about the high accident rate and seriously considered withdrawing the Marauder from production and service. The US Senate's Special Committee to Investigate the National Defense Program (better known as the Truman Committee, after its chairman, Sen. Harry S Truman of Missouri), which had been charged with ferreting out corruption, waste, and mismanagement in the military procurement effort, also began looking into the Marauder's safety record. In July the Committee recommended that B-26 production be stopped. However, combat crews in the South Pacific were more experienced and were not having any particular problems with the airplane, and they went to bat for the Marauder. They exerted pressure, and the USAAF decided to continue with production of the Marauder.

However, by September of 1942, the situation had gotten even worse and training accidents had become even more frequent. By that time, the reputation of the Marauder had gotten so bad that civilian crews contracted to ferry USAAF aircraft to their destinations were often quitting their jobs rather than having to ferry a B-26. The Air Safety Board of the USAAF was forced to initiate an investigation into the cause. In October, the Truman Committee was again on the warpath and once again recommended that production of the B-26 be discontinued.

USAAF commanding General Henry. H. Arnold directed that Brig. General James H. Doolittle (fresh from his famous Tokyo raid) investigate the problem with the B-26 personally. Doolittle had recently been given command of the B-26-equipped 4th Medium Bombardment Wing, which was scheduled to take part in the invasion of North Africa.

Both General Doolittle and the Air Safety Board concluded that there was nothing intrinsically wrong with the B-26, and there was no reason why it should be discontinued. They traced the problem to the inexperience of both aircrews and ground crews, and also to the overloading of the aircraft beyond the weight at which it could be safely flown on one engine only. Almost immediately after the Marauder had entered service, it had been found necessary to add more and more equipment, armament, fuel, and armor, driving the gross weight steadily upwards. By early 1942, the B-26 had risen in normal gross weight from its original 26,625 pounds to 31,527 pounds with no increase in power. It had been found that many of the accidents had been caused by engine failures, which were in turn caused by a combination of poor maintenance by relatively green mechanics and a change from 100 octane fuel to 100 octane aromatic fuel, which damaged the diaphragm of the carburetors. Many of the B-26 instructors were almost as green as the pilots they were trying to train, and did not know themselves how to fly the B-26 on one engine only, and so could not teach the technique to their students.

General Doolittle sent his technical adviser, Captain Vincent W. "Squeak" Burnett, to make a tour of OTU bases to demonstrate how the B-26 could be flown safely. These demonstrations included single-engine operations, slow-flying characteristics, and recoveries from unusual flight attitudes. Capt Burnett made numerous low altitude flights with one engine out, even turning into a dead engine (which aircrews were warned never to do), proving that the Marauder could be safely flown if you knew what you were doing. General Doolittle himself carried out some demonstration flights with the B-26 in which he cut an engine on takeoff, rolled over, flew the plane upside down at an extremely low altitude for a distance, and then righted it safely. Martin also sent engineers out into the field to show crews how to avoid problems caused by overloading, by paying proper attention to the plane's center of gravity.

However, the decision was made to increase the wing area in order to lower the wing loading, reducing the takeoff and landing speeds and hopefully cutting down on the number of takeoff and landing accidents.

The new wing was first introduced on the B-26C production block at Omaha, and did not appear on the B-26B line at Baltimore until the introduction of the B-26B-10-MA production block, which first appeared in January of 1943. The wing span increased from 65 to 71 feet and area increased from 602 to 658 square feet. A taller fin and rudder was introduced to maintain stability with the larger wing, increasing overall height from 19 feet 10 inches to 21 feet 6 inches.

However, the advantages of the reduced wing loading were partially offset by an increase in gross weight to 38,200 pounds as the result of the fitting of additional armament. A total of twelve 0.50-inch machine guns were now carried. These comprised a flexible 0.50-inch nose gun with 270 rounds, a single fixed gun on the starboard side of the nose with 200 rounds, two "package" guns on each side of the fuselage below the cockpit with 200-250 rpg, two 0.50-inch guns in the rear dorsal turret, two 0.50-inch guns in the beam, and two 0.50 inch guns in the tail. Nevertheless, at a takeoff weight of 36,000 pounds, the takeoff run was reduced from 3150 to 2850 feet. However, the larger wing area resulted in a decrease in maximum speed from 289 to 282 mph.

Even before all the design changes had been put on the production line, the efforts of the Army and Martin to improve training began to pay off, and accidents at training fields began to fall off, and within a month had reached a fairly low level. The Truman Committee finally relented, and stopped its demands for the cessation of Marauder production. Nevertheless, the derogatory nicknames still persisted, and word had not gotten down to the grass roots level that the problems with the B-26 had been largely corrected. Pilot students still believed that the B-26 was a deathtrap, and very few graduates requested assignment to a B-26 group. A number of pilots still refused to fly the plane even in spite of the lowered accident rate, and had to be reassigned to other units.

Joe Baugher

Martin B-26A "Marauder"

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Martin B-26A

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' 3" 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.

TYPE
B-26A

Number Built/Converted
139

Remarks
Imp. B-26; .50-cal. mgs. in nose and tail

41-7345/7365 Martin B-26A Marauder 41-7366/7367 Martin B-26A-1 Marauder 41-7368 Martin B-26A Marauder 41-7369/7430 Martin B-26A-1 Marauder 41-7431 Martin B-26A Marauder 41-7432/7476 Martin B-26A-1 Marauder 41-7477/7483 Martin B-26A-1 Marauder

41-17544/17624 Martin B-26B Marauder 41-17625 Martin B-26B-3-MA Marauder 41-17626/17851 Martin B-26B Marauder 41-17852/17946 Martin B-26B-2-MA Marauder 41-17947/17973 Martin B-26B-3-MA Marauder 41-17974/18184 Martin B-26B-4-MA Marauder 41-18185/18334 Martin B-26B-10-MA Marauder 41-31573/31672 Martin B-26B-15-MA Marauder 41-31673/31772 Martin B-26B-20-MA Marauder 41-31773/31872 Martin B-26B-25-MA Marauder 31773 was *Flak Bait*, the first Allied bomber in the ETO to complete 200 sorties. Nose section is on display at NASM. 41-31873/31972 Martin B-26B-30-MA Marauder 41-31973/32072 Martin B-26B-35-MA Marauder 42-43260/43357 Martin B-26B-40-MA Marauder 42-43358/43359 Martin AT-23A B-26B modified as unarmed target tug 42-43360/43361 Martin B-26B-40-MA Marauder 42-43362/43458 Martin AT-23A B-26B modified as unarmed target tug 42-43459 Martin B-26B-40-MA Marauder 42-95629/95737 Martin AT-23A B-26B modified as unarmed target tug 42-95738/95828 Martin B-26B-45-MA Marauder 42-95829/96028 Martin B-26B-50-MA Marauder 42-96029/96228 Martin B-26B-55-MA Marauder

41-34673/34847 Martin B-26C-5-MO Marauder 34681,34869/34693,34695,34702/34742, 34777/34787 converted to B-26C-6-MO 34680 modified as "XB-26E" 41-34848/34907 Martin B-26C-10-MO Marauder 41-34908/34997 Martin B-26C-15-MO Marauder 41-34998/35172 Martin B-26C-20-MO Marauder 41-35173/35372 Martin B-26C-25-MO Marauder 35370/35372 converted to AT-23B 41-35373/35572 Martin B-26C-30-MO Marauder 100 delivered to RAF as Marauder II FB415/FB517 35525/35572 converted to AT-23B 41-35573/35772 Martin B-26C-35-MO Marauder 35598/35620 converted to AT-23B 41/35773/35872 Martin B-26C-40-MO Marauder All converted to AT-23B 42-107471/107496 Martin AT-23B 42-107497/107830 Martin B-26C-45-MO Marauder 42-107831/107855 Martin AT-23B

43-34115/34214 Martin B-26G-1-MA Marauder 43-34215/34414 Martin B-26G-5-MA Marauder 43-34415/34539 Martin B-26G-10-MA Marauder 43-34540/34614 Martin B-26G-11-MA Marauder For RAF as Marauder III HD602/HD676 44-67805/67954 Martin B-26G-15-MA Marauder 67945/67954 converted to TB-26G-15-MA 44-67955/67969 Martin TB-26G-20-MA Marauder 44-67970/67989 Martin B-26G-20-MA Marauder 44-67990/68064 Martin B-26G-21-MA Marauder For RAF as Marauder III HD677/HD751 44-68065/68104 Martin B-26G-20-MA Marauder 44-68105/68254 Martin B-26G-25-MA Marauder 68221 modified as XB-26H 68222/68253 converted to TB-26G.

TYPE B-26C	Number Built/Converted 1210	Remarks Omaha, NE built B-26B
Notes: Serial numbers: 41-34673 to 41-35370; 41-35372; 41-35374 to 41-35515; 41-35517 to 41-35538; 41-35540; 41-35548 to 41-35551; 41-35553 to 41-35560; 42-107497 to 107830 Most of the serial number 'holes' (above) were allotted to AT-23B (TB-26C) production. 615 -C models were canceled because of war's end. Great Britain received 123 B-26Cs as Marauder Mk.II (FB 400 to FB 522)

Specification of Martin B-26B Marauder (B-10 to B-55):

Serials of Martin B-26 Marauder:

Specification of Martin B-26 Marauder:

Serials of Martin B-26A Marauder:

Specification of Martin B-26A Marauder:

Serials of Martin B-26B Marauder:

Serials of B-26C Marauder:

Serials of B-26F:

Serials of B-26G:

Specification of B-26G:

Sources: