The B-26 Beginnings.

Army Air Corps issues Specification C-213

Development of the B-26 proceeded parallel to the North American B-25 Mitchell both types being designed to a specification for a five-place bombardment aircraft issued 25th January 1939 by the Army Air Corps. Specification C-213 outlined the requirement for a "twin engine medium bombardment airplane." Details of C-213 were given in Circular Proposal 39-640 on 11 March, 1939. It required an operating speed of not less than 250 mph, a top speed of at least 300 mph, a 1,800 mile range with a crew of five, and a service ceiling of no less than 25,000 feet. Specified as well was a bomb load of either four 1,000-pound bombs, two 2,000-pound bombs, six 600-pounders, twelve 300-pounders, or thirty 100-pounders.

The aircraft was to have the load-carrying capacity of a bomber and the speed plus maneuverability of a fighter. It was to have twin engines and a tricycle landing gear.

Due to the urgency in procuring a suitable aircraft, for the first time, the Air Corps stated that a prototype need not be built and tested. The winning design would be contracted for and manufacturing started right off the drawing board. The first unit would be a production version and the rest were to roll off the assembly line henceforth.

Bid Selection is made by the Army Air Corps

Acceptable bids were submitted by four manufacturers with each firm providing up to 15 design variations. The four contenders were: The Glenn L. Martin Co., North American Aviation, Inc., Douglas Aircraft Co., and the Stearman Aircraft Division of the Boeing Airplane Co.. Brg. Gen. Jacob E. Fickel headed the C-213 Evaluation Board for the Air Corps.

A point-rating system of pertinent factors was the "Method of Evaluation" as outlined by Circular Proposal 39-640. Evaluation of the best designs from the four different companies was performed and the Martin Model 179 Bid No. 6 was the champion by a wide margin beating out the North American P-442-D4, Douglas' B-23, and the Stearman P-23.


	The Glenn L. Martin Company had a long and distinguished record of building quality bombardment aircraft.

Many factors explained why the Martin design won:

Top promised performance with a guarantee of a top speed of 322 mph, a 266 mph cruising speed, and a 1,800 mile range.
Outstanding design.
Proven "reduced to practice" engineering & production details.
The Martin Company's long track record in bomber manufacturing.
Guarantee that it could deliver the 1st article in 9 months and 204 aircraft in 23 months - and the Board's belief that it could do it!

The winning bid specified that the propellers were to be the newest four-bladed 13 ft. 6 in. Curtiss Electrics powered by the Pratt & Whitney R-2800 engine. The R-2800 "Double Wasp" had a 2,800 cu. in. displacement and could generate 1,850 horsepower at takeoff and 1,500 mph at 14,000 feet. The engine had just passed Type tests and was an American first - no other air-cooled engine come close to such figures.

The Winning Martin Model 179 Design


Martin Bombardment Airplane Model 179

TALK ABOUT CLASS! The martin design was love at first sight. It was the quintessential two engined air racer - a "doing one hundred miles an hour standing on the ground" design. The aircraft manifested the limits of the aerodynamic state of the art and was by far the most aesthetically appealing of all bids submitted.

Initial design features included:

Circular fuselage to provide maximum interior space, minimum friction, and manufacturing ease.
Very short, broad-chord, and shoulder-high wings with only a 1.3 degree dihedral that made it practically straight. High mounting of the wings was necessary to provide clearance for the 13 1/2 foot Curtiss props.
Two end-to-end bomb bays to accommodate the thirty 100-pound requirement. The aft bomb bays doors were to fold up in a unique "accordion style" to give sufficient ground clearance for bomb loading and the rear opened in the more conventional "clamshell" fashion.
Four .30-caliber machine guns. One each in the: nose, top turret, ventral turret, and tail.
Long underslung engine nacelles of similar aerodynamic profile as the fuselage. Large spinners were attached to the props to fair them smoothly into the cowlings.
Self-sealing "Mareng" fuel tanks of 360 gal. capacity were inboard of each engine nacelle and 121 gal. auxiliary tanks were located outboard of the engines.
Wing aspect ratio (relationship of span to chord) was extremely low at 7.05 to keep wing weight down.
Wing loading (gross weight divided by wing area) was extremely high at 45 pound per square foot. This yielded a stall speed of 97 mph - pilots at the time considered coming in at anything over 70 mph awfully "hot" - for a fighter plane.
Twin tail with tricycle landing gear.
Landing & takeoff speeds/distances greater than any plane flying at that time.

Four 30 caliber guns had been specified for the original armament, but this was increased when Martin developed a power-operated deck gun turret, the first such turret to go into American production.

Self-sealing fuel tanks and 555 lbs. of armor were specified for a B-26A version added on option to the original contract, and by 30th September 1940, the Army decided to include these features on all B-26's under construction.

Although the first B-26 had yet to fly, the orders for 139 B-26A's on 16th September and 791 B-26B's on 28th September 1940 brought the total on order to 1,131 aircraft. No prototype, as such, was planned because of the Army's desire to get its new medium bombers into production.

On 25th November 1940, chief engineer and test pilot William K. Ebel lifted 40-1361, the first B-26, on its maiden flight. Its streamlined form, from the plexiglass nose cone to the tail cone behind the single rudder, earned immediate attention as a virtual "flying torpedo".

The original contract specification was for an empty weight of 19,250 lbs. and gross weight of 26,625 lbs. with a guaranteed performance of 323 m.p.h. top speed, 26,440 feet service ceiling and range of 1,800 miles. The actual B-26 aircraft weighed 21,375 lbs. empty and 27,200 lbs. gross in design condition. Top speed was 315 m.p.h. at 15,000 feet, service ceiling 25,000 feet and range was 1,000 miles at 265 m.p.h. with 3,000 lb. bomb load and 962 gallons of fuel. Maximum ferry range was 2,200 miles with 1,212 gallons.

Dimensions included a wing span of 65 feet, 602 sq. ft. wing area, 56 feet length and 19 ft. 10 in. height. Effects of the high wing loading were shown in the 2,500 feet takeoff run, 12.5 minutes required to climb to 15,000 feet, and 103 m.p.h. landing speed.

Armament included a 30 caliber flexible gun in the nose operated by the bombardier, two 50 caliber guns in the deck turret, another 30 caliber flexible gun at a bottom opening, and another 50 caliber flexible gun in the tail turret. The tail gunner had room enough to sit upright, unlike the prone position on the earlier B-23 and B-25 types. Ammunition supply included 1,200 30 caliber rounds and 1,200 50 caliber rounds. A pair of 2,000 lb. bombs could be accommodated in the main bomb bay, with up to 4,800 lb. of smaller bombs available if the aft bay was used.

The first 113 hours of testing went well without serious incident, and in February 1941 the first four aircraft were accepted, by the Army Air Corps. At Langley Field, Virginia, the 22nd Bombardment Group (Medium) became the first to use the B-26. But of 66 Martins accepted by June, only 21 had been delivered, with 44 remaining in storage. A series of failures of the front wheel strut caused the delay in bringing the B-26 to operational status. The strut was strengthened but it was discovered that the accidents had been due to improper weight distribution. The manufacturer had to deliver the aircraft without guns, and had trimmed the new B-26's for delivery flights by carefully loading service tools and spare parts in a prescribed manner. When the Army took over, these were removed without replacement ballast. The resultant forward movement of the centre of gravity had multiplied the loads on the nose wheel, causing the accidents.

Addition of the guns corrected the problem, and in October 1941 Martin's production lines completed the original contract and delivered the first B-26A, 41-7345. This model differed from the first mainly by provision for an extra ferry tank in the rear bomb bay. Thirty had the R-2,800-5 Wasps, but 109 delivered with the R-2,800-39 of identical power were known as the B-26A- 1. Weight had increased to 21,741 lbs. empty, 28,367 lbs. gross, and ferry range to 2,600 miles with 1,462 gallons.

In 1942, many of the original B-26's were fitted with the extra ferry tanks, and the B-26 and B-26A mingled in service. These Martins had received the name "Marauder" in October 1941. Some ships had replaced the 30 caliber nose gun with a 50 caliber weapon. Fifty-two B-26A's, serials FK1O9 to FK16O, were assigned to the Royal Air Force with the name "Marauder I". By the time production of the B-26A was completed in April 1942, the Marauder had entered combat.

More to come soon!

Please bear with me. Certain portions of this site are under construction.

[Marauder Variants][Armament][The Pratt & Whitney Double Wasp]

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