Martin XA-22

Last revised August 20, 2000


In 1937, the Army's Materiel Division began to investigate the possibility of the development of a twin-engined attack bomber with a performance that would greatly exceed that of the single-engined types that were currently in service. In March 1938, the Air Corps issued Circular Proposal Number 38-385 that defined the requirements. Payload was to be 1200 pounds, and range was to be 1200 miles at speeds greater than 200 mph. The Army invited all of the contestants to build prototypes of their designs at their own expense for a design competition. The deadline for the entries would be March 17, 1939.

Proposals were submitted by Bell, Douglas, North American, Boeing-Stearman and Martin. Bell's Model 9 proposal called for an aircraft powered by two liquid-cooled Allison engines. It was withdrawn from the competition before anything could be built. The Douglas entry was the Model 7B, a high-winged monoplane powered by a pair of 1100 hp Pratt & Whitney R-1830 Twin Wasp radials. The North American entry was designated NA-40 by the company and was a high-winged aircraft carrying a crew of five--pilot, copilot, bombardier/navigator, radio operator/gunner, and gunner. Stearman's entry was the Model X-100, which was a three-seat high-winged monoplane powered by a pair of untried Pratt & Whitney R-2180 radials.

Martin submitted its Model 167, a twin-engined mid-wing tail-down monoplane. The aircraft was powered by two Pratt & Whitney R-1830-37 Wasp radials, each rated at 1200 hp for takeoff and 1100 hp at 5000 feet. The Model 167 carried three crewmembers in a narrow fuselage--one pilot, one bombardier in the nose, and a gunner that operated a retractable dorsal turret that was covered by a panel that slid forward when the turret was raised. Armament included four 0.30-inch machine guns in the wings, one 0.30-inch machine gun in the turret, and one 0.30-inch machine gun in a deeply-cut lower position behind the bomb bay. The bomb bay could accommodate 60 30-pound or four 300-pound bombs.

The Model 167 was flown from Baltimore to Wright Field in Ohio on March 14, 1939. It initially flew under the civilian serial number NX22076. Although no aircraft had yet been ordered by the US Army, the gathering war clouds in Europe attracted the attention of the French government to the twin-engined attack aircraft contest. The French government was sufficiently impressed by the Martin entry that on January 26, 1939, the French government placed a contract for 115 aircraft. The French version was designated Model 167F by the company. The Armee de l'Air designation was 167 A-3, the A standing for army cooperation and the -3 identifying a three-seater. The availability of French money made it possible for Martin to build a new plant that was to play a valuable role in B-26 production.

None of the entries initially succeeded in landing any Army contracts. Instead, in April of 1939, the Army called for a new contest in which new design proposals would be requested and evaluated without the need for the construction and testing of prototypes. All of the contestants, including Martin, submitted new bids. On June 30, 1939, the Army decided in favor of the Douglas DB-7, which was a revised version of the Model 7B that had crashed during flight test. 123 examples were ordered under the designation A-20. Glenn L. Martin protested the production contract awarded to the Douglas DB-7 on the grounds that the Model 7B prototype had crashed and was not actually present at the competition. However, he was somewhat consoled by the French contract for the Model 167 which had been placed in January of 1939.

Although the US Army did not order the Model 167 into production, on May 20, 1939, it did arrange to purchase the prototype under the designation XA-22. The serial number was 40-706. Although a few flight tests were carried out, there was no further development.

Specification of Martin XA-22:

Engines: Two Pratt & Whitney R-1830-37 air-cooled radial engines, each rated at 1200 hp for takeoff and 1100 hp at 5000 feet. Performance: Maximum speed 280 mph at 5000 feet. Cruising speed 260 mph. Service ceiling 20,000 feet. Range 750 miles with 1800 pounds of bombs, 1200 miles with 1200 pounds of bombs. 1900 miles maximum range. Dimensions: Wingspan 61 feet 4 inches, length 46 feet 8 inches, height 10 feet 0 inches, wing area 538.5 square feet. Weights: 11,170 pounds empty, 16,00 pounds gross, 17,00 pounds maximum. Sources: Dog of War, Peter Bowers, Airpower, Vol 26, No. 1 (1996) American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday, 1982.

Sources:


  1. American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday, 1982.

  2. Dog of War, Peter Bowers, Airpower, Vol 26, No. 1 (1996)