In 1916, Glenn L. Martin withdrew from the Wright-Martin combine that he had been involved with, and struck out on his own. The Glenn L. Martin aircraft company was established in Cleveland, Ohio in late 1917.
One of the first Army contracts landed by the new company was the design a new bomber that would hopefully outperform the British-designed Handley-Page, which was at that time scheduled to be built in the USA by Standard Aircraft of Elizabeth, New Jersey.
The aircraft that emerged was designated MB-1 by the Martin company. It was a wooden, fabric-covered biplane powered by a pair of liquid-cooled 400 hp Liberty 12A engines suspended between the wings. The engines were cooled by a set of radiators situated in the front of the engine mounts just above the propeller shaft. Two bays of struts were outboard of the engines. The fixed mainwheels were aligned on a single axle. The tail consisted of twin rudders, mounted on top of a single horizontal stabilizer. A crew of 3 could be carried, a bombardier in a nose position, a pilot, and a gunner in a position in the upper fuselage just aft of the top wing.. The armament consisted of five 0.30-inch machine guns, two in the nose position, two in the aft fuselage position, plus one firing downward and to the rear through a trapdoor. Maximum bombload was 1040 pounds.
The original contract for six examples was issued on January 17, 1918. It was increased to 50 on October 22, 1918, but then was cut back to ten in January 1919.
The first MB-1 flew on August 17, 1918. A total of ten examples were built, the last being delivered to the US Army Air Service in February of 1920. They were designated GMB by the USAAS, where the letters stood for "Glenn Martin Bomber". Their serials were 39055/39060 and 62948/62951. They were the first American-designed bombers to enter service with the USAAS.
The Martin MB-1 had a good performance for its day. However, the Martin bombers were too late to see any action during World War 1. They formed the nucleus of the first Army bomber squadrons during the immediate postwar years. High power and a relatively small size made the GMB also capable of carrying out the long range observation and the escort fighter roles. The first four were built as observation aircraft, and the next three were built as bombers. The eighth (designated GMT for "Glenn Martin Transcontinental") was a special long-range version capable of 1500-mile range, and the ninth (designated GMC for "Glenn Martin Cannon") was fitted with a 37-mm cannon in the nose that replaced the standard 0.30-in macnine gun. The serial number of the GMC was AS 62951. Another notable modification was the addition of a third engine in the nose of AS 39059.
The last example was completed as a transport by removing all the military equipment, raising the top of the fuselage, and adding cabin windows and seats. The pilot's cockpit was enclosed in a glazed enclosure. It was originally given the designation GMP (for "Glenn Martin Passenger"), but was later designated T-1, where the T was in the T-for-Transport series.
Six modified MB-1s were turned over to the US Postal Service and flew air mail delivery runs for a short time during the period when the US government took over the delivery of air mail.
So far as I am aware, no MB-1 aircraft survive today.
Serials of the Martin MB-1:
39055/39060 Martin GMB 62948 Martin GMB 62949 Martin GMT 62950 Martin GMC 62951 Martin GMP (T-1)Specification of the Martin MB-1:
Two 400 hp Liberty 12A liquid-cooled Vee engines. Maximum speed 105 mph at sea level, 100 mph at 6500 feet. 92 mph cruising speed at sea level. Landing speed 53 mph. Service ceiling 10,300 feet. Absolute ceiling 12,250 feet. Initial climb rate 630 feet per minute. An altitude of 6500 feet could be attained in 14 minutes. Range 390 miles with 1040 pound bombload. Empty weight 6702 pounds, gross weight 10,225 pounds. Wingspan 71 feet 5 inches, length 44 feet 10 inches, height 14 feet 7 inches, wing area 1070 square feet. Defensive armament was five 0.30-inch Lewis machine guns. Bombload was normally 1040 pounds.