The first American-built large bomber flown by the U.S. Navy and Marine Corps was the Glenn Martin GMB-1, as the Army designated the aircraft.1 The U.S. air services flew mostly European-built aircraft in combat during World War I. Thus, in January 1918 the U.S. Army awarded a contract to the newly established Martin aircraft company to design and build ten twin-engine reconnaissance bombers to replace the British Handley-Page and the Italian Caproni bombers then flown by the Army.
The chief designer of the GMB-1 was Donald Douglas, who would become one of the world’s leading aircraft designers of the World War II era. The Army’s first aircraft flew on 15 August 1918. Its success led the Navy to order ten of the bombers a year later, in September 1919. Two of the latter were duplicates of the GMB-1 for Navy service (designated MBT) and eight improved variants for the Marine Corps (MT).2
After flying the first Navy MBT on its third flight, Navy Lieutenant Commander N. B. Chase sent a telegram to the Bureau of Construction and Repair: “The plane functioned beautifully and no sign of any adjustments being needed in any part of the plane was observed.”3 Aviation historian Major John M. Elliott noted, “They were an easy aircraft to fly and when properly trimmed could be flown ‘hands off’ for extended periods.”4
The MBT/MT was a large twin-engine aircraft that was relatively graceful for its era. A biplane, its outer wings folded back for easier ground handling and stowage. Initially the engines were mounted between the wings (in the Army’s GMB-1s and the Navy’s MBTs). Subsequently, they were moved to a position on the lower wings (in the Marine MTs), with the later aircraft having longer wings.
The large, boxy fuselage originally had open cockpit positions for a crew of three: pilot and observer seated side-by-side, and a rear gunner. Later a radio compartment was fitted within the fuselage with a radio operator added to the crew. And the aircraft could also carry internal cargo or a few (cramped) passengers or troops. Initially one .30-caliber Lewis machine gun was fitted on a Scarff ring in the tail of the aircraft. Additional Scarff-ring guns could be fitted. Distinctive features of the aircraft included the four-wheel main undercarriage and two vertical tail fins.
Interestingly, there was no direct access through the fuselage to the rear gunner’s position. According to Major Elliott: “It was expected that the rear gunner would remain there during flight to protect the rear. However, a walkway was provided on top of the fuselage for access to the rear cockpit and the Martin Co. felt it could be used in flight if necessary.”5
The payload for the Navy aircraft was one Mark VII torpedo of approximately 1,700 pounds or bombs up to a total weight of 2,100 pounds. The bombs were to be carried under the fuselage (in place of a torpedo) and under the wings. The specifications were changed for the MT aircraft—seven of the aircraft were to carry a Mark VII torpedo or a 1,000- or 1,650-pound bomb under the fuselage, but only two 230-pound bombs under the wings. The design of the eighth Marine aircraft was modified with three bays that could accommodate 18 112-pound bombs. In the event, the eighth Marine MT was configured the same as the first seven with respect to weapons carriage.
The major problem with the aircraft was propellers. The original cherrywood props as well as many replacement ones cracked. Another issue was water in aircraft fuel at the time, with separation devices taking time—and aircraft crashes—to rectify.
As indicated by their designations, the aircraft were envisioned primarily as carrying antiship torpedoes. In April 1920 a Navy MBT carried out torpedo-release trials in the Anacostia River in Washington, D.C.—within sight of the U.S. Capitol. Torpedo trials also were conducted at Yorktown, Virginia.
Four of the MT aircraft were crated and shipped to the San Diego naval air station in 1920 for use by the Pacific Fleet Air Detachment. Designated T-1 through T-4 upon arrival and reassembly, these aircraft appear to have constituted the Pacific Fleet’s aerial torpedo unit. In 1921 the two MBTs and three MTs were assigned to the Atlantic Fleet Torpedo Plane Division—later squadron VT-1B—and in March 1921 they began bombing practice. Their targets were the surrendered German battleship Ostfriesland and light cruiser Frankfurt, and the radio-controlled U.S. battleship Iowa (BB-1).6 Significantly, although the MBT/MTs were designed as torpedo planes, they used aerial bombs and not torpedoes against the target ships. (Army aviation proponent Brigadier General William “Billy” Mitchell would use improved MB-2s to sink the Ostfriesland in the controversial bombing exercise of July 1921.)
Subsequently, three of the MT aircraft were held at Hampton Roads, Virginia, for transfer to the Navy’s first aircraft carrier, the Langley (CV-1). But while the aircraft did not go aboard the Langley, it is possible that landings and takeoffs were made from the simulated carrier deck located at Norfolk.
Both the MBTs and MTs were flown by Navy and Marine pilots and units, with both of the former as well as the MTs being transferred to Marine aviation at Quantico, Virginia, in 1921. Four of the MTs (the T-planes) were flown from San Diego to Quantico, the longest flight made by the aircraft—with numerous stops en route. Despite several mechanical difficulties and weather problems, the four aircraft completed the flight two days ahead of schedule.
Although Marine employment of the Martin bombers was relatively brief, experiments were conducted in dropping paratroopers from the aircraft. One MT was fitted with additional radios for six operators and used as a flying classroom. Another was used in 1927 to simulate a German Gotha bomber in the film Now We’re in the Air with Wallace Beery.
Finally, outdated and too expensive to maintain, the Navy-Marine Martin bombers were retired in 1928, from Marine Observation Squadron 8. The Army had already retired its GMB-1s. The Army had modified several of its GMB-1s: One mounted a 37-mm cannon, one had a third engine mounted in the nose, and a ten-passenger model was flown. Another was fitted with additional fuel tanks to provide a range of 1,500 miles. The GMB-1s also flew as mail carriers when the Army took over U.S. air-mail service. Only ten GMB-1s were built for the Army, being succeeded by the larger MB-2 aircraft.
Thus, the Douglas-designed, Martin-built reconnaissance bomber had a key role in bringing large, land-based bomber aviation to the U.S. Navy and Marine Corps.
The author appreciates the assistance of James Caiella in preparing this column.
1. The aircraft generally was referred to as the MB-1; the official Army designation was GMB-1 for Glenn Martin Bomber No. 1.
2. The most comprehensive published account of the Navy–Marine Corps variants is the excellent article by Major John M. Elliott, U.S. Marine Corps (Retired), “The Martin MBT/MT Story,” American Aviation Historical Society Journal (Summer 1967), 144–59. See also Gordon Swanborough and Peter M. Bowers, U.S. Military Aircraft since 1909 (Washington, DC: Smithonian Institution Press, 1989), 429–30.
3. Elliott, 147.
4. Ibid., 144.
5. Ibid., 145.
6. The Iowa was launched in 1896 and retired in 1919 after seeing action in the Spanish-American War and being employed as a training ship in World War I.
Glenn Martin MT
Type: Reconnaissance torpedo bomber
Crew: 3 to 5, plus passengers
Gross weight: 12,098 pounds
Length: 45 feet, 8 inches
Wingspan: 71 feet, 5 inches
Wing area: 1,080 square feet
Height: 15 feet, 8 inches
Engines: 2 Liberty, 400 horsepower each
Max. speed: 109 mph
Ceiling: 10,000+ feet
Armament: Guns, torpedoes, bombs