The Glenn L. Martin Company produced the first successful twin-engined aeroplane of American design, as the W. F. Night Bomber or "Seven Ton" bomber (first flown on 15 April 1918). As it is generally accepted that the first bomber built for the USAAS was the MB-1, the view can be taken that the W.F. and MB-1 are one and the same. The MB-1 bomber first flown 17 August 1918. Contemporary reports state that the W.F. was converted into the passenger and cargo-carrying Commercial type. Again it is known that one of the ten MB-1 was so converted, although a drawing of the Commercial made in 1921 shows a rounded-nose aircraft with folding outer-wing sections, single-wheel landing-gear units and open cockpit for the pilots, while the MB-1-type Commercial was actually produced with an enclosed cockpit. Nevertheless as features of the Commercial were subsequently to be found on the improved MB-2 bombers, including the revised single- instead of double-wheel landing gear units, it can be taken that the W.F. Commercial and MB-1-type Commercial or T-1 were the same aircraft. All but one of the remaining MB-1 were produced as bombers or observation aircraft, followed by four more military MB-1 for US Government air mail services. A further two were produced as torpedo bombers for the US Navy, which designated them MTB-1.

As an interim stage between the MB-1 and the later MB-2, Martin produced the MT-1 extended-wing torpedo bomber, eight of which were operated by the US Marine Corps. The MB-2 itself was powered by 313kW instead of 298kW Liberty engines and had the wing span of the MT-1 and the landing gear of the Commercial. The NBS-1 was a wood-and-canvas biplane without staggered wings, employing twin rudders on a twin vertical tail.

The first 20 (five MB-2 and 15 NBS-1) were ordered from the Martin Company by the USAAS in June of 1920. In the MB-1, the Liberty engines were suspended between the wings by a system of struts, but on the MB-2, the twin Liberty engines were lowered to sit inside nacelles attached to the lower wing. As compared to the MB-1, the landing gear was simplified to only two wheels. The non-staggered wings were hinged at the rear spars just outboard of the engines, and could be folded aft for storage. The armament consisted of five Lewis 0.50-in machine guns, two in the front cockpit, two in the rear, and one aimed downwards and to the rear. Bombs were carried in racks in a compartment in the fuselage, or, in the case of large bombs, on special racks or chocks directly under the fuselage. A crew of four could be carried. The NBS-1 also had a unique folding-wings system, hinged outside the engine nacelles to fold backwards for storage in small hangars.

The first flight of the MB-2 (serial number AS 64195) took place on September 3, 1920. The MB-2 was designed specifically as a night bomber, and sacrificed the high speed and maneuverability of the MB-1 for a greater bombload. Ten MB-2s were built by the Glenn L. Martin company in Cleveland, and were redesignated NBS-1 when the new Army designation scheme was introduced. Their serials were 64195/64214. These planes are best remembered today as being the aircraft which participated in the famous Billy Mitchell demonstration of aerial bombardment.

The NBS-1 was the primary bomber used by Brigadier General Billy Mitchell during Project B, the demonstration bombing of naval ships in July 1921. Six NBS-1 bombers, led by Captain Walter Lawson of the 96th Squadron operating out of Langley Field, bombed and sank the captured German battleship SMS Ostfriesland on 21 July 1921, using specially-developed 2,000 lb (907 kg) demolition bombs externally mounted beneath the fuselage. Other MB bombers and flying-boats destroyed a submarine, cruiser and destroyer.

 

 

Operators:

United States Army Air Corps
1st Day Bombardment Group, Kelly Field, Texas (2nd Bombardment Group, Langley Field, Virginia)
11th Bomb Squadron - operated MB-2 1920-1927
20th Bomb Squadron - operated NBS-1 1920-1929
49th Bomb Squadron - operated NBS-1 1920-1929
96th Bomb Squadron - operated NBS-1 1920-1928
4th Composite Group, Nichols Field, Luzon, Philippines
28th Bomb Squadron - operated NBS-1 1924-1929
5th Composite Group, Luke Field, Territory of Hawaii
23d Bomb Squadron - operated NBS-1 1922-1929
72d Bomb Squadron - operated NBS-1 1923-1929
6th Composite Group, Albrook Field, Panama Canal Zone
25th Bomb Squadron - operated NBS-1 1922-1929

Martin MB
Engines: 2 x Liberty, 295kW
Max take-off weight: 5477 kg / 12075 lb
Empty weight: 3322 kg / 7324 lb
Wingspan: 21.8 m / 71 ft 6 in
Length: 14.1 m / 46 ft 3 in
Height: 4.3 m / 14 ft 1 in
Wing area: 99.4 sq.m / 1069.93 sq ft
Max. speed: 172 km/h / 107 mph
Range w/max.fuel: 2400 km / 1491 miles
Range w/max.payload: 772 km / 480 miles
Armament: 4-5 machine-guns, 750kg of bombs or torpedos
Crew: 2
Passengers: 12

NBS-1
Engines: 2 x Liberty 12-A, 420 hp (325 kW) each
Length: 42 ft 8 in (13.0 m)
Wingspan: 74 ft 2 in (22.7 m)
Height: 14 ft 8 in (4.8 m)
Wing area: 1,121 sq.ft (104.2 sq.m)
Empty weight: 7,232 lb (3,280 kg)
Loaded weight: 12,027 lb (5,460 kg)
Maximum speed: 99 mph (85 kn, 160 km/h) at sea level
Cruise speed: 92 mph (80 kn, 150 km/h)
Landing speed 59 mph
Range: 400 mi (345 nmi, 650 km) with 2000 lb bomb
Maximum range: 558 miles
Service ceiling: 7,700 ft (2,350 m)
Maximum ceiling: 9900 ft
Rate of climb: 391 ft/min (2.0 m/s)
Armament: 5 x .30 in (7.62 mm) Lewis machine guns
Bombload: 1,800 lb (820 kg) internal; 2,000 lb (907 kg) external
Crew: 4

Martin MB