The Curtiss-Martin NBS-1 was a twin engined biplane bomber of the early 1920s that was designed by Glenn Martin but produced by Curtiss, Aeromarine and L.W.F.
Martin designed the MB-2 in response to a US Army request for a bomber aircraft to replace the wartime de Havilland designs then in use. The MB-2 design was tested against a number of rivals, and was found to have the best performance.
During the 1920s there was never any guarantee that the company that originally designed an aircraft would receive the production order. The US Army purchased the manufacturing rights along with the prototype of any new aircraft, and then allowed other companies to bid to produce it. This allowed companies that hadn't had to pay any of the development costs to underbid the original company. In the worst cases the original company went bankrupt while their design was being built elsewhere, not a good way to build up an industry capable of producing good new designs.
In the case of the NBS-1 Martin had produced the first twenty aircraft, as the Martin MB-2. In 1921 the Army decided to buy another 110 MB-2s, with the new NBS-1 designation (Night Bomber Short Range number 1). The order was split between three companies, with Curtiss producing 50, Aeromarine of Keyport 25 and L.W.F. of College Point the final 35. This attempt to support smaller companies wasn't a great success - both Aeromarine and L.W.F. shut down after building their NBS-1s (Aeromarine was reopened in 1929).
The MB-2/ NBS-1 was a conventional aircraft of the early 1920s. It had a wooden framework for both the fuselage and wings, and was entirely fabric covered. The only unusual feature was the main undercarriage - in most aircraft of the period the main wheels were connected in some way, while on the NBS-1 the main wheels, with each one mounted under one of the two engines.
The NBS-1 was a three bay biplane with equal chord equal length wings. The engines were mounted above the lower wing in the innermost bay. Unusually for a land aircraft the wings folded back from a point just outside the engines. This was done in order to make it easier to handle the aircraft's 74ft 2in wingspan.
The first thirty Curtiss NBS-1s used the standard Liberty engine. The last twenty were given General Electric turbo-supercharges, the first time that device was installed in a production aircraft. Six of these turbo-supercharged NBS-1s were used in Mitchell's famous tests of the value of airpower against surface ships on 5 September 1923, when aircraft sank the surplus warships USS Virginia and USS New Jersey.
The NBS-1 had a fairly short service career, with the last ones being withdraw in 1928, only six years after production ended. During that short period it took part in a number of early experiments in air power. In October 1924 the 2nd Bombardment Group used nine NBS-1s on a night flight from Langley Field to Mitchel Field, New York. Seven arrived on time, one an hour late and one on the following day, demonstrating that sizable formations of aircraft could be moved around the country quite quickly. This meant that the US Army wouldn't need to position aircraft at every vulnerable point, but instead could concentrate its aircraft and move them to any danger spot quickly. The NBS-1 was also used in the 1926 air force manoeuvres.
The NBS-1 was one of the first US Army aircraft to carry radios as standard equipment.
The NBS-1 also took part in some more unusual missions. In March 1924 of NBS-1s and DH-4Bs bombed an ice floe on the Platte River, saving a number of bridges from being damaged or destroyed.
Curtiss was given a contract to produce one improved all-metal version of the NBS-1, which emerged as the XNBS-4. This was only produced in prototype form, but entered production in a modified form as the Curtiss B-2 Condor.
Engine: Two Liberty engines
Power: 420hp each
Span: 74ft 2in
Length: 42ft 7.75in
Height: 14ft 8in
Empty weight: 7,268lb
Gross weight: 12,064l
Max speed: 98.7mph
Climb Rate: 193ft/ min
Service ceiling: 8,500ft
Range: 550 miles
Armament: Five .30in machine guns
Bomb load: 1,334lb