Wittemann-Lewis XNBL-1

XNBL-1 "Barling Bomber"
Role	Heavy bomber
Manufacturer	Wittemann-Lewis
Designer	Walter Barling
First flight	22 August 1923
Retired	1928
Primary user	United States Army Air Service
Number built	1
Unit cost	$525,000 ($7.54 million in today's dollars)

The Wittemann-Lewis NBL-1 "Barling Bomber" was an experimental long-range, heavy bomber built for the United States Army Air Service in the early 1920s. Although unsuccessful as a bomber, it was an early attempt at creating a strategic bomber.

Development of the XNBL-1 (Experimental Night Bomber, Long Range) Barling Bomber is generally attributed (the press called it "Mitchell's Folly") to William "Billy" Mitchell, a U.S.Army Air Service General and most vocal advocate of strategic airpower, who in 1919 discovered Walter H. Barling, who had previously worked for the Royal Aircraft Factory. Mitchell asked Barling to design a bomber capable of carrying enough bombs to sink a battleship. Mitchell's goal was to demonstrate the effectiveness of airpower by sinking a battleship from the air, and needed a large, strategic bomber in order to accomplish this feat. Mitchell projected the cost of two prototype bombers at $375,000. On 15 May 1920, the Army Engineering Division sought bids for the construction of a bomber based on Barling's sketches, with the requirement that it be capable of carrying a 5,000 lb (2,300 kg) bomb load, to an altitude of 10,000 ft (3,000 m) at a speed of no less than 100 mph (160 km/h).

Barling had previously designed the Tarrant Tabor, which was similar in concept but was destroyed in a fatal nose-over crash on its first flight in 1919. The nose-over had probably been caused by the high placement of two of the six engines – a compromise due to the lack of more powerful engines. Like the Tabor, the Barling Bomber was a large six-engined triplane with a cigar-shaped fuselage. Unlike its predecessor, the Barling had all of its engines mounted level with the fuselage. The aircraft used three wings, but was not actually a triplane. More correctly, it was a two-and-a-half wing aircraft. The middle wing had no control surfaces, and was shorter and narrower than the two primary wings. The top and bottom wings had a chord of 13 ft 6 in (4.11 m), and each had a surface area of about 2,000 sq ft (190 m²). The stabilizer and elevator surfaces were 575 sq ft (53.4 m²) with an 8 ft (2.4 m) chord. The fins and rudders looked like a box kite, and had a surface area of 250 sq ft (23 m²). The undercarriage consisted of 10 wheels, including two wheels mounted towards the front of the aircraft (to prevent a nose-over on takeoff) and a tail skid.