Northrop N-9M

The Northrop N-9M was an approximately one-third scale, 60-foot (18 m) span flying wing aircraft used for the development of the full size, 172-foot (52 m) wingspan Northrop XB-35 and YB-35 flying wing long-range, heavy bomber. First flown in 1942, the N-9M (M for Model) was the third in a lineage of all-wing Northrop aircraft designs that began in 1929 when Jack Northrop succeeded in early experiments with his single pusher propeller, twin-tailed, twin-boom, all stressed metal skin Northrop X-216H monoplane, and a decade later, the dual-propeller N-1M of 1939–1941. Northrop's pioneering all-wing aircraft would lead Northrop Grumman many years later to eventually develop the advanced B-2 Spirit stealth bomber, which debuted in 1989 in US Air Force inventory.

Design and development

On 30 October 1941, the preliminary order for development of the B-35 Flying Wing bomber was confirmed, including engineering, testing, and most importantly a 60 ft (18 m) wingspan, one-third scale aircraft, designated N-9M. It was to be used in gathering data on flight performance and for familiarizing pilots with the program's radical, all-wing design. The first N-9M was ordered in the original contract, but this was later expanded to three test aircraft in early 1943. A fourth was ordered a few months later after a crash of the first N-9M destroyed that airframe; this fourth N-9M incorporated various flight test-derived improvements and upgrades, including different, more powerful engines. The four aircraft were designated N-9M-1, -2, A, and B, respectively.

The N-9M framework was partially constructed of wood to reduce its overall weight. The wings' outer surfaces were also skinned with a strong, specially laminated plywood. The central section (roughly equivalent to the fuselage) was made of welded tubular steel.