Northrop N-9M Flying Wing

Northrop/USAAF designations: N-9M-1 / N-9M-2 / N-9MA / N-9MB

Engines: 2 x 290 hp (275 hp/205 kW?) Menasco C6S-4
Engines (N-9M-B): 2 x 400 hp (300 hp?) Franklin OX-540-7

First flight: December 27, 1942

On October 30, 1941, the preliminary order for development of the B-35 flying-wing bomber was confirmed, including engineering, testing, and as extensive engineering work was necessary, development of a 60-foot wingspan 1/3-scale aircraft designated the N-9M was also included, to be used in gathering data on performance. It was hoped that flight data gathered from the N-9M would speed the development of the B-35 project in allowing Northrop to more accurately predict the flight characteristics of the upcoming XB-35, a purpose which presumably would also save money and time. Only one example was ordered in the original contract, but this was expanded to three in early 1943 and a fourth was ordered a few months later. They were designated N-9M-1, -2, -A, and -B, respectively. Their main purpose was to train pilots in handling flying-wing aircraft and to see if the general concept was feasible. As a military variant of the N-1M, the N-9M was similarly built and consisted primarily of a welded steel tube center section and an external covering of wood. As a research model of the XB-35, the 60 foot wing span N-9M closely resembled the future full-size flying wing.

The four N9Ms were later called N-9M-1, N-9M-2, N-9MA, and N-9MB respectively. They were of mixed wood and metal construction to reduce weight, the center section (roughly equivalent to the fuselage) being of welded steel tubing. The covering was of wood and metal panels, with the outer wing panels being of wood with metal wing slots and wing tips. They were initially powered by a pair of 290 hp Menasco C65-4 six-cylinder air-cooled engines each driving a pusher two-bladed propeller by means of an extension shaft via a fluid-drive coupler. The engines were cooled by air admitted by large under-wing scoops. The N9M-B was later fitted with two air-cooled 400 hp Franklin engines. Provisions were made for a pilot and one passenger, both housed underneath a single transparent bubble canopy. It was provided with a retractable tricycle landing gear, and a rear outrigger tail wheel was fitted.

The first N-9M flew for the first time on December 27, 1942, three months behind schedule. It crashed on May 19, 1943 on its 45th flight, after accumulating some 22 hours of flying time, killing its pilot while the other crew members (co-pilot and flight engineer) escaped alive. On the maiden flight of the second model on June 24, 1943, the cockpit canopy of the aircraft flew off while in flight, but the pilot was able to land successfully. Nearly all the flight tests of the N-9M were shortened by mechanical failures of one kind or another, particular with failures in the Menasco engines. The fourth and last N9M (the N-9MB) flew for the first time on September 21, 1943. Flights of these averaged considerably less than one hour each. This time limit was shared by the N-9MB, the fourth N-9, bought to replace the lost N-9M and powered by 2 Franklin 0-540-5 air cooled engines.). Meanwhile, other difficulties had begun to compound the AAF's many problems. All four aircraft flew with neither civil registrations nor military serials.

Hampered by mechanical failings, the N-9M flight test program prevented the acquisition of reliable flight data through 21 September 1943, when the N-9MB, last of the N-9Ms, initially flew. Engines excepted, the N-9MB included all latest design features of the XB-35, but the model's flight testing did not help the XB-35's cause. By the end of November, test results indicated that the XB-35's range would most likely be 1,600 miles shorter than anticipated and that the bomber's highest speed would be at least 24 miles per hour below previous estimates. Such disappointing prognostics were not overlooked. General Arnolde himself began to question the merits of the extensive B-35 production plans.

The design details worked out in the N-9M were incorporated into the design of the XB-35. The N-9MB (the last of the four) managed to survive all these years, and was restored to flying condition over a period of 12 years by volunteers at the Chino 'Planes of Fame Museum' and flew again, for the first time after about 45 years, on November 11, 1994. The new civil registration of the N-9MB is 'N9MB'.

When the B-35 program was cancelled completely, every test model was scrapped, with the exception of the N-9MB. In 1982, volunteers of the Chino Planes of Fame Museum began restoring it to flying condition. On November 11 1994, it flew for the first time in 45 years.

Population: 4 [no military serials, no civil registration]

Specs:
Length: 17 ft 9 in (5.4 m)
Height: 8.5 ft.
Wingspan: 60 ft 0 in (18.3 m)
Wing area: 490.0 sq ft 45.5 sq m
Gross weight: 6,326 lb (2,868 kg)
Loaded weight: 7,000 lb (3,175 kg) (or 7,100 lb.?)

Performance:
Range: 500 miles (805 km)
Cruise Speed: 208 mph (334 km/h, 180 kt)
Max Speed (N-9M-1): 258 mph (415 km/h, 224 kt)
Max Speed (N-9M-B): 320 mph 515 km/h 278 kt
Ceiling (N-9M-1): 19,500 ft (5,943 m)
Service ceiling (N-9M-B): 21,500 ft (6,555 m)

Crew/passengers: 3 (pilot, co-pilot and flight engineer)