The N-9M Series

The first, the N-9 M-1, was first flown on the December 27, 1942. It was supposed to have a range of 3.2 hours, carrying 100 gallons of fuel up to 21,500 feet and weighing 7,000 pounds. The first N-9M was powered by two Menasco C6S-4 engines, which proved to be a source of considerable trouble.

The N-9 M-1 made about 45 flights, most of which were terminated by failures in the engines or other systems. On May 19, 1943, after only 22 hours of flight time, the N-9 M-1 crashed near Muroc Army Air Base. The pilot was killed after the plane was in a spin, and was unable to exit the plane.

The second plane, the N-9 M-2, first flew on June 24, 1943. This flight was terminated when the canopy came off in flight! Fortunately, the pilot was able to land the plane with only minor damage. The N-9 M-2 generated a large amount of data on drag, which led to the conclusion that the wind tunnel data for the planned XB-35 was incorrect, and the plane would have roughly 10% greater drag than planned.

One of the more interesting things discovered during flight tests was the severe reversal of elevator control forces at high lift coefficients. This was caused by premature separation of the airflow over the top of the wing, and may have been a contributing factor to the loss of the first N-9M.

The N-9MA was first flown on June 28, 1944. This version featured the controls which would be built on the XB-35, which included split trailing edges, pitch control flaps, and a leading edge slot near the wing tips. These features improved the rough air handling of the design, as the first N-9Ms were reported as being unsatisfactory in that regard.

The N-9MB featured more powerful 300 hp Franklin engines, and, like the N-9M-1, featured a passenger seat behind the pilot.

One of the N-9Ms is currently owned (and flown!) by the Planes of Fame Museum, in Chino, California.