Experience with the N-1M convinced Northrop that an all-wing bomber was feasible, and following evaluation by USAAF engineers a design contract was awarded under the designation XB-35. Four 18.29m span N-9M scale models were built to provide flight data but the first, flown in December 1942, was lost in a fatal crash early the following year. The first three N-9Ms had two 205kW Menasco air-cooled engines, but the fourth, the N-9MB, had 224kW Franklins; all drove pusher propellers. A three-year test programme was flown from Muroc Army Air Base, providing much data and giving pilots experience in the handling and performance of flying wings, and the autopilot for the XB-35 was developed in an N-9M. All N-9Ms had retractable landing gear and varying colour schemes; the first two were all yellow, the third (N-9MA) was blue on top and yellow underneath, while the fourth (N-9MB) had the colour reversed. The colours identified the top or bottom of the aircraft during observations of the flight programme.

3-View

A three-view drawing (752 x 240)