After the loss of the Model 299, the Boeing Aircraft Co. was dropped from the Army Air Corps competition for a new bomber; however, the cause of the Model 299 crash was determined to be pilot error -- the pilot took off with the elevator lock still engaged. The Army leadership was convinced the aircraft had the potential to fill the long-range bomber requirement and ordered 13 service test aircraft (Boeing Model 299B) as Y1B-17 in 1936. The Y1 (instead of Y) indicates a funding source outside of the normal fiscal year procurement. The designation changed to YB-17 on Nov. 20, 1936, before the first aircraft flew.
The Second Bomb Group based at Langley Field, Va., took delivery of the first YB-17 on March 1, 1937. General Andrews (Commander of the Army's General Head Quarters Air Force) wanted heavy bomber techniques developed as quickly as possible so all but one of the 13 YB-17s ordered were assigned to the 2nd Bomb Group. The 13th YB-17 was the only aircraft actually used for extensive flight testing. It was assigned to the Material Division at Wright Field, Ohio.
Service test aircraft
Armament: Five .30-cal. (or .50-cal.) machine guns and 8,000 lbs. of bombs
Engines: Four Wright R-1820-39 Cyclone radials of 930 hp each
Maximum speed: 256 mph at 14,000 ft.
Cruising speed: 175 mph
Service ceiling: 30,600 ft.
Range: 3,320 miles
Span: 103 ft. 9 in.
Length: 68 ft. 9 in.
Height: 15 ft. 0 in.
Weight: 34,873 lbs. gross
Serial number: 36-149 to 36-161