Boeing B-17 Flying Fortress Y1B-17

After the original order was cut from 65 to 13 aircraft, the designation changed to Y1B-17 once funding moved outside the normal annual budget line. It replaced the prototype's Pratt & Whitney R-1690 with the Wright R-1820 Cyclone, which became the standard engine for the rest of the family, and crew size dropped from seven to six. Twelve aircraft went to the 2nd Bombardment Group at Langley Field to develop heavy-bombing tactics, with the thirteenth used for structural testing. In May 1938 aircraft from this batch intercepted the Italian liner Rex far out at sea to demonstrate the bomber's range, prompting the Navy to demand the Army stay within a hundred miles of the coast.