1934 Y1B-17 - Army Air Corps purchases it's first strategic bombers

AN AMERICAN BOMBER IS BORN
In 1934, the U.S. Army Air Service announced a multiengine bomber competition. Boeing answered with the company-funded XB-17, which added two engines to its YB-9 design that allowed the Model 299 to surpass the Army’s requirements. Pilot error caused the Model 299 to crash and Boeing to lose the competition, but Army leadership believed in the plane’s abilities and ordered 13 Y1B-17s. The aircraft, a predecessor for the B-17, could fly 256 miles per hour at 30,600 feet with a range of 3,320 miles-well past the competition’s desired 200 miles per hour at 10,000 feet for 10 hours.

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This is a mix of footage of different airplanes from different times. The first 25 seconds or so are of Boeing's twin-engined YB-9 design of 1931 (in the early part, it's the Y1B-9 version with liquid-cooled engines). The next part, starting at