The following is an extensive catalogue of the variants and specific unique elements of each variant and/or design stage of the Boeing B-17 Flying Fortress heavy bomber. For a broader article on the history of the B-17, see B-17 Flying Fortress.
The Boeing 299 was the original bomber design made by Boeing to fulfill a request by the United States Army Air Corps

United States Army Air Corps

The United States Army Air Corps was a forerunner of the United States Air Force. Renamed from the Air Service on 2 July 1926, it was part of the United States Army and the predecessor of the United States Army Air Forces , established in 1941...

 for a bomber capable of carrying 2,000 lb (907 kg) of bombs 2,000 mi (3,218 km) at 200 mph (322 km/h).