Consolidated / Convair
Convair B-36 Peacemaker

The genesis of the B-36 can be traced to early 1941, prior to the entry of the United States into World War II. At the time, the threat existed that Britain might fall to the German "Blitz", making a strategic bombing effort by the United States Army Air Corps (USAAC) against Germany impossible with the aircraft of the time.

The United States would need a new class of bomber that would reach Europe and return to bases in North America, necessitating a combat range of at least 5,700 miles (9,200 km), the length of a Gander, Newfoundland–Berlin round trip. The USAAC therefore sought a bomber of truly intercontinental range, similar to the German Reichsluftfahrtministerium's (RLM) ultralong-range Amerikabomber program, the subject of a 33-page proposal submitted to Reichsmarschall Hermann Göring on 12 May 1942.

The USAAC sent out the initial request on 11 April 1941, asking for a 450 mph (720 km/h) top speed, a 275 mph (443 km/h) cruising speed, a service ceiling of 45,000 ft (14,000 m)—beyond the range of ground-based anti-aircraft fire—and a maximum range of 12,000 miles (19,000 km) at 25,000 ft (7,600 m). These requirements proved too demanding for any short-term design, far exceeding the technology of the day, so on 19 August 1941, they were reduced to a maximum range of 10,000 mi (16,000 km), an effective combat radius of 4,000 mi (6,400 km) with a 10,000 lb (4,500 kg) bombload, a cruising speed between 240 and 300 mph (390 and 480 km/h), and a service ceiling of 40,000 ft (12,000 m)—above the maximum effective altitude of Nazi Germany's anti-aircraft guns, save for the rarely-deployed 12.8 cm FlaK 40 heavy flak cannon.