The requirement that produced the B-36 was written in April 1941, before the United States had even entered the war. The fear was concrete: if Britain fell, the U.S. would lose every forward base within striking distance of Germany, and any bomber launched from North America would need intercontinental legs. The Army Air Forces asked for a machine that could carry 10,000 lb of bombs to a target 5,000 miles away and return — a 10,000-mile round trip with no refuelling, at a time when the best heavy bombers could barely manage a fraction of that.

Development was deliberately slowed once the B-29 proved able to reach Japan from Pacific island bases, and the giant Convair design was not urgently needed during the war. It was the arrival of the atomic bomb and the Cold War that gave it a mission: an aircraft that could put a nuclear weapon on Moscow from Texas. The B-36 was, in a sense, a weapon designed for one war and pressed into service for another.

Each R-4360 Wasp Major packed 28 cylinders in four rows and produced around 3,800 horsepower — the most powerful piston aero-engine ever to reach mass production. On the B-36 they were mounted as pushers, buried in the thick wing with the propellers on the trailing edge, which kept the wing aerodynamically clean but left the engines prone to cooling problems and even in-flight fires. Engine fires were a recurring hazard; one of them triggered the type’s first major loss in 1950. The later addition of four J47 jets gave the aircraft a burst of speed for the bomb run and shortened its take-off, producing the celebrated “six turning, four burning” configuration.

With a wingspan of about 70 metres and a length near 49 metres, the B-36 remains the largest mass-produced piston-engined aircraft ever built and had the longest wingspan of any combat aircraft in history. Its wing area of roughly 443 square metres dwarfed contemporaries; parked next to a B-29 — itself a huge bomber — the Peacemaker looked from another scale entirely. The nickname “aluminum overcast” captured the sight of one passing overhead. Yet it was subsonic and, by the mid-1950s, increasingly vulnerable to jet fighters — which is why its reign was measured in a single decade.

The B-36 was among the most expensive aircraft programmes of its era. Contemporary figures put the flyaway unit cost at very roughly $4.1 million in early-1950s dollars — a substantial sum, though sources vary and it should be read as an order-of-magnitude estimate rather than a precise, audited number. Maintaining ten engines, six of them enormous 28-cylinder radials that were notoriously hard to keep running, made the type maintenance-heavy; but a firm, sourced cost-per-flight-hour figure for the B-36 does not exist in the open record. Any exact modern dollar figure attached to it is an estimate. Programme totals across the roughly 384 airframes built ran into the billions.