Boeing’s early jet-bomber studies — the Models 424 and 432 — kept the straight wings of the piston era and performed poorly. The decisive input came in 1945, when George Schairer, serving on General Hap Arnold’s scientific mission in occupied Germany, examined German high-speed aerodynamic research showing that a swept wing delays compressibility drag as an aircraft nears the speed of sound. Schairer’s letter back to Seattle prompted Boeing to abandon the straight-wing layout. Engineer Vic Ganzer worked out an optimum sweep of about 35 degrees, and after the Air Force rejected fuselage-buried engines as a fire risk, the team hung six engines in underwing pods. The resulting Model 450 was so far ahead of its rivals that it effectively defined the shape of the jet age — a shape Boeing reused on the B-52 and the 707.

The same thin, flexible wing that made the B-47 fast also made it fragile. The wingtips could move through roughly 17 feet of total deflection between full up-bending and down-bending — and the constant flexing, worsened by punishing low-level manoeuvres, fatigued the metal where the wing met the fuselage. In 1957–58 the fleet suffered a wave of fatal in-flight break-ups. The Air Force responded with a major structural-reinforcement effort (nicknamed “Project Milk Bottle”) plus temporary groundings and speed restrictions. It was a hard lesson in metal fatigue that fed directly into later jet design.

The clean swept wing that made the B-47 fast also made it hard to slow down. Crews used two parachutes. On final approach a small approach chute was streamed so the engines could be kept at high RPM — ready to spool up instantly for a go-around — without the aircraft accelerating. On the runway a large brake chute was deployed to haul the fast, heavy bomber to a stop in a reasonable distance. The techniques, like so much of the B-47, were later refined on Boeing’s jet airliners.

A B-47E is commonly cited at a flyaway cost of about $1.9 million in early-1950s dollars — a useful order-of-magnitude figure, though period accounting mixed airframe, engine and equipment costs in ways that make any single number approximate. No credible cost-per-flight-hour figure for 1950s Strategic Air Command operations exists in the open record, so any precise dollar-per-hour value attached to the type should be treated as an estimate rather than a sourced fact. What is certain is that the programme was vast: with more than 2,000 aircraft and a fleet flying constant alert, the B-47 was one of the most expensive military undertakings of its decade.