That’s the story of the Boeing 737.
In the early 1960s, the American aircraft manufacturer Boeing led the development of passenger jets. Its four-engined Boeing 707 was not the first passenger jet airliner, but it turned out to be the first commercially successful one.
Soon development started on a smaller three-engined Boeing 727, primarily designed to service domestic flights in the US. Soon, however, Boeing came under pressure by other aircraft makers who offered even lighter and cheaper jets, capable of operating from smaller airfields. Thus, Boeing began an urgent development programme concentrating on a 100-seater, capable of flying a distance of some 2500 km, or 1553 miles, which would enable it to rapidly gain ground on its rivals.
In order to cut costs, the decision was made to reduce the size of the Boeing 727. Since the new aircraft was to carry around a third less passengers, the body of the Boeing 727 was shortened. The lighter plane rendered the third engine superfluous. The aircraft turned out to be fairly short, something that made placing the engines in the back unsuitable.