Historical gap in high aspect ratio wing transport aircraft Reading about recent Boeing's high aspect ratio wing concepts for commercial aircraft, such as TTBW and SUGAR, I couldn't help but think of the Hurel-Dubois aircraft, where similar aerodynamic choices seem to have been made back in the 1950s.

Why has there been such a long gap in aircraft history, to see a rebirth of such a high aspect wing ratio transport/commercial aircraft family, since advanced materials to improve the concept were already available in the 1970s?



(TTBW)



(SUGAR)



(Hurel-Dubois 34)



(Hurel-Dubois 10)
High aspect wings provide the best efficiency, but the current airline business model needs more than just efficiency; it also needs to keep speeds up.

Modern airlines could save on fuel by flying slower, but they would lose some business to other forms of transport or airlines that did not slow down as much. As long as fuel prices remain under a certain limit, this trend will continue. In this answer, Peter Kämpf speculates that limit might be around 200USD per barrel (originally gallon, but likely a typo).