Design Drivers of Energy-Efficient Transport Aircraft

The fuel energy consumption of subsonic air transportation is examined. The focus is on identification and quantification of fundamental engineering design tradeoffs which drive the design of subsonic tube and wing transport aircraft. The sensitivities of energy efficiency to recent and forecast technology developments are also examined. Background and Motivation Early development of the modern jet transport, starting with the DeHavilland Comet and Boeing 707 in the 1950’s, was strongly driven by range requirements. With the imperatives of rising fuel costs and increased environmental concerns, more recent developments have focused on fuel economy and also on noise. Of the three main drivers of fuel economy — aerodynamics, structures, and propulsion — the latter has seen the largest improvements, not surprisingly because in the 1950’s turbojet and turbofan engines were a very young technology. As engine technology maturation has now reached the levels of the other disciplines, further improvements will have to come from all technologies. The recent and ongoing NASA Aeronautics research, 1 in particular the N+1,2,3 programs 2 target a wide range of aerodynamic, structural, and propulsion technologies towards this goal.