The world’s first commercial jet aircraft, the de Havilland Comet, took its first flight in 1949, marking the beginning of the jet age for air travel. Today, over 4.5 billion passengers annually enjoy fast, convenient and relatively affordable travel in the 25000 aircraft flying in the global commercial fleet. This number is projected to increase by 4.3% each year . Due to the concerning growth of global carbon dioxide emissions, air travel has come under scrutiny for having some of the highest CO2 emissions per passenger-kilometre (or per ton-kilometre for cargo) among all forms of transportation, at 285 g per passenger-km. Nevertheless, it is naïve to assume that the human population will ever forgo the luxury of flight, so the focus shifts instead to reducing the relative emissions by increasing the efficiency of aircraft.