Aircraft Design Optimization Considering Network Demand and Future Aviation Fuels

Abstract

To reduce the climate impact of aviation, researchers are studying the replacement of fossil kerosene with liquid hydrogen and/or drop-in sustainable aviation fuel (SAF). These fuels can bring significant reductions in CO2 emissions and can offer savings in terms of non-CO2 climate effects. In addition, tube-and-wing aircraft can be optimized to decrease the global-warming impact by using a climate metric as a design objective rather than the operating costs. Previous research has shown that airplanes designed for minimal climate impact have a reduced cruise speed and fly at a lower altitude. This paper suggests a multidisciplinary, multi-level approach the evaluate the consequences of such design and fuels choices at the network level. Following the aircraft design step, a dynamic programming routine allocates the fleet and schedules the flights to maximize the network profit. We consider a hub-and-spoke network operating from Atlanta, with demand for domestic and international destinations. Compared to the reference cost-optimal kerosene fleet, a fleet consisting of climate-optimized kerosene aircraft can reduce the climate impact by 61% at a loss in network profit of approximately 21%. This design choice requires allocating an additional five aircraft. A fleet operating climate-optimal, hydrogen aircraft minimizes the climate impact. However, the high operating cost of long-range, hydrogen aircraft lowers the achievable profit. Aircraft powered by drop-in SAF provides Pareto-optimal solutions. These insights can be used to make decisions about the allocation of future aviation fuels in a network and the payload-range requirements of future aircraft.