Mission Analysis and Aircraft Sizing of a Hybrid-Electric Regional Aircraft

The purpose of this study was to explore advanced airframe and propulsion technologies for a small regional transport aircraft concept (approximately 50 passengers), with the goal of creating a conceptual design that delivers significant cost and performance advantages over current aircraft in that class. In turn, this could encourage airlines to open up new markets, reestablish service at smaller airports, and increase mobility and connectivity for all passengers. To meet these study goals, hybrid-electric propulsion was analyzed as the primary enabling technology. The advanced regional aircraft is analyzed with four levels of electrification, 0 percent electric with 100 percent conventional, 25 percent electric with 75 percent conventional, 50 percent electric with 50 percent conventional, and 75 percent electric with 25 percent conventional for comparison purposes. Engine models were developed to represent projected future turboprop engine performance with advanced technology and estimates of the engine weights and flowpath dimensions were developed. A low-order multi-disciplinary optimization (MDO) environment was created that could capture the unique features of parallel hybrid-electric aircraft. It is determined that at the size and range of the advanced turboprop: The battery specific energy must be 750 watt-hours per kilogram or greater for the total energy to be less than for a conventional aircraft. A hybrid vehicle would likely not be economically feasible with a battery specific energy of 500 or 750 watt-hours per kilogram based on the higher gross weight, operating empty weight, and energy costs compared to a conventional turboprop. The battery specific energy would need to reach 1000 watt-hours per kilogram by 2030 to make the electrification of its propulsion an economically feasible option. A shorter range and/or an altered propulsion-airframe integration could provide more favorable results

Energy and Climate Implications for Agricultural Nutrient Use Efficiency

Energy and climate change are beginning to dominate the global political agenda and will drive policy formation that will shape the future of agriculture. Energy issues threaten national security and economic stability, as well as access to low-cost nutrient inputs for agriculture. Climate change has the potential to cause serious disruption to agricultural productivity. Paradoxically, nutrient use in agriculture to increase crop yields has the potential to negatively impact climate. This chapter will discuss recent and future energy and climate trends, the relationships between agricultural nutrient use efficiency and biofuels, and how global land limitations will shape agriculture in the future. Comparative gross energy yield and nitrogen use efficiency for ethanol production from crop residue, switchgrass, grain sorghum, sweet sorghum, and corn grain is presented, showing small differences in nitrogen use efficiency, but large differences in gross energy yields. In addition to considering the need to increase crop productivity to meet the demands of a growing population and bioenergy, agricultural nutrient use efficiency must be reconsidered with respect to the important energy and climate challenges shaping agriculture today

Design, Economic Competitiveness, and Profitability of a 2025 LNG Fueled Turboprop for the LNG Air Transportation System

This paper describes the technical characteristics, lifecycle emissions and economic competitiveness of a hypothetical liquid natural gas (LNG) powered turboprop when introduced into a market place with both existing turboprops and potential competitive responses between 2025 and 2030. Natural gas possesses vast potential to reduce emissions and improve operating costs in commercial aviation because it is cheaper and cleaner than jet fuel. The results show that LNG turboprop can completely robustly against current turboprops (ATR-72 and Bombardier Q400), the competitive responses of stretched derivative of the Q400 to 90 seats, and against discounted used version of current turboprops. Specifically, the LNG turboprop can achieve between a 9% and 15% operating cost advantage compared to current turboprops, 4.9%-8.9% against a stretch of the Q400 turboprop, and, a 3%-11% advantage against existing turboprops sold or leased at steep discounts. The program is shown to be profitable and yield a positive internal rate of return on invested capital between 9% and 17% if market share levels between 47% and 75% are achieved

Design and control for rotor-fixed wing hybrid aircraft

10.1177/2041302510394742Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering2257831-847PMGE