Assessment of the BWB aircraft for military transport

Purpose The growth in air mobility, rising fuel prices and ambitious targets in emission reduction are some of the driving factors behind research towards more efficient aircraft. The purpose of this paper is to assess the application of a blended wing body (BWB) aircraft configuration with turbo-electric distributed propulsion in the military sector and to highlight the potential benefits that could be achieved for long-range and heavy payload applications. Design/methodology/approach Mission performance has been simulated using a point-mass approach and an engine performance code (TURBOMATCH) for the propulsion system. Payload-range charts were created to compare the performance of a BWB aircraft with various different fuels against the existing Boeing 777-200LR as a baseline. Findings When using kerosene, an increase in payload of 42 per cent was achieved but the use of liquefied natural gas enabled a 50 per cent payload increase over a design range of 7,500 NM. When liquid hydrogen (LH2) is used, the range may be limited to about 3,000 NM by the volume available for this low-density fuel, but the payload at this range could be increased by 137 per cent to 127,000 kg. Originality/value The results presented to estimate the extent to which the efficiency of military operations could be improved by making fewer trips to transport high-density and irregular cargo items and indicate how well the proposed alternatives would compare with present military aircraft. There are no existing NATO aircraft with such extended payload and range capacities. This paper, therefore, explores the potential of BWB aircraft with turbo-electric distributed propulsion as effective military transports

Structural Batteries for Aeronautic Applications—State of the Art, Research Gaps and Technology Development Needs

Radical innovations for all aircraft systems and subsystems are needed for realizing future carbon-neutral aircraft, with hybrid-electric aircraft due to be delivered after 2035, initially in the regional aircraft segment of the industry. Electrical energy storage is one key element here, demanding safe, energy-dense, lightweight technologies. Combining load-bearing with energy storage capabilities to create multifunctional structural batteries is a promising way to minimize the detrimental impact of battery weight on the aircraft. However, despite the various concepts developed in recent years, their viability has been demonstrated mostly at the material or coupon level, leaving many open questions concerning their applicability to structural elements of a relevant size for implementation into the airframe. This review aims at providing an overview of recent approaches for structural batteries, assessing their multifunctional performance, and identifying gaps in technology development toward their introduction for commercial aeronautic applications. The main areas where substantial progress needs to be achieved are materials, for better energy storage capabilities; structural integration and aircraft design, for optimizing the mechanical-electrical performance and lifetime; aeronautically compatible manufacturing techniques; and the testing and monitoring of multifunctional structures. Finally, structural batteries will introduce novel aspects to the certification framework

Modelling geared turbofan and open rotor engine performance for year-2050 long-range and short-range aircraft

The paper provides design and performance data for two envisaged year-2050 engines: a geared high bypass turbofan for intercontinental missions and a contra-rotating pusher open rotor targeting short to medium range aircraft. It defines component performance and cycle parameters, general arrangements, sizes and weights. Reduced thrust requirements reflect expected improvements in engine and airframe technologies. Advanced simulation platforms have been developed to model the engines and details of individual components. The engines are optimised and compared with 'baseline' year-2000 turbofans and an anticipated year-2025 open rotor to quantify the relative fuel-burn benefits. A preliminary scaling with year-2050 'reference' engines, highlights trade-offs between reduced specific fuel consumption (SFC) and increased engine weight and diameter. These parameters are converted into mission fuel burn variations using linear and non-linear trade factors. The final turbofan has an optimised design-point bypass ratio of 16.8, and a maximum overall pressure ratio of 75.4, for a 31.5% TOC thrust reduction and a 46% mission fuel burn reduction per passenger kilometre compared to the respective 'baseline' engine-aircraft combination. The open rotor SFC is 9.5% less than the year-2025 open rotor and 39% less than the year-2000 turbofan, while the TOC thrust increases by 8% versus the 2025 open rotor, due to assumed increase in passenger capacity. Combined with airframe improvements, the final open rotor-powered aircraft has a 59% fuel-burn reduction per passenger kilometre relative to its baseline

Design and Integration of a Hybrid Electric Fan Propulsion System

Poster presented at the Cranfield Doctoral Network Annual Event, September 2018.Design and Integration of an Electric Fan Propulsion System for Hybrid Aircraft Electrification is one of the most promising trend for sustaining future aviation beyond the limits of current propulsion technologies. Advantages include lower emissions, higher efficiency components, better energy management and synergies with alternative technologies. Current limits are in higher costs, inferior power density and shorter ranges. Hybrid electric propulsion looks for synergies between current state-of-the-art engines and novel electric motors/batteries, the latter considered as black boxes.The research project aims to investigate quantitatively the unexplored design space for an electric fan propulsion system fitted on a specifically-designed nacelle for regional aircraft. The study entails with the assessments of the overall arrangement and geometry design, evaluating effects of internal pressure losses and cooling air requirements. A viable solution for the organization of the internal volume is the installation of a variable area nozzle. Its adoption would optimise fan performance along a defined mission, allowing a consistent reduction in power and size of electrical components, estimated up to 15%.Additional objectives are the assessment of critical integration aspects of the hybrid technology, such as trade-offs between size and weight of units, degree of hybridization, strategies for efficient energy usage. A techno-economic assessment would top the project, defining viability and economic feasibility of the technology. A realistic evaluation of the uncertainties associated will be included as it is essential to provide solid background to any result.The research uses a combination of dedicated performance software and mainly relies on CFD calculations for the investigation of the internal flows.The project is relevant in the context of evolving aerospace industry, as major companies are consistently investing in electric aviation. It provides contribution to existing knowledge and foundation for future research in the field, both at academic and industrial level