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This study presents a model to help airlines plan their strategic fleet acquisitions and disposals. It minimizes the discounted costs of owning or leasing and operating a fleet by identifying which aircraft to buy, sell and lease ...
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This study presents a model to help airlines plan their strategic fleet acquisitions and disposals. It minimizes the discounted costs of owning or leasing and operating a fleet by identifying which aircraft to buy, sell and lease over the planning horizon. The paper explains how the related cost data were compiled and analyzed. The model is applied to two US airlines with different business models and shows that aircraft leasing is generally the preferred alternative with benefits from having newer aircraft and less fleet diversity.
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Purpose - To provide an effective design methodology focused on loading structure of unmanned aerial vehicles with a special emphasis on MALE class platform. Design/methodology/approach - Selected design methods and numerical calc...
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Purpose - To provide an effective design methodology focused on loading structure of unmanned aerial vehicles with a special emphasis on MALE class platform. Design/methodology/approach - Selected design methods and numerical calculations used during the development of two different class (MALE PW-103 and HALE PW-114) unmanned aerial vehicles have been described and discussed. The initial loading structure was set-up coming from a steady state level flight condition. Findings - Aeroelastic analysis showed that the wing torsional rigidity is not sufficient. To increase the critical flutter speed the wing sandwich skin has been reinforced adding extra layers of carbon fibres. This procedure is iterative by nature, because adding the new layers changes the weight and stiffness of aircraft and the critical flutter speed has to be computed again. Research limitations/implications - Analysis and design methodology is limited to surveillance and monitoring platforms, where the design objectives are long endurance, high reliability and cost effectiveness of the platform. Practical implications - A very useful source of design information and patterns to follow, especially for engineering students and engineers dealing with unmanned aviation. Originality/value - This paper offers practical help for designers planning an unmanned platform to be well adjusted to the assumed mission, giving a lot of practical information about attachments and fittings, on-board systems integrated with loading structure and integration of composites with metal parts in modern flying platforms.
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The increasing awareness of the environmental risks and costs due to the growing demand in aviation has prompted both academic and industrial research into short-term and long-term technologies which could help address the challen...
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The increasing awareness of the environmental risks and costs due to the growing demand in aviation has prompted both academic and industrial research into short-term and long-term technologies which could help address the challenges. Among these, the more electric aircraft has been identified as a key design concept which would make aircraft more environmentally friendly and cost effective in the long run. Moreover, the notion of free-flight and optimised trajectories has been identified as a key operational concept which would help curb the environmental effects of aircraft as well as reduce overall costs. The research in this paper presents a methodology in which these two concepts can be coupled to study the benefits of more electric aircraft (MEA) flying optimised trajectories. A wide range of issues from aircraft performance, engine performance, airframe systems operation, power off-take penalties, emission modelling, optimisation algorithms and optimisation frameworks has been addressed throughout the study. The case study is based on a popular short haul flight between London Heathrow and Amsterdam Schiphol. The culmination of the study establishes the advantage of the MEA over conventional aircraft and also addresses the enhanced approach to the classical aircraft trajectory optimisation problem. The study shows that the operation procedures to achieve a minimum fuel burn are significantly different for a conventional aircraft and MEA. Trajectory optimisation reduced the fuel burn by 17.4% for the conventional aircraft and 12.2% for the more electric compared to the respective baseline cases. Within the constraints of the study, the minimum fuel burn trajectory for the MEA consumed 9.9% less fuel than the minimum fuel burn trajectory for the conventional aircraft.
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We consider the problem of navigating a military aircraft in a threat environment to its final destination while minimizing the maximum threat level and the length of the aircraft path. The proposed method to construct optimal low...
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We consider the problem of navigating a military aircraft in a threat environment to its final destination while minimizing the maximum threat level and the length of the aircraft path. The proposed method to construct optimal low-risk aircraft paths involves a simple geometric procedure and is very computationally efficient. The effectiveness of the developed algorithm is illustrated by a number of examples and comparisons with a fuzzy logic based algorithm.
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Currently, the importance of aircraft efficiency has increased with the rise in jet fuel prices. Due to high fuel prices and compelling pressures to address environmental concerns, different aircraft concepts have been taken into ...
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Currently, the importance of aircraft efficiency has increased with the rise in jet fuel prices. Due to high fuel prices and compelling pressures to address environmental concerns, different aircraft concepts have been taken into consideration in recent years. These concepts not only include the usage of varied fuel types but also the usage of more electricity. According to the literature on the topic, the most conspicuous alternative fuel type is hydrogen. In this paper, traditional aircraft, more electric aircraft, and liquid hydrogen-fueled aircraft are compared by using a multi criteria scoring method. As a result of this comparison, a future aircraft concept for long distance flights is proposed combining the more electric concept and the liquid hydrogen fueled concept. The suggested future aircraft concept is better than the traditional aircraft with regard to efficiency, cost, and environmental impact. In conclusion, the proposed aircraft concept for long range is an unavoidable choice for the future of the aviation sector to increase energy efficiency and decrease harmful environmental effects. (C) 2017 Elsevier Ltd. All rights reserved.
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The global aircraft industry is expected to develop greatly in the future. Japan has laid out a policy to make the industry a key one following the automobile industry and is trying to grow the industry. Among the aerospace indust...
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The global aircraft industry is expected to develop greatly in the future. Japan has laid out a policy to make the industry a key one following the automobile industry and is trying to grow the industry. Among the aerospace industries that should be grown, the growth of technology for entire aircraft and for aircraft systems (equipment systems) is an urgent issue. Also, there is the big trend of aircraft electrification, which may lead to innovation in aircraft technology. There, it is expected that innovative aeronautical technology will be produced in Japan with the cooperation of the electric/magnetic industry, the material and parts industry, etc., which have not always been closely related to aviation. In this commentary, we will describe the situation of such aircraft technology.
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Purpose - To provide a brief introduction to the special section of papers. Design/methodology/approach - The paper outlines the themes of each of the four papers. Findings - The four invited papers deal with various aspects of op...
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Purpose - To provide a brief introduction to the special section of papers. Design/methodology/approach - The paper outlines the themes of each of the four papers. Findings - The four invited papers deal with various aspects of operational efficiency in aviation. Each paper, either explicitly or implicitly, treats the current concern in the aviation industry with improving this efficiency, although no universally-accepted definition can be found easily in the extensive literature. Originality/value - Introduces the papers which deal with the various aspects of operational efficiency in aviation.
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Purpose-This paper seeks to evaluate the potential of heat exchanged aeroengines for future Unmanned Aerial Vehicle (UAV), helicopter, and aircraft propulsion, with emphasis placed on reduced emissions, lower fuel burn, and less n...
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Purpose-This paper seeks to evaluate the potential of heat exchanged aeroengines for future Unmanned Aerial Vehicle (UAV), helicopter, and aircraft propulsion, with emphasis placed on reduced emissions, lower fuel burn, and less noise.
Design/methodology/approach-Aeroengine performance analyses were carried out covering a wide range of parameters for more complex thermodynamic cycles. This led to the identification of major component features and the establishing of preconceptual aeroengine layout concepts for various types of recuperated and ICR variants.
Findings-Novel aeroengine architectures were identified for heat exchanged turboshaft, turboprop, and turbofan variants covering a wide range of applications. While conceptual in nature, the results of the analyses and design studies generally concluded that heat exchanged engines represent a viable solution to meet demanding defence and commercial aeropropulsion needs in the 2015-2020 timeframe, but they would require extensive development. Research limitations/implications-As highlighted in Parts I and II, early development work was focused on the use of recuperation, but this is only practical with compressor pressure ratios up to about 10. For today's aeroengines with pressure ratios up to about 50, improvement in SFC can only be realised by incorporating intercooling and recuperation. The new aeroengine concepts presented are clearly in an embryonic stage, but these should enable gas turbine and heat exchanger specialists to advance the technology by conducting more in-depth analytical and design studies to establish higher efficiency and 'greener' gas turbine aviation propulsion systems.
Originality/value-It is recognised that meeting future environmental and economic requirements will have a profound effect on aeroengine design and operation, and near-term efforts will be focused on improving conventional simple-cycle engines. This paper has addressed the longer-term potential of heat exchanged aeroengines and has discussed novel design concepts. A deployment strategy, aimed at gaining confidence with emphasis placed on assuring engine reliability, has been suggested, with the initial development and flight worthiness test of a small recuperated turboprop engine for UAVs, followed by a larger recuperated turboshaft engine for a military helicopter, and then advancement to a larger and far more complex ICR turbofan engine.
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The AIEE San Diego Section, host for the Pacific general meeting to be held in San Diego, Calif., August 26–29, 1947, is making the theme of its invitation, “Plan your vacation for the dates of the meeting and stay around as lon...
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The AIEE San Diego Section, host for the Pacific general meeting to be held in San Diego, Calif., August 26–29, 1947, is making the theme of its invitation, “Plan your vacation for the dates of the meeting and stay around as long as you can.” Headquarters for the meeting will be in the San Diego Hotel. An attractive program of entertainment, sports, and trips, with special features for the visiting women, has been arranged. A tentative schedule of events was published in the June issue of ELECTRICAL ENGINEERING (p 596).
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Discussion and author's closure of paper 46–15 by Cyril G. Veinott, presented at the AIEE winter convention, New York, N. Y., January 21–25, 1946, and published in AIEE TRANS-ACTIONS, 1946, February section, pages 84–90.
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