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Nowadays Russia faces a big challenge of restoring the domestic passenger aircraft industry in the shortest possible time. This paper is devoted to the assessment of the potential to develop regional aircraft, which are of great importance not only for our country. The design and operational experience is an important link in the creation of any new aircraft. An extensive retrofit of the basic aircraft model is crucial in this process. The paper considers the conceptual assessment of the existing aircraft retrofit effectiveness, which is specifically related with the transition to composite wings, that provide a capability to increase the aspect ratio due to greater rigidity and reduce the aerodynamic drag, as a consequence. As a rule, the retrofit of out-of-date aircraft models necessarily involves the use of more advanced engines with enhancing performance, including better fuel efficiency. The study was conducted using the sensitivity analysis of takeoff weight to design changes, which has been well established for different types of aircraft. As a specific example, a draft version based on the Yak-40 regional jet is analyzed with a focus on the conducted experimental research carried out SIBNIA in 2012–2019. The results of extensive experimental research obtained by SIBNIA specialists are considered in this paper as a good basis for testing the performance and accuracy of the sensitivity analysis method. The obtained performance in the modified version of Yak-40 in terms of flight range comply well with the results of these practical studies. It is noted that the modified Yak-40 with a flight range of about 4000 km can be successfully operated not only as a regional, but also as a business jet. By its performance, the aircraft under consideration will not be inferior to known aircraft analogues. The paper emphasizes the relevancy to develop a new Russian engine for this aircraft category. In this respect, it is possible to consider a propulsion system with a thrust margin since the excess of internal volume of a passenger cabin can be used to increase the passenger capacity.

A study is performed to comprehensively evaluate the aerodynamic performance of a regional aircraft designed for short-haul flights, with a particular focus on the effects of distributed electric propulsion (DEP) on aerodynamic performances. This effort aligns well with a core objective of the Clean Aviation program to decrease carbon emissions within the aviation sector. To address this challenge, we propose a concept that considers incorporating electric motors to complement the conventional propulsion system of a regional aircraft wing. These electric motors have the capability to draw power from either the traditional turboprop engine or exclusively from an on-board electrical generator, providing an innovative pathway for emissions reduction. The central focus of this study revolves around a detailed examination of the aerodynamic efficacy with respect to the placement of engines within the wing. It seeks to ascertain whether optimal aerodynamic efficiency is achieved through the adoption of a greater number of smaller-diameter motors, characterized by reduced power output to the shaft. Alternatively, the study explores the prospect of employing a reduced number of motors, each possessing larger diameters and correspondingly augmented power output. While a larger motor size may intuitively suggest superiority in terms of thrust, it remains imperative to meticulously evaluate the potential influence of the associated drag factor. This research contributes to the growing body of knowledge in the realm of aviation by shedding light on the intricate interaction between aerodynamic efficiency and power output in the context of propulsion system design.

The adoption of hybrid–electric propulsion, allowing us to partially replace fuel with batteries and to reduce aircraft in-flight emissions, represents one of the main investigated solutions to mitigate the aviation climate impact. Despite its environmental potential being appealing for a practical application, two main drawbacks limit the actual implementation of this technology: first, the low gravimetric energy density of the batteries restricts hybrid–electric aircraft payload and range capabilities; second, the production of electricity is currently not entirely based on renewable energy sources, hence a non-direct emissions budget may limit the benefit in terms of overall decarbonization. When designing hybrid–electric aircraft, even projecting its actual entry into service in the next decades, it is necessary to take these limitations into account depending on both the more reliable technological forecasts on the development of electric components and on the estimates of electricity production. A proper analysis of the figure of merits related to the operation of such an aircraft, therefore, becomes crucial in assessing the impact related to its introduction into service. In this context, trade-offs between different performance metrics may be needed to efficiently exploit the environmental benefits of such an advanced concept, while limiting the possible drawbacks coming from its utilisation. This paper provides a performance analysis of hybrid–electric aircraft through an assessment of the relevant figures of merit characterizing its operations. In particular, direct and non-direct emissions, climate impact, ground pollution, operating costs, fuel consumption, weight, and a combination of these figures of merit allow us to define a proper development perimeter in which a possible (future) hybrid–electric aircraft can express its maximum potential towards all the aspects of its utilisation. The trade-off analyses provided in this paper allow us to identify more effective paths for the actual development of hybrid–electric aircraft, highlighting the impact of the selected design variables on the performance metrics, and bringing to light also the possible related limitations. [ABSTRACT FROM AUTHOR]

The Hybrid Electric Regional Aircraft Distribution Technologies (HECATE) Clean Aviation project will mature and develop breakthrough technologies and perform scalability and impact analysis to ensure safe and power-dense technologies that will enable Entry Into Service (EIS) of hybrid-electric regional aircraft by 2035. Along the project, a circular economy approach in future aircraft will be ensured through the use of Life Cycle Assessment (LCA), performing this type of assessment on the overall electrical system and primary/secondary distribution and conversion technologies, helping to be in line with long-term environmental roadmaps such as Flightpath 2050. This communication includes a description of the HECATE activities and how LCA will be applied to the future Regional Aircraft Electrical Distribution System. [ABSTRACT FROM AUTHOR]

A study is performed to comprehensively evaluate the aerodynamic performance of a regional aircraft designed for short-haul flights, with a particular focus on the effects of distributed electric propulsion (DEP) on aerodynamic performances. This effort aligns well with a core objective of the Clean Aviation program to decrease carbon emissions within the aviation sector. To address this challenge, we propose a concept that considers incorporating electric motors to complement the conventional propulsion system of a regional aircraft wing. These electric motors have the capability to draw power from either the traditional turboprop engine or exclusively from an on-board electrical generator, providing an innovative pathway for emissions reduction. The central focus of this study revolves around a detailed examination of the aerodynamic efficacy with respect to the placement of engines within the wing. It seeks to ascertain whether optimal aerodynamic efficiency is achieved through the adoption of a greater number of smaller-diameter motors, characterized by reduced power output to the shaft. Alternatively, the study explores the prospect of employing a reduced number of motors, each possessing larger diameters and correspondingly augmented power output. While a larger motor size may intuitively suggest superiority in terms of thrust, it remains imperative to meticulously evaluate the potential influence of the associated drag factor. This research contributes to the growing body of knowledge in the realm of aviation by shedding light on the intricate interaction between aerodynamic efficiency and power output in the context of propulsion system design. [ABSTRACT FROM AUTHOR]

Hybrid-Electric Propulsion (HEP) could be part of the solution to decrease emissions associated with regional commercial aviation. This study presents results for the aircraft level fuel reduction potential of a regional turboprop concept with an HEP architecture and Entry-Into-Service (EIS) in 2035+. The configuration specifically tackles the elaborated challenges of introducing an additional electrical energy source to the configuration by employing a twofold electrical assistance to a turboshaft engine in combination with an innovative thermal management concept. Relevant components and disciplines were modeled and incorporated into an integrated aircraft design environment. The behavior and interaction of the HEP architecture with the aircraft was thoroughly investigated. A best-performing configuration was derived and compared with a conventional reference configuration following a State-of-the-Art (SoA) reference aircraft approach. For a typical mission with 200 nmi range, a block fuel reduction of 9.6% was found. However, the assumed battery performance characteristics limited the reduction potential and led to a fuel burn increase for the 600 nmi design mission. Furthermore, sourcing the non-propulsive subsystems directly from the on-board battery was detrimental. The innovative Thermal Management System (TMS) located in the propeller slipstream showed a synergistic effect with the investigated configuration. [ABSTRACT FROM AUTHOR]

This paper presents the design of a 2 MW superconducting electric machine capable of replacing a conventional regional aircraft turbine. The main objective of this work is to advance in the path towards the more-electric aircraft, by incorporating and assessing in the same design technologies such as a superconducting rotor and its cooling by means of helium at cryogenic temperatures, the skewed armature winding or the oil-flooded cooling of the stator, to obtain high specific power density and efficiency values. Although the use of these technologies is well known in the literature, no work is found to implement all of them simultaneously, which poses great challenges both for their subsequent manufacture and later performance. After showing and justifying each element of the design of the electric machine, the electromagnetic performance of the motor and of the superconducting coils is assessed, it is thermally evaluated so that it does not exceed the strict temperature limits and a mechanical analysis of the elements of the motor is also carried out. The main finding of this work is the validation of the proposed model, and that, even though the designed engine is feasible at the proposed power level, the specific power density and efficiency values would improve in the case of upscaling the engine for implementation in larger aircraft.

Life without mobility is inconceivable. To enable this connectivity, one must find a way to progress towards a more sustainable transportation. In the aviation industry, a comprehensive understanding of greening technologies such as electrification of the propulsion system for commercial aircraft is required. A hybrid-electric propulsion concept applied to a regional aircraft is studied in the context of the FutPrInt50 project. To this end, the hybrid-electric propulsive system components are modeled, validated, and evaluated using computational and experimental data presented in the literature. The components are then assembled to construct the three powertrains for the hybrid-electric propulsion systems (Series, Parallel and Turboelectric) and parametric studies are carried out to study the influence of various battery parameters and hybridization factor. The performance results for a simple mission profile are generated. Together with a thermal management system, multi-objective optimization studies for the different architectures are then performed, with the power hybridization factor as the design variable and minimization of total mass and emissions as objective functions. [ABSTRACT FROM AUTHOR]

The adoption of hybrid–electric propulsion, allowing us to partially replace fuel with batteries and to reduce aircraft in-flight emissions, represents one of the main investigated solutions to mitigate the aviation climate impact. Despite its environmental potential being appealing for a practical application, two main drawbacks limit the actual implementation of this technology: first, the low gravimetric energy density of the batteries restricts hybrid–electric aircraft payload and range capabilities; second, the production of electricity is currently not entirely based on renewable energy sources, hence a non-direct emissions budget may limit the benefit in terms of overall decarbonization. When designing hybrid–electric aircraft, even projecting its actual entry into service in the next decades, it is necessary to take these limitations into account depending on both the more reliable technological forecasts on the development of electric components and on the estimates of electricity production. A proper analysis of the figure of merits related to the operation of such an aircraft, therefore, becomes crucial in assessing the impact related to its introduction into service. In this context, trade-offs between different performance metrics may be needed to efficiently exploit the environmental benefits of such an advanced concept, while limiting the possible drawbacks coming from its utilisation. This paper provides a performance analysis of hybrid–electric aircraft through an assessment of the relevant figures of merit characterizing its operations. In particular, direct and non-direct emissions, climate impact, ground pollution, operating costs, fuel consumption, weight, and a combination of these figures of merit allow us to define a proper development perimeter in which a possible (future) hybrid–electric aircraft can express its maximum potential towards all the aspects of its utilisation. The trade-off analyses provided in this paper allow us to identify more effective paths for the actual development of hybrid–electric aircraft, highlighting the impact of the selected design variables on the performance metrics, and bringing to light also the possible related limitations.

Hybrid-electric powertrains are considered a promising technology for mitigating noxious emissions and promoting aviation decarbonization, particularly in regional segments with limited flight energy requirements. However, assessing their potential quantitatively proves challenging owing to system complexity and enlarged dimensions of the design space. Traditional aircraft design methods may not guarantee optimal integration of electrical systems, in particular considering batteries current low technology readiness. Therefore, a multidisciplinary optimization framework has been developed and employed to quantitatively assess the potentials of an ATR42-600 regional aircraft retrofitted with hybrid-electric powertrains. The new framework has been conceived to extend the open-source program OpenConcept available design capability to regional turboprop aircraft retrofitted with different hybrid-electric powertrain and thermal management system architectures. Different discipline modules were improved and adapted to commercial aviation by integrating CS/FAR 25 requirements and airworthiness constraints. Optimization campaigns assessed the performance of both serial-hybrid and parallel-hybrid configurations on reference and short-range missions, considering different future battery technology energy densities. Retrofitted solutions were assessed in terms of fossil fuel consumption and CO 2 emissions per kg of payload and km of range. Significant emission reductions can only be obtained for future battery technologies providing a specific energy of 1500 W h/kg for a reduced payload of 3 t. Parallel-hybrid powertrains offer a more integrated solution for regional retrofitted aircraft. However, when CO 2 emissions are normalized by a variable payload, the advantages of the retrofit are only observed for ranges smaller than 600 NM. Analysis of the optimization results has yielded valuable insights on the optimal battery use, which must be allowed along all the mission including diversion to minimize CO 2 emissions. Hybridization strategies, using battery as booster during the most energetically-demeaning flight phases, such as take-off and climb, are not efficient for retrofitted aircraft, as optimal performance requires a combustion engine redesign. [ABSTRACT FROM AUTHOR]

The Hybrid Electric Regional Aircraft Distribution Technologies (HECATE) Clean Aviation project will mature and develop breakthrough technologies and perform scalability and impact analysis to ensure safe and power-dense technologies that will enable Entry Into Service (EIS) of hybrid-electric regional aircraft by 2035. Along the project, a circular economy approach in future aircraft will be ensured through the use of Life Cycle Assessment (LCA), performing this type of assessment on the overall electrical system and primary/secondary distribution and conversion technologies, helping to be in line with long-term environmental roadmaps such as Flightpath 2050. This communication includes a description of the HECATE activities and how LCA will be applied to the future Regional Aircraft Electrical Distribution System.

Hybrid-Electric Propulsion (HEP) could be part of the solution to decrease emissions associated with regional commercial aviation. This study presents results for the aircraft level fuel reduction potential of a regional turboprop concept with an HEP architecture and Entry-Into-Service (EIS) in 2035+. The configuration specifically tackles the elaborated challenges of introducing an additional electrical energy source to the configuration by employing a twofold electrical assistance to a turboshaft engine in combination with an innovative thermal management concept. Relevant components and disciplines were modeled and incorporated into an integrated aircraft design environment. The behavior and interaction of the HEP architecture with the aircraft was thoroughly investigated. A best-performing configuration was derived and compared with a conventional reference configuration following a State-of-the-Art (SoA) reference aircraft approach. For a typical mission with 200 nmi range, a block fuel reduction of 9.6% was found. However, the assumed battery performance characteristics limited the reduction potential and led to a fuel burn increase for the 600 nmi design mission. Furthermore, sourcing the non-propulsive subsystems directly from the on-board battery was detrimental. The innovative Thermal Management System (TMS) located in the propeller slipstream showed a synergistic effect with the investigated configuration.

During the recent decade a lot of research has been focused on identification of the importance of regional airport for the local economy and the measuring and predicting of the airport’s efficiency. With regard to individual airport planning it turns out that airports are not free in the optimization of infrastructure due the need to comply international aviation standards and recommended practices, one the one hand, and the tendency of air transportation system development including aircraft design and airlines’ fleet development, on the other. Furthermore, it is also important to take into account the specificity of each particular airport, including the traffic variability resulting from seasonality, with the airport’s mission geared to it. We found, tha t one of the reasons for the relatively low efficiency of regional airports, given the general trend in the growth in the number of seats for narrow-body aircraft. Likewise, it has been found, that the seasonality of air traffic at regional airports is comparatively high. In addition, this paper spotlights the ways the theoretical model of returns to scale affects the efficiency of the apron of the regional airport and briefly discusses the different interpretations of the definition of regional airport.

Life without mobility is inconceivable. To enable this connectivity, one must find a way to progress towards a more sustainable transportation. In the aviation industry, a comprehensive understanding of greening technologies such as electrification of the propulsion system for commercial aircraft is required. A hybrid-electric propulsion concept applied to a regional aircraft is studied in the context of the FutPrInt50 project. To this end, the hybrid-electric propulsive system components are modeled, validated, and evaluated using computational and experimental data presented in the literature. The components are then assembled to construct the three powertrains for the hybrid-electric propulsion systems (Series, Parallel and Turboelectric) and parametric studies are carried out to study the influence of various battery parameters and hybridization factor. The performance results for a simple mission profile are generated. Together with a thermal management system, multi-objective optimization studies for the different architectures are then performed, with the power hybridization factor as the design variable and minimization of total mass and emissions as objective functions.

This analysis is dedicated to find out methods for setting of route networks where new aircraft can be effectively put into service. The conception of this analysis is based on the idea of so called connectivity principle for airports connected by passenger traffic with each other.For the passenger traffic analysis the author took passenger traffic data by federal districts starting from the Far East. Then consequently the data for Siberian, Ural, Wolga, Northwestern, Central, Southern and North Caucasian federal districts were analyzed. Passenger traffic to the Crimea was treated separately. Detailed specifications of passenger traffics were provided in order to determine the connections between airports both within federal districts and beyond them and with neighboring areas in western direction. Query of routes was done based on limitations for non-stop flight range and on minimum and maximum (for significant traffics) flight frequencies.The analysis approach lets us concentrate attention on those airlines which at best fit for putting into service of chosen aircraft. Also this method permits to determine the routes with currently insufficient or low traffics but where there’s a definite growth potential. When analysis data are combined with traffic data and tariffs, then it becomes possible to determine the most profitable routes for introduction of new aircraft. Traffic volume, actual figures and forecast, consolidated characteristics of chosen airlines, list of airlines for further studies of efficiency and competitiveness of introduced aircraft are determined.

In the context of reducing the environmental footprint of tomorrow’s aviation, Distributed Electric Propulsion (DEP) has become an increasingly interesting concept. With the strong coupling between disciplines that this technology brings forth, multiple benefits are expected for the overall aircraft design. These interests have been observed not only in the aerodynamic properties of the aircraft but also in the structural design. However, current statistical models used in conceptual design have shown limitations regarding the benefits and challenges coming from these new design trends. As for other methods, they are either not adapted for use in a conceptual design phase or do not cover CS-23 category aircraft. This paper details a semi-analytical methodology compliant with the performance-based certification criteria presented by the European Union Aviation Safety Agency (EASA) to predict the structural mass breakdown of a wing. This makes the method applicable to any aircraft regulated by EASA CS-23. Results have been validated with the conventional twin-engine aircraft Beechcraft 76, the innovative NASA X-57 Maxwell concept using DEP, and the commuter aircraft Beechcraft 1900.

This paper describes a new aircraft concept, where all windows, except those for emergency exits, are replaced with simulated windows, which consist of monitors connected to external cameras to overcome the discomfort for the passenger due to the absence of real windows. This concept is developed through an analytical method to estimate the potential advantages for the environment and for airline companies deriving from a windowless configuration for a short-medium range aircraft, within the boundaries of the preliminary design. Actually, the reduction in weight is directly linked to the reduction in fuel consumption, providing advantages in terms of operating costs and emissions of carbon dioxide. The method is applied to four models of short and medium range aircraft, namely Boeing 737–800, Airbus 320, ATR72 and Embraer 190. The results show the benefits of a windowless configuration that become very positive for the operating life of an aircraft and the total fleet, potentially leading to the saving of millions of tons of carbon dioxide every year when applied to the whole fleet of the analyzed aircraft. [ABSTRACT FROM AUTHOR]

The aviation world is dealing with the development of new and greener aviation. The need for reducing greenhouse gas emission as well as the noise is a critical requirement for the aviation of the future. The aviation world is struggling with it, and a compelling alternative can be the electric propulsion. This work aims to present THEA-CODE, a tool for the conceptual design of hybrid-electric aircraft. The tool evaluates the potential benefits of the electric propulsion in terms of fuel burnt and direct and indirect CO2 emissions. THEA-CODE is suitable not only for conventional “wing-tube” configurations but also for unconventional ones, such as the box-wing. The results show a significant reduction of fuel burnt adopting batteries with energy density higher than the current state of the art. A procedure to find the potential best compromise configurations is presented as well.

An increasing number of aircraft is equipped with wing tip devices, which either are installed by the aircraft manufacturer at the production line or are retrofitted after the delivery of the aircraft to its operator. The installation of wing tip devices has not been a popular choice for regional turboprop aircraft, and the novelty of the current study is to investigate the feasibility of retrofitting the British Aerospace (BAe) Jetstream 31 with an appropriate wing tip device (or winglet) to increase its cruise range performance, taking also into account the aerodynamic and structural impact of the implementation. An aircraft model has been developed, and the simulated optimal winglet design achieved a 2.38% increase of the maximum range by reducing the total drag by 1.19% at a mass penalty of 3.25%, as compared with the baseline aircraft configuration. Other designs were found to be more effective in reducing the total drag, but the structural reinforcement required for their implementation outweighed the achieved performance improvements. Since successful winglet retrofit programs for typical short to medium-range narrow-body aircraft report even more than 3% of block fuel improvements, undertaking the project of installing an optimal winglet design to the BAe Jetstream 31 should also consider a direct operating cost (DOC) assessment on top of the aerodynamic and structural aspects of the retrofit.

This article describes the extent to which hybrid aircraft and all-electric aircraft can present a solution for reducing HC, CO, and NO x emissions and noise in the vicinity of airports, in the category of regional passenger aircraft. The goal of the article is to identify, basing on aircraft technical characteristics and market demands, in which sectors of air transport can all-electric or hybrid aircraft be most feasibly introduced. Firstly, a simple theoretical model based on a connection between the aircraft mass and aircraft energy consumption is used to calculate basic technical characteristics and limitations of hybrid and all-electric aircraft. Second, market demands for regional aircraft are presented and discussed, with the intention of recognising the possibilities of replacing conventional aircraft with all-electric and hybrid aircraft models in regional air transport in the near future. Third, quantity of HC, CO, and NO x, CO gas emissions of regional aircraft in Europe was calculated to recognise the possible reduction of gas emissions if hybrid and all-electric aircraft would be implemented.

Modern transport aircraft wings have reached near-peak levels of energy-efficiency and there is still margin for further relevant improvements. A promising strategy for improving aircraft efficiency is to change the shape of the aircraft wing in flight in order to maximize its aerodynamic performance under all operative conditions. In the present work, this has been developed in the framework of the Clean Sky 2 (REG-IADP) European research project, where the authors focused on the design of a multifunctional twistable trailing-edge for a Natural Laminar Flow (NLF) wing. A multifunctional wing trailing-edge is used to improve aircraft performance during climb and off-design cruise conditions in response to variations in speed, altitude and other flight parameters. The investigation domain of the novel full-scale device covers 5.15 m along the wing span and the 10% of the local wing chord. Concerning the wing trailing-edge, the preliminary structural and kinematic design process of the actuation system is completely addressed: three rotary brushless motors (placed in root, central and tip sections) are required to activate the inner mechanisms enabling different trailing-edge morphing modes. The structural layout of the thin-walled closed-section composite trailing-edge represents a promising concept, meeting both the conflicting requirements of load-carrying capability and shape adaptivity. Actuation system performances and aeroelastic deformations, considering both operative aerodynamic and limit load conditions, prove the potential of the proposed structural concept to be energy efficient and lightweight for real aircraft implementation. Finally, the performance assessment of the outer natural laminar flow (NLF) wing retrofitted with the multifunctional trailing-edge is performed by high-fidelity aerodynamic analyses. For such an NLF wing, this device can improve airplane aerodynamic efficiency during high speed climb conditions.

• Methodologies for preliminary co-design of hybrid regional aircraft electric components and control strategies. • Energy benefits and mass and volumetric impacts of regional aircraft fuel cell hybridization. • Real mission profiles exploited to derive the blended control strategy for the electrified turboprop section. • High-potential of hydrogen and PEM fuel cell technology to mitigate the mass impact of aircraft electrification. • Exploitation of versatile control rules to support the preliminary design of hybrid aircrafts. The growing demand for air travel in the commercial sector leads to an increase in global emissions, whose mitigation entails transitioning from the current fossil-fuel based generation of aircrafts to a cleaner one within a short timeframe. The use of hydrogen and fuel cells has the potential to reach zero emissions in the aerospace sector, provided that required innovation and research efforts are substantially accomplished. Development programs, investments and new regulations are needed for this technology to be safe and economical. In this context, it makes sense to develop a model-based preliminary design methodology for a hybrid regional aircraft assisted by a battery hybridized fuel cell powertrain. The technological assumptions underlying the study refer to both current and expected data for 2035. The major contribution of the proposed methodology is to provide a mathematical tool that considers the interactions between the choice of components in terms of installed power and energy management. This simultaneous study is done because of the availability of versatile control maps. The tool was then deployed to define current and future technological scenarios for fuel cell, battery and hydrogen storage systems, by quickly adapting control strategies to different sizing criteria and technical specifications. In this way, it is possible to facilitate the estimation of the impact of different sizing criteria and technological features, at the aircraft level, on the onboard electrical system, the management of in-flight power, the propulsion methods, the impact of the masses on consumption and operational characteristics in a typical flight mission. The proposed combination of advanced sizing and energy management strategies allowed meeting mass and volume constraints with state-of-the-art PEM fuel cell and Li-ion battery specifications. Such a solution corresponds to a high degree of hybridization between the fuel cell system and battery pack (i.e., 300 kW and 750 kWh), whereas projected 2035 specs were demonstrated to help reduce mass and volume by 23 % and 40 %, respectively. [ABSTRACT FROM AUTHOR]

Ambitious targets to reduce emissions caused by aviation in the light of an expected ongoing rise of the air transport demand in the future drive the research of propulsion systems with lower CO2 emissions. Regional hybrid electric aircraft (HEA) powered by conventional gas turbines and battery powered electric motors are investigated to test hybrid propulsion operation strategies. Especially the role of the battery within environmentally friendly concepts with significantly reduced carbon footprint is analyzed. Thus, a new simulation approach for HEA is introduced. The main findings underline the importance of choosing the right power-to-energy-ratio of a battery according to the flight mission. The gravimetric energy and power density of the electric storages determine the technologically feasibility of hybrid concepts. Cost competitive HEA configurations are found, but do not promise the targeted CO2 emission savings, when the well-to-wheel system is regarded with its actual costs. Sensitivity studies are used to determine external levers that favor the profitability of HEA.

The study is aimed at investigating the feasibility of a high TRL solution for a wing flap segment characterized by morphable camber airfoil and properly tailored to be implemented on a real-scale regional transportation aircraft. On the base of specific aerodynamic requirements in terms of target airfoil shapes and related external loads, the structural layout of the device was preliminarily defined. Advanced FE analyses were then carried out in order to properly size the load-carrying structure and the embedded actuation system. A full scale limited span prototype was finally manufactured and tested to: demonstrate the morphing capability of the conceived structural layout; demonstrate the capability of the morphing structure to withstand static loads representative of the limit aerodynamic pressures expected in service; characterize the dynamic behavior of the morphing structure through the identification of the most significant nonnal modes. Obtained results showed high correlation levels with respect to numerical expectations thus proving the compliance of the device with the design requirements as well as the goodness of modeling approaches implemented during the design phase. [ABSTRACT FROM AUTHOR]

Abstract: To develop approaches that effectively reduce engine environmental effect of aircrafts, it is necessary to understand the mechanisms that have enabled improvements in thermodynamic efficiency of aircraft engines. In the present work, a turboprop engine used in regional aircrafts that produces 1948 shp and 640 N.m torque is examined using exergo-environmental method. The results show compressor, combustion chamber, gas generator turbine, power turbine and exhaust nozzle create 9%, 69%, 13%, 7%, 2% of total environmental impact of the engine, respectively. According to rates, the compressor and gas turbine can be considered first to improve in case of component related environmental impact. Furthermore, total component related environmental impact for the turboprop engine is found to be 2.26 mPts/s for the constructional phase and 2.34 mPts/s for the operation/maintenance phases. Accordingly, it is suggested that, in order to estimate environmental impact metric of aircrafts, the exergo-environmental analysis can be employed for aircraft propulsion systems. [Copyright &y& Elsevier]

Abstract: Light weight design of fuselage structures is a major goal for future aircrafts to reduce structural weight for increased efficiency regarding fuel consumption. One objective is to validate and demonstrate the technology that offer the best opportunities of weight reduction and short production time. It involves the development of laser welding technologies for difficult weldable high strength aluminum alloys, containing Cu and / or Li. Another objective is to identify and evaluate approaches for first welding trials on T-joints of the alloy 2139 which are very promising regarding weld seam quality and achieved mechanical properties. [Copyright &y& Elsevier]

In the context of reducing the environmental footprint of tomorrow's aviation, Distributed Electric Propulsion (DEP) has become an increasingly interesting concept. With the strong coupling between disciplines that this technology brings forth, multiple benefits are expected for the overall aircraft design. These interests have been observed not only in the aerodynamic properties of the aircraft but also in the structural design. However, current statistical models used in conceptual design have shown limitations regarding the benefits and challenges coming from these new design trends. As for other methods, they are either not adapted for use in a conceptual design phase or do not cover CS-23 category aircraft. This paper details a semi-analytical methodology compliant with the performance-based certification criteria presented by the European Union Aviation Safety Agency (EASA) to predict the structural mass breakdown of a wing. This makes the method applicable to any aircraft regulated by EASA CS-23. Results have been validated with the conventional twin-engine aircraft Beechcraft 76, the innovative NASA X-57 Maxwell concept using DEP, and the commuter aircraft Beechcraft 1900. [ABSTRACT FROM AUTHOR]

To develop approaches that effectively reduce aircraft emissions, it is necessary to understand the mechanisms that have enabled historical improvements in aircraft efficiency. This paper focuses on the impact of regional aircraft on the US aviation system and examines the technological, operational and cost characteristics of turboprop (TP) and regional jet (RJ) aircraft. Regional aircraft are 40–60% less fuel efficient than their larger narrow- and wide-body counterparts, while RJs are 10–60% less fuel efficient than TPs. Fuel efficiency differences can be explained largely by differences in aircraft operations, not technology. Direct operating costs per revenue passenger kilometer are 2.5–6 times higher for regional aircraft because they operate at lower load factors and perform fewer miles over which to spread fixed costs. Further, despite incurring higher fuel costs, RJs are shown to have operating costs similar to TPs when flown over comparable stage lengths. [Copyright &y& Elsevier]