Search

The Ultra-High Aspect Ratio Wing (UHARW) concept can improve the aircraft's aerodynamic efficiency and reduce fuel consumption. The Twin-Fuselage (TF) configuration is one of the promising concepts for the UHARW design to reduce the wing bending moments and shear forces. This paper presents the development of a semi-empirical method for the weight estimation of TF aircraft in the initial sizing stage. A physics-based wing weight estimation method is improved for higher fidelity aerodynamic analysis and modified for composite material structures of TF aircraft. This method is used in the design of experiments and the results are applied for regression analysis to establish a semi-empirical method. Eventually, the established semi-empirical weight estimation method is integrated into a TF aircraft conceptual design and performance analysis framework. A mid-range TF aircraft and a long-range TF aircraft are designed and sized to illustrate its application and efficiency in rapidly estimating the TF aircraft weight breakdown. [ABSTRACT FROM AUTHOR]

Ease of maintenance can significantly contribute to reducing aircraft operational cost. Maintenance risk is defined as the opposite of maintenance ease; it is impacted by many factors, most of which are decided upon during the aircraft's conceptual design. This paper proposes a novel method to assess the maintainability risks of aircraft systems by combining various aspects on the component level, intercomponent level, bay level, and aircraft level. For each level, all contributing factors to maintenance risk are analyzed and integrated into several scores. These maintenance risk scores can be used to assess the various aspects contributing to maintenance risk, using input parameters available during the conceptual design phase. This paper presents the validation of the scores using different components and aircraft equipment bays, such as avionic racks, the nose cone, and a complex aft equipment bay of a business jet. The proposed maintenance risk scoring method will enhance multidisciplinary tradeoff studies during aircraft conceptual design, considering competing design aspects such as system placement, thermal aspects, impact on aircraft balancing, or even the overall aircraft shape. Therefore, this new conceptual design capability enables designing novel aircraft configurations featuring unconventional system component placement or component bay shapes while considering maintenance aspects upfront. [ABSTRACT FROM AUTHOR]

This paper presents an overall performance assessment of hybrid-electric medium-range transport aircraft, with the aim to evaluate the potential of such a propulsion technology towards the reduction in the environmental impact of aviation transport, in terms of both local air quality degradation in airport areas and climate change. The proposed approach presents distinct analyses of the environmental impact of transport aircraft, distinguishing climate-changing effects from local pollution effects so that the integration of hybrid-electric propulsion is carried out to face the two issues specifically. The proposed analysis, although of conceptual nature, presents a clear scenario in which, given the technological limitations of batteries, the use of hybrid-electric propulsion on medium-haul aircraft can only be useful to reduce local pollution. In contrast, other solutions are needed to mitigate the climate-changing impact. [ABSTRACT FROM AUTHOR]

This paper reports the first part of a series of studies related to conceptual design of a fixed-wing UAV for Mars exploration. For a UAV intended for a single flight mission during the day, rational design parameters were determined and flight performance was estimated. [ABSTRACT FROM AUTHOR]

This paper presents an assessment of the potential fuel burn savings offered by the transonic strut-braced-wing configuration within the single-aisle class of aircraft relative to a modern conventional tube-and-wing aircraft through aerodynamic shape optimization based on the Reynolds-averaged Navier-Stokes equations. A representative strut-braced-wing aircraft is first developed through conceptual multidisciplinary design optimization based on the Airbus A320neo, with current technology levels assumed. A concept for the conventional tube-and-wing configuration is also developed to represent the Airbus A320neo as a performance baseline. Single-point aerodynamic shape optimization is then performed on wing-body-tail models of each aircraft to address aerodynamic design challenges and to provide more accurate performance estimates. Results indicate that shock formation can be mitigated from the wing-strut junction of the strut-braced wing at Mach 0.78 and a relatively high design lift coefficient of 0.750, providing an 8.2% reduction in block fuel over a 1000 n mile nominal mission when compared to the conventional tube-and-wing aircraft. Multipoint aerodynamic shape optimization is then performed to build toward a more credible estimate of fuel burn performance, with results showing a reduction in the fuel burn savings to 7.8% at the nominal design point relative to the conventional tube-and-wing aircraft to maintain a 7.6-8.0% improvement over the envelope of operating conditions, which includes design points at even higher Mach numbers and lift coefficients. These results demonstrate the viability of the transonic strut-braced-wing configuration for transport aircraft within the single-aisle class and its potential for reducing commercial fleet fuel burn. [ABSTRACT FROM AUTHOR]

In response to escalating environmental concerns and stringent economic constraints, there is an urgent need to develop aircraft technologies and configurations that substantially enhance efficiency. A prominent trend in aircraft design aimed at minimizing lift-induced drag, improving fuel efficiency, and mitigating emissions is the adoption of increased wing Aspect Ratio (AR). This paper examines the evolution and current advancements in High Aspect Ratio Wing (HARW) and Ultra-High Aspect Ratio Wing (UHARW) configurations for next-generation transport aircraft. Beginning with a historical overview of wing AR in transport, the paper examines the progress in designing both conventional and novel HARW/UHARW configurations. It reviews a range of promising concepts, such as strut-braced wing, truss-braced wing, twin-fuselage, and folding wingtips, for their potential in HARW applications. The paper emphasizes tailored conceptual design methods and tools specifically developed for HARW/UHARW configurations. It provides an in-depth analysis of preliminary design approaches for HARW aircraft, systematically covering aspects including aerodynamic, aeroelastic, aerostructural, and experimental designs. Key insights from leading-edge research are distilled, highlighting the significant advancements and pinpointing the current challenges in the field. The comprehensive review underscores the critical role of HARW/UHARW in enhancing aircraft performance, particularly in fuel efficiency and environmental impact, setting the stage for future transformative developments in aircraft efficiency. [ABSTRACT FROM AUTHOR]

The conceptual design optimization of wide-body commercial aircraft is very challenging today. This paper deals with the conceptual design optimization problem of a next-cycle wide-body commercial aircraft, which has many similarities to the one being co-developed by China and Russia. The most difficult weaknesses are that the design requirements cannot be traded off during the conceptual design optimization process. To overcome this issue, a competitiveness model is built up for the wide-body commercial aircraft. The analytic hierarchy process is applied to formulate the competitiveness model, which is a multi-level evaluation model. The competiveness model includes three levels, i.e. target level, criteria level, and attributes level. The target level has an output, i.e. the competitiveness of the investigated aircraft, which serves as the single objective function in the conceptual design optimization problem. The criteria level includes four elements of economics, comfort, environmental impact, and adaptability. In addition, each criterion is further divided into more attributes, which are parameters obtained from the commercial aircraft conceptual design. By using the competitiveness model, the conceptual design optimization problem is converted into an unconstrained one that can be solved easily. Two optimizations with different judgment matrices for criteria level were performed. Compared with the baseline design candidate, the overall competitiveness of the optimal design for the optimization case 1 and case 2 increased by 9.28% and 11.51%, respectively, which benefits the designers and decision-makers. [ABSTRACT FROM AUTHOR]

Aircraft manufacturers often consider producing multiple derivatives of aircraft to satisfy various market demands and technical changes while keeping development costs and time to a minimum. Many approaches have been proposed for carrying out derivative design. However, these approaches consider both the baseline design and derivatives together at the conceptual design stage using the entire set of design variables with an assumed set of expected requirements. These frozen requirements on derivative design cannot consider new demands from market changes. In this paper, a method is proposed that uses design optimisation for conceptual design of derivatives for existing aircraft that consider requirement changes. Furthermore, the Possibility-Based Design Optimisation (PBDO) method was implemented to consider uncertainty in the aircraft operation phase. The altitude range of aircraft operation was defined as an uncertain parameter to prevent violation of constraints in the entire operating envelope of the aircraft. The PBDO method yields a more conservative design than those obtained with deterministic design optimisation.In this paper, the proposed derivative design process was applied to the Expedition 350, a small piston engine powered aircraft produced by Found Aircraft, Canada. A derivative that changes the normally aspirated engine to a turbocharged engine for high-altitude operation was considered. An optimum configuration with the new engine was obtained while enhancing performance and stability characteristics. The proposed derivative design process can be implemented on the derivative design of other aircraft. [ABSTRACT FROM PUBLISHER]

This paper demonstrates design of a commercial aircraft at the conceptual design stage by considering 2 objective functions i.e. minimization of aircraft maximum takeoff weight and maximization of lift-to-drag ratio multi-objective evolutionary algorithms (MOEAs). Dynamic stability is taken as a design constraint while design variables include geometrical properties of the plane, consisting of the wing, empennage and fuselage. The aerodynamic coefficients of flight were calculated by using SUAVE (Aerospace Conceptual Design Environment) whereas dynamic stability analysis was achieved through using Athena vortex lattice (AVL) software. Pareto front obtained from various MOEAs are compared by Hypervolume. MOEAs are contained as MOEA / D, Two-Arch2, RPBILDE, PICEA-g, KnEA/A-ENS and KnEA. The obtained solutions for aircraft can be used for further design in the preliminary design stage. [ABSTRACT FROM AUTHOR]

Reducing greenhouse gas emissions has become a priority for civil transport aviation. One of the possible solutions investigated by current aeronautics research is the introduction of electric propulsion, which would drastically reduce greenhouse gas emissions related to flight. This paper addresses this topic in depth; the work is structured in two intertwined parts. The first relates to an extensive review of the state of the art, starting with the analysis of electrical technology enablers for aviation applications, and leading to the investigation of current proposals of aircraft conceptual designs, both for short-medium range and regional class. This review section, which is presented with a critical approach, provides the relevant indications for the definition of the technical framework of the second part of the paper, in which the conceptual development of a novel hybrid-electric aircraft is proposed. Specifically, the outcomes from the analysis of the state of the art suggest that the hybrid-electric aircraft should belong to the regional category, and that energy efficient solutions for the airframe should be considered. Moreover, potentials and limitations of integrating hybrid-electric propulsion are carefully detailed, and reasonably realistic technology levels for the next decade have been selected for the design of the proposed aircraft. A box-wing airframe architecture has been adopted as it has the potential to minimize induced aerodynamic drag while increasing the load transport capacity, thus representing an aerodynamic efficient solution. A design and optimization framework has been developed to evaluate the integration of the hybrid-electric propulsion with the box-wing lifting system. The coupling of these two technologies, together with a paradigm change in the aircraft design approach, allow to identify conceptual solutions that minimize fuel consumption throughout the typical regional mission envelope, leading to a potential emission-free regional aircraft. • Hybrid-electric propulsion is proposed as solution to reduce aircraft emissions. • Electric components technology forecast is widely analysed. • State of the art of hybrid-electric aircraft concepts is discussed. • Novel regional box-wing hybrid-electric aircraft is introduced. • Multidisciplinary design optimization to minimize fuel consumption is proposed. [ABSTRACT FROM AUTHOR]

This paper presents a framework to support decision-making in aircraft conceptual design optimisation under uncertainty. Emphasis is given to graphical visualisation methods capable of providing holistic yet intuitive relationships between design, objectives, feasibility and uncertainty spaces. Two concepts are introduced to allow interactive exploration of the effects of (1) target probability of constraint satisfaction (price of feasibility robustness) and (2) uncertainty reduction through increased state-of-knowledge (cost of uncertainty) on design and objective spaces. These processes are tailored to handle multi-objective optimisation problems and leverage visualisation techniques for dynamic inter-space mapping. An information reuse strategy is presented to enable obtaining multiple robust Pareto sets at an affordable computational cost. A case study demonstrates how the presented framework addresses some of the challenges and opportunities regarding the adoption of Uncertainty-based Multidisciplinary Design Optimisation (UMDO) in the aerospace industry, such as design margins policy, systematic and conscious definition of target robustness and uncertainty reduction experiments selection and prioritisation. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this study of which this work is only the first part, is the development of conceptual design tools to perform an optimized design of the rear fuselage and tail surfaces. The development of a new and extensive database of transport aircraft and an analysis of certain general, rear fuselage and horizontal stabilizer parameters of the aircraft are presented in this paper. Design/methodology/approach – In addition to the development of a comprehensive high accurate database, linear and non-linear correlations between different parameters of the aircraft have been established. Data were analyzed using comparison criteria between aircraft database based on the mission, the number of engines installed or arrangement of the tail surfaces. Findings – It has been possible to obtain very relevant, linear and non-linear correlations for critical design parameters to optimize the design of the rear fuselage and horizontal tail. Research limitations/implications – In the case of the tail cone, the data have not yielded significant correlations. On the other hand, there are some regressions that do not work well in some cases and for which it would be good to further expand the database. Practical implications – Results obtained greatly improve the existing methods for conceptual design, which usually pay no attention to the rear part of the aircraft. Besides, these new procedures are adapted to different categories of aircraft, allowing greater optimization of the designs. Originality/value – The novel contribution of this work is focused on the development of a new high-fidelity database and includes many more aircraft than any other work previously released. Also, new correlations, linear and non-linear, additional parameters not considered in previous studies, and differentiated by category of aircraft studies are provided. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study the consideration of uncertainty from analysis modules for aircraft conceptual design by implementing uncertainty-based design optimization methods. Reliability-Based Design Optimization (RBDO), Possibility-Based Design Optimization (PBDO) and Robust Design Optimization (RDO) methods were developed to handle uncertainties of design optimization. The RBDO method is found suitable for uncertain parameters when sufficient information is available. On the other hand, the PBDO method is proposed when uncertain parameters have insufficient information. The RDO method can apply to both cases. The RBDO, PBDO and RDO methods were considered with the Multidisciplinary Design Optimization (MDO) method to generate conservative design results when low fidelity analysis tools are used. Design/methodology/approach – Methods combining MDO with RBDO, PBDO and RDO were developed and have been applied to a numerical analysis and an aircraft conceptual design. This research evaluates and compares the characteristics of each method in both cases. Findings – The RBDO result can be improved when the amount of data concerning uncertain parameters is increased. Conversely, increasing information regarding uncertain parameters does not improve the PBDO result. The PBDO provides a conservative result when less information about uncertain parameters is available. Research limitations/implications – The formulation of RDO is more complex than other methods. If the uncertainty information is increased in aircraft conceptual design case, the accuracy of RBDO will be enhanced. Practical implications – This research increases the probability of a feasible design when it considers the uncertainty. This result gives more practical optimization results on a conceptual design level for fabrication. Originality/value – It is RBDO, PBDO and RDO methods combined with MDO that satisfy the target probability when the uncertainties of low fidelity analysis models are considered. [ABSTRACT FROM AUTHOR]

Purpose -- The purpose of this paper is to present a formulation that couples equivalent plate and beam models for aircraft structures analysis, suitable in conceptual design in which fast model generation and efficient analysis capability are required. Design/methodology/approach -- Assembling the complete model with common techniques such as Lagrange multipliers or penalty function method would require a solver capable of handling the combined set of linear equation. The alternative approach proposed here is based on a static reduction of the beam model at specified connection points and the subsequent "embedding" into the equivalent plate model using a coordinate transformation, translating physical dfs in Ritz coordinates, i.e. polynomial coefficients. Displacements and forces on beam elements are recovered with the inverse transformation once the solution is computed. Findings -- An aeroelastic trim analysis on a Transonic CRuiser (TCR) civil aircraft conceptual model validates the hybrid model: as the TCR features a slender flexible fuselage and a wide root chord wing, the capability to reduce the beam model for the fuselage at more than one connection point improved aeroelastic corrections to steady longitudinal aerodynamic derivatives. Originality/value -- Although the equivalent model proposed is simpler than others found in literature, it offers automatic mesh generation capabilities, and it is fully integrated into an aeroelastic framework. The hybrid model represents an enhancement allowing both dynamical and static analyses. [ABSTRACT FROM AUTHOR]

This paper presents an aircraft conceptual design technique with more than three objective functions, called many-objective optimisation. The selection of aircraft configuration is usually achieved using a system engineering approach. This selection approach has the design variables assigned to remove the configuration decision-making process. The design problem is demonstrated for the conceptual design of a fixed-wing unmanned aerial vehicle. Eight objective functions, including power required, take-off weight, take-off distance, landing distance, endurance, range, lift coefficient at cruise and drag coefficient at cruise, are posed, while the constraints are aircraft stability, performance required and take-off distance. Design variables simultaneously determine an aircraft configuration, shape and sizing parameters. Hence a new, many-objective metaheuristic is developed to increase the design performance. A grid-based many-objective metaheuristic with iterative parameter distribution estimation (MM-IPDE-Gr) is developed. It is an enhanced variant of the MM-IPDE with improved reproduction schemes, adaptive parameters and a grid-based clustering technique. Several additional reproduction schemes in mutation and crossover processes with two additional adaptive parameters are integrated to increase population diversity and improve the exploration ability of the algorithm. In addition, the grid-based method is integrated as a clustering technique to improve the Pareto clustering process in many-objective optimisation. The proposed method, with established newly invented metaheuristics, is used to solve the new design problem and its performance compared with existing design methods. It is shown that the proposed many-objective metaheuristic gives the best results. [ABSTRACT FROM AUTHOR]

Structural mass optimisation of an aircraft design is important in increasing the likelihood that a high quality airframe is designed of minimal weight whilst providing necessary resistance to load. Analysis of such structures is often performed at a single level of model fidelity, the selection of which can lead to either excessive computational time or reduced accuracy of results. Alternatively, variable-fidelity modelling may be employed to reduce such computational expense whilst maintaining accuracy, traditionally performed using predetermined levels of fidelity for specific periods of the optimisation process. This paper investigates dynamically controlled variable-fidelity modelling during aircraft conceptual design optimisation wherein fidelity is controlled as a dynamic parameter of the optimisation process. Consequently, model fidelity is adapted during optimisation to promote early discovery of promising design characteristics prior to detailed analysis of the best designs available. Models are constructed through the grouping of similar structural members within elements, thus reducing the number of degrees of freedom and subsequent computational effort required for analysis of each design. A case study is performed to verify the results of analysis and obtain benchmark results for optimisation with static model fidelity prior to the investigation of various set-ups of dynamically controlled variable-fidelity modelling. The results of this study indicate improved design quality using dynamically controlled variable-fidelity modelling compared to using static model fidelity whilst reducing the necessary computation time. [ABSTRACT FROM AUTHOR]

The conceptual design of an aircraft is a challenging problem in which optimization can be of great importance to the quality of design generated. Mass optimization of the structural design of an aircraft aims to produce an airframe of minimal mass whilst maintaining satisfactory strength under various loading conditions due to flight and ground manoeuvres. Hyper-heuristic optimization is an evolving field of research wherein the optimization process is continuously adapted in order to provide greater improvements in the quality of the solution generated. The relative infancy of hyper-heuristic optimization has resulted in limited application within the field of aerospace design. This paper describes a framework for the mass optimization of the structural layout of an aircraft at the conceptual level of design employing a novel hyper-heuristic approach. This hyper-heuristic approach encourages solution space exploration, thus reducing the likelihood of premature convergence, and improves the feasibility of and convergence upon the best solution found. A case study is presented to illustrate the effects of hyper-heuristics on the problem for a large commercial aircraft. Resulting solutions were generated of considerably lighter mass than the baseline aircraft. A further improvement in solution quality was found with the use of the hyper-heuristics compared to that obtained without, albeit with a penalty on computation time. [ABSTRACT FROM AUTHOR]

One of the most critical regulatory issues related to supersonic flight arises from limitations imposed by community noise acceptability. The most efficient way to ensure that future supersonic aircraft will meet low-noise requirements is the verification of noise emissions from the early stages of the design process. Therefore, this paper suggests guidelines for the Landing and Take-Off (LTO) noise assessment of future civil supersonic aircraft in conceptual design. The supersonic aircraft noise model is based on the semi-empirical equations employed in the early versions of the Aircraft NOise Prediction Program (ANOPP) developed by NASA, whereas sound attenuation due to atmospheric absorption has been considered in accordance with SAE ARP 866 B. The simulation of the trajectory leads to the prediction of the aircraft noise level on ground in terms of several acoustic metrics (LAmax, SEL, PNLTM and EPNL). Therefore, a dedicated validation has been performed, selecting the only available supersonic aircraft of the Aircraft Noise and Performance database (ANP), that is, the Concorde, through the matching with Noise Power Distance (NPD) curves for LAmax and SEL, obtaining a maximum prediction error of ±2.19%. At least, an application to departure and approach procedures is reported to verify the first noise estimations with current noise requirements defined by ICAO at the three certification measurement points (sideline, flyover, approach) and to draw preliminary considerations for future low-noise supersonic aircraft design. [ABSTRACT FROM AUTHOR]

Abstract: Design knowledge and experience are the basis to carry out aircraft conceptual design tasks due to the high complexity and integration of the works involved in this phase. Aircraft designers need a computer-aided design package to help them easily carry out conceptual design tasks with their individual strategies. This paper presents a set of web-based aircraft design software framework called Aircraft Design Pad (ADP). The architecture of this web-based software is open so that users can wrap add-on extensions and make their own aircraft conceptual design system. Design and development aspects of ADP are discussed in this paper and a design case is presented to demonstrate its usability and effectiveness. [Copyright &y& Elsevier]

erospace design often involves computationally expensive physics based analysis methods such as Computational Fluid Dynamics (CFD) or the Finite Element Method (FEM). Since conceptual design optimization can require many function evaluations, simplified analysis methods are typically used. Designs optimized with simplified analysis methods may be found to violate design goals when subjected to the high fidelity approaches later in the design process. This paper presents how the uncertainty introduced by an approximation model in the conceptual design of the wing box of a generic light jet can be assessed and managed by applying Reliability Based Design Optimization (RBDO) in order to ensure that a feasible solution is obtained. Additionally, the performance of several alternative RBDO approaches are benchmarked using the wing box conceptual design problem. [ABSTRACT FROM AUTHOR]

A new proposal for formulating reliability-based design optimization problems, named the multistage reliability-based design optimization approach, is presented. The classical reliability-based design optimization formulation determines all decision variables here and now in the presence of uncertainty. Nevertheless, in many complex systems design applications, the product development process gradually evolves through time, and decisions at the ensuing milestones are made on the basis of increased knowledge on previously uncertain factors. If the delay leading to such informed resolutions is deemed acceptable to the decision maker, then it would be advantageous to wait and see how the less-urgent design issues run their courses until more concrete insights on the relevant uncertain parameters are obtained. The multistage reliability-based design optimization approach accounts for such follow-on corrective decisions based on the partial realizations of random parameters at selected stages along the engineering design process, thereby further enhancing the practicality of reliability-based design optimization. This paper presents a mathematical formulation of multistage reliability-based design optimization and its application to a conceptual design of a regenerative solar powered high-altitude aircraft, which indicate that the multistage reliability-based design optimization method, reflecting real-world engineering practices, produces more favorable solutions than the classical reliability-based design optimization approach. [ABSTRACT FROM AUTHOR]

Unconventional aircraft designs, such as nonplanar wings, are being considered for the next generation of transport aircraft. In order to determine the suitability of such designs, conceptual design tools are needed which are both sensitive to these unconventional configurations and capable of obtaining results rapidly. Wings represent a large contribution to an aircraft's empty weight and there are many commonly used conceptual design tools which can accurately estimate this component's weight for conventional designs. However, nonplanar wings can have very different aerodynamic loadings and structural details so existing models cannot be easily extended to treat these complexities. This paper shows the development of a conceptual-level wing weight model which combines a fully-stressed cross-section method with an equivalent beam finite-element structural solver using loads derived from a nonplanar vortex-lattice method. This model is able to obtain accurate aerodynamic loadings for nonplanar wings and can model the statically indeterminate structure of closed wing configurations. It was shown to be as accurate as current approaches when analyzing conventional wings and it is able to show the details of nonplanar wing structures. This model will enable more meaningful multidisciplinary analyses of both conventional and unconventional wing designs by accurately and rapidly predicting both the weight and internal structural details of these designs. [ABSTRACT FROM AUTHOR]

This paper presents an overall performance assessment of hybrid-electric medium-range transport aircraft, with the aim to evaluate the potential of such a propulsion technology towards the reduction in the environmental impact of aviation transport, in terms of both local air quality degradation in airport areas and climate change. The proposed approach presents distinct analyses of the environmental impact of transport aircraft, distinguishing climate-changing effects from local pollution effects so that the integration of hybrid-electric propulsion is carried out to face the two issues specifically. The proposed analysis, although of conceptual nature, presents a clear scenario in which, given the technological limitations of batteries, the use of hybrid-electric propulsion on medium-haul aircraft can only be useful to reduce local pollution. In contrast, other solutions are needed to mitigate the climate-changing impact.

As a powerful numerical technique, optimization has become an inseparable part of aircraft conceptual design, but it has been seldom investigated that how to apply general design knowledge during the automatic process of optimization. This paper presents the approach of implementing a design principle for reducing the directions of radar cross section spikes of military aircraft. Once designer identifies edges in a concept and assigns parallel relations among them with the proposed methods, the relations can be automatically kept according to predefined parameter relationships during optimization, so that each feasible design point can satisfy the principle without “man-in-loop”. To validate the effectiveness of the approach, two optimization cases are finally given and discussed. [Copyright &y& Elsevier]

This paper demonstrates design of a commercial aircraft at the conceptual design stage by considering 2 objective functions i.e. minimization of aircraft maximum takeoff weight and maximization of lift-to-drag ratio multi objective evolutionary algorithms (MOEAs). Dynamic stability is taken as a design constraint while design variables include geometrical properties of the plane, consisting of the wing, empennage and fuselage. The aerodynamic coefficients of flight were calculated by using SUAVE (Aerospace Conceptual Design Environment) whereas dynamic stability analysis was achieved through using Athena vortex lattice (AVL) software. Pareto front obtained from various MOEAs are compared by Hypervolume. MOEAs are contained as MOEA / D, Two-Arch2, RPBILDE, PICEA-g, KnEA/A-ENS and KnEA. The obtained solutions for aircraft can be used for further design in the preliminary design stage.

One of the most critical regulatory issues related to supersonic flight arises from limitations imposed by community noise acceptability. The most efficient way to ensure that future supersonic aircraft will meet low-noise requirements is the verification of noise emissions from the early stages of the design process. Therefore, this paper suggests guidelines for the Landing and Take-Off (LTO) noise assessment of future civil supersonic aircraft in conceptual design. The supersonic aircraft noise model is based on the semi-empirical equations employed in the early versions of the Aircraft NOise Prediction Program (ANOPP) developed by NASA, whereas sound attenuation due to atmospheric absorption has been considered in accordance with SAE ARP 866 B. The simulation of the trajectory leads to the prediction of the aircraft noise level on ground in terms of several acoustic metrics (LAmax, SEL, PNLTM and EPNL). Therefore, a dedicated validation has been performed, selecting the only available supersonic aircraft of the Aircraft Noise and Performance database (ANP), that is, the Concorde, through the matching with Noise Power Distance (NPD) curves for LAmax and SEL, obtaining a maximum prediction error of ±2.19%. At least, an application to departure and approach procedures is reported to verify the first noise estimations with current noise requirements defined by ICAO at the three certification measurement points (sideline, flyover, approach) and to draw preliminary considerations for future low-noise supersonic aircraft design.

Stakeholders envision the introduction of electric and hybrid-electric aircraft into operation by 2035. First developments of such aircraft have demonstrated that the existing technologies do not allow realization of hybrid-electric aircraft matching the performance of traditional aircraft with the same load factors. The major challenge of future hybrid-electric aircraft development is the considerable improvement of the energetic efficiencies. This paper evaluates the (i) problems and barriers (ii) emerging and required future technologies of effective hybrid-electric propulsion systems and (iii) adaptation of the aircraft conceptual design process for the development of hybrid-electric aircraft. The developed methodology is applied to the conceptual design of a small aircraft with hybrid-electric propulsion system. The results demonstrate that the adapted conceptual design methods with (i) constrains on mass fraction adapted to new technologies and solutions, (ii) constraints defined for energy fractions for flight mission legs, (iii) considering radically new elements and technologies in aircraft design and (iv) developing unconventional aircraft, aircraft operations may allow the development of small hybrid-electric aircraft with acceptable performance. • Technology, challenges, barriers and future directions for hybrid-electric aircraft. • Conceptual design methodology adapted to small hybrid-electric aircraft. • Constraints, improved mass and energy fractions for flight mission legs. • Feasibility and performance design studies for small hybrid-electric aircraft. • Unconventional hybrid-electric aircraft concepts and solutions using design method. [ABSTRACT FROM AUTHOR]

Many-objective optimisation is a design problem, having more than 3 objective functions, which is found to be difficult to solve. Implementation of such optimisation on aircraft conceptual design will greatly benefit a design team, as a great number of trade-off design solutions are provided for further decision making. In this paper, a many-objective optimisation problem for an unmanned aerial vehicle (UAV) is posed with 6 objective functions: take-off gross weight, drag coefficient, take off distance, power required, lift coefficient and endurance subject to aircraft performance and stability constraints. Aerodynamic analysis is carried out using a vortex lattice method, while aircraft component weights are estimated empirically. A new self-adaptive meta-heuristic based on decomposition is specifically developed for this design problem. The new algorithm along with nine established and recently developed multi-objective and many-objective meta-heuristics are employed to solve the problem, while comparative performance is made based upon a hypervolume indicator. The results reveal that the proposed optimiser is the best performer for this design task. [ABSTRACT FROM AUTHOR]

The influence of variable-sweep wing on the aircraft's radar cross section (RCS) characteristics has been studied to reduce the aircraft's RCS as well as its detection probability by the hostile radar. With the help of CATIA, a 3-D digital model of the variable-sweep wing aircraft is built to generate a series of digital grids. Using MATLAB, a numerical simulation on the RCS of variable-sweep wing aircraft is conducted based on physical optics (PO) method and equivalent currents method (ECM). The results of mathematical statistics and comparative analysis show that: (i) the RCS peak value in the head direction of the aircraft decreases non-linearly with the sweep angle of the wing's leading edge; (ii) the azimuth angle corresponding to one of the peak values of the aircraft's RCS is equal to the leading edge's sweep angle; (iii) when the leading edge's sweep angle is 33°, the arithmetic average value of the RCS values in the head direction of the aircraft is 0.644% of the average value when the sweep angle is 0°; (iv) the larger the sweep angle is, the lower the probability that the aircraft is detected. [ABSTRACT FROM AUTHOR]

In the early design stages of a new aircraft, there is a strong need to broaden the knowledge base of the evolving aircraft project, allowing a profound analysis of the solution concepts and of the design driving requirements. The methodology presented in this paper provides a tool for increasing and improving in an exemplary manner the necessary information on cargo aircraft. By exchanging or adapting a few particular modules of the entire program system, the tool is applicable to a range scale of different aircraft types. In an extended requirement model, performance requirements are represented along with other operational requirements. An aircraft model is introduced in sufficient detail for conceptual design considerations. The computer-aided scaling methodology is explained, which, controlled by an optimisation module, automatically resizes the aircraft model until it optimally satisfies the requirements in terms of a selectable figure of merit. Typical results obtained at the end of the scaling are discussed together with knowledge gained during the process, and an example is given.