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Aircraft Engineering and Aerospace Technology
Journal Prestige (SJR): 0.354
Citation Impact (citeScore): 1
Number of Followers: 199  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0002-2667 - ISSN (Online) 1748-8842
Published by Emerald Homepage  [342 journals]
  • Experimental study of a pitching and plunging wing
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The complex flow behavior over an oscillating aerodynamic body, e.g. a helicopter rotor blade, a rotating wind turbine blade or the wing of a maneuvering airplane involves combinations of pitching and plunging motions. As the parameters of the problem (Re, St and phase difference between these two motions) vary, a quasi-steady analysis fails to provide realistic results for the aerodynamic response of the moving body, whereas this study aims to provide reliable experimental data. Design/methodology/approach In the present study, a pitching and plunging mechanism was designed and built in a subsonic closed-circuit wind tunnel as well as a rectangular aluminum wing of a 2:1 aspect-ratio with a NACA64-418 airfoil, used in wind turbine blades. To measure the pressure distribution along the wing chord, a number of fast responding transducers were embedded into the mid span wing surface. Simultaneous pressure measurements were conducted along the wing chord for the Reynolds number of 0.85 × 106 for both steady and unsteady cases (pitching and plunging). A flow visualization technique was used to detect the flow separation line under steady conditions. Findings Elevated pressure fluctuations coincide with the flow separation line having been detected through surface flow visualization and flattened pressure distributions appear downstream of the flow separation line. Closed hysteresis loops of the lift coefficient versus angle of attack were measured for combined pitching and plunging motions. Practical implications The experimental data can be used for improvement of unsteady fluid mechanics problem solvers. Originality/value In the present study, a new installation was built allowing the aerodynamic study of oscillating wings performing pitching and plunging motions with prescribed frequencies and phase lags between the two motions. The experimental data can be used for improvement of computational fluid dynamics codes in case that the examined aerodynamic body is oscillating.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-12T11:10:55Z
      DOI: 10.1108/AEAT-01-2017-0049
       
  • Corporate performance management: process of organizational-tailored flow
           chart
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose Main issue in management and strategy is corporate performance. Managers seek effective and strategic way to improve their performance. Authorization, which includes reputational and strategic indicators, is one of these ways. The applying authorization and using this authorization are decision-making process for managers. These processes have potential to make considerable effect on corporate performance. As a considerable result of this research that need of resource dependency type certified aircraft technicians in Anadolu University are decreased owing to this research and, also the purpose of this study is that technicians have got opportunity to creating own human resource in view of both sustainability, and competition in training field. Design/methodology/approach In this study, both specified and organizational-tailored flowchart as the problem solving techniques in decision-making process of maintenance training organization have been developed, compiled after taking the opinions of experts, for the effective implementation of type rating training, following approval, that cover the types of fleet at Anadolu University. This flowchart may guide to the relevant aircraft maintenance training organizations in their type trainings implementation process. Findings Human factor is both vital and necessary element to achieve high corporate performance. By following the flow chart, the implementation process is shortened by eliminating the difficulties in complying with the depth and complexity of the required regulation. Originality/value The development of the necessary skills and competencies of the workforce is one of the critical points for the creation, preservation and improvement of corporate value. This research has been carried out with the aim of effective utilization of institutional resources, development of personnel and hence corporate value creation. Anadolu University, which is aware of the importance of core competence, is trying to make it one of its strengths institutionally. The Anadolu University Faculty of Aeronautics and Astronautics, as an organization that has completed the necessary steps to become authorized to give type rating training, may guide other aviation organizations using the organization-specified tailored flow chart developed with the help of expert opinion.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-12T11:07:54Z
      DOI: 10.1108/AEAT-09-2017-0201
       
  • Efficient structural analysis of gas turbine blades
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this study a fast procedure for the structural analysis of gas turbine blades in aircraft engines. In this connection, investigations on the behavior of gas turbine blades concentrate on the analysis and evaluation of starting dynamics and fatigue strength. Besides, the influence of structural mistuning on the vibration characteristics of the single blade is analyzed and discussed. Design/methodology/approach A basic computation cycle is generated from a flight profile to describe the operating history of the gas turbine blade properly. Within an approximation approach for high-frequency vibrations, maximum vibration amplitudes are computed by superposition of stationary frequency responses by means of weighting functions. In addition, a two-way coupling approach determines the influence of structural mistuning on the vibration of a single blade. Fatigue strength of gas turbine blades is analyzed with a semi-analytical approach. The progressive damage analysis is based on MINER’s damage accumulation assuming a quasi-stable behavior of the structure. Findings The application to a gas turbine blade shows the computational capabilities of the approach presented. Structural characteristics are obtained by robust and stable computations using a detailed finite element model considering different load conditions. A high quality of results is realized while reducing the numerical costs significantly. Research limitations/implications The method used for analyzing the starting dynamics is based on the assumption of a quasi-static state. For structures with a sufficiently high stiffness, such as the gas turbine blades in the present work, this procedure is justified. The fatigue damage approach relies on the existence of a quasi-stable cyclic stress condition, which in general occurs for isotropic materials, as is the case for gas turbine blades. Practical implications Owing to the use of efficient analysis methods, a fast evaluation of the gas turbine blade within a stochastic analysis is feasible. Originality/value The fast numerical methods and the use of the full finite element model enable performing a structural analysis of any blade structure with a high quality of results.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-12T11:03:35Z
      DOI: 10.1108/AEAT-05-2016-0085
       
  • Maximum lift/drag ratio improvement of TUAVs via small aerodynamic
           modifications
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this study is to increase maximum lift/drag ratio (Emax) of tactical unmanned aerial vehicles (TUAVs) via applying novel small aerodynamic modifications. Design methodology/approach A TUAV is manufactured in Erciyes University, Faculty of Aeronautics and Astronautics, Model Aircraft Laboratory. It has both passive and active morphing capabilities. Its nosecone and tailcone shapes are redesigned to improve Emax. Moreover, active flow control is also built on its wing for improving Emax. Findings Using these novel small aerodynamic modifications, considerable improvement on Emax is obtained. Research limitations/implications Permission of Directorate General of Civil Aviation in Turkey is required for testing TUAVs in real-time applications. Practical implications Small aerodynamic modifications such as nosecone-tailcone shape modifications and building active flow control on wing are very beneficial for improving Emax of TUAVs. Social implications Small aerodynamic modifications satisfy confidence, high performance and easy utility demands of TUAV users. Originality/value The study will enable the creation of novel approaches to improve Emax value and therefore aerodynamic performance of TUAVs.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-11T09:54:16Z
      DOI: 10.1108/AEAT-07-2017-0175
       
  • Application of computed tomography to hole expansion measurements
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to investigate a possibility of determination of the rivet hole expansion with the use of computed tomography (CT). This method offers several benefits in comparison to the traditionally used destructive methods. Design/methodology/approach The measurements of rivet hole expansion were performed on three specimens with the use of CT. Then, the same specimens were measured with the use of the conventional destructive method. This allows to estimate accuracy of the proposed method and characterize its advantages and limitations. Findings Good correlation with the destructive method has been obtained. The proposed method enables more detailed analysis of a joint as arbitrarily oriented cross-section for analysed area can be easily generated and increase of measurements number is always possible and simple. The disadvantage of the method is lower accuracy of diameter determination than in the case of conventional methods. Research limitations/implications The measurements were performed only on one type of specimens. Probably, if a rivet and sheets were made of the same alloy, the measurements would be barely possible. The rivets were installed with squeezing ratio D/Do = 1.7 whose value is close to maximum as defined in riveting instructions (Kaniowski, 2015). This means that measured hole expansions were higher than in typical joint. The proposed method is appropriate for simple specimens (one rivet at a specimen width). Practical implications The investigation shows that rivet hole expansion can be measured with the use of CT. This method is useful especially when destruction of a specimen is not allowed or more detailed analysis is required (e.g. measurements on many depth levels). Originality/value The paper presents measurements of rivet hole expansion with the method which has not been used before for this application. Advantages and limitations of the proposed approach compared to conventional methods are discussed.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-11T09:53:16Z
      DOI: 10.1108/AEAT-01-2018-0040
       
  • Partially feasible solution space for integrated SATS operations
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to investigate the feasibility of solving an integrated flight scheduling, fleet assignment and crew pairing problem for an on-demand service using a small, up to 19-seater, aircraft. Design/methodology/approach Evolutionary algorithm is developed to solve the problem. Algorithm design assumes indirect solution representation that allows to evaluate partially feasible solutions only and speed up calculations. Tested algorithm implementation takes advantage of the graphic processing unit. Findings Performed tests confirm that the algorithm can successfully solve the defined integrated scheduling problem. Practical implications The presented algorithm allows to optimise on-demand transport service operation within minutes. Social implications Optimisation of operation cost contributes to better accessibility of transport. Originality/value The presented integrated formulation allows to avoid sub optimal solutions that are results of solving sequential sub problems. Indirect representation and evaluation strategy can be applied to speed up calculations in other problems as well.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-11T09:46:37Z
      DOI: 10.1108/AEAT-01-2018-0045
       
  • Keeping twin turbocharged engine power at flight altitudes
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is the selection and arrangement of turbochargers set for internal combustion engine which could keep engine power in an altitude of up to 12.2 km above sea level. Design/methodology/approach In the current research, the target engine, a one-dimensional four-stroke 1,600 cc piston engine has been simulated and the manufacturer’ results have been validated. Depending on engine size, three proper types of Garret turbochargers GT30, GT25 and GT20 were selected for this engine. Then, the engine and a combination of two turbochargers have been modeled one-dimensionally. A control system was used for regulation of different pressure ratios between the two turbochargers. Findings The parametric analysis shows that using the combination of GT20, GT30 turbochargers with a properly controlled pressure ratio leads to a constant output power with little changes at different altitudes which enable achieving an altitude of 12.2 km for the target engine. Practical implications Adaptation of the internal combustion engine with a twin turbocharger using one-dimensional modeling. Originality/value The one-dimensional analysis provided an overall picture of the effective performance of turbochargers functioning in different altitudes and loads. It presents a new method for adopting of turbochargers set with internal combustion engines for propulsion medium-altitude aircraft.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-11T09:45:45Z
      DOI: 10.1108/AEAT-11-2016-0200
       
  • Analysis of surveillance position error for airfield detection
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The surveillance equipment is one of the most important parts for current air traffic control systems. It provides aircraft position and other relevant information including flight parameters. However, the existing surveillance equipment has certain position errors between true and detected positions. Operators must understand and account for the characteristics on magnitude and frequency of the position errors in the surveillance systems because these errors can influence the safety of aircraft operation. This study aims to develop the simulation model for analysis of these surveillance position errors to improve the safety of aircrafts in airports. Design/methodology/approach This study investigates the characterization of the position errors observed in airport surface detection equipment of an airport ground surveillance system and proposes a practical method to numerically reproduce the characteristics of the errors. Findings The proposed approach represents position errors more accurately than an alternative simple approach. This study also discusses the application of the computational results in a microscopic simulation modeling environment. Practical implications The surveillance error is analyzed from the radar trajectory data, and a random generator is configured to implement these data. These data are used in the air transportation simulation through an application programing interface, which can be applied to the aircraft trajectory data in the simulation. Subsequently, additionally built environment data are used in the actual simulation to obtain the results from the simulation engine. Originality/value The presented surveillance error analysis and simulation with its implementation plan are expected to be useful for air transportation safety simulations.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-11T09:43:09Z
      DOI: 10.1108/AEAT-09-2017-0207
       
  • Gas turbine gas-path fault identification using nested artificial neural
           networks
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to present a quantitative fault diagnostic technique for a two-shaft gas turbine engine applications. Design/methodology/approach Nested artificial neural networks (NANNs) were used to estimate the progressive deterioration of single and multiple gas-path components in terms of mass flow rate and isentropic efficiency indices. The data required to train and test this method are attained from a thermodynamic model of the engine under steady-state conditions. To evaluate the tolerance of the method against measurement uncertainties, Gaussian noise values were considered. Findings The test results revealed that this proposed method is capable of quantifying single, double and triple component faults with a sufficiently high degree of accuracy. Moreover, the authors confirmed that NANNs have derivable advantages over the single structure-based methods available in the public domain, particularly over those designed to perform single and multiple faults together. Practical implications This method can be used to assess engine’s health status to schedule its maintenance. Originality/value For complicated gas turbine diagnostic problems, the conventional single artificial neural network (ANN) structure-based fault diagnostic technique may not be enough to get robust and accurate results. The diagnostic task can rather be better done if it is divided and shared with multiple neural network structures. The authors thus used seven decentralized ANN structures to assess seven different component fault scenarios, which enhances the fault identification accuracy significantly.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-11T09:41:17Z
      DOI: 10.1108/AEAT-01-2018-0013
       
  • Bio-inspired aircraft control
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose This paper aims to present a state-of-the-art review in various fields of interest, leading to a new concept of bio-inspired control of small aircraft. The main goal is to improve controllability and safety in flying at low speeds. Design/methodology/approach The review part of the paper gives an overview of artificial and natural flow sensors and haptic feedback actuators and applications. This background leads to a discussion part where the topics are synthesized and the trend in control of small aircraft is estimated. Findings The gap in recent aircraft control is identified in the pilot–aircraft interaction. A pilot’s sensory load is discussed and several recommendations for improved control system architecture are laid out in the paper. Practical implications The paper points out an opportunity for a following research of suggested bio-inspired aircraft control. The control is based on the artificial feeling of aerodynamic forces acting on a wing by means of haptic feedback. Originality/value The paper merges two research fields – aircraft control and human–machine interaction. This combination reveals new possibilities of aircraft control.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-11T09:38:15Z
      DOI: 10.1108/AEAT-01-2017-0020
       
  • Investigation on the benefit of formation flight with a focus on the
           leading and trailing aircraft rotation
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to study the potential advantages of aircraft formation flight (FF) and to exploit further benefits through exchanging the leading positions. Design/methodology/approach The detailed and robust methodologies concerning FF mission analysis including the leading aircraft rotation strategies are developed in this paper to study the fuel burn benefit and the additional bonus of formation rotation. Findings Switch of FF leading positions can offset the undesired weight ratios between the leading and trailing aircraft within FF missions, which further alleviates the deviations from design flight conditions. The case studies on two long-range civil transport aircraft in FF show that the leading and trailing aircraft can achieve almost equal fuel benefit through rotations. As compared to FF without rotation, the fuel efficiency can be improved by more than 11 per cent. Research limitations/implications The work can bring benefit the research communities as a fundamental basis for operational studies of FF, such as FF airspace management in the future, which is significant for a future real-world implementation of FFs. Practical implications According to the authors’ study, equal or quasi-equal fuel savings can be achieved if the rotation is properly arranged. For the real-world FF application, fuel consumption (FC) or cost redistribution problem for leading and trailing aircraft belonging to two different operating airlines can therefore be resolved through the concept proposed by the paper. Originality/value The methods developed in the paper have the advantage to give more reliable estimations of the achievable fuel burn savings of FF. The concept proposed in the paper has significant meaning with respect to offset the undesired weight ratios between the leading and trailing aircraft within FF missions and redistributing FC or cost redistribution of different operating airlines.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-11T02:48:52Z
      DOI: 10.1108/AEAT-07-2017-0162
       
  • Distributed measurement system based on CAN data bus
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose This paper aims to describe the idea behind and design of a miniaturized distributed measurement system based on a controller area network (CAN) data bus. Design/methodology/approach The intention of the designers was to build a light and modular measurement system which can be used in remotely piloted aircraft systems and ultra-light aircraft during flight tests, as well as normal operation. The structure of this distributed measurement system is based on a CAN data bus. The CAN aerospace standard has been applied to the software as well as the hardware comprising this system. PRP-W2 software designed for PCs is an additional component of the proposed measurement system. This software supports data acquisition from a recorder unit and allows for preliminary data analysis, as well as data conversion and presentation. Findings The system, complete with a high-speed data recorder, was successfully installed on board of an MP-02 Czajka aircraft. A research experiment using the system and oriented on airframe high frequency vibration analysis is presented in the final part of this paper. Research limitations/implications This measurement system allows analysis of high-frequency vibrations occurring at selected points of the aircraft. A data set is recorded by three-axis accelerometers and gyroscopes at frequencies up to 1 kHz. Practical implications The use of a miniature and lightweight modular measurement system will, in many cases, be faster and less expensive than full-scale measurement and data acquisition systems, which often require a lengthy assembly process. The implementation of this class of lightweight flight test systems has many advantages, in particular to the operation of small aircraft. Such solutions are likely to become increasingly common in unmanned aerial vehicles and in other light aircraft in the future. Originality/value The introduction of high-frequency multi-point measurements on the board of small and miniature aircraft.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-11T02:45:38Z
      DOI: 10.1108/AEAT-11-2017-0247
       
  • Aircraft model for automatic taxi directional control system design
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose This paper aims to present a concept of an automatic directional control system of remotely piloted aerial system (RPAS) during the taxiing phase. In particular, it shows the initial stages of the control laws synthesis – mathematical model and simulation of taxiing aircraft. Several reasons have emerged in recent years that make the automation of taxiing an important design challenge including decreased safety, performance and pilot workload. Design/methodology/approach The adapted methodology follows the model-based design approach in which the control system and the aircraft are mathematically modelled to allow control laws synthesis. The computer simulations are carried out to analyse the model behaviour. Findings Chosen methodology and modelling technique, especially tire-ground contact model, resulted in a taxing aircraft model that can be used for directional control law synthesis. Aerodynamic forces and moments were identified in the wind tunnel tests for the full range of the slip angle. Simulations allowed to compute the critical speeds for different taxiway conditions in a 90° turn. Practical implications The results can be used for the taxi directional control law synthesis and simulation of the control system. The computed critical speeds can be treated as safety limits. Originality/value The taxi directional control system has not been introduced to the RPAS yet. Therefore, the model of taxiing aircraft including aerodynamic characteristics for the full range of the slip angle has a big value in the process of design and implementation of the future auto taxi systems. Moreover, computed speed safety limits can be used by designers and standard creators.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-11T02:42:40Z
      DOI: 10.1108/AEAT-06-2018-0161
       
  • Flow-separation-control system operating in feedback closed loop
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this study is to develop the concept of self-adapting system which would be able to control a flow on the wing-high-lift system and protect the flow against strong separation. Design/methodology/approach The self-adapting system has been developed based on computational approach. The computational studies have been conducted using the URANS solver. The experimental investigations have been conducted to verify the computational results. Findings The developed solution is controlled by closed-loop-control (CLC) system. As flow actuators, the main-wing trailing-edge nozzles are proposed. Based on signals received from the pressure sensors located at the flap trailing edge, the CLC algorithm changes the amount of air blown from the nozzles. The results of computational simulations confirmed good effectiveness and reliability of the developed system. These results have been partially confirmed by experimental investigations. Research limitations/implications The presented research on an improvement of the effectiveness of high-lift systems of modern aircraft was conducted on the relatively lower level of the technology readiness. However, despite this limitation, the results of presented studies can provide a basis for developing innovative self-adaptive aerodynamic systems that potentially may be implemented in future aircrafts. Practical implications The studies on autonomous flow-separation control systems, operating in a closed feedback loop, are a great hope for significant advances in modern aeronautical engineering, also in the UAV area. The results of the presented studies can provide a basis for developing innovative self-adaptive aerodynamic systems at a higher level of technological readiness. Originality/value The presented approach is especially original and valuable in relation to the innovative concept of high-lift system supported by air-jets blown form the main-wing-trailing-edge nozzles; the effective and reliable flow sensors are the pressure sensors located at the flap trailing edge, and the effective and robust algorithm controlling the self-adapting aerodynamic system – original especially in respect to a strategy of deactivation of flow actuators.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-11T02:17:57Z
      DOI: 10.1108/AEAT-12-2017-0270
       
  • Constrained airfoil optimization using the area-preserving free-form
           deformation
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is the presentation of a technique to be integrated in a numerical airfoil optimization scheme, for the exact satisfaction of a strict equality cross-sectional area constraint. Design/methodology/approach An airfoil optimization framework is presented, based on Area-Preserving Free-Form Deformation (AP FFD) technique. A parallel metamodel-assisted differential evolution (DE) algorithm is used as an optimizer. In each generation of the DE algorithm, before the evaluation of the fitness function, AP FFD is applied to each candidate solution, via coupling a classic B-Spline-based FFD with an area correction step. The area correction step is achieved by solving a sub problem, which consists of computing and applying the minimum possible offset to each one of the free-to-move control points of the FFD lattice, subject to the area preservation constraint. Findings The proposed methodology is able to obtain better values of the objective function, compared to both a classic penalty function approach and a generic framework for handling constraints, which suggests the separation of constraints and objectives (separation-sub-swarm), without any loss of the convergence capabilities of the DE algorithm, while it also guarantees an exact area preservation. Due to the linearity of the area constraint in each axis, the extraction of an inexpensive closed-form solution to the sub problem is possible by using the method of Lagrange multipliers. Practical implications AP FFD can be easily incorporated into any 2D shape optimization/design process, as it is a time-saving and easy-to-implement repair algorithm, independent from the nature of the problem at hand. Originality/value The proposed methodology proved to be an efficient tool in facing airfoil design problems, enhancing the rigidity of the optimal airfoil by preserving its cross-sectional area to a predefined value.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-10T07:46:15Z
      DOI: 10.1108/AEAT-10-2016-0184
       
  • Comparison of flutter calculation methods based on ground vibration test
           result
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      PurposeA low-cost but credible method of low-subsonic flutter analysis based on ground vibration test (GVT) results is presented. The purpose of this paper is a comparison of two methods of immediate flutter problem solution: JG2 – low cost software based on the strip theory in aerodynamics (STA) and V-g method of the flutter problem solution and ZAERO I commercial software with doublet lattice method (DLM) aerodynamic model and G method of the flutter problem solution. In both cases, the same sets of measured normal modes are used. Design/methodology/approachBefore flutter computation, resonant modes are supplied by some non-measurable but existing modes and processed using the author’s own procedure. For flutter computation, the modes are normalized using the aircraft mass model. The measured mode orthogonalization is possible. The flutter calculation made by means of both methods are performed for the MP-02 Czajka UL aircraft and the Virus SW 121 aircraft of LSA category. FindingsIn most cases, both compared flutter computation results are similar, especially in the case of high aspect wing flutter. The Czajka T-tail flutter analysis using JG2 software is more conservative than the one made by ZAERO, especially in the case of rudder flutter. The differences can be reduced if the proposed rudder effectiveness coefficients are introduced. Practical implicationsThe low-cost methods are attractive for flutter analysis of UL and light aircraft. The paper presents the scope of the low-cost JG2 method and its limitations. Originality/valueIn comparison with other works, the measured generalized masses are not used. Additionally, the rudder effectiveness reduction was implemented into the STA. However, Niedbal (1997) introduced corrections of control surface hinge moments, but the present work contains results in comparison with the outcome obtained by means of the more credible software.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-09T09:53:38Z
      DOI: 10.1108/AEAT-03-2018-0102
       
  • Aerodynamic characteristics of helicopter engine side air intakes
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      PurposeAerodynamic characteristics of engine side air intakes for a lightweight helicopter are investigated aiming to achieve an efficient engine airframe integration. Design/methodology/approachOn a novel full-scale model of a helicopter fuselage section, a comprehensive experimental data set is obtained by wind tunnel testing. Different plenum chamber types along with static side intake and semi-dynamic side intake configurations are considered. Engine mass flow rates corresponding to the power requirements of realistic helicopter operating conditions are reproduced. For a variety of freestream velocities and mass flow rates, five-hole pressure probe data in the aerodynamic interface plane and local surface pressure distributions are compared for the geometries. FindingsIn low-speed conditions, unshielded, sideways facing air intakes yield lowest distortion levels and total pressure losses. In fast forward flight condition, a forward-facing intake shape is most beneficial. Additionally, the influence of an intake grid and plenum chamber splitter is evaluated. Originality/valueThe intake testing approach and the trends found can be applied to other novel helicopter intakes in early development stages to improve engine airframe integration and decrease development times.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-09T08:52:28Z
      DOI: 10.1108/AEAT-03-2017-0082
       
  • Method of electrical connector intermittent fault reproduction
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      PurposeThis paper aims to reproduce the electrical connector intermittent fault behaviours with step-up vibration stress while maintaining the integrity of the product. Design/methodology/approachA dynamic model of an electrical connector under vibration is established for contact resistance analysis. Next, the dynamic characteristics of contact resistance are analysed, and cumulative damage theory is used to calculate the damage under different stresses during the intermittent fault reproduction test. To reduce damage and improve efficiency, the step-up stress is used for the reproduction test. FindingsThe proposed method can reproduce the intermittent fault behaviour, and the step-up stress test is more efficient than the constant stress test. Research limitations/implicationsStep-up stress is used for intermittent fault reproduction, and the quantitative relationships between intermittent fault and product damage can be further studied. Practical implicationsIt is expected that the proposed methodology can help engineers to reproduce the intermittent fault behaviours to facilitate the detection and diagnosis of intermittent fault and to improve equipment safety. Originality/valueThe mechanism of electrical connector reproduction is analysed and the step-up stress test is used for intermittent fault reproduction.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-09T08:48:49Z
      DOI: 10.1108/AEAT-12-2016-0253
       
  • Topology optimization of a novel fuselage structure in the conceptual
           design phase
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose In recent years, innovative aircraft designs have been investigated by researchers to address the environmental and economic issues for the purpose of green aviation. To keep air transport competitive and safe, it is necessary to maximize design efficiencies of the aircrafts in terms of weight and cost. The purpose of this paper is to focus on the research which has led to the development of a novel lattice fuselage design of a forward-swept wing aircraft in the conceptual phase by topology optimization technique. Design/methodology/approach In this paper, the fuselage structure is modelled with two different types of elements – 1D beam and 2D shell – for the validation purpose. Then, the finite element analysis coupled with topology optimization is performed to determine the structural layouts indicating the efficient distributed reinforcements. Following that, the optimal fuselage designs are obtained by comparison of the results of 1D and 2D models. Findings The topological results reveal the need for horizontal stiffeners to be concentrated near the upper and lower extremities of the fuselage cross section and a lattice pattern of criss-cross stiffeners should be well-placed along the sides of the fuselage and near the regions of window locations. The slight influence of windows on the optimal reinforcement layout is observed. To form clear criss-cross stiffeners, modelling the fuselage with 1D beam elements is suggested, whereas the less computational time is required for the optimization of the fuselage modelled using 2D shell elements. Originality/value The authors propose a novel lattice fuselage design in use of topology optimization technique as a powerful design tool. Two types of structural elements are examined to obtain the clear reinforcement detailing, which is also in agreement with the design of the DLR (German Aerospace Center) demonstrator. The optimal lattice layout of the stiffeners is distinctive to the conventional semi-monocoque fuselage design and this definitely provides valuable insights into the more efficient utilization of composite materials for novel aircraft designs.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-08T11:44:16Z
      DOI: 10.1108/AEAT-04-2017-0100
       
  • Suppression of nonlinear aeroelastic vibrations by learned neural network
           controller
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of the paper is to analyze the active suppression of the aeroelastic vibrations of ailerons with strongly nonlinear characteristics by neural network/reinforcement learning (NN/RL) control method and comparing it with the classic robust methods of suppression. Design/methodology/approach The flexible wing and aileron with hysteresis nonlinearity is treated as a plant-controller system and NN/RL and robust controller are used to suppress the nonlinear aeroelastic vibrations of aileron. The simulation approach is used for analyzing the efficiency of both types of methods in suppressing of such vibrations. Findings The analysis shows that the NN/RL controller is able to suppress the nonlinear vibrations of aileron much better than linear robust method, although its efficiency depends essentially on the NN topology as well as on the RL strategy. Research limitations/implications Only numerical analysis was carried out; thus, the proposed solution is of theoretical value, and its application to the real suppression of aeroelastic vibrations requires further research. Practical implications The work shows the NN/RL method has a great potential in improving suppression of highly nonlinear aeroelastic vibrations, opposed to the classical robust methods that probably reach their limits in this area. Originality/value The work raises the questions of controllability of the highly nonlinear aeroelastic systems by means of classical robust and NN/RL methods of control.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-08T11:39:34Z
      DOI: 10.1108/AEAT-01-2018-0019
       
  • UAV application for precision agriculture
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this study is to show the potentials of a cost-effective unmanned aerial vehicles (UAV) system for agriculture industry. The current population growth rate is so vast that farming industry must be highly efficient and optimized. As a response for high quality food demands, the new branch of the agriculture industry has been formed – the precision agriculture. It supports farming process with sensors, automation and innovative technologies. The UAV advantages over regular aviation are withering. Not only they can fly at lower altitude and are more precise but also offer same high quality and are much cheaper. Design/methodology/approach The main objective of this project was to implement an exemplary cost-effective UAV system with electronic camera stabilizer for gaining useful data for agriculture. The system was based on small, unmanned flying wing able to perform fully autonomous missions, a commercially available camera and an own-design camera stabilizer. The research plan was to integrate the platform and run numerous experimental flights over farms, fields and woods collecting aerial pictures. All the missions have been planned to serve for local farming and forest industries and cooperated with local business authorities. Findings In preliminary flight tests, the variety of geodetic, forest and agriculture data have been acquired, placed for post processing and applied for the farming processes. The results of the research were high quality orthophoto maps, 3D maps, digital surface models and images mosaics with normalized difference vegetation index. The end users were astonished with the high-quality results and claimed the high importance for their business. Originality/value The case study results proved that this kind of a small UAV system is exceptional to manage and optimize processes at innovative farms. So far only professional, high-cost UAV platforms or traditional airships have been applied for agriculture industry. This paper shows that even simple, commercially available equipment could be used for professional applications.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-08T11:35:33Z
      DOI: 10.1108/AEAT-01-2018-0056
       
  • Bending and vibration analysis of skew sandwich plate
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to develop a general mathematical model for the evaluation of the bending and vibration responses of the skew sandwich composite plate using higher-order shear deformation theory. The sandwich structural components are highly preferable in modern engineering application because of their desirable structural advantages despite the manufacturing and analysis complexities. The present model is developed to solve the bending and vibration problem of the skew sandwich composite plate with adequate accuracy numerically in the absence of the experimental analysis. Design/methodology/approach The skew sandwich composite plate structure is modelled in the present analysis by considering laminated face sheet in conjunction with isotropic and/or orthotropic core numerically with the help of the higher-order mathematical model. Further, the responses are computed numerically with the help of in-house computer code developed in matrix laboratory (MATLAB) environment in conjunction with finite element (FE) steps. The system governing equations are derived via variational technique for the computation of the static and the frequency responses. Findings The skew sandwich composite plate is investigated using the higher-order kinematic model where the transverse displacement through the thickness is considered to be linear. The convergence and the validation study of the bending and the frequency values of the sandwich structure indicate the necessary accuracy. Further, the current model has been used to highlight the applicability of the higher-order kinematics for the evaluation of the sandwich structural responses (frequency and static deflections) for different design parameters. Originality/value In the present paper, the bending and the vibration responses of the skew sandwich composite plate are analysed numerically using the equivalent single-layer higher-order kinematic theory for the isotropic and the orthotropic core numerically with the help of isoparametric FE steps. Finally, it is understood that the present model is capable of solving the sandwich structural responses with less computation cost and adequate accuracy.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-08T11:31:52Z
      DOI: 10.1108/AEAT-05-2016-0087
       
  • Flight path optimization with application to in-flight replanning to
           changing destinations
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to present a new approach for finding a minimum-length trajectory for an autonomous unmanned air vehicle or a long-range missile from a release point with specified release conditions to a destination with specified approach conditions. The trajectory has to avoid obstacles and no-fly zones and must take into account the kinematic constraints of the air vehicle. Design/methodology/approach A discrete routing model is proposed that represents the airspace by a sophisticated network. The problem is then solved by applying standard shortest-path algorithms. Findings In contrast to the most widely used grids, the generated networks allow arbitrary flight directions and turn angles, as well as maneuvers of different strengths, thus fully exploiting the flight capabilities of the aircraft. Moreover, the networks are resolution-independent and provide high flexibility by the option to adapt density. Practical implications As an application, a concept for in-flight replanning of flight paths to changing destinations is proposed. All computationally intensive tasks are performed in a pre-flight planning prior to the launch of the mission. The in-flight planning is based entirely on precalculated data, which are stored in the onboard computer of the air vehicle. In particular, no path finding algorithms with high or unpredictable running time and uncertain outcome have to be applied during flight. Originality/value The paper presents a new network-based algorithm for flight path optimization that overcomes weaknesses of grid-based approaches and allows high-quality solutions. The method can be applied for quick in-flight replanning of flight paths.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-08T11:24:47Z
      DOI: 10.1108/AEAT-05-2016-0088
       
  • Analysis and optimization of morphing wing aerodynamics
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to present a method for analysis and optimization of morphing wing. Moreover, a numerical advantage of morphing airfoil wing, typically assessed in simplified two-dimensional analysis is found using higher fidelity methods. Design/methodology/approach Because of multi-point nature of morphing wing optimization, an approach for optimization by analysis is presented. Starting from naïve parametrization, multi-fidelity aerodynamic data are used to construct response surface model. From the model, many significant information are extracted related to parameters effect on objective; hence, design sensitivity and, ultimately, optimal solution can be found. Findings The method was tested on benchmark problem, with some easy-to-predict results. All of them were confirmed, along with additional information on morphing trailing edge wings. It was found that wing with morphing trailing edge has around 10 per cent lower drag for the same lift requirement when compared to conventional design. Practical implications It is demonstrated that providing a smooth surface on wing gives substantial improvement in multi-purpose aircrafts. Details on how this is achieved are described. The metodology and results presented in current paper can be used in further development of morphing wing. Originality/value Most of literature describing morphing airfoil design, optimization or calculations, performs only 2D analysis. Furthermore, the comparison is often based on low-fidelity aerodynamic models. This paper uses 3D, multi-fidelity aerodynamic models. The results confirm that this approach reveals information unavailable with simplified models.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-08T11:20:46Z
      DOI: 10.1108/AEAT-12-2017-0289
       
  • Designing flow chart for aircraft type training in aviation training
           process management
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose Training management has critical in developing of civil aviation sector in Turkey. It requires using serious corporate sources for this reason is directly topic of aviation management and strategy.it is also about process management. According to this view, this paper aims to become a guidance to management training for maintenance or training organisations in the aviation sector wishing to obtain the authorisation, given national civil aviation authority (Directorate General of Civil Aviation), of providing type rating trainings that cover the types of aeroplanes including Beech 90 Series, Socata TB Series and Cessna/Reims-Cessna 172/F172 Series. Design/methodology/approach Aviation training organisations must be managed according to aviation law and regulations. It includes several approval processes about training content. Managers must be organising their resources, and they should get well timely decision made in optimum time. In this study, a flowchart, that is the procedure to follow in accordance with the related aviation regulations, has been developed while taking the opinion of experts and using experience gained from the approval process for the type trainings. This flowchart may gain time to managers in their approval process. It may use as guidance to create optimum flow in their process management. Findings The purpose of flowchart developed is to shorten the authorisation processes of the relative institutions by eliminating the challenges caused by the excess and complexity of national or international regulations related to the of authorisation of aircraft type rating training. Originality/value It is important to gain authority. But more important is to manage the authority as sustainable way in aviation training. Loosing authority in specific field may effect on both corporate reputation and doing aviation business. Anadolu University manages related risk via scientific project during using their authorisation. The results developed as a result of the expert opinions and the experience gained during the aircraft type training authorisation process will contribute to the literature. When considered from this point of view, it is expected for this study to fill an important gap in the literature. It is highly important for the aviation sector in terms of evaluating and interpreting academically such a process for practice, and also raising awareness or providing awareness for similar practices. It may also useful for process management.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-02T01:44:22Z
      DOI: 10.1108/AEAT-03-2017-0096
       
  • Neural network based redesign of morphing UAV for simultaneous improvement
           of roll stability and maximum lift/drag ratio
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The aim of this paper is to redesign of morphing unmanned aerial vehicle (UAV) using neural network for simultaneous improvement of roll stability coefficient and maximum lift/drag ratio. Design/methodology/approach Redesign of a morphing our UAV manufactured in Faculty of Aeronautics and Astronautics, Erciyes University is performed with using artificial intelligence techniques. For this purpose, an objective function based on artificial neural network (ANN) is obtained to get optimum values of roll stability coefficient (Clβ) and maximum lift/drag ratio (Emax). The aim here is to save time and obtain satisfactory errors in the optimization process in which the ANN trained with the selected data is used as the objective function. First, dihedral angle (φ) and taper ratio (λ) are selected as input parameters, C*lβ and Emax are selected as output parameters for ANN. Then, ANN is trained with selected input and output data sets. Training of the ANN is possible by adjusting ANN weights. Here, ANN weights are adjusted with artificial bee colony (ABC) algorithm. After adjusting process, the objective function based on ANN is optimized with ABC algorithm to get better Clβ and Emax, i.e. the ABC algorithm is used for two different purposes. Findings By using artificial intelligence methods for redesigning of morphing UAV, the objective function consisting of C*lβ and Emax is maximized. Research limitations/implications It takes quite a long time for Emax data to be obtained realistically by using the computational fluid dynamics approach. Practical implications Neural network incorporation with the optimization method idea is beneficial for improving Clβ and Emax. By using this approach, low cost, time saving and practicality in applications are achieved. Social implications This method based on artificial intelligence methods can be useful for better aircraft design and production. Originality/value It is creating a novel method in order to redesign of morphing UAV and improving UAV performance.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-02T01:40:40Z
      DOI: 10.1108/AEAT-06-2017-0157
       
  • Innovative exploration of safe in-flightcrew escape options
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to explore various in-flight crew escape options of a prototype transport aircraft and finalize the option offering safest crew egress for different combinations of contingencies and flight conditions. Design/methodology/approach Various egress options were explored through simulation in a computational fluid dynamics (CFD) software using aircraft 3D CAD model and scalable digital mannequins. For this, certain important contingencies which best describe the extreme aircraft behaviour were identified. Crew escape options, which have least external interference in expected egress trajectory, were selected. Several test simulations representing each feasible combination of contingency, escape option and flight condition were simulated. The option which offers safe crew escape in each test case is deemed to be the safest egress option for the test aircraft. Findings Among five options explored, crew escape through forward ventral hatch provided the safest crew escape for all test cases. The selected option was validated for robustness with additional test cases modelling different anthropometric characteristics of 5th and 50th percentile pilot populations with different postures. Originality/value In-flight validation of safe crew escape option is infeasible by actual trial. Exploration of safe crew options for required number of test cases by any analytical method or by wind tunnels tests is tedious, time consuming and extremely expensive. On the other hand, exploration of safest crew option by CFD, besides being first of its kind, provides convenient option to configure, test and validate different test cases with unmatched benefits in time, cost and simplicity.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-02T01:35:59Z
      DOI: 10.1108/AEAT-09-2016-0151
       
  • Development taxonomy of human risk factors for corporate sustainability in
           aviation sector
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose Contemporary management and strategy mean optimization of ingredient factors such as human factors, systems, operations and equipment. With system approach in management and strategy, human risk factor as input has considerable potential to change results as airworthiness in aviation management. The managers of aviation business also optimize their functions to act safe while making contribution to development in triple of sustainability as economic development and its sustainability; social development and its sustainability; and environmental development and its sustainability. Corporate sustainability can be accomplished via supporting workforce which is the human risk factor. To support (empowerment) workforce, researchers should identify human risk or error factors which are important to this research. The purpose of this study is to suggest holistic framework for working environment system of aircraft maintenance technicians (AMTs) within two respects such as human performance (ergonomics) and corporate performance (sustainability). The secondary purpose of this system is to develop human risk taxonomy by determining the factors affecting both human and work by taking ergonomic aspects in aviation. Design/methodology/approach In this study, a taxonomy of human risk factors for AMTs is developed. These human factors divided into groups and subfactors are obtained from an extensive literature review and experts’ opinions in the field of human performance in aviation. Taxonomy developed will be useful to both sharing and using corporate sources in sustainable way. Findings Human risk factors can be considered or accepted as factors that cause human error. This may result in the optimum way to managing human risk factor via minimizing human-based error. Personality, hazardous attitudes, individual characteristics, physical/psychological condition of AMTs and corporate social responsibility factors are human-related risk variables in this study. The risks and error can be reduced by recognizing these factors and revealing their relation to ergonomic design. Originality/value The results of this study are intended to constitute a guide for managers to manage risk factors and to take corrective and preventive actions for their maintenance operations. It is believed that this study is highly important for the aviation sector in terms of raising awareness or providing awareness for similar practices. As taxonomy of the risk factors contributes to the managing human error, corrective actions related to these factors must be taken by managers.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-02T01:31:39Z
      DOI: 10.1108/AEAT-04-2018-0133
       
  • A numerical study into the longitudinal dynamic stability of the tailless
           aircraft
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this research is a study into a mathematical approach of a tailless aircraft dynamic stability analysis. This research is focused on investigation of influence of elevons (elevator) on stability derivatives and consequently on the aircraft longitudinal dynamic stability. The main research question is to determine whether this impact should be taken into account on the conceptual and preliminary stage of the analysis of the longitudinal dynamic stability. Design/methodology/approach Aerodynamic coefficients and longitudinal stability derivatives were computed by Panukl (panel methods). The analysis of the dynamic stability of the tailless aircraft was made by the Matlab code and SDSA package. Findings The main result of the research is a comparison of the dynamic stability of the tailless aircraft for different approaches, with and without the impact of elevator deflection on the trim drag and stability derivatives. Research limitations/implications This paper presents research that mostly should be considered on the preliminary stage of aircraft design and dynamic stability analysis. The impact of elevons deflection on the aircraft moment of inertia has been omitted. Practical implications The results of this research will be useful for the further design of small tailless unmanned aerial vehicles (UAVs). Originality/value This research reveals that in case of the analysis of small tailless UAVs, the impact of elevons deflection on stability derivatives is bigger than the impact of a Mach number. This impact should be taken into consideration, especially for a phugoid mode.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-02T01:26:19Z
      DOI: 10.1108/AEAT-01-2018-0032
       
  • A new fuel-balanced formation keeping reference trajectories planning
           method
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to propose a new fuel-balanced formation keeping reference trajectories planning method based on selecting the virtual reference center(VRC) in a fuel-balanced sense in terms of relative eccentricity and inclination vectors (E/I vectors). Design/methodology/approach By using the geometrical intuitive relative E/I vectors theory, the fuel-balanced VRC selection problem is reformulated as the geometrical problem to find the optimal point to equalize the distances between the VRC and the points determined by the relative E/I vectors of satellites in relative E/I vectors plane, which is solved by nonlinear programming method. Findings Numerical simulations demonstrate that the new proposed fuel-balanced formation keeping strategy is valid, and the new method achieves better fuel-balanced performance than the traditional method, which keeps formation with respect to geometrical formation center. Research limitations/implications The new fuel-balanced formation keeping reference trajectories planning method is valid for formation flying mission whose member satellite is in circular or near circular orbit in J2 perturbed orbit environment. Practical implications The new fuel-balanced formation keeping reference trajectories planning method can be used to solve formation flying keeping problem, which involves multiple satellites in the formation. Originality/value The fuel-balanced reference trajectories planning problem is reformulated as a geometrical problem, which can provide insightful way to understand the dynamic nature of the fuel-balanced reference trajectories planning issue.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-02T01:22:19Z
      DOI: 10.1108/AEAT-03-2017-0084
       
  • Tensile strength of GFRP and hybrid composites under various environmental
           conditions
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to study the mechanical behavior of glass fiber reinforced polymer (GFRP) and hybrid composites under various adverse environmental conditions. This mainly helps the researchers to overcome the obstacles that have been met when they use the materials individually and also to know the impacts of environment on them. Design/methodology/approach The GFRP and hybrid specimens are made according to the American Society for Testing and Materials standard. The specimens are then immersed in aviation turbine fuel, hydraulic fluid and concentrated sulfuric acid. The tensile strength of the specimens is then determined using the universal testing machine. Findings The tensile strengths of the normal specimens and the specimens subjected to various environmental conditions are determined. The results obtained for GFRP and hybrid specimens are then compared. Research limitations/implications The researchers can extend the time intervals further for a better understanding of the strength of the composites. Practical implications Once better combinations are found out with the highest strength to weight ratio and its resistance to various adverse environmental conditions, it can be used in real-time applications. Social implications The best hybrid combinations can be used in place of metals in future. Originality/value This is an original research and is clearly based on the experimental results, so it adds very much value to the aviation industry because strength to weight ratio is one of the major issues to be taken into consideration.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-02T01:12:58Z
      DOI: 10.1108/AEAT-09-2017-0199
       
  • Aerodynamic and flight dynamic interaction in spin
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to describe an integrated approach to spin analysis based on 6-DOF (degrees of freedom) fully nonlinear equations of motion and a three-dimensional multigrid Euler method used to specify a flow model. Another purpose of this study is to investigate military trainer performance during a developed phase of a deliberately executed spin, and to predict an aircraft tendency while entering a spin and its response to control surface deflections needed for recovery. Design/methodology/approach To assess spin properties, the calculations of aerodynamic characteristics were performed through an angle-of-attack range of −30 degrees to +50 degrees and a sideslip-angle range of −30 degrees to +30 degrees. Then, dynamic equations of motion of a rigid aircraft together with aerodynamic loads being premised on stability derivatives concept were numerically integrated. Finally, the examination of light turboprop dynamic behaviour in post-stalling conditions was carried out. Findings The computational method used to evaluate spin was positively verified by comparing it with the experimental outcome. Moreover, the Euler code-based approach to lay down aerodynamics could be considered as reliable to provide high angles-of-attack characteristics. Conclusions incorporate the results of a comparative analysis focusing especially on comprehensive assessment of output data quality in relation to flight tests. Originality/value The conducted calculations take into account aerodynamic and flight dynamic interaction of an aerobatic-category turboprop in spin conditions. A number of manoeuvres considering different aircraft configurations were simulated. The computational outcomes were subsequently compared to the results of in-flight tests and the collected data were thoroughly analysed to draw final conclusions.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-02T01:09:38Z
      DOI: 10.1108/AEAT-01-2018-0042
       
  • Comparing fluid ring and CMG servomechanisms for active control of rigid
           satellites
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose This paper aims to describe a novel type of attitude control system (ACS) in different configurations. This servomechanism is compared with control moment gyro (CMG) in significant parameters of performance for ACS of rigid satellite. Design/methodology/approach This new actuator is the fluid containing one or more rings and fluid flow is supplied by pump. The required torque control is obtained by managing fluid angular velocity. The cube-shaped satellite with three rings of fluid in the principle axes is considered for modeling. The satellite is considered rigid and nonlinear dynamics equation is used for it. In addition, the failure of the pyramid-shaped satellite with an additional ring fluid is discussed. Findings The controller model for four fluid rings has more complexity than for three fluid rings. The simulation results illustrated that four fluid rings need less energy for stabilization than three fluid rings. The performance of this type of actuator is compared with CMG. At last, it is demonstrated that performance parameters are improved with fluid ring actuator. Research limitations/implications Fluid ring actuator can be affected by environmental pressure and temperature. Therefore, freezing and boiling temperature of the fluid should be considered in system designation. Practical implications Fluid ring servomechanism can be used as ACS in rigid satellites. This actuator is compared by CMG, the prevalent actuator. It has less displacement attitude maneuver. Originality/value The results provide the feasibility and advantages of using fluid rings as satellite ACS. The quaternion error controller is used for this model to enhance its performance.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-10-02T01:03:38Z
      DOI: 10.1108/AEAT-01-2017-0039
       
  • Guidance law to control impact time constraining the seeker’s field
           of view'
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to present a novel guidance law that is able to control the impact time while the seeker’s field of view (FOV) is constrained. Design/methodology/approach The new guidance law is derived from the framework of Lyapunov stability theory to ensure interception at the desired impact time. A time-varying guidance gain scheme is proposed based on the analysis of the convergence time of impact time error, where finite-time stability theory is used. The circular trajectory assumption is adopted for the derivation of accurate analytical estimation of time-to-go. The seeker’s FOV constraint, along with missile acceleration constraint, is considered during guidance law design, and a switching strategy to satisfy it is designed. Findings The proposed guidance law can drive missile to intercept stationary target at the desired impact time, as well as satisfies seeker’s FOV and missile acceleration constraints during engagement. Simulation results show that the proposed guidance law could provide robustness against different engagement scenarios and autopilot lag. Practical implications The presented guidance law lays a foundation for using cooperative strategies, such as simultaneous attack. Originality/value This paper presents further study on the impact time control problem considering the seeker’s FOV constraint, which conforms better to reality.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-09-27T02:51:19Z
      DOI: 10.1108/AEAT-06-2017-0151
       
  • Propeller thrust force contribution to airplane longitudinal stability
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose This paper aims to present the new information about propeller thrust force contribution to airplane longitudinal stability analysis. Design/methodology/approach The method presented in this paper is empirical, shows how propeller thrust force derivative can be obtained and gives some additional information about misinterpretation of the propeller thrust effects that are present in the current literature. Findings New information about propeller thrust force contribution to airplane longitudinal stability analysis has been presented. This information should enable more precise insight in aircraft stability analysis and better understanding of the physical process that occurs during maneuver flight. Practical implications The information presented in this paper is new and specific to the propeller aircraft configuration. The methods used here are standard procedure to evaluating propeller thrust force derivative. Originality/value The information in this paper presents theoretical results. The method for calculating thrust force contribution to the airplane longitudinal stability is given depending on the propeller type and should enable good engineering results.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-09-27T02:47:38Z
      DOI: 10.1108/AEAT-04-2017-0104
       
  • Novel coupled model for power loss prediction in a world-record electric
           aircraft motor
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to devise an analytical approach to calculate conductor winding losses, considering multiple contributing aspects simultaneously. These include the geometric configuration of coil windings, frequency of the electric current and the dependency on the coil temperature, derived studying a coupled fluid–solid model considering the cooling system characteristics. The obtained results allow identifying power loss trends according to such system variables as coolant inlet temperature or overall flow rate of the motor. Design/methodology/approach An easy-to-use coupled analytical approach is applied, which is suitable for rapid estimations of the impact of parameter variation on the resulting conductor winding power losses that facilitates decision-making in the design process of electric aircraft engines. Findings In the considered cooling parameters, the overall conductor winding power losses vary approximately between 6 kW and 7.2 kW. More than 95 per cent of this loss is because of direct current losses. These losses cause the variation in maximal coil temperature ranging between 115°C and 170°C. Practical implications The SP260D motor is set and was currently tested in Extra 330. It recently broke two world records. Social implications One of the current trends in aircraft engineering is electric aircraft. Advantages of electric aircraft include improved manoeuvrability because of greater torque from electric motors, increased safety because of decreased chance of mechanical failure, less risk of explosion or fire in the event of a collision and less noise. There will be environmental and cost benefits associated with the elimination of dependency on fossil fuels and resultant emissions. Originality/value The use of a novel fluid–solid interaction model for predicting conductor winding power loss of the SP260D electric aircraft motor has not been done earlier. A novel alternative derivation of the widely applied Dowell’s formula (Dowell, 1966) is presented for the estimation of proximity losses in square winding conductors.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-09-27T02:44:38Z
      DOI: 10.1108/AEAT-12-2017-0278
       
  • Design optimization of helicopter rotor using kriging
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this study is to obtain optimum locations, peak deflection and chord of the twin trailing-edge flaps and optimum torsional stiffness of the helicopter rotor blade to minimize the vibration in the rotor hub with minimum requirement of flap control power. Design/methodology/approach Kriging metamodel with three-level five variable orthogonal array-based data points is used to decouple the optimization problem and actual aeroelastic analysis. Findings Some very good design solutions are obtained using this model. The best design point in minimizing vibration gives about 81 per cent reduction in the hub vibration with a penalization of increased flap power requirement, at normal cruise speed of rotor-craft flight. Practical implications One of the major challenges in the helicopters is the high vibration level in comparison with fixed wing aircraft. The reduction in vibration level in the helicopter improves passenger and crew comfort and reduces maintenance cost. Originality/value This paper presents design optimization of the helicopter rotor blade combining five design variables, such as the locations of twin trailing-edge flaps, peak deflection and flap chord and torsional stiffness of the rotor. Also, this study uses kriging metamodel to decouple the complex aeroelastic analysis and optimization problem.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-09-27T02:40:18Z
      DOI: 10.1108/AEAT-12-2016-0250
       
  • Unmanned aircraft automatic flight control algorithm in loop manoeuvre
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose This paper aims to present the idea of an automatic control system dedicated to small manned and unmanned aircraft performing manoeuvres other than those necessary to perform a so-called standard flight. The character of these manoeuvres and the range of aircraft flight parameter changes restrict application of standard control algorithms. In many cases, they also limit the possibility to acquire complete information about aircraft flight parameters. This paper analyses an alternative solution that can be applied in such cases. The loop manoeuvre, an element of aerobatic flight, was selected as a working example. Design/methodology/approach This paper used theoretical discussion and breakdowns to create basics for designing structures of control algorithms. A simplified analytical approach was then applied to tune regulators. Research results were verified in a series of computer-based software-in-the-loop rig test computer simulations. Findings The structure of the control system enabling aerobatic flight was found and the method for tuning regulators was also created. Practical implications The findings could be a foundation for autopilots working in non-conventional flight scenarios and automatic aircraft recovery systems. Originality/value This paper presents the author’s original approach to aircraft automated control where high precision control is not the priority and flight parameters cannot be precisely measured or determined.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-09-27T02:36:37Z
      DOI: 10.1108/AEAT-02-2018-0088
       
  • Multirotor UAV sensor fusion for precision landing
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose In relation to rapid development of possible applications of unmanned vehicles, new opportunities for their use are emerging. Among the most dynamic, we can distinguish package shipments, rescue and military applications, autonomous flights and unattended transportation. However, most of the UAV solutions have limitations related to their power supplies and the field of operation. Some of these restrictions can be overcome by implementing the cooperation between unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs). The purpose of this paper is to explore the problem of sensor fusion for autonomous landing of a UAV on the UGV by comparing the performance of precision landing algorithms using different sensor fusions to have precise and reliable information about the position and velocity. Design/methodology/approach The difficulties in this scenario, among others, are different coordination systems and necessity for sensor data from air and ground. The most suitable solution seems to be the use of widely available Global Navigational Satellite System (GNSS) receivers. Unfortunately, the position measurements obtained from cheap receivers are encumbered with errors when desiring precision. The different approaches are based on the usage of sensor fusion of Inertial Navigation System and image processing. However most of these systems are very vulnerable to lightning. Findings In this paper, methods based on an exchange of telemetry data and sensor fusion of GNSS, infrared markers detection and others are used. Different methods are compared. Originality/value The subject of sensor fusion and high-precision measurements in reference to the autonomous vehicle cooperation is very important because of the increasing popularity of these vehicles. The proposed solution is efficient to perform autonomous landing of UAV on the UGV.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-09-18T01:15:59Z
      DOI: 10.1108/AEAT-01-2018-0070
       
  • Interactive processing of radar target detection and tracking
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose An interactive processing scheme is proposed to improve the target detection probability as well as the tracking performance of the radar system. Design/methodology/approach Firstly, with the spatial-correlated features extracted from the foreground and background statistical models, the thresholds were adapted to distinguish the dim small targets from clutters in the complex incoherent radar images. Then, the target trajectories were constructed with the target tracking algorithm. According to the temporal correlation with the target life cycle, the thresholding values were modified in the neighbourhood of the predicted positions to improve the detection sensitivity in these areas during the tracking process. Finally, the temporal-correlated features of the remained clutters were used to further reduce the false alarm rate. Findings The proposed algorithm was applied on the simulated data, as well as the image sequences obtained with the incoherent marine radars. The detection results demonstrated that the interactive algorithm could detect and track the dim small targets with relatively low false alarm rate. Practical implications The interactive processing scheme could be applied for low-altitude airspace surveillance with incoherent marine radar. Originality/value The proposed scheme outperforms the classical radar target detection algorithms and the state-of-the-art image processing algorithms for video-based surveillance.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-09-13T12:56:52Z
      DOI: 10.1108/AEAT-07-2016-0115
       
  • The airbus A320 family fan cowl door safety modification: a human factors
           scenario analysis
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The Airbus A320 family engine fan cowl doors (FCDs) safety issue is known to the industry for almost 18 years; however, it has not been addressed adequately by the aircraft manufacturer and the various operators and regulating authorities. The purpose of this paper is to examine in a systematic way the possible operational and safety implications of a new modification on the engine FCDs. Design/methodology/approach An array of error-prone scenarios is presented and analysed under the prism of human factors in a non-exhaustive qualitative scenario analysis. Findings All examined scenarios are considered more or less probable. A number of accident prevention solutions are proposed for each of the scenario examined, in view of the acceptance and implementation of this modification by operators. Research limitations/implications As these scenarios are neither exhaustive nor have been tested/validated in actual aircraft maintenance practice, the further analysis is necessary. A substantial follow-up survey should take place, which should include a wider array of scenarios. This would allow obtaining the necessary data for a quantitative (statistical) analysis. Practical implications This case study identifies issues in relation to this modification, introduced by Airbus and the European Aviation Safety Agency (EASA), which may prove problematic from the point of view of safety effectiveness and disruption of operations. Originality/value This case study examines a long-standing aviation safety issue and the implications of a solution proposed by the aircraft manufacturer and adopted by EASA. This can be useful in increasing the awareness around these issues and highlight the importance of a human-centric and scenario-based design of engineering modifications towards minimising error in aircraft technical operations.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-09-13T12:48:27Z
      DOI: 10.1108/AEAT-08-2017-0191
       
  • Nanostructured copper-carbon nanotubes composites for aircraft
           applications
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The reliable performance of critical components working under extreme conditions is paramount to the safe operation of aircraft, and material selection is critical. Copper alloys are an obvious choice for such applications whenever a combination of transport, mechanical and tribological properties is required. However, low strength and hardness issues require development of new copper alloys and composites to improve service life and reliability. This study aims to investigate the effect of carbon nanotubes as reinforcement phase in copper-matrix composites. Design/methodology/approach The development of novel copper-based composites refined to the nanoscale was envisaged through mechanical milling of mixtures containing copper and carbon nanotubes (2 Wt.%). Milling took place in a planetary ball mill for times varying between 1 h and 16 h at 400 rpm. A ball-to-powder ratio of 20:1 and alumina vial and copper spheres were used under dry conditions or with addition of isopropyl alcohol. Scanning electron microscopy/energy dispersive spectroscopy, size distribution, Raman spectroscopy and X-ray diffraction were used to study the produced powders. Findings Attained results show that mechanical milling of the studied system produces nanostructured powders containing second-phase carbon nanotubes homogeneously distributed in the metallic matrix, together with severe copper grain refinement. This should correspond to increased residual microstresses, envisaging significant improvement of mechanical properties of the produced copper composites. Originality/value The novelty of the work resides in the use of carbon nanotubes for the reinforcement of copper, and on the systematic microstructural characterisation of the produced composites.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-09-12T02:50:12Z
      DOI: 10.1108/AEAT-01-2017-0016
       
  • Evaluation of discontinuities in friction stir welds of aluminum matrix
           composites
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to evaluate the welding quality of the friction stir joints of Al-SiC with diverse shape of pin geometry tools. Design/methodology/approach Aluminum matrix composites are gaining unlimited interest and special position in aeronautical industry because of their properties enhanced by the presence of ceramic reinforcement, such as lower density, dimensional stability, exceptional wear and abrasion resistance. Friction stir welding arises as a promising welding process with more advantages than traditional fusion process in the joining of aeronautical components with the utilization of a non-consumable rotational tool shaped by a shoulder and a pin, which can be designed in as many possible geometries. However, the welding quality is not always achieved when varying these pin configurations. Findings The fabrication and implementation of different pin geometry tools to weld the plates of the material allows to study the behavior of the joints assessing some discontinuities produced in the welds. Practical implications To examine the microstructural evolution and its behavior in the different zones of the joint, the practical implication consists in the use of different characterization techniques like the optic microscopy and scanning microscopy, furthermore mechanical test such as the measurement of hardness. Originality/value The study of the joints uses different welding tool geometries that were fabricated at prototype scale contribute in the microstructural analysis as well as in the evaluation of the possible discontinuities that are presented.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-09-07T12:57:33Z
      DOI: 10.1108/AEAT-01-2017-0024
       
  • Aerodynamics of plunging airfoil in wind gust
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose Growing application of micro aerial vehicle (MAV) sets in demand for accurate computations of low Reynolds number flows past their wings. The purpose of this study is to investigate the effect of unsteady freestream velocity or wind gust on a harmonically plunging symmetric NACA0012 airfoil at Re = 1,000. The influence of unsteady parameters, such as reduced frequency of plunging motion (0.25 < k < 1.5), non-dimensional plunging amplitude (ho = 0.2) and non-dimensional amplitude of wind gust (0.1 = λ = 0.4) has been studied. Design/methodology/approach Computations have been carried out using commercial software ANSYS Fluent 16.0. To incorporate the plunging motion, the entire reference frame is oscillating, and thereby, a source term is added in the Navier–Stokes equation. Findings The results have been presented in the form of streamlines, vorticity contours, lift and drag signals and their spectra. It is observed that the ratio of plunging frequency to gust frequency (f/fg) has strong influence on periodic characteristics of unsteady wake. It has also been observed that for a fixed plunging amplitude, an increase in value of k results into a change from positive drag to thrust. Practical implications The research has implications in the development of MAV. Originality/value This study is intended to get a better understanding of unsteady parameters associated with gusty flow in flapping wing applications and possible ways to alleviate its adverse effect on it.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-08-09T10:31:58Z
      DOI: 10.1108/AEAT-01-2017-0023
       
  • Aircraft piston engines on-condition exploitation
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose Currently, in many countries, aviation safety regulations allow piston engines exploitation above Time Between Overhaul (TBO) recommended by manufacturers. Upon fulfillment of certain requirements, which are already included in the manufacturers’ documentation, TBO extension is granted. National Aviation Authority has approved exploitation of piston engines to something like quasi on-condition maintenance, which has no technical proof behind. This leads to the conclusion that the current, simple way of the engine’s life extension is not the best solution for maintaining flight safety. Aircraft piston engines TBO extension requires changes in the current exploitation system. Design/methodology/approach The paper provides methodology for aircraft piston engines on-condition exploitation based on engine flight parameters (from cruise and takeoff) and engine oil particles analysis. The paper describes a method of diagnostic limits for certain engine parameters and elements in the oil assignation assuming that they come under rules of normal distribution. Findings It has been found that piston engines installed on maximum takeoff mass
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-06-13T08:09:03Z
      DOI: 10.1108/AEAT-01-2017-0042
       
  • Single engine turboprop aeroplane class in small air transport
    • Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose This paper aims to present the analysis of introduction of single engine turbo-prop aeroplane class in terms of certification specifications and flight crew licensing regulations. Design/methodology/approach Following the results of flight testing and additional performance and sizing calculations, the proposed class was placed among the existing aeroplane taxonomy in terms of performance, flight loads, mass penalty, fuel economy and several other factors. Concerning small air transport initiative, the new class was tried to be placed as a starting point in commercial pilot career. Findings The paper points the potential market for single engine turbopropeller aeroplanes and lists today obstacles in wider introduction. Therefore, remarks about required change of regulations and requirements for design process, as well as for crew licensing, are underlined. Practical implications The results of the study would be helpful in preliminary design of a new low-power turboprop aeroplane, as well as during tailoring the certification specifications. Originality/value The approach presented in this paper is a detailed extension of an original idea presented by author for the first time during Clean Sky/small air transport workshop.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-06-12T07:50:44Z
      DOI: 10.1108/AEAT-01-2017-0009
       
  • Properties of direct-quenched aircraft forged component made of
           ultrahigh-strength steel 300M
    • First page: 713
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose This paper aims to investigate the possibilities and determination of hot and warm forging of ultrahigh-strength steel 300M and subsequent quenching with accelerated air. Analysis of microstructure and mechanical properties of forged steel 300M focused on investigation of the effect of processing conditions on final properties, such as strength, impact strength and hardness, taking into consideration temperature gradients and within-part strain nonuniformity occurring in forging and direct cooling of aircraft landing gear. Design/methodology/approach The research involved semi-industrial physical modeling of hot deformation and direct cooling, aided with numerical analysis of both deformation and kinetics of phase transformations on cooling, with process conditions determined on the basis of numerical simulation of industrial process. Examination of forged and quench-tempered samples involved testing mechanical properties (tensile properties, hardness and impact strength) and microstructure. Findings Three major findings were arrived at: first, assessment of the effects of energy-saving method of cooling conducted directly after forging. Second, tensile properties, hardness and impact strength, were analyzed on the background of microstructure evolution during hot-forging and direct cooling; hence, applied temperature and cooling rates refer to actual condition of the material including varied deformation history. Third, the accelerated air cooling tests were carried out directly after forging with accurately measured and described cooling efficiency, which enabled the acquisition of data for heat treatment simulation with use of untypical cooling media. Research limitations/implications The conclusions formulated on the strenght of studies carried out in semi-industrial conditions with the use of model samples, despite strain and strain rate similarity, wait for full-scale verification in industrial conditions. The direct cooling tests carried out in semi-industrial conveyor Quenchtube are of cognitive value. Industrial realization of the process for the analyzed part calls for special construction of the cooling line and provision of higher cooling rate for heavy sections. Practical implications The results present microstructure properties’ relations for good-hardenability grade of steel, which is representative of several similar grades used in aircraft industry, which can support design of heat treatment (HT) cycles for similar parts, regardless of whether direct or conventional quenching is used. As they illustrate as-forged and direct-cooled microstructure and resultant mechanical properties, the studies concerning processing the steel of areas of lower temperature are transferable to warm forging processes of medium-carbon alloy steels. The geometry of the part analyzed in the case study is typical of landing gear of many aircrafts; hence, there is the high utility of the results and conclusions. Social implications The direct heat treatment technologies based on utilization of the heat attained in the part after forging allow significant energy savings, which besides cost-effectiveness go along with ecological considerations, especially in the light of CO2 emission reduction, improving economical balance and competitiveness. The presented results may encourage forgers to use direct cooling, making use of the heat attained in metal after hot forging, for applications to promote environmentally friendly heat treatment-related technologies. Originality/value Direct heat treatment typically seems to be reserved for micro alloyed steel grades and sections small enough for sufficient cooling rates. In this light, taking advantage of the heat attained in forged part for energy-saving method of cooling based on direct quenching as an alternative to traditional Q&T treatment used with application to relatively heavy sections is not common. Moreover, in case the warm-work range is reached in any portion of the forged part, effect of direct cooling on warm-forged material is addressed, which is a unique issue to be found in the related studies, whereas in addition to warm forging processes, the results can be transferable to coining, sizing or shot peening operations, where gradient of properties is expected.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-06-13T08:07:15Z
      DOI: 10.1108/AEAT-12-2015-0253
       
  • Fatigue life prediction of ceramic-matrix composites
    • First page: 720
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose This paper aims to predict fatigue life and fatigue limit of fiber-reinforced ceramic-matrix composites (CMCs) with different fiber preforms, i.e. unidirectional, cross-ply, 2D-, 2.5D- and 3D-woven, at room and elevated temperatures. Design/methodology/approach Under cyclic loading, matrix multicracking and interface debonding occur upon first loading to fatigue peak stress, and the interface wear appears with increasing cycle number, leading to degradation of the interface shear stress and fibers strength. The relationships between fibers fracture, cycle number, fatigue peak stress and interface wear damage mechanism have been established based on the global load sharing (GLS) criterion. The evolution of fibers broken fraction versus cycle number curves of fiber-reinforced CMCs at room and elevated temperatures have been obtained. Findings The predicted fatigue life S–N curve can be divided into two regions, i.e. the Region I controlled by the degradation of interface shear stress and fibers strength and the Region II controlled by the degradation of fibers strength. Practical/implications The proposed approach can be used to predict the fatigue life and fatigue limit of unidirectional, cross-ply, 2D-, 2.5D- and 3D-woven CMCs under cyclic loading. Originality/value The fatigue damage mechanisms and fibers failure model were combined together to predict the fatigue life and fatigue limit of fiber-reinforced CMCs with different fiber preforms.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-06-07T10:19:49Z
      DOI: 10.1108/AEAT-01-2016-0014
       
  • Trajectory optimization of a multi-tethered space robot on large spinning
           net structures
    • First page: 727
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to investigate the time optimal trajectory of the multi-tethered robot (MTR) on a large spinning net structures in microgravity environment. Design/methodology/approach The MTR is a small space robot that uses several tethers attached to the corner-fixed satellites of a spinning net platform. The transition of the MTR from a start point to any arbitrary designated points on the platform surface can be achieved by controlling the tethers’ length and tension simultaneously. Numerical analysis of trajectory optimization problem for the MTR is implemented using the pseudospectral (PS) method. Findings The globally time optimal trajectory for MTR on a free-end spinning net platform can be obtained through the PS method. Research limitations/implications The analysis in this paper is limited to a planar trajectory and the effects caused by attitude of the MTR will be neglected. To make the problem simple and to see the feasibility in the general case, in this paper, it is assumed there are no any limitations of mechanical hardware constraints such as the velocity limitation of the robot and tether length changing constraint, while only geometrical constraints are considered. Practical implications The optimal solution derived from numerical analysis can be used for a path planning, guidance and navigation control. This method can be used for more efficient on-orbit autonomous self-assembly system or extravehicular activities supports which using a tether-controlled robot. Originality/value This approach for a locomotion mechanism has the capability to solve problems of conventional crawling type robots on a loose net in microgravity.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-06-07T08:37:58Z
      DOI: 10.1108/AEAT-05-2015-0141
       
  • Spacecraft localization by indirect linear measurements from a single
           antenna
    • First page: 734
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to present a two-stage approach for estimation of spacecraft’s position and velocity by indirect linear measurements from a single antenna. Design/methodology/approach In the first stage, direct nonlinear antenna measurements are transformed to linear x-y-z coordinate measurements of spacecraft’s position, and statistical characteristics of orbit determination errors are analyzed. Variances of orbit parameters’ errors are chosen as the accuracy criteria. In the second stage, the outputs of the first stage are improved by the designed Extended Kalman Filter for estimation of the spacecraft’s position and velocity on indirect linear x-y-z measurements. Findings The complex content of the measurement matrix in the conventional method causes periodic singularities in simulation results. In addition, the convergence of the filter using direct measurements is highly dependent on the initialization parameters’ values due to the nonlinear partial derivatives in the Jacobian measurement matrix. The comparison of the accuracy of both methods shows that the estimation by using indirect measurements reduces the absolute estimation errors. The simulation results show that the proposed two-stage procedure performs both with better estimation accuracy and better convergence characteristics. The method based on indirect measurements provides an unnoticeably short transient duration. Practical implications The proposed method can be recommended for satellite orbit estimation regarding its presented superiorities. Originality/value Inputting the single antenna measurements to the filter indirectly results in a quite simpler measurement matrix. As a result, the convergence of the filter is faster and estimation errors are lower.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-06-19T12:23:10Z
      DOI: 10.1108/AEAT-12-2015-0245
       
  • Optimal wingtip device design for transport airplane
    • First page: 743
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The present work aims to analyze the feasibility of wingtip device incorporation into transport airplane configurations considering many aspects such as performance, cost and environmental impact. A design framework encompassing optimization for wing-body configurations with and without winglets is described and application examples are presented and discussed. Design/methodology/approach modeFrontier, an object-oriented optimization design framework, was used to perform optimization tasks of configurations with wingtip devices. A full potential code with viscous effects correction was used to calculate the aerodynamic characteristics of the fuselage–wing–winglet configuration. MATLAB® was also used to perform some computations and was easily integrated into the modeFrontier frameworks. CFD analyses of transport airplanes configurations were also performed with Fluent and CFD++ codes. Findings Winglet provides considerable aerodynamic benefits regarding similar wings without winglets. Drag coefficient reduction in the order of 15 drag counts was achieved in the cruise condition. Winglet also provides a small boost in the clean-wing maximum lift coefficient. In addition, less fuel burn means fewer emissions and contributes toward preserving the environment. Practical implications More efficient transport airplanes, presenting considerable lower fuel burn. Social implications Among other contributions, wingtip devices reduce fuel burn, engine emissions and contribute to a longer engine lifespan, reducing direct operating costs. This way, they are in tune with a greener world. Originality/value The paper provides valuable wind-tunnel data of several winglet configurations, an impact of the incorporation of winglets on airplane design diagram and a direct comparison of two optimizations, one performed with winglets in the configuration and the other without winglets. These simulations showed that their Pareto fronts are clearly apart from each other, with the one from the configuration with winglets placed well above the other without winglets. The present simulations indicate that there are always aerodynamic benefits present regardless the skeptical statements of some engineers. that a well-designed wing does not need any winglet.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-08-13T02:24:47Z
      DOI: 10.1108/AEAT-07-2015-0183
       
  • Aircraft neural modeling and parameter estimation using neural partial
           differentiation
    • First page: 764
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to build a neural model of an aircraft from flight data and online estimation of the aerodynamic derivatives from established neural model. Design/methodology/approach A neural model capable of predicting generalized force and moment coefficients of an aircraft using measured motion and control variable is used to extract aerodynamic derivatives. The use of neural partial differentiation (NPD) method to the multi-input-multi-output (MIMO) aircraft system for the online estimation of aerodynamic parameters from flight data is extended. Findings The estimation of aerodynamic derivatives of rigid and flexible aircrafts is treated separately. In the case of rigid aircraft, longitudinal and lateral-directional derivatives are estimated from flight data. Whereas simulated data are used for a flexible aircraft in the absence of its flight data. The unknown frequencies of structural modes of flexible aircraft are also identified as part of estimation problem in addition to the stability and control derivatives. The estimated results are compared with the parameter estimates obtained from output error method. The validity of estimates has been checked by the model validation method, wherein the estimated model response is matched with the flight data that are not used for estimating the derivatives. Research limitations/implications Compared to the Delta and Zero methods of neural networks for parameter estimation, the NPD method has an additional advantage of providing the direct theoretical insight into the statistical information (standard deviation and relative standard deviation) of estimates from noisy data. The NPD method does not require the initial value of estimates, but it requires a priori information about the model structure of aircraft dynamics to extract the flight stability and control parameters. In the case of aircraft with a high degree of flexibility, aircraft dynamics may contain many parameters that are required to be estimated. Thus, NPD seems to be a more appropriate method for the flexible aircraft parameter estimation, as it has potential to estimate most of the parameters without having the issue of convergence. Originality/value This paper highlights the application of NPD for MIMO aircraft system; previously it was used only for multi-input and single-output system for extraction of parameters. The neural modeling and application of NPD approach to the MIMO aircraft system facilitate to the design of neural network-based adaptive flight control system. Some interesting results of parameter estimation of flexible aircraft are also presented from established neural model using simulated data as a novelty. This gives more value addition to analyzing the flight data of flexible aircraft as it is a challenging problem in parameter estimation of flexible aircraft.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-08-13T02:26:26Z
      DOI: 10.1108/AEAT-02-2016-0021
       
  • Performance monitoring and analysis of various parameters for a small UAV
           turbojet engine
    • First page: 779
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose This paper aims to discuss engine health monitoring for unmanned aerial vehicles. It is intended to make consistent predictions about the future status of the engine performance parameters by using their current states. Design/methodology/approach The aim is to minimize risks before they turn into problems. In accordance with these objectives, temporal and financial savings are planned to be achieved by contributing processes such as extending the engine life, preventing early disassembly-reassembly and mechanical wears and reducing the maintenance costs. Based on this point of view, a data-based software is developed in MATLAB (Matrix Laboratory) program for the so-called process. Findings The software is operated for the performance parameters of the turbojet engine that is used in a small unmanned aerial vehicle of Tusas Engine Industry. The obtained results are compared with the real data of the engine. As a result of this comparison, a fault that may occur in the engine can be detected before being determined. Originality/value It is clearly demonstrated that the engine operation in adverse conditions can be prevented. This situation means that the software developed operates successfully.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-06-19T12:25:50Z
      DOI: 10.1108/AEAT-02-2016-0024
       
  • Design of the composite casing of microstrip antenna for the aerospace
           satellite
    • First page: 788
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The paper aims to present a design and numerical verification procedure of a composite casing of a microstrip antenna for an aerospace satellite. Design/methodology/approach The casing for the microstrip antenna was designed in a form of a laminate shell with variable number of layers of reinforcing fabric. The material properties, both static and dynamic, were determined experimentally and then exported to an environment of numerical analyses. The numerical modal analysis allows optimizing the geometry and lay-up of the casing in such a way that a number of modal shapes occurring in the operational frequency band was significantly reduced, several modal shapes with high displacement in flanges of the casing were eliminated and the values of natural frequencies were increased. A final model of the composite casing was subjected to two types of analyses which simulate typical operation conditions during spacecraft mission. These analyses contained thermomechanical quasi-static analyses with 12 loadcases and thermomechanical shock analyses with 9 loadcases, which simulate various mechanical and temperature conditions. Findings Results of the performed analyses were compared with safety margins determined by following requirements to spacecraft vehicles. The obtained results confirm the design feasibility, which allow considering the proposed design during manufacturing of a prototype in further studies. Practical implications Moreover, the presented results can be considered as a design methodology guideline, which can be helpful for engineers working in the aerospace industry. Originality/value The originality of the paper lies in the proposed design and verification procedure of composite elements subjected to operational loading during a spacecraft mission.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-06-28T10:06:40Z
      DOI: 10.1108/AEAT-11-2016-0226
       
  • Trajectory planning for mini unmanned helicopter in obstacle and windy
           environments
    • First page: 806
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose Obstacle and wind field are common environmental factors for mini unmanned helicopter (MUH) flight. This paper aims to develop a trajectory planning approach guiding MUH to avoid static and dynamic obstacles and to fly in steady uniform or boundary-layer wind field. Design/methodology/approach An optimal control model including a nonlinear flight dynamics model and a cubic obstacle model is established for MUH trajectory planning. Radau pseudospectral method is used to generate the optimal trajectory. Findings The approach can plan reasonable obstacle-avoiding trajectories in obstacle and windy environments. The simulation results show that high-speed wind fields increase the flight time and fluctuation of control inputs. If boundary-layer wind field exists, the trajectory deforms significantly and gets closer to the ground to escape from the strong wind. Originality/value The key innovations in this paper include a cubic obstacle model which is straightforward and practical for trajectory planning and MUH trajectory planning in steady uniform wind field and boundary-layer wind field. This study provides an efficient solution to the trajectory planning for MUH in obstacle and windy environments.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-07-04T08:35:39Z
      DOI: 10.1108/AEAT-05-2016-0080
       
  • Modelling and hovering control for a coaxial unmanned helicopter using
           sliding mode
    • First page: 815
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose To facilitate the nonlinear controller design, dynamic model of a novel coaxial unmanned helicopter (UH) is established and its coupling analysis is presented. Design/methodology/approach The chattering-free sliding mode controller (SMC) with unidirectional auxiliary surfaces (UASs) is designed and implemented for the coaxial ducted fan UH. Findings The coupling analysis based on the established model show severe coupling between channels. For coaxial UH’s special model structure, UAS-SMC controller is proposed to reduce the coupling characteristics between channels of the UH by setting controllers’ output calculation sequence. Originality/value The flight control law and control logic are successfully tested in numerical simulation and hardware in the loop (HIL) simulation. The results show best hovering performances without chattering problem, even under the bounded internal dynamics and external disturbances.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-07-02T01:23:21Z
      DOI: 10.1108/AEAT-05-2016-0075
       
  • A method to analyze and optimize hybrid electric architectures applied to
           unmanned aerial vehicles
    • First page: 828
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose This paper addressed some critical issues in the development of hybrid electric powertrains for aircraft and propose a design methodology based on multi-objective optimization algorithms and mission-based simulations. Design/methodology/approach Scalable models were used for the main components of the powertrain, namely, the (two stroke diesel) engine, the (lithium) batteries and the (permanent magnet) motor. The optimization was performed with the NSGA-II genetic algorithm coupled with an in-house MATLAB tool. The input parameters were the size of engine, the hybridization degree and the specification of the battery (typology, nominal capacity, bus voltage, etc.). The outputs were electric endurance, additional volume, performance parameters and fuel consumption over a specified mission. Findings Electric endurance was below 30 min in the two test cases (unmanned aerial vehicles [UAVs]) but, thanks to the recharging of the batteries on-board, the total electric time was higher. Fuel consumption was very high for the largest UAV, while an improvement of 11 per cent with respect to a conventional configuration was obtained for the smallest one. Research limitations/implications The research used a simplified approach for flight mechanics. Some components were not sized in the proposed test cases. Practical implications The results of the test cases stressed the importance of improving energy density and power density of the electric path. Social implications The proposed methodology is aimed at minimizing the environmental impact of aircraft. Originality/value The proposed methodology was obtained from the automotive field with several original contributions to account for the aircraft application.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-06-19T12:21:22Z
      DOI: 10.1108/AEAT-11-2016-0202
       
  • Vision-based relative navigation using cubature Huber-based filtering
    • First page: 843
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose A novel vision-based relative navigation system (VBRNS) plays an important role in aeronautics and astronautics fields, and the filter is the core of VBRNS. However, most of the existing filtering algorithms used in VBRNS are derived based on Gaussian assumption and disregard the non-Gaussianity of VBRNS. Therefore, a novel robust filtering named as cubature Huber-based filtering (CHF) is proposed and applied to VBRNS to improve the navigation accuracy in non-Gaussian noise case. Design/methodology/approach Under the Bayesian filter framework, the third-degree cubature rule is used to compute the cubature points which are propagated through state equation, and then the predicted mean and the associated covariance are taken. A combined minimum l1 and l2-norm estimation method referred as Huber’s criterion is used to design the measurement update. After that, the vision-based relative navigation model is presented and the CHF is used to integrate the line-of-sight measurements from vision camera with inertial measurement of the follower to estimate the precise relative position, velocity and attitude between two unmanned aerial vehicles. During the design of relative navigation filter, the quaternions are used to represent the attitude and the generalized Rodrigues parameters are used to represent the attitude error. The simulation is conducted to demonstrate the effectiveness of the algorithm. Findings By this means, the VBRNS could perform better than traditional VBRNS whose filter is designed by Gaussian filtering algorithms. And the simulation results demonstrate that the CHF could exhibit robustness when the system is non-Gaussian. Moreover, the CHF has more accurate estimation and faster rate of convergence than extended Kalman Filtering (EKF) in face of inaccurate initial conditions. Originality/value A novel robust nonlinear filtering algorithm named as CHF is proposed and applied to VBRNS based on cubature Kalman filtering (CKF) and Huber’s technique. The CHF could adapt to the non-Gaussian system effectively and perform better than traditional Gaussian filtering such as EKF.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-07-04T08:37:17Z
      DOI: 10.1108/AEAT-01-2017-0006
       
  • Digitalization of aircraft performance nomograms
    • First page: 851
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to develop a new tool for aircraft performance analysis and optimization. Design/methodology/approach In this paper, the methodology of converting nomogram curves into mathematical functions is presented. Aircraft performance nomograms represent graphical interpretation of influence of several variables on performance such as environmental conditions, runway conditions and aircraft mass. The aircraft performance nomograms are converted in mathematical functions that describe several independent variables’ influence on aircraft performance parameters. To achieve greater accuracy in calculation of aircraft performance parameters, it is necessary to determine mathematical functions presented by dependent variable variations with several independent variables. The method of determining mathematical functions is illustrated on Fokker 100 landing gear extended net climb gradient determination graph. Findings To evaluate model, it was necessary to determine net climb gradient both graphically and analytically using model and compare the results. After solving both analytically and graphically, it was concluded that results are a match. During model evaluation, it was observed that model has a lot of advantages such as it has great precision of calculation, requires less time to calculate results and has minimum error possibility. Practical implications Final result of digitalization of aircraft performance nomograms is software production. The usage of this software can reduce flight planning and aircraft exploitation costs in several different manners. Airliners can produce such a software for those types of aircraft where there is no software provided from aircraft manufacturer. Originality/value Digitalization of aircraft performance nomogram has never been analyzed before, although there is a possibility of this particular methodology implementation in a practical manner in aviation industry.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-07-06T08:10:14Z
      DOI: 10.1108/AEAT-05-2016-0070
       
  • Autopilot design for an aircraft by using Luenberger observer design
    • First page: 858
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this paper is to design linear quadratic regulator (LQR) based Luenberger observer for the estimation of unknown states of aircraft. Design/methodology/approach In this paper, the LQR-based Luenberger observer is deliberated for autonomous level flight of unmanned aerial vehicle (UAV) which has been attained productively. Various modes like phugoid and roll modes are exploited for controlling the rates of UAV. The Luenberger observer is exploited for estimation of the mysterious states of the system. The rates of roll, yaw and pitch are used as an input to the observer, while the remaining states such as velocities and angles have been anticipated. The main advantage of using Luenberger observer was to reduce the cost of the system which has been achieved lucratively. The Luenberger observer proposes sturdiness at the rate of completion to conquest over the turmoil and insecurities to overcome the privileged recital. The FlightGear simulator is exploited for the endorsement of the recital of the Luenberger observer-based autopilot. The level flight has been subjugated lucratively and has been legitimated by exploiting the FlightGear simulator. The authenticated and the validated results are offered in this paper. Microsoft Visual Studio has been engaged as a medium between the MATLAB and FlightGear Simulator. Findings The suggested observer based on LQR ensures the lucrative approximation of the unknown states of the system as well as the successful level flight of the system. The Luenberger observer is used for approximation of states while LQR is used as controller. Originality/value In this research work, not only the estimation of unknown states of both longitudinal and lateral model is made but also the level flight is achieved by using those estimated states and the autopilot is validated by using the FlightGear, while in most of the research work only the estimation is made of only longitudinal or lateral model.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-08-02T11:01:24Z
      DOI: 10.1108/AEAT-11-2016-0224
       
  • Simulation of dynamic stall using direct-forcing immersed boundary method
           at low Reynolds number
    • First page: 869
      Abstract: Aircraft Engineering and Aerospace Technology, Ahead of Print.
      Purpose The purpose of this study is simulation of dynamic stall behavior around the Eppler 387 airfoil in the low Reynolds number flow with a direct-forcing immersed boundary (DFIB) numerical model. Design/methodology/approach A ray-casting method is used to define the airfoil geometry. The governing continuity and Navier–Stokes momentum equations and boundary conditions are solved using the DFIB method. Findings The purposed method is validated against numerical results from alternative schemes and experimental data on static and oscillating airfoil. A base flow regime and different vortices patterns are observed, in accordance with other previously published investigations. Also, the effects of the reduced frequency, the pitch oscillation amplitude and the Reynolds number are studied. The results show that the reduced frequency has a major effect on the flow field and the force coefficients of the airfoil. On the other hand, the Reynolds number of the flow has a little effect on the dynamic stall characteristics of the airfoil at least in the laminar range. Practical implications It is demonstrated that the DFIB model provides an accurate representation of dynamic stall phenomenon. Originality/value The results show that the dynamic stall behavior around the Eppler 387 is different than the general dynamic stall behavior understanding in the shedding phase.
      Citation: Aircraft Engineering and Aerospace Technology
      PubDate: 2018-08-02T11:04:24Z
      DOI: 10.1108/AEAT-05-2017-0128
       
 
 
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