In the field of System-of-Systems (SoS) engineering, the study of interactions between complex systems froma holistic point of view is important for finding emerging behaviours. To observe as many behaviours aspossible, especially when field testing is not a viable option, simulations play an important role in design spaceexploration and formulation for the Firefighting SoS framework. The presented work describes an AgentBased Model (ABM) approach for simulation of wildfire spread and its detection using collaborating vehicles:Unmanned Aerial Vehicles (UAVs), or partly autonomous air- and land-based vehicles. Implemented in theopen-source software NetLogo, the usage of its Geographic Information System (GIS) extension allows tosimulate scenarios at specific locations. This ABM will be used in the future for Agent-Based Simulations(ABS) for the study of an SoS framework oriented to firefighting, including design and optimization of the SoS,constituent systems and their subsystems.

Studying Systems of Systems (SoS) in relation to Measures of Effectiveness (MoE) is a difficult task. This is due to that SoSs include several system levels and operate in changing environments. There are also computational challenges related to modeling and simulation of SoSs and it is difficult to predict behaviors. Therefore, choosing model fidelity for system models and assessing their impact on MoE is of high relevance to the field. This paper illustrates an approach to modeling and simulation for SoSs that can be used to assess the impact of scenario parameters and to explore when level of fidelity on system level affects the MoE. This is made through a case study based on Search and Rescue (SAR) operations where a Design Of Experiments (DOE) of scenario parameters is performed and simulations of each scenario experiment is performed. The case study shows how Agent Based Simulations (ABS) can be used to obtain the MoE for different SAR missions and how the choice of model fidelity for one of the aircraft’s sensors has different effects for various scenarios. Additionally, a Visual Analytics (VA) approach is introduced and used to create a dashboard for visualizing the obtained simulation results in an interactive way. This allows users to make explorations on the resulting data and see how different scenarios influence the performance of each SoS. Furthermore, the results show that changes in scenario parameters impacts the MoE and that this is difficult to predict, at least using a quantitative method. The results point to the importance of exploration for both the scenario, using an interactive dashboard, but also to the importance of exploring the simulation model to study emerging phenomenon. The results of this approach have raised questions regarding if a more qualitative approach of studying SoSs could be beneficial to study MoE for SoSs and if inspiration could be transferred from a more scientific point of view of systems.

This work illustrates how a proposed method can be used to create optimization frameworks for early conceptual design studies and to increase overall knowledge at an early design stage. The method is intended to facilitate concept selection in challenging domains that typically involve multidisciplinary design problems with contradictory requirements. The main focus of the work presented here is on the conceptual design of helicopters; however, the method is intended to be applicable to early design studies in other domains as well. In short, statistics about existing helicopters are collected and compiled to provide a basis for various regression analyses. The purpose of this is to unravel relationships in the data and to obtain simple estimation models from statistical regressions that can be used in conjunction with existing formulas and equations to generate an initial helicopter design estimate. Models for each discipline, such as aerodynamics, are then created using the outcomes of the regression analyses and existing equations. Lastly, the method is used to define a multidisciplinary design optimization framework incorporating all the models obtained from the different disciplines. A case study based on search and rescue operations is used to test the proposed framework in order to obtain possible first suggestions for the baseline design of a new general-purpose search and rescue helicopter.

Aerospace systems are connected with the operational environment and other systems in general. The focus in aerospace product development is consequently shifting from a singular system perspective to a System-of-Systems (SoS) perspective. This increasing complexity gives rise to new levels of uncertainty that must be understood and managed to produce aerospace solutions for an ever-changing future. This paper presents an approach to using architecture frameworks, and ontologies with description logic reasoning capabilities, to break down SoS needs into required capabilities and functions. The intention of this approach is to provide a consistent way of obtaining the functions to be realized in order to meet the overarching capabilities and needs of an SoS. The breakdown with an architecture framework results in an initial design space representation of functions to be performed. The captured knowledge is then represented in an ontology with description logic reasoning capabilities, which provides a more flexible way to expand and process the initial design space representation obtained from the architecture framework. The proposed approach is ultimately tested in a search and rescue case study, partly based on the operations of the Swedish Maritime Administration. The results show that it is possible to break down SoS needs in a consistent way and that ontology with description logic reasoning can be used to process the captured knowledge to both expand and reduce an available design space representation.

This paper presents and analyses the research front on development methodologies that can be applied to flight simulations for development purposes. This field includes any flight simulator used during the development phase of an aircraft, when flight test or other validation data is still scarce. A review of the literature published between 1999-2019 is performed. As flight-specific literature on the topic is limited, a broader view on flight simulators is adopted. Simulators are regarded as risk-averse scientific software; that is, software created to understand a phenomenon and whose primary goal is to be correct. This perspective highlights the lack of suitable established software development methodologies (SwDev) for this software type. Two solutions to this problem have been identified: one treating scientific SwDev as a knowledge acquisition process, and another one treating it as development of enabling systems, following the established product development processes. These solutions need to be completed with methodologies to deal with the multidisciplinarity of the flight simulation problem, such as model exchange standards or workflows for multidisciplinary collaboration.

This study presents a solution for connecting system simulation and aircraft concept development using solely open standards. An easy-to-use optimisation framework for aircraft concept development is created with the help of the Modelica, Functional Mock-up Interface (FMI), and System Structure and Parameterization (SSP) standards, and the open source tools OpenModelica and OMSimulator. The framework allows for conceptual aircraft design accounting for transient phenomena by means of standardised integration of dynamic simulation models of aircraft subsystems. The framework is applied to an industry-relevant use case concerning the concept development of a generic fighter aircraft. The generality and modularity of the framework and its straightforward implementation enables tailoring of the optimisation goals to the user needs and requirements. The adoption of industry-wide standards allows for the inclusion of system simulation models developed in the modelling tool best suited for each discipline, thus integrating dynamic system simulation already at the aircraft conceptual design stage.

This paper presents a method for generating a design space intended for aircraft design with the use of ontologies. Aircraft design, seen from a System-of-Systems (SoS) perspective, gives an idea of the complicated relationships and complexities that need to be managed and understood to develop suitable systems for an ever-changing future. Holistic SoS analyzes are used to investigate customer and stakeholder needs that then can be broken down into capabilities and subsequently functions to be performed by involved Constituent Systems (CS), sub-systems and system elements. Ontologies with description logic reasoning capabilities are then used to represent the outcome of the breakdown. An ontology development and integration process can afterwards be used to merge different ontologies together and by that map the derived functions to means that can implement them. This results in an available SoS design space that can be further processed using a description logic reasoner. The outcome of the proposed method is a reduced available design space of functions to be performed and their respective design alternatives. Search and Rescue (SAR) operations based on the Swedish Maritime Administration (SMA) are used as a case study to test the proposed method and to illustrate how it can be utilized. At the end, a design space of alternatives for a new type of search aircraft is generated with ontology and description logic reasoning.

System-of-Systems Engineering (SoSE) has become a constantly growing field within product development for complex systems. Systems are becoming more and more connected with other systems and the operational environment in general. This takes the development process to new levels of complexity where high degrees of uncertainties are expected due to ever occurring changes in the operational environment, and other external factors such as politics, economy, and technology. This creates a need of being able to understand the influence of changes early in the development process and to facilitate the systems? perseverance. The focus of the development shifts from fulfilling specific requirements, to being able to meet needs and deliver capabilities over time. Additionally, modeling and simulation for complex systems and System-of-Systems (SoS) becomes a valued alternative to the economically prohibited and almost impossible prototype testing. In consideration of this problem, the presented work introduces a method for both modeling and simulation of a SoS. The method uses ontology with description logic reasoning to derive and narrow down a SoS design space which is further analyzed using Agent Based Simulation (ABS). A Search and Rescue (SAR) scenario is used as a case study to test the method. Measures of Effectiveness (MoE), based on the time it takes to find a rescue subject and the cost of doing so, are used to evaluate the SoS performances. The presented method is envisioned to be used early in the development of complex systems and SoS to increase the overall understanding of them.

Following the electrification of the automotive sector, the idea of electric-powered flight for commercial air transportation is becoming, in the eye of the public, the main hope for greener air transportation. To what extent can electric aircraft reduce the energy and environmental footprint of aviation? How should they look like and how does their operation compare to conventional jet aircraft? What technologies are needed, and which of them are already in place? This paper analyses critically some of the unresolved challenges that lay ahead. Current commercial operations are examined and short-term effects of electrification are identified. Fundamental components, basic design and operating concepts are analysed to highlight unavoidable constraints that seem often overlooked. It becomes clear that electric propulsion alone will not fully meet society’s expectations even if key enabling technologies develop as forecasted. Nevertheless, this paper suggests that electrification may instead become one piece of a propulsion-technology mix that would address more effectively our short- and long-term goals.

The decades-old idea of electric-powered commercial flight has re-emerged along with high expectations for greener air transportation. To what extent can electric aircraft reduce the energy and environmental footprint of aviation? How should they look like and how does their operation compare to conventional jet aircraft? What technologies are needed, and which of them are already in place? This paper goes back to basics and analyses critically some of the unresolved challenges that lay ahead. Current commercial operations are examined and the short-term effects of electrification are identified. Fundamental components, basic design and operating concepts are analysed to highlight unavoidable constraints that seem often overlooked. These limitations are illustrated with a conceptual study of a full-electric FAR/CS-23 commuter and realistic estimations of its performance. It becomes clear that electric propulsion alone will not fulfil the expected goals, but it might be one more step on the way.

Product development, especially in aerospace, has become more and more interconnected with its operational environment. In a constant changing world, the operational environment will be subjected to changes during the life cycle of the product. The operational environment will be affected by not only technical and non-technical perturbations, but also economical, managerial and regulatory decisions, thus requiring a more global product development approach. One way to try tackling such complex and intertwined problem advocates studying the envisioned product or system in the context of system of systems (SoS) engineering. SoSs are all around us, probably in any field of engineering, ranging from integrated transport systems, public infrastructure systems to modern homes equipped with sensors and smart appliances; from cities filling with autonomous vehicle to defence systems. Since also aerospace systems are certainly affected, this work will present a holistic approach to aerospace product development that tries spanning from needs to technology assessment. The proposed approach will be presented and analysed and key enablers and future research directions will be highlighted from an interdisciplinary point of view. Consideration of the surrounding world will require to look beyond classical engineering disciplines.

This paper presents an approach to system-of-systems engineering for product development with the use of ontology. A proposed method for building as well as using ontology to generate and explore system-of-systems design spaces based on identified system-of-system needs is presented. The method is largely built to cover the first levels of related work, where a process for system of systems in the context of product development is introduced. Within this work, it is shown that scenarios for a system-of-systems can be used to identify needs and subsequently the system-of-systems capabilities that fulfils them. The allocation of capabilities to possible constituent systems is used to show the available design space. The proposed method of this paper therefore addresses these initial challenges and provides a framework for approaching the system-of-systems design space creation using ontology. A case study is used to test the method on a fictitious search and rescue scenario based on available resources and information from the Swedish Maritime Administration. The case study shows that a representation of a system-of-systems scenario can be created in an ontology using the method. The ontology provides a representation of the involved entities from the fictitious scenario and their existing relationships. Defined ontology classes containing conditions are used to represent the identified needs for the system-of-systems. The invocation of a description logic reasoner is subsequently used to classify and create an inferred ontology where the available system-of-systems solutions are represented as sub-classes and individuals of the defined classes representing the needs. Finally, several classes representing different possible system-of-systems needs are used to explore the available design space and to identify the most persistent solutions of the case study.

Purpose This paper aims to present the newly founded Swedish Aeronautical Research Center (SARC), based on the triple helix theory, to foster the seamless Swedish aerospace research interplay between academia, research organizations and industry. Design/methodology/approach The paper is a technical paper, mainly relating and explaining sources and concepts for research planning and organization. Used concepts are the triple helix approach (for socioeconomic effects), the role of academia and industry interplay for education and the technology readiness level (TRL) concept for strategic research planning. Focusing on the establishment of a graduate school, lessons learned from previous national research schools are also presented. Findings The paper gives an overview of and explains the interplay between politics, social welfare and industrial Ramp;D needs, with the academic viewpoint of aeronautical research and education. Shortcomings in both the use of TRL for research program planning and the Swedish competence cluster system are identified and remedies suggested. The main findings are suggestions for future actions to be conducted by SARC in the fields of research and education. Originality/value So far, no publication about the newly founded SARC has been made yet. It is unique in the way that it makes substantial use of national technical documents so that this information becomes available for non-Swedish speakers. Additionally, the perhaps-unique system of industrial competence clusters is presented.

Modern aircraft can be seen as heterogeneous systems, containing multiple embedded subsystems which are in today’s simulations split into different domain-specific models based on different modelling methods and tools. This paper addresses typical workflow-driven model integration problems with respect to model fidelity, accuracy in combination with the selected abstraction methods and the target system characteristics. A short overview of integration strategies with the help of co-simulation frameworks including an analysis of the inherent problems that emerge because of different domain-specific modelling methods is being given. It is shown that huge benefits can be reached with the help of a smart system break-up. In detail, the discrepancy between the cyber-physical system simulations and human-machine interaction (HMI) models are being analysed. Therefore, a close look at the typical shortcomings of behavioural models is being discussed, too. To enable an effort-less human-in-the-loop integration into a cyber-physical system simulation, the usage of flight simulation software, offering real-time capability and a graphical user interface is suggested. This approach is applied to overcome today’s complexity and shortcomings in human psychological models. An example implementation based on a commercial flight simulator software (X-Plane) together with a high-performance system simulation tool (Hopsan) via UDP communication is presented and analysed.

Purpose This paper aims to present a knowledge-based fuel system, implementation and application, oriented towards its use in aircraft conceptual design. Design/methodology/approach Methodology and software tools oriented to knowledge-based engineering applications (MOKA) is used as a foundation for the implementation and integration of fuel systems. Findings Including fuel systems earlier in the design process creates an opportunity to optimize it and obtain better solutions by allocating suitable locations in an aircraft, thereby reflecting on the centre of gravity of the aircraft. Research limitations/implications All geometries are symbolic, representing a space allocation inside the aircraft for the fuel system. A realistic representation of the real components could be realized in detail design. Practical implications Fuel weight is a significant part of take-off weight and decisive in aircraft sizing and range estimations. The three-dimensional geometry provides a better estimation of the volume that is available to allocate the necessary entities. It also provides fast measures for weight and balance, fuel capacity, relative tank positions and a first estimation of piping length. Originality/value Fuel systems appear early in the design process, as they are involved in several first estimations. By using a knowledge-based engineering approach, several alternatives can be visualized and estimated in the conceptual design process. Furthermore, using the weights and centre of gravity at different angles of pitch and roll of each fuel tank, the aircraft could be optimized for handling qualities by using automatically generated system simulation models.

"The conceptual design is the early stage of aircraft design process where results are needed fast, both analytically and visually so that the design can be analyzed and eventually improved in the initial phases. Although there is no necessity for a CAD model from the very beginning of the design process, it can be an added advantage to have the model to get the impression and appearance. Furthermore, this means that a seamless transition into preliminary design is achieved since the CAD model can guardedly be made more detailed. For this purpose, knowledge-based aircraft conceptual design applications Tango (Matlab) and RAPID (CATIA) are being developed at Linköping University. Based on a parametric data definition in XML, this approach allows for a full 3D CAD integration. The one-database approach, also explored by many research organizations, enables the flexible and efficient integration of the different multidisciplinary processes during the whole conceptual design phase. This paper describes the knowledge-based design automated methodology of RAPID, data processing between RAPID and Tango and its application in the courses ‘‘Aircraft conceptual design’’ and ‘‘Aircraft project course’’ at Linköping University. A multifaceted user interface is developed to assist the whole design process."

Aircraft Conceptual Design (ACD) is facing new challenges on the way to enhanced fidelity level required of the nowadays complex system design. Namely the integration of models and simulations of different fidelity levels to enhance the analysis capability while maintaining a streamlined, transparent, and low cost working process is required.

In this thesis, the use of object-oriented Knowledge-Based Engineering (KBE) methods to enable an early integration of simulation models within the ACD phase are presented. Careful investigations of modelling and simulation approaches of multi-domain systems are carried out before, and their use in the ACD phase is examined regarding the efficiency between spend effort and result in accuracy. Enabling the named topics, a central, parametric information model approach is presented. By the extended use of XML, XSD and XSLT, domain-specific models can be translated from this dataset, supporting a direct CAD and automated simulations integration.

Modelling systems as graph networks is a simple approach for unified modelling within the conceptual design stage. Based on this theory, the similarity of different modelling approaches like Dependency Structure Matrix (DSM), MDDSM, or Channel-Agency Networks is shown. Using object-oriented programming, all these and more aspects such as e.g. Fault Tree Analysis (FTA) can be globally handled as one graph set.

Based on the outcomes of the theoretical part, the development of a ACD framework is described. Backed by a central XML-based namespace, this framework integrates a complete CAD environment to ensure an appropriate environment for the geometric domain modelling. Furthermore, the use of KBE for automated simulation model integration is exemplified by a whole aircraft simulation including the hydraulic aircraft flight control system (FCS).

Current research on subscale flight testing methodologies at Linköping University is performed by using various platforms, some of them with advanced configurations. These have been previously flown in open-loop under direct commands from the pilot. However, the interest in flying some of these platforms with relaxed stability and the investigation of multi-surface control allocation techniques motivated the implementation of a simple low-cost flight control system based on commercial-off-the-shelf components. The work described in this paper evaluates the simplest available solutions that provide control augmentation for small, longitudinally unstable, free-flying models. This work also tries to define a reliable, fail-safe system architecture that can be implemented in more advanced platforms. Moreover, data acquisition and analysis are evaluated with the aim of applying system identification techniques.

Future combat aircraft inherently conceal all the components internally essentially for stealth reasons. The geometry is optimized for subsonic and supersonic flight area distribution and the components and payload to be fitted inside the aircraft. The basic requirements to accomplish are fuel consumption, mission profile, and military performance. Analytical methods comprise of a quick aerodynamic and structural optimization. The result obtained is then compared with multi-fidelity aero-structural analysis

Model management during conceptual aircraftdesign is an important issue. This paper showsthe basic ideas and capabilities of the conceptualaircraft design framework developed atLinköping University with focus on efficient lowfidelity geometry definition. As an example, theanalysis of an F-16 fighter is presented.

A new fighter aircraft will most likely be acollaborative project. In this study conceptualknowledge-based design is demonstrated, usingmodels of comparable fidelity for sizing, geometrydesign, aerodynamic analysis and system simulationfor aircraft conceptual design. A newgeneration fighter is likely to involve advancedcontrol concept where an assessment of feasibilitythrough simulation is needed already atthe conceptual stage. This co-design leads to adeeper understanding of the trade-offs involved.In this paper a study for a future combat aircraftis made. Conceptual knowledge-based design isdemonstrated by optimizing for a design mission,including a super-cruise segment.

This paper looks at fuel consumption due to shaft power off-takes from the engine and the related increase in the aircraft’s fuel consumption. It presents a review and comparison of published and unpublished data on this kind of consumption. The paper presents results from the TURBOMATCH engine simulation model, calibrated to real world engine data. A generic equation is derived for the calculation of fuel consumption due to shaft power extraction. Main result is the shaft power factor k_P found to be in the order of 0.002 N/W for a typical cruise flight. This yields an amazingly high efficiency for power generation by shaft power extraction from a turbo fan engine of more than 70 %.

This paper describes the XML basedmultidisciplinary tool integration in aconceptual aircraft design framework,developed by the Division of Fluid andMechatronic Systems (FluMeS), LinköpingUniversity. Based on a parametric datadefinition in XML, this approach allows for afull 3D CAD integration. The one-databaseapproach, also conducted by many researchorganizations, enables the flexible and efficientintegration of the different multidisciplinaryprocesses during the whole conceptual designphase. This central database approach with adetailed explanation of the developed geometrydescription and the data processing, focusing onthe CAD integration is presented. Applicationexamples of the framework are presentedshowing the data build up and data handling.

This paper describes the methodology of generating simulation models out of basic information, available during conceptual design phase. The implementation of an aircraft system is shown as an example using the simulation software HOPSAN.

Because of the limited direct project-related data available at the conceptual stage, the traditional method of creating physical simulation models by the bottom up approach with the help of (standard) component libraries is not applicable. Instead, the respective systems’ architecture as well as their composition has to be descriptively predefined in a flexible, wide-range applicable manner, known as the knowledge base (KB) approach. These system technology driven design declarations – combined with project related data – result in roughly pre-tuned system simulation models, which may help when conducting more detailed investigations of the project such as performance analysis.

This (system architecture) knowledge-based approach is shown on the whole aircraft system level down to the detailed implementation of the control surface actuator systems of the primary flight control system.

Aircraft design is an inherently multidisciplinary activity that requires integrating different models and tools to reach a well-balanced and optimized product. At Linköping University a design framework is being developed to support the initial design space exploration and the conceptual design phase. Main characteristics of the framework are its flexible database in XML format, together with close integration of automated CAD and other tools, which allows the developed geometry to be directly used in the subsequent preliminary design phase. In particular, the aim of the proposed work is to test the framework by designing, optimizing and studying a transport aircraft wing with respect to aerodynamic, geometry, structural and accessability constraints. The project will provide an initial assessment of the capability of the framework, both in terms of processing speed and accuracy of the results.

This paper describes the development of a scalable simulation model of a bleed-less, fully electric Environmental Control System (ECS). The focus during development of the model was on fast execution speed and system architecture in order to enable optimization algorithms for system efficiency optimization to be constructed. Classical sensitivity and robustness analysis were used during model development. ECS architecture functionality and reliability has been proven for different flight mission working conditions as well as different failure modes. For this purpose, an analysis tool related to the simulation model and active simulation model control was developed.

This paper presents the development of a design framework for the initial conceptual design phase. The focus in this project is on a flexible database in XML format, together with close integration of automated CAD, and other tools, which allows the developed geometry to be used directly in the subsequent preliminary design phase. The database and the geometry are also described and an overview is given of included tools like aerodynamic analysis and weight estimation.

Purpose - The purpose of this paper is to present the latest subscale demonstrator aircraft developed at Linkoping University. It has been built as part of a study initiated by the Swedish Material Board (FMV) on a Generic Future Fighter aircraft. The paper will cover different aspects of the performed work: from paper study realised by SAAB to the first flight of the scaled demonstrator. The intention of the paper is to describe what has been realised and explain how the work is may be used to fit within aircraft conceptual design. Design/methodology/approach - The approach has been to address the challenges proposed by the customer of the demonstrator, how to design, manufacture and operate a scaled demonstrator of an aircraft study in conceptual design within five months. Similar research projects have been reviewed in order to perform the current work. Findings - The results obtained so far have led to new questions. In particular, the project indicated that more research is needed within the area of subscale flight testing for usage in aircraft conceptual design, since a scaled demonstrator is likely to answer some questions but will probably open up new ones. Research limitations/implications - The current research is just in its infancy and does not bring any final conclusion but does, however, offer several guidelines for future works. Since the aircraft study was an early phase concept study, not much data are available for validation or comparison. Therefore, the paper is not presenting new methods or general conclusions. Practical implications - Results from a conceptual aircraft study and a realisation of a scaled prototype are presented, which show that scaled flight testing may be used with some restriction in conceptual design. Originality/value - The value of this paper is to show that universities can be involved in prototype development and can work in close collaboration with industries to address issues and solutions within aircraft conceptual design.

A suitable method for simulating large complex dynamic systems is represented by distributed modelling using transmission line elements. The method is applicable to all physical systems, such as mechanical, electrical and pneumatics, but is particularly well suited to simulate systems where wave propagation is an important issue, for instance hydraulic systems. By using this method, components can be numerically isolated from each other, which provide highly robust numerical properties. It also enables the use of multi-core architecture since a system model can be composed by distributed simulations of subsystems on different processor cores.

Technologies based on transmission lines has successfully been implemented in the HOPSAN simulation package, develop at Linköping University. Currently, the next generation of HOPSAN is developed using an object-oriented approach. The work is focused on compatibility, execution speed and real-time simulation in order to facilitate hardware-in-the-loop applications. This paper presents the work progress and some possible features in the new version of the HOPSAN simulation package.

At Linkoping University aeronautical research is focusing on design methodologies in early stages of aircraft design. Rapid design and evaluation of prototypes is considered an important branch of this work. In this paper flight test activities at the university are described, the design of a light weight affordable data acquisition system is explained and some flight test results including flow visualization are presented.