Multi-role fighter aircraft are facilitated by operational and platform capabilities that are in turn supported by basic aircraft function. Thermal management (TM) is a basic aircraft function. Effective TM design at the aircraft concept stage can determine if it can support the intended operational and aircraft capabilities early in the aircraft project. In this study, a three-session workshop with a cross-functional team for TM design was conducted at Saab AB. The outcomes from the workshop resulted in a framework for a detailed understanding of the steps to be carried out iteratively for TM design by a cross-functional team. It also provides the dependencies for these steps and the various functional groups that need to be involved in each step. The steps can be used to iterate TM design at the aircraft concept stage and understand the implications on aircraft and operational capabilities. Further, the workshop methodology presented can be used to obtain similar frameworks for design of other basic functions at the aircraft concept stage.

Surveillance aircraft perform long-duration missions (>eight hours) that include detection and identification of objects on the ground, the water, or in the air. They have surveillance systems that require large amounts of cooling power (typically 10 s of kW) for long durations. For aircraft application, vapor cycle systems (VCS) are emerging as a more efficient alternative to conventional cooling systems. In this study, a two-part method was applied to a cooling system with a VCS that can be installed on a surveillance aircraft. The first part focused on a parameter tuning study set-up and demonstrated how after identifying the operating conditions, constraints, and requirements, the only cooling system parameter available for tuning was the VCS compressor speed. The second part focused on a modelling and solving strategy for the cooling system and showed how the capacity of an aircraft cooling system was impacted by tuning the VCS compressor speed (Hz) for a surveillance system heat flow rate from 10 kW to 70 kW. The results from this study can be used to design a control strategy for the compressor. In a broader perspective, the two-part method and the results analysis presented can serve as a preliminary method for aircraft VCS control optimization studies.

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 paper shows how simulation-based optimization can be used to investigate the impact of technologydevelopment on the feasibility and performance of electric aircraft. This work investigates the design of anelectric/hydrogen-powered commuter aircraft (certified according to CS/FAR23) based on a dynamic missionsimulation including a 6DOF flight dynamics aircraft model. The electric/hydrogen hybrid propulsion system isbeing optimized to realize a design missions of 500km and 1000km, respectively, based on present technologylevels with a scenario with technology improvement of batteries and fuel cells. By the optimization-basedsizing of the propulsion train components, automated morphological and topological changes on the propulsionsystem are realized. The results cover a spectrum from pure electric to pure hydrogen fuel cell aircraft includingall possible hybrid solutions in between. In this way, simulation-based optimization is demonstrated also for itsuse for concept selection and system architecture optimization.

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.