The contemporary debate on the need for the civil aeronautical industry to reconcile its global warming impact and the continuous air traffic growth is gaining in prominence. While solutions exist to tackle different aspects of this complex problem individually, the core of the response lies in rethinking the conventional aeroplane architecture in order to reach new energy efficiency optima. This paper presents a function-to-form framework used for describing different aspects of architectural design of an aeroplane as technological system. Firstly, a brief overview of different existing ways to improve aeroplane architectures is given. With that background, a preliminary definition of multi-level system composition of an aeroplane is presented. A physics-based framework is then correlated to the Functional, Behavioural, Structural and Experiential requirement framework, in order to characterise the different physical phenomena experienced by an aeroplane for a single operating point. These provide basis for definition of a qualitative Figure of merit dubbed Integration Potential of an architecture, which serves as proxy for describing function-to-form mapping of aeroplane system architectures. Using both the historical, contemporary and projected tendencies of aeroplane technology advances, existence of an asymptotic limit of this parameter is inferred. This limit arguably indicates the extent to which it could still be possible to go in search for energy efficiency gains by virtue of system architecture design. @en

This paper presents a simple explanatory framework to analyse the diverse strategies proposed by the civil aviation sector in attempts to reconcile its growth tendencies with its impact on natural environment. Despite framing the industry as a single entity that has a problem to solve, it is better represented as a diverse set of actors, each responsible for various constituent systems at different phases of their respective life cycles. To elucidate this multi-actor pursuit of higher-level emergent objectives, the paper firstly presents an overview of different development scenarios dedicated to guide the industry towards sustainability. Given that the constituent systems tackled in such strategies strongly depend on each other, the sustainability objective relies on reconciling all the different agendas and contributions in unison, making them collectively compatible with the dynamics of the socio-economic and the natural world. To analyse the problem coherently, a basic description of an arbitrary system as a coarse-grained closed causal network is formulated. A categorisation for the model parameters is proposed to help define the system boundary and interaction with the environment unambiguously, dispensing with the need to know details of the model that represents the system at hand. This formalism was previously derived for preliminary sizing and performance estimation of aeroplane engines; by virtue of recursive nature of the coarse-graining process, the same formalism can be used to describe systems at any arbitrary levels, which enables a small system (in the current paper the system of interest being the propulsive system) to be integrated into a multi-level causal dependence framework. Then, the typical industry evolution scenarios are re-framed on the common ground of the causal network formalism. Subsequently, the framework is extended with a simple quantitative energy-based representation to formulate a qualitative case of how the scenarios could be formulated more coherently to avoid conflicting local optimisation objectives in pursuit of common higher-level goals. Finally, the entirety of the presented elements are brought together in a proposal to conceptualise an industrial system as a life cycle which exchanges matter, energy and information with its large-scale environment. The paper argues that such framing of the problem can pave the way to simplification of the problem of conflicting high-level objectives, by enabling a coherent understanding of the mutual dependence between a system of interest and the much more complex system of systems that is the aeronautical industry.@en

An overwhelming abundance of innovative civil aeroplane concepts has been presented by the research community in recent decades. Their development has been motivated mainly by need for better operating energy, or in particular the fuel efficiency - the common objective variable for economic and environmental optimisation. This paper focuses on one common conceptual issue with the disruptive concepts which originates in remarkable divergence of the concept space in different directions away from the conventional Tube&Wing paradigm. As a consequence, it becomes increasingly difficult to make a meaningful comparison of any arbitrary pair of concepts by employing the conventional intuitions, definitions, or figures of merit. The objective of the paper is to elaborate a framework that could encompass the entire design space under a common conceptual umbrella. The method we employ relies on systems engineering principles of Function-to-Form mapping. Firstly, a comprehensive review of innovative concepts is provided, with emphasis on the problem of the apparent complexity of the design space arising from the conventional taxonomic intuitions. Then, the descriptive framework is presented, with relevant definitions of function, form and system architecture. First-order application of the framework to the conventional aeroplane design space implies that the Tube&Wing concept family can be represented as roughly one-to-one function-to-form mapping. By analysing the summarised pool of disruptive concepts in the same key, inference is made on existence of an extensive and continuous design space. Furthermore, and argument is presented for existence of the civil-aeroplane performance optimisation trend that aligns with parts of the design space moving away from one-to-one function-to-form mapping. In other words, parts of the design space moving towards the regions in which concepts map as many functions onto as few forms as possible. If extended to the entirety of the life cycle of the system, this framework could reveal even more possibilities for system optimisation, in line with contemporary socio-economic attempts to resolve potentially contradictory requirements and constraints of sustainable growth of the aeronautical industry.@en

This paper presents development of an innovative method for aeroplane system architecture design, based on the principles of causal networks. In light of the environmental crisis that the world faces, it is argued that the new design method should be motivated by sustainability values in the first place. This implies the necessity for a method that is evolvable, as well as for the design artefact to include an awareness of its contribution to dynamics of the higher-level systems within which it is embedded. To that end, the method is based on gradual and iterative development of an initial abstract object which represents relevant system functions over a designated life cycle. The architecture design procedure consists in evolving this abstract object by means of the pre-defined design rules towards a material architectures that satisfies multiple requirements and constraints for multiple actors. The design rules at hand represent a combination of quantitative methods such as first principles of physics and qualitative principles of systems engineering. In complement to system characteristics, rigorous book-keeping of matter and energy interfaces with the object’s surroundings is at the core of the method. To test the developed principles with the elementary method development at hand, a propulsive system architecture case study is elaborated. The case study represents a simple case of a short-medium range engine architecture designed to respond to operating requirements, whose resulting performance is book-kept and evaluated in a much broader context than the operation (in-flight performance), for which engines are commonly preliminary-designed.@en