Purpose The purpose of this paper is to present application of multidisciplinary design optimisation (MDO) in redesign of a small composite aircraft. The redesign process was integration of the turboprop engine in a small composite aircraft. The process requires cooperation of specialists from many disciplines and definition of their tasks. For selected tasks, the authors present results of the calculation. Design/methodology/approach The authors used collaborative optimisation (CO) algorithm to solve the problem. They decomposed this complex process into a set of tasks in different engineering/research disciplines and used techniques and methods specific for each task (research/engineering discipline) to find a proper solution. The computer-aided design (CAD), computational fluid dynamics (CFD) and computational structural mechanics (CSM) commercial software were used as common tools as well as intentionally developed computer programmes were used as basic tools in some tasks, in particular, for aerodynamic optimisation, calculation of load and stability of aircraft. The exchange of data between separate tasks allowed achieving the main goal of complex design process. Findings Selected optimisation algorithm, CO, proved efficient for the authors’ purposes. The effectiveness of multidisciplinary optimisation depends as much on organisational parameters as it does on technical and technology parameters. Practical implications Multidisciplinary optimisation needs to be an integral part of analysis and design process. The successful optimisation results allowed to meet the requirements and to proceed to the next phase of work – preparing technical documentation for manufacturing the components necessary for integration of the airplane with the new engine. Originality/value Presented results of design process are a valuable example of how to achieve the final goal in an ongoing project.

Conceptual and preliminary designs of future aircraft have become increasingly complex due to the enlargement of the basic criteria for evaluating emerging solutions. In the past, the basic performance characteristics of an airplane were the only selection criteria. Today, more and more emphasis is placed on factors such as impact on the environment, cost-effectiveness, or comfort of travel. The method for optimization of the key parameters of a small aircraft for use in the initial phase of a project is presented in this paper. It takes into account the requirements of aviation safety imposed by the European Union certification specifications CS-23 and requirements of aircraft competitiveness. Requirements and design assumptions were formulated based on the concept of the Small Air Transport system (SATs). The method is based on the multidisciplinary design optimization and covers the basic areas related to the design of aircraft: aerodynamics, aircraft structure, performance and expected operating costs. The objective function is defined as the value of the direct operating cost per passenger-kilometre. An evolutionary algorithm was applied to solve the optimization problem. As an example of the use of this method, the optimization of design parameters of the two classes of aircraft, 9-seater and 19-seater was carried out. The results were compared with the parameters of aircraft, which are in service. Sensitivity analysis of the objective function with respect to selected parameters of the aircraft was also made. The analysis allowed to select the most important parameters responsible for the operational costs.

Over the last few years, teams from several research centres have been working on the concept of Small Air Transport, filling the niche between a regular surface transport and a scheduled air transport-on the distances over 200 km, utilizing numerous, though low in volume, passengers' streams-giving regions a chance to improve their communication capabilities. Small Air Transport's tasks are performed on small aeroplanes, which take up to 19 passengers, with a flight time of up to 4 h and at a reasonable price for a mass recipient. An important feature of the Small Air Transport system is personalization, which is flexible adaptation of the transport process to the customer's requirements and capabilities. This paper focuses on the selection and optimization of key parameters of aircraft fleet used in Small Air Transport. The research and analysis were based on the parameters of a reference aircraft selected for each individual class of small aircraft. Taking into account the data of currently used aircraft, the calculations were made to obtain the generalized transport costs per passenger kilometre. The generalized transport costs covers both-the total operating costs and value of time of passengers. As a result of minimizing these costs in terms of the variability of the key design factors of aircraft, the parameters of the recommended aircraft, in particular, classes were obtained. It was found that generalized passenger-kilometre costs for recommended Small Air Transport aircraft are only 20-30% higher than for regional aircraft (with the same load factor) and are more advantageous for Small Air Transport aircraft (lower cost) for small local passenger flows. Utilizing Small Air Transport aircraft, the profitability of air transport expands to significantly less intense passenger flows. The analysis allowed defining key design parameters of aircraft fleet in Small Air Transport in the initial phase of a project.

Το πρώτο κεφάλαιο παρουσιάζει τους 'μακαρισμούς' ως πρότυπο της ηθικής συμπεριφοράς των 'δια Χριστόν σαλών'. Αναλύονται οι έννοιες 'Μωρία' και 'σαλότητα' και η μεταξύ τους σχέση στην Παράδοση της Εκκλησίας. Το δεύτερο ασχολείται με την οριοθέτηση των χαρακτηριστικών των 'σαλών' και με τη χριστομίμητη ταπείνωσή τους. Το τρίτο κεφάλαιο εξετάζει το θέμα του σκανδάλου, της αυτοταπείνωσης και του εμπαιγμού του κόσμου στη ζωή των 'σαλών'. Το τέταρτο ασχολείται με την κλήση στην άσκηση της 'σαλότητας' με το σκοπό στον οποίο απέβλεπαν οι 'σαλοί' και με τη θέση τους στη ζωή της Εκκλησίας. Το πέμπτο εξετάζει το ήθος των ΄σαλών', οι οποίοι δια της ταπεινώσεώς τους και της αποταγής του κόσμου γεύθηκαν την εν Χριστώ ελευθερία και την άπειρη αγάπη του Θεού.