ISBN 978-3-8439-1163-4

978-3-8439-1163-4, Reihe Luftfahrt

Mihaela Florentina Niță
Contributions to Aircraft Preliminary Design and Optimization

297 Seiten, Dissertation Polytechnische Universität Bukarest (2012), Softcover, A5

Zusammenfassung / Abstract

This work covers two related fields a) aircraft preliminary design and optimization, including aircraft cabin design and optimization and b) optimization of engineering working processes in cabin design and refurbishing. For a) existing equations or methods for aircraft Preliminary Sizing and Conceptual Design are adjusted and new equations or methods are introduced (e.g. equation for Oswald factor, method for winglets efficiency estimation, method for estimating overhead stowage volume). Equations were combined to an Aircraft Design methodology. The methodology was implemented into Microsoft Excel to create a tool called OPerA – Optimization in Preliminary Aircraft Design. Optimization was initially done with the commercial optimization software, Optimus. A technique called Differential Evolution was selected to be programmed in VBA and integrated into OPerA. Four objective functions are selected: minimizing of Direct Operating Costs (DOC) represented by equivalent ton-miles costs, minimizing fuel mass, minimizing maximum take-off mass and maximizing of a composed objective function DOC+AV consisting of a weighting of DOC and Added Values, which are selected parameters responsible for additional revenues for an airline. For b) three alternatives are proposed to increase efficiency of cabin design activities: i) a partitioning algorithm delivers the sequence that minimizes information feedback, ii) the analysis of the eigenstructure of the matrix of processes underlines those with the greatest influence on the engineering system, and iii) a cross impact analysis identifies groups of processes belonging to five spheres: reactive, dynamic, impulsive, low impact and neutral. The selected reference aircraft for optimization is Airbus A320-200. A maximum number of 20 variables are optimized for the standard version and three other versions (braced wings, natural laminar flow and both at the same time). Varying requirements together with aircraft and cabin parameters and adding the two innovations delivered these improvements: reduced DOC by about 16 %, maximum take-off mass by 24 %, fuel mass by 50 % and increased DOC+AV by 48 %. The tool provided is an efficient Aircraft Design tool, producing traceable optimizations in Preliminary Aircraft Design. Optimizing process chains for cabin redesign activities is not only beneficial, but also helps demonstrating required design and certification capabilities to aeronautical authorities.