PRELIMINARY WING OPTIMIZATION FOR VERY LARGE TRANSPORT AIRCRAFT WITH WINGSPAN CONSTRAINTS

Airbus has designed its A380 wing within the ICAO 80-m span limit, resulting in a relatively low aspect ratio: 7.53. The objective of the research described in this paper is to determine the economical and environmental consequences of this decision since the span limit is not an FAA requirement and may thus be exceeded. Using an updated version of a parametric design model two types of optimization have been performed. After verification of the accuracy of the model, within the first type of optimization the aspect ratio A has been varied for fixed wing area, payload- range specifications and cruise altitude (10,668 m). A reduction of 2.4% in direct operating costs (DOC) and 11% in Global Warming Parameter (GWP) could be achieved by applying A = 9.9 (wingspan b = 91.5 m). Within the second type of optimization, starting from a specified set of thrust loading - wing loading combinations, aspect ratio A and cruise altitude h have been varied simultaneously. Choosing the DOC optimum as a design point would result in A = 8.9 (b=86.7 m) and h = 9,022 m but the gain in DOC with respect to A = 9.9 and h = 10,668 m would be virtually negligible. In order to both comply with the 80-m wingspan limit (on the ground) and benefit from the higher aspect ratio, a folding wingtip system (FWS) has been implemented in the model. The DOC-optimum A would again be 9.9 (for h = 10,668 m) yielding a reduction of 2.1% in DOC and 10.3% in GWP relative to the baseline (A = 7.53). SYMBOLS