Preliminary design of a very large PrandlPlane freighter and airport network analysis

The present work is a study on a large freighter aircraft with the aim to improve the competitiveness of the airfreight with respect to the other means of transport. The PrandtlPlane configuration is conveniently applied to very large aircraft and, in this paper, the design of a freighter of 24 intermodal containers is chosen as a significant example of application. The maximum range of this big freighter is 3.000 miles. The first part of the paper is dedicated to the optimization of the aircraft configuration, using a homemade optimization code; the objective function is the aerodynamic efficiency with constraints regarding the stability of flight. A set of different local minima are determined, corresponding to solutions that satisfy all the constraints imposed and the absolute minimum is chosen inside this set on the basis of further conditions on structural aspects. The solutions include PrandtlPlanes in which a third lifting surface is considered in addition to the configuration. The preliminary design is completed by the evaluation of both the low speed and the flight dynamics characteristics with a sizing of low speed devices and control surfaces. The range limitation is accomplished by the definition of a set of freight airports to be positioned properly worldwide; a mathematical theory has been formulated in order to optimize the positions of these dedicated airports on the basis of economical parameters; some examples are shown in the second part of the thesis.