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A conceptual design method for composite material stiffened panels used in aircraft tail structures and unmanned aircraft has been developed to bear compression and shear loads.

The method is based on classical laminated theory to fulfil the requirement of building a fast design tool, necessary for this preliminary stage. The design criterion is local and global buckling happen at the same time. In addition, it is considered that the panel does not fail due to crippling, stiffeners column buckling or other manufacturing restrictions. The final geometry is determined by minimising the area and, consequently, the weight of the panel.

The results obtained are compared with a classical method for sizing stiffened panels in aluminium. The weight prediction is validated by weight reductions in aircraft structures when comparing composite and aluminium alloys.

The work is framed in conceptual design field, so hypotheses like material or stiffeners geometry shall be taken a priori. These hypotheses can be modified if it is necessary, but even so, the methodology continues being applicable.

The procedure presented in this paper allows designers to know composite structure weight of aircraft tails in commercial aviation or any lifting surface in unmanned aircraft field, even for unconventional configurations, in early stages of the design, which is an aid for them.

The contribution of this paper is the development of a new rapid methodology for conceptual design of composite panels and the feasible application to aircraft tails and also to unmanned aircraft.

The purpose of this study of which this work is only the first part, is the development of conceptual design tools to perform an optimized design of the rear fuselage and tail surfaces. The development of a new and extensive database of transport aircraft and an analysis of certain general, rear fuselage and horizontal stabilizer parameters of the aircraft are presented in this paper.

In addition to the development of a comprehensive high accurate database, linear and non-linear correlations between different parameters of the aircraft have been established. Data were analyzed using comparison criteria between aircraft database based on the mission, the number of engines installed or arrangement of the tail surfaces.

It has been possible to obtain very relevant, linear and non-linear correlations for critical design parameters to optimize the design of the rear fuselage and horizontal tail.

In the case of the tail cone, the data have not yielded significant correlations. On the other hand, there are some regressions that do not work well in some cases and for which it would be good to further expand the database.

Results obtained greatly improve the existing methods for conceptual design, which usually pay no attention to the rear part of the aircraft. Besides, these new procedures are adapted to different categories of aircraft, allowing greater optimization of the designs.

The novel contribution of this work is focused on the development of a new high-fidelity database and includes many more aircraft than any other work previously released. Also, new correlations, linear and non-linear, additional parameters not considered in previous studies, and differentiated by category of aircraft studies are provided.