Considerations on all composite UAV structures: critical analisys and new proposals

This paper will introduce some consideration about the use of composite structures for the Unmanned Aerial Vehicles, and the main problems about the use of this type of construction will be analysed starting from my last direct experience. These considerations derive from the last activities in progress at the Department of Aeronautical Engineering of University of Naples, and in particular with the Aeronautical Construction Group directed from Prof. A. Accardo. During last years, experience has been acquired with the realization of a small advanced composite unmanned aircraft named "Federica". The phases followed for the design and the construction of this vehicle have been the same of those normally followed for a standard aircraft of the general aviation: Mission configuration options, Wind tunnel tests, Choice of material, Loads structural, Preliminary sizing, Performance determination, Structural design and test (CAD, FEM), Constructive plans of single parts, Systems definition, Single parts construction, Static tests, Acquisition and installation of the propulsion system, Assemblage, Systems installation and setup, Flight tests organization and realization, Post processing of data acquired during flight and theoretical model validation. Today, after about 2 year of flight tests, this vehicle is able to perform a limited surveillance mission and it has onboard about 30 sensors for on-flight data acquisition. On the basis of the experience gained and according to the necessity to operate with such systems in safe conditions, the design of a new larger UAV is currently in progress. Waiting the official start of new project (about the end of 2004) we have prepared the version B of Federica and it will be ready to fly before the end of July. In this version a lot of new solutions will be tested before of their definitive application in our new larger UAV. Departing from a synthetical description of these projects, we will make a critical analysis on these technologies; in particular we will underline the problems concerning the "hybrid" links (composite/aluminium) and the solutions from us adopted in the last projects.