ECCM15 - 15 TH EUROPEAN CONFERENCE ON COMPOSITE MATERIALS, Venice, Italy, 24-28 June 2012 1 PRODUCTION AND MECHANICAL TESTING OF AN UNMANNED HELICOPTER TAIL CONE Deniz Kavrar 1, a , M. Lütfi Öveçoğlu 1, b , Halit S. Türkmen 2, c 1 Istanbul Technical University, Faculty of Chemistry and Metallurgy, Metallurgical and Materials Engineering Department, Maslak, Istanbul, 34469, Turkey 2 Istanbul Technical University, Faculty of Aeronautics and Astronautics, Aeronautical Engineering Department, Maslak, Istanbul, 34469, Turkey * a d_kavrar@hotmail.com, b ovecoglu@itu.edu.tr, c halit@itu.edu.tr Keywords: Tail cone, carbon/epoxy composite, laminated shell, composite manufacturing, bending. Abstract One of the important structural parts of helicopters is tail cone which connects the tail rotor to the front structure which includes the main rotor. The tail rotor is an important part of a helicopter and is used to counter the torque effect created by the main rotor. Therefore, the tail cones are subjected to flexural and torsional moments. Because of the long distance between the main rotor and tail rotor, the lightweight materials such as composites are often used for the tail cones. In this study the tail cone is produced using carbon/epoxy face sheets and honeycomb core using a wet hand lay-up technique. The vacuum is applied during the production at elevated temperature. The tail cone is tested under bending and a combined loading including bending and torsion. The test of tail cone is also modeled using the finite element method. The experimental and numerical results are compared. The results are presented and discussed. 1 Introduction Carbon fiber reinforced advanced composite materials are being used for several structural applications because of their mechanical properties, including high strength-to-weight and stiffness-to-weight ratios. The aerospace industry was among the first to realize the benefits of composite materials. Airplanes, rockets, and missiles all fly higher, faster, and farther with the help of composites [1]. One of the uses of these materials is for the tail cone of helicopters. The tail cones are the structures connecting the tail rotor to the fuselage. It is mainly subjected to the pitching moment and torsion. Because it is long to obtain the enough distance between the tail rotor and the main rotor, the materials used for manufacturing the tail cone need to be light [2]. Tail cone must provide structural support for the tail rotor, the fin and the tail plane, as well as having some aerodynamic characteristics. The cone has to be high set and slim to give clearance for the rear loading. The tail cone effectively couples two masses together; the main rotor and the tail rotor. These will each experience both static and dynamic forces. The main rotor will apply vibrations to the hull, but the tail rotor will tend to the lag behind because of its mass and it will result in stress on the tail cone. Whirling forces from the main rotor will rock the hull side to side. Helicopter tail cone must be resistant to bending and torsion [3].