АНАЛІЗ КОНСТРУКТИВНО-ТЕХНОЛОГІЧНИХ ОСОБЛИВОСТЕЙ ХВОСТОВИХ БАЛОК ВЕРТОЛЬОТІВ ТРАНСПОРТНОЇ КАТЕГОРІЇ
Authors: Гребеніков О. Г. , Орловський М. М. , Костанді В. М. 
Published: June 2024

An analysis of the structural and technological features of the design of the tail beam of transport category helicopters was carried out. The main zones of probable fatigue failure of the tail girders were determined. Based on the analysis of the structural and technological features of the design of tail beams of transport category helicopters, the tail beam design of the physical model was developed. In the practice of world helicopter industry, single-screw helicopters, which are characterized by relative simplicity of design, control system and relatively low cost, have become the most widespread. The tail beam is the most complex part in the production of a helicopter. For a single-screw helicopter, the tail beam is a very critical part of the structure, the failure of which, in most cases, leads to an aviation incident. Ensuring strength requirements is an extremely important task; therefore it is regulated by mandatory airworthiness standards for designers, which are an integral part of the Aviation Rules. In these standards, the initial requirements for the calculation and experimental works to ensure strength are set, load conditions are established, and instructions are given for determining the magnitude of the loads. In the practice of helicopter construction, the experience accumulated in aircraft construction is used in the formation of structural and power schemes of frame units. The tail beam of helicopters is made according to beam, truss or mixed schemes. Optimization methods of compressed and stretched panels of frame units have a common criterion for aviation - the minimum weight of the structure while meeting the requirements of strength, rigidity, survivability, resource, manufacturability, operational efficiency, etc. The task of selecting a rational structural and force scheme of the tail beam is solved by indirect methods involving weight statistical data, parametric dependencies and information about the force schemes of previous structures. In most cases, the type of tail beam design is selected based on the requirements for the helicopter, operating conditions and production capabilities. The task is to find the best option within a given structural type. The helicopter tail beam is part of the structure of the helicopter, has the shape of a truncated cone and consists of a set of frames, stringers and skin. For ease of manufacturing, the tail beam has a longitudinal technological connector, which allows separate assembly of each half of the tail beam. The tail beam is connected to the central part of the fuselage by bolts that fasten the end power frames with the help of fittings at the ends of the stringers. The end part of the tail beam is connected to the keel, similar to the connection of the tail beam to the central part of the fuselage. The following are installed on the tail beam: stabilizers, rudder control rods, rudder drive system, intermediate and tail gear, navigation lights, assemblies and components of hydraulics and tail shaft. Modern transport helicopters are designed and manufactured with a specified resource and service life in mind, which range from 15,000 to 30,000 hours with a service life of 25-30 years. Increasing the fatigue life of the zones of structural irregularities of the tail beams of transport category helicopters is an urgent task, which is of great practical importance for ensuring the safety of flights during the operation of helicopters during the established resource, which in turn is an important indicator of the competitiveness of helicopters.