When creating rocket and space technology parts from composites, the tasks of design, material selection and manufacturing technology are solved simultaneously. The paper presents an experimental study of polymer composite materials (PCMs) based on carbon, glass, and aramid fillers, which can be used in the rocketry industry as part of fuel tank structures. Much attention is paid to the use of new and promising materials that combine unique physical and mechanical properties, their features, along with the improvement of manufacturing technology, which is the most urgent task of today. The technological parameters of the materials under study are described, and their distinctive features are identified. The physical and mechanical properties (density, elastic modulus, shear modulus, Poisson's ratio, tensile strength) are determined together with the compilation of the corresponding strength criteria, which allows for optimising the choice of reinforcing components depending on the operating conditions. The strength calculation of composite fuel tank shells made of the considered materials was carried out with the subsequent determination of the initial geometrical parameters of the structure. The formed research algorithm includes the mathematical determination of the geometric parameters of the structure when analysing the possibility of using different types of reinforcing materials for the power shell made of polymer composite materials. The results and recommendations for improving materials and technologies to increase the efficiency of fuel tank structures in rocket and space technology are presented. Based on the results, the conclusion is that carbon fibre-reinforced plastic is the most appropriate choice for this class of structures, as it provides an optimal combination of low weight, high strength, and resistance to aggressive (cryogenic) environments.