Technique for the experimental determination of the force coefficient of the frontal co-resistance of unstable in flight bodies

Abstract

One of the most important problems in the design of modern aircrafts is the study of the force effects of high-energy flows on the elements of their structures and on the aircraft as a whole. Aeroballistic installations are widely used as a research tool. Determination of the drag force coefficient is the main task of experimental ballistics from which aerodynamic studies begin. The studies are designed to determine the drag coefficient of missiles having different aerodynamic shapes, which can be used in rocket science, artillery, and other areas of technology involved in the study of the movement of bodies in gaseous and liquid media. A feature of the aeroballistic method for determining the coefficient of drag force is that, in order to obtain values of CXO of a given accuracy, experiments can be carried out only with bodies that are stable during the whole time of movement in the studied section of the trajectory. The research is aimed at solving the problem of calculating the drag coefficient of bodies using trajectory data on their coaxial movement. During the ballistic test, the body is sequentially photographed relative to a fixed coordinate system, coordinates of its characteristic points and the time between the moments of photographing are recorded, and the displacements of the characteristic points of the body relative to the moving coordinate system associated with the base body performing a rectilinear motion with a zero angle of attack, are simultaneously measured. In this case, the base body is axially and movably connected to the body under study. It is shown that the applied group motion effect allows, within the framework of the accepted assumptions, to increase the accuracy and simplify the determination of the drag force coefficient of bodies of a complex geometric shape.