Methodology and program complex of research of longitudinal static sustainability of screen plane at the design stage

This paper deals with the research methods of wing-in-ground effect vehicle (WIG vehicle) longitudinal static stability. The methods are focused on the use of the algorithm of preliminary WIG aerodynamics and control system design. The algorithm is based on the iteration process of stability criteria calculations, the subsequent factor analysis of these criteria with respect to their value-determining parameters and variations of WIG vehicle configuration parameters. The methods include preliminary determination of WIG vehicle aerodynamic characteristics. The best results can be obtained when different methods of determining these aerodynamic characteristics (experimental and by means of computational aerodynamics) are combined. In this paper the calculation of aerodynamic characteristics is performed by applying ANSYS software packet. To assess the reliability of the aerodynamic characteristics obtained with the ANSYS program, experimental studies in a wind tunnel and a vertical hydrodynamic pipe were carried out. Certain aerodynamic characteristics are determined by means of originally made computer programs using the method of discrete vortices. A special database is formed of the obtained aerodynamic characteristics. The database essentially is a mathematical model of a WIG vehicle which supplies the characteristics (aerodynamic coefficients and their derivatives) with an estimated degree of reliability within a given range of determining parameters. On the basis of the widely used criterial approach to static stability assessment of various WIG vehicle modifications, a mathematical algorithm for parameter calculation and a computer program were developed. They permit the calculation-based analysis of the factors determining stability or non-stability of a WIG vehicle. The mathematical model of WIG vehicle stability analysis is implemented in the form of a software packet based on MatLab. The results worked out by the program are in the form of data suitable for operational analysis. Using these data, one can assess the WIG vehicle static stability and determine the stability range for the given structural and configurational factors. The results of the analysis make a foundation for subsequent modifications of WIG vehicle's aerodynamic configuration or for working out requirements for automatic control and stabilizing systems' upgrade. The methods demonstrating the analysis of original load-carrying systems design are also presented. For the example analysis, an original WIG- tandem load- carrying system was chosen. The methods are applicable for the analysis of various aircraft modes' stability, for all vehicles built on aerodynamic principles of flight maintenance.