Consideration of Atmospheric Properties when Comparing Mathematical Models of Aerodynamic Сoefficients with Flight Test Data

Methodological approaches to the calculation of atmospheric parameters, primarily air density and velocity head, in the task of comparing flight data with the results of mathematical modeling of the aircraft motion are proposed. Models with different degrees of using onboard measurements and standard atmosphere models are considered. The models are compared according to the data of flight experiments performed on a modern aircraft for such flight modes as horizontal platform, turn, climb, descentin, and acceleration. The comparison results are given the form of absolute and relative discrepancies in temperature, static pressure and air density. It is shown that the difference between the properties of the real atmosphere and the standard atmosphere is the main source of mismatches, compared to which the influence of the type of flight modes, altitude, speed is insignificant. In addition, a comparison of the standard atmosphere model with the data of atmospheric meteorological sounding is made, which gave similar results. It is concluded that the calculation of air density and velocity head through the standard atmosphere, widespread in practice, in the general case creates a significant error, which may lead to erroneous conclusions in assessing the correspondence of the aircraft mathematical model and the real object This work was supported by the RFBR, project no. 20-08-00449

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