ON DETERMINATION OF INTERNAL DRAG WHEN TESTING MODELS OF INTEGRATED AIRCRAFT WITH DUCTS

Abstract

The problem of determining the internal drag in ramjet integrated layouts is considered. It is shown that the standard technique for internal drag adjustment in tests of aircraft models with a duct developed for axisymmetric layouts can lead to differences in adjustment values when applied to the integral layout of the lifting body with an under-fuselage ramjet. It is proposed to include the aerodynamic drag of the external compression inlet braking body in the aerodynamic characteristics of the airframe, as well as to determine the internal drag only within the limits of the duct itself (i.e., from the mouth to the nozzle exit) and the need to measure the flow parameters in both the nozzle exit section and at the duct mouth. Calculation estimates of the internal drag of the integral layouts using the Navier-Stokes equations are given.