Published online by Cambridge University Press: 04 July 2016
This paper deals with the methods of physical modelling of Flight Control Systems (FCS) by means of Dynamically Similar free-flying Models (DSM) for the investigation of stability and controllability of aircraft at subsonic flight speeds. The subsonic flight regime allows us to avoid Mach number similarity considerations. The large scale of the DSM meets autosimilarity of Reynolds numbers, whilst Froude similarity is assured during the development and manufacturing of the DSM. This paper proves the presence of necessary and sufficient conditions of similarity for the FCS of an aircraft, and that of its DSM. The existence of necessary conditions have been proved both mathematically (by means of the π – Theorem from the theory of dimensions), and with equations involving physical quantities. The generalised scale coefficients for transitioning from the FCS’s aircraft gain factors, to those of the FCS of the DSM have been obtained, and it is shown that the coefficients depend only on the linear scale of the DSM.