Fuselage-Rotor Interference Including Side-Slip Angle

Abstract

A semi-empirical and physics-based analytical formulation of the induced velocities generated by the fuselage shell of the Bo105 wind tunnel model in the volume around the rotor is derived from velocity data computed by a panel code. The re-duced-order analytical model is several orders of magnitude faster than the panel code and thus is predestinated for use in comprehensive rotor codes. Angle of attacks investigated range from vertical descent, shallow descent, level flight and climb to vertical ascent and side-slip angles range from forward to quartering flight. The analytical induced velocity model can directly be used to account for the inflow at the blade elements and also allows for analytical or numerical integration of rotor wake convection to compute the associated displacements of rotor blade tip vortices travelling downstream within this velocity field. The focus of this paper is the analytical evaluation of fuselage-rotor interference in side-slip angles on rotor trim controls, using blade element momentum theory. The results are compared to the influence of thrust-induced inflow gradients on rotor trim.