Modeling the Mutual Distortions of Interacting Helicopter and Aircraft Wakes

Flight procedures that will decrease the following distance between successive aircraft have been considered as a mea ns of alleviating pressures on airport capacity while still conforming to conventional air trafic management rules. A major limitationto the implementation of such procedures is perceiv ed to be an associated increase in the possible severity ofencounter swith the wakesof nearby aircraft. Modeling efforts have focused on quantifying such interactions in terms of structuralloading or degradationinhandling andhave established that helicopters respond in a fundamentally different way than xed-wing aircraft to encounters with wake vortices. This paper suggests that, particularly at the low forward speeds typical of terminal phase operations, the mutually induced distortion of the helicopter’s own wa ke and the wake of the interacting aircraft strongly in uences the aerodynamics of the helicopter rotor. Results from numerical simulations suggest that neglecting this aspect of the interaction as has commonly been done in the past, can indeed be valid a thigh helicopter forward speeds, but can lead to signi cant misrepresentation of the severity of wa ke encounters under terminal ight conditions.