Numerical Investigation of Helicopter Mast-Bumping Susceptibility in Low-G Conditions

Abstract

This paper presents a numerical investigation of helicopter mast-bumping susceptibility in low-G conditions using a comprehensive aeromechanics code. The primary objective of this study is to provide qualitative insights for educational purposes, focusing on the fundamental flight-mechanical effects of helicopters in low-G environments. A key aspect of the research is the comparison between helicopters with zero flapping-hinge offset and hingeless rotors with high flapping stiffness. The study examines the flight-mechanical effects of helicopters during the transition into a low-G dive maneuver, highlighting the influence of the rotor system and different recovery strategies. Furthermore, the influence of flight conditions, such as velocity, and configurational aspects, including stabilizer design, is analyzed. Here, the specific focus is dedicated to the occurring flapping angles, as they directly determine the onset of mast bumping. The findings emphasize the advantages of hingeless rotor systems in low-G conditions, particularly in terms of controllability, and confirm previous results and safety recommendations to mitigate the risk of mast bumping.