Lichten Award Paper: Correlation of Rotor Loads during Ground Operations in a Turbulent Wind Environment

Rotorcrafts frequently operate in environments with severe atmospheric turbulence, for instance transferring people offshore to and from oil rigs as well as operating from and around ships. The presence of high turbulence can deteriorate performance, stability, and controllability of the rotorcraft. Additionally, such challenging conditions also generate loads that both airframe and rotor components must withstand. Following this, it is crucial to consider the impact of these operational atmospheric conditions during rotorcrafts design and development. In this context, numerical models are a fundamental tool to provide an easier and quicker way to explore the operative envelopes of the helicopter compared to performing experimental activities. This paper presents a rotor loads correlation activity between an experimental test designed and carried out by Leonardo Helicopters in which an AW189 helicopter was placed in the wake of a C-27J Spartan aircraft and a multibody structural model built using MSC Adams®. Furthermore, an atmospheric turbulence model is proposed and compared with the wind experimental records with the purpose of defining an analytical tool for the estimation of the wind time histories. The main purpose of the work is to detail the extensive correlation activity and highlight the modeling key ingredients to consider for an accurate load prediction in a turbulent wind environment. The correlation focuses on the effect of the wind during ground operations, considering the rotor at rest or running up/shutting down.