Dynamic analysis and simulation of a generic rotorcraft-load system and a case study on a specific complex PCDS (Personnel Carrying Device System)

The primary objective of this thesis is to present an algorithm for numerical implementation that enables to simulate the dynamics of rotorcraft-load combinations. Executed in a numerical simulation environment such as MATLAB, the algorithm reproduces a predetermined kinematic motion of a helicopter and derives the consequent dynamics of all suspended loads, connected to it in any configuration, analyzing the state variables and the forces acting on the bodies. This master's thesis work was carried out in collaboration with Umberto Ciarlo, a university colleague, as a part of a broader project in which TPS Group S.p.A. is involved - a leading company in technical and engineering services for the aeronautical industry, and a leader in several other industrial sectors. The basic intention of this work is to serve as a practical tool to perform simulations where multiple external loads are suspended from a helicopter during both Human External Cargo (HEC) and Non-Human External Cargo (NHEC) operations. In particular, the algorithm is applied to the innovative and unconventional configuration proposed by TPS Group S.p.A. for the transport of external loads suspended from an Aérospatiale AS-350 Écureuil helicopter. The proposed algorithm enables the computation of the state variables of all bodies, the determination of the forces acting on each helicopter hook and even the simulation of the load release, as it may occur in emergency situation due to inadvertent hook opening or intentional jettison. The ultimate goal is to understand how the dynamics of external loads influence the helicopter's behaviour through the resultant forces transmitted to the hooks. Following an initial overview of the previously developed designs for external suspension systems, the mathematical model is presented, basing on the Newton-Euler equations of motion and the analytical model proposed by L. S. Cicolani and G. Kanning. Several examples are then analyzed to validate the implemented model, as well as many interesting conclusions and results are discussed. Additionally, a summary on the applicable European regulations on air operations is provided. This thesis is a complementary work to Umberto Ciarlo's thesis, and together they establish, as a long-term objective, the foundation for a simulator in which the coupled dynamics of both the helicopter and the external cargo are modeled, enabling high-fidelity analysis of how external loads influence the helicopter's handling qualities.