Eleni Sotiropoulos
(Advisor: Prof. Mavris)
will defend a doctoral thesis entitled,
Methodology for the Fidelity Assessment and Use of Helicopter Flight Simulators in Vortex Ring State (VRS) Accident Prevention Training 
On
Wednesday, June 25th at 8 a.m.
Collaborative Design Environment (CoDE)
Weber Space and Technology Building (SST II)
and
Microsoft Teams

Abstract
From 2008 to 2021, 48 helicopter accidents in the United States likely involved Vortex Ring State (VRS) encounters. The helicopter community has set ambitious rotorcraft safety improvement objectives for the current decade, which will therefore require mitigating VRS-induced accidents. However, due to the risks involved, training for fully developed VRS during actual flights is discouraged. Thus, simulators could offer a safer alternative for pilot training, provided they accurately replicate helicopter flight dynamics during this phenomenon.
To enable effective VRS accident-prevention training in flight simulators, their ability to represent VRS onset and recovery must be assessed. However, current qualification standards for VRS simulation remain subjective, raising uncertainties about the simulator's suitability for pilot training and the potential risks associated with negative transfers of skills from the simulator to the helicopter. This underlines the need for an objective fidelity assessment framework specific to VRS.  To that end, evaluation criteria are defined based on the results of a dedicated flight test campaign performed on a Robinson R66, as well as flight test data from the literature.  Methods are then developed to evaluate three simulation models against these criteria: the H125 reduced motion platform VR simulator from Loft Dynamics, and two H125 FLIGHTLAB simulation models implemented for this research, one with the Viscous Vortex Particle Method (VVPM) inflow, and the other with a dynamic inflow model.
Once equipped with tools to determine the accuracy of a given simulator, this work designs VRS-inducing scenarios based on accidents and adapted to the simulator's fidelity and capabilities.  A group of pilots then tests this set of scenarios. To demonstrate its use in VRS accident prevention Scenario-Based Training, we evaluate pilots' VRS awareness, avoidance, detection, and recovery during the simulations. In addition, to enhance the simulator flight training experience of both pilots and instructors, a framework is developed to evaluate pilots' performance in VRS recoveries.
The outcomes of this research provide methods for evaluating simulator fidelity in VRS and improving VRS accident-prevention pilot training. The findings aim to advance simulation technologies and training strategies for enhanced rotorcraft safety.

Committee
•    Prof. Dimitri Mavris – School of Aerospace Engineering (advisor)
•    Prof. Daniel P. Schrage – School of Aerospace Engineering
•    Prof. Marilyn Smith – School of Aerospace Engineering
•    Dr. Richard Brown – Sophrodyne Aerospace
•    Dr. Alexia Payan – School of Aerospace Engineering
•    Mr. Charles C. Johnson – Federal Aviation Administration (FAA)