Bell 412 modeling and model fidelity assessment for level-d training simulators

This paper presents the validation of a Level-D rotorcraft simulation framework by comparing different quantitative model fidelity metrics. The simulation framework uses a non-linear blade element rotor model to simulate the flight dynamics of rotorcrafts with accurate stability and control characteristics identified from system identification techniques. For this study, frequency-domain system identification is used to generate linear state-space 6-DoF quasi-steady models and an automated process is used to adjust the non-linear simulation framework. Regulatory authorities assess performance models for Level-D simulators by comparing time-domain simulation responses with measured aircraft responses for the same set of control inputs. Over the years, new quantitative fidelity metrics were proposed, like the Maximum Unnoticeable Added Dynamics and the Allowable Error Envelopes. This paper will focus on the blade element rotor model hover modeling process to demonstrate its application using a Bell 412 flight test data package. It will also show how this modeling approach can be used to match both Level-D requirements and the alternative fidelity metrics stated above.