Validation of helicopter noise prediction system with flight data

A comprehensive noise prediction system is required to predict helicopter noise and assess potential noise mitigation strategies. It is necessary to validate and understand the limitations of the noise prediction system before it can be used to develop noise abatement procedures. Here, the validation is carried out by direct comparison with the flight test data. This paper gives a brief introduction to the noise prediction system, processing of the flight test data, and development of the different helicopter models with parametric sensitivity. The validation process is carried out by comparing the sound exposure level (SEL) noise contours on the ground plane of the acoustic flight test data with that predicted by the noise prediction system. The examples considered are: level flight; descent flight; level turn maneuver in left and right direction; level, decelerating turn maneuver; and a descending turn maneuver. This range of flight conditions was necessary to analyze the prediction system and understand its capabilities and deficiencies for future work. Overall the predicted noise levels were able to match the trends and levels within a few SELdBA of that measured during the flight test.