Community Noise Assessment of Hybrid-Electric Aircraft Using Windmilling Drag on Approach

Abstract

The modeling and assessment of the community noise impacts of a representative hybrid-electric aircraft implementing windmilling motors as drag generators on approach is presented. An increasing desire to reduce emissions caused by aviation has motivated the development of hybrid-electric aircraft that have some degree of their traditional gas-turbine propulsion replaced with electric propulsion. Turboelectric propulsion offers flexibility in the engine architecture that allows hybrid-electric aircraft to be capable of certain advanced operational noise abatement flight procedures. Steep and delayed-configuration approaches are example flight procedures that enable significant noise reductions on approach but require the aircraft to have enough drag for the approach to be stable. Windmilling is an alternative mechanism to create drag during descent and is possible in architectures where the fan is powered by an electric motor. Results examining the potential benefits of representative turboelectric aircraft implementing this controlled drag concept on both delayed deceleration and steeper approaches are presented. The results indicate that windmilling fans are quieter than standard drag-producing devices and can be used to yield significant community noise reductions compared to aircraft performing standard 3 deg continuous descent approaches.