On the noise of electric aircrafts: from drones to electric airplanes

In recent years, the aeronautical industry has seen a rise in aircraft projects utilizing electric propulsion, which can be grouped into three categories. The first includes conventional aircraft adapted with electric motors and propellers to reduce CO 2 emissions. The second involves electric aircraft designed for urban mobility-commonly known as eVTOLs (Electric Vertical Take-off and Landing) or air taxis-intended to transport people within metropolitan areas. The third focuses on logistics, using small electric aircraft or drones to deliver goods from distribution centers to customers, aiming to reduce urban traffic. A common feature of drones and eVTOLs is their operation within urban areas, where noise becomes a major concern. This lecture addresses key aspects of electric aircraft noise, both internal and external, and the potential impact of these new vehicles on urban soundscapes and passenger comfort. It first reviews the primary sources of noise and vibration, along with mitigation strategies applicable to these aircrafts. The presentation also highlights ongoing research aimed at reducing noise and vibration, and the numerical and experimental tools used in these studies. Finally, it explores the challenges of ensuring that new aircraft meet safety and comfort standards while minimizing their impact on users and public health.