The shrouded tail (marketed as "Fenestron") of an Airbus Helicopters H135 (formerly Eurocopter EC135)
<a href="//commons.wikimedia.org/wiki/User:Ariadacapo" title="User:Ariadacapo">Olivier Cleynen</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>