[Army Air Corps]

You said it. There is something very evocative about the sound of a Merlin engine. Everything about it is unique. The sound of the starter, the wind-up, the ignition, warm-up, etc. Also, when one makes a low pass, the combination of a faint whistle from the propellor tips and the smooth growl of the engine is ethereal and sublime.

[HKMk23]

...faint whistle from the propellor tips and the smooth growl of the engine is ethereal and sublime.

Indeed, and a sensory indulgence to be breathed in and savoured.