There are certain sounds that pilots and aviation fans know well, such as the wail of a jet engine starting, a vintage radial engine cruising overhead, or the chirp of aircraft tires touching down on an asphalt runway.
Then there is the telltale staccato rhythm emitted by the two-blade rotor assembly of the Bell UH-1 Iroquois helicopter, better-known as the Huey. The thumping sound of this long-lived machine has echoed around military bases, airports, and low-altitude flight paths for nearly 70 years.