Several years back, I was in my apartment near the local airpatch. I lived about 250 yards to one side of the approach and maybe 2/3 of a mile from the threshold. All manner of neato aircraft would fly past my balcony at all hrs of the day and night, and I *loved* it. It was like a free airshow all the time. Citations, Challengers, Blackhawks, all manner of bug-smashers...
One day I'm sitting there in the morning, feet up, reading, and I hear this strange sound. It sounds like a jet, maybe a Beechjet or something little. No, no, thats bigger than a Beechjet. What the...?
But then, no, wait, there's this rhythmic sound and... the jet sound gives way to a high-beat rotor system.
I can identify most helicopters from the last 40 years or so by sound. Seriously, I can usually tell within a few seconds the difference, say, between a Bell 412 and a 414, an EC135 vs a Hughes 500, etc. I can literally hear a Chinook 10 miles away, in the background noise, and say "there's a Chinook nearby.."
But this sound. No, this sound isn't anything I've ever heard before. Seriously, like never ever.
I leaped to the doorwall as an Erickson S64 burst over the trees over my head on its way to land at the airport. "wow!"
I took the kids out for lunch and we brought our chow over to the airport so we could see the Aircrane getting gassed up and leave. My daughter was bored.