Big round vintage military engines, nothing like the sound. There are a couple local C-47 types I see periodically going over. And some summers when an aircraft is visiting my home as been on the circle path they take passengers on. Kinda cool when they go overhead every hour or so. Wish I'd had a camera for a B-17 a couple years ago, overcast and I could hear it coming, and it burst out of the low cloud right in front of me. Would have been a cool photo as it came through.