At exactly 9-AM--hearing it before seeing it--and it was only about 100-feet above Winter Harbor--having just "saluted" the old airport. He then overflew the Libby Museum. What was remarkable is he would have crossed the old runway at 90 degrees, and cleared our 100-foot pines with little space to spare.
I believe it is the "usual"
Saturday Sukhoi acrobatic monoplane that does loops and spirals above Rattlesnake Island nearly every weekend. Yes, you do have to look up--and it helps to hear it first!
It could be a
Yak--they're similar
planes, even at 100 feet altitude. Both are equipped with the radial (round) engine that won WWII.
ETA:
