Here is a really cool video that explains how a radial engine works. It is a highly detailed wood replica. All I can say is wow.
linky (https://m.facebook.com/story.php?story_fbid=1064015557001481&id=139188202817559)
Very cool. These engine were the height of piston super-power.
When I was first breaking into aviation there were still a lot of DC-3/4/6s flying, I was flying a Twin Beach, the USCG still had the Albatross: the sonds around the airport were different, very distinctive.
Legend has it that the Connies, the DC-7s, and ultimately the Albatrosses couldn't fly any more because the 115/145 avgas was not made any longer, and take-offs at less than rated power were either not authorized (USCG) or impracticable given the reduction in gross.
You could always tell a round-engine crew by the oil spots on their shirts. Sometimes just cranking the engines through would not clear the bottom cylinders and you had to pull the plugs.
Great memories.
The one thing to remember about radials. If they're not leaking oil, the oil tank is empty.