CNET:

When I was a kid, one thing I always had trouble wrapping my head around was how fighter pilots with propeller planes would shoot their machine guns through the propeller. I later learned it was all about timing the shots so they wouldn’t interfere with the propeller by syncing up the gun and propeller mechanically. But knowing something is a lot different from seeing it.

This is one of those things that fascinated me as a kid and when I found the solution, I thought it was an utterly brilliant use of technology.