Okay kiddo, so you know how airplanes have to fly in circles when they're trying to fight each other, right? Well, sometimes when two airplanes are chasing each other in circles, they end up in a very special kind of circle called a Lufbery circle.
In a Lufbery circle, the two airplanes are flying very close to each other but always going in opposite directions. This makes it really hard for one plane to shoot the other because they're always moving away from each other. It's sort of like if you were trying to tag someone and they were running the other way!
The term "Lufbery circle" comes from a famous World War I pilot named Raoul Lufbery, who was really good at flying this way. Pilots who use this tactic today still use his name to remember how great he was at it.
So, to sum it up, a Lufbery circle is when two planes are chasing each other in opposite directions, making it hard to shoot each other. And it's named after a really cool pilot from a long time ago. Pretty neat, huh?