Unless you’re someone we’d really like to get to know better, it’s likely you’re not flying around in your own personal jet. Which means you probably are flying behind, between, below or in front of at least one propeller. They’re marvelous devices, often subjected to substantial forces as they unceasingly (we hope) spin thousands of times per minute. They also can be a bit mysterious, even the fixed-pitch variety.
At its most basic, an aircraft’s propeller simply is a rotating airfoil used to displace air. Since it is an airfoil, the nasty characteristics we sometimes associate with a wing—including stalls and induced drag—accrue, right along with the good ones, like predictability. And as with a wing, understanding how they do what they do, along with how the more complicated versions work, plus their care and feeding always should be of interest.