5 Key Aerodynamic Facts Every Pilot Should Know About Flaps

By Wiley Stickney

Published on

Hey there, pilots! Let’s talk about flaps and why they’re so important. These facts are crucial knowledge for any aviator:

1. Flap Extension Changes the Wing’s Curvature

When you extend those flaps, it modifies the curvature, or camber, of your wing. This adjustment reduces your aircraft’s stall speed while increasing drag. With a greater camber, your wing can generate more lift at a given angle-of-attack. Pretty neat, right?

2. Flap Extension Lowers Stall Speed

By deploying those flaps, your wing generates more lift, so you don’t need as much angle-of-attack to keep those four forces of flight in balance. As a result, when you’ve got those flaps extended, your stall speed decreases. Handy for landing, isn’t it?

3. Flap Extension Increases Drag

As the saying goes, “nothing in life is free,” and the same principle applies to lift. When you increase lift by extending flaps, you also increase induced drag. However, this added drag can be a good thing, especially when it comes to landing, which we’ll discuss shortly.

4. Takeoff Flap Settings Are Usually 5 to 15 Degrees

During takeoff, aircraft typically use flap settings ranging between 5 and 15 degrees (most jets also use leading-edge slats). This is quite different from landing procedures, where aircraft usually deploy 25 to 40 degrees of flaps. Why the difference? By extending the flaps moderately, aircraft benefit from increased lift due to camber without the high drag associated with fully extended flaps.

5. Full Flaps Are Typically Used for Landing

When coming in for a landing, pilots often deploy full flaps to maximize both lift and drag generated by the wing. This has two main advantages: First, it reduces the stall speed, allowing for a slower approach. Second, it enhances drag, enabling a steeper descent angle towards the runway.

Wiley is a former commercial pilot and flight instructor, who has flown over 50 different types of aircraft, from small propellers to large jets. He writes about the technical aspects of flying, such as aircraft design, aerodynamics, navigation, weather, and safety.