What is the purpose of flaps on an airplane?

Aircraft flaps are a high-lift device designed to increase aircraft lift once a certain speed is reached. Flaps help the wings adapt to whatever phase of flight they may be in. The usage of flaps on wings provide these three major advantages:

1. More lift is produced, allowing for lower takeoff and landing speeds
2. More drag is produced, creating a deeper descent angle without increased speed
3. Length of takeoff and landing roll is reduced

There are four major flap designs that are applied to planes. As with anything, each has advantages and disadvantages, but all are important for proper airplane function.

Plain Flaps

• Hinge to the back of the aircraft wing
• Pivot down when extended
• Drag created allows for a steeper descent when landing without increased airspeed

Split Flaps

• Deflect from a lower part of the wing’s surface
• Produce more lift, but have a lot of drag
• Uncommon on new planes, mostly found on warbirds

Slotted Flaps

• Most commonly used, can be applied on small and large aircrafts
• Increase wing camber
• When extended, a slot between the wing and flap opens, allowing high-pressure air to flow through to the upper surface of the wing
• Lots of lift, little drag

Fowler Flaps

• Increase aircraft wing area
• Have large slots, called slotted-Fowler flaps, that add energy to the airflow
• When Fowler flaps extend, lift increases a large amount while drag only increases a little
• As flaps fully extend, they move downward and create a little more lift and a LOT more drag

Keep in mind the importance of using the recommended flap setting. You should never reduce a flap setting while in a turn because it could result in a stall or spin out.