Relative wind is an important concept in aviation. Whether it’s a small Cessna 172 or a jumbo-sized Airbus A320, all airplanes are affected by the wind. It can affect their speed, fuel efficiency and overall performance. Pilots must understand the concept of relative wind to maintain flight stability and maximize efficiency.
Overview of Relative Wind
Relative wind can be described as air that moves opposite to an airplane’s path of flight. During flight, the air will push against airplanes in the opposite direction to which they are flying. Known as relative wind, it’s essentially the direction of the wind “relative” to the direction in which an airplane is flying.
It’s important to note that relative wind isn’t the actual or true direction of the wind. Even if the wind is moving from the West to the East, the relative wind will still be opposite to the airplane’s path of flight, regardless of the airplane’s cardinal direction. When an airplane moves forward, the air or wind will push against it in the opposite direction.
Relative Wind and Lift
The amount of lift airplanes produce is affected by relative wind. Lift, of course, is one of the four forces of flight. As air flows over and under an airplane’s wings, lift is created. The difference in pressure between the air moving over and under the wings creates lift.
The angle of attack is the angle at which an airplane’s wings meet the relative wind. As the angle of attack increases, lift will increase — but only to a certain point. After reaching this limit, lift will decrease.
Relative Wind and Drag
In addition to lift, drag is affected by relative wind. Drag is also one of the four forces of flight. It’s the force that slows down airplanes forward motion. It’s caused by the interaction between an airplane’s solid body and the wind.
When an airplane moves through the air, it will face resistance. The relative wind, which determines the airplane’s angle of attack, will influence how much resistance or drag the airplane experiences.
A low angle of attack will result in less lift and less drag. A medium or moderate angle of attack will generate sufficient lift. A high angle of attack, on the other hand, will create more lift at the cost of significantly more drag. And if the angle of attack is too high, the airplane will stall.
