Lifting-line theory

Lifting-line theory is like playing with a toy airplane! Imagine you have a toy airplane, and you are holding it up in the air with your hand. If you move your hand, the toy airplane will move too, right?

Well, in real life, airplanes work the same way. When an airplane moves, it creates air flow over its wings. This air flow creates a force called lift, which helps keep the airplane in the air.

Lifting-line theory is a way of thinking about how this lift is created. Imagine you take a line and wrap it around the airplane's wings, like a big hug. This line is called the lifting-line.

Now, imagine the airplane is flying through the air. The air will flow over the wings and create lift. But what if we apply the same force to the lifting-line that we would apply to the airplane? The lifting-line will start to bend and curve, just like the airplane's wings!

Using some math and physics, we can figure out how much lift will be created by the curving lifting-line. This helps us understand how much lift an airplane will create, and how we can make it more efficient.

So, lifting-line theory is basically a way of thinking about how airplanes create lift, using a simple imaginary line wrapped around their wings. It helps us understand how airplanes work and how we can make them better!