From take off to landing - ''How do airplanes fly?'' An amateur edition

Alright, time to brush your science basics before we climb aboard. As this is an amateur edition, I will try to limit myself to Newton's laws to help you have a basic understanding of how airplanes fly.

 Newton's laws explained intelligibly:

The first law:  "Static things don't move unless something pushes them and moving things don't stop unless something stops them." So, you might be thinking, when I release the accelerator in my car and don't push the brakes, the car should keep on moving, right? wrong. Here on earth, the car eventually stops because of a resistive force due to friction between two surfaces. When you rub your hands, you feel a force acting against the direction of motion called frictional force. So when you release the accelerator, the frictional force between the tire and road the road that acts against the direction of motion, makes sure that the car is brought to rest. In airplanes, even though the presence of air is the reason why airplanes fly, there is a resistance force generated between the surface of the airplane and air. Aerodynamicsts call it 'drag' which is nothing but force generated by friction.

Also, If you kick a ball in space, it will keep on going(forever) until it approaches an obstacle like an asteroid or a gravitational influence of a planet or a star. This happens because of no presence of an atmosphere, hence no air, hence no friction.

The second law: "The amount of force required to move a body increases with the mass of the body that has to be moved" Which means if you use the same amount of force to move a chair and a sofa, the chair will have more acceleration than the sofa.

The third law: "Every action has an equal and opposite reaction." A swimmer pushes the water backward and water pushes the swimmer in forwards direction. also, when a mountain climber pulls down the rope, the rope pulls up on the mountain climber.

Now that we are pretty confident with Newton's laws, let's step into Aeronautics.

There are four forces that act on an airplane:

Source: Google images

The weight of the airplane acts towards the center of the earth due to gravitational attraction. Drag, among many other reasons, is mainly generated due to frictional forces between the surface of the airplane and the air flowing over it. which implies, more surface of the aircraft is exposed to air, more amount of drag the airplane experiences. (There are many types of drags that slow down the aircraft such as, lift-induced drag, wave drag, etc., which we will not be studying here). Apparently, from my experience, most people I meet(not my classmates. of course.), when I ask them, "Do you know what makes an airplane fly?'', the most common answer I receive is, THE ENGINES. Most of you are partially right but not completely. Engines do not lift the plane upwards, They just provide thrust force which helps the airplane to move in a forward direction. 

Lift force, the protagonist of this article is the main reason why an airplane takes off and stays up there. So, how is this lift force generated? The main reason lies in the shape of the wing. When you take a slice of the wing, also called the cross-section of the wing, it looks like this,

This shape is called an airfoil and the lines shown in the above image are called streamlines which basically denote the direction of the airflow or the path followed by the air particles. When the engines generate thrust and move the airplane in a forward direction, air flows over the wing like this.

What basically happens here is, the airfoil is shaped in such a way that, it pushes the air downwards. And, referring to Newton's third law, the air pushes the airfoil upwards generating lift force thus, helping the aircraft to take off and stay there. This implies if there were no atmosphere present on our planet, the airplanes that are designed the way we use them today would never take flight.

Also, you may have observed many race cars having a rear wing called a spoiler. These wings are designed exactly opposite to the ones in aircraft which  looks like this,

These spoilers push the air upwards which eventually resulting in the air pushing the spoiler downwards generating a force called the 'downforce'.

came this far? thanks for reading. feel free to use the comments section and also if you are interested, please subscribe to my posts by entering your e-mail address in the follow-by-Email available on the 3rd box on the top right.

*P.S. This phenomenon can also be explained using Bernoulli's principle and variation of pressure distribution.*