# Practice English Speaking&Listening with: How do Airplanes fly ?

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air planes fly?

airplanes have certainly revolutionized the way we travel.

But, have you ever thought of how it flies ?

How does it navigate ?

We will get answers for these questions

from this video in a simple, yet scientific way.

We will also explore how the flight is controlled in a real-time manner.

First, let's look at some history.

Many crazy flying machine designs were tested

in the nineteenth century because of mankind's quest to fly.

Finally one attempt succeeded.

Yes, you are right.

It was the flight of the Wright brothers.

Their aircraft was a success thanks to an interesting phenomenon of physics.

The airfoil technology.

The wing of the aircraft was able to produce a lift

force in an ingenious way.

The wings had a curved shape.

This shape pushes the gushing air downwards as shown.

Newton's third law of motion comes into picture here.

If the wing pushes the air downwards,

the air should also push the wing in the opposite direction

with an equal magnitude.

This eventually results in the lift force

and the aircraft will be able to fly off the ground.

Even today the airplanes make use of the same airfoil technology to fly,

but with a highly aerodynamically optimised airfoil shape

Thrust force makes an airplane move forward

To produce this thrust,

a turbofan engine is used in modern civil aviation aircraft.

Reaction force of high-velocity exit jet gives the turbofan engine thrust force.

To produce this high velocity jet,

the incoming air is passed through

a compressor, combustion chamber and turbines stages.

The engine also drives the thrust force from the fans reaction

Thus the turbofan engines produce a great amount of thrust

and make the airplane move forward.

As discussed earlier when the airplane moves forward the relatively flowing air

over the wing will produce a lift force on the wings.

Just pause for a moment here and have a closer look at the wing.

You can note that

the wing of a modern aircraft is a collection of different parts.

During take off,

the flaps and slats are extended downwards as shown.

This increases the wing area and curvature of the airfoil.

As the curvature increases air will be deflected more.

Thus a greater lift force can be derived even at low airplane speed.

As the airplane speed increases, the lift force rises.

Finally when the lift is more than the gravitational force,

the plane takes off.

During the normal flight,

the flaps and slats are put it to its original position.

It is interesting to note that,

different forces acting on the airplane balance exactly each other

during the normal flight.

Now, let's get into the core of the flight navigation.

You can navigate the airplane

the way you want with the help of three different wing attachments.

Aileron

Elevator

and Rudder

Pilots use them alone or together depending on the situation.

Assume you want to descend the airplane.

You can just lower the elevator.

This will deflect the flow as shown and will produce a lift.

The lift force will create a moment that will make the nose of the plane go down.

If you want to climb up,

just do the reverse.

Now, let's assume the airplane has to

change it's path.

Just turn the rudder.

Of course, turning the rudder

will produce a lift force and make the airplane turn as shown.

But, such a sudden change in flight direction may cause passenger discomfort.

The professional way is the use of Ailerons.

Just make one Aileron go up and the other down.

This will cause difference in the lift forces and the airplane will roll.

Now observe what happens,

if the airplane still goes up.

It is clear that,

the airplane has changed its path.

Unlike the previous method,

the airplane orientation has not changed here.

All these movement of flaps and

other devices are controlled from the cockpit using a Fly-by-Wire system.

In FBW systems the controller computer governs

exact movement of actuators for a smooth operation.

You can see the different controllers pilots use to navigate the airplane.

Fuel required for the airplane is

stored in the large

tanks of the wing.

During landing, it is required to increase the drag.

For this purpose flaps and slats are activated again.

Because they have drag racing capability too.

A wing attachment called spoiler

is also activated to increase the drag further and reduce the lift.

An interesting mechanism is used for lowering the flaps.

The mechanism will rotate as well as displace the flaps.

We hope you enjoyed the flight journey

by exploring the science behind the airplane operation.

Thank you !

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