When we are talking about something fly in the air ,we must talk about four forces affect it's motion . These forces are called :(Aerodynamic Forces)
These are lift, drag, thrust and weight or (gravity) . The directions of these forces are shown in the figure below .
In simple terms, drag is the resistance of air (the backward force), thrust is the power of the airplane's engine (the forward force), lift is the upward force and gravity is the downward force. So for airplanes to fly, the thrust must be greater than the drag and the lift must be greater than the gravity (so as you can see, drag opposes thrust and lift opposes gravity).
We will talk about every force :
- The thrust is generated by the airplane's engine (propeller or jet) . After that we may talk about the airplane's engine types and how they work .
- gravity is a natural force acting upon the airplane ( actually it is the weight of the plane and every thing it contain ) and this force exerts vertically downwards .
- We know are going to talk about the ( Lift force ) :
It's a fact that the gases are compressible fluids this means that it's density can be changed because of the fact that says ( any amount of gas can full any volume )
but we still have some questions like ( how wings generate lift ? )
In fact not wings only who generate the lift but all the body of the plane is designed to generate lift but, the wing generates the most lift force and if you understood how do wings generate lift you will understand how the body generates lift .
A cross section of a typical airplane wing will show the top surface to be more curved than the bottom surface. This shaped profile is called an 'airfoil'
During flight air naturally flows over and beneath the wing. Any given 'parcel' of air gets split in two as it hits the leading edge of the wing, and both halves of that parcel actually meet up again at the same moment as they come off the trailing edge of the wing. So because the air moving over the top of the wing has more distance to cover (because of the curvature it is forced to follow) in the same amount of time as the air passing below the wing, it has to move faster.
Faster moving air is less dense than slower moving air, so this speed difference results in a lower air pressure on top of the wing, and a higher air pressure
this difference in pressure generates the lift force this is called below the wing. The result of this pressure gradient is that the wing, and hence the plane, is pushed upwards by the higher pressure.Bernoulli's principle expains the relation between acceleration and pressure .
The physics explanation, NEWTONIAN or ATTACK ANGLE: wings are forced upwards because they are tilted and they deflect air. A wing's trailing edge must be sharp, and it must be aimed diagonally downward if it's to create lift. Both the upper and lower surfaces of the wing act to deflect the air. The upper surface deflects air downwards because the airflow "sticks" to the wing surface and follows the tilted wing (this phenomena is called "Coanda effect" or "Flow Attachment.") After the wing has passed by, air remains flowing downwards. Airplanes fly because of Newton's 3rd law (action/reaction forces,) the law of Conservation of Momentum, and the Coanda effect.
Note well: Newton and Bernoulli do not contradict each other. Explanations which are based on Newton's and on Bernoulli's principles are completely compatible. Air-deflection and Newton's Laws explain 100% of the lifting force. Air velocity and Bernoulli's equation also explains 100% of the lift. For the most part they're just two different ways of simplifying a single complicated subject.
-Drag : it is the net aerodynamic force parallet to the relative wind and is generally a sum of two components :induced drag and parasite drag . ( the drag force is related to the angle of attack ) . I think that it's enough for you to know that the drag is the resistance force that tries to prevent the plane from moving in the fluid (air)
.
(these information are very complicated and there are many argues about this but i tried to simplify it as possible but if you want to study it all you can search in these fields
1- perfect gas theorem ,2- the layers of the atmosphere ,3- compressible fluids ,4-Bernoulli's principle 5-Newton's Laws 6-Aerodynamics .)
The next time we will talk about how the movements of the plane happens (it's very easy).
These are lift, drag, thrust and weight or (gravity) . The directions of these forces are shown in the figure below .
In simple terms, drag is the resistance of air (the backward force), thrust is the power of the airplane's engine (the forward force), lift is the upward force and gravity is the downward force. So for airplanes to fly, the thrust must be greater than the drag and the lift must be greater than the gravity (so as you can see, drag opposes thrust and lift opposes gravity).We will talk about every force :
- The thrust is generated by the airplane's engine (propeller or jet) . After that we may talk about the airplane's engine types and how they work .
- gravity is a natural force acting upon the airplane ( actually it is the weight of the plane and every thing it contain ) and this force exerts vertically downwards .
- We know are going to talk about the ( Lift force ) :
It's a fact that the gases are compressible fluids this means that it's density can be changed because of the fact that says ( any amount of gas can full any volume )
but we still have some questions like ( how wings generate lift ? )
In fact not wings only who generate the lift but all the body of the plane is designed to generate lift but, the wing generates the most lift force and if you understood how do wings generate lift you will understand how the body generates lift .
A cross section of a typical airplane wing will show the top surface to be more curved than the bottom surface. This shaped profile is called an 'airfoil'
During flight air naturally flows over and beneath the wing. Any given 'parcel' of air gets split in two as it hits the leading edge of the wing, and both halves of that parcel actually meet up again at the same moment as they come off the trailing edge of the wing. So because the air moving over the top of the wing has more distance to cover (because of the curvature it is forced to follow) in the same amount of time as the air passing below the wing, it has to move faster.
Faster moving air is less dense than slower moving air, so this speed difference results in a lower air pressure on top of the wing, and a higher air pressure
this difference in pressure generates the lift force this is called below the wing. The result of this pressure gradient is that the wing, and hence the plane, is pushed upwards by the higher pressure.Bernoulli's principle expains the relation between acceleration and pressure .
The physics explanation, NEWTONIAN or ATTACK ANGLE: wings are forced upwards because they are tilted and they deflect air. A wing's trailing edge must be sharp, and it must be aimed diagonally downward if it's to create lift. Both the upper and lower surfaces of the wing act to deflect the air. The upper surface deflects air downwards because the airflow "sticks" to the wing surface and follows the tilted wing (this phenomena is called "Coanda effect" or "Flow Attachment.") After the wing has passed by, air remains flowing downwards. Airplanes fly because of Newton's 3rd law (action/reaction forces,) the law of Conservation of Momentum, and the Coanda effect.
Note well: Newton and Bernoulli do not contradict each other. Explanations which are based on Newton's and on Bernoulli's principles are completely compatible. Air-deflection and Newton's Laws explain 100% of the lifting force. Air velocity and Bernoulli's equation also explains 100% of the lift. For the most part they're just two different ways of simplifying a single complicated subject.
-Drag : it is the net aerodynamic force parallet to the relative wind and is generally a sum of two components :induced drag and parasite drag . ( the drag force is related to the angle of attack ) . I think that it's enough for you to know that the drag is the resistance force that tries to prevent the plane from moving in the fluid (air)
.
(these information are very complicated and there are many argues about this but i tried to simplify it as possible but if you want to study it all you can search in these fields
1- perfect gas theorem ,2- the layers of the atmosphere ,3- compressible fluids ,4-Bernoulli's principle 5-Newton's Laws 6-Aerodynamics .)
The next time we will talk about how the movements of the plane happens (it's very easy).
Thank you for sharing this information.
ReplyDeleteIt will really helpful to solve my confusion
Process $ Chemical Engineering