Forces Acting on an Airplane During Flight

Written by:  • Edited by: Jason C. Chavis
Updated May 28, 2010
• Related Guides: Aircraft | Airplanes | Teaching Students

It is a very cool experience to sit in the comfortable seats of a jet liner, sip the drinks that are served, stuff yourself with excellent food and simply doze off, only to wake up thousands of miles away later on. But have you ever thought about the forces that were acting while you were asleep?

What Types of Forces Act on an Airplane?

We all love to fly in aeroplanes but we seldom give a thought about the dynamics involved in the flight of an airplane. There are several types of forces which act on an airplane while it is in the act of flying through air such as friction and so forth. Read in detail about these forces as follows.

Weight

Needless to say the airplane is a gigantic piece of machinery having a lot of weight. We know that weight always acts downwards towards the earth due to the force of gravity and hence tends to push the object down. Were it not for the engines the plane would simply fall flat on the ground. The weight of the aircraft is also acting while it is on ground hence it is a fixed force (as long as the load is not changed) which is present irrespective of the fact whether the airplane is flying or standing on the ground.

Lift

So if gravity tends to push an object downwards, what holds the airplane in air? Well it is another force which is rightly known as “lift” since it keeps the aeroplane lifted in the air. We can imagine intuitively that for an aircraft to not fall down, the lift should be at least equal to the weight if not more. If the lift is equal the airplane will stay at a particular height while if the lift is increased it will increase the height of the airplane relative to the ground as well.

Drag

Try to do a simple experiment, swing your arm in air and them try to move it at the same speed through a tub filled with water. You can notice the change is resistance to your movement. Even when you are traveling on your bike you can feel the force with which the air is resisting your motion. This force is known as drag and opposes the movement of any object through a fluid. The force of drag is not fixed but varies with the speed of the vehicle, other parameters remaining constant.

Thrust

Just as a lift force is required to lift the airplane and keep it floating in air, a thrust force is required to counter the effect of drag force and keep it moving with a particular speed in air.

The Combination of all 4 Forces

Forces on an Airplane
click to enlarge
The figure to the left shows all these four forces acting on the body of an airplane with their directions as well. Now the next question is that weight and drag can be considered to be naturally occurring forces in that you do not have to do anything to create them. Of course they can be varied by changing the load and shape of the airplane respectively but the main worry of an aeronautic engineer is to find out ways to create lift and thrust. This is done with the help of machinery such as propellers, jet engines and so forth and is a subject matter of separate discussion in detail.


Comments

Showing all 13 comments
 
hamayon Feb 21, 2011 6:43 AM
hi
i am hamayon form greek afg i wan to learn about air and to make small air palne what i do please.
Damen Nov 11, 2010 7:50 AM
Concerning Lift.
Hey now, Lift does not increase in a steady state climb, it actually decreases due to the inclined thrust vector. The engine is providing some of the 'up' force. For most flight conditions the lift will remain constant, exactly canceling out gravity.
Issa Nuru Nov 8, 2010 2:18 AM
In case of Accident
Do you have a mechanism that will resist an air craft into burning?
Gabriel Jun 8, 2010 6:28 PM
PLANE AGAINST GRAVITY
Hi,

Please, help me with this question: Why is it that an aeroplane does not obey gravity.
Mitchel Eisenstein May 13, 2010 12:07 PM
Actual G's experienced in level flight at constant speed
You know i have a question about the forces which act on a person during flight. When I travel on an airliner at 30,000 feet cruising at 587 mph, and I get up to walk to the bathroom, it feels heavier than walking on the ground. It feels as if there are more G's acting on me than if I were walking alone. I know that Newtons law says that objects in motion tend to stay in motion and act as if they are at rest in that motion, but i am wondering that if the plane is actually not coasting but being constantly pushed/pulled upward in order to stay aloft, combined with the speed it is traveling in some way, causes the amount of G forces to be increased? I am talking level flight here! Or is it perhaps because of the decreased air pressure in the pressurize cabin, that gives one the sensation of more G's? I really would like to get to the bottom of this!
umeimah Apr 22, 2010 10:26 AM
which forces????/
which act on an aeroplane
emily Feb 9, 2010 11:42 AM
how do they all work ?
how do all the forces work at the same time ????
mike smith Dec 16, 2009 8:27 PM
fuel consumption
how much fuel would a plane consume if it weighs 10 tons for 3 hours
Nuru Issa Nov 27, 2009 7:16 AM
Fuel Consuption
I think the plane maker have to think on fuel consuption as I know the fuel used is alot as compared to the plane natural largeness and its archtect work on it.
what do you think?
mamun Oct 29, 2009 6:07 PM
aeronautics
Hello,
How many types of drags do work when an aeroplane fly?
martha Sep 23, 2009 3:30 PM
REQUEST
hello!
how much does a aeroplane weigh?
Monisha Sep 9, 2009 8:05 PM
lift of a plane
how does a plane achieve lift???
Zaharadeen Aug 5, 2009 11:37 AM
REQUEST
hello!
the holderof this website please i need on how to produce an aeroplane
 
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