Forces Acting on an Airplane

There are only four forces acting on an airplane. As we go on you will know the four forces and understand some basics. Firstly all objects have mass and are attracted towards the earth(by gravity) , the measure of the force of attraction is called weight. Can you imagine a see-saw, now on this see-saw if you added 10kgs or 22 lbs on both sides what would happen? You would see that the see-saw balances it self. Like the see-saw an airplane has a balance point, where the total weight can be summed up and at which point it balances itself. This balance point is called Centre of Gravity (CG).

If you had an object or body which weighed 50 kg or 110 lbs, what does it mean? It means that the earth is pulling that body or object towards its center with a force of 50 kg or 110 lbs.  So, if this object needs to fly you would need a force equal or greater and opposite to weight. This force that opposes weight is called lift. But in an airplane lift cannot be generated without forward motion.Helicopters or Rotary wing aircraft’s work a little differently.

The propulsion required to propel an aircraft is known as thrust. There is a force that is a retarding force to thrust, its called drag.Drag is also created by lift. So, to overcome drag you need thrust.This is all that is required at a basic level, all you need to remember is  lift opposes weight and thrust opposes drag , below are the definitions of Thrust, Drag , Lift and Weight. Just try to understand them and in the lessons to come we will analysis each force one by one in detail. Do remember there are only four forces acting on an airplane, which oppose each other in level and un-accelerated flight :

1. Thrust : is the forward force produced by the engine or propeller. It opposes or overcomes the force of drag.

2.Drag : is a rearward force that opposes thrust and is caused by airflow around the fuselage and other protruding objects, a part of drag is generated by the airfoils.

3.Weight : is the measure of the force of  gravity which pulls the plane downwards towards the center of the earth. It opposes lift.

4.Lift :  opposes the downward force of weight and is produced by the difference in pressure on the upper and the lower surfaces of the airfoil.