WHAT ARE THE FORCES ACTING ON AN AIRCRAFT ?

INTRODUCTION

An aircraft is proof that gives the will; we can achieve the impossible. Four forces will act on an aircraft to fly. They are thrust, drag, lift, and weight. These forces control the motion of the aircraft during flight.

These forces allow an aircraft to take off, cruise and land. When describing these forces we have to consider the magnitude and direction.

1. lIFT

In order for an aircraft to rise into the air, a force must be created that equals or exceeds the force of gravity. This force is called lift. The lift will act opposite to weight created due to difference in air pressure.

In one sentence, wings make lift by changing the direction and pressure of the air that crashes into them as the engine shoots them through the sky.

Lift force depends on many factors as well such as aerodynamics, size, and velocity of an aircraft. Most of the lift is actually generated by wings, and wings are specially designed for this purpose. Lift is an upward force.

2. DRAG

Every physical body that is propelled through the air will experience to the airflow. This resistance is called drag. Drag is a result of a number of physical phenomena. Drag which will act opposite to thrust created due to friction as well as the difference in air pressure.

Like lift, drag is proportional to dynamic pressure and the area on which it acts. Aircraft's efficiency increases as drag decreases. An aircraft's wing is designed to be smooth in order to reduce drag.

Pressure drag is that which you feel when running on a windy day. The pressure of the wind in front of you is greater than the pressure of the wake behind you. A rough surface will induce more frictional drag than a smooth surface.

3. WEIGHT

Weight is a force that is always directed toward the center of the earth. It is a downward force and is distributed throughout the aircraft like payload, fuel, and parts of an airplane. It is directed downwards on all parts but we use the center of gravity as a point for total weight.

The weight which will act opposite to lift created due to the difference in air pressure. In order for an aircraft to stay level, weight should be equal to lift. Weight and lift are the same when an aircraft flies at a constant velocity.

Because excess weight requires more lift, and therefore more thrust. Heavy aircraft are more difficult to get off the ground as compared to lighter aircraft. Aircraft with less weight requires less thrust. Thus, planes are designed to be as light as possible.

4. THRUST

Thrust is produced by a propulsion system or an engine to make an aircraft forward. The force depends on how the engine is attached to an aircraft but it will always be used to push aircraft move in a forward direction.

The magnitude of thrust depends on many factors such as the number of engines, type of engines, and also throttle settings in an aircraft. Thrust is a force that helps an aircraft move forward.