Principle Of Flight, Forces

When an aircraft is flying, there is 4 forces which is acting on it. These are Thrust, Drag, Lift and Weight. Thrust is couple by Drag. While Weight is couple by Lift. These are the forces which makes the plane fly straight and level when T = D, L = W.

However its not as simple as it thinks. There is other factors which play a roles as well. Newton's Law of Motion, Bernoulli's principle of pressure, Center of Gravity (CoG) and Airframe or Aircraft Structure Design.

When an aircraft is flying, its never be as prefect as theory is stated. There is always flaw in every design. Every designer always try to minimize all these flaw as much as possible.

Thrust is created by engines which could be either piston or turbines engine.

Drag is divided into 2 category which is induced drag and profile drag. Profile drag is proportion to speed, and induced drag is inverse proportion to speed. When both line meet in a graph, the point where they meet is VIMD where the drag is minimum. Drag is caused by the wake turbulence if the air flow is not laminar and friction between air and aircraft.

Weight is caused by gravity and the mass of the aircraft.

Lift is created by aerodynamic pressure using Bernoulli's principle on the airfoil of the wing. A differential pressure will cause the force to move from a higher pressure area to the lower pressure area.

*This is a summarized version. If you wish to know more, you can check out at Pilot's Web