Forces Acting on an Airplane in Flight

There are 4 main forces that affect an airplane in flight, these forces are:

1. Thrust: “Provides the forward motion of an airplane created by the backward force created by the engines and its propeller(s).” (MacDonald, 2000)

2. Drag: The resistance to forward motion directly opposed to thrust. There are two principal types of drag parasite and included. Parasite drag is any type of resistance from parts of the aircraft that do not contribute to lift such as the fuselage, landing gear or antennas. Induced drag is caused by parts of the aircraft that are active in producing lift mainly being the wings.

3. Lift: The force upward which sustains the airplane in flight. Lift is created when an airfoil (or wing) is introduced into a streamlined airflow. The air must travel a further distance over the top of the wing than over the lower edge of the wing, to compensate for this further distance the air must then increase thus reducing its pressure (See: Why is Bernoulli’s Principle is Important to Aerodynamics?). The air flowing underneath the wing also does not just flow rearward but also flows downward as well also creating additional lift.

4. Weight: The downward force due to gravity which directly opposes lift. Weight is simply attributed by the weight of the aircraft, and all of its contents and components.

For further information on the 4 forces and how they affect flight please visit this slideshow at http://www.planemath.com/activities/pmenterprises/forces/forces2.html
This link contains a page with many useful sites relating to Aerodynamics: http://www.dmoz.org/Science/Technology/Aerospace/Aeronautics/Aerodynamics/