Before I get into detail about aircraft structures and composites, let us address the general question, how do planes fly? There are four principles that determine whether a plane is able to fly. These four forces are lift, thrust, drag and weight. The shape of the wing is responsible when generating lift. The shape of the wing’s cross section is an airfoil. According to Bernoulli’s Principle, relative wind, the wind that passes over the wing, helps the airfoil generate lift by having high pressure flow through the bottom of the wing, forcing the plane up, while the low pressure flows over the top of the wing at a faster rate. The force of thrust is responsible for moving the aircraft forward. The propeller or the jet engine is responsible for generating thrust in order to propel the plane forward. Lift and thrust aid the plane in flying.

               The two other forces counteract lift and thrust and are responsible for encouraging engineers to keep innovating in order to reduce the influence of weight and drag to improve the efficiency of flight. The weight force is the force due to gravity, the gross weight of the plane, pulling the plane down. In order for a plane to fly, the lift force generated must be greater than the weight. The gross weight of a plane is composed of the payload, the amount of fuel, and the empty weight. If not enough lift is generated in order to be greater than the weight, an accident is waiting to occur. The force counteracting thrust is drag. Drag is formed from the aircraft’s existence due to the aircraft’s resistance to move through the fluid of air. The force of thrust must be greater than the force of drag in order for the plane to move forward. This is the general overview of how flight occurs.