1) Kind of airfoil
2) Forces acting on the aircraft
1.Kind of airfoil
A structure having a shape that provides lift, propulsion, stability, or directional control in a flying object. An aircraft wing provides lift by causing air to pass at a higher speed over the wing than below it, resulting in greater pressure below than above. Propellers are airfoils that are spun rapidly to provide propulsion. See more at Bernoulli effect, See Note at aerodynamics. The distribution of lift around the aircraft is important for solving the control problem. Aerodynamic surfaces are used to control the aircraft in roll, pitch, and yaw. A fixed-wing aircraft's wings, horizontal, and vertical stabilizers are built with airfoil-shaped cross sections, as are helicopter rotor blades. Airfoils are also found in propellers, fans, compressors and turbines. Sails are also airfoils, and the underwater surfaces of sailboats, such as the centerboard and keel, are similar in cross-section and operate on the same principles as airfoils.