Definitions

1.1.1 Aerodynamics

It is the branch of science which studies the forces and moments necessary to have a controlled and sustainable flight in air. These forces are named the lift in the direction normal to the flight and the drag or the propulsive force in the direction of the flight. In addition, it studies the effect of the velocity fields induced by the motion during flight. On the other hand, the study of the forces created by the motion of an arbitrarily shaped body in any fluid is the concern of the Fluid Mechanics in general. It is necessary to make this distinction at this stage.

1.1.2 Aerodynamic Coefficients

These are the non-dimensional values of pressure, force and moment which affect the flying object. In non-dimensionalization, the free stream density p and the free stream velocity U are used as characteristic values. One half of the dynamic pressure, VipU2 is utilized in obtaining pressure coefficient, cp. As the character­istic length, half of the chord length and as the characteristic area the wing surface area are considered. Hence, the product of dynamic pressure with the half chord is used to obtain the sectional lift coefficient q, the drag coefficient cd, and the moment coefficient cm, wherein the square of the half chord is used. For the finite wing, however, the coefficient of lift reads as CL, the drag CD and the moment coefficient CM.