hello and welcome to jxj aviation in this video we will be looking at what is an airfoil and different terms and definitions associated with an airfoil what is an airfoil the cross-sectional shape of an aircraft swing is called an airfoil the airfoil is primarily responsible to generate lift force which acts perpendicular to the direction of the airflow lift force is created because of a pressure difference between the upper and the lower surface of the airfoil on the upper surface of the airfoil the flow is faster than the flow in the lower surface so the air pressure over the top surface of the airfoil is less than the air pressure under the bottom surface of the airfoil this creates the lift force the lift depends on the shape of the airfoil velocity density of air surface area angle of attack of the airfoil now let's look at some terms and definitions associated with an airfoil leading edge the section of the airfoil which hits the air first trailing edge the section of the airfoil which hits the air last chord the distance between the leading and the trailing edge chord line a straight line joining the leading and the trailing edge camber line a line joining the leading and trailing edge of an airfoil and equidistant from the top and bottom surfaces distance from the camber line to the cord line thickness distance from the top surface to the bottom surface leading edge radius the radius of curvature at the leading edge if we consider an airfoil moving across a fluid we can see a few more terms pitching moment the torque or twisting force created on an airfoil by the aerodynamic force is acting on it center of pressure a point on the airfoil where the resultant lift vector can be considered to be acting here the pitching moment is zero aerodynamic center point where the pitching moment is constant and independent of the angle of attack and lift coefficient angle of attack the angle between the relative wind and the cord line an increase in the angle of attack results in an increase in the lift straw a condition in which the lift suddenly decreases and the drag increases because of an increase in the angle of attack stall angle the angle of attack at which stall occurs types of airfoils symmetric airfoil the upper and lower surfaces of this airfoil are identical the cord line and camber line are the same non-symmetric airfoil the upper and lower surfaces of this airfoil are different the cord line and camber line are different they are also called as cambered airfoils if the camber line is above the cord line the lift is generated upward if the camber line is below the cord line the lift is generated downward thank you for watching if you liked the video please subscribe [Music]