In this post we will examine how and why aerodynamic forces are generated as the airplane moves through the air, and introduce a method to non-dimensionalize the forces such that aircraft of various shapes and sizes can be directly compared to one-another. If you have read the previous post you will understand that lift must be produced by the airplane wing in order to act as a counter-force to the total flying weight, and that as a natural consequence to the motion of the aircraft through the air, a drag force that opposes this motion is also present. Two of the four fundamental forces acting on an aircraft during flight come about as a result of the aerodynamic loading on the body as it flies through the air. We will look at the relationship between the two forces, study how they interact with one another, and learn how to non-dimensionalize the resulting forces. We are now going to look more closely at the two aerodynamic forces Lift and Drag. Mach number has been left at the default value of zero.In the previous post we introduced the four fundamental forces acting on an aircraft during flight: Lift, Drag, Thrust and Weight and examined how they interact with one-another. Ncrit value is used to model of the turbulence of the fluid or roughness of the airfoil.Ĭurrent repository contains data for average wind tunnel with Ncrit=9 Reynolds number range from 50,000 to 1,000,000 in approximatly logarithmic steps. Systems that operate at the same Reynolds number will have the same flow characteristics even if the fluid, speed and characteristic lengths vary. The Reynolds number is a dimensionless value that measures the ratio of inertial forces to viscous forces and descibes the degree of laminar or turbulent flow. a=1 is the default if no value is given.įor example, the NACA 612-315 a=0.5 has the area of minimum pressure 10% of the chord back, maintains low drag 0.2 above and below the lift coefficient of 0.3, has a maximum thickness of 15% of the chord, and maintains laminar flow over 50% of the chord.
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