drag coefficient with aspect ratio calculator

For very low speeds (< 200 mph) the compressibility effects are negligible. Otherwise, the prediction will be inaccurate. The drag coefficient contains not only the complex dependencies of object shape and inclination, but also the effects of air viscosity and compressibility. To correctly use the drag coefficient, we must be sure that the viscosity and compressibility effects are the same between our measured case and the predicted case. Air Viscosity and Compressibility Effects We can predict the drag that will be produced under a different set of velocity, density (altitude), and area conditions using the drag equation. When reporting drag coefficient values, it is important to specify the reference area that is used to determine the coefficient. As pointed out on the drag equation slide, the choice of reference area (wing area, frontal area, surface area, …) will affect the actual numerical value of the drag coefficient that is calculated. Through division we arrive at a value for the drag coefficient. In a controlled environment (wind tunnel) we can set the velocity, density, and area and measure the drag produced. This equation gives us a way to determine a value for the drag coefficient. The drag coefficient then expresses the ratio of the drag force to the force produced by the dynamic pressure times the area. The quantity one half the density times the velocity squared is called the dynamic pressure q. The drag coefficient Cd is equal to the drag D divided by the quantity: density r times half the velocity V squared times the reference area A. This equation is simply a rearrangement of the drag equation where we solve for the drag coefficient in terms of the other variables. The drag coefficient is a number that aerodynamicists use to model all of the complex dependencies of shape, inclination, and flow conditions on aircraft drag. Home > Beginners Guide to Aeronautics Drag Coefficient

Drag coefficient with aspect ratio calculator