# What are the variables of the induced drag formula and where does this force apply?

I want to understand a little bit more the induced drag force, therefore in analyzing the formula: $$F_D = C_DA\frac{⍴V^2}{2}$$

what do the following variables actually mean?

$$F_D$$ Is the 3D induced drag. If we take this force as a vector, where should I place it? I've read in another post about the drag center, how can I calculate it if needed?

In addition, I would have to calculate the induced drag force taking only 1 wing's half, should I take the area of the wing's half

• You should link the "other post" you read. Otherwise, there is a high probability the answer will be the same and it will stay as blur as it is now for you. – Manu H May 29 at 6:09
• That is not the formula for induced drag, but rather for parasite (pressure+friction) drag. Induced drag is inversely proportional to dynamic pressure. The formula for induced drag is $D_i = \frac{L^2}{\frac{1}{2} \rho V^2 \pi b^2 e}$ where $L$ is lift, $b$ is wing span and $e$ is efficiency factor. Note that lift is constant in straight flight, so it is in practice really inversely proportional to dynamic pressure. Substituting for lift would cancel the dynamic pressure terms, but the inverse proportionality would just hide in $C_L$ variation. – Jan Hudec May 29 at 6:28