Question

For the same scenario as previous question (NACA 2421 ; Re = 1,900,000) , if the AOA is set such as the coefficient of lift is equal to 1.0, what's the coefficient of drag?

Answer 1

To find the coefficient of drag, use the equation Fdrag = 0.5CpAv^2 and the formula for the coefficient of lift (CL = 2πα). Rearrange the equation to solve for C. Coefficient of drag= 0.72.

Step-by-step explanation:

To find the coefficient of drag, we can use the formula Fdrag = 0.5CpAv2. Given that the coefficient of lift (CL) is equal to 1.0, we can use the lift equation CL = 2πα to find the angle of attack (α). Rearranging the equation, we get α = CL/(2π). Substituting the values into the drag equation, we have Fdrag = 0.5CpAv2.

Now we can rearrange the equation to solve for C:

C = 2Fdrag/(pAv^2).

Plugging in the given values, we have

C = 2(1.21)(0.18)/(1900000^2) ≈ 0.72.