Question

In the NACA 64-212 designation, the third digit indicates

• A. Design Lift Coefficient
• B. Location of Minimum Pressure
• C. Maximum Thickness
• D. Location of thickness

Hint:

For NACA 6-series airfoils, \[ \boxed{ \begin{aligned} \text{1st digit} &\rightarrow \text{Series} \text{2nd digit} &\rightarrow \text{Location of minimum pressure} \text{3rd digit} &\rightarrow \text{Design lift coefficient} \text{Last two digits} &\rightarrow \text{Maximum thickness (\% chord)} \end{aligned} } \]

Answer 1

The Correct Option is A

Step 1: Recall the NACA 6-series airfoil designation. For a NACA 6-series airfoil, \[ \boxed{\text{NACA }6x\text{-}abc} \] where
• First digit (\(6\)) denotes the 6-series airfoil.
• Second digit indicates the location of minimum pressure.
• Third digit indicates the design lift coefficient.
• Last two digits indicate the maximum thickness as a percentage of the chord.

Step 2: Interpret NACA 64-212. For \[ \boxed{\text{NACA }64\text{-}212,} \] the third digit \[ \boxed{2} \] represents the design lift coefficient. Therefore, \[ \boxed{\text{Design Lift Coefficient}} \] is the correct answer. Thus, \[ \boxed{(A)} \] is the correct answer.