GATE 2022 AE – Question 26

Correct answer: (B) maximum camber at 40% chord; (C) 12% maximum thickness to chord ratio

Explanation

The **NACA 4-digit** series describes an airfoil by three numbers, for example 2412:

• **First digit (2):** maximum camber as a percentage of the chord, so **2%** camber.
• **Second digit (4):** the position of the maximum camber in tenths of the chord, so at **40%** of the chord.
• **Last two digits (12):** the maximum thickness as a percentage of the chord, so **12%** thick.

Check the options:
- A, 4% maximum camber: ✗ (it is 2%)
- B, maximum camber at 40% chord: ✓
- C, 12% thickness: ✓
- D, maximum camber at 20% chord: ✗

Answer **B and C**.