GATE 2023 AE – Question 27
Which of the following statement(s) is/are true about the ribs of an airplane wing with semi-monocoque construction?
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: (B) Ribs increase the column buckling stress of longitudinal stiffeners connected to them.; (C) Ribs increase plate buckling stress of the skin panels.; (D) Ribs help in maintaining aerodynamic shape of the wing.
Explanation
Think about what the ribs do in a semi-monocoque (skin, stringers and ribs) wing.
- **A. For a rectangular planform, rib dimensions do not depend on spanwise position.** False. The airfoil thickness and the loads can vary along the span (taper in thickness, local load concentrations), so the ribs are not all identical.
- **B. Ribs increase the column buckling stress of stringers.** True. They act as supports along the stringer length, reducing the effective column length. ✓
- **C. Ribs increase the plate buckling stress of the skin panels.** True. They reduce the panel length between supports. ✓
- **D. Ribs maintain the aerodynamic shape of the wing.** True. They give the wing its airfoil cross-section and keep the skin from distorting. ✓
Answer **B, C and D**.