GATE_AE_2027_MOCK_03_Q40
GATE 2027 Aerospace Engineering All-India Master Mock 03 (Flight Dynamics, Controls & Space Trajectories)
NAT · 2 Marks
Aerodynamics & Fluid Mechanics • Airfoil & Wing Theory • Thin Airfoil Theory & Camber Effects
A cambered thin airfoil has a zero-lift angle of attack \alpha_{L=0} = -2.5^\circ. What is the section lift coefficient C_l when the airfoil is operated at an angle of attack \alpha = 3.5^\circ? (Take \pi \approx 3.1416, round off to two decimal places).
Answer Key:
0.66
Step-by-Step Verified Solution
### Solution: Effective angle of attack lpha_{eff} = lpha - lpha_{L=0} = 3.5^\circ - (-2.5^\circ) = 6.0^\circ. In radians: 6 * \pi / 180 = 6 * 3.1416 / 180 = 0.10472 rad. C_l = 2\pi lpha_{eff} = 6.2832 * 0.10472 ≈ 0.6579 ≈ 0.66. Correct: 0.66 (range 0.64 to 0.68).