Deploying trailing-edge Fowler flaps on a transport aircraft wing increases the maximum lift coefficient $C_{L,\max}$ primarily through:

(A) Increasing both the effective airfoil camber and the effective wing planform area

(B) Decreasing the wing aspect ratio while keeping chord constant

(C) Shifting the aerodynamic center rearward past the trailing edge

(D) Delaying transition by keeping the boundary layer fully laminar

Answer Key:

A

### 5-Stage Derivation & Analytical Solution: 1. **Stage 1: Kinematics of Fowler Flap:** Unlike plain or split flaps, Fowler flaps translate aft on tracks, increasing chord length $c$ and wing area $S$. 2. **Stage 2: Camber Addition:** The flap downward deflection increases mean camber line curvature, raising $C_L$ at any angle of attack. 3. **Stage 3: Aerodynamic Consequence:** Combined effect dramatically increases $C_{L,\max}$. 4. **Stage 4: Selection:** Option A is correct.

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