Airfoil Trailing Edge Flap Lift Calculator

High-Lift Aerodynamics: Calculate flap effectiveness ($\tau$), lift coefficient increment ($\Delta C_L$), flapped $C_{L,max}$, and stall speed reduction.

Flap Geometry & Deflection

Flap Chord Ratio $c_f / c$:

Flap Deflection $\delta_f$ (°):

Flap Device Architecture:

Clean Airfoil Baseline

Clean Airfoil $C_{L,max}$:

Clean Stall Speed $V_s$ (kts):

Flapped High-Lift Output

Flapped Max Lift ($C_{L,max}$)

Lift Boost: +--

Flapped Stall Speed ($V_{s,flap}$)

-- kts

Reduction: --- %

Zero-Lift Shift ($\Delta\alpha_{L0}$)

-- °

Effectiveness Factor τ: --

Quarter-Chord Moment ($\Delta C_m$)

Nose-down trim penalty

Flap Aerodynamic Principles:

• $\Delta C_L = a_0 \cdot \tau \cdot \delta_f$: Deflecting the flap adds virtual aft camber, shifting $\alpha_{L0}$ to negative values.

• Fowler flaps translate aft before deflecting downward, extending wing reference chord and boosting $C_{L,max}$ up to $2.4$–$3.2$.

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Airfoil Trailing Edge Flap Lift Calculator

Flap Geometry & Deflection

Clean Airfoil Baseline

Flapped High-Lift Output

Frequently Asked Questions