This calculator multiplies five selected dimensionless factors and compares the result with a selected fixed reference value of 1.50. It does not predict the maximum lift coefficient of an aircraft or determine a flap design.
Slotted Flap · Factor Calculator
Explore a hinged slotted flap and compare selected dimensionless factors.
Equation Used
- All five inputs are selected arithmetic factors, not validated aerodynamic coefficients.
- The fixed comparison reference is 1.50.
- Separate reference bars and a triangle show the selected chord ratio and sweep angle. The flap shape and hinge dimensions are illustrative.
- Airfoil, Reynolds and Mach numbers, deflection, gap, overlap, roughness, drag, moment, loads and safety are excluded.
The fixed 1.50 value is an arithmetic comparison. The animation illustrates a flap pivoting below its lower surface.
Illustrative slotted-flap reference
The flap turns about a hinge beneath its lower surface, opening a passage between its nose and the fixed wing. A rigid support arm connects the flap to the hinge. Separate reference bars show the selected chord ratio, and a triangle shows the selected sweep angle.
What the calculator determines
Select factor Kf, chord ratio, base increment, flapped-area ratio and sweep. The calculator reports their exact product, the sum with a fixed 1.50 comparison, the ratio to that comparison and the cosine reduction.
Selected factor arithmetic
P=Kf·(c′/c)·B·A·cosΛ; comparison sum=1.50+P; relative gain=100P/1.50; cosine reduction=100(1−cosΛ).
Selected-input arithmetic
For Kf=1.00, c′/c=1.20, B=1.25, A=0.70 and Λ=25°, the selected product is about 0.95 and the fixed-reference sum is about 2.45.
Limits of the factor calculation
NASA/NACA test data show maximum lift depends on airfoil, flap size, position, slot shape, deflection, Reynolds number, roughness and other configuration details. None are solved by this product. Loads, pitching moment, drag, stall speed, mechanism design and safety are excluded.
Questions
Is the 1.50 reference a clean-wing prediction?
No. It is a fixed arithmetic comparison, independent of any particular airfoil.
Does Kf identify a certified flap type?
No. It is a selected factor only; no single/double/triple-slot performance is inferred.
References & Further Reading
FAA, Pilot’s Handbook of Aeronautical Knowledge, chapter 6, pages 6-8–6-9: hinged slotted flaps.
- Wikipedia contributors. Flap (aeronautics). Wikipedia
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