CHANGE THE SHAPE. FOLLOW THE CONSEQUENCE.
Move the flap. Rebalance the aircraft. Watch lift capability, drag and tail load change together.
Drag to orbit · right-drag to pan · scroll to zoom. Flap rotation is prescribed; incidence shows the calculated trim demand. An unavailable lift margin means that this attitude is a required demand, not achieved attached-flow flight. The generic 12% section thickness is a visual aid; the lift model is thin-aerofoil based. A is amber; B is turquoise.
At fixed speed and weight, the tail and wing must still close both force and pitching-moment balances.
Whole-run summary · live values appear above
CAUSE → RESPONSE → COMPARISON
B · solid turquoise A · dashed amber
Time plots share the playback cursor. Design sweeps and phase plots retain their own axes. In this prescribed deployment, a non-positive lift-limit margin marks unavailable trim. Drag and incidence remain required demands, not a post-stall prediction.
| Whole-run quantity | A · saved | B · live | B − A | Unit |
|---|
A snapshot includes parameter values and event times. Export retains both configurations and their calculated traces.
THE PHYSICS BEHIND THE RESPONSE
Follow each balance, then connect it to the response above. Open Symbols & units for the notation. A dot denotes a time derivative unless a non-dimensional time is stated.
Flap deflection changes the zero-incidence lift. The finite-wing correction sets the lift-curve slope.
At fixed weight and speed, the wing and tail must satisfy force and pitching-moment equilibrium together.
This estimate includes the tail load required by the same pitching-moment balance. A negative pitching-moment coefficient requires a downward tail force and increases the wing lift demand. The assumed maximum lift is not a measured stall boundary.
After the event, the flap approaches its demand exponentially. Before the event it remains at zero deflection. Required trim is evaluated at each state; it is unavailable when the wing demand reaches or exceeds the declared lift limit.
Equations describe this bounded teaching model. Assumptions and source references are retained below. Internal calculations use SI units; controls and plots show their own labelled units.
Generic S = 24 m², b = 13 m, e = 0.8; tail area 5 m² and arm 5 m. Finite-wing lift-slope correction plus small-deflection, sealed-flap thin-aerofoil increments. CLmax = user clean limit + user flap gain × flap angle + 0.4 for the leading-edge device; the 0.4 increment is illustrative. CD0 = 0.025 + 0.000025δ² + 0.004 with slat + 0.018 with gear. No measured aircraft polar, runway calculation, flap asymmetry, slot flow or post-stall dynamics. Time history is quasi-steady trim, not a flight trajectory.
NACA Report 721 · Plain-flap theory and data ↗NACA Report 938 · High-lift devices ↗Numerical checks test the stated equations. They do not establish aircraft certification or experimental accuracy. Schematic flow markers indicate direction; their speed is illustrative. No manufacturer geometry or performance data is reproduced. Version: coupled-labs-v1.1.