===================================================== -------- COEFFICIENTS — SIMPLE POCKET COURSE -------- -- (Use with TComponent: HasAeroCoefficients=TRUE) -- ===================================================== • Coefficient Notes: > Coefficients (CLa, CL0, CD0, etc.) are multipliers shaping lift, drag, moments in real-time. - Dimensionless units, not percentages. > Formula: Force = 0.5 ρ V² S Coefficient (ρ=air density, V=speed, S=area). > Act like sliders: Ex, CLa~0.095 (F-16) boosts lift per AoA; CD0~0.02 cuts drag. > SF2 Use: Tweak coeffs in [LeftWing], [Fuselage] to tune flight feel dynamically. -------- (legend: -------- > FLIGHT DYNAMICS PARAMETERS α = AoA (angle of attack, deg): Angle between wing chord and relative wind. β = sideslip (deg): Angle of sideways slide relative to flight path. p = roll-rate (rad/s): Rate of rotation around longitudinal axis. q = pitch-rate (rad/s): Rate of rotation around lateral axis. r = yaw-rate (rad/s): Rate of rotation around vertical axis. S = wing area (m²): Reference surface area for lift/drag calculations. c̄ = MAC (mean aerodynamic chord, m): Average wing chord length. > AERODYNAMIC COEFFICIENTS (Force and Moment Multipliers) CL = lift coefficient: Total lift force multiplier (e.g., A-10’s CL rises in turns). CD = drag coefficient: Total drag force multiplier (e.g., F-100’s CD spikes with spoilers). Cm = pitching moment coefficient: Torque rotating nose up/down (e.g., F-4’s Cm balances pitch). Cl = rolling moment coefficient: Torque rotating wings left/right (e.g., F-104’s Cl drives fast rolls). Cn = yawing moment coefficient: Torque rotating nose left/right (e.g., MiG-15’s Cn fights fishtailing). Cy = sideforce coefficient: Lateral force pushing plane sideways (e.g., A-10’s Cy stabilizes slips). > SUBSCRIPT MODIFIERS (Coefficient Conditions) a = vs. AoA (α): Effect tied to angle of attack (e.g., CLa for lift slope). 0 = at zero AoA: Baseline effect at α=0° (e.g., CL0 for camber lift). dc = delta control: Change per degree of control surface deflection (e.g., Cldc for aileron roll). b = vs. sideslip (β): Effect from sideslip angle (e.g., Cnb for yaw stability). p = vs. roll-rate (p): Effect from roll rate (e.g., Clp for roll damping). q = vs. pitch-rate (q): Effect from pitch rate (e.g., Cmq for pitch damping). r = vs. yaw-rate (r): Effect from yaw rate (e.g., Cnr for yaw damping). α̇ = vs. AoA-rate: Effect from rate of AoA change (e.g., Cmad for pitch damping). ----------------------------------------------------------------------------------------- HOW TO THINK ABOUT THEM (10-sec mental model) • Forces = 0.5·ρ·V²·S × (coefficients) • Coefficients are your “knobs” for lift/drag/stability. • Set real geometry in [AircraftData]; use these to shape behavior. ==================================================================== -------------------------------------------------------------------- ------------------ BASE COEFFICIENTS (LIFT / DRAG) ----------------- -------------------------------------------------------------------- ==================================================================== ------------------------------------------------------------------- CLa — Lift-curve slope (dCL / dα): how fast CL rises with α | Float ------------------------------------------------------------------- • Desc: > This is the primary lift-generating power of an aerodynamic surface. > It defines how quickly the Coefficient of Lift (CL) increases as the AoA (α) increases. • Real-World Examples & Analogy: > Wings types situations: - Straight wing (e.g., A-10): Stable lift buildup, lower CLa for steady flight. – Swept / Delta (e.g., F-100, Mirage): CL can rise quickly at low – mid α; if CLmax is similar, you reach CLmax at a lower α, so stall occurs at a lower AoA. Actual stall still depends on CLmax and (stall) tables. > Like wing horsepower: high-performance glider (high CLa) soars easily; flat board (low CLa) barely lifts. • Behavior: > Higher CLa = more lift per α degree, agile turns / climb > Lower CLa = stable but less responsive. > Value Effects: - Positive: Boosts lift, improves maneuvers (normal for wings). - Zero: No lift from α, plane unflyable. - Negative: Downforce, reverses pitch, unstable. • Limits / Tuning: > 0.09–0.11 → Agile fighters (e.g., F-16, tight turns). > 0.05–0.08 → Stable bombers / trainers (e.g., A-10, low stall speed). > 0.0 → No lift. • Components: > Primary: [Wing], [HorizontalTail] (main lift surfaces). > Secondary: [Fuselage] (body lift in fighters like F-16). > Usually 0.0: [VertTail] (no lift design). • Interactions: > The total lift force is scaled by the ReferenceArea from [AircraftData]. > The CLa slope is effective only until the AoA reaches AlphaStall, at which point the lift is limited by CLmax. > Ties to CDL (more lift = more induced drag). • Situation Example: > F-100 struggles in turns: Increase CLa to 0.09 on [Wings] for better lift / maneuverability • NOTE: It is critical to understand the difference between these terms. > CL is the current Coefficient of Lift, which changes constantly in flight. > CLa is the slope or "power" that determines how fast CL changes with AoA. > CLmax is the maximum possible value for CL. A stall occurs when the current CL reaches CLmax. > A slope (CLa) cannot "meet" a maximum value (CLmax). -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- CLa=0.065 ; --- CLa vs. Mach Table --- CLaMachTableNumData=9 CLaMachTableStartX=0.0 CLaMachTableDeltaX=0.25 CLaMachTableData=1.0, 1.05, 1.1, 1.15, 1.05, 0.85, 0.8, 0.75, 0.7 // This translates to: // At Mach 0.0, CLa multiplier is 1.0 (Effective CLa = 0.065) // At Mach 0.25, CLa multiplier is 1.05 (Effective CLa = 0.06825) // At Mach 0.5, CLa multiplier is 1.1 (Effective CLa = 0.0715) // At Mach 0.75, CLa multiplier is 1.15 (Effective CLa = 0.07475, transonic rise) // At Mach 1.0, CLa multiplier is 1.05 (Effective CLa = 0.06825, peak) // At Mach 1.25, CLa multiplier is 0.85 (Effective CLa = 0.05525, drop) // At Mach 1.5, CLa multiplier is 0.8 (Effective CLa = 0.052, reduction) // At Mach 1.75, CLa multiplier is 0.75 (Effective CLa = 0.04875) // At Mach 2.0, CLa multiplier is 0.7 (Effective CLa = 0.0455, supersonic reduction) ──────────────────────────────────────────────────────────────────── ------------------------------------------------------ CL0 — Baseline lift at α=0° (camber/trim bias) | Float ------------------------------------------------------ • Desc: > Lift (CL) at zero α, from airfoil camber (curved shape). • Real-World Examples & Analogy: > Cambered vs. symmetric airfoil: - Cambered wing (e.g., F-4): Positive CL0, built-in lift, nose-down Cm0. - Symmetric wing (e.g., F-16 aerobatic): Zero CL0, no bias, good for inverted flight. > Analogy: - Curved wing shape (camber) speeds air over top for low pressure "suck," creating lift like air pushing a sail—flat symmetric airfoil needs α for lift. • Behavior: > Positive CL0: Natural lift at level flight, easier cruise (cambered wings). > Zero CL0: No lift without α, symmetric, no bias (aerobatics). > Negative CL0: Downforce, nose-down bias (stabilizers). • Limits / Tuning: > 0.10–0.15 → Cambered fighters (e.g., F-4, cruise lift). > 0.0 → Symmetric aerobatics (e.g., F-16, inverted flight). > Negative → Downforce tails (e.g., -0.05, stabilizes pitch). • Components: > Primary: [Wing] (cambered lift). > Secondary: [HorizontalTail] (incidence angle). > Usually 0.0: [VertTail], [Fuselage] (symmetric). • Interactions: > Ties to Cm0 (positive CL0 = negative Cm0 nose-down) - Affects trim speed • Situation Example: > You're modeling a WWII fighter that feels "dead" and requires constant back-pressure on the stick to stay level. By giving its wings a small positive CL0 (e.g., 0.12), you simulate the lift from its cambered airfoil, making it fly more naturally at cruise speeds. • Note: > This key models the effect of the airfoil's shape. > Lift generated from the wing's mounting angle on the fuselage (angle of incidence) is handled separately by the geometry of the 3D model. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- CL0=0.05 ; --- CL0 vs. Mach Table --- CL0MachTableNumData=9 CL0MachTableStartX=0.0 CL0MachTableDeltaX=0.25 CL0MachTableData=1.0, 1.0, 1.0, 0.9, 0.8, 0.6, 0.5, 0.4, 0.3 // This translates to: // At Mach 0.0, CL0 multiplier is 1.0 (Effective CL0 = 0.05) // At Mach 0.25, CL0 multiplier is 1.0 (Effective CL0 = 0.05) // At Mach 0.5, CL0 multiplier is 1.0 (Effective CL0 = 0.05) // At Mach 0.75, CL0 multiplier is 0.9 (Effective CL0 = 0.045) // At Mach 1.0, CL0 multiplier is 0.8 (Effective CL0 = 0.04, transonic effect) // At Mach 1.25, CL0 multiplier is 0.6 (Effective CL0 = 0.03) // At Mach 1.5, CL0 multiplier is 0.5 (Effective CL0 = 0.025) // At Mach 1.75, CL0 multiplier is 0.4 (Effective CL0 = 0.02) // At Mach 2.0, CL0 multiplier is 0.3 (Effective CL0 = 0.015, supersonic reduction) ──────────────────────────────────────────────────────────────────── ------------------------------------------------ CD0 — Zero-lift (parasite) drag baseline | Float ------------------------------------------------ • Desc: > Constant drag from a component’s shape, size, and surface roughness, even when no lift is made. > All parts (wings, fuselage, tail) add to total drag, no matter AoA. • Real-World Examples & Analogy: > Sleek vs. blunt fuselage: - Sleek (e.g., F-104): Low CD0, high speed. - Blunt (e.g., A-10): Higher CD0, rugged but draggy. > Analogy: Brick (high CD0, blunt resistance) vs. sports car (low CD0, streamlined flow). • Behavior: > Baseline drag grows with V²; sums from all parts. > Value Effects: - Positive: Increases resistance, lowers speed (normal for all parts). - Zero: No drag, unrealistic. • Limits / Tuning: > 0.01–0.02 → Sleek fighters (e.g., F-104, high speed). > 0.03–0.05 → Rugged attackers (e.g., A-10, more drag). > High (0.06+) → Gear/stores, slows plane. • Components: > Primary: [Fuselage], [Wing] (main drag sources). > Secondary: [Tail], [Pylon] (add-ons like gear). • Interactions: > This is the baseline drag to which CDL (induced drag) is added to get the component's total drag. > Its effect is modified at high speeds by the CD0MachTable. • Situation Example: > Plane can't reach top speed: Lower CD0 0.02 on [Fuselage]/[Wings] for less drag. • Note: > This represents the drag of the "clean" component. > Drag from deflected control surfaces, deployed landing gear, and external weapons is calculated separately and added on top of this. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- CD0=0.016 ; --- CD0 vs. Mach Table --- CD0MachTableNumData=9 CD0MachTableStartX=0.0 CD0MachTableDeltaX=0.25 CD0MachTableData=1.0, 1.0, 1.05, 1.2, 1.5, 2.5, 2.0, 1.8, 1.6 // This translates to: // At Mach 0.0, CD0 multiplier is 1.0 (Effective CD0 = 0.016) // At Mach 0.25, CD0 multiplier is 1.0 (Effective CD0 = 0.016) // At Mach 0.5, CD0 multiplier is 1.05 (Effective CD0 = 0.0168) // At Mach 0.75, CD0 multiplier is 1.2 (Effective CD0 = 0.0192, transonic rise) // At Mach 1.0, CD0 multiplier is 1.5 (Effective CD0 = 0.024, peak spike) // At Mach 1.25, CD0 multiplier is 2.5 (Effective CD0 = 0.04, massive transonic drag) // At Mach 1.5, CD0 multiplier is 2.0 (Effective CD0 = 0.032, drop) // At Mach 1.75, CD0 multiplier is 1.8 (Effective CD0 = 0.0288) // At Mach 2.0, CD0 multiplier is 1.6 (Effective CD0 = 0.0256, supersonic reduction) ──────────────────────────────────────────────────────────────────── ------------------------------------------------------------ CDL — Induced/α-related drag (drag from making lift) | Float ------------------------------------------------------------ • Desc: > Drag from generating lift, caused by wingtip vortices as AoA or flaps increase. > Extra lift (e.g., flaps for takeoff/landing) adds more drag (CDL). • Real-World Examples & Analogy: > Low vs. high aspect ratio (AR) wings: - Aspect ratio (AR) affects efficiency: • High AR (long, narrow wings like A-10 attacker) cuts induced drag (low CDL) for better glide and sustained maneuvers. • Low AR (short, stubby wings like F-104 fighter) boosts maneuverability but adds drag (high CDL), causing quick energy loss in turns. > Analogy: Hand out car window angled for lift—extra push-back (CDL) vs. flat (CD0). • Behavior: > Low at zero α (cruise) > high at high α (turns / landings) > flaps boost lift and CDL. > Value Effects: - Positive: Increases with CL², bleeds speed in maneuvers (normal for lifting surfaces). - Zero: No induced drag, unrealistic for wings. • Limits / Tuning: > 0.05–0.1 → Short-wing fighters (e.g., F-100, high bleed in turns). > 0.02–0.04 → Long-wing attackers (e.g., A-10, better retention). > High (0.1+) → Delta wings, quick slowdown. • Components: > Primary: [Wing], [HorizontalTail]: This "drag from making lift" is primarily generated by your main lifting surfaces. > Secondary: [Fuselage]: Only if it's also configured to produce body lift (CLa greater than 0). • Interactions: > ~ CL² / (π AR e); scaled by CDLAlphaTable; flaps add via CDdc / CLiftdc. • Situation Example: > Your modern fighter jet loses too much speed in a sustained, high-G turn. > To improve its sustained turn performance, you would lower the CDL value on its wing components. • Note: > This key is crucial for defining an aircraft's "instantaneous" vs. "sustained" turn performance. > An aircraft with high lift (CLa) but also high induced drag (CDL) might have a great instantaneous turn, but its poor energy retention will result in a bad sustained turn. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- CDL=0.03 ; --- CDL vs. Alpha Table --- CDLAlphaTableNumData=9 CDLAlphaTableStartX=0.0 CDLAlphaTableDeltaX=2.0 CDLAlphaTableData= 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 4.0, 4.8 // This translates to: // At 0 deg AoA, CDL multiplier is 1.0 (Effective CDL = 0.03) // At 2 deg AoA, CDL multiplier is 1.2 (Effective CDL = 0.036) // At 4 deg AoA, CDL multiplier is 1.5 (Effective CDL = 0.045) // At 6 deg AoA, CDL multiplier is 1.8 (Effective CDL = 0.054) // At 8 deg AoA, CDL multiplier is 2.2 (Effective CDL = 0.066) // At 10 deg AoA, CDL multiplier is 2.7 (Effective CDL = 0.081, rising fast) // At 12 deg AoA, CDL multiplier is 3.3 (Effective CDL = 0.099) // At 14 deg AoA, CDL multiplier is 4.0 (Effective CDL = 0.12, near stall) // At 16 deg AoA, CDL multiplier is 4.8 (Effective CDL = 0.144, massive drag) ==================================================================== -------------------------------------------------------------------- ------------------ LONGITUDINAL (PITCH) STABILITY ------------------ -------------------------------------------------------------------- ==================================================================== ---------------------------------------------------------- Cm0 — Baseline pitching moment (nose-up/down bias) | Float ---------------------------------------------------------- • Desc: > Moment is also known as Torque or rotational force. > The component's natural tendency to pitch nose-up or nose-down at zero Angle of Attack, caused by its airfoil shape (camber). • Real-World Examples & Analogy: > Cambered vs. symmetric airfoil: - Cambered wing (e.g., F-4): Negative Cm0, nose-down bias from camber. - Symmetric wing (e.g., F-16 aerobatic): Zero Cm0, no pitch bias. > Analogy: Paper airplane folds for balance—camber causes nose-down moment like a seesaw tipping. • Behavior: > Negative Cm0 = Nose-down for stability, Stabilizes pitch (common for wings). > Zero Cm0: No bias (symmetric surfaces). > Positive Cm0: Nose-up tendency, unstable without counter. • Limits / Tuning: > -0.03 to -0.05 → Cambered fighters (e.g., F-4, balanced pitch). > 0.0 → Symmetric (e.g., F-16, easy inverted). > Positive → Canards (e.g., 0.02, nose-up trim). • Components: > Primary: [Wing] (camber source). > Secondary: [HorizontalTail], [Fuselage] (trim balance). • Interactions: > Counters CL0 (positive CL0 = negative Cm0); balances with tail downforce and CGPosition. - Example: F-4 Phantom II - F-4’s cambered wings create a nose-down pitching moment (Cm0~-0.03 to -0.05) at zero AoA. • Wingtip dihedral (~12° upward tilt) adds slight nose-up torque, tweaking Cm0. • Horizontal tail (stabilators, ~23° anhedral, 1–2° negative incidence) gives downforce (CL0<0), creating strong nose-up moment to counter Cm0. • Engines (J79s) tilted down ~3–5° add nose-up thrust torque, balancing Cm0 for level flight. • Situation Example: > After setting a realistic CGPosition, your aircraft still has a strong tendency to pitch up uncontrollably at high speed. > You can add a small negative Cm0 to the main wing to create a counteracting nose-down moment for better stability. • Note: > Ties to CL0: Camber lift causes nose-down Cm0. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- Cm0=-0.03 ; --- Cm0 vs. Alpha Table --- Cm0AlphaTableNumData=9 Cm0AlphaTableStartX=0.0 Cm0AlphaTableDeltaX=2.0 Cm0AlphaTableData=1.0, 1.0, 0.9, 0.8, 0.6, 0.4, 0.3, 0.2, 0.1 // This translates to: // At 0 deg AoA, Cm0 multiplier is 1.0 (Effective Cm0 = -0.03) // At 2 deg AoA, Cm0 multiplier is 1.0 (Effective Cm0 = -0.03) // At 4 deg AoA, Cm0 multiplier is 0.9 (Effective Cm0 = -0.027) // At 6 deg AoA, Cm0 multiplier is 0.8 (Effective Cm0 = -0.024) // At 8 deg AoA, Cm0 multiplier is 0.6 (Effective Cm0 = -0.018) // At 10 deg AoA, Cm0 multiplier is 0.4 (Effective Cm0 = -0.012, weakening) // At 12 deg AoA, Cm0 multiplier is 0.3 (Effective Cm0 = -0.009) // At 14 deg AoA, Cm0 multiplier is 0.2 (Effective Cm0 = -0.006, near stall) // At 16 deg AoA, Cm0 multiplier is 0.1 (Effective Cm0 = -0.003, almost gone) ──────────────────────────────────────────────────────────────────── ---------------------------------------------- Cmq — Pitch-rate damping (moment vs q) | Float ---------------------------------------------- • Desc: > The primary pitch damping force. It creates a pitching moment that opposes the rate of pitching motion. > Acts like a "shock absorber" for pitch axis. • Real-World Examples & Analogy: > horizontal tail / Canards: - Large stabilators (e.g., F / A-18C / D): High Cmq, stable in high-AoA dogfights / landings. - Canards (e.g., Mirage III): Boost Cmq for smoother high-AoA pitch. Canard is desigend as damper for both Cmq and Cmad. > Analogy: Arrow fletching damps wobble for steady flight—larger fletching (tail) = stronger damping. • Behavior: > Negative Cmq reduces oscillation after input, stabilizing pitch. > Value Effects: - More negative: Smoother, stable pitch (less slippery). - Less negative: Responsive but Pilot Induced Oscillation (PIO) risk). - Zero: No damping, unstable wobble. • Limits / Tuning: > -0.4 to -0.6 → Stable fighters (e.g., F / A-18, smooth pitch). > -0.2 to -0.3 → Agile jets (e.g., F-16, quick response). > Less than -1.0 → Too stiff; > -0.1 → Bouncy. • Components: > Primary: [HorizontalTail] (main damping source). > Secondary: - [Wing]: Large wings, especially delta wings, also contribute to pitch damping. - [Canard]: Boosts Cmq in canard-equipped jets (e.g., Mirage III), improving high-AoA stability. • Interactions: > This is the primary force that counteracts the pitch axis of EmptyInertia. > The balance between inertia and damping defines pitch responsiveness. > Its effect can be modified at different speeds by the CmqMachTable. > The horizontal tail is the main contributor to an aircraft's Cmq. A larger tail produces a larger (more negative) Cmq. • Situation Example: > After you pull back on the stick and then return it to neutral, the aircraft's nose pitches down, then up, then down again before settling. To fix this oscillation, you would make Cmq more negative on the [HorizontalTail] component. • Note: > Supplements Cmad for rapid AoA changes; key for PIO prevention. Example: F-16A ~ -0.28. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- Cmq=-0.25 ; --- Cmq vs. Mach Table --- CmqMachTableNumData=9 CmqMachTableStartX=0.0 CmqMachTableDeltaX=0.25 CmqMachTableData=1.0, 1.0, 0.95, 0.85, 0.75, 0.7, 0.8, 0.9, 1.0 // This translates to: // At Mach 0.0, Cmq multiplier is 1.0 (Effective Cmq = -0.25) // At Mach 0.25, Cmq multiplier is 1.0 (Effective Cmq = -0.25) // At Mach 0.5, Cmq multiplier is 0.95 (Effective Cmq = -0.2375) // At Mach 0.75, Cmq multiplier is 0.85 (Effective Cmq = -0.2125, transonic weakening) // At Mach 1.0, Cmq multiplier is 0.75 (Effective Cmq = -0.1875, minimum damping) // At Mach 1.25, Cmq multiplier is 0.7 (Effective Cmq = -0.175, drop) // At Mach 1.5, Cmq multiplier is 0.8 (Effective Cmq = -0.2, recovery start) // At Mach 1.75, Cmq multiplier is 0.9 (Effective Cmq = -0.225) // At Mach 2.0, Cmq multiplier is 1.0 (Effective Cmq = -0.25, supersonic stability) ──────────────────────────────────────────────────────────────────── ------------------------------------------- Cmad — Pitch moment vs AoA-rate (α̇) | Float ------------------------------------------- • Desc: > A secondary pitch damping force related to the rate of change of Angle of Attack (how quickly AoA is increasing or decreasing). • Real-World Examples & Analogy: > Large vs. small horizontal tail: - Large tail (e.g., F-14): Strong Cmq, stable in carrier landings. - Canards (e.g., Viggen): Boost Cmq for quick high-AoA pitch. Canard is desigend as damper for both Cmq and Cmad. - Small tail (e.g., F-100): Weak Cmq, bouncy and unstable in maneuvers. > Analogy: Race car shock reacting to bump speed, beyond main spring (Cmq). • Behavior: > Damps rapid AoA changes (e.g., turbulence, abrupt sticks). > Value Effects: - More negative: Finer gust control. - Negative: Subtle damping, stabilizes quick pitch shifts. - Zero: No extra damping, rely on Cmq. • Limits / Tuning: > -0.3 to -0.5 → Gust-resistant (e.g., A-10, stable turbulence). > -0.1 to -0.2 → Responsive (e.g., F-16, quick AoA). > 0.0 → Minimal, expert only. • Components: > Primary: [HorizontalTail] (main damping source). > Secondary: - [Wing]: Large wings, especially delta wings, also contribute to pitch damping. - [Canard]: Boosts Cmq in canard-equipped jets (e.g., Mirage III), improving high-AoA stability. • Interactions: > This is the primary force that counteracts the pitch axis of EmptyInertia. > The balance between inertia and damping defines pitch responsiveness. > Its effect can be modified at different speeds by the CmqMachTable. > The horizontal tail is the main contributor to an aircraft's Cmq. A larger tail produces a larger (more negative) Cmq. • Situation Example: > Your aircraft is stable in smooth air, but in turbulent weather, its nose is constantly "twitching" up and down. Adding a small negative Cmad can help damp these rapid, AoA-induced oscillations without making the overall controls feel heavy. • Note: > Expert key; Cmq handles most damping. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [HorizontalTail] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- Cmq=-0.25 ; --- Cmq vs. Mach Table --- CmqMachTableNumData=9 CmqMachTableStartX=0.0 CmqMachTableDeltaX=0.25 CmqMachTableData=1.0, 1.0, 0.95, 0.85, 0.75, 0.7, 0.8, 0.9, 1.0 // --- Cmad (AoA-Rate Damping) --- // This is an expert-level key that supplements Cmq. It adds extra // pitch damping based on how quickly the Angle of Attack is changing. // It is useful for damping out rapid oscillations from turbulence or // very sharp stick inputs. Cmad=-0.05 ==================================================================== -------------------------------------------------------------------- ------------------- LATERAL STABILITY (ROLL AXIS) ------------------ -------------------------------------------------------------------- ==================================================================== ------------------------------------------------ Clb — Roll moment vs β (dihedral effect) | Float ------------------------------------------------ • Desc: > Roll moment from sideslip (β); plane’s natural wing-leveling tendency. - Sideslip: Plane slides sideways when nose doesn’t align with path. • Real-World Examples & Analogy: > Dihedral vs. anhedral wings: - Dihedral (upward V, e.g., F-86): Negative Clb, self-leveling in sideslips. - Anhedral (downward V, e.g., MiG-15): Positive Clb, snappy rolls but unstable. > Analogy: Upward V-shape (dihedral) makes lower wing lift more in sideslip, auto-leveling like a V-shaped boat stabilizing in waves. • Behavior: > In a sideslip (β), the windward / leading wing sees higher effective AoA, more lift. > If windward wing is low: Extra lift on the low (windward) wing → it rises → levels. > If windward wing is high: May rise a bit more briefly, then Slip + yaw stability shift wind to the low wing, leveling aircraft. > Value Effects: - Negative: Self-leveling (dihedral, stable). - Zero: Neutral (aerobatic, easy inverted). - Positive: Destabilizing (anhedral, agile). • Limits / Tuning: > -0.05 to -0.1 → Stable (e.g., F-86, self-leveling). > 0.0 → Aerobatic (e.g., F-16, neutral). > 0.01 to 0.05 → Agile (e.g., MiG-15, snappy). • Components: > Primary: [Wing] (dihedral / anhedral angle, high / low position). > Secondary: [VertTail] (small influence). • Interactions: > Its effectiveness can be modified by the ClbAlphaTable, often decreasing at high AoA. • Situation Example: > You are modeling a trainer aircraft that should be very stable. When you apply rudder and enter a sideslip, the wings don't level on their own. You would give the wings a negative Clb (e.g., -0.08) to create this self-leveling tendency. • Note: > Key for roll stability; sideslip (β) from rudder / crosswinds. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- Clb=-0.1 ; --- Clb vs. Alpha Table --- ClbAlphaTableNumData=9 ClbAlphaTableStartX=0.0 ClbAlphaTableDeltaX=2.0 ClbAlphaTableData=1.0, 1.0, 0.95, 0.85, 0.7, 0.5, 0.3, 0.2, 0.1 // This translates to: // At 0 deg AoA, Clb multiplier is 1.0 (Effective Clb = -0.1) // At 2 deg AoA, Clb multiplier is 1.0 (Effective Clb = -0.1) // At 4 deg AoA, Clb multiplier is 0.95 (Effective Clb = -0.095) // At 6 deg AoA, Clb multiplier is 0.85 (Effective Clb = -0.085) // At 8 deg AoA, Clb multiplier is 0.7 (Effective Clb = -0.07) // At 10 deg AoA, Clb multiplier is 0.5 (Effective Clb = -0.05, weakening) // At 12 deg AoA, Clb multiplier is 0.3 (Effective Clb = -0.03) // At 14 deg AoA, Clb multiplier is 0.2 (Effective Clb = -0.02, near stall) // At 16 deg AoA, Clb multiplier is 0.1 (Effective Clb = -0.01, almost gone) ──────────────────────────────────────────────────────────────────── --------------------------------------------- Clp — Roll-rate damping (moment vs p) | Float --------------------------------------------- • Desc: > The primary roll damping force. > Creates a rolling moment that opposes the rate of rolling motion (p). > Acts like a brake to slow or stop the aircraft’s roll after aileron input. • Real-World Examples & Analogy: > Long vs. short wings: - Long wings (e.g., A-10): High damping (more negative Clp), steady rolls. - Short wings (e.g., F-104): Low damping, snappy rolls. > Analogy: Truck steering resistance (high damping) vs. sports car nimbleness (low damping). • Behavior: > Stabilizes roll, settling at bank angle after input. > Value Effects: - More negative: Strong damping, crisp stops. - Less negative: Responsive but slippery. - Zero: No damping, continuous roll. • Limits / Tuning: > -0.5 to -0.8 → Stable (e.g., A-10, smooth rolls). > -0.2 to -0.4 → Agile (e.g., F-104, quick rolls). > > -0.1 → Slippery. • Components: > Primary: [Wing]? Roll damping is overwhelmingly determined by the wingspan and shape. > Secondary: [HorizontalTail], [VertTail]: The tail surfaces provide a small amount of additional roll damping. • Interactions: > This works in direct opposition to the ailerons' power (Cldc). > The balance between roll damping (Clp) and aileron power (Cldc) defines the final roll rate. > Its effectiveness can be scaled with the ClpAlphaTable. • Situation Example: > Your fighter jet rolls very fast, but it's difficult to stop the roll precisely. By making Clp more negative, you increase the roll damping, making the handling feel tighter and more precise. • Note: > Balance with Cldc for final roll rate. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- Clp=-0.24 ; --- Clp vs. Alpha Table --- ClpAlphaTableNumData=9 ClpAlphaTableStartX=0.0 ClpAlphaTableDeltaX=2.0 ClpAlphaTableData=1.0, 1.0, 0.95, 0.9, 0.8, 0.7, 0.5, 0.4, 0.3 // This translates to: // At 0 deg AoA, Clp multiplier is 1.0 (Effective Clp = -0.24) // At 2 deg AoA, Clp multiplier is 1.0 (Effective Clp = -0.24) // At 4 deg AoA, Clp multiplier is 0.95 (Effective Clp = -0.228) // At 6 deg AoA, Clp multiplier is 0.9 (Effective Clp = -0.216) // At 8 deg AoA, Clp multiplier is 0.8 (Effective Clp = -0.192) // At 10 deg AoA, Clp multiplier is 0.7 (Effective Clp = -0.168, weakening) // At 12 deg AoA, Clp multiplier is 0.5 (Effective Clp = -0.12) // At 14 deg AoA, Clp multiplier is 0.4 (Effective Clp = -0.096, near stall) // At 16 deg AoA, Clp multiplier is 0.3 (Effective Clp = -0.072, weak damping) ──────────────────────────────────────────────────────────────────── ------------------------------------------------------------------------------ Clr — Roll moment from yaw-rate r (roll–yaw coupling) | Cross-Coupling | Float ------------------------------------------------------------------------------ • Desc: > The rolling moment created by the aircraft’s yaw rate (r). > Drives roll due to yaw, contributing to Dutch roll oscillations. • Real-World Examples & Analogy: > Swept vs. straight wings: - Swept wing (e.g., MiG-15 / F-100): yaws left boosts right wing lift (less V-shaped), rolling left, worsening Dutch roll. - Straight wing (e.g., A-10): yaws left doesn’t change airflow much, minimal roll, no Dutch roll. > Analogy: Spinning frisbee yaw creating roll—swept wings amplify like a twisted disc wobbling. • Behavior: > yaws (nose swing) generates outer wing lift, causing roll in yaw direction. > Value Effects: - Higher Positive: More wobble (swept wings). - Positive: Amplifies coupling (common). - Zero: No roll from yaw. • Limits / Tuning: > 0.03–0.05 → Swept jets (e.g., F-100, Dutch roll risk). > 0.01–0.02 → Straight wings (e.g., A-10, stable). > 0.0 → No coupling, unrealistic. • Components: > Primary: [Wing]: This effect is caused by the speed difference between the outer and inner wing during a yaw. It is most pronounced on swept wings. > Secondary: [VertTail]: Can contribute a small amount. • Interactions: > Ties to Cnr / Cnb for damping Dutch roll; stronger in swept wings. • Situation Example: > You’re modding an F-100. After a rudder kick, it enters a rocking Dutch roll (yaw-roll wobble). - Reduce Clr on [Wings] and increase Cnr / Cnb on [VertTail] to damp the oscillation. > For an A-10, lower Clr ensures steady flight with less wobble. • Note: > Key for Dutch roll in swept jets; straight wings damp it naturally. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- Clr=0.035 ; --- Clr vs. Alpha Table --- ClrAlphaTableNumData=9 ClrAlphaTableStartX=0.0 ClrAlphaTableDeltaX=2.0 ClrAlphaTableData=1.0, 1.05, 1.1, 1.15, 1.1, 0.9, 0.7, 0.5, 0.3 // This translates to: // At 0 deg AoA, Clr multiplier is 1.0 (Effective Clr = 0.035) // At 2 deg AoA, Clr multiplier is 1.05 (Effective Clr = 0.03675) // At 4 deg AoA, Clr multiplier is 1.1 (Effective Clr = 0.0385) // At 6 deg AoA, Clr multiplier is 1.15 (Effective Clr = 0.04025, peak) // At 8 deg AoA, Clr multiplier is 1.1 (Effective Clr = 0.0385) // At 10 deg AoA, Clr multiplier is 0.9 (Effective Clr = 0.0315, weakening) // At 12 deg AoA, Clr multiplier is 0.7 (Effective Clr = 0.0245) // At 14 deg AoA, Clr multiplier is 0.5 (Effective Clr = 0.0175, near stall) // At 16 deg AoA, Clr multiplier is 0.3 (Effective Clr = 0.0105, minimal) ==================================================================== -------------------------------------------------------------------- ----------------- DIRECTIONAL STABILITY (YAW AXIS) ----------------- -------------------------------------------------------------------- ==================================================================== ----------------------------------------------------- Cnb — Yaw moment vs β (weathercock stability) | Float ----------------------------------------------------- • Desc: > The most important directional stability coefficient. > The "weathercock" effect makes the aircraft’s nose point into the relative wind during a sideslip (β), like a car realigning after a drift. • Real-World Examples & Analogy: > Large vs. small vertical tail: - Large tail (e.g., A-10): High Cnb, steady nose in crosswinds. - Small tail (e.g., F-100): Low Cnb, prone to fishtailing in slips. > Analogy: Weather vane swinging to face wind—vertical tail forces nose to track airflow. • Behavior: > In a sideslip (β ≠ 0), Cnb creates a yawing moment that pushes the nose back to align with the airflow, stabilizing direction. > A stronger Cnb reduces nose wobble. > Value Effects: - Higher: Stronger nose lock (less wobble). - Positive: Stabilizes direction (required). - Low / Zero: Fishtailing risk, unstable. • Limits / Tuning: > 0.1 – 0.2 → Stable (e.g., A-10, steady yaw). > 0.05 – 0.1 → Agile (e.g., MiG-15, balanced). > <0.05 – Unstable. • Components: > Primary: [VertTail]: This is the main job of the vertical tail. > Secondary: [Fuselage]:The fuselage, particularly the rear section, also contributes to Cnb (often in a destabilizing way that the tail must counteract). • Interactions: > This is the primary stability value provided by the [VertTail] component. > Its effectiveness can decrease at high Angles of Attack, which can be modeled with the CnbAlphaTable. • Situation Example: > During a rolling maneuver, the aircraft's nose wobbles from side to side. To increase directional stability and fix this, you would increase the Cnb on the [VertTail] component. • Note: > Sideslip (β): Nose misaligned with path. Cnb vs Cyb Notes: > Cnb focuses only on yaw (nose direction) via the vertical tail’s yaw moment, not the whole plane’s lateral movement. • Cnb straightens the nose > Cyb is about the sideways force from the fuselage and tail combined, affecting how the plane slides laterally. • Cyb pushes the whole plane sideways > Drifting car analogy • Cnb is like the steering wheel straightening the car • Cyb is the car’s body sliding sideways before it grips -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [VertTail] HasAeroCoefficients=TRUE LiftSurface=TRUE // Note: Set to TRUE even for vertical tails for some calculations // --- Base Value --- [VertTail] HasAeroCoefficients=TRUE Cnb=0.09 ; --- Cnb vs. Alpha Table --- CnbAlphaTableNumData=9 CnbAlphaTableStartX=0.0 CnbAlphaTableDeltaX=2.5 CnbAlphaTableData=1.0, 0.98, 0.95, 0.85, 0.7, 0.5, 0.35, 0.2, 0.1 // This translates to: // At 0 deg AoA, Cnb multiplier is 1.0 (Effective Cnb = 0.09) // At 2.5 deg AoA, Cnb multiplier is 0.98 (Effective Cnb = 0.0882) // At 5 deg AoA, Cnb multiplier is 0.95 (Effective Cnb = 0.0855) // At 7.5 deg AoA, Cnb multiplier is 0.85 (Effective Cnb = 0.0765) // At 10 deg AoA, Cnb multiplier is 0.7 (Effective Cnb = 0.063, weakening) // At 12.5 deg AoA, Cnb multiplier is 0.5 (Effective Cnb = 0.045, losing authority) // At 15 deg AoA, Cnb multiplier is 0.35 (Effective Cnb = 0.0315, very weak) // At 17.5 deg AoA, Cnb multiplier is 0.2 (Effective Cnb = 0.018, near useless) // At 20 deg AoA, Cnb multiplier is 0.1 (Effective Cnb = 0.009, spin likely) ──────────────────────────────────────────────────────────────────── -------------------------------------------- Cnr — Yaw-rate damping (moment vs r) | Float -------------------------------------------- • Desc: > The primary yaw damping force. > Creates a yaw moment that opposes the rate of yaw (r), like a shock absorber stopping nose wobble after a rudder kick. • Real-World Examples & Analogy: > Large vs. small vertical tail: - Large tail (e.g., A-10): High Cnr, steady tracking in crosswinds. - Small tail (e.g., F-100): Low Cnr, bouncy yaw in maneuvers. > Analogy: Arrow fletching damps wobble for straight path—larger fletching (tail) = stronger damping. • Behavior: > This is the "shock absorber" for the yaw axis. > It prevents the aircraft from overshooting its heading and oscillating side-to-side ("fishtailing") after a rudder input. > Value Effects: - More negative: Stronger damping, smooth yaw. - Less negative: Responsive but wobbly. - Zero: No damping, continuous yaw. • Limits / Tuning: > -0.3 to -0.5 → Stable (e.g., A-10, damped yaw). > -0.1 to -0.2 → Agile (e.g., MiG-15, quick yaw). > > -0.1 → Fishtailing. • Components: > Primary: [VertTail]: Like Cnb, this damping force is almost entirely generated by the vertical tail. > Secondary: [Fuselage]: rear adds slight damping • Interactions: > Complements Cnb (static yaw stability). > Scaled by CnrAlphaTable, often weaker at high AoA. • Situation Example: > After kicking the rudder to correct your aim and then neutralizing the pedals, the aircraft's nose swings past the target and oscillates a few times. To damp this out, you would make Cnr more negative. • Note: > Ties to Dutch roll; balance with Clr for yaw-roll stability. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [VertTail] HasAeroCoefficients=TRUE LiftSurface=TRUE // Note: Set to TRUE even for vertical tails for some calculations // --- Base Value --- Cnr=-0.3 ; --- Cnr vs. Alpha Table --- CnrAlphaTableNumData=9 CnrAlphaTableStartX=0.0 CnrAlphaTableDeltaX=2.0 CnrAlphaTableData=1.0, 0.98, 0.95, 0.85, 0.7, 0.5, 0.35, 0.2, 0.1 // This translates to: // At 0 deg AoA, Cnr multiplier is 1.0 (Effective Cnr = -0.3) // At 2 deg AoA, Cnr multiplier is 0.98 (Effective Cnr = -0.294) // At 4 deg AoA, Cnr multiplier is 0.95 (Effective Cnr = -0.285) // At 6 deg AoA, Cnr multiplier is 0.85 (Effective Cnr = -0.255) // At 8 deg AoA, Cnr multiplier is 0.7 (Effective Cnr = -0.21) // At 10 deg AoA, Cnr multiplier is 0.5 (Effective Cnr = -0.15, weakening) // At 12 deg AoA, Cnr multiplier is 0.35 (Effective Cnr = -0.105, very weak) // At 14 deg AoA, Cnr multiplier is 0.2 (Effective Cnr = -0.06, near useless) // At 16 deg AoA, Cnr multiplier is 0.1 (Effective Cnr = -0.03, spin likely) ──────────────────────────────────────────────────────────────────── ------------------------------------------------------------------------ Cnp — Yaw moment from roll-rate p (adverse yaw) | Cross-Coupling | Float ------------------------------------------------------------------------ • Desc: > The yawing moment created by the aircraft’s roll rate (p). > Primary cause of adverse yaw, where the nose swings opposite the roll due to drag differences. • Real-World Examples & Analogy: > Adverse yaw in eras: - Early jets (e.g., F-100 / MiG-15): Negative Cnp, nose yaws opposite roll. - Modern jets (e.g., F-104 with spoilers): Zero / positive Cnp, clean turns. > Analogy: Rowing a boat: When you take a strong stroke with the right oar to turn left, the oar also "drags" in the water, trying to pull the boat's stern to the right before the turn fully develops. Cnp models this drag-induced yaw. • Behavior: > As the aircraft rolls, the rising wing generates slightly more lift (and thus more induced drag) than the descending wing. > This drag difference creates a yawing moment in the opposite direction of the roll. > Value Effects: - Negative: Adverse yaw (early planes). - Zero: No yaw from roll (modern with spoilers). - Positive: Proverse yaw (nose follows roll). • Limits / Tuning: > -0.01 to -0.05 → Early Cold War (e.g., MiG-15, F-100, adverse yaw). > 0 to 0.01 → Later jets (e.g., F-104, F-16, minimal yaw). • Components: > Primary: [Wing]: Adverse yaw is caused by the differential drag of the rolling wings. > Secondary: [VertTail]: Can have a small effect. • Interactions: > Ties to Cldc (aileron power); countered with rudder or spoilers. • Situation Example: > You are modeling a Spitfire. When you roll left, the nose initially swings to the right before coming around. To simulate this, you would give the wing components a small negative Cnp value. • Note: > Key for realism in older planes; spoilers reduce it in modern jets. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- Cnp=-0.01 ; --- Cnp vs. Alpha Table --- CnpAlphaTableNumData=9 CnpAlphaTableStartX=0.0 CnpAlphaTableDeltaX=2.0 CnpAlphaTableData=1.0, 1.05, 1.1, 1.15, 1.1, 0.95, 0.8, 0.6, 0.4 // This translates to: // At 0 deg AoA, Cnp multiplier is 1.0 (Effective Cnp = -0.01) // At 2 deg AoA, Cnp multiplier is 1.05 (Effective Cnp = -0.0105) // At 4 deg AoA, Cnp multiplier is 1.1 (Effective Cnp = -0.011) // At 6 deg AoA, Cnp multiplier is 1.15 (Effective Cnp = -0.0115, peak) // At 8 deg AoA, Cnp multiplier is 1.1 (Effective Cnp = -0.011) // At 10 deg AoA, Cnp multiplier is 0.95 (Effective Cnp = -0.0095, weakening) // At 12 deg AoA, Cnp multiplier is 0.8 (Effective Cnp = -0.008) // At 14 deg AoA, Cnp multiplier is 0.6 (Effective Cnp = -0.006, near stall) // At 16 deg AoA, Cnp multiplier is 0.4 (Effective Cnp = -0.004, minimal) ==================================================================== -------------------------------------------------------------------- --------- SIDE FORCE COEFFICIENTS (FUSELAGE / TALL EFFECTS) -------- -------------------------------------------------------------------- ==================================================================== -------------------------------------------------------- Cyb — Sideforce vs β (sideslip) | Cross-Coupling | Float -------------------------------------------------------- • Desc: > The amount of pure sideways aerodynamic force generated during a sideslip (β). > Represents how the fuselage and vertical tail push the aircraft sideways, like a car drifting sideways in a turn. • Real-World Examples & Analogy: > Blocky vs. sleek fuselage: - Blocky/big tail (e.g., A-10): Strong Cyb, quick grip in slips. - Sleek/small tail (e.g., F-104): Weak Cyb, slippery slide. > Analogy: - Holding a large, flat board sideways in a strong wind. The wind pushes the board sideways. This is what Cyb represents for the aircraft's body and tail. • Behavior: > In sideslip, generates sideforce to move laterally, affecting slide feel. - Value Effects: • Negative: Pushes opposite slip (stabilizing grip). • Zero: No push, skatey slips. • Positive: Amplifies slip (unstable). • Limits / Tuning: > -0.05 to -0.1 → Stable (e.g., A-10, controlled slips). > -0.02 to -0.05 → Agile (e.g., MiG-15, easy sliding). > Near 0 → Skatey. • Components: > Primary: [VertTail], [Fuselage]: These are the two largest "side" surfaces of the aircraft and are the primary generators of sideforce in a slip. • Interactions: > Ties to Cnb for slip stability; weakens at high AoA; complements Clb in crosswinds. • Situation Example: > During a forward slip for landing, the aircraft is descending too quickly or not slipping sideways enough. > Adjusting Cyb on the fuselage and tail can fine-tune the amount of sideforce generated. • Note: > More neative Cyb = quicker "grip" from sliding. Cnb vs Cyb Notes: - Cnb focuses only on yaw (nose direction) via the vertical tail’s yaw moment, not the whole plane’s lateral movement. • Cnb straightens the nose - Cyb is about the sideways force from the fuselage and tail combined, affecting how the plane slides laterally. • Cyb pushes the whole plane sideways - Drifting car analogy • Cnb is like the steering wheel straightening the car • Cyb is the car’s body sliding sideways before it grips -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- ──────────────────────────────────────────────────────────────────── --------------------------------------------------------- Cyp — Sideforce from roll-rate p | Cross-Coupling | Float --------------------------------------------------------- • Desc: > The amount of sideways force (Y-axis) generated by the aircraft’s roll rate (p). > A subtle effect where rolling creates lateral motion, influenced by wing sweep or dihedral. • Real-World Examples & Analogy: > Swept vs. straight wings: - Swept (e.g., F-86 / F-100): Slight skid in rolls, Cyp -0.02 to 0.02. Dihedral / anhedral tweak sign / magnitude. - Straight (e.g., A-10): Minimal effect, Cyp near 0. > Analogy: - Imagine a kayak paddle during a wide, sweeping turn. As you roll your wrists and sweep the paddle through the water, the blade doesn't just turn the kayak; it also pushes the boat slightly sideways across the water's surface. • Behavior: > Rolling creates small net sideforce from wing motion. > Value Effects: - Positive: Push one way in roll (e.g., right in left roll). - Negative: Push opposite way. - Zero: No sideforce (common). • Limits / Tuning: > -0.01 to 0.01 → Minimal effect (e.g., A-10, stable rolls). > -0.02 to 0.02 → Skidding in rolls (e.g., F-100, Slippery). > 0.0 → No skid, default for most. • Components: > Primary: [Wing], [VertTail]: This subtle force is generated by the vertical movement of the wings and tail during a roll. • Interactions: > Ties to Cnp for roll-yaw-slip coupling; more in swept/anhedral wings. • Situation Example: > You’re modding an F-100. During a rapid left roll, it skids slightly right, mimicking its Slippery Sabre Dance. Set Cyp to 0.015 on [Wings] to capture this. > For an A-10, keep Cyp near 0.0 for stable, minimal slip in rolls. • Note: > Expert key; often 0.0 unless modeling specific skid. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- // --- Example 1: Conventional Straight-Wing (e.g., F-4B Phantom II) --- // For most conventional aircraft with straight wings, the Cyp effect is negligible and can be set to 0.0 or omitted entirely. [LeftWing] HasAeroCoefficients=TRUE ... Cyp=0.0 //------------------------------------------------------------------ // --- Example 2: Swept-Wing Fighter (e.g., F-100 Super Sabre) --- // This is an expert-level key used to model subtle cross-coupling effects. Here, a small positive Cyp is used to simulate the slight rightward skid that occurs during a rapid left roll, a known characteristic of early swept-wing jets. [LeftWing] HasAeroCoefficients=TRUE ... Cyp=0.015 ──────────────────────────────────────────────────────────────────── -------------------------------------------------------- Cyr — Sideforce from yaw-rate r | Cross-Coupling | Float -------------------------------------------------------- • Desc: > The amount of sideways force (Y-axis) generated by the aircraft’s yaw rate (r). > Adds lateral push from fuselage and tail during yaw, like a skid in a turn. • Real-World Examples & Analogy: > Large vs. small vertical tail: - Large tail (e.g., A-10): High Cyr, strong push in turns. - Small tail (e.g., F-100): Low Cyr, slippery turning. > Analogy: - Like a boat's rudder: When you turn it, it not only causes the stern to yaw but also physically pushes the stern sideways through the water. Cyr models this sideways push from the aircraft's tail during a yawing motion. • Behavior: > When yawing (e.g., right rudder), the fuselage and vertical tail push against the air, creating sideforce that moves the plane laterally (e.g., rightward slip). > Value Effects: - Positive: Push in yaw direction (common for turns). - Higher: Stronger skid, aids coordination. - Zero: Pivot-only, no skid. • Limits / Tuning: > 0.02–0.05 → Stable (e.g., A-10, lateral feel in turns). > 0.01–0.03 → Agile (e.g., MiG-15, minimal skidding). > 0.0 → No push, unrealistic. • Components: > Primary: [VertTail], [Fuselage]: This sideforce is generated by the fuselage and tail pushing against the air during a yawing motion. • Interactions: > Works with Cnr (damps yaw-rate) and Clr (roll from r) > β effects (Cnb / Clb) matter after r induces β; they shape the follow-on response. > Stronger with larger tails (more side area in yaw motion). • Situation Example: > Your aircraft model feels like it just "pivots" in place during a flat rudder turn, without much sideways movement. Increasing the Cyr value will create more sideforce during the yaw, making the turn feel more like a realistic skid. • Note: > Key for rudder "feel" in coordinated turns. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- // --- Example 1: Stable Aircraft (e.g., A-10) --- // For a stable aircraft with a large tail, a moderate positive Cyr // creates a realistic sideways push during rudder-induced yaws, // helping with the feel of a coordinated turn. [VertTail] HasAeroCoefficients=TRUE ... Cyr=0.04 //------------------------------------------------------------------ // --- Example 2: Agile Jet (e.g., MiG-15) --- // This is an expert-level key. For an agile but potentially "slippery" // jet, a lower Cyr value is used. This means rudder inputs will cause // more of a pure rotation (pivot) and less of a sideways slide, // which can be characteristic of some early jet designs. [VertTail] HasAeroCoefficients=TRUE ... Cyr=0.015 ==================================================================== -------------------------------------------------------------------- --- CONTROL SURFACE COEFFICIENTS (DELTAS) — from TControlSurface --- -------------------------------------------------------------------- ==================================================================== ------------------------------------- CDdc — Drag change per degree | Float ------------------------------------- • Desc: > Change in drag (CD) per degree of control surface deflection. • Real-World Examples & Analogy: > Spoilers vs. ailerons: - Spoilers (e.g., F-104 spoilerons): High CDdc, significant drag in rolls. - Ailerons (e.g., A-10): Low CDdc, minimal drag penalty. > Analogy: Opening hand wider out car window—slight deflection (some drag); full deflection (much more). • Behavior: > Adds parasitic drag proportional to deflection, slowing plane when surfaces move. - Value Effects: • Highe Positiver: More drag penalty (e.g., airbrakes). • Positive: Increases resistance (normal for surfaces). • Zero: No added drag, unrealistic. • Limits / Tuning: > 0.02–0.05 → Spoilers / airbrakes (e.g., F-100, high drag rolls). > 0.001–0.005 → Ailerons / elevators (e.g., MiG-15, low penalty). > 0.0 → No drag, unrealistic. • SystemType: > CONTROL_SURFACE • Interactions: > Adds to CD0 / CDL; scales with deflection; high for spoilerons (roll + drag). • Situation Example: > You want to model spoilers that also act as ailerons (spoilerons). You would give them a very high CDdc value so that when they deflect to create a roll, they also create significant drag. • Note: > Penalizes deflection with drag; parasitic = shape / size drag, not lift-related. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- // --- Example 1: Standard Control Surface (e.g., Aileron) --- // For a standard aileron or elevator, the drag increase from // deflection is a small but realistic penalty. [LeftAileron] SystemType=CONTROL_SURFACE MovingSurface=TRUE InputName=ROLL_CONTROL ... // Adds a small amount of drag whenever the aileron is deflected. CDdc=0.0003 //------------------------------------------------------------------ // --- Example 2: Spoileron or Airbrake --- // For a surface that is designed to act as a spoiler or airbrake, // the CDdc value is much higher to create a significant braking force. [LeftSpoileron] SystemType=CONTROL_SURFACE MovingSurface=TRUE InputName=ROLL_CONTROL SecondaryInputName=AIRBRAKE_CONTROL SecondaryInputFactor=1.0 ... // Adds a large amount of drag when deflected, creating a powerful // braking and roll-spoiling effect. CDdc=0.015 ──────────────────────────────────────────────────────────────────── ---------------------------------------- CLiftdc — Lift change per degree | Float ---------------------------------------- • Desc: > The change in lift coefficient (CL) per degree of surface deflection. • Real-World Examples & Analogy: > Flaps vs. elevators: - Flaps (e.g., A-10): High CLiftdc, boost lift for short landings. - Elevators (e.g., F-100): Moderate CLiftdc, quick pitch response. > Analogy: Bending paper airplane flap down—increases lift, looping up. • Behavior: > Boosts lift when deflected (e.g., down for positive CLiftdc). > Value Effects: - Positive: Adds lift (down deflection). - Zero: No lift change, useless. - Negative: Reduces lift (up deflection, ReverseInput). • Limits / Tuning: > 0.01–0.02 → Powerful flaps (e.g., A-10, low-speed lift). > 0.005–0.01 → Elevators (e.g., MiG-15, pitch control). > Negative → Up deflection (e.g., -0.01, downforce). • SystemType: > CONTROL_SURFACE, HIGHLIFT_DEVICE • Interactions: > Ties to CDdc (more lift = more drag); scales with CLiftdcAlphaTable. • Situation Example: > Your aircraft's flaps are not producing enough lift for a low-speed landing, requiring a very high nose attitude. You would increase the CLiftdc on the flap components to make them more effective. • Note: > Main for flap effectiveness; elevator pairs with Cmdc for pitch. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftElevator] SystemType=CONTROL_SURFACE MovingSurface=TRUE InputName=PITCH_CONTROL // --- Base Value --- CLiftdc=0.02 ; --- CLiftdc vs. Alpha Table --- CLiftdcAlphaTableNumData=9 CLiftdcAlphaTableStartX=0.0 CLiftdcAlphaTableDeltaX=2.0 CLiftdcAlphaTableData=1.0, 0.98, 0.95, 0.9, 0.8, 0.7, 0.5, 0.3, 0.1 // This translates to: // At 0 deg AoA, CLiftdc multiplier is 1.0 (Effective CLiftdc = 0.02) // At 2 deg AoA, CLiftdc multiplier is 0.98 (Effective CLiftdc = 0.0196) // At 4 deg AoA, CLiftdc multiplier is 0.95 (Effective CLiftdc = 0.019) // At 6 deg AoA, CLiftdc multiplier is 0.9 (Effective CLiftdc = 0.018) // At 8 deg AoA, CLiftdc multiplier is 0.8 (Effective CLiftdc = 0.016) // At 10 deg AoA, CLiftdc multiplier is 0.7 (Effective CLiftdc = 0.014, weakening) // At 12 deg AoA, CLiftdc multiplier is 0.5 (Effective CLiftdc = 0.01, mushy) // At 14 deg AoA, CLiftdc multiplier is 0.3 (Effective CLiftdc = 0.006, near stalled) // At 16 deg AoA, CLiftdc multiplier is 0.1 (Effective CLiftdc = 0.002, almost useless) ──────────────────────────────────────────────────────────────────── ------------------------------------------------ Cmdc — Pitching moment change per degree | Float ------------------------------------------------ • Desc: > The change in pitching moment coefficient (Cm) per degree of surface deflection. • Real-World Examples & Analogy: > Elevator vs. canard: - Elevator (e.g., F-86): Negative Cmdc, nose-up pitch. - Canard (e.g., Viggen): Positive Cmdc, nose-up from forward. > Analogy: Lever rotating nose—longer lever (higher Cmdc) needs less force. • Behavior: > Drives pitch rotation from deflection. > Value Effects (for rear aspect of aircraft, Canard is the opposite): - Negative: Nose-up for tail elevators (standard). - Zero: No pitch, useless. - Positive: Nose-up for canards. • Limits / Tuning: > -0.02 to -0.06 → Tail elevators (e.g., F-100, strong pitch). > 0.02 to 0.06 → Canards (e.g., Mirage III, high-AoA control). > 0.0 → No moment. • SystemType: > CONTROL_SURFACE • Interactions: > Ties to CLiftdc for lift-pitch balance; scales with CmdcAlphaTable. • Situation Example: > Plane sluggish in pitch: Make Cmdc -0.05 on [Elevator] or 0.05 on [Canard] for authority. • Note: > Sign depends on geometry / ReverseInput -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftElevator] SystemType=CONTROL_SURFACE MovingSurface=TRUE InputName=PITCH_CONTROL // --- Base Value --- Cmdc=-0.04 ; --- Cmdc vs. Alpha Table --- CmdcAlphaTableNumData=9 CmdcAlphaTableStartX=0.0 CmdcAlphaTableDeltaX=2.0 CmdcAlphaTableData=1.0, 0.98, 0.95, 0.9, 0.8, 0.6, 0.4, 0.25, 0.1 // This translates to: // At 0 deg AoA, Cmdc multiplier is 1.0 (Effective Cmdc = -0.04) // At 2 deg AoA, Cmdc multiplier is 0.98 (Effective Cmdc = -0.0392) // At 4 deg AoA, Cmdc multiplier is 0.95 (Effective Cmdc = -0.038) // At 6 deg AoA, Cmdc multiplier is 0.9 (Effective Cmdc = -0.036) // At 8 deg AoA, Cmdc multiplier is 0.8 (Effective Cmdc = -0.032) // At 10 deg AoA, Cmdc multiplier is 0.6 (Effective Cmdc = -0.024, weakening) // At 12 deg AoA, Cmdc multiplier is 0.4 (Effective Cmdc = -0.016, mushy) // At 14 deg AoA, Cmdc multiplier is 0.25 (Effective Cmdc = -0.01, near useless) // At 16 deg AoA, Cmdc multiplier is 0.1 (Effective Cmdc = -0.004, stalled) ──────────────────────────────────────────────────────────────────── ------------------------------------------ Cydc — Sideforce change per degree | Float ------------------------------------------ • Desc: > The change in sideforce coefficient (Cy) per degree of surface deflection. • Real-World Examples & Analogy: > Rudder in planes: - Large rudder (e.g., A-10): High Cydc, strong slips. - Small rudder (e.g., F-100): Low Cydc, slipery yaw. > Analogy: Boat rudder turning and pushing stern sideways—Cydc for lateral push. • Behavior: > Creates a pure sideways force when the rudder is deflected, pushing the entire aircraft laterally through the air. > It does not directly rotate the nose; it causes the aircraft to slip or skid. > Value Effects: - Positive: Creates sideforce in the direction of rudder input (standard). - Zero: No sideforce; results in an unrealistic pivot-only yaw. - Negative: Creates reversed sideforce, pushing the aircraft opposite to the rudder input (incorrect). • Limits / Tuning: > 0.005–0.01 → Powerful rudders (e.g., A-10, crosswind slips). > 0.001–0.005 → Agile jets (e.g., MiG-15, minimal skid). > 0.0 → No effect. • SystemType: > CONTROL_SURFACE • Interactions: > Ties to Cndc for rudder feel; scales with CydcAlphaTable. • Situation Example: > You want to create a powerful rudder for performing forward slips or acrobatic maneuvers like a stall turn. You would increase the absolute value of Cydc on the [Rudder] component. • Note: > Primary for rudder "feel" in sideslips; pairs with Cndc for yaw authority. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- // --- Example 1: Powerful Rudder (e.g., A-10) --- // For an aircraft with a large, powerful rudder designed for // precise low-speed handling and crosswind landings. [Rudder] SystemType=CONTROL_SURFACE MovingSurface=TRUE InputName=YAW_CONTROL ... // A high Cydc creates a strong sideways push for aggressive slips. Cydc=0.018 //------------------------------------------------------------------ // --- Example 2: Agile Jet (e.g., MiG-15) --- // For an early jet where the rudder's primary job is yawing, with // less emphasis on generating strong sideforce, resulting in a more // "slippery" feel in a sideslip. [Rudder] SystemType=CONTROL_SURFACE MovingSurface=TRUE InputName=YAW_CONTROL ... // A lower Cydc creates a weaker sideways push. Cydc=0.008 ──────────────────────────────────────────────────────────────────── ----------------------------------------------- Cldc — Rolling-moment change per degree | Float ----------------------------------------------- • Desc: > Change in rolling moment (Cl) per degree of aileron deflection. • Real-World Examples & Analogy: > Ailerons in planes: - Short wings (e.g., F-104): High Cldc, snappy rolls. - Long wings (e.g., A-10): Low Cldc, steady handling. > Analogy: Longer wrench for more turning power—higher Cldc needs less deflection for roll. • Behavior: > This is the "power" of your ailerons to create a rolling rotation. > The total rolling force is (Aileron Deflection × Cldc). > Value Effects: - Highe Positiver absolute: Faster roll. - Positive / Negative: Roll direction (opposite for paired ailerons, ReverseInput). - Zero: No roll, useless. • Limits / Tuning: > 0.04–0.06 → Snappy fighters (e.g., F-104, quick rolls). > 0.02–0.04 → Stable attackers (e.g., A-10, controlled rolls). > 0.0 → No effect. • SystemType: > CONTROL_SURFACE • Interactions: > Opposes Clp (damping); scales with CldcAlphaTable; ties to Cnp for adverse yaw. • Situation Example: > Your fighter jet's roll rate is too slow compared to its real-world counterpart. To make it more responsive, you would increase the absolute value of Cldc on the [Aileron] components. • Note: > Primary for roll rate; add Cndc to ailerons for adverse yaw in early jets. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftAileron] SystemType=CONTROL_SURFACE MovingSurface=TRUE InputName=ROLL_CONTROL // --- Base Value --- Cldc=0.01 ; --- Cldc vs. Alpha Table --- CldcAlphaTableNumData=9 CldcAlphaTableStartX=0.0 CldcAlphaTableDeltaX=2.0 CldcAlphaTableData=1.0, 0.98, 0.95, 0.9, 0.8, 0.7, 0.5, 0.3, 0.1 // This translates to: // At 0 deg AoA, Cldc multiplier is 1.0 (Effective Cldc = 0.01) // At 2 deg AoA, Cldc multiplier is 0.98 (Effective Cldc = 0.0098) // At 4 deg AoA, Cldc multiplier is 0.95 (Effective Cldc = 0.0095) // At 6 deg AoA, Cldc multiplier is 0.9 (Effective Cldc = 0.009) // At 8 deg AoA, Cldc multiplier is 0.8 (Effective Cldc = 0.008) // At 10 deg AoA, Cldc multiplier is 0.7 (Effective Cldc = 0.007, weakening) // At 12 deg AoA, Cldc multiplier is 0.5 (Effective Cldc = 0.005, mushy) // At 14 deg AoA, Cldc multiplier is 0.3 (Effective Cldc = 0.003, near useless) // At 16 deg AoA, Cldc multiplier is 0.1 (Effective Cldc = 0.001, stalled) ──────────────────────────────────────────────────────────────────── ---------------------------------------------- Cndc — Yawing moment change per degree | Float ---------------------------------------------- • Desc: > The change in yawing moment coefficient (Cn) per degree of surface deflection. • Real-World Examples & Analogy: > Rudder in planes: - Large rudder (e.g., A-10): High Cndc, strong yaw control. - Small rudder (e.g., F-100): Low Cndc, Slippery in crosswinds. > Analogy: Boat rudder steering power—larger rudder (higher Cndc) turns faster. • Behavior: > This is the "power" of your rudder to yaw the aircraft's nose left or right. > It can also be used on ailerons to simulate adverse yaw. > Value Effects: - Highe Positiver absolute: Stronger yaw. - Positive / Negative: Yaw direction (convention-dependent). - Zero: No yaw, weak. • Limits / Tuning: > 0.02–0.05 → Powerful rudders (e.g., A-10, crosswind control). > 0.01–0.02 → Agile jets (e.g., MiG-15, minimal yaw). > 0.0 → No effect. • SystemType: > CONTROL_SURFACE • Interactions: > Ties to Cydc for rudder feel; add to ailerons for adverse yaw. • Situation Example: > Your aircraft's rudder feels weak and cannot hold the nose straight during a crosswind landing. You would increase the absolute value of Cndc on the [Rudder] component to give it more authority. • Note: > Primary for rudder power; small opposite Cndc on ailerons for adverse yaw in older jets. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [Rudder] SystemType=CONTROL_SURFACE MovingSurface=TRUE InputName=YAW_CONTROL // --- Base Value --- Cndc=-0.02 ; --- Cndc vs. Alpha Table --- CndcAlphaTableNumData=9 CndcAlphaTableStartX=0.0 CndcAlphaTableDeltaX=2.0 CndcAlphaTableData=1.0, 0.98, 0.95, 0.9, 0.8, 0.7, 0.5, 0.3, 0.1 // This translates to: // At 0 deg AoA, Cndc multiplier is 1.0 (Effective Cndc = -0.02) // At 2 deg AoA, Cndc multiplier is 0.98 (Effective Cndc = -0.0196) // At 4 deg AoA, Cndc multiplier is 0.95 (Effective Cndc = -0.019) // At 6 deg AoA, Cndc multiplier is 0.9 (Effective Cndc = -0.018) // At 8 deg AoA, Cndc multiplier is 0.8 (Effective Cndc = -0.016) // At 10 deg AoA, Cndc multiplier is 0.7 (Effective Cndc = -0.014, weakening) // At 12 deg AoA, Cndc multiplier is 0.5 (Effective Cndc = -0.01, mushy) // At 14 deg AoA, Cndc multiplier is 0.3 (Effective Cndc = -0.006, near useless) // At 16 deg AoA, Cndc multiplier is 0.1 (Effective Cndc = -0.002, stalled) ==================================================================== -------------------------------------------------------------------- -------------------- GEOMETRY / REFERENCE POINTS ------------------- -------------------------------------------------------------------- ==================================================================== ------------------------------------------- Xac — Aerodynamic-center X-location | Float ------------------------------------------- • Desc: > The position of the component's Aerodynamic Center (AC) along the longitudinal axis (Y-axis in SF2). The AC is the point where all of the wing's lift is considered to act. • Real-World Examples & Analogy: > Stable Airliner: The AC is placed well behind the Center of Gravity (CG). - If the nose pitches up, the increased lift behind the CG creates a powerful nose-down moment that automatically corrects it. > Unstable Fighter (F-16): The AC is placed in front of the CG. - If the nose pitches up, the increased lift ahead of the CG creates a nose-UP moment, making the aircraft want to flip. - This instability is what makes it super-maneuverable, but it requires a flight computer (StabilityAugmentation=TRUE) to control. > Analogy: The balance point of a seesaw. The CGPosition is where you are sitting, and the Xac is the fulcrum (pivot point). - If you sit in front of the fulcrum, the seesaw is unstable and wants to flip. If you sit behind it, it's stable. • Behavior: > This is a critical factor in pitch stability. The distance between the Xac of the main wing and the aircraft's CGPosition (known as the static margin) is the primary determinant of the aircraft's stability. > High airspeed (transonic / Mach tuck) shifts AC backward, increasing nose-down tendency, regardless of CG—worsened by swept wings or blunt shapes. The curves of Mach tuck are also influenced by the various geometry shapes of the aircraft. - Model with XacMachTable for realism. - The XacMachTable is a critical interaction. It shifts this position (it is additive - This table is not a multiplier) at high Mach numbers • Limits / Tuning: > Stable: Set Xac behind the CGPosition. The further back, the more stable. > Neutral: Set Xac at the same point as the CGPosition. > Unstable: Set Xac in front of the CGPosition. > This is an expert-level key. It's often expressed as a fraction of the component's chord length (e.g., 0.25 for the quarter-chord point). • Component: > Primary: [Wing], [HorizontalTail] (All aerodynamic components have an Xac). • Interactions: > This is used to model "Mach tuck," a dangerous nose-down tendency in transonic flight. > Works in a direct relationship with CGPosition to define stability. • Situation Example: > You are modeling a stable trainer, but it has a dangerous tendency to pitch up uncontrollably. You would check that the Xac of the main wing is located sufficiently behind the aircraft's CGPosition. • Note: > This is one of the most powerful and sensitive keys for tuning pitch stability, alongside CGPosition. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficient // Note: This is a position shift, not a multiplier; positive adds aft for tuck. // --- Base Value --- Xac=0.25 ; --- Xac vs. Mach Table --- XacMachTableNumData=9 XacMachTableStartX=0.0 XacMachTableDeltaX=0.25 XacMachTableData=0.0, 0.0, 0.02, 0.05, 0.1, 0.15, 0.12, 0.1, 0.08 // This translates to: // At Mach 0.0, shift 0.0 (Effective Xac = 0.25) // At Mach 0.25, shift 0.0 (Effective Xac = 0.25) // At Mach 0.5, shift 0.02 (Effective Xac = 0.27) // At Mach 0.75, shift 0.05 (Effective Xac = 0.3, transonic start) // At Mach 1.0, shift 0.1 (Effective Xac = 0.35, tuck peak) // At Mach 1.25, shift 0.15 (Effective Xac = 0.4, max aft) // At Mach 1.5, shift 0.12 (Effective Xac = 0.37, recovery) // At Mach 1.75, shift 0.1 (Effective Xac = 0.35) // At Mach 2.0, shift 0.08 (Effective Xac = 0.33, supersonic stabilization) ──────────────────────────────────────────────────────────────────── -------------------------------------------- Qr — Downwash / relief factor (vs α) | Float -------------------------------------------- • Desc: > An advanced coefficient on a forward component (like a wing) that models the strength of its downwash. - General-purpose tool for modeling the aerodynamic interaction between a forward surface and a rear surface. - The sign of the value determines the direction of the effect • Real-World Examples & Analogy: > Conventional Aircraft (F-4): The main wing creates downwash that hits the tail, reducing the tail's effectiveness and increasing stability. > Canard Aircraft (Viggen): The forward canards create an "upwash" that hits the main wing, which can increase lift and maneuverability. > Analogy: A speedboat. The powerful V-shaped wake coming off the back of the boat is its "downwash." Any smaller boat crossing that wake will be pushed around and have its angle changed. The horizontal tail of an aircraft has to fly through the invisible "wake" of the main wing. • Behavior: > The downwash from a wing strikes the tail at a different angle, reducing the tail's effective Angle of Attack. This has a powerful stabilizing effect. > Downwash alters downstream AoA, stabilizing pitch; stronger at high α. > Value Effects: - Higher Positive: More tail reduction, stable but weak elevator. - Positive (Standard Wing): Stronger downwash (stabilizing). - Zero: No downwash, less stability. - Negative (Canard): Upwash that flows back to the main wing, increasing the main wing's effective Angle of Attack, energizing the airflow and allowing the wing to generate more lift at high AoA. • Limits / Tuning: > 0.2 – 0.3 → Strong Downwash > 0.1 – 0.2 → Weaker Downwash > 0.0 → No effect, unstable. > -0.1 - -0.2 → Weaker Upwash > -0.2 - -0.3 → Stronger Upwash • Component: > Primary: Forward, lift-generating surfaces like [Wing] or [Canard]. • Interactions: > Works directly with the DownwashAlphaTable, which modifies the strength of the downwash at different Angles of Attack. - Can also beused as 'UPwash" table by using negative values. - The final effect is a product of Qr and the table multiplier. • Situation Example: > Your aircraft model is too stable; it feels "stuck in mud" and won't pitch easily. This might be because the downwash effect is too strong, making the tail less effective. You would try reducing the Qr value on the main wing. • Note: > Qr is a powerful tool for modeling the complex aerodynamic interactions between different parts of the aircraft. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- Qr=0.25 ; --- Qr vs. Alpha Table --- QrAlphaTableNumData=9 QrAlphaTableStartX=0.0 QrAlphaTableDeltaX=2.0 QrAlphaTableData=0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.15, 1.2 // This translates to: // At 0 deg AoA, Qr multiplier is 0.5 (Effective Qr = 0.125) // At 2 deg AoA, Qr multiplier is 0.6 (Effective Qr = 0.15) // At 4 deg AoA, Qr multiplier is 0.7 (Effective Qr = 0.175) // At 6 deg AoA, Qr multiplier is 0.8 (Effective Qr = 0.2) // At 8 deg AoA, Qr multiplier is 0.9 (Effective Qr = 0.225) // At 10 deg AoA, Qr multiplier is 1.0 (Effective Qr = 0.25) // At 12 deg AoA, Qr multiplier is 1.1 (Effective Qr = 0.275) // At 14 deg AoA, Qr multiplier is 1.15 (Effective Qr = 0.2875, stronger near stall) // At 16 deg AoA, Qr multiplier is 1.2 (Effective Qr = 0.3, max strength) ──────────────────────────────────────────────────────────────────── -------------------------------------------------------------------- DownwashAlphaTable — Downwash effect vs α for downstream surfaces | Table -------------------------------------------------------------------- • Desc: > An advanced table that modifies the strength of downwash (or upwash) based on the Angle of Attack (α) of the component generating it (e.g., the main wing). • Real-World Examples & Analogy: > Conventional vs. T-tail vs. canard: - Conventional (e.g., F-4): Wing downwash reduces tail AoA, stabilizing pitch. - T-Tail (e.g., F-104): High AoA pops tail above wake, changing effectiveness. - Canard (e.g., Viggen): Upwash boosts wing lift, increasing maneuverability. > Analogy: Flag behind truck—low speed gentle flutter (low AoA), high speed turbulent whip (high AoA); table models wake change. • Behavior: > Multipliers applied to base Qr; strengthens/weakens downwash as AoA rises. - Value Effects: • Greater than 1.0: Strengthens Qr (e.g., stronger downwash). • Equal to 1.0: No change to Qr. • Less than 1.0: Weakens Qr. • Less than 0.0 (negative): Reverses to upwash (e.g., canards). • Limits / Tuning: > Multipliers 0.0–1.5 for downwash, -0.3 to -0.1 for upwash. - 0. 5 to 1.2 → Conventional (e.g., F-4, increasing with AoA). - 0.8 to 1.5 → T-tail (e.g., F-104, weaker at high AoA). - 0.0 → No effect, unstable. - -0.1 to -0.3 → Canard (e.g., Viggen, upwash boost). • Component / SystemType: > Primary: Forward, lift-generating surfaces like [Wing] or [Canard]. • Interactions: > This table is meaningless without a base Qr value to multiply. The final effect is always Final Effect = Qr Table_Multiplier. > It directly affects the stability provided by the [HorizontalTail] by changing the airflow that hits it. • Situation Example: > You are modeling an aircraft that becomes very unstable specifically at high Angles of Attack. You could use this table to weaken the stabilizing downwash effect from the main wing just before the stall, which would realistically decrease the tail's effectiveness and make the aircraft less stable. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Base Value --- // Set a base Qr for the downwash effect. Qr=0.2 // --- Downwash vs. Alpha Table --- // This table models how the downwash effect increases as the // wing's Angle of Attack (AoA) increases. DownwashAlphaTableNumData=4 DownwashAlphaTableStartX=0.0 DownwashAlphaTableDeltaX=5.0 DownwashAlphaTableData=0.2, 0.6, 0.9, 1.0 // This translates to: // At 0 deg AoA, Downwash Multiplier is 0.2 (Effective Qr = 0.04) // At 5 deg AoA, Downwash Multiplier is 0.6 (Effective Qr = 0.12) // At 10 deg AoA, Downwash Multiplier is 0.9 (Effective Qr = 0.18) // At 15 deg AoA, Downwash Multiplier is 1.0 (Effective Qr = 0.20, full strength) ==================================================================== -------------------------------------------------------------------- ---------- CONTROL EFFECTIVENESS TABLES — TControlSurface ---------- -------------------------------------------------------------------- ==================================================================== • Coefficient Notes: > These tables are unique to components with SystemType=CONTROL_SURFACE. > They act as a final global multiplier on the effectiveness of a control surface's deflection. > Their purpose is to model how control "feel" and authority change with airspeed and Mach number. > They multiply the final effect of all the ...dc coefficients for that surface. ──────────────────────────────────────────────────────────────────── -------------------------------------------------------------------- ControlIASTable — scales effectiveness vs Indicated Airspeed | Table -------------------------------------------------------------------- • Desc: > A table that scales the overall effectiveness of a control surface based on the Indicated Airspeed (IAS) in m/s. • Real-World Examples & Analogy: > High vs. low speed: - High IAS (e.g., F-104 dive): Low multiplier, prevents over-G. - Low IAS (e.g., A-10 landing): High multiplier, full authority. > Analogy: Car power steering—low speed (parking): high assist (easy turn); high speed (highway): low assist (stable). • Behavior: > Multiplier on control force; 1.0 = full, 0.5 = half effective. - Value Effects: • Greater than 1.0: Boosted authority (low speeds). • Equal to 1.0: Full effect. • Less than 1.0: Reduced sensitivity (high speeds). • Limits / Tuning: > Less than 100 m/s: 1.0 – 1.2 → Full authority (takeoff / landing). > Greater than 250 m/s: 0.6 – 0.8 → Reduced to prevent over-G. > Tune for feel across speed range. • Component / SystemType: > Primary: [ControlSurface] - (Ailerons - Elevators - Rudders • Interactions: > This table works in conjunction with the ControlMachTable. > The game engine likely multiplies the effects of both tables together to get the final effectiveness scalar. > It also interacts with MaxControlSpeed, which reduces the rate of surface movement at high speed. • Situation Example: > Your new jet fighter model feels perfectly responsive at low speeds, but at high speeds, it's extremely twitchy and easy to over-G. You would create a ControlIASTable that gradually reduces the control effectiveness as the IAS increases, making the aircraft feel more stable and realistic at high speed. • Note: > This table is based on Indicated Airspeed (IAS), which is directly related to dynamic pressure. It is the primary tool for modeling speed-based changes in control feel. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftAileron] SystemType=CONTROL_SURFACE MovingSurface=TRUE InputName=ROLL_CONTROL Cldc=0.01 // Base for reference ; --- ControlIAS Table (scales effectiveness vs IAS in m/s) --- ControlIASTableNumData=5 ControlIASTableStartX=0.0 ControlIASTableDeltaX=100.0 ControlIASTableData=1.0, 1.0, 0.9, 0.8, 0.7 // This translates to: // At 0 m/s IAS, multiplier is 1.0 (Full effectiveness) // At 100 m/s IAS, multiplier is 1.0 (Full at low speed) // At 200 m/s IAS, multiplier is 0.9 (Slight reduction) // At 300 m/s IAS, multiplier is 0.8 (Heavier feel) // At 400 m/s IAS, multiplier is 0.7 (Reduced at high speed to prevent over-G) ──────────────────────────────────────────────────────────────────── -------------------------------------------------------------------- ControlMachTable — scales effectiveness vs Mach number | Table -------------------------------------------------------------------- • Desc: > A table that scales the overall effectiveness of a control surface based on the Mach number. • Real-World Examples & Analogy: > Transonic vs. supersonic: - Transonic (e.g., F-86 dive): Low multiplier, mushy controls from shockwaves. - Supersonic (e.g., F-104): Partial recovery, stable controls. > Analogy: Steering canoe over waterfall—smooth water (subsonic): effective; chaotic waterfall (transonic): useless; calmer bottom (supersonic): recovers. • Behavior: > Multiplier on force for compressibility; dip at M0.9–1.2 for tuck/blanketing. > Value Effects: - Greater than 1.0: Boosted (supersonic recovery). - Equal to 1.0: Full effect. - Less than 1.0: Reduced (transonic loss). • Limits / Tuning: > This table is essential for any aircraft that can approach or exceed the speed of sound. - Mach 0 9 – 1.2: 0.5 – 0.8 → Transonic dip (mushy controls). - Above Mach 1.2: 0.8 – 1.2 → Supersonic recovery. - Tune for high-speed feel. • Component / SystemType: > Transonic / Supersonic Aircraft - Primary: [ControlSurface] • Ailerons • Elevators • Rudders • Interactions: > Works in conjunction with the ControlIASTable. > The final effectiveness is a combination of both the IAS and Mach effects. • Situation Example: > You are modeling an early jet fighter like the F-86. As you dive through the sound barrier, the controls should feel "mushy" and unresponsive. You would create a ControlMachTable with a sharp dip in the effectiveness multiplier around Mach 0.95 to simulate this dangerous transonic characteristic. • Note: > This table is specifically for modeling compressibility effects. For general speed-related "heaviness," use ControlIASTable. The two tables work together to create a realistic high-speed control feel. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftElevator] SystemType=CONTROL_SURFACE MovingSurface=TRUE InputName=PITCH_CONTROL Cmdc=-0.04 // Base for reference ; --- ControlMach Table (scales effectiveness vs Mach) --- ControlMachTableNumData=9 ControlMachTableStartX=0.0 ControlMachTableDeltaX=0.25 ControlMachTableData=1.0, 1.0, 0.95, 0.85, 0.7, 0.6, 0.7 ==================================================================== -------------------------------------------------------------------- --------------------- STALL / ENVELOPE BEHAVIOR -------------------- -------------------------------------------------------------------- ==================================================================== • Coefficient Notes: > These keys, found in a [Component] section, define what happens when a lifting surface exceeds its critical Angle of Attack (AoA). They are the tools for modeling everything from a gentle, mushy stall to a violent, unrecoverable spin. ──────────────────────────────────────────────────────────────────── ------------------------------------------------------------- CheckStall — Enable stall modeling for this surface | Boolean ------------------------------------------------------------- • Desc: > The master on/off switch for all stall-related physics on this component. • Real-World Examples & Analogy: > Wing vs. fuselage: - Wing (e.g., F-100): CheckStall=TRUE, stalls essential. - Fuselage (e.g., A-10): CheckStall=FALSE, no significant stall. • Except, if the fuseluge is blended with the wing (e.g. B-2 Spirit) or have a wide, flat fuselage that can generate lift (e.g. F-14 Tomcat), then CheckStall=TRUE. > Analogy: This is the circuit breaker for the stall warning system. If it's off, none of the other stall keys will have any effect. • Behavior: > TRUE: Monitors AoA, applies stall physics (AlphaStall, CLmax, StallMoment). > FALSE: No stall, lift continues indefinitely. • Limits / Tuning: > TRUE: Essential for all primary lifting surfaces ([Wing], [HorizontalTail], [VertTail]) - Also aplies to (Fuselage) if blended with wing or have very wide, flat fuselage > FALSE: Use for non-lifting or minor components to simplify the model and save processing power. • Component: > Primary: [Wing], [HorizontalTail], [VertTail]. > Secondary: [Fuselage], if blended with wing or have very wide, flat fuselage • Interactions: > This key is the "gate" for all other stall keys. > If CheckStall=FALSE, none of the other Stall... or Alpha... keys for this component will be read. • Situation Example: > You are creating a flight model and the aircraft refuses to stall, no matter how hard you pull back on the stick. The first thing you should check is that CheckStall=TRUE is set on your main wing components. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Stall Characteristics --- // This is the master switch. If set to TRUE, the game will read // all other stall-related keys for this component. If FALSE, the // wing will not stall, regardless of other settings. CheckStall=TRUE ──────────────────────────────────────────────────────────────────── ------------------------------------------------------- AlphaStall — AoA (deg) where stall onset begins | Float ------------------------------------------------------- • Desc: > The critical Angle of Attack (in degrees) where the airflow begins to separate from the wing's surface and the stall begins. • Real-World Examples & Analogy: > Straight vs. swept wing: - Straight (e.g., A-10): High AlphaStall (16–18°), forgiving. - Swept (e.g., F-100): Low AlphaStall (12–14°), early stall. > Analogy:The "redline" on your car's tachometer. It's the limit you're not supposed to exceed. As you approach it, the engine starts to strain, just as a wing starts to buffet as it approaches AlphaStall. • Behavior: > When the component's AoA exceeds this value, the game begins to smoothly blend from the normal aerodynamic model to the post-stall model, using the Stall keys and tables. > Value Effects: - Higher: Later stall, better low-speed (straight wings). - Lower: Earlier stall, high-speed design (swept wings). • Limits / Tuning: > Rough data based on wing types — common for known planes, but not identical for all; always check real aircraft data for precision. - 16 – 18° → Trainers (e.g., Cessna, forgiving). - 14 – 16° → WWII fighters (e.g., Spitfire, balanced). - 12 – 15° → Swept jets (e.g., F-100, early stall). - 20 – 30° → Delta wings (e.g., Mirage III, high-AoA). - 15 - 20° → Flying wing (YB-49, unstable without Fly-By-Wire) - 20 - 25° → Flying wing (B-2 with Fly-By-Wire) • Component: > Primary: [Wing], [HorizontalTail], [VertTail]. > Secondary: [Fuselage], if blended with wing or have very wide, flat fuselage • Interactions: > This is the trigger for CLmax, StallMoment, StallDrag, and all the Stall Table keys. • Situation Example: > You want to model a wing that stalls at the wingtips first (a dangerous condition). You would create an [OuterWing] component and give it a lower AlphaStall than the [InnerWing] component. • Note: > This is one of the most important keys for defining an aircraft's handling at the edge of the envelope. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Stall Characteristics --- // This is the trigger point. When the wing's Angle of Attack // exceeds this value (in degrees), the stall process begins. CheckStall=TRUE AlphaStall=16.0 ──────────────────────────────────────────────────────────────────── -------------------------------------------------------------- CLmax — Max lift coefficient before stall limits apply | Float -------------------------------------------------------------- • Desc: > The maximum Coefficient of Lift the wing can produce, which occurs at the AlphaStall point. • Real-World Examples & Analogy: > High-lift vs. low-lift wings: - High-lift = Straight, thicker wings (e.g., A-10) • CLmax ~1.8+, excellent low-speed glide and short landings. - Low-lift = Non-straight wings (e.g., sweep or delta), thinner profiles (e.g., F-104) •CLmax ~1.2, speed-focused with early stall. > Analogy: Engine's max horsepower—CLa gets you there fast, CLmax is the peak power available. • Behavior: > Exceeds AlphaStall: Lift drops from CLmax per StallLiftTable. - Value Effects: • Higher: More peak lift, lower stall speed. • Lower: Less lift, higher speed needed. • Limits / Tuning: > 1.3 – 1.6 → General (e.g., F-86, balanced). > 1.8 – 2.2 → High-lift flaps/slats (e.g., A-10, short landing). > 1.1 – 1.3 → High-speed (e.g., F-104, thin wings). • Component: > Primary: [Wing], [HorizontalTail], [VertTail]. > Secondary: [Fuselage], if blended with wing or have very wide, flat fuselage • Interactions: > A higher CLmax for a given CLa means the wing will stall at a higher Angle of Attack. The combination of CLa and CLmax defines the shape of the pre-stall lift curve. • Situation Example: > Your aircraft has a very high takeoff and landing speed. To lower it, you need to increase the maximum lift the wings can generate by increasing their CLmax value. • Note: > CLmax is a primary factor in determining an aircraft's minimum flying speed and its maximum instantaneous turn rate. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Stall Characteristics --- // This is the trigger point. When the wing's Angle of Attack // exceeds this value (in degrees), the stall process begins. CheckStall=TRUE AlphaStall=16.0 // The following keys are activated by AlphaStall CLmax=1.45 ──────────────────────────────────────────────────────────────────── ---------------------------------------------------- StallMoment — Extra pitching moment in stall | Float ---------------------------------------------------- • Desc: > An additional pitching moment that is applied only when the component is stalled. > This is the most critical key for post-stall behavior. • Real-World Examples & Analogy: > Stable vs. unstable stall: - Stable trainer (e.g., Cessna): Negative StallMoment, nose drops for recovery. - Unstable T-tail jet (e.g., Boeing 727): Positive StallMoment, nose-up deep stall. > Analogy: A self-correcting toy. A stable aircraft with a negative StallMoment is like a Weeble Wobble—when you push it over, it wants to pop back upright on its own. • Behavior: > Blends in during stall; affects recovery. - Value Effects: • Positive: Nose-up, unstable/deep stall risk. • Zero: Neutral, no natural recovery. • Negative: Nose-down, recoverable stall. • Limits / Tuning: > -0.005 to -0.02 → Stable (e.g., Cessna, safe recovery). > Near 0 → Neutral/aggressive (e.g., fighters). > Positive → Unstable (e.g., T-tail jets, spin risk). • Component: > Primary: [Wing] > Secondary: [Fuselage]: Only if it's also configured to produce body lift (CLa greater than 0). • Interactions: > Its effect is modified by the StallXacShiftTable, which also affects the pitching moment during a stall. • Situation Example: > You are modeling an aggressive fighter that should have a challenging stall. You would set StallMoment to a value very close to zero, requiring the pilot to take active steps to recover instead of the plane recovering on its own. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Stall Characteristics --- // This is the trigger point. When the wing's Angle of Attack // exceeds this value (in degrees), the stall process begins. CheckStall=TRUE AlphaStall=16.0 // The following keys are activated by AlphaStall CLmax=1.45 StallMoment=-0.005 ... ──────────────────────────────────────────────────────────────────── -------------------------------------------------- StallDrag — Extra drag multiplier in stall | Float -------------------------------------------------- • Desc: > A multiplier for the extra drag that is applied when the component is stalled. • Real-World Examples & Analogy: > High vs. low stall drag: - High (e.g., straight wing trainer): Strong StallDrag, rapid slowdown. - Low (e.g., delta wing fighter): Less StallDrag, sustained high-AoA. > Analogy: Parachute deploying in stall—speed drops rapidly (high StallDrag). • Behavior: > Increases drag in stall, causing rapid airspeed loss. - Value Effects: • Higher Positive: Pronounced deceleration. • Positive: More drag, buffeting stall. • Zero: No extra drag, mild stall. • Limits / Tuning: > 0.03–0.05 → Pronounced stall (e.g., Cessna, buffeting). > 0.01–0.02 → Mild stall (e.g., delta wings, sustained AoA). > 0.0 → No extra drag. • Component: > Primary: [Wing] > Secondary: [Fuselage], if blended with wing or have very wide, flat fuselage • Interactions: > Works in conjunction with the StallDragTable, which can define a more precise curve for the post-stall drag increase. • Situation Example: > Your aircraft's stall is too gentle; it just "mushes" downwards without a significant loss of speed. By increasing StallDrag, you will create the characteristic buffeting and rapid deceleration of a real stall. • Note: > Creates characteristic stall buffeting; key for recovery feel. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE CheckStall=TRUE AlphaStall=16.0 CLmax=1.4 StallDrag=0.01 ; --- StallDragTable vs. Alpha --- StallDragTableNumData=9 StallDragTableStartX=16.0 StallDragTableDeltaX=2.0 StallDragTableData=1.2, 1.4, 1.6, 1.8, 2.2, 2.6, 3.0, 3.5, 4.0 // This translates to: // At 16 deg AoA, Drag multiplier is 1.2 (Effective StallDrag = 0.012) // At 18 deg AoA, Drag multiplier is 1.4 (Effective StallDrag = 0.014) // At 20 deg AoA, Drag multiplier is 1.6 (Effective StallDrag = 0.016) // At 22 deg AoA, Drag multiplier is 1.8 (Effective StallDrag = 0.018) // At 24 deg AoA, Drag multiplier is 2.2 (Effective StallDrag = 0.022) // At 26 deg AoA, Drag multiplier is 2.6 (Effective StallDrag = 0.026) // At 28 deg AoA, Drag multiplier is 3.0 (Effective StallDrag = 0.03) // At 30 deg AoA, Drag multiplier is 3.5 (Effective StallDrag = 0.035) // At 32 deg AoA, Drag multiplier is 4.0 (Effective StallDrag = 0.04, massive drag deep in stall) ──────────────────────────────────────────────────────────────────── ---------------------------------------------------------------- AlphaDepart — AoA (deg) where departure / spin may begin | Float ---------------------------------------------------------------- • Desc: > The Angle of Attack (in degrees) at which the aircraft is likely to depart from controlled flight and enter a more violent, unpredictable state like a spin. • Real-World Examples & Analogy: > Docile vs. spin-prone: - Docile trainer (e.g., Cessna): High AlphaDepart (20°+), forgiving mush. - Mush = Soft stall where the plane loses lift and sinks gradually without a sharp nose drop, like mushing through mud. - Spin-prone fighter (e.g., F-104): Low AlphaDepart, abrupt spin. > Analogy: Frozen lake ice cracking (AlphaStall warning) to shattering (AlphaDepart no return). • Behavior: > This key defines the upper boundary of the controllable "mush zone" that begins at AlphaStall. > When the wing's AoA exceeds AlphaDepart's value, the game's physics engine can introduce more dramatic and less predictable aerodynamic effects, representing a full departure from stable flight. - AlphaDepart value from AlphaStall: • Higher: Larger forgiving zone (stable planes). • Lower: Abrupt departure (aggressive planes). • Same as AlphaStall: Immediate spin. • Limits / Tuning: > This value must be greater than AlphaStall. > Greater than AlphaStall (15 – 30°). - 20 – 25° → Stable (e.g., A-10, forgiving spin). - 15 – 20° → Aggressive (e.g., F-100, quick departure). - Close to AlphaStall → Spin-prone, expert. • Component: > Primary: [Wing] > Secondary: [Fuselage], if blended with wing or have very wide, flat fuselage • Interactions: > The tendency to actually depart at this AoA is strongly influenced by StallMoment. A positive (nose-up) StallMoment will actively push the aircraft's nose up towards the AlphaDepart angle, making a spin much more likely. • Situation Example: > You are modeling an aircraft that is known to be very dangerous in a stall and prone to spinning. You would set AlphaDepart to a value relatively close to AlphaStall (e.g., AlphaStall=15, AlphaDepart=19) and give it a neutral or slightly positive StallMoment. • Note: > This is an expert-level key for defining the character and danger of a deep stall. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Stall Characteristics --- CheckStall=TRUE AlphaStall=16.0 CLmax=1.45 // --- Departure from Controlled Flight --- // This is the Angle of Attack (in degrees) at which the aircraft // is likely to fully depart from controlled flight and enter a spin. // It should be set a few degrees higher than AlphaStall to create a // controllable "mush zone" before the hard stall. AlphaDepart=22.0 // A positive StallMoment can be used to make the departure more aggressive. StallMoment=0.002 ... ──────────────────────────────────────────────────────────────────── -------------------------------------- AlphaMax — Max AoA clamp (deg) | Float -------------------------------------- • Desc: > The absolute maximum Angle of Attack (in degrees) that the component can physically reach. • Real-World Examples & Analogy: > Normal vs. extreme: - Normal (e.g., F-86): AlphaMax 90°, flat spin limit. - Thrust vectoring (e.g., F-22): AlphaMax 90°+, extreme maneuvers. > Analogy: Ground stopping a fall—AlphaMax is hard limit for motion. • Behavior: > This key acts as a hard clamp in the physics engine. > The game will not allow the component's Angle of Attack to exceed this value under any circumstances. • Lower: Restricts envelope (prevents tumbling). • Limits / Tuning: > Must be greater than AlphaDepart (30 – 90°+). - 45 – 60° → Fighters (e.g., F-16, high-AoA). - 90° → Conventional (e.g., F-100, flat spin). - Greater than 90° → Vectoring jets (e.g., F-22). • Component / SystemType: > Primary: [Wing] > Secondary: [Fuselage], if blended with wing or have very wide, flat fuselage • Interactions: > This is the final backstop for all other stall-related keys. It is the absolute boundary of the flight envelope. • Situation Example: > Your aircraft model is behaving erratically in a spin, sometimes tumbling in an unrealistic way where the AoA exceeds 90 degrees. You would set AlphaMax=90.0 to clamp the physics and prevent this unrealistic behavior. • Note: > This is a safety and stability key, used to define the absolute boundaries of the post-stall physics simulation. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Stall Characteristics --- // These keys define the stall progression. CheckStall=TRUE AlphaStall=16.0 CLmax=1.45 AlphaDepart=22.0 // --- Absolute AoA Limit --- // This is the hard clamp. The game's physics engine will not allow // the component's Angle of Attack to exceed this value, preventing // unrealistic tumbling or post-stall behavior. A value of 90.0 is // a realistic limit for a flat spin. AlphaMax=90.0 ... ──────────────────────────────────────────────────────────────────── ---------------------------------------------------------------------- StallHysteresis — AoA gap between stall entry / exit | Float (Degrees) ---------------------------------------------------------------------- • Desc: > This makes the stall "sticky." It's the number of degrees of AoA you must reduce below the AlphaStall point to recover from the stall. • Real-World Examples & Analogy: > Forgiving vs. sticky stall: - Low hysteresis (e.g., Cessna): Quick recovery, small gap (1 – 2°). - High hysteresis (e.g., delta wing fighter): Sticky, larger gap (3 – 5°). > Analogy: Unsticking tape—takes extra effort (lower AoA) to separate after sticking. • Behavior: > If AlphaStall=16 and StallHysteresis=2.0, the wing will not un-stall and re-attach its airflow until the AoA drops all the way back down to 14 degrees. • Limits / Tuning: > 1.0 – 2.0° → Forgiving (e.g., trainers, quick recovery). > 2.0 – 3.0° → Sticky (e.g., swept wings, deliberate recovery). > 0.0 → Instant recovery. • Component: > Primary: [Wing] > Secondary: [Fuselage], if blended with wing or have very wide, flat fuselage • Interactions: > Ties to AlphaStall for stall/recovery AoA. • Situation Example: > Your aircraft recovers from a stall too easily, the instant the nose drops slightly. By adding StallHysteresis=2.0, you force the pilot to make a more deliberate recovery action (pushing the nose further down) to fully un-stall the wings. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE // --- Stall Characteristics --- CheckStall=TRUE AlphaStall=16.0 CLmax=1.45 // --- Stall Hysteresis --- // This key makes the stall "sticky." It defines the number of degrees // of AoA that you must reduce below the stall angle to recover. // In this example, the wing stalls at 16 degrees, but won't recover // until the AoA drops below 14 degrees (16 - 2). StallHysteresis=2.0 ... ──────────────────────────────────────────────────────────────────── ------------------------------------------------------------ StallLiftTable — Detailed CL shaping deep into stall | Table ------------------------------------------------------------ • Desc: > An advanced table that defines a precise curve for the Coefficient of Lift (CL) in the post-stall regime, after `AlphaStall` has been exceeded. • Real-World Examples & Analogy: > Docile vs. sharp stall: - Docile (e.g., Cessna): Gradual CL drop, mushy stall. - Sharp (e.g., F-4): Steep CL loss, violent wing drop. > Analogy: Cliff fall shape—gentle slope (soft stall) vs. vertical drop (sharp stall). • Behavior: > Multipliers applied to base CLmax; customizes lift fade post-stall. - Value Effects: • 1.0: Full CLmax lift. • Less than 1.0: Partial lift loss (stalled). • 0.0: No lift. • Limits / Tuning: > Multipliers start at 1.0 at AlphaStall, decrease thereafter. - 1.0 to 0.7 → Soft stall (e.g., trainers). - 1.0 to 0.3 → Sharp stall (e.g., swept jets). • Component: > **Primary:** `[Wing]` and any other lift-generating component with `CheckStall=TRUE`. • Interactions: > This table's X-axis (`StartX`) should begin at the `AlphaStall` value to ensure a smooth transition. > It works in conjunction with `StallMoment` and `StallDragTable` to define the complete post-stall experience. • Situation Example: > You are modeling a high-performance jet that is known for a very sharp and dangerous stall. After setting `AlphaStall`, you would create a `StallLiftTable` where the multiplier drops very rapidly (e.g., from `1.0` to `0.4`) in just a few degrees of AoA to simulate this violent loss of lift. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE CheckStall=TRUE AlphaStall=16.0 CLmax=1.4 // --- StallLiftTable --- // This example creates a moderately sharp stall. The lift tapers off // gradually at first, then drops more steeply as the stall deepens. StallLiftTableNumData=9 StallLiftTableStartX=16.0 StallLiftTableDeltaX=2.0 StallLiftTableData=1.0, 0.9, 0.7, 0.5, 0.4, 0.3, 0.2, 0.15, 0.1 // This translates to: // At 16 deg AoA, CL multiplier is 1.0 (Effective CL = 1.4) // At 18 deg AoA, CL multiplier is 0.9 (Effective CL = 1.26) // At 20 deg AoA, CL multiplier is 0.7 (Effective CL = 0.98) // At 22 deg AoA, CL multiplier is 0.5 (Effective CL = 0.7) // At 24 deg AoA, CL multiplier is 0.4 (Effective CL = 0.56, sharp drop) // At 26 deg AoA, CL multiplier is 0.3 (Effective CL = 0.42) // At 28 deg AoA, CL multiplier is 0.2 (Effective CL = 0.28) // At 30 deg AoA, CL multiplier is 0.15 (Effective CL = 0.21) // At 32 deg AoA, CL multiplier is 0.1 (Effective CL = 0.14, minimal lift) ──────────────────────────────────────────────────────────────────── ---------------------------------------------------- StallXacShiftTable — Xac shift vs α in stall | Table ---------------------------------------------------- • Desc: > An expert-level table that models the physical **shift** of the wing's Aerodynamic Center (`Xac`) as it enters a deep stall. This is a powerful tool for tuning post-stall pitching behavior. • Real-World Examples & Analogy: > Stable vs. unstable stall: - Forward shift (e.g., Cessna): Nose-down recovery. - Rearward shift (e.g., swept wings like F-100): Nose-up deep stall. > Analogy: Seesaw fulcrum sliding—forward (positive shift) tips nose down (safe); backward (negative) tips up (dangerous). • Behavior: > Additive shifts (meters) to base Xac in stall. > Value Effects: - Positive: Forward shift, nose-down (safe recovery). - Zero: No shift, neutral. - Negative: Rearward shift, nose-up (unstable spin). • Limits / Tuning: > 0.05 to 0.15 → Forward (stable, e.g., A-10, self-recovery). > Near 0 → Neutral (aggressive, e.g., F-16). > -0.05 to -0.15 → Rearward (unstable, e.g., F-100, pitch-up stall). • Component / SystemType: > **Primary:** `[Wing]` and any other lift-generating component with `CheckStall=TRUE`. • Interactions: > This table works directly with **`StallMoment`** to create the final post-stall pitching behavior. The moments from both are added together. > It is only active after `AlphaStall` is exceeded. • Situation Example: > You are modeling an aircraft known for a dangerous "pitch-up" moment upon stalling. In addition to a neutral or positive `StallMoment`, you would use a `StallXacShiftTable` with negative values to simulate the center of lift moving rearward, creating a powerful and realistic nose-up tendency. -------------------------------------------------------------------- • INI USAGE EXAMPLE ------------------- [LeftWing] HasAeroCoefficients=TRUE LiftSurface=TRUE CheckStall=TRUE AlphaStall=16.0 CLmax=1.4 // --- Base Aerodynamic Center --- Xac=0.25 // --- StallXacShiftTable --- // This example models a rearward shift of the AC during the stall, // which will create a nose-up pitching moment. StallXacShiftTableNumData=9 StallXacShiftTableStartX=16.0 StallXacShiftTableDeltaX=2.0 StallXacShiftTableData=0.0, -0.02, -0.04, -0.06, -0.08, -0.1, -0.1, -0.08, -0.06 // This translates to: // At 16 deg AoA, Xac shift is 0.0 m (Effective Xac = 0.25 m) // At 18 deg AoA, Xac shift is -0.02 m (Effective Xac = 0.23 m) // At 20 deg AoA, Xac shift is -0.04 m (Effective Xac = 0.21 m) // At 22 deg AoA, Xac shift is -0.06 m (Effective Xac = 0.19 m) // At 24 deg AoA, Xac shift is -0.08 m (Effective Xac = 0.17 m) // At 26 deg AoA, Xac shift is -0.1 m (Effective Xac = 0.15 m, peak rearward) // At 28 deg AoA, Xac shift is -0.1 m (Effective Xac = 0.15 m, holds) // At 30 deg AoA, Xac shift is -0.08 m (Effective Xac = 0.17 m) // At 32 deg AoA, Xac shift is -0.06 m (Effective Xac = 0.19 m, slight recovery) ==================================================================== ──────────────────────────────────────────────────────────────────── ─────────────────────────── TABLE SYSTEM ─────────────────────────── ──────────────────────────────────────────────────────────────────── ==================================================================== GENERAL FORMAT (applies to …MachTable / …AlphaTable / ControlIASTable / ControlMachTable) 1) NumData - Count of points (N). 2) StartX - Starting X value (Mach for MachTables, degrees for AlphaTables, m/s for IASTables). 3) DeltaX - Uniform step between X points (Greater than 0). 4) Data - N comma-separated multipliers for the target quantity (the coefficient or effect this table belongs to). • Example targets: - CD0MachTable → multiplies CD0 - CLaMachTable → multiplies CLa - CmqMachTable → multiplies Cmq - CldcAlphaTable → multiplies Cldc - ControlIASTable → multiplies control effectiveness. • Exception: XacMachTable provides position offsets/shifts, not multipliers. ---------------------------------- SF2 ENGINE RULES (SF2 behavior) • Linear interpolation between points. • Clamping outside range: values below first X use first Y; above last X use last Y (no extrapolation). • Alpha (AoA) is in degrees. Mach is dimensionless. IAS is in m/s. • If a table is missing, engine uses 1.0 (no change) for that factor. • Key name must match exactly (case/spelling). Place the table in the component that owns the base value. ──────────────────────────────────────────────────────────────────── ----------------------- MACH TABLE (…MachTable) ----------------------- Purpose: model compressibility/transonic effects by scaling a base quantity with Mach. INI EXAMPLE (CD0 vs Mach) CD0=0.015 CD0MachTableNumData=5 CD0MachTableStartX=0.6 CD0MachTableDeltaX=0.2 CD0MachTableData=1.0, 1.2, 2.5, 1.8, 1.5 # Meaning: Mach = 0.6 → x1.0 CD0=0.015 Mach = 0.8 → x1.2 drag rising Mach = 1.0 → x2.5 transonic spike Mach = 1.2 → x1.8 supersonic relief Mach = 1.4 → x1.5 Note: XacMachTable is special: its Data are position shifts applied to Xac, not multipliers. ──────────────────────────────────────────────────────────────────── ------------------------- ALPHA TABLE (…AlphaTable) ------------------------- Purpose: model changes with angle of attack (α), e.g., stability fade or control “mush.” INI EXAMPLE (Cldc vs AoA) Cldc=0.012 CldcAlphaTableNumData=4 CldcAlphaTableStartX=0.0 # degrees CldcAlphaTableDeltaX=5.0 CldcAlphaTableData=1.0, 0.9, 0.6, 0.2 # Meaning: α=0° → ×1.0 100% α=5° → ×0.9 α=10° → ×0.6 α=15° → ×0.2 aileron nearly ineffective