This can be used to enable (1, TRUE) or disable (0, FALSE) the use of CFD within the simulation.

Default value is 0 (FALSE).

For more information, please see here: Debug Aircraft CFD.

This can be used to enable (1, TRUE) or disable (0, FALSE) the reinjection of the CFD output with that of the flight model, specifically affecting the airframe surface. Note that this needs to be set to 1 (TRUE) for CFD_ReinjectRotors, CFD_ReinjectVTailX, and CFD_ReinjectHTailY to work as well. If this is 0 (FALSE), then those parameters will have no effect.

Default value is 0 (FALSE).

For more information, please see here: Debug Aircraft CFD.

This can be used to enable (1, TRUE) or disable (0, FALSE) the re-injection of the CFD output with that of the flight model for rotors/propellers. Note that this parameter will have no effect if the CFD_ReinjectBody parameter is not set to 1 (TRUE).

Default value is 0 (FALSE).

For more information, please see here: Debug Aircraft CFD.
IMPORTANT! This requires that you have the prop_mod_use_modern parameter set to 1 (TRUE).

This can be used to enable (1, TRUE) or disable (0, FALSE) the re-injection of the CFD output with that of the flight model, specifically affecting the tail control surfaces. Note that this parameter will have no effect if the CFD_ReinjectBody parameter is not set to 1 (TRUE).

Default value is 0 (FALSE).

For more information, please see here: Debug Aircraft CFD.

This can be used to enable (1, TRUE) or disable (0, FALSE) the re-injection of the CFD output with that of the flight model, specifically affecting the tail control surfaces. Note that this parameter will have no effect if the CFD_ReinjectBody parameter is not set to 1 (TRUE).

Default value is 0 (FALSE).

For more information, please see here: Debug Aircraft CFD.

Set the air incompressibility when the CFD simulation is active. This is essentially the divergence term of the the Navier Stokes equations used by the CFD simulation, and sets the rate at which the pressure of a voxel will be impacted by the local divergence.

Default value is 1.0, and the value will only be used when the CFD_EnableSimulation parameter is set to 1 (TRUE).

For more information, please see here: Debug Aircraft CFD.

Set the scale of the voxel volume for CFD simulation. At 1, this will create a volume that is 150% that of the aircraft wingspan, and the volume will be comprised of n³ voxels (where n is set by the CFD_VoxelNbVoxels parameter).

Default value is 1.0, and the value will only be used when the CFD_EnableSimulation parameter is set to 1 (TRUE).

For more information, please see here: Debug Aircraft CFD.

This can be used to set the number of voxels that will be cubed to make the sample volume for the CFD simulation.

IMPORTANT! This may have a serious impact on performance if set to values greater than the default value, due to it currently having a time complexity of O(n3).

Default value is 20.0, and the value will only be used when the CFD_EnableSimulation parameter is set to 1 (TRUE).

For more information, please see here: Debug Aircraft CFD.

This parameter allows you to offset the ground collision vertically by N voxels. With a value of 0 voxels, the ground collision lets the air penetrate up to 1 voxel into the ground, ie: the ground is a "soft collision layer" of about 1 voxel thickness that starts at ground level and ends 1 voxel into the ground. By setting this to 1 voxel, the soft ground collision starts 1 voxel above the ground and stops airflow before it touches the ground. Adjusting this value will have an impact on the strength of the ground effect that is applied on the aircraft. It is worth noting that ground effect is calculated taking into account the ground conditions, so things like icing will have an effect on the drag and lift.

Default value is 0.0, and the value will only be used when the CFD_EnableSimulation parameter is set to 1 (TRUE).

For more information, please see here: Debug Aircraft CFD.

Defines how much lift will be added to the overall lift formula based on the current pitch rotation speed.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section.

Defines how much lift will be added to the overall lift formula based on the current angle of attack variation rate.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section.

Defines how much lift will be added to the overall lift formula based on the current elevator deflection angle.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section.

Defines how much lift will be added to the overall lift formula based on the current yaw angle of the aircraft.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section.

Defines the lift coefficient that will be added to the target lift coefficient obtained with the lift_coef_aoa_table of the aircraft when at maximum spoiler expansion on the ground. This allows you to correctly tune the spoilers for ground usage where there is very strong drag and very strong loss in lift. Essentially this is the coefficient for the deflection of 1 radian.

The lift value is multiplied by the spoiler deflection in radians, so this coefficient is necessary to compensate for the scale by the deflection angle (also in radians), in order to reach 100%.

NOTE: This value will also be used when the aircraft is airborne, unless the lift_coef_air_spoilers value is set.

Defines the lift coefficient that will be added to the target lift coefficient obtained with the lift_coef_aoa_table of the aircraft when at maximum spoiler expansion in the air. This allows to correctly tune the spoiler behaviour in the air where you have strong drag, and little loss in lift. The lift value is multiplied by the spoiler deflection in radians, so this coefficient is necessary to compensate for the scale by the deflection angle (also in radians), in order to reach 100%.

NOTE: This value overrides the value set by lift_coef_spoilers. 

Defines the target drag of the airplane in clean configuration (ie: no propeller, no turbulence, no engine wash, no gears, no flaps, no spoilers, no deflections...), when there is zero lift. This is usually also called the \(C_{D0}\) or \(C_{DZeroLift}\). Zero lift may occur at an angle of attack of zero - reason for which \(C_{D0}\) is sometimes the drag at an AoA of 0 - but most of the time, zero lift occurs at an angle of attack that is negative and the \(C_{D0}\) does not correspond to the drag at AoA 0.

In the legacy FSX flight model, this defines the actual \(C_{D0}\). In the modern flight model, this defines the target \(C_{D0}\) that will be distributed over all the surfaces of the aircraft when building the airplane used in the aerodynamic surface simulation. Once the aircraft is built, it will then be normalized to match exactly the target \(C_{D0}\).

Defines the drag of the gears that will be applied at the location of the gear contact points and create the appropriate angular moment.

If the aircraft features retractable gears, this coefficient will be zero once the gears are retracted. For non retractable gears this will always be present. All aircraft which feature gears, retractable or not, should define a drag coefficient for gears. This drag coefficient should not be baked into the drag_coef_zero_lift otherwise the gear angular moment calculations will be wrong. Also note that if the aircraft has no landing gear, this value will STILL have an effect and as such should be set to 0 in those cases.

Defines the target drag added when spoilers are fully extended on the ground, where there is very strong drag and very strong loss in lift. The drag value is multiplied by the spoiler deflection in radians, so this coefficient is necessary to compensate for the scale by the deflection angle (also in radians), in order to reach 100%.

NOTE: This value will also be used when the aircraft is airborne, unless the drag_coef_air_spoilers value is set.In the legacy FSX flight model, this defines the actual flap drag. In the modern flight model, this defines the target spoiler drag that will be distributed over all the spoiler surfaces of the aircraft when building the airplane used in the aerodynamic surface simulation. Once the aircraft is built, it will then be normalized to match exactly the target spoiler drag.

Defines the target drag added when spoilers are fully extended in the air, where you have strong drag, and little loss in lift. The drag value is multiplied by the spoiler deflection in radians, so this coefficient is necessary to compensate for the scale by the deflection angle (also in radians), in order to reach 100%.

NOTE: This value overrides the value set by drag_coef_spoilers. 

Ratio of the stall AoA at which the airflow will start detaching from the wing.

Default value is: 0.9

Ratio of the stall AoA at which the airflow will be completely detached from the wing.

Default value is: 1.1

Power of the ratio curve that controls the airflow detaching from the wing between start and end.

Default value is: 0.8

In Radians, minimum angle between the stall AoA at which the airflow starts detaching and at which it is fully detached.

Default value is: 0.025

In ratios per second, speed at which the airflow will be detaching.

Default value is: 1.0

In ratios per second, speed at which the airflow will be attaching.

Default value is: 1.0

Degrees added to the stall AoA at the ailerons.

Default value is: 0.0

Degrees added to the stall AoA at the wingtips.

Default value is: 2.0

Virtual added wing twist to reduce stall at the wingtips.

Default value is: 2.5

Scale ratio of the virtual added wing twist.

Default value is: 0.9

This parameter sets the rigidity of the fuselage. If set to -1 then the fuselage will be considered as having "infinite" rigidity, while values greater than 0 will mean that applied forces will affect the airframe. The approximate value for this parameter can be calculated as follows:

• fuselage_rigidity = distance from the CG in ft at which a force applied yields 50% of it's effect on the entire airframe after 1 second.

Note that low rigidity will increase the aircraft oscillations, and if the rigidity is low enough for the time accumulation to correspond to the oscillation frequency, then you can even get a situation of resonance that will cause the entire airframe to "flutter" wildly.

Default value is -1, and the value is in ft.

This parameter sets the inertia for the fuselage, and works in harmony with the fuselage_rigidity parameter. However, if that parameter is less than or equal to zero, then this parameter will have no effect. Generally you want to set this to 1 to start with then tweak it up or down to get the aircraft behaviour that you require.

Default value is 1.

Defines how much side force will be generated when the yaw angle is non zero (during a side slip).

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use fuselage_lateral_cx to modify the side drag coefficient of the fuselage and rudder_lift_coef to modify the forces generated by the rudder.

Defines how much side force will be generated when the aircraft has some roll speed (during a roll).

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, the side force resulting from a roll is a complex combination of the effect of all the aircraft surfaces that cannot be directly controlled. Making sure the aircraft surfaces are correctly aligned and feature correct areas and coefficients will result in a realistic side force when rolling.

Defines how much side force will be generated when the yaw angle is changing.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use fuselage_lateral_cx to modify the side drag coefficient of the fuselage and rudder_lift_coef to modify the forces generated by the rudder.

Defines how much side force will be generated when the rudder is deflected.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use rudder_lift_coef to modify the forces generated by the rudder deflection.

Defines how much pitch moment will be generated when the aircraft is yawing.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use the rudder trim and, rudder area and rudder vertical position to modify the pitch moment generated generated by the rudder at zero deflection.

Defines how much pitch moment will be generated when the elevator is deflected.

This is a legacy FSX parameter and the actual value here is not normally used in the modern flight model, but the sign of the value is used and it is necessary to set a value other than 0 for the autopilot (see the notes below). In the modern flight model the effect that this parameter is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use the elevator_lift_coef, elevator longitudinal position and elevator area to adjust this effect.

NOTE: The absolute value of this parameter is ignored by the modern flight model but it's sign is used to invert the elevator input angle when it is negative. This may be useful for aircraft that need an inverted elevator (elevator in the front).

NOTE: Even in the modern flight model, the autopilot system may still use this variable to calculate the elevator deflection necessary to find a required pitch moment. The PID will usually compensate for wrong values, but this variable cannot be set to zero or very far off and must be relatively close to reality. You can use the legacy flight model tool to calculate the correct value that will then usually work with the autopilot.

Defines how much pitch moment will be generated when the elevator trim is deflected.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use the elevator_lift_coef, elevator longitudinal position and elevator area and scale the trim effect to adjust this effect.

Defines how much the pitch velocity will be dampened when the plane is pitching.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use the elevator_lift_coef, elevator longitudinal position, fuselage_lateral_cx, and elevator area to adjust this effect. The wings and even the rudder may also contribute to this effect.

Defines how much the pitch moment will be generated at AoA 0.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use the htail_incidence as the primary variable to impact the 0 AoA pitch moment.

Defines how much the alpha velocity will be dampened when the plane is changing incidence.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use the elevator_lift_coef, elevator longitudinal position, fuselage_lateral_cx and elevator area to adjust this effect. The wings and even the rudder may also contribute to this effect.

Defines how much pitch moment will be generated when the flaps will be deflected.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, refer to the flaps documentation to see how to move the flap lift on the longitudinal axis in order to control the pitch moment at each flap level.

Defines how much the pitch moment will be generated because of the gears.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use the drag_coef_gear and the position of the gear contact points to change the angular moments generated by gears.

Defines how much pitch moment will be generated when the spoilers will be deflected.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, this will be automatically simulated and there is no way yet to change the pitch moment generated by spoilers. It will be an automatic effect of the spoiler deflection and mostly dependent on the drag generated by the spoilers and the vertical position of the wings.

Defines how much pitch moment will be generated when the elevator is deflected and there is a propeller spinning (prop wash).

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model this is automatically simulated based on how air is accelerated by the propeller and blown onto the control surfaces. However one can use the elevator_lift_coef, elevator longitudinal position and elevator area to adjust this effect. In the modern flight model, this effect only works if the propeller is blowing air onto the control surfaces. If the propeller is under a wing, far from any surface, this effect will not occur.

Defines how much pitch moment will be generated when the plane is pitching and there is a propeller spinning (prop wash).

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model this is automatically simulated based on how air is accelerated by the propeller and blown onto the control surfaces. However one can use the elevator_lift_coef, elevator longitudinal position and elevator area to adjust this effect. In the modern flight model, this effect only works if the propeller is blowing air onto the control surfaces. If the propeller is under a wing, far from any surface, this effect will not occur.

Defines how much roll moment will be generated when the aircraft is yawing or side slipping.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, most of the roll will be induced by the difference in lift between one wing and the other, and the rudder will work against this effect. Adjust the shape of the wing via wing_sweep, wing_dihedral, wing_twist, wing_camber, the position of the wing, and the vertical position of the rudder, the rudder area and rudder lift coefficient to adjust this effect. Some of these parameters will work against each other. Induced roll is a very complex effect to balance which will depend on many factors.

Defines how much the roll speed will be dampened based on the current roll speed.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, most of the roll damping will be the result of the wings, the elevator and the rudder resisting roll. You can also use roll_stability and roll_gyro_stability to add more roll damping.

Defines how much roll moment will be generated when the aircraft is rotating around the yaw axis.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, most of the roll will be induced by the difference in lift between one wing and the other, and the rudder will work against this effect. Adjust the shape of the wing via wing_sweep, wing_dihedral, wing_twist, wing_camber, the position of the wing, and the vertical position of the rudder, the rudder area and rudder lift coefficient to adjust this effect. Some of these parameters will work against each others. Induced roll is a very complex effect to balance which will depend on many factors.

Defines how much roll moment will be generated when the spoilers will be deflected.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, this will be automatically simulated and there is no way yet to change the roll moment generated by spoilers.

Defines how much roll moment will be generated when the ailerons are deflected.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use the aileron_span_outboard, aileron_effectiveness and the aileron up and down angles to control this effect.

Defines how much roll moment will be generated when the rudder is deflected.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, most of the roll will be induced by the difference in lift between one wing and the other, and the rudder will work against this effect. Adjust the shape of the wing via wing_sweep, wing_dihedral, wing_twist, wing_camber, the position of the wing, and the vertical position of the rudder, the rudder area and rudder lift coefficient to adjust this effect. Some of these parameters will work against each other. Induced roll is a very complex effect to balance which will depend on many factors.

Defines how much roll moment will be generated when the aileron trim is are deflected.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use the aileron_span_outboard, aileron_trim_effectiveness and aileron up and down angles to control this effect.

Defines how much yaw moment will be generated when the aircraft is yawing or side slipping.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use fuselage_lateral_cx to modify the side drag coefficient of the fuselage and rudder_lift_coef to modify the forces generated by the rudder. The longitudinal position of the fuselage and rudder will have a big impact on the yaw moment. If most of the fuselage is behind the CG, the fuselage will have a stabilizing effect.

Defines how much yaw moment will be generated when the aircraft has some roll speed (during a roll).

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, the yaw moment resulting from a roll is a complex combination of the effect of all the aircraft surfaces that cannot be directly controlled. Adjusting the rudder surface parameters will have the largest effect here but the wing will have an effect too. Making sure the aircraft surfaces are correctly aligned and feature correct areas and coefficients will result in a realistic yaw moment when rolling.

Defines how much the yaw speed will be dampened based on the current yaw speed.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, most of the yaw damping will be the result of the rudder and fuselage, but the wings contribute as well. You can also use yaw_stability and yaw_gyro_stability to add more yaw damping.

Defines how much yaw moment will be generated when the plane is yawing and there is a propeller spinning (prop wash).

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model this is automatically simulated based on how air is accelerated by the propeller and blown onto the control surfaces. However one can use the rudder_lift_coef, rudder longitudinal position and rudder area to adjust this effect. In the modern flight model, this effect only works if the propeller is blowing air onto the control surfaces. If the propeller is under a wing, far from any surface, this effect will automatically not occur.

Defines how much yaw moment will be generated when the ailerons are deflected.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, this will mostly be caused by a difference in drag between both wings because of the difference in airspeed between both wings and the difference in deflection of both ailerons. Use the aileron_up_drag_coef, aileron_down_drag_coef and aileron up & down angles to control this effect.

Defines how much yaw moment will be generated when the rudder is deflected.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use rudder_lift_coef to modify the moment generated by the rudder deflection. The longitudinal position of the rudder also plays an important role.

Defines how much yaw moment will be generated when the plane rudder is deflected and there is a propeller spinning (prop wash).

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model this is automatically simulated based on how air is accelerated by the propeller and blown onto the control surfaces. However one can use the rudder_lift_coef, rudder longitudinal position and rudder area to adjust this effect. In the modern flight model, this effect only works if the propeller is blowing air onto the control surfaces. If the propeller is under a wing, far from any surface, this effect will automatically not occur.

Defines how much yaw moment will be generated when the rudder trim is are deflected.

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, use the rudder_trim_effectiveness, rudder area and rudder max deflection to control this.

Defines if the aerodynamic center longitudinal position should be placed computationally or manually. In legacy FSX, the aerodynamic center was in a constant position and computed based on the pitch moment data and moment of inertia values. This would still work with the modern flight model, but we recommend disabling the computation of the aerodynamic center - setting it to 0 (FALSE) - and positioning this manually with aero_center_lift.

When compute_aero_center is set to 0 (FALSE) this variable allows you to define the longitudinal position of the aerodynamic center, expressed in ft. The modern flight model does not force the position of the aerodynamic center during the simulation because the aerodynamic center is not static in this flight model - it is calculated as the result of complex pressure forces applied on the surfaces, which actually causes a moving aerodynamic center. It is, however, usually very close to 25% and will normally move between 20% and 30%. So, we use this variable to longitudinally align the wing surfaces with the wing geometry, considering that the aerodynamic center is located at 25% MAC. Again, this does not mean that the aero center will then stay at 25% MAC during the simulation, it will just be used to initialize the surface position once at start.

IMPORTANT! This is positioned relative to the (0,0,0) position in the 3D model reference, not the Reference Datum position.

Defines the drag added by upwards aileron deflection. This parameter has a significant impact on adverse yaw. Reduce upward deflection drag to get more adverse yaw. This parameter is multiplied by the aileron deflection angle and internal coefficients.

Default is 0.5. This can be scaled with the aileron_up_drag_scalar parameter in the [FLIGHT_TUNING] section and is further modified by internal coefficients.

Defines the drag added by upwards aileron deflection. This parameter has a significant impact on adverse yaw. Increase downward deflection drag to get more adverse yaw. This parameter is multiplied by the aileron deflection angle.

Default is 1. This can be scaled with the aileron_down_drag_scalar parameter in the [FLIGHT_TUNING] section and is further modified by internal coefficients.

Defines the lift coefficient slope of the elevator control surface. This will have a direct impact on elevator authority and pitch stability. The elevator lift coefficient slope is usually dependent on the elevator aspect ratio.

Default is 5.0, and generally values will always fall between 1.0 and 5.0, with a theoretical maximum of 2𝝅 and a recommended value between 2.0 (for less authority and stability) and 5.0 (for more authority and stability). This can be scaled with the elevator_effectiveness parameter in the [FLIGHT_TUNING] section.

Defines the lift coefficient slope of the rudder control surface. This will have a direct impact on rudder authority, yaw stability, adverse yaw and induced roll. The rudder lift coefficient slope is usually dependent on the rudder aspect ratio.

Default is 5.0, and generally values will always fall between 1.0 and 5.0, with a theoretical maximum of 2𝝅 and a recommended value between 2.0 (for less authority and stability) and 5.0 (for more authority and stability). This can be scaled with the rudder_effectiveness parameter in the [FLIGHT_TUNING] section.

This table allows you to define the AoA polar (in radians) against the clean aircraft lift coefficient. The AoA vs. lift table defines how much lift the aircraft generates at various AoAs. The table has a maximum of 47 entries with the following format:

AoA_alpha:lift_coef,
AoA_alpha:lift_coef,
AoA_alpha:lift_coef,
etc...

In the modern flight model, this is used during the aircraft surfaces construction as a lift target that the aircraft should achieve at various angles of attack. This will impact the wing surfaces only, but the total lift will consider all surfaces. It describes the lift in clean configuration (ie: zero slip, no propeller, no gears, no control surface deflection). Once the aircraft is created, if will be normalized so that the effective lift coefficients measured actually match the target lift coefficients.

NOTE: The lift coefficients are only matched between AoAs 0 and the stall AoA. For other AoAs all around the 360° of the polar, it will be a natural consequence of the setup of the aerodynamic surfaces and other parameters. The polar does not need to be accurately defined in detail for AoAs outside of the -10° to stall +10° range in this table.

This table allows you to scale the ground effect intensity. This defines the maximum ground effect on the lift component but will impact the maximum effect on the induced drag component proportionally as well. Even though this table allows you to define the ground effect at various mach levels, it is the primary way to set the ground effect intensity. The table has a maximum of 11 entries and the format:

mach:lift_coef,
mach:lift_coef,
mach:lift_coef,
etc...

Scales the lift coefficient based on the mach level. The table permits a maximum of 17 entries and has the following format:

mach:lift_coef,
mach:lift_coef,
mach:lift_coef,
etc...

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section.

2D Table of Floats

Scales the delta elevator lift coefficient based on the mach level. The table has a maximum of 17 entries and the format:

mach:lift_coef,
mach:lift_coef,
mach:lift_coef,
etc...

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section.

2D Table of Floats

Scales the lift coefficient impacted by the change in AoA based on the mach level. The table has a maximum of 17 entries and the format:

mach:lift_coef,
mach:lift_coef,
mach:lift_coef,
etc...

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, the lift coefficient at higher mach levels is automatically impacted by a progressive detaching of the laminar airflow over the surfaces.

2D Table of Floats

Scales the lift coefficient impacted by the change in pitch based on the mach level. The table has a maximum of 17 entries and the format:

mach:lift_coef,
mach:lift_coef,
mach:lift_coef,
etc...

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, the lift coefficient at higher mach levels is automatically impacted by a progressive detaching of the laminar airflow over the surfaces.

2D Table of Floats

Scales the lift coefficient impacted by the change in yaw based on the mach level. The table has a maximum of 17 entries and the format:

mach:lift_coef,
mach:lift_coef,
mach:lift_coef,
etc...

This is a legacy FSX parameter not used in the modern flight model. In the modern flight model this effect is natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section. In the modern flight model, the lift coefficient at higher mach levels is automatically impacted by a progressive detaching of the laminar airflow over the surfaces.

2D Table of Floats

Adds drag based on the mach level. In the modern flight model, the drag coefficient at higher mach levels is automatically impacted by a progressive detaching of the laminar airflow over the surfaces. However this table allows to add more drag at specific mach levels to simulate a mach wall or specific effects of drag due to turbulence at specific drag levels. Drag walls are not natively simulated yet and will need to be defined with this table. The table has a maximum of 17 entries and the format:

mach:drag_coef,
mach:drag_coef,
mach:drag_coef,
etc...

2D Table of Floats

2D Table of Floats

2D Table of Floats

2D Table of Floats

2D Table of Floats

Influence CoL computation if not prescribed

Legacy FSX table, not used in the modern flight model.

2D Table of Floats

AoA(alpha) is given in DEGREES

Legacy FSX table, not used in the modern flight model.

2D Table of Floats

AoA(alpha) is given in DEGREES

Legacy FSX table, not used in the modern flight model.

2D Table of Floats

AoA(alpha) is given in DEGREES

Legacy FSX table, not used in the modern flight model.

2D Table of Floats

AoA(alpha) is given in DEGREES

Legacy FSX table, not used in the modern flight model.

2D Table of Floats

\({C_L}\) (roll moment coefficient) versus AoA-

Legacy FSX table, not used in the modern flight model.

\({C_n}\) (yaw moment coef) versus AoA.

Legacy FSX table, not used in the modern flight model.

Allows you to define a non linear elevator deflection curve on top of the input curve settings possible in the simulator. The table defines how the input value is scaled for each range of input values. The table has the following format (maximum 17 value pairs):

elevator_angle:scale,
elevator_angle:scale,
elevator_angle:scale,
etc...

Default is to scale all input values by 1, and that the angles should be expressed in radians.

Allows to define a non linear aileron deflection curve on top of the input curve settings possible in the simulator. The table defines how the input value is scaled for each range of input values. The table has the following format (maximum 17 value pairs):

aileron_angle:scale,
aileron_angle:scale,
aileron_angle:scale,
etc...

Default is to scale all input values by 1, and that the angles should be expressed in radians.

Allows to define a non linear rudder deflection curve on top of the input curve settings possible in the simulator. The table defines how the input value is scaled for each range of input values. The table has the following format (maximum 17 value pairs):

rudder_angle:scale,
rudder_angle:scale,
rudder_angle:scale,
etc...

Default is to scale all input values by 1, and that the angles should be expressed in radians.

Scaling of roll_moment_delta_aileron versus gravity forces.

Legacy FSX table, not used in the modern flight model.

When building the surfaces of the aircraft, the modern flight model allows us to use the following drag formula:

\({C_D} = {C_{D0}} + K(C_L - C_{L0})^{2}\)

This parameter represents the \({C_{L0}}\) parameter of this formula in the clean configuration. The aircraft is built trying to match this drag polar and then a normalization pass is done on all surfaces to perfectly match the target polar. This parameter has also been added to the legacy FSX flight model that now also allows \({C_{D0}}\) to not be always zero.

When building the surfaces of the aircraft, the modern flight model allows us to use the following drag formula:

\({C_D} = {C_{D0}} + K(C_L - C_{L0})^{2}\)

This parameter represents the \({C_{L0}}\) parameter of this formula in the landing configuration with flaps fully deployed. The aircraft is built trying to match this drag polar and then a normalization pass is done on all surfaces to perfectly match the target polar. This parameter has also been added to the legacy FSX flight model that now also allows \({C_{D0}}\) to not be always zero.

Defines the perpendicular drag coefficient of the fuselage, which occurs when the airflow is going perpendicular to the front axis (ie: sideways - left to right or right to left) but also going up and down. This coefficient has an impact on drag when side slipping, as well as a general impact on yaw stability and pitch stability. Faster aircraft with a larger reynolds number should usually have a larger lateral fuselage \(C_x\).

Please note that the drag calculation supposes that the fuselage shape seen from the side has the shape of a rectangle with skewed front and rear tips. A larger or smaller \(C_x\) may be necessary to compensate for different fuselage shapes. If the fuselage has edges and is different from a perfect cylinder, the \(C_x\) should be higher. If the fuselage's area, when seen from the side, is smaller than the area of a skewed rectangle, the \(C_x\) should be smaller to compensate. A longer aircraft, with a higher l/d ratio, will have a higher \(C_x\). A shorter aircraft with a smaller l/d ratio, will have a smaller \(C_x\). Therefore, when chosing a \(C_x\) it is important to consider the reynolds number and l/d ratio of the fuselage.

Default is 0.4 - which is approximately the lateral drag of a cylinder with a reynolds number of a small aicraft and a l/d ratio of about 5, compensated for the shape of most small aircraft fuselages. The value should usually fall between 0.2 and 1.2 for most aircraft (with a "soft" limit of 2, which would essentially be a box).