Class AirfoilSection

Represents one spanwise section of an airfoil that calculates local aerodynamic forces. Each section independently computes lift, drag, and moment based on local flow conditions.

Inheritance

object

AirfoilSection

Namespace: NWH.Aerodynamics.Airfoils

Assembly: NWH.Aerodynamics.dll

Syntax

[Serializable]
public class AirfoilSection

Remarks

The finite wing is divided into multiple sections along the span. Each section evaluates the airfoil profile curves at its local angle of attack and applies forces at its aerodynamic center. Control surface deflections are integrated by combining the main airfoil section with its attached control section.

Constructors

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AirfoilSection()

Declaration

public AirfoilSection()

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AirfoilSection(string, Airfoil, FinitePlane, int)

Declaration

public AirfoilSection(string name, Airfoil parentAirfoil, FinitePlane fPlane, int subIndex = -1)

Parameters

Type	Name	Description
string	name
Airfoil	parentAirfoil
FinitePlane	fPlane
int	subIndex

Fields

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aT

Reference to the parent airfoil's transform system.

Declaration

public AirfoilTransform aT

Field Value

Type	Description
AirfoilTransform

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aerodynamicCenter

Local position of the aerodynamic center in the parent airfoil's coordinate system.

Declaration

public Vector3 aerodynamicCenter

Field Value

Type	Description
Vector3

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aoa

Current angle of attack in degrees. Angle between the relative wind and the chord line. Positive when wind comes from below the chord line.

Declaration

public float aoa

Field Value

Type	Description
float

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area

Planform area of this section in square meters. Used to scale aerodynamic forces.

Declaration

public float area

Field Value

Type	Description
float

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cd

Current drag coefficient evaluated from the airfoil profile at the current angle of attack.

Declaration

public float cd

Field Value

Type	Description
float

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chordLength

Average chord length of this section in meters. Distance from leading edge to trailing edge.

Declaration

public float chordLength

Field Value

Type	Description
float

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cl

Current lift coefficient evaluated from the airfoil profile at the current angle of attack.

Declaration

public float cl

Field Value

Type	Description
float

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cm

Current moment coefficient evaluated from the airfoil profile at the current angle of attack.

Declaration

public float cm

Field Value

Type	Description
float

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controlAirfoil

Reference to the control surface airfoil attached to this section, if any.

Declaration

public Airfoil controlAirfoil

Field Value

Type	Description
Airfoil

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controlAirfoilSectionIndex

Index of the control surface section that corresponds to this main wing section.

Declaration

public int controlAirfoilSectionIndex

Field Value

Type	Description
int

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dragCenter

Local position where drag force is applied in the parent airfoil's coordinate system.

Declaration

public Vector3 dragCenter

Field Value

Type	Description
Vector3

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dragForce

Drag force vector in world space. Points opposite to the relative wind direction.

Declaration

public Vector3 dragForce

Field Value

Type	Description
Vector3

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dragMagnitude

Magnitude of drag force in Newtons.

Declaration

public float dragMagnitude

Field Value

Type	Description
float

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fPlane

Defines the geometry of this section as a quadrilateral planform segment.

Declaration

public FinitePlane fPlane

Field Value

Type	Description
FinitePlane

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liftForce

Lift force vector in world space. Perpendicular to both relative wind and span direction.

Declaration

public Vector3 liftForce

Field Value

Type	Description
Vector3

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liftMagnitude

Magnitude of lift force in Newtons.

Declaration

public float liftMagnitude

Field Value

Type	Description
float

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momentMagnitude

Magnitude of pitching moment in Newton-meters.

Declaration

public float momentMagnitude

Field Value

Type	Description
float

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momentTorque

Moment torque vector in world space. Positive creates nose-up pitching moment.

Declaration

public Vector3 momentTorque

Field Value

Type	Description
Vector3

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name

Display name of this section for debugging purposes.

Declaration

public string name

Field Value

Type	Description
string

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parentAirfoil

Reference to the parent Airfoil that owns this section.

Declaration

public Airfoil parentAirfoil

Field Value

Type	Description
Airfoil

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subIndex

Section index within the parent airfoil's sections list.

Declaration

public int subIndex

Field Value

Type	Description
int

Properties

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AerodynamicCenter

Declaration

public Vector3 AerodynamicCenter { get; }

Property Value

Type	Description
Vector3

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ControlAirfoilSection

Declaration

public AirfoilSection ControlAirfoilSection { get; }

Property Value

Type	Description
AirfoilSection

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DragCenter

Declaration

public Vector3 DragCenter { get; }

Property Value

Type	Description
Vector3

Methods

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DrawGizmos()

Declaration

public void DrawGizmos()

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Initialize(Airfoil, Atmosphere)

Initializes the section's geometry and calculates its area, chord length, and force application points.

Declaration

public void Initialize(Airfoil inParentAirfoil, Atmosphere atmosphere)

Parameters

Type	Name	Description
Airfoil	inParentAirfoil	The Airfoil that owns this section.
Atmosphere	atmosphere	Optional Atmosphere component for altitude-dependent air density.

Remarks

Computes the aerodynamic center and drag center positions along the chord line based on the parent airfoil's specified chord position ratios. Calculates the average chord length from the leading and trailing edge lengths.

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OnPhysicsSubstep(float)

Calculates and applies lift, drag, and moment forces to the parent rigidbody.

Declaration

public void OnPhysicsSubstep(float dt)

Parameters

Type	Name	Description
float	dt	Physics timestep in seconds.

Remarks

Evaluates the airfoil profile curves at the current angle of attack to obtain Cl, Cd, and Cm. Forces are calculated using the standard aerodynamic equations with dynamic pressure (0.5 * rho * v^2 * area). Lift is applied at the aerodynamic center, drag at the drag center. Moment is applied as a force couple perpendicular to the chord line.

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OnPrePhysicsSubstep(float)

Pre-calculates flow conditions and control surface effects before force calculation.

Declaration

public void OnPrePhysicsSubstep(float dt)

Parameters

Type	Name	Description
float	dt	Physics timestep in seconds.

Remarks

Computes the relative airflow velocity by combining the rigidbody's velocity at the aerodynamic center with wind velocity. If the relative velocity is below 0.1 m/s, skips force calculation for performance. When a control surface is attached, calculates the effective angle of attack and chord length based on the control surface deflection angle.

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SetWindVelocity(Vector3)

Sets the ambient wind velocity affecting this section.

Declaration

public void SetWindVelocity(Vector3 vel)

Parameters

Type	Name	Description
Vector3	vel	Wind velocity vector in world space.