Class Atmosphere

Standard atmosphere model implementing ISA (International Standard Atmosphere). Calculates atmospheric properties as functions of altitude including density, pressure, temperature, and speed of sound. Used by aerodynamic components to adjust lift, drag, and engine performance based on altitude.

Inheritance

object

Object

Component

Behaviour

MonoBehaviour

Atmosphere

Namespace: NWH.Aerodynamics.Environment

Assembly: NWH.Aerodynamics.dll

Syntax

[Serializable]
public class Atmosphere : MonoBehaviour

Remarks

Model is accurate up to 10,800 meters (troposphere). Uses standard day conditions at sea level:

• Temperature: 288.15 K (15 C)
• Pressure: 101,325 Pa
• Density: 1.225 kg/m3 Temperature decreases with altitude at standard lapse rate of 6.5 K/km. Density and pressure decrease exponentially with altitude affecting aerodynamic forces quadratically.

Fields

As

Atmospheric constant computed from gravity, molecular weight, and gas constant. Used in exponential pressure formula.

Declaration

[Tooltip("Constant.")]
public float As

Field Value

Type	Description
float

Cs

Speed of sound in m/s at current atmospheric conditions. Decreases with altitude as temperature drops. Used to calculate Mach number from airspeed.

Declaration

[Tooltip("Speed of sound [m/s]")]
public float Cs

Field Value

Type	Description
float

Gamma

Ratio of specific heats (Cp/Cv) for ideal diatomic gas. Used for speed of sound calculations.

Declaration

public const float Gamma = 1.4

Field Value

Type	Description
float

H

Geopotential height in meters. Accounts for gravitational variation with altitude. Used in atmospheric calculations.

Declaration

[Tooltip("Geopotential height [m]")]
public float H

Field Value

Type	Description
float

M

Mach number (ratio of airspeed to speed of sound). Dimensionless. Critical for compressibility effects above M 0.3.

Declaration

[Tooltip("Mach number")]
public float M

Field Value

Type	Description
float

M0

Mean molecular weight of air in kg/kmol. Assumes standard dry air composition.

Declaration

public const float M0 = 28.9644

Field Value

Type	Description
float

P

Current atmospheric pressure in Pascals. Decreases exponentially with altitude affecting engine performance and airspeed indicators.

Declaration

[Tooltip("Air pressure [Pa]")]
public float P

Field Value

Type	Description
float

P0

Sea level standard atmospheric pressure in Pascals (1 atm). Reference value for ISA calculations.

Declaration

[Tooltip("Air pressure at g0 [Pa]")]
public float P0

Field Value

Type	Description
float

R0

Earth radius at standard gravity location in meters. Used for geopotential height calculations.

Declaration

public const float R0 = 6356766

Field Value

Type	Description
float

Rs

Universal gas constant in Nm/(kmol K). Used in ideal gas law calculations.

Declaration

public const float Rs = 8314.32

Field Value

Type	Description
float

T

Current air temperature in Kelvin. Decreases linearly with altitude in troposphere at standard lapse rate.

Declaration

[Tooltip("Air temperature [K]")]
public float T

Field Value

Type	Description
float

T0

Sea level standard temperature in Kelvin (15 C). Reference value for ISA calculations.

Declaration

[Tooltip("Sea level temperature [K]")]
public float T0

Field Value

Type	Description
float

TL

Temperature lapse rate in K/m (6.5 K per 1000m). Rate at which temperature decreases with altitude in troposphere.

Declaration

[Tooltip("Temperature lapse rate [K]")]
public float TL

Field Value

Type	Description
float

Tc

Current air temperature in Celsius. Computed from T by subtracting Td (273.15 K).

Declaration

[Tooltip("Air temperature [C]")]
public float Tc

Field Value

Type	Description
float

Td

Zero degrees Celsius expressed in Kelvin (273.15). Used for temperature unit conversions.

Declaration

[Tooltip("Zero degrees C [K]")]
public float Td

Field Value

Type	Description
float

V

Free stream velocity (true airspeed) in m/s. Aircraft velocity relative to surrounding air mass. Used with speed of sound to compute Mach number.

Declaration

[Tooltip("Free stream velocity [m/s]")]
public float V

Field Value

Type	Description
float

Z

Geometric height (altitude) in meters above reference level. Input parameter for atmospheric calculations.

Declaration

[Tooltip("Geometric height [m]")]
public float Z

Field Value

Type	Description
float

g0

Gravitational acceleration in m/s^2. Defaults to standard gravity at 45 degrees latitude but reads from Physics.gravity at runtime.

Declaration

[Tooltip("Gravity at 45 deg lat [m/s^2]")]
public float g0

Field Value

Type	Description
float

rho

Current air density in kg/m3. Critical for all aerodynamic force calculations (varies quadratically with force). Decreases with altitude reducing lift, drag, and engine thrust.

Declaration

[Tooltip("Air density [kg/m^3]")]
public float rho

Field Value

Type	Description
float

rho0

Sea level standard air density in kg/m3. Reference value for ISA calculations and density ratio computations.

Declaration

[Tooltip("Air density at sea level [kg/m^3]")]
public float rho0

Field Value

Type	Description
float

rhoDefault

Default air density in kg/m3 used when Atmosphere component is not present. Represents sea level ISA conditions.

Declaration

public static float rhoDefault

Field Value

Type	Description
float

Methods

Calculate(float, float)

Updates all atmospheric properties based on current elevation and airspeed. Computes density, pressure, temperature, speed of sound, and Mach number using ISA model.

Declaration

public void Calculate(float elevation, float airspeed)

Parameters

Type	Name	Description
float	elevation	Geometric altitude in meters above reference level
float	airspeed	True airspeed in m/s (velocity relative to air mass)