55 lines
2.1 KiB
GDScript
55 lines
2.1 KiB
GDScript
extends Node
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@export var pressure_ASL := 101.325 # 1 atm. in kPa
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@export var density_ASL := 1.225 # at 288.15k in kg/m^3
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@export var temperature_ASL := 288.15 # surface temperature in Kelvin (288.15K = 15C)
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@export var tropopause_altitude := 11000.0 # meters above ASL
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@export var tropopause_temp := 216.65 # (216.65K = -56.5C)
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@export var gravity := 9.8 # here until I figure out the best way to get the project's default gravity.
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const AIR_MOLAR_MASS := 0.029 # kg/mol
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const GAS_CONSTANT := 8.31447
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const MACH_COEFF := 20.02948
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var pressure_constant: float
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var density_constant: float
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var temp_lapse_at_tropo: float # temperature lapse at troposphere, in K or C
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# Use this for initialization
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func _ready() -> void:
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_recalculate()
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func _recalculate() -> void:
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pressure_constant = (gravity * AIR_MOLAR_MASS) / (GAS_CONSTANT * temperature_ASL)
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density_constant = 1 / density_ASL
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temp_lapse_at_tropo = (temperature_ASL - tropopause_temp) / tropopause_altitude
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func pressure_by_alt(altitude: float, atm := false) -> float: # returns the pressure at altitude in kPa (default) or atm.
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var ret := exp(pressure_constant * altitude)
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if !atm:
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ret *= pressure_ASL
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return ret
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func density_by_alt(altitude: float, relative := false) -> float: # returns the density at altitude in kg/m^3 (default), or relative.
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var ret := pressure_by_alt(altitude) / (0.287058 * temperature_by_alt(altitude))
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if relative:
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ret *= density_constant
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return ret
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func temperature_by_alt(altitude: float) -> float:
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if altitude < tropopause_altitude:
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return temperature_ASL - altitude * temp_lapse_at_tropo
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else: # mesopause coming soon!
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return tropopause_temp
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func speed_of_sound_by_alt(altitude: float) -> float:
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return sqrt(temperature_by_alt(altitude)) * MACH_COEFF
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func mach_by_alt(altitude: float, speed: float) -> float:# a little bit expensive - use with caution
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return speed / speed_of_sound_by_alt(altitude)
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func atm_to_kPa(pressure: float) -> float:
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return pressure * pressure_ASL
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func kPa_to_atm(pressure: float) -> float:
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return pressure / pressure_ASL
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