#include "math.h"

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Enumerations
enum	AIRSPEED_SENSOR_MODEL { AIRSPEED_SENSOR_MODEL_MEMBRANE = 0, AIRSPEED_SENSOR_MODEL_SDP3X }

enum	AIRSPEED_COMPENSATION_MODEL { AIRSPEED_COMPENSATION_MODEL_PITOT = 0, AIRSPEED_COMPENSATION_MODEL_NO_PITOT = 1, AIRSPEED_COMPENSATION_TUBE_PRESSURE_LOSS = 2 }

Functions
__EXPORT float	calc_IAS_corrected (enum AIRSPEED_COMPENSATION_MODEL pmodel, enum AIRSPEED_SENSOR_MODEL smodel, float tube_len, float tube_dia_mm, float differential_pressure, float pressure_ambient, float temperature_celsius)
	Calculate indicated airspeed (IAS). More...

__EXPORT float	calc_IAS (float differential_pressure)
	Calculate indicated airspeed (IAS). More...

__EXPORT float	calc_TAS_from_EAS (float speed_indicated, float pressure_ambient, float temperature_celsius)
	Calculate true airspeed (TAS) from equivalent airspeed (EAS). More...

__EXPORT float	calc_EAS_from_IAS (float speed_indicated, float scale)
	Calculate equivalent airspeed (EAS) from indicated airspeed (IAS). More...

__EXPORT float	calc_TAS (float total_pressure, float static_pressure, float temperature_celsius)
	Directly calculate true airspeed (TAS) More...

__EXPORT float	get_air_density (float static_pressure, float temperature_celsius)
	Calculates air density. More...

__EXPORT float	calc_EAS_from_TAS (float speed_true, float pressure_ambient, float temperature_celsius)
	Calculate equivalent airspeed (EAS) from true airspeed (TAS). More...

Enumeration Type Documentation

◆ AIRSPEED_COMPENSATION_MODEL

enum AIRSPEED_COMPENSATION_MODEL

Enumerator
AIRSPEED_COMPENSATION_MODEL_PITOT
AIRSPEED_COMPENSATION_MODEL_NO_PITOT
AIRSPEED_COMPENSATION_TUBE_PRESSURE_LOSS

Definition at line 54 of file airspeed.h.

◆ AIRSPEED_SENSOR_MODEL

enum AIRSPEED_SENSOR_MODEL

Enumerator
AIRSPEED_SENSOR_MODEL_MEMBRANE
AIRSPEED_SENSOR_MODEL_SDP3X

Definition at line 49 of file airspeed.h.

Function Documentation

◆ calc_EAS_from_IAS()

__EXPORT float calc_EAS_from_IAS	(	float	speed_indicated,
		float	scale
	)

Calculate equivalent airspeed (EAS) from indicated airspeed (IAS).

Note that we neglect the conversion from CAS (calibrated airspeed) to EAS.

Parameters

speed_indicated	current indicated airspeed
scale	scale from IAS to CAS (accounting for instrument and pitot position erros)

Returns: EAS in m/s

Definition at line 232 of file airspeed.cpp.

Referenced by MavlinkReceiver::handle_message_hil_sensor(), and AirspeedValidator::update_EAS_TAS().

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◆ calc_EAS_from_TAS()

__EXPORT float calc_EAS_from_TAS	(	float	speed_true,
		float	pressure_ambient,
		float	temperature_celsius
	)

Calculate equivalent airspeed (EAS) from true airspeed (TAS).

It is the inverse function to calc_TAS_from_EAS()

Parameters

speed_true	current true airspeed
pressure_ambient	pressure at the side of the tube/airplane
temperature_celsius	air temperature in degrees celcius

Returns: EAS in m/s

Definition at line 282 of file airspeed.cpp.

References CONSTANTS_AIR_DENSITY_SEA_LEVEL_15C, and get_air_density().

Referenced by AirspeedModule::update_ground_minus_wind_airspeed().

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◆ calc_IAS()

__EXPORT float calc_IAS ( float differential_pressure )

Calculate indicated airspeed (IAS).

Note that the indicated airspeed is not the true airspeed because it lacks the air density compensation. Use the calc_true_airspeed functions to get the true airspeed.

Parameters

total_pressure	pressure inside the pitot/prandtl tube
static_pressure	pressure at the side of the tube/airplane

Returns: indicated airspeed in m/s

Note that the indicated airspeed is not the true airspeed because it lacks the air density and instrument error compensation.

Parameters

differential_pressure total_ pressure - static pressure

Returns: IAS in m/s

Definition at line 195 of file airspeed.cpp.

References CONSTANTS_AIR_DENSITY_SEA_LEVEL_15C, and f().

Referenced by MavlinkReceiver::handle_message_hil_sensor().

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◆ calc_IAS_corrected()

__EXPORT float calc_IAS_corrected	(	enum AIRSPEED_COMPENSATION_MODEL	pmodel,
		enum AIRSPEED_SENSOR_MODEL	smodel,
		float	tube_len,
		float	tube_dia_mm,
		float	differential_pressure,
		float	pressure_ambient,
		float	temperature_celsius
	)

Calculate indicated airspeed (IAS).

Note that the indicated airspeed is not the true airspeed because it lacks the air density compensation. Use the calc_true_airspeed functions to get the true airspeed.

Parameters

total_pressure	pressure inside the pitot/prandtl tube
static_pressure	pressure at the side of the tube/airplane

Returns: indicated airspeed in m/s

Calculate indicated airspeed (IAS).

Note that the indicated airspeed is not the true airspeed because it lacks the air density compensation. Use the calc_true_airspeed functions to get the true airspeed.

Parameters

differential_pressure total_ pressure - static pressure

Returns: indicated airspeed in m/s

Definition at line 58 of file airspeed.cpp.

References AIRSPEED_COMPENSATION_MODEL_NO_PITOT, AIRSPEED_COMPENSATION_MODEL_PITOT, AIRSPEED_COMPENSATION_TUBE_PRESSURE_LOSS, AIRSPEED_SENSOR_MODEL_MEMBRANE, AIRSPEED_SENSOR_MODEL_SDP3X, CONSTANTS_AIR_DENSITY_SEA_LEVEL_15C, f(), get_air_density(), and M_PI_F.

Referenced by Sensors::diff_pres_poll().

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◆ calc_TAS()

__EXPORT float calc_TAS	(	float	total_pressure,
		float	static_pressure,
		float	temperature_celsius
	)

Directly calculate true airspeed (TAS)

Here we assume to have no instrument or pitot position error (IAS = CAS), and neglect the CAS to EAS conversion (CAS = EAS). Note that the true airspeed is NOT the groundspeed, because of the effects of wind.

Parameters

total_pressure	pressure inside the pitot/prandtl tube
static_pressure	pressure at the side of the tube/airplane
temperature_celsius	air temperature in degrees celcius

Returns: true airspeed in m/s

Definition at line 249 of file airspeed.cpp.

References CONSTANTS_AIR_DENSITY_SEA_LEVEL_15C, f(), and get_air_density().

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◆ calc_TAS_from_EAS()

__EXPORT float calc_TAS_from_EAS	(	float	speed_equivalent,
		float	pressure_ambient,
		float	temperature_celsius
	)

Calculate true airspeed (TAS) from equivalent airspeed (EAS).

Note that the true airspeed is NOT the groundspeed, because of the effects of wind

Parameters

speed_equivalent	current equivalent airspeed
pressure_ambient	pressure at the side of the tube/airplane
temperature_celsius	air temperature in degrees celcius

Returns: TAS in m/s

Definition at line 218 of file airspeed.cpp.

References CONSTANTS_AIR_DENSITY_SEA_LEVEL_15C, and get_air_density().

Referenced by Sensors::diff_pres_poll(), MavlinkReceiver::handle_message_hil_sensor(), and AirspeedValidator::update_EAS_TAS().

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◆ get_air_density()

__EXPORT float get_air_density	(	float	static_pressure,
		float	temperature_celsius
	)

Calculates air density.

Parameters

static_pressure	ambient pressure in millibar
temperature_celcius	air / ambient temperature in celcius

Definition at line 267 of file airspeed.cpp.

References CONSTANTS_ABSOLUTE_NULL_CELSIUS, and CONSTANTS_AIR_GAS_CONST.

Referenced by calc_EAS_from_TAS(), calc_IAS_corrected(), calc_TAS(), and calc_TAS_from_EAS().

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Enumerations

Functions

Enumeration Type Documentation

◆ AIRSPEED_COMPENSATION_MODEL

◆ AIRSPEED_SENSOR_MODEL

Function Documentation

◆ calc_EAS_from_IAS()

◆ calc_EAS_from_TAS()

◆ calc_IAS()

◆ calc_IAS_corrected()

◆ calc_TAS()

◆ calc_TAS_from_EAS()

◆ get_air_density()