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Air density is now calculated automatically from air pressure,

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temperature, and dewpoint.  The /environment/density-sea-level-slugft3
property has been removed, and the /environment/density-slugft3
property is read-only.
This commit is contained in:
david 2002-06-06 00:21:23 +00:00
parent 4acb59a020
commit 56642901b5
3 changed files with 127 additions and 80 deletions
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162
src/Environment/environment.cxx
View file

@ -44,11 +44,10 @@
FGEnvironment::FGEnvironment()
: _temperature_degc_table(new SGInterpTable),
_pressure_inhg_table(new SGInterpTable),
_density_slugft3_table(new SGInterpTable),
visibility_m(32000),
temperature_sea_level_degc(20),
temperature_sea_level_degc(15),
dewpoint_sea_level_degc(5), // guess
pressure_sea_level_inhg(29.92),
density_sea_level_slugft3(0.00237),
wind_from_heading_deg(0),
wind_speed_kt(0),
wind_from_north_fps(0),
@ -61,12 +60,11 @@ FGEnvironment::FGEnvironment()
FGEnvironment::FGEnvironment (const FGEnvironment &env)
: _temperature_degc_table(new SGInterpTable),
_pressure_inhg_table(new SGInterpTable),
_density_slugft3_table(new SGInterpTable),
elevation_ft(env.elevation_ft),
visibility_m(env.visibility_m),
temperature_sea_level_degc(env.temperature_sea_level_degc),
dewpoint_sea_level_degc(env.dewpoint_sea_level_degc),
pressure_sea_level_inhg(env.pressure_sea_level_inhg),
density_sea_level_slugft3(env.density_sea_level_slugft3),
wind_from_heading_deg(env.wind_from_heading_deg),
wind_speed_kt(env.wind_speed_kt),
wind_from_north_fps(env.wind_from_north_fps),
@ -80,7 +78,6 @@ FGEnvironment::~FGEnvironment()
{
delete _temperature_degc_table;
delete _pressure_inhg_table;
delete _density_slugft3_table;
}
@ -102,6 +99,18 @@ FGEnvironment::get_temperature_degc () const
return temperature_degc;
}
double
FGEnvironment::get_dewpoint_sea_level_degc () const
{
return dewpoint_sea_level_degc;
}
double
FGEnvironment::get_dewpoint_degc () const
{
return dewpoint_degc;
}
double
FGEnvironment::get_pressure_sea_level_inhg () const
{
@ -114,12 +123,6 @@ FGEnvironment::get_pressure_inhg () const
return pressure_inhg;
}
double
FGEnvironment::get_density_sea_level_slugft3 () const
{
return density_sea_level_slugft3;
}
double
FGEnvironment::get_density_slugft3 () const
{
@ -173,6 +176,7 @@ FGEnvironment::set_temperature_sea_level_degc (double t)
{
temperature_sea_level_degc = t;
_recalc_alt_temperature();
_recalc_density();
}
void
@ -180,6 +184,23 @@ FGEnvironment::set_temperature_degc (double t)
{
temperature_degc = t;
_recalc_sl_temperature();
_recalc_density();
}
void
FGEnvironment::set_dewpoint_sea_level_degc (double t)
{
dewpoint_sea_level_degc = t;
_recalc_alt_dewpoint();
_recalc_density();
}
void
FGEnvironment::set_dewpoint_degc (double t)
{
dewpoint_degc = t;
_recalc_sl_dewpoint();
_recalc_density();
}
void
@ -187,6 +208,7 @@ FGEnvironment::set_pressure_sea_level_inhg (double p)
{
pressure_sea_level_inhg = p;
_recalc_alt_pressure();
_recalc_density();
}
void
@ -194,20 +216,7 @@ FGEnvironment::set_pressure_inhg (double p)
{
pressure_inhg = p;
_recalc_sl_pressure();
}
void
FGEnvironment::set_density_sea_level_slugft3 (double d)
{
density_sea_level_slugft3 = d;
_recalc_alt_density();
}
void
FGEnvironment::set_density_slugft3 (double d)
{
density_slugft3 = d;
_recalc_sl_density();
_recalc_density();
}
void
@ -250,8 +259,9 @@ FGEnvironment::set_elevation_ft (double e)
{
elevation_ft = e;
_recalc_alt_temperature();
_recalc_alt_dewpoint();
_recalc_alt_pressure();
_recalc_alt_density();
_recalc_density();
}
// Atmosphere model.
@ -269,32 +279,31 @@ FGEnvironment::set_elevation_ft (double e)
// R=287. I chose to correct the temperature to 288.20, since 79F is
// pretty hot for a "standard" atmosphere.
// Elevation (ft), temperature factor (degK), pressure factor (inHG),
// density factor (slug/ft^3)
static double atmosphere_data[][4] = {
0.00, 1.00, 1.000, 1.000000,
2952.76, 0.98, 0.898, 0.916408,
5905.51, 0.96, 0.804, 0.838286,
8858.27, 0.94, 0.719, 0.765429,
11811.02, 0.92, 0.641, 0.697510,
14763.78, 0.90, 0.570, 0.634318,
17716.54, 0.88, 0.506, 0.575616,
20669.29, 0.86, 0.447, 0.521184,
23622.05, 0.84, 0.394, 0.470784,
26574.80, 0.82, 0.347, 0.424220,
29527.56, 0.80, 0.304, 0.381273,
32480.31, 0.78, 0.266, 0.341747,
35433.07, 0.76, 0.231, 0.305445,
38385.83, 0.75, 0.201, 0.266931,
41338.58, 0.75, 0.174, 0.231739,
44291.34, 0.75, 0.151, 0.201192,
47244.09, 0.75, 0.131, 0.174686,
50196.85, 0.75, 0.114, 0.151673,
53149.61, 0.75, 0.099, 0.131698,
56102.36, 0.75, 0.086, 0.114359,
59055.12, 0.75, 0.075, 0.099306,
62007.87, 0.75, 0.065, 0.086237,
-1, -1, -1, -1
// Elevation (ft), temperature factor (degK), pressure factor (inHG)
static double atmosphere_data[][3] = {
0.00, 1.00, 1.000,
2952.76, 0.98, 0.898,
5905.51, 0.96, 0.804,
8858.27, 0.94, 0.719,
11811.02, 0.92, 0.641,
14763.78, 0.90, 0.570,
17716.54, 0.88, 0.506,
20669.29, 0.86, 0.447,
23622.05, 0.84, 0.394,
26574.80, 0.82, 0.347,
29527.56, 0.80, 0.304,
32480.31, 0.78, 0.266,
35433.07, 0.76, 0.231,
38385.83, 0.75, 0.201,
41338.58, 0.75, 0.174,
44291.34, 0.75, 0.151,
47244.09, 0.75, 0.131,
50196.85, 0.75, 0.114,
53149.61, 0.75, 0.099,
56102.36, 0.75, 0.086,
59055.12, 0.75, 0.075,
62007.87, 0.75, 0.065,
-1, -1, -1
};
void
@ -305,8 +314,6 @@ FGEnvironment::_setup_tables ()
atmosphere_data[i][1]);
_pressure_inhg_table->addEntry(atmosphere_data[i][0],
atmosphere_data[i][2]);
_density_slugft3_table->addEntry(atmosphere_data[i][0],
atmosphere_data[i][3]);
}
}
@ -369,6 +376,28 @@ FGEnvironment::_recalc_alt_temperature ()
}
}
void
FGEnvironment::_recalc_sl_dewpoint ()
{
// 0.2degC/1000ft
// FIXME: this will work only for low
// elevations
dewpoint_sea_level_degc = dewpoint_degc + (elevation_ft * .0002);
if (dewpoint_sea_level_degc > temperature_sea_level_degc)
dewpoint_sea_level_degc = temperature_sea_level_degc;
}
void
FGEnvironment::_recalc_alt_dewpoint ()
{
// 0.2degC/1000ft
// FIXME: this will work only for low
// elevations
dewpoint_degc = dewpoint_sea_level_degc + (elevation_ft * .0002);
if (dewpoint_degc > temperature_degc)
dewpoint_degc = temperature_degc;
}
void
FGEnvironment::_recalc_sl_pressure ()
{
@ -384,18 +413,21 @@ FGEnvironment::_recalc_alt_pressure ()
}
void
FGEnvironment::_recalc_sl_density ()
FGEnvironment::_recalc_density ()
{
density_sea_level_slugft3 =
density_slugft3 / _density_slugft3_table->interpolate(elevation_ft);
}
double pressure_psf = pressure_inhg * 70.7487;
// adjust for humidity
// calculations taken from USA Today (oops!) at
// http://www.usatoday.com/weather/basics/density-calculations.htm
double temperature_degk = temperature_degc + 273.15;
double pressure_mb = pressure_inhg * 33.86;
double vapor_pressure_mb =
6.11 * pow(10.0, 7.5 * dewpoint_degc / (237.7 + dewpoint_degc));
double virtual_temperature_degk = temperature_degk / (1 - (vapor_pressure_mb / pressure_mb) * (1.0 - 0.622));
double virtual_temperature_degr = virtual_temperature_degk * 1.8;
void
FGEnvironment::_recalc_alt_density ()
{
density_slugft3 =
density_sea_level_slugft3 *
_density_slugft3_table->interpolate(elevation_ft);
density_slugft3 = pressure_psf / (virtual_temperature_degr * 1718);
}
// end of environment.cxx

16
src/Environment/environment.hxx
View file

@ -58,9 +58,10 @@ public:
virtual double get_temperature_sea_level_degc () const;
virtual double get_temperature_degc () const;
virtual double get_dewpoint_sea_level_degc () const;
virtual double get_dewpoint_degc () const;
virtual double get_pressure_sea_level_inhg () const;
virtual double get_pressure_inhg () const;
virtual double get_density_sea_level_slugft3 () const;
virtual double get_density_slugft3 () const;
virtual double get_wind_from_heading_deg () const;
@ -73,10 +74,10 @@ public:
virtual void set_temperature_sea_level_degc (double t);
virtual void set_temperature_degc (double t);
virtual void set_dewpoint_sea_level_degc (double d);
virtual void set_dewpoint_degc (double d);
virtual void set_pressure_sea_level_inhg (double p);
virtual void set_pressure_inhg (double p);
virtual void set_density_sea_level_slugft3 (double d);
virtual void set_density_slugft3 (double d);
virtual void set_wind_from_heading_deg (double h);
virtual void set_wind_speed_kt (double s);
@ -100,14 +101,14 @@ private:
void _recalc_sl_temperature ();
void _recalc_alt_temperature ();
void _recalc_sl_dewpoint ();
void _recalc_alt_dewpoint ();
void _recalc_sl_pressure ();
void _recalc_alt_pressure ();
void _recalc_sl_density ();
void _recalc_alt_density ();
void _recalc_density ();
SGInterpTable * _temperature_degc_table;
SGInterpTable * _pressure_inhg_table;
SGInterpTable * _density_slugft3_table;
double elevation_ft;
@ -116,9 +117,10 @@ private:
// Atmosphere
double temperature_sea_level_degc;
double temperature_degc;
double dewpoint_sea_level_degc;
double dewpoint_degc;
double pressure_sea_level_inhg;
double pressure_inhg;
double density_sea_level_slugft3;
double density_slugft3;
double wind_from_heading_deg;

29
src/Environment/environment_mgr.cxx
View file

@ -68,6 +68,14 @@ FGEnvironmentMgr::bind ()
&FGEnvironment::get_temperature_degc,
&FGEnvironment::set_temperature_degc);
fgSetArchivable("/environment/temperature-degc");
fgTie("/environment/dewpoint-sea-level-degc", _environment,
&FGEnvironment::get_dewpoint_sea_level_degc,
&FGEnvironment::set_dewpoint_sea_level_degc);
fgSetArchivable("/environment/dewpoint-sea-level-degc");
fgTie("/environment/dewpoint-degc", _environment,
&FGEnvironment::get_dewpoint_degc,
&FGEnvironment::set_dewpoint_degc);
fgSetArchivable("/environment/dewpoint-degc");
fgTie("/environment/pressure-sea-level-inhg", _environment,
&FGEnvironment::get_pressure_sea_level_inhg,
&FGEnvironment::set_pressure_sea_level_inhg);
@ -76,13 +84,8 @@ FGEnvironmentMgr::bind ()
&FGEnvironment::get_pressure_inhg,
&FGEnvironment::set_pressure_inhg);
fgSetArchivable("/environment/pressure-inhg");
fgTie("/environment/density-sea-level-slugft3", _environment,
&FGEnvironment::get_density_sea_level_slugft3,
&FGEnvironment::set_density_sea_level_slugft3);
fgSetArchivable("/environment/density-sea-level-slugft3");
fgTie("/environment/density-slugft3", _environment,
&FGEnvironment::get_density_slugft3,
&FGEnvironment::set_density_slugft3);
&FGEnvironment::get_density_slugft3); // read-only
fgSetArchivable("/environment/density-inhg");
fgTie("/environment/wind-from-heading-deg", _environment,
&FGEnvironment::get_wind_from_heading_deg,
@ -108,22 +111,27 @@ FGEnvironmentMgr::bind ()
fgTie(buf, this, i,
&FGEnvironmentMgr::get_cloud_layer_span_m,
&FGEnvironmentMgr::set_cloud_layer_span_m);
fgSetArchivable(buf);
sprintf(buf, "/environment/clouds/layer[%d]/elevation-ft", i);
fgTie(buf, this, i,
&FGEnvironmentMgr::get_cloud_layer_elevation_ft,
&FGEnvironmentMgr::set_cloud_layer_elevation_ft);
fgSetArchivable(buf);
sprintf(buf, "/environment/clouds/layer[%d]/thickness-ft", i);
fgTie(buf, this, i,
&FGEnvironmentMgr::get_cloud_layer_thickness_ft,
&FGEnvironmentMgr::set_cloud_layer_thickness_ft);
fgSetArchivable(buf);
sprintf(buf, "/environment/clouds/layer[%d]/transition-ft", i);
fgTie(buf, this, i,
&FGEnvironmentMgr::get_cloud_layer_transition_ft,
&FGEnvironmentMgr::set_cloud_layer_transition_ft);
fgSetArchivable(buf);
sprintf(buf, "/environment/clouds/layer[%d]/type", i);
fgTie(buf, this, i,
&FGEnvironmentMgr::get_cloud_layer_type,
&FGEnvironmentMgr::set_cloud_layer_type);
fgSetArchivable(buf);
}
}
@ -131,8 +139,13 @@ void
FGEnvironmentMgr::unbind ()
{
fgUntie("/environment/visibility-m");
fgUntie("/environment/wind-from-heading-deg");
fgUntie("/environment/wind-speed-kt");
fgUntie("/environment/temperature-sea-level-degc");
fgUntie("/environment/temperature-degc");
fgUntie("/environment/dewpoint-sea-level-degc");
fgUntie("/environment/dewpoint-degc");
fgUntie("/environment/pressure-sea-level-inhg");
fgUntie("/environment/pressure-inhg");
fgUntie("/environment/density-inhg");
fgUntie("/environment/wind-from-north-fps");
fgUntie("/environment/wind-from-east-fps");
fgUntie("/environment/wind-from-down-fps");