/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Header: FGStandardAtmosphere.h Author: Jon Berndt Date started: 5/2011 ------------- Copyright (C) 2011 Jon S. Berndt (jon@jsbsim.org) ------------- This program is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. Further information about the GNU Lesser General Public License can also be found on the world wide web at http://www.gnu.org. HISTORY -------------------------------------------------------------------------------- 5/2011 JSB Created %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% SENTRY %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/ #ifndef FGSTANDARDATMOSPHERE_H #define FGSTANDARDATMOSPHERE_H /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% INCLUDES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/ #include #include "math/FGTable.h" #include "models/FGAtmosphere.h" /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% DEFINITIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/ #define ID_STANDARDATMOSPHERE "$Id: FGStandardAtmosphere.h,v 1.17 2012/04/13 13:18:27 jberndt Exp $" /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% FORWARD DECLARATIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/ namespace JSBSim { /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% CLASS DOCUMENTATION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/ /** Models the 1976 U.S. Standard Atmosphere, with the ability to modify the temperature and pressure. A base feature of the model is the temperature profile that is stored as an FGTable object with this data: @code GeoMet Alt Temp GeoPot Alt GeoMet Alt (ft) (deg R) (km) (km) --------- -------- ---------- ---------- 0.0 518.67 // 0.000 0.000 36151.6 390.0 // 11.000 11.019 65823.5 390.0 // 20.000 20.063 105518.4 411.6 // 32.000 32.162 155347.8 487.2 // 47.000 47.350 168677.8 487.2 // 51.000 51.413 235570.9 386.4 // 71.000 71.802 282152.2 336.5; // 84.852 86.000 @endcode The pressure is calculated at lower altitudes through the use of two equations that are presented in the U.S. Standard Atmosphere document (see references). Density, kinematic viscosity, speed of sound, etc., are all calculated based on various constants and temperature and pressure. At higher altitudes (above 86 km (282152 ft) a different and more complicated method of calculating pressure is used. The temperature may be modified through the use of several methods. Ultimately, these access methods allow the user to modify the sea level standard temperature, and/or the sea level standard pressure, so that the entire profile will be consistently and accurately calculated.

Properties

@property atmosphere/delta-T @property atmosphere/T-sl-dev-F @author Jon Berndt @see "U.S. Standard Atmosphere, 1976", NASA TM-X-74335 @version $Id: FGStandardAtmosphere.h,v 1.17 2012/04/13 13:18:27 jberndt Exp $ */ /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% CLASS DECLARATION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/ class FGStandardAtmosphere : public FGAtmosphere { public: /// Constructor FGStandardAtmosphere(FGFDMExec*); /// Destructor virtual ~FGStandardAtmosphere(); bool InitModel(void); // ************************************************************************* /// @name Temperature access functions. /// There are several ways to get the temperature, and several modeled temperature /// values that can be retrieved. The U.S. Standard Atmosphere temperature either /// at a specified altitude, or at sea level can be retrieved. These two temperatures /// do NOT include the effects of any bias or delta gradient that may have been /// supplied by the user. The modeled temperature and the modeled temperature /// at sea level can also be retrieved. These two temperatures DO include the /// effects of an optionally user-supplied bias or delta gradient. // @{ /// Returns the actual modeled temperature in degrees Rankine at a specified altitude. /// @param altitude The altitude above sea level (ASL) in feet. /// @return Modeled temperature in degrees Rankine at the specified altitude. virtual double GetTemperature(double altitude) const; /// Returns the standard temperature in degrees Rankine at a specified altitude. /// @param altitude The altitude in feet above sea level (ASL) to get the temperature at. /// @return The STANDARD temperature in degrees Rankine at the specified altitude. virtual double GetStdTemperature(double altitude) const; /// Returns the standard sea level temperature in degrees Rankine. /// @return The STANDARD temperature at sea level in degrees Rankine. virtual double GetStdTemperatureSL() const { return GetStdTemperature(0.0); } /// Returns the ratio of the standard temperature at the supplied altitude /// over the standard sea level temperature. virtual double GetStdTemperatureRatio(double h) const { return GetStdTemperature(h)*rSLtemperature; } /// Returns the temperature bias over the sea level value in degrees Rankine. virtual double GetTemperatureBias(eTemperature to) const { if (to == eCelsius || to == eKelvin) return TemperatureBias/1.80; else return TemperatureBias; } /// Returns the temperature gradient to be applied on top of the standard /// temperature gradient. virtual double GetTemperatureDeltaGradient(eTemperature to) { if (to == eCelsius || to == eKelvin) return TemperatureDeltaGradient/1.80; else return TemperatureDeltaGradient; } /// Sets the Sea Level temperature, if it is to be different than the standard. /// This function will calculate a bias - a difference - from the standard /// atmosphere temperature and will apply that bias to the entire /// temperature profile. This is one way to set the temperature bias. Using /// the SetTemperatureBias function will replace the value calculated by /// this function. /// @param t the temperature value in the unit provided. /// @param unit the unit of the temperature. virtual void SetTemperatureSL(double t, eTemperature unit=eFahrenheit); /// Sets the temperature at the supplied altitude, if it is to be different /// than the standard temperature. /// This function will calculate a bias - a difference - from the standard /// atmosphere temperature at the supplied altitude and will apply that /// calculated bias to the entire temperature profile. If a graded delta is /// present, that will be included in the calculation - that is, regardless /// of any graded delta present, a temperature bias will be determined so that /// the temperature requested in this function call will be reached. /// @param t The temperature value in the unit provided. /// @param h The altitude in feet above sea level. /// @param unit The unit of the temperature. virtual void SetTemperature(double t, double h, eTemperature unit=eFahrenheit); /// Sets the temperature bias to be added to the standard temperature at all altitudes. /// This function sets the bias - the difference - from the standard /// atmosphere temperature. This bias applies to the entire /// temperature profile. Another way to set the temperature bias is to use the /// SetSLTemperature function, which replaces the value calculated by /// this function with a calculated bias. /// @param t the temperature value in the unit provided. /// @param unit the unit of the temperature. virtual void SetTemperatureBias(eTemperature unit, double t); /// Sets a Sea Level temperature delta that is ramped out by 86 km. /// The value of the delta is used to calculate a delta gradient that is /// applied to the temperature at all altitudes below 86 km (282152 ft). /// For instance, if a temperature of 20 degrees F is supplied, the delta /// gradient would be 20/282152 - or, about 7.09E-5 degrees/ft. At sea level, /// the full 20 degrees would be added to the standard temperature, /// but that 20 degree delta would be reduced by 7.09E-5 degrees for every /// foot of altitude above sea level, so that by 86 km, there would be no /// further delta added to the standard temperature. /// The graded delta can be used along with the a bias to tailor the /// temperature profile as desired. /// @param t the sea level temperature delta value in the unit provided. /// @param unit the unit of the temperature. virtual void SetSLTemperatureGradedDelta(eTemperature unit, double t); /// Sets the temperature delta value at the supplied altitude/elevation above /// sea level, to be added to the standard temperature and ramped out by /// 86 km. /// This function computes the sea level delta from the standard atmosphere /// temperature at sea level. /// @param t the temperature skew value in the unit provided. /// @param unit the unit of the temperature. virtual void SetTemperatureGradedDelta(double t, double h, eTemperature unit=eFahrenheit); /// This function resets the model to apply no bias or delta gradient to the /// temperature. /// The delta gradient and bias values are reset to 0.0, and the standard /// temperature is used for the entire temperature profile at all altitudes. virtual void ResetSLTemperature(); //@} // ************************************************************************* /// @name Pressure access functions. //@{ /// Returns the pressure at a specified altitude in psf. virtual double GetPressure(double altitude) const; /// Returns the standard pressure at a specified altitude in psf virtual double GetStdPressure100K(double altitude) const; /// Returns the standard pressure at the specified altitude. virtual double GetStdPressure(double altitude) const; /** Sets the sea level pressure for modeling an off-standard pressure profile. This could be useful in the case where the pressure at an airfield is known or set for a particular simulation run. @param pressure The pressure in the units specified. @param unit the unit of measure that the specified pressure is supplied in.*/ virtual void SetPressureSL(ePressure unit, double pressure); /** Resets the sea level to the Standard sea level pressure, and recalculates dependent parameters so that the pressure calculations are standard. */ virtual void ResetSLPressure(); //@} // ************************************************************************* /// @name Density access functions. //@{ /// Returns the standard density at a specified altitude virtual double GetStdDensity(double altitude) const; //@} /// Prints the U.S. Standard Atmosphere table. virtual void PrintStandardAtmosphereTable(); protected: double StdSLtemperature, StdSLdensity, StdSLpressure, StdSLsoundspeed; // Standard sea level conditions double TemperatureBias; double TemperatureDeltaGradient; double GradientFadeoutAltitude; FGTable* StdAtmosTemperatureTable; std::vector LapseRateVector; std::vector PressureBreakpointVector; /// Recalculate the lapse rate vectors when the temperature profile is altered /// in a way that would change the lapse rates, such as when a gradient is applied. /// This function is also called to initialize the lapse rate vector. void CalculateLapseRates(); /// Calculate (or recalculate) the atmospheric pressure breakpoints at the /// altitudes in the standard temperature table. void CalculatePressureBreakpoints(); virtual void bind(void); void Debug(int from); }; } // namespace JSBSim //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% #endif