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flightgear/src/FDM/JSBSim/FGAtmosphere.cpp

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/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Module: FGAtmosphere.cpp
Author: Jon Berndt
Implementation of 1959 Standard Atmosphere added by Tony Peden
Date started: 11/24/98
Purpose: Models the atmosphere
Called by: FGSimExec
------------- Copyright (C) 1999 Jon S. Berndt (jsb@hal-pc.org) -------------
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU 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 General Public License for more
details.
You should have received a copy of the GNU 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 General Public License can also be found on
the world wide web at http://www.gnu.org.
FUNCTIONAL DESCRIPTION
--------------------------------------------------------------------------------
Models the atmosphere. The equation used below was determined by a third order
curve fit using Excel. The data is from the ICAO atmosphere model.
HISTORY
--------------------------------------------------------------------------------
11/24/98 JSB Created
07/23/99 TP Added implementation of 1959 Standard Atmosphere
Moved calculation of Mach number to FGTranslation
Later updated to '76 model
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
COMMENTS, REFERENCES, and NOTES
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
[1] Anderson, John D. "Introduction to Flight, Third Edition", McGraw-Hill,
1989, ISBN 0-07-001641-0
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
INCLUDES
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
#include "FGAtmosphere.h"
#include "FGState.h"
#include "FGFDMExec.h"
#include "FGFCS.h"
#include "FGAircraft.h"
#include "FGTranslation.h"
#include "FGRotation.h"
#include "FGPosition.h"
#include "FGAuxiliary.h"
#include "FGOutput.h"
#include "FGMatrix33.h"
#include "FGColumnVector3.h"
#include "FGColumnVector4.h"
#include "FGPropertyManager.h"
static const char *IdSrc = "$Id$";
static const char *IdHdr = ID_ATMOSPHERE;
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CLASS IMPLEMENTATION
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
FGAtmosphere::FGAtmosphere(FGFDMExec* fdmex) : FGModel(fdmex)
{
Name = "FGAtmosphere";
lastIndex = 0;
h = 0.0;
psiw = 0.0;
htab[0]=0;
htab[1]=36089.239;
htab[2]=65616.798;
htab[3]=104986.878;
htab[4]=154199.475;
htab[5]=170603.675;
htab[6]=200131.234;
htab[7]=259186.352; //ft.
MagnitudedAccelDt = MagnitudeAccel = Magnitude = 0.0;
turbType = ttNone;
// turbType = ttBerndt; // temporarily disable turbulence until fully tested
TurbGain = 100.0;
bind();
Debug(0);
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
FGAtmosphere::~FGAtmosphere()
{
unbind();
Debug(1);
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
bool FGAtmosphere::InitModel(void)
{
FGModel::InitModel();
Calculate(h);
SLtemperature = temperature;
SLpressure = pressure;
SLdensity = density;
SLsoundspeed = sqrt(SHRatio*Reng*temperature);
rSLtemperature = 1.0/temperature;
rSLpressure = 1.0/pressure;
rSLdensity = 1.0/density;
rSLsoundspeed = 1.0/SLsoundspeed;
useExternal=false;
return true;
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
bool FGAtmosphere::Run(void)
{
if (!FGModel::Run()) { // if false then execute this Run()
//do temp, pressure, and density first
if (!useExternal) {
h = Position->Geth();
Calculate(h);
} else {
density = exDensity;
pressure = exPressure;
temperature = exTemperature;
}
if (turbType != ttNone) {
Turbulence();
vWindNED += vTurbulence;
}
if (vWindNED(1) != 0.0) psiw = atan2( vWindNED(2), vWindNED(1) );
if (psiw < 0) psiw += 2*M_PI;
soundspeed = sqrt(SHRatio*Reng*temperature);
State->Seta(soundspeed);
Debug(2);
} else { // skip Run() execution this time
}
return false;
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
//
// See reference 1
void FGAtmosphere::Calculate(double altitude)
{
double slope, reftemp, refpress;
int i = 0;
i = lastIndex;
if (altitude < htab[lastIndex]) {
if (altitude <= 0) {
i = 0;
altitude=0;
} else {
i = lastIndex-1;
while (htab[i] > altitude) i--;
}
} else if (altitude > htab[lastIndex+1]) {
if (altitude >= htab[7]) {
i = 7;
altitude = htab[7];
} else {
i = lastIndex+1;
while (htab[i+1] < altitude) i++;
}
}
switch(i) {
case 1: // 36089 ft.
slope = 0;
reftemp = 389.97;
refpress = 472.452;
//refdens = 0.000706032;
break;
case 2: // 65616 ft.
slope = 0.00054864;
reftemp = 389.97;
refpress = 114.636;
//refdens = 0.000171306;
break;
case 3: // 104986 ft.
slope = 0.00153619;
reftemp = 411.57;
refpress = 8.36364;
//refdens = 1.18422e-05;
break;
case 4: // 154199 ft.
slope = 0;
reftemp = 487.17;
refpress = 0.334882;
//refdens = 4.00585e-7;
break;
case 5: // 170603 ft.
slope = -0.00109728;
reftemp = 487.17;
refpress = 0.683084;
//refdens = 8.17102e-7;
break;
case 6: // 200131 ft.
slope = -0.00219456;
reftemp = 454.17;
refpress = 0.00684986;
//refdens = 8.77702e-9;
break;
case 7: // 259186 ft.
slope = 0;
reftemp = 325.17;
refpress = 0.000122276;
//refdens = 2.19541e-10;
break;
case 0:
default: // sea level
slope = -0.00356616; // R/ft.
reftemp = 518.67; // R
refpress = 2116.22; // psf
//refdens = 0.00237767; // slugs/cubic ft.
break;
}
if (slope == 0) {
temperature = reftemp;
pressure = refpress*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
//density = refdens*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
density = pressure/(Reng*temperature);
} else {
temperature = reftemp+slope*(altitude-htab[i]);
pressure = refpress*pow(temperature/reftemp,-Inertial->SLgravity()/(slope*Reng));
//density = refdens*pow(temperature/reftemp,-(Inertial->SLgravity()/(slope*Reng)+1));
density = pressure/(Reng*temperature);
}
lastIndex=i;
//cout << "Atmosphere: h=" << altitude << " rho= " << density << endl;
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
void FGAtmosphere::Turbulence(void)
{
switch (turbType) {
case ttBerndt:
vDirectiondAccelDt(eX) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
vDirectiondAccelDt(eY) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
vDirectiondAccelDt(eZ) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
MagnitudedAccelDt = 1 - 2.0*(((double)(rand()))/RAND_MAX);
MagnitudeAccel += MagnitudedAccelDt*rate*State->Getdt();
Magnitude += MagnitudeAccel*rate*State->Getdt();
vDirectiondAccelDt.Normalize();
vDirectionAccel += vDirectiondAccelDt*rate*State->Getdt();
vDirectionAccel.Normalize();
vDirection += vDirectionAccel*rate*State->Getdt();
vDirection.Normalize();
vTurbulence = TurbGain*Magnitude * vDirection;
vTurbulenceGrad = TurbGain*MagnitudeAccel * vDirection;
vBodyTurbGrad = State->GetTl2b()*vTurbulenceGrad;
vTurbPQR(eP) = vBodyTurbGrad(eY)/Aircraft->GetWingSpan();
if (Aircraft->GetHTailArm() != 0.0)
vTurbPQR(eQ) = vBodyTurbGrad(eZ)/Aircraft->GetHTailArm();
else
vTurbPQR(eQ) = vBodyTurbGrad(eZ)/10.0;
if (Aircraft->GetVTailArm())
vTurbPQR(eR) = vBodyTurbGrad(eX)/Aircraft->GetVTailArm();
else
vTurbPQR(eR) = vBodyTurbGrad(eX)/10.0;
break;
default:
break;
}
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
void FGAtmosphere::bind(void)
{
typedef double (FGAtmosphere::*PMF)(int) const;
PropertyManager->Tie("atmosphere/T-R", this,
&FGAtmosphere::GetTemperature);
PropertyManager->Tie("atmosphere/rho-slugs_ft3", this,
&FGAtmosphere::GetDensity);
PropertyManager->Tie("atmosphere/P-psf", this,
&FGAtmosphere::GetPressure);
PropertyManager->Tie("atmosphere/a-fps", this,
&FGAtmosphere::GetSoundSpeed);
PropertyManager->Tie("atmosphere/T-sl-R", this,
&FGAtmosphere::GetTemperatureSL);
PropertyManager->Tie("atmosphere/rho-sl-slugs_ft3", this,
&FGAtmosphere::GetDensitySL);
PropertyManager->Tie("atmosphere/P-sl-psf", this,
&FGAtmosphere::GetPressureSL);
PropertyManager->Tie("atmosphere/a-sl-fps", this,
&FGAtmosphere::GetSoundSpeedSL);
PropertyManager->Tie("atmosphere/theta-norm", this,
&FGAtmosphere::GetTemperatureRatio);
PropertyManager->Tie("atmosphere/sigma-norm", this,
&FGAtmosphere::GetDensityRatio);
PropertyManager->Tie("atmosphere/delta-norm", this,
&FGAtmosphere::GetPressureRatio);
PropertyManager->Tie("atmosphere/a-norm", this,
&FGAtmosphere::GetSoundSpeedRatio);
PropertyManager->Tie("atmosphere/psiw-rad", this,
&FGAtmosphere::GetWindPsi);
PropertyManager->Tie("atmosphere/p-turb-rad_sec", this,1,
(PMF)&FGAtmosphere::GetTurbPQR);
PropertyManager->Tie("atmosphere/q-turb-rad_sec", this,2,
(PMF)&FGAtmosphere::GetTurbPQR);
PropertyManager->Tie("atmosphere/r-turb-rad_sec", this,3,
(PMF)&FGAtmosphere::GetTurbPQR);
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
void FGAtmosphere::unbind(void)
{
PropertyManager->Untie("atmosphere/T-R");
PropertyManager->Untie("atmosphere/rho-slugs_ft3");
PropertyManager->Untie("atmosphere/P-psf");
PropertyManager->Untie("atmosphere/a-fps");
PropertyManager->Untie("atmosphere/T-sl-R");
PropertyManager->Untie("atmosphere/rho-sl-slugs_ft3");
PropertyManager->Untie("atmosphere/P-sl-psf");
PropertyManager->Untie("atmosphere/a-sl-fps");
PropertyManager->Untie("atmosphere/theta-norm");
PropertyManager->Untie("atmosphere/sigma-norm");
PropertyManager->Untie("atmosphere/delta-norm");
PropertyManager->Untie("atmosphere/a-norm");
PropertyManager->Untie("atmosphere/psiw-rad");
PropertyManager->Untie("atmosphere/p-turb-rad_sec");
PropertyManager->Untie("atmosphere/q-turb-rad_sec");
PropertyManager->Untie("atmosphere/r-turb-rad_sec");
}
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
// The bitmasked value choices are as follows:
// unset: In this case (the default) JSBSim would only print
// out the normally expected messages, essentially echoing
// the config files as they are read. If the environment
// variable is not set, debug_lvl is set to 1 internally
// 0: This requests JSBSim not to output any messages
// whatsoever.
// 1: This value explicity requests the normal JSBSim
// startup messages
// 2: This value asks for a message to be printed out when
// a class is instantiated
// 4: When this value is set, a message is displayed when a
// FGModel object executes its Run() method
// 8: When this value is set, various runtime state variables
// are printed out periodically
// 16: When set various parameters are sanity checked and
// a message is printed out when they go out of bounds
void FGAtmosphere::Debug(int from)
{
if (debug_lvl <= 0) return;
if (debug_lvl & 1) { // Standard console startup message output
if (from == 0) { // Constructor
}
}
if (debug_lvl & 2 ) { // Instantiation/Destruction notification
if (from == 0) cout << "Instantiated: FGAtmosphere" << endl;
if (from == 1) cout << "Destroyed: FGAtmosphere" << endl;
}
if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
}
if (debug_lvl & 8 ) { // Runtime state variables
}
if (debug_lvl & 16) { // Sanity checking
}
if (debug_lvl & 32) { // Turbulence
if (frame == 0 && from == 2) {
cout << "vTurbulence(X), vTurbulence(Y), vTurbulence(Z), "
<< "vTurbulenceGrad(X), vTurbulenceGrad(Y), vTurbulenceGrad(Z), "
<< "vDirection(X), vDirection(Y), vDirection(Z), "
<< "Magnitude, "
<< "vTurbPQR(P), vTurbPQR(Q), vTurbPQR(R), " << endl;
} else if (from == 2) {
cout << vTurbulence << ", " << vTurbulenceGrad << ", " << vDirection << ", " << Magnitude << ", " << vTurbPQR << endl;
}
}
if (debug_lvl & 64) {
if (from == 0) { // Constructor
cout << IdSrc << endl;
cout << IdHdr << endl;
}
}
}
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