242 lines
7.1 KiB
C++
242 lines
7.1 KiB
C++
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
|
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
|
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
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"
|
|
|
|
static const char *IdSrc = "$Id$";
|
|
static const char *IdHdr = ID_ATMOSPHERE;
|
|
|
|
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
CLASS IMPLEMENTATION
|
|
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
|
|
|
|
|
|
FGAtmosphere::FGAtmosphere(FGFDMExec* fdmex) : FGModel(fdmex),
|
|
vWindNED(3)
|
|
{
|
|
Name = "FGAtmosphere";
|
|
lastIndex=0;
|
|
h = 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.
|
|
|
|
if (debug_lvl & 2) cout << "Instantiated: " << Name << endl;
|
|
}
|
|
|
|
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
|
FGAtmosphere::~FGAtmosphere()
|
|
{
|
|
if (debug_lvl & 2) cout << "Destroyed: FGAtmosphere" << endl;
|
|
}
|
|
|
|
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
|
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 (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);
|
|
|
|
} else { // skip Run() execution this time
|
|
}
|
|
return false;
|
|
}
|
|
|
|
//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
|
|
void FGAtmosphere::Calculate(float altitude)
|
|
{
|
|
//see reference [1]
|
|
|
|
float slope,reftemp,refpress;
|
|
int i=0; bool lookup = false;
|
|
// cout << "Atmosphere: h=" << altitude << " rho= " << density << endl;
|
|
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 0: // sea level
|
|
slope = -0.00356616; // R/ft.
|
|
reftemp = 518.67; // R
|
|
refpress = 2116.22; // psf
|
|
//refdens = 0.00237767; // slugs/cubic ft.
|
|
break;
|
|
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;
|
|
}
|
|
|
|
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::Debug(void)
|
|
{
|
|
//TODO: Add your source code here
|
|
}
|
|
|