307 lines
8.9 KiB
C++
307 lines
8.9 KiB
C++
/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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Module: FGAtmosphere.cpp
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Author: Jon Berndt
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Implementation of 1959 Standard Atmosphere added by Tony Peden
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Date started: 11/24/98
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Purpose: Models the atmosphere
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Called by: FGSimExec
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------------- Copyright (C) 1999 Jon S. Berndt (jsb@hal-pc.org) -------------
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This program is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation; either version 2 of the License, or (at your option) any later
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version.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along with
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this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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Place - Suite 330, Boston, MA 02111-1307, USA.
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Further information about the GNU General Public License can also be found on
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the world wide web at http://www.gnu.org.
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FUNCTIONAL DESCRIPTION
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--------------------------------------------------------------------------------
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Models the atmosphere. The equation used below was determined by a third order
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curve fit using Excel. The data is from the ICAO atmosphere model.
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HISTORY
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--------------------------------------------------------------------------------
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11/24/98 JSB Created
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07/23/99 TP Added implementation of 1959 Standard Atmosphere
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Moved calculation of Mach number to FGTranslation
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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COMMENTS, REFERENCES, and NOTES
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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[1] Anderson, John D. "Introduction to Flight, Third Edition", McGraw-Hill,
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1989, ISBN 0-07-001641-0
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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INCLUDES
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
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#include "FGAtmosphere.h"
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#include "FGState.h"
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#include "FGFDMExec.h"
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#include "FGFCS.h"
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#include "FGAircraft.h"
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#include "FGTranslation.h"
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#include "FGRotation.h"
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#include "FGPosition.h"
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#include "FGAuxiliary.h"
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#include "FGOutput.h"
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#include "FGMatrix33.h"
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#include "FGColumnVector3.h"
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#include "FGColumnVector4.h"
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static const char *IdSrc = "$Id$";
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static const char *IdHdr = ID_ATMOSPHERE;
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/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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CLASS IMPLEMENTATION
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
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FGAtmosphere::FGAtmosphere(FGFDMExec* fdmex) : FGModel(fdmex)
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{
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Name = "FGAtmosphere";
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lastIndex=0;
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h = 0;
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htab[0]=0;
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htab[1]=36089.239;
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htab[2]=65616.798;
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htab[3]=104986.878;
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htab[4]=154199.475;
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htab[5]=170603.675;
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htab[6]=200131.234;
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htab[7]=259186.352; //ft.
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MagnitudedAccelDt = MagnitudeAccel = Magnitude = 0.0;
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turbType = ttNone;
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// turbType = ttBerndt; // temporarily disable turbulence until fully tested
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TurbGain = 100.0;
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if (debug_lvl & 2) cout << "Instantiated: " << Name << endl;
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}
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//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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FGAtmosphere::~FGAtmosphere()
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{
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if (debug_lvl & 2) cout << "Destroyed: FGAtmosphere" << endl;
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}
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//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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bool FGAtmosphere::InitModel(void)
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{
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FGModel::InitModel();
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Calculate(h);
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SLtemperature = temperature;
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SLpressure = pressure;
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SLdensity = density;
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SLsoundspeed = sqrt(SHRatio*Reng*temperature);
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rSLtemperature = 1.0/temperature;
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rSLpressure = 1.0/pressure;
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rSLdensity = 1.0/density;
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rSLsoundspeed = 1.0/SLsoundspeed;
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useExternal=false;
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return true;
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}
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//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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bool FGAtmosphere::Run(void)
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{
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if (!FGModel::Run()) { // if false then execute this Run()
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//do temp, pressure, and density first
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if (!useExternal) {
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h = Position->Geth();
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Calculate(h);
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} else {
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density = exDensity;
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pressure = exPressure;
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temperature = exTemperature;
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}
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if (turbType != ttNone) {
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Turbulence();
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vWindNED += vTurbulence;
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}
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if (vWindNED(1) != 0.0) psiw = atan2( vWindNED(2), vWindNED(1) );
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if (psiw < 0) psiw += 2*M_PI;
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soundspeed = sqrt(SHRatio*Reng*temperature);
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State->Seta(soundspeed);
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if (debug_lvl > 1) Debug();
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} else { // skip Run() execution this time
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}
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return false;
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}
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//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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//
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// See reference 1
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void FGAtmosphere::Calculate(double altitude)
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{
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double slope, reftemp, refpress;
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int i = 0;
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i = lastIndex;
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if (altitude < htab[lastIndex]) {
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if (altitude <= 0) {
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i = 0;
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altitude=0;
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} else {
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i = lastIndex-1;
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while (htab[i] > altitude) i--;
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}
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} else if (altitude > htab[lastIndex+1]){
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if (altitude >= htab[7]){
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i = 7;
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altitude = htab[7];
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} else {
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i = lastIndex+1;
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while(htab[i+1] < altitude) i++;
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}
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}
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switch(i) {
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case 1: // 36089 ft.
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slope = 0;
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reftemp = 389.97;
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refpress = 472.452;
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//refdens = 0.000706032;
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break;
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case 2: // 65616 ft.
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slope = 0.00054864;
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reftemp = 389.97;
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refpress = 114.636;
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//refdens = 0.000171306;
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break;
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case 3: // 104986 ft.
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slope = 0.00153619;
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reftemp = 411.57;
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refpress = 8.36364;
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//refdens = 1.18422e-05;
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break;
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case 4: // 154199 ft.
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slope = 0;
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reftemp = 487.17;
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refpress = 0.334882;
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//refdens = 4.00585e-7;
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break;
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case 5: // 170603 ft.
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slope = -0.00109728;
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reftemp = 487.17;
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refpress = 0.683084;
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//refdens = 8.17102e-7;
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break;
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case 6: // 200131 ft.
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slope = -0.00219456;
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reftemp = 454.17;
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refpress = 0.00684986;
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//refdens = 8.77702e-9;
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break;
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case 7: // 259186 ft.
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slope = 0;
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reftemp = 325.17;
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refpress = 0.000122276;
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//refdens = 2.19541e-10;
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break;
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case 0:
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default: // sea level
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slope = -0.00356616; // R/ft.
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reftemp = 518.67; // R
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refpress = 2116.22; // psf
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//refdens = 0.00237767; // slugs/cubic ft.
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break;
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}
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if (slope == 0) {
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temperature = reftemp;
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pressure = refpress*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
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//density = refdens*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
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density = pressure/(Reng*temperature);
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} else {
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temperature = reftemp+slope*(altitude-htab[i]);
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pressure = refpress*pow(temperature/reftemp,-Inertial->SLgravity()/(slope*Reng));
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//density = refdens*pow(temperature/reftemp,-(Inertial->SLgravity()/(slope*Reng)+1));
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density = pressure/(Reng*temperature);
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}
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lastIndex=i;
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//cout << "Atmosphere: h=" << altitude << " rho= " << density << endl;
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}
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//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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void FGAtmosphere::Turbulence(void)
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{
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switch (turbType) {
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case ttBerndt:
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vDirectiondAccelDt(eX) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
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vDirectiondAccelDt(eY) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
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vDirectiondAccelDt(eZ) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
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MagnitudedAccelDt = 1 - 2.0*(((double)(rand()))/RAND_MAX);
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MagnitudeAccel += MagnitudedAccelDt*rate*State->Getdt();
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Magnitude += MagnitudeAccel*rate*State->Getdt();
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vDirectiondAccelDt.Normalize();
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vDirectionAccel += vDirectiondAccelDt*rate*State->Getdt();
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vDirectionAccel.Normalize();
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vDirection += vDirectionAccel*rate*State->Getdt();
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vDirection.Normalize();
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vTurbulence = TurbGain*Magnitude * vDirection;
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vTurbulenceGrad = TurbGain*MagnitudeAccel * vDirection;
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vBodyTurbGrad = State->GetTl2b()*vTurbulenceGrad;
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vTurbPQR(eP) = vBodyTurbGrad(eY)/Aircraft->GetWingSpan();
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if (Aircraft->GetHTailArm() != 0.0)
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vTurbPQR(eQ) = vBodyTurbGrad(eZ)/Aircraft->GetHTailArm();
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else
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vTurbPQR(eQ) = vBodyTurbGrad(eZ)/10.0;
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if (Aircraft->GetVTailArm())
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vTurbPQR(eR) = vBodyTurbGrad(eX)/Aircraft->GetVTailArm();
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else
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vTurbPQR(eR) = vBodyTurbGrad(eX)/10.0;
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break;
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default:
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break;
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}
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}
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//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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void FGAtmosphere::Debug(void)
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{
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if (frame == 0) {
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cout << "vTurbulence(X), vTurbulence(Y), vTurbulence(Z), "
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<< "vTurbulenceGrad(X), vTurbulenceGrad(Y), vTurbulenceGrad(Z), "
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<< "vDirection(X), vDirection(Y), vDirection(Z), "
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<< "Magnitude, "
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<< "vTurbPQR(P), vTurbPQR(Q), vTurbPQR(R), " << endl;
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} else {
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cout << vTurbulence << ", " << vTurbulenceGrad << ", " << vDirection << ", " << Magnitude << ", " << vTurbPQR << endl;
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}
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}
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