src/FDM/JSBSim/FGAtmosphere.cpp

   1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2
   3  Module:       FGAtmosphere.cpp
   4  Author:       Jon Berndt
   5                Implementation of 1959 Standard Atmosphere added by Tony Peden
   6  Date started: 11/24/98
   7  Purpose:      Models the atmosphere
   8  Called by:    FGSimExec
   9
  10  ------------- Copyright (C) 1999  Jon S. Berndt (jsb@hal-pc.org) -------------
  11
  12  This program is free software; you can redistribute it and/or modify it under
  13  the terms of the GNU General Public License as published by the Free Software
  14  Foundation; either version 2 of the License, or (at your option) any later
  15  version.
  16
  17  This program is distributed in the hope that it will be useful, but WITHOUT
  18  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  19  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  20  details.
  21
  22  You should have received a copy of the GNU General Public License along with
  23  this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  24  Place - Suite 330, Boston, MA  02111-1307, USA.
  25
  26  Further information about the GNU General Public License can also be found on
  27  the world wide web at http://www.gnu.org.
  28
  29 FUNCTIONAL DESCRIPTION
  30 --------------------------------------------------------------------------------
  31 Models the atmosphere. The equation used below was determined by a third order
  32 curve fit using Excel. The data is from the ICAO atmosphere model.
  33
  34 HISTORY
  35 --------------------------------------------------------------------------------
  36 11/24/98   JSB   Created
  37 07/23/99   TP    Added implementation of 1959 Standard Atmosphere
  38                  Moved calculation of Mach number to FGTranslation
  39 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  40 COMMENTS, REFERENCES,  and NOTES
  41 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  42 [1]   Anderson, John D. "Introduction to Flight, Third Edition", McGraw-Hill,
  43       1989, ISBN 0-07-001641-0
  44
  45 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  46 INCLUDES
  47 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  48
  49 #include "FGAtmosphere.h"
  50 #include "FGState.h"
  51 #include "FGFDMExec.h"
  52 #include "FGFCS.h"
  53 #include "FGAircraft.h"
  54 #include "FGTranslation.h"
  55 #include "FGRotation.h"
  56 #include "FGPosition.h"
  57 #include "FGAuxiliary.h"
  58 #include "FGOutput.h"
  59 #include "FGMatrix33.h"
  60 #include "FGColumnVector3.h"
  61 #include "FGColumnVector4.h"
  62 #include "FGPropertyManager.h"
  63
  64 static const char *IdSrc = "$Id$";
  65 static const char *IdHdr = ID_ATMOSPHERE;
  66
  67 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  68 CLASS IMPLEMENTATION
  69 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  70
  71
  72 FGAtmosphere::FGAtmosphere(FGFDMExec* fdmex) : FGModel(fdmex)
  73 {
  74   Name = "FGAtmosphere";
  75   lastIndex = 0;
  76   h = 0.0;
  77   psiw = 0.0;
  78   htab[0]=0;
  79   htab[1]=36089.239;
  80   htab[2]=65616.798;
  81   htab[3]=104986.878;
  82   htab[4]=154199.475;
  83   htab[5]=170603.675;
  84   htab[6]=200131.234;
  85   htab[7]=259186.352; //ft.
  86
  87   MagnitudedAccelDt = MagnitudeAccel = Magnitude = 0.0;
  88   turbType = ttNone;
  89 //  turbType = ttBerndt; // temporarily disable turbulence until fully tested
  90   TurbGain = 100.0;
  91
  92   bind();
  93   Debug(0);
  94 }
  95
  96 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  97
  98 FGAtmosphere::~FGAtmosphere()
  99 {
 100   unbind();
 101   Debug(1);
 102 }
 103
 104 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 105
 106 bool FGAtmosphere::InitModel(void)
 107 {
 108   FGModel::InitModel();
 109
 110   Calculate(h);
 111   SLtemperature = temperature;
 112   SLpressure    = pressure;
 113   SLdensity     = density;
 114   SLsoundspeed  = sqrt(SHRatio*Reng*temperature);
 115   rSLtemperature = 1.0/temperature;
 116   rSLpressure    = 1.0/pressure;
 117   rSLdensity     = 1.0/density;
 118   rSLsoundspeed  = 1.0/SLsoundspeed;
 119   useExternal=false;
 120
 121   return true;
 122 }
 123
 124 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 125
 126 bool FGAtmosphere::Run(void)
 127 {
 128   if (!FGModel::Run()) {                 // if false then execute this Run()
 129     //do temp, pressure, and density first
 130     if (!useExternal) {
 131       h = Position->Geth();
 132       Calculate(h);
 133     } else {
 134       density = exDensity;
 135       pressure = exPressure;
 136       temperature = exTemperature;
 137     }
 138
 139     if (turbType != ttNone) {
 140       Turbulence();
 141       vWindNED += vTurbulence;
 142     }
 143
 144     if (vWindNED(1) != 0.0) psiw = atan2( vWindNED(2), vWindNED(1) );
 145
 146     if (psiw < 0) psiw += 2*M_PI;
 147
 148     soundspeed = sqrt(SHRatio*Reng*temperature);
 149
 150     State->Seta(soundspeed);
 151
 152     Debug(2);
 153
 154   } else {                               // skip Run() execution this time
 155   }
 156
 157   return false;
 158 }
 159
 160 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 161 //
 162 // See reference 1
 163
 164 void FGAtmosphere::Calculate(double altitude)
 165 {
 166   double slope, reftemp, refpress;
 167   int i = 0;
 168
 169   i = lastIndex;
 170   if (altitude < htab[lastIndex]) {
 171     if (altitude <= 0) {
 172       i = 0;
 173       altitude=0;
 174     } else {
 175        i = lastIndex-1;
 176        while (htab[i] > altitude) i--;
 177     }
 178   } else if (altitude > htab[lastIndex+1]) {
 179     if (altitude >= htab[7]) {
 180       i = 7;
 181       altitude = htab[7];
 182     } else {
 183       i = lastIndex+1;
 184       while (htab[i+1] < altitude) i++;
 185     }
 186   }
 187
 188   switch(i) {
 189   case 1:     // 36089 ft.
 190     slope     = 0;
 191     reftemp   = 389.97;
 192     refpress  = 472.452;
 193     //refdens   = 0.000706032;
 194     break;
 195   case 2:     // 65616 ft.
 196     slope     = 0.00054864;
 197     reftemp   = 389.97;
 198     refpress  = 114.636;
 199     //refdens   = 0.000171306;
 200     break;
 201   case 3:     // 104986 ft.
 202     slope     = 0.00153619;
 203     reftemp   = 411.57;
 204     refpress  = 8.36364;
 205     //refdens   = 1.18422e-05;
 206     break;
 207   case 4:     // 154199 ft.
 208     slope     = 0;
 209     reftemp   = 487.17;
 210     refpress  = 0.334882;
 211     //refdens   = 4.00585e-7;
 212     break;
 213   case 5:     // 170603 ft.
 214     slope     = -0.00109728;
 215     reftemp   = 487.17;
 216     refpress  = 0.683084;
 217     //refdens   = 8.17102e-7;
 218     break;
 219   case 6:     // 200131 ft.
 220     slope     = -0.00219456;
 221     reftemp   = 454.17;
 222     refpress  = 0.00684986;
 223     //refdens   = 8.77702e-9;
 224     break;
 225   case 7:     // 259186 ft.
 226     slope     = 0;
 227     reftemp   = 325.17;
 228     refpress  = 0.000122276;
 229     //refdens   = 2.19541e-10;
 230     break;
 231   case 0:
 232   default:     // sea level
 233     slope     = -0.00356616; // R/ft.
 234     reftemp   = 518.67;    // R
 235     refpress  = 2116.22;    // psf
 236     //refdens   = 0.00237767;  // slugs/cubic ft.
 237     break;
 238
 239   }
 240
 241   if (slope == 0) {
 242     temperature = reftemp;
 243     pressure = refpress*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
 244     //density = refdens*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
 245     density = pressure/(Reng*temperature);
 246   } else {
 247     temperature = reftemp+slope*(altitude-htab[i]);
 248     pressure = refpress*pow(temperature/reftemp,-Inertial->SLgravity()/(slope*Reng));
 249     //density = refdens*pow(temperature/reftemp,-(Inertial->SLgravity()/(slope*Reng)+1));
 250     density = pressure/(Reng*temperature);
 251   }
 252   lastIndex=i;
 253   //cout << "Atmosphere:  h=" << altitude << " rho= " << density << endl;
 254 }
 255
 256 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 257
 258 void FGAtmosphere::Turbulence(void)
 259 {
 260   switch (turbType) {
 261   case ttBerndt:
 262     vDirectiondAccelDt(eX) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
 263     vDirectiondAccelDt(eY) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
 264     vDirectiondAccelDt(eZ) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
 265
 266     MagnitudedAccelDt = 1 - 2.0*(((double)(rand()))/RAND_MAX);
 267     MagnitudeAccel    += MagnitudedAccelDt*rate*State->Getdt();
 268     Magnitude         += MagnitudeAccel*rate*State->Getdt();
 269
 270     vDirectiondAccelDt.Normalize();
 271     vDirectionAccel += vDirectiondAccelDt*rate*State->Getdt();
 272     vDirectionAccel.Normalize();
 273     vDirection      += vDirectionAccel*rate*State->Getdt();
 274     vDirection.Normalize();
 275
 276     vTurbulence = TurbGain*Magnitude * vDirection;
 277     vTurbulenceGrad = TurbGain*MagnitudeAccel * vDirection;
 278
 279     vBodyTurbGrad = State->GetTl2b()*vTurbulenceGrad;
 280     vTurbPQR(eP) = vBodyTurbGrad(eY)/Aircraft->GetWingSpan();
 281     if (Aircraft->GetHTailArm() != 0.0)
 282       vTurbPQR(eQ) = vBodyTurbGrad(eZ)/Aircraft->GetHTailArm();
 283     else
 284       vTurbPQR(eQ) = vBodyTurbGrad(eZ)/10.0;
 285
 286     if (Aircraft->GetVTailArm())
 287       vTurbPQR(eR) = vBodyTurbGrad(eX)/Aircraft->GetVTailArm();
 288     else
 289       vTurbPQR(eR) = vBodyTurbGrad(eX)/10.0;
 290
 291     break;
 292   default:
 293     break;
 294   }
 295 }
 296
 297 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 298
 299 void FGAtmosphere::bind(void)
 300 {
 301   PropertyManager->Tie("atmosphere/T-R", this,
 302                        &FGAtmosphere::GetTemperature);
 303   PropertyManager->Tie("atmosphere/rho-slugs_ft3", this,
 304                        &FGAtmosphere::GetDensity);
 305   PropertyManager->Tie("atmosphere/P-psf", this,
 306                        &FGAtmosphere::GetPressure);
 307   PropertyManager->Tie("atmosphere/a-fps", this,
 308                        &FGAtmosphere::GetSoundSpeed);
 309   PropertyManager->Tie("atmosphere/T-sl-R", this,
 310                        &FGAtmosphere::GetTemperatureSL);
 311   PropertyManager->Tie("atmosphere/rho-sl-slugs_ft3", this,
 312                        &FGAtmosphere::GetDensitySL);
 313   PropertyManager->Tie("atmosphere/P-sl-psf", this,
 314                        &FGAtmosphere::GetPressureSL);
 315   PropertyManager->Tie("atmosphere/a-sl-fps", this,
 316                        &FGAtmosphere::GetSoundSpeedSL);
 317   PropertyManager->Tie("atmosphere/theta-norm", this,
 318                        &FGAtmosphere::GetTemperatureRatio);
 319   PropertyManager->Tie("atmosphere/sigma-norm", this,
 320                        &FGAtmosphere::GetDensityRatio);
 321   PropertyManager->Tie("atmosphere/delta-norm", this,
 322                        &FGAtmosphere::GetPressureRatio);
 323   PropertyManager->Tie("atmosphere/a-norm", this,
 324                        &FGAtmosphere::GetSoundSpeedRatio);
 325   PropertyManager->Tie("atmosphere/psiw-rad", this,
 326                        &FGAtmosphere::GetWindPsi);
 327   PropertyManager->Tie("atmosphere/p-turb-rad_sec", this,1,
 328                        &FGAtmosphere::GetTurbPQR);
 329   PropertyManager->Tie("atmosphere/q-turb-rad_sec", this,2,
 330                        &FGAtmosphere::GetTurbPQR);
 331   PropertyManager->Tie("atmosphere/r-turb-rad_sec", this,3,
 332                        &FGAtmosphere::GetTurbPQR);
 333 }
 334
 335 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 336
 337 void FGAtmosphere::unbind(void)
 338 {
 339   PropertyManager->Untie("atmosphere/T-R");
 340   PropertyManager->Untie("atmosphere/rho-slugs_ft3");
 341   PropertyManager->Untie("atmosphere/P-psf");
 342   PropertyManager->Untie("atmosphere/a-fps");
 343   PropertyManager->Untie("atmosphere/T-sl-R");
 344   PropertyManager->Untie("atmosphere/rho-sl-slugs_ft3");
 345   PropertyManager->Untie("atmosphere/P-sl-psf");
 346   PropertyManager->Untie("atmosphere/a-sl-fps");
 347   PropertyManager->Untie("atmosphere/theta-norm");
 348   PropertyManager->Untie("atmosphere/sigma-norm");
 349   PropertyManager->Untie("atmosphere/delta-norm");
 350   PropertyManager->Untie("atmosphere/a-norm");
 351   PropertyManager->Untie("atmosphere/psiw-rad");
 352   PropertyManager->Untie("atmosphere/p-turb-rad_sec");
 353   PropertyManager->Untie("atmosphere/q-turb-rad_sec");
 354   PropertyManager->Untie("atmosphere/r-turb-rad_sec");
 355 }
 356
 357 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 358 //    The bitmasked value choices are as follows:
 359 //    unset: In this case (the default) JSBSim would only print
 360 //       out the normally expected messages, essentially echoing
 361 //       the config files as they are read. If the environment
 362 //       variable is not set, debug_lvl is set to 1 internally
 363 //    0: This requests JSBSim not to output any messages
 364 //       whatsoever.
 365 //    1: This value explicity requests the normal JSBSim
 366 //       startup messages
 367 //    2: This value asks for a message to be printed out when
 368 //       a class is instantiated
 369 //    4: When this value is set, a message is displayed when a
 370 //       FGModel object executes its Run() method
 371 //    8: When this value is set, various runtime state variables
 372 //       are printed out periodically
 373 //    16: When set various parameters are sanity checked and
 374 //       a message is printed out when they go out of bounds
 375
 376 void FGAtmosphere::Debug(int from)
 377 {
 378   if (debug_lvl <= 0) return;
 379
 380   if (debug_lvl & 1) { // Standard console startup message output
 381     if (from == 0) { // Constructor
 382     }
 383   }
 384   if (debug_lvl & 2 ) { // Instantiation/Destruction notification
 385     if (from == 0) cout << "Instantiated: FGAtmosphere" << endl;
 386     if (from == 1) cout << "Destroyed:    FGAtmosphere" << endl;
 387   }
 388   if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
 389   }
 390   if (debug_lvl & 8 ) { // Runtime state variables
 391   }
 392   if (debug_lvl & 16) { // Sanity checking
 393   }
 394   if (debug_lvl & 32) { // Turbulence
 395     if (frame == 0 && from == 2) {
 396       cout << "vTurbulence(X), vTurbulence(Y), vTurbulence(Z), "
 397            << "vTurbulenceGrad(X), vTurbulenceGrad(Y), vTurbulenceGrad(Z), "
 398            << "vDirection(X), vDirection(Y), vDirection(Z), "
 399            << "Magnitude, "
 400            << "vTurbPQR(P), vTurbPQR(Q), vTurbPQR(R), " << endl;
 401     } else if (from == 2) {
 402       cout << vTurbulence << ", " << vTurbulenceGrad << ", " << vDirection << ", " << Magnitude << ", " << vTurbPQR << endl;
 403     }
 404   }
 405   if (debug_lvl & 64) {
 406     if (from == 0) { // Constructor
 407       cout << IdSrc << endl;
 408       cout << IdHdr << endl;
 409     }
 410   }
 411 }
 412