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                  Later updated to '76 model
  40 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  41 COMMENTS, REFERENCES,  and NOTES
  42 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  43 [1]   Anderson, John D. "Introduction to Flight, Third Edition", McGraw-Hill,
  44       1989, ISBN 0-07-001641-0
  45
  46 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  47 INCLUDES
  48 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  49
  50 #include "FGAtmosphere.h"
  51 #include "FGState.h"
  52 #include "FGFDMExec.h"
  53 #include "FGFCS.h"
  54 #include "FGAircraft.h"
  55 #include "FGTranslation.h"
  56 #include "FGRotation.h"
  57 #include "FGPosition.h"
  58 #include "FGAuxiliary.h"
  59 #include "FGOutput.h"
  60 #include "FGMatrix33.h"
  61 #include "FGColumnVector3.h"
  62 #include "FGColumnVector4.h"
  63 #include "FGPropertyManager.h"
  64
  65 namespace JSBSim {
  66
  67 static const char *IdSrc = "$Id$";
  68 static const char *IdHdr = ID_ATMOSPHERE;
  69
  70 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  71 CLASS IMPLEMENTATION
  72 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  73
  74
  75 FGAtmosphere::FGAtmosphere(FGFDMExec* fdmex) : FGModel(fdmex)
  76 {
  77   Name = "FGAtmosphere";
  78   lastIndex = 0;
  79   h = 0.0;
  80   psiw = 0.0;
  81   htab[0]=0;
  82   htab[1]=36089.239;
  83   htab[2]=65616.798;
  84   htab[3]=104986.878;
  85   htab[4]=154199.475;
  86   htab[5]=170603.675;
  87   htab[6]=200131.234;
  88   htab[7]=259186.352; //ft.
  89
  90   MagnitudedAccelDt = MagnitudeAccel = Magnitude = 0.0;
  91 //   turbType = ttNone;
  92   turbType = ttStandard;
  93 //   turbType = ttBerndt;
  94   TurbGain = 0.0;
  95
  96   bind();
  97   Debug(0);
  98 }
  99
 100 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 101
 102 FGAtmosphere::~FGAtmosphere()
 103 {
 104   unbind();
 105   Debug(1);
 106 }
 107
 108 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 109
 110 bool FGAtmosphere::InitModel(void)
 111 {
 112   FGModel::InitModel();
 113
 114   Calculate(h);
 115   SLtemperature = intTemperature;
 116   SLpressure    = intPressure;
 117   SLdensity     = intDensity;
 118   SLsoundspeed  = sqrt(SHRatio*Reng*intTemperature);
 119   rSLtemperature = 1.0/intTemperature;
 120   rSLpressure    = 1.0/intPressure;
 121   rSLdensity     = 1.0/intDensity;
 122   rSLsoundspeed  = 1.0/SLsoundspeed;
 123   temperature=&intTemperature;
 124   pressure=&intPressure;
 125   density=&intDensity;
 126
 127   useExternal=false;
 128
 129   return true;
 130 }
 131
 132 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 133
 134 bool FGAtmosphere::Run(void)
 135 {
 136   if (!FGModel::Run()) {                 // if false then execute this Run()
 137     //do temp, pressure, and density first
 138     if (!useExternal) {
 139       h = Position->Geth();
 140       Calculate(h);
 141     }
 142
 143     if (turbType != ttNone) {
 144       Turbulence();
 145       vWindNED += vTurbulence;
 146     }
 147
 148     if (vWindNED(1) != 0.0) psiw = atan2( vWindNED(2), vWindNED(1) );
 149
 150     if (psiw < 0) psiw += 2*M_PI;
 151
 152     soundspeed = sqrt(SHRatio*Reng*(*temperature));
 153
 154     State->Seta(soundspeed);
 155
 156     Debug(2);
 157
 158         return false;
 159   } else {                               // skip Run() execution this time
 160         return true;
 161   }
 162 }
 163
 164 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 165 //
 166 // See reference 1
 167
 168 void FGAtmosphere::Calculate(double altitude)
 169 {
 170   double slope, reftemp, refpress;
 171   int i = 0;
 172
 173   i = lastIndex;
 174   if (altitude < htab[lastIndex]) {
 175     if (altitude <= 0) {
 176       i = 0;
 177       altitude=0;
 178     } else {
 179        i = lastIndex-1;
 180        while (htab[i] > altitude) i--;
 181     }
 182   } else if (altitude > htab[lastIndex+1]) {
 183     if (altitude >= htab[7]) {
 184       i = 7;
 185       altitude = htab[7];
 186     } else {
 187       i = lastIndex+1;
 188       while (htab[i+1] < altitude) i++;
 189     }
 190   }
 191
 192   switch(i) {
 193   case 1:     // 36089 ft.
 194     slope     = 0;
 195     reftemp   = 389.97;
 196     refpress  = 472.452;
 197     //refdens   = 0.000706032;
 198     break;
 199   case 2:     // 65616 ft.
 200     slope     = 0.00054864;
 201     reftemp   = 389.97;
 202     refpress  = 114.636;
 203     //refdens   = 0.000171306;
 204     break;
 205   case 3:     // 104986 ft.
 206     slope     = 0.00153619;
 207     reftemp   = 411.57;
 208     refpress  = 8.36364;
 209     //refdens   = 1.18422e-05;
 210     break;
 211   case 4:     // 154199 ft.
 212     slope     = 0;
 213     reftemp   = 487.17;
 214     refpress  = 0.334882;
 215     //refdens   = 4.00585e-7;
 216     break;
 217   case 5:     // 170603 ft.
 218     slope     = -0.00109728;
 219     reftemp   = 487.17;
 220     refpress  = 0.683084;
 221     //refdens   = 8.17102e-7;
 222     break;
 223   case 6:     // 200131 ft.
 224     slope     = -0.00219456;
 225     reftemp   = 454.17;
 226     refpress  = 0.00684986;
 227     //refdens   = 8.77702e-9;
 228     break;
 229   case 7:     // 259186 ft.
 230     slope     = 0;
 231     reftemp   = 325.17;
 232     refpress  = 0.000122276;
 233     //refdens   = 2.19541e-10;
 234     break;
 235   case 0:
 236   default:     // sea level
 237     slope     = -0.00356616; // R/ft.
 238     reftemp   = 518.67;    // R
 239     refpress  = 2116.22;    // psf
 240     //refdens   = 0.00237767;  // slugs/cubic ft.
 241     break;
 242
 243   }
 244
 245   if (slope == 0) {
 246     intTemperature = reftemp;
 247     intPressure = refpress*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
 248     //intDensity = refdens*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
 249     intDensity = intPressure/(Reng*intTemperature);
 250   } else {
 251     intTemperature = reftemp+slope*(altitude-htab[i]);
 252     intPressure = refpress*pow(intTemperature/reftemp,-Inertial->SLgravity()/(slope*Reng));
 253     //intDensity = refdens*pow(intTemperature/reftemp,-(Inertial->SLgravity()/(slope*Reng)+1));
 254     intDensity = intPressure/(Reng*intTemperature);
 255   }
 256   lastIndex=i;
 257   //cout << "Atmosphere:  h=" << altitude << " rho= " << intDensity << endl;
 258 }
 259
 260 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 261
 262 void FGAtmosphere::Turbulence(void)
 263 {
 264   switch (turbType) {
 265   case ttStandard: {
 266     vDirectiondAccelDt(eX) = 1 - 2.0*(double(rand())/double(RAND_MAX));
 267     vDirectiondAccelDt(eY) = 1 - 2.0*(double(rand())/double(RAND_MAX));
 268     vDirectiondAccelDt(eZ) = 1 - 2.0*(double(rand())/double(RAND_MAX));
 269
 270     MagnitudedAccelDt = 1 - 2.0*(double(rand())/double(RAND_MAX));
 271     MagnitudeAccel    += MagnitudedAccelDt*rate*State->Getdt();
 272     Magnitude         += MagnitudeAccel*rate*State->Getdt();
 273
 274     vDirectiondAccelDt.Normalize();
 275     vDirectionAccel += vDirectiondAccelDt*rate*State->Getdt();
 276     vDirectionAccel.Normalize();
 277     vDirection      += vDirectionAccel*rate*State->Getdt();
 278
 279     vDirection.Normalize();
 280
 281                                 // Diminish turbulence within three wingspans
 282                                 // of the ground
 283     vTurbulence = TurbGain*Magnitude * vDirection;
 284     double HOverBMAC = Position->GetHOverBMAC();
 285     if (HOverBMAC < 3.0)
 286         vTurbulence *= (HOverBMAC / 3.0) * (HOverBMAC / 3.0);
 287
 288     vTurbulenceGrad = TurbGain*MagnitudeAccel * vDirection;
 289
 290     vBodyTurbGrad = State->GetTl2b()*vTurbulenceGrad;
 291     vTurbPQR(eP) = vBodyTurbGrad(eY)/Aircraft->GetWingSpan();
 292 //     if (Aircraft->GetHTailArm() != 0.0)
 293 //       vTurbPQR(eQ) = vBodyTurbGrad(eZ)/Aircraft->GetHTailArm();
 294 //     else
 295 //       vTurbPQR(eQ) = vBodyTurbGrad(eZ)/10.0;
 296
 297     if (Aircraft->GetVTailArm())
 298       vTurbPQR(eR) = vBodyTurbGrad(eX)/Aircraft->GetVTailArm();
 299     else
 300       vTurbPQR(eR) = vBodyTurbGrad(eX)/10.0;
 301
 302                                 // Clear the horizontal forces
 303                                 // actually felt by the plane, now
 304                                 // that we've used them to calculate
 305                                 // moments.
 306     vTurbulence(eX) = 0.0;
 307     vTurbulence(eY) = 0.0;
 308
 309     break;
 310   }
 311   case ttBerndt: {
 312     vDirectiondAccelDt(eX) = 1 - 2.0*(double(rand())/double(RAND_MAX));
 313     vDirectiondAccelDt(eY) = 1 - 2.0*(double(rand())/double(RAND_MAX));
 314     vDirectiondAccelDt(eZ) = 1 - 2.0*(double(rand())/double(RAND_MAX));
 315
 316
 317     MagnitudedAccelDt = 1 - 2.0*(double(rand())/double(RAND_MAX)) - Magnitude;
 318     MagnitudeAccel    += MagnitudedAccelDt*rate*State->Getdt();
 319     Magnitude         += MagnitudeAccel*rate*State->Getdt();
 320
 321     vDirectiondAccelDt.Normalize();
 322     vDirectionAccel += vDirectiondAccelDt*rate*State->Getdt();
 323     vDirectionAccel.Normalize();
 324     vDirection      += vDirectionAccel*rate*State->Getdt();
 325
 326                                 // Diminish z-vector within two wingspans
 327                                 // of the ground
 328     double HOverBMAC = Position->GetHOverBMAC();
 329     if (HOverBMAC < 2.0)
 330         vDirection(eZ) *= HOverBMAC / 2.0;
 331
 332     vDirection.Normalize();
 333
 334     vTurbulence = TurbGain*Magnitude * vDirection;
 335     vTurbulenceGrad = TurbGain*MagnitudeAccel * vDirection;
 336
 337     vBodyTurbGrad = State->GetTl2b()*vTurbulenceGrad;
 338     vTurbPQR(eP) = vBodyTurbGrad(eY)/Aircraft->GetWingSpan();
 339     if (Aircraft->GetHTailArm() != 0.0)
 340       vTurbPQR(eQ) = vBodyTurbGrad(eZ)/Aircraft->GetHTailArm();
 341     else
 342       vTurbPQR(eQ) = vBodyTurbGrad(eZ)/10.0;
 343
 344     if (Aircraft->GetVTailArm())
 345       vTurbPQR(eR) = vBodyTurbGrad(eX)/Aircraft->GetVTailArm();
 346     else
 347       vTurbPQR(eR) = vBodyTurbGrad(eX)/10.0;
 348
 349     break;
 350   }
 351   default:
 352     break;
 353   }
 354 }
 355
 356 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 357
 358 void FGAtmosphere::UseExternal(void) {
 359   temperature=&exTemperature;
 360   pressure=&exPressure;
 361   density=&exDensity;
 362   useExternal=true;
 363 }
 364
 365 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 366
 367 void FGAtmosphere::UseInternal(void) {
 368   temperature=&intTemperature;
 369   pressure=&intPressure;
 370   density=&intDensity;
 371   useExternal=false;
 372 }
 373
 374
 375 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 376
 377 void FGAtmosphere::bind(void)
 378 {
 379   typedef double (FGAtmosphere::*PMF)(int) const;
 380   PropertyManager->Tie("atmosphere/T-R", this,
 381                        &FGAtmosphere::GetTemperature);
 382   PropertyManager->Tie("atmosphere/rho-slugs_ft3", this,
 383                        &FGAtmosphere::GetDensity);
 384   PropertyManager->Tie("atmosphere/P-psf", this,
 385                        &FGAtmosphere::GetPressure);
 386   PropertyManager->Tie("atmosphere/a-fps", this,
 387                        &FGAtmosphere::GetSoundSpeed);
 388   PropertyManager->Tie("atmosphere/T-sl-R", this,
 389                        &FGAtmosphere::GetTemperatureSL);
 390   PropertyManager->Tie("atmosphere/rho-sl-slugs_ft3", this,
 391                        &FGAtmosphere::GetDensitySL);
 392   PropertyManager->Tie("atmosphere/P-sl-psf", this,
 393                        &FGAtmosphere::GetPressureSL);
 394   PropertyManager->Tie("atmosphere/a-sl-fps", this,
 395                        &FGAtmosphere::GetSoundSpeedSL);
 396   PropertyManager->Tie("atmosphere/theta-norm", this,
 397                        &FGAtmosphere::GetTemperatureRatio);
 398   PropertyManager->Tie("atmosphere/sigma-norm", this,
 399                        &FGAtmosphere::GetDensityRatio);
 400   PropertyManager->Tie("atmosphere/delta-norm", this,
 401                        &FGAtmosphere::GetPressureRatio);
 402   PropertyManager->Tie("atmosphere/a-norm", this,
 403                        &FGAtmosphere::GetSoundSpeedRatio);
 404   PropertyManager->Tie("atmosphere/psiw-rad", this,
 405                        &FGAtmosphere::GetWindPsi);
 406   PropertyManager->Tie("atmosphere/p-turb-rad_sec", this,1,
 407                        (PMF)&FGAtmosphere::GetTurbPQR);
 408   PropertyManager->Tie("atmosphere/q-turb-rad_sec", this,2,
 409                        (PMF)&FGAtmosphere::GetTurbPQR);
 410   PropertyManager->Tie("atmosphere/r-turb-rad_sec", this,3,
 411                        (PMF)&FGAtmosphere::GetTurbPQR);
 412 }
 413
 414 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 415
 416 void FGAtmosphere::unbind(void)
 417 {
 418   PropertyManager->Untie("atmosphere/T-R");
 419   PropertyManager->Untie("atmosphere/rho-slugs_ft3");
 420   PropertyManager->Untie("atmosphere/P-psf");
 421   PropertyManager->Untie("atmosphere/a-fps");
 422   PropertyManager->Untie("atmosphere/T-sl-R");
 423   PropertyManager->Untie("atmosphere/rho-sl-slugs_ft3");
 424   PropertyManager->Untie("atmosphere/P-sl-psf");
 425   PropertyManager->Untie("atmosphere/a-sl-fps");
 426   PropertyManager->Untie("atmosphere/theta-norm");
 427   PropertyManager->Untie("atmosphere/sigma-norm");
 428   PropertyManager->Untie("atmosphere/delta-norm");
 429   PropertyManager->Untie("atmosphere/a-norm");
 430   PropertyManager->Untie("atmosphere/psiw-rad");
 431   PropertyManager->Untie("atmosphere/p-turb-rad_sec");
 432   PropertyManager->Untie("atmosphere/q-turb-rad_sec");
 433   PropertyManager->Untie("atmosphere/r-turb-rad_sec");
 434 }
 435
 436 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 437 //    The bitmasked value choices are as follows:
 438 //    unset: In this case (the default) JSBSim would only print
 439 //       out the normally expected messages, essentially echoing
 440 //       the config files as they are read. If the environment
 441 //       variable is not set, debug_lvl is set to 1 internally
 442 //    0: This requests JSBSim not to output any messages
 443 //       whatsoever.
 444 //    1: This value explicity requests the normal JSBSim
 445 //       startup messages
 446 //    2: This value asks for a message to be printed out when
 447 //       a class is instantiated
 448 //    4: When this value is set, a message is displayed when a
 449 //       FGModel object executes its Run() method
 450 //    8: When this value is set, various runtime state variables
 451 //       are printed out periodically
 452 //    16: When set various parameters are sanity checked and
 453 //       a message is printed out when they go out of bounds
 454
 455 void FGAtmosphere::Debug(int from)
 456 {
 457   if (debug_lvl <= 0) return;
 458
 459   if (debug_lvl & 1) { // Standard console startup message output
 460     if (from == 0) { // Constructor
 461     }
 462   }
 463   if (debug_lvl & 2 ) { // Instantiation/Destruction notification
 464     if (from == 0) cout << "Instantiated: FGAtmosphere" << endl;
 465     if (from == 1) cout << "Destroyed:    FGAtmosphere" << endl;
 466   }
 467   if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
 468   }
 469   if (debug_lvl & 8 ) { // Runtime state variables
 470   }
 471   if (debug_lvl & 16) { // Sanity checking
 472   }
 473   if (debug_lvl & 32) { // Turbulence
 474     if (frame == 0 && from == 2) {
 475       cout << "vTurbulence(X), vTurbulence(Y), vTurbulence(Z), "
 476            << "vTurbulenceGrad(X), vTurbulenceGrad(Y), vTurbulenceGrad(Z), "
 477            << "vDirection(X), vDirection(Y), vDirection(Z), "
 478            << "Magnitude, "
 479            << "vTurbPQR(P), vTurbPQR(Q), vTurbPQR(R), " << endl;
 480     } else if (from == 2) {
 481       cout << vTurbulence << ", " << vTurbulenceGrad << ", " << vDirection << ", " << Magnitude << ", " << vTurbPQR << endl;
 482     }
 483   }
 484   if (debug_lvl & 64) {
 485     if (from == 0) { // Constructor
 486       cout << IdSrc << endl;
 487       cout << IdHdr << endl;
 488     }
 489   }
 490 }
 491
 492 } // namespace JSBSim