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 = ttBerndt;
  93   TurbGain = 0.0;
  94
  95   bind();
  96   Debug(0);
  97 }
  98
  99 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 100
 101 FGAtmosphere::~FGAtmosphere()
 102 {
 103   unbind();
 104   Debug(1);
 105 }
 106
 107 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 108
 109 bool FGAtmosphere::InitModel(void)
 110 {
 111   FGModel::InitModel();
 112
 113   Calculate(h);
 114   SLtemperature = intTemperature;
 115   SLpressure    = intPressure;
 116   SLdensity     = intDensity;
 117   SLsoundspeed  = sqrt(SHRatio*Reng*intTemperature);
 118   rSLtemperature = 1.0/intTemperature;
 119   rSLpressure    = 1.0/intPressure;
 120   rSLdensity     = 1.0/intDensity;
 121   rSLsoundspeed  = 1.0/SLsoundspeed;
 122   temperature=&intTemperature;
 123   pressure=&intPressure;
 124   density=&intDensity;
 125
 126   useExternal=false;
 127
 128   return true;
 129 }
 130
 131 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 132
 133 bool FGAtmosphere::Run(void)
 134 {
 135   if (!FGModel::Run()) {                 // if false then execute this Run()
 136     //do temp, pressure, and density first
 137     if (!useExternal) {
 138       h = Position->Geth();
 139       Calculate(h);
 140     }
 141
 142     if (turbType != ttNone) {
 143       Turbulence();
 144       vWindNED += vTurbulence;
 145     }
 146
 147     if (vWindNED(1) != 0.0) psiw = atan2( vWindNED(2), vWindNED(1) );
 148
 149     if (psiw < 0) psiw += 2*M_PI;
 150
 151     soundspeed = sqrt(SHRatio*Reng*(*temperature));
 152
 153     State->Seta(soundspeed);
 154
 155     Debug(2);
 156
 157         return false;
 158   } else {                               // skip Run() execution this time
 159         return true;
 160   }
 161 }
 162
 163 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 164 //
 165 // See reference 1
 166
 167 void FGAtmosphere::Calculate(double altitude)
 168 {
 169   double slope, reftemp, refpress;
 170   int i = 0;
 171
 172   i = lastIndex;
 173   if (altitude < htab[lastIndex]) {
 174     if (altitude <= 0) {
 175       i = 0;
 176       altitude=0;
 177     } else {
 178        i = lastIndex-1;
 179        while (htab[i] > altitude) i--;
 180     }
 181   } else if (altitude > htab[lastIndex+1]) {
 182     if (altitude >= htab[7]) {
 183       i = 7;
 184       altitude = htab[7];
 185     } else {
 186       i = lastIndex+1;
 187       while (htab[i+1] < altitude) i++;
 188     }
 189   }
 190
 191   switch(i) {
 192   case 1:     // 36089 ft.
 193     slope     = 0;
 194     reftemp   = 389.97;
 195     refpress  = 472.452;
 196     //refdens   = 0.000706032;
 197     break;
 198   case 2:     // 65616 ft.
 199     slope     = 0.00054864;
 200     reftemp   = 389.97;
 201     refpress  = 114.636;
 202     //refdens   = 0.000171306;
 203     break;
 204   case 3:     // 104986 ft.
 205     slope     = 0.00153619;
 206     reftemp   = 411.57;
 207     refpress  = 8.36364;
 208     //refdens   = 1.18422e-05;
 209     break;
 210   case 4:     // 154199 ft.
 211     slope     = 0;
 212     reftemp   = 487.17;
 213     refpress  = 0.334882;
 214     //refdens   = 4.00585e-7;
 215     break;
 216   case 5:     // 170603 ft.
 217     slope     = -0.00109728;
 218     reftemp   = 487.17;
 219     refpress  = 0.683084;
 220     //refdens   = 8.17102e-7;
 221     break;
 222   case 6:     // 200131 ft.
 223     slope     = -0.00219456;
 224     reftemp   = 454.17;
 225     refpress  = 0.00684986;
 226     //refdens   = 8.77702e-9;
 227     break;
 228   case 7:     // 259186 ft.
 229     slope     = 0;
 230     reftemp   = 325.17;
 231     refpress  = 0.000122276;
 232     //refdens   = 2.19541e-10;
 233     break;
 234   case 0:
 235   default:     // sea level
 236     slope     = -0.00356616; // R/ft.
 237     reftemp   = 518.67;    // R
 238     refpress  = 2116.22;    // psf
 239     //refdens   = 0.00237767;  // slugs/cubic ft.
 240     break;
 241
 242   }
 243
 244   if (slope == 0) {
 245     intTemperature = reftemp;
 246     intPressure = refpress*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
 247     //intDensity = refdens*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
 248     intDensity = intPressure/(Reng*intTemperature);
 249   } else {
 250     intTemperature = reftemp+slope*(altitude-htab[i]);
 251     intPressure = refpress*pow(intTemperature/reftemp,-Inertial->SLgravity()/(slope*Reng));
 252     //intDensity = refdens*pow(intTemperature/reftemp,-(Inertial->SLgravity()/(slope*Reng)+1));
 253     intDensity = intPressure/(Reng*intTemperature);
 254   }
 255   lastIndex=i;
 256   //cout << "Atmosphere:  h=" << altitude << " rho= " << intDensity << endl;
 257 }
 258
 259 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 260
 261 void FGAtmosphere::Turbulence(void)
 262 {
 263   switch (turbType) {
 264   case ttBerndt: {
 265     vDirectiondAccelDt(eX) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
 266     vDirectiondAccelDt(eY) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
 267     vDirectiondAccelDt(eZ) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
 268
 269
 270     MagnitudedAccelDt = 1 - 2.0*(((double)(rand()))/RAND_MAX) - Magnitude;
 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                                 // Diminish z-vector within two wingspans
 280                                 // of the ground
 281     double HOverBMAC = Position->GetHOverBMAC();
 282     if (HOverBMAC < 2.0)
 283         vDirection(eZ) *= HOverBMAC / 2.0;
 284
 285     vDirection.Normalize();
 286
 287     vTurbulence = TurbGain*Magnitude * vDirection;
 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     break;
 303   }
 304   default:
 305     break;
 306   }
 307 }
 308
 309 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 310
 311 void FGAtmosphere::UseExternal(void) {
 312   temperature=&exTemperature;
 313   pressure=&exPressure;
 314   density=&exDensity;
 315   useExternal=true;
 316 }
 317
 318 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 319
 320 void FGAtmosphere::UseInternal(void) {
 321   temperature=&intTemperature;
 322   pressure=&intPressure;
 323   density=&intDensity;
 324   useExternal=false;
 325 }
 326
 327
 328 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 329
 330 void FGAtmosphere::bind(void)
 331 {
 332   typedef double (FGAtmosphere::*PMF)(int) const;
 333   PropertyManager->Tie("atmosphere/T-R", this,
 334                        &FGAtmosphere::GetTemperature);
 335   PropertyManager->Tie("atmosphere/rho-slugs_ft3", this,
 336                        &FGAtmosphere::GetDensity);
 337   PropertyManager->Tie("atmosphere/P-psf", this,
 338                        &FGAtmosphere::GetPressure);
 339   PropertyManager->Tie("atmosphere/a-fps", this,
 340                        &FGAtmosphere::GetSoundSpeed);
 341   PropertyManager->Tie("atmosphere/T-sl-R", this,
 342                        &FGAtmosphere::GetTemperatureSL);
 343   PropertyManager->Tie("atmosphere/rho-sl-slugs_ft3", this,
 344                        &FGAtmosphere::GetDensitySL);
 345   PropertyManager->Tie("atmosphere/P-sl-psf", this,
 346                        &FGAtmosphere::GetPressureSL);
 347   PropertyManager->Tie("atmosphere/a-sl-fps", this,
 348                        &FGAtmosphere::GetSoundSpeedSL);
 349   PropertyManager->Tie("atmosphere/theta-norm", this,
 350                        &FGAtmosphere::GetTemperatureRatio);
 351   PropertyManager->Tie("atmosphere/sigma-norm", this,
 352                        &FGAtmosphere::GetDensityRatio);
 353   PropertyManager->Tie("atmosphere/delta-norm", this,
 354                        &FGAtmosphere::GetPressureRatio);
 355   PropertyManager->Tie("atmosphere/a-norm", this,
 356                        &FGAtmosphere::GetSoundSpeedRatio);
 357   PropertyManager->Tie("atmosphere/psiw-rad", this,
 358                        &FGAtmosphere::GetWindPsi);
 359   PropertyManager->Tie("atmosphere/p-turb-rad_sec", this,1,
 360                        (PMF)&FGAtmosphere::GetTurbPQR);
 361   PropertyManager->Tie("atmosphere/q-turb-rad_sec", this,2,
 362                        (PMF)&FGAtmosphere::GetTurbPQR);
 363   PropertyManager->Tie("atmosphere/r-turb-rad_sec", this,3,
 364                        (PMF)&FGAtmosphere::GetTurbPQR);
 365 }
 366
 367 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 368
 369 void FGAtmosphere::unbind(void)
 370 {
 371   PropertyManager->Untie("atmosphere/T-R");
 372   PropertyManager->Untie("atmosphere/rho-slugs_ft3");
 373   PropertyManager->Untie("atmosphere/P-psf");
 374   PropertyManager->Untie("atmosphere/a-fps");
 375   PropertyManager->Untie("atmosphere/T-sl-R");
 376   PropertyManager->Untie("atmosphere/rho-sl-slugs_ft3");
 377   PropertyManager->Untie("atmosphere/P-sl-psf");
 378   PropertyManager->Untie("atmosphere/a-sl-fps");
 379   PropertyManager->Untie("atmosphere/theta-norm");
 380   PropertyManager->Untie("atmosphere/sigma-norm");
 381   PropertyManager->Untie("atmosphere/delta-norm");
 382   PropertyManager->Untie("atmosphere/a-norm");
 383   PropertyManager->Untie("atmosphere/psiw-rad");
 384   PropertyManager->Untie("atmosphere/p-turb-rad_sec");
 385   PropertyManager->Untie("atmosphere/q-turb-rad_sec");
 386   PropertyManager->Untie("atmosphere/r-turb-rad_sec");
 387 }
 388
 389 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 390 //    The bitmasked value choices are as follows:
 391 //    unset: In this case (the default) JSBSim would only print
 392 //       out the normally expected messages, essentially echoing
 393 //       the config files as they are read. If the environment
 394 //       variable is not set, debug_lvl is set to 1 internally
 395 //    0: This requests JSBSim not to output any messages
 396 //       whatsoever.
 397 //    1: This value explicity requests the normal JSBSim
 398 //       startup messages
 399 //    2: This value asks for a message to be printed out when
 400 //       a class is instantiated
 401 //    4: When this value is set, a message is displayed when a
 402 //       FGModel object executes its Run() method
 403 //    8: When this value is set, various runtime state variables
 404 //       are printed out periodically
 405 //    16: When set various parameters are sanity checked and
 406 //       a message is printed out when they go out of bounds
 407
 408 void FGAtmosphere::Debug(int from)
 409 {
 410   if (debug_lvl <= 0) return;
 411
 412   if (debug_lvl & 1) { // Standard console startup message output
 413     if (from == 0) { // Constructor
 414     }
 415   }
 416   if (debug_lvl & 2 ) { // Instantiation/Destruction notification
 417     if (from == 0) cout << "Instantiated: FGAtmosphere" << endl;
 418     if (from == 1) cout << "Destroyed:    FGAtmosphere" << endl;
 419   }
 420   if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
 421   }
 422   if (debug_lvl & 8 ) { // Runtime state variables
 423   }
 424   if (debug_lvl & 16) { // Sanity checking
 425   }
 426   if (debug_lvl & 32) { // Turbulence
 427     if (frame == 0 && from == 2) {
 428       cout << "vTurbulence(X), vTurbulence(Y), vTurbulence(Z), "
 429            << "vTurbulenceGrad(X), vTurbulenceGrad(Y), vTurbulenceGrad(Z), "
 430            << "vDirection(X), vDirection(Y), vDirection(Z), "
 431            << "Magnitude, "
 432            << "vTurbPQR(P), vTurbPQR(Q), vTurbPQR(R), " << endl;
 433     } else if (from == 2) {
 434       cout << vTurbulence << ", " << vTurbulenceGrad << ", " << vDirection << ", " << Magnitude << ", " << vTurbPQR << endl;
 435     }
 436   }
 437   if (debug_lvl & 64) {
 438     if (from == 0) { // Constructor
 439       cout << IdSrc << endl;
 440       cout << IdHdr << endl;
 441     }
 442   }
 443 }
 444
 445 } // namespace JSBSim