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 static const char *IdSrc = "$Id$";
  66 static const char *IdHdr = ID_ATMOSPHERE;
  67
  68 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  69 CLASS IMPLEMENTATION
  70 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  71
  72
  73 FGAtmosphere::FGAtmosphere(FGFDMExec* fdmex) : FGModel(fdmex)
  74 {
  75   Name = "FGAtmosphere";
  76   lastIndex = 0;
  77   h = 0.0;
  78   psiw = 0.0;
  79   htab[0]=0;
  80   htab[1]=36089.239;
  81   htab[2]=65616.798;
  82   htab[3]=104986.878;
  83   htab[4]=154199.475;
  84   htab[5]=170603.675;
  85   htab[6]=200131.234;
  86   htab[7]=259186.352; //ft.
  87
  88   MagnitudedAccelDt = MagnitudeAccel = Magnitude = 0.0;
  89   turbType = ttNone;
  90 //  turbType = ttBerndt; // temporarily disable turbulence until fully tested
  91   TurbGain = 100.0;
  92
  93   bind();
  94   Debug(0);
  95 }
  96
  97 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  98
  99 FGAtmosphere::~FGAtmosphere()
 100 {
 101   unbind();
 102   Debug(1);
 103 }
 104
 105 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 106
 107 bool FGAtmosphere::InitModel(void)
 108 {
 109   FGModel::InitModel();
 110
 111   Calculate(h);
 112   SLtemperature = intTemperature;
 113   SLpressure    = intPressure;
 114   SLdensity     = intDensity;
 115   SLsoundspeed  = sqrt(SHRatio*Reng*intTemperature);
 116   rSLtemperature = 1.0/intTemperature;
 117   rSLpressure    = 1.0/intPressure;
 118   rSLdensity     = 1.0/intDensity;
 119   rSLsoundspeed  = 1.0/SLsoundspeed;
 120   temperature=&intTemperature;
 121   pressure=&intPressure;
 122   density=&intDensity;
 123
 124   useExternal=false;
 125
 126   return true;
 127 }
 128
 129 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 130
 131 bool FGAtmosphere::Run(void)
 132 {
 133   if (!FGModel::Run()) {                 // if false then execute this Run()
 134     //do temp, pressure, and density first
 135     if (!useExternal) {
 136       h = Position->Geth();
 137       Calculate(h);
 138     }
 139
 140     if (turbType != ttNone) {
 141       Turbulence();
 142       vWindNED += vTurbulence;
 143     }
 144
 145     if (vWindNED(1) != 0.0) psiw = atan2( vWindNED(2), vWindNED(1) );
 146
 147     if (psiw < 0) psiw += 2*M_PI;
 148
 149     soundspeed = sqrt(SHRatio*Reng*(*temperature));
 150
 151     State->Seta(soundspeed);
 152
 153     Debug(2);
 154
 155         return false;
 156   } else {                               // skip Run() execution this time
 157         return true;
 158   }
 159 }
 160
 161 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 162 //
 163 // See reference 1
 164
 165 void FGAtmosphere::Calculate(double altitude)
 166 {
 167   double slope, reftemp, refpress;
 168   int i = 0;
 169
 170   i = lastIndex;
 171   if (altitude < htab[lastIndex]) {
 172     if (altitude <= 0) {
 173       i = 0;
 174       altitude=0;
 175     } else {
 176        i = lastIndex-1;
 177        while (htab[i] > altitude) i--;
 178     }
 179   } else if (altitude > htab[lastIndex+1]) {
 180     if (altitude >= htab[7]) {
 181       i = 7;
 182       altitude = htab[7];
 183     } else {
 184       i = lastIndex+1;
 185       while (htab[i+1] < altitude) i++;
 186     }
 187   }
 188
 189   switch(i) {
 190   case 1:     // 36089 ft.
 191     slope     = 0;
 192     reftemp   = 389.97;
 193     refpress  = 472.452;
 194     //refdens   = 0.000706032;
 195     break;
 196   case 2:     // 65616 ft.
 197     slope     = 0.00054864;
 198     reftemp   = 389.97;
 199     refpress  = 114.636;
 200     //refdens   = 0.000171306;
 201     break;
 202   case 3:     // 104986 ft.
 203     slope     = 0.00153619;
 204     reftemp   = 411.57;
 205     refpress  = 8.36364;
 206     //refdens   = 1.18422e-05;
 207     break;
 208   case 4:     // 154199 ft.
 209     slope     = 0;
 210     reftemp   = 487.17;
 211     refpress  = 0.334882;
 212     //refdens   = 4.00585e-7;
 213     break;
 214   case 5:     // 170603 ft.
 215     slope     = -0.00109728;
 216     reftemp   = 487.17;
 217     refpress  = 0.683084;
 218     //refdens   = 8.17102e-7;
 219     break;
 220   case 6:     // 200131 ft.
 221     slope     = -0.00219456;
 222     reftemp   = 454.17;
 223     refpress  = 0.00684986;
 224     //refdens   = 8.77702e-9;
 225     break;
 226   case 7:     // 259186 ft.
 227     slope     = 0;
 228     reftemp   = 325.17;
 229     refpress  = 0.000122276;
 230     //refdens   = 2.19541e-10;
 231     break;
 232   case 0:
 233   default:     // sea level
 234     slope     = -0.00356616; // R/ft.
 235     reftemp   = 518.67;    // R
 236     refpress  = 2116.22;    // psf
 237     //refdens   = 0.00237767;  // slugs/cubic ft.
 238     break;
 239
 240   }
 241
 242   if (slope == 0) {
 243     intTemperature = reftemp;
 244     intPressure = refpress*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
 245     //intDensity = refdens*exp(-Inertial->SLgravity()/(reftemp*Reng)*(altitude-htab[i]));
 246     intDensity = intPressure/(Reng*intTemperature);
 247   } else {
 248     intTemperature = reftemp+slope*(altitude-htab[i]);
 249     intPressure = refpress*pow(intTemperature/reftemp,-Inertial->SLgravity()/(slope*Reng));
 250     //intDensity = refdens*pow(intTemperature/reftemp,-(Inertial->SLgravity()/(slope*Reng)+1));
 251     intDensity = intPressure/(Reng*intTemperature);
 252   }
 253   lastIndex=i;
 254   //cout << "Atmosphere:  h=" << altitude << " rho= " << intDensity << endl;
 255 }
 256
 257 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 258
 259 void FGAtmosphere::Turbulence(void)
 260 {
 261   switch (turbType) {
 262   case ttBerndt:
 263     vDirectiondAccelDt(eX) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
 264     vDirectiondAccelDt(eY) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
 265     vDirectiondAccelDt(eZ) = 1 - 2.0*(((double)(rand()))/RAND_MAX);
 266
 267     MagnitudedAccelDt = 1 - 2.0*(((double)(rand()))/RAND_MAX);
 268     MagnitudeAccel    += MagnitudedAccelDt*rate*State->Getdt();
 269     Magnitude         += MagnitudeAccel*rate*State->Getdt();
 270
 271     vDirectiondAccelDt.Normalize();
 272     vDirectionAccel += vDirectiondAccelDt*rate*State->Getdt();
 273     vDirectionAccel.Normalize();
 274     vDirection      += vDirectionAccel*rate*State->Getdt();
 275     vDirection.Normalize();
 276
 277     vTurbulence = TurbGain*Magnitude * vDirection;
 278     vTurbulenceGrad = TurbGain*MagnitudeAccel * vDirection;
 279
 280     vBodyTurbGrad = State->GetTl2b()*vTurbulenceGrad;
 281     vTurbPQR(eP) = vBodyTurbGrad(eY)/Aircraft->GetWingSpan();
 282     if (Aircraft->GetHTailArm() != 0.0)
 283       vTurbPQR(eQ) = vBodyTurbGrad(eZ)/Aircraft->GetHTailArm();
 284     else
 285       vTurbPQR(eQ) = vBodyTurbGrad(eZ)/10.0;
 286
 287     if (Aircraft->GetVTailArm())
 288       vTurbPQR(eR) = vBodyTurbGrad(eX)/Aircraft->GetVTailArm();
 289     else
 290       vTurbPQR(eR) = vBodyTurbGrad(eX)/10.0;
 291
 292     break;
 293   default:
 294     break;
 295   }
 296 }
 297
 298 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 299
 300 void FGAtmosphere::UseExternal(void) {
 301   temperature=&exTemperature;
 302   pressure=&exPressure;
 303   density=&exDensity;
 304   useExternal=true;
 305 }
 306
 307 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 308
 309 void FGAtmosphere::UseInternal(void) {
 310   temperature=&intTemperature;
 311   pressure=&intPressure;
 312   density=&intDensity;
 313   useExternal=false;
 314 }
 315
 316
 317 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 318
 319 void FGAtmosphere::bind(void)
 320 {
 321   typedef double (FGAtmosphere::*PMF)(int) const;
 322   PropertyManager->Tie("atmosphere/T-R", this,
 323                        &FGAtmosphere::GetTemperature);
 324   PropertyManager->Tie("atmosphere/rho-slugs_ft3", this,
 325                        &FGAtmosphere::GetDensity);
 326   PropertyManager->Tie("atmosphere/P-psf", this,
 327                        &FGAtmosphere::GetPressure);
 328   PropertyManager->Tie("atmosphere/a-fps", this,
 329                        &FGAtmosphere::GetSoundSpeed);
 330   PropertyManager->Tie("atmosphere/T-sl-R", this,
 331                        &FGAtmosphere::GetTemperatureSL);
 332   PropertyManager->Tie("atmosphere/rho-sl-slugs_ft3", this,
 333                        &FGAtmosphere::GetDensitySL);
 334   PropertyManager->Tie("atmosphere/P-sl-psf", this,
 335                        &FGAtmosphere::GetPressureSL);
 336   PropertyManager->Tie("atmosphere/a-sl-fps", this,
 337                        &FGAtmosphere::GetSoundSpeedSL);
 338   PropertyManager->Tie("atmosphere/theta-norm", this,
 339                        &FGAtmosphere::GetTemperatureRatio);
 340   PropertyManager->Tie("atmosphere/sigma-norm", this,
 341                        &FGAtmosphere::GetDensityRatio);
 342   PropertyManager->Tie("atmosphere/delta-norm", this,
 343                        &FGAtmosphere::GetPressureRatio);
 344   PropertyManager->Tie("atmosphere/a-norm", this,
 345                        &FGAtmosphere::GetSoundSpeedRatio);
 346   PropertyManager->Tie("atmosphere/psiw-rad", this,
 347                        &FGAtmosphere::GetWindPsi);
 348   PropertyManager->Tie("atmosphere/p-turb-rad_sec", this,1,
 349                        (PMF)&FGAtmosphere::GetTurbPQR);
 350   PropertyManager->Tie("atmosphere/q-turb-rad_sec", this,2,
 351                        (PMF)&FGAtmosphere::GetTurbPQR);
 352   PropertyManager->Tie("atmosphere/r-turb-rad_sec", this,3,
 353                        (PMF)&FGAtmosphere::GetTurbPQR);
 354 }
 355
 356 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 357
 358 void FGAtmosphere::unbind(void)
 359 {
 360   PropertyManager->Untie("atmosphere/T-R");
 361   PropertyManager->Untie("atmosphere/rho-slugs_ft3");
 362   PropertyManager->Untie("atmosphere/P-psf");
 363   PropertyManager->Untie("atmosphere/a-fps");
 364   PropertyManager->Untie("atmosphere/T-sl-R");
 365   PropertyManager->Untie("atmosphere/rho-sl-slugs_ft3");
 366   PropertyManager->Untie("atmosphere/P-sl-psf");
 367   PropertyManager->Untie("atmosphere/a-sl-fps");
 368   PropertyManager->Untie("atmosphere/theta-norm");
 369   PropertyManager->Untie("atmosphere/sigma-norm");
 370   PropertyManager->Untie("atmosphere/delta-norm");
 371   PropertyManager->Untie("atmosphere/a-norm");
 372   PropertyManager->Untie("atmosphere/psiw-rad");
 373   PropertyManager->Untie("atmosphere/p-turb-rad_sec");
 374   PropertyManager->Untie("atmosphere/q-turb-rad_sec");
 375   PropertyManager->Untie("atmosphere/r-turb-rad_sec");
 376 }
 377
 378 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 379 //    The bitmasked value choices are as follows:
 380 //    unset: In this case (the default) JSBSim would only print
 381 //       out the normally expected messages, essentially echoing
 382 //       the config files as they are read. If the environment
 383 //       variable is not set, debug_lvl is set to 1 internally
 384 //    0: This requests JSBSim not to output any messages
 385 //       whatsoever.
 386 //    1: This value explicity requests the normal JSBSim
 387 //       startup messages
 388 //    2: This value asks for a message to be printed out when
 389 //       a class is instantiated
 390 //    4: When this value is set, a message is displayed when a
 391 //       FGModel object executes its Run() method
 392 //    8: When this value is set, various runtime state variables
 393 //       are printed out periodically
 394 //    16: When set various parameters are sanity checked and
 395 //       a message is printed out when they go out of bounds
 396
 397 void FGAtmosphere::Debug(int from)
 398 {
 399   if (debug_lvl <= 0) return;
 400
 401   if (debug_lvl & 1) { // Standard console startup message output
 402     if (from == 0) { // Constructor
 403     }
 404   }
 405   if (debug_lvl & 2 ) { // Instantiation/Destruction notification
 406     if (from == 0) cout << "Instantiated: FGAtmosphere" << endl;
 407     if (from == 1) cout << "Destroyed:    FGAtmosphere" << endl;
 408   }
 409   if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
 410   }
 411   if (debug_lvl & 8 ) { // Runtime state variables
 412   }
 413   if (debug_lvl & 16) { // Sanity checking
 414   }
 415   if (debug_lvl & 32) { // Turbulence
 416     if (frame == 0 && from == 2) {
 417       cout << "vTurbulence(X), vTurbulence(Y), vTurbulence(Z), "
 418            << "vTurbulenceGrad(X), vTurbulenceGrad(Y), vTurbulenceGrad(Z), "
 419            << "vDirection(X), vDirection(Y), vDirection(Z), "
 420            << "Magnitude, "
 421            << "vTurbPQR(P), vTurbPQR(Q), vTurbPQR(R), " << endl;
 422     } else if (from == 2) {
 423       cout << vTurbulence << ", " << vTurbulenceGrad << ", " << vDirection << ", " << Magnitude << ", " << vTurbPQR << endl;
 424     }
 425   }
 426   if (debug_lvl & 64) {
 427     if (from == 0) { // Constructor
 428       cout << IdSrc << endl;
 429       cout << IdHdr << endl;
 430     }
 431   }
 432 }
 433