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