src/FDM/JSBSim/FGAerodynamics.cpp

   1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2
   3  Module:       FGAerodynamics.cpp
   4  Author:       Jon S. Berndt
   5  Date started: 09/13/00
   6  Purpose:      Encapsulates the aerodynamic forces (gear and collision)
   7
   8  ------------- Copyright (C) 2000  Jon S. Berndt (jsb@hal-pc.org) -------------
   9
  10  This program is free software; you can redistribute it and/or modify it under
  11  the terms of the GNU General Public License as published by the Free Software
  12  Foundation; either version 2 of the License, or (at your option) any later
  13  version.
  14
  15  This program is distributed in the hope that it will be useful, but WITHOUT
  16  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  17  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  18  details.
  19
  20  You should have received a copy of the GNU General Public License along with
  21  this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  22  Place - Suite 330, Boston, MA  02111-1307, USA.
  23
  24  Further information about the GNU General Public License can also be found on
  25  the world wide web at http://www.gnu.org.
  26
  27 FUNCTIONAL DESCRIPTION
  28 --------------------------------------------------------------------------------
  29
  30 HISTORY
  31 --------------------------------------------------------------------------------
  32 09/13/00   JSB   Created
  33 04/22/01   JSB   Moved code into here from FGAircraft
  34
  35 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  36 INCLUDES
  37 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  38
  39 #include "FGAerodynamics.h"
  40 #include "FGFactorGroup.h"
  41 #include "FGCoefficient.h"
  42
  43 static const char *IdSrc = "$Id$";
  44 static const char *IdHdr = ID_AERODYNAMICS;
  45
  46 extern short debug_lvl;
  47
  48 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  49 CLASS IMPLEMENTATION
  50 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  51
  52
  53 FGAerodynamics::FGAerodynamics(FGFDMExec* FDMExec) : FGModel(FDMExec),
  54     vMoments(3),
  55     vForces(3),
  56     vFs(3),
  57     vLastFs(3),
  58     vDXYZcg(3)
  59 {
  60   Name = "FGAerodynamics";
  61
  62   AxisIdx["DRAG"]  = 0;
  63   AxisIdx["SIDE"]  = 1;
  64   AxisIdx["LIFT"]  = 2;
  65   AxisIdx["ROLL"]  = 3;
  66   AxisIdx["PITCH"] = 4;
  67   AxisIdx["YAW"]   = 5;
  68
  69   Coeff = new CoeffArray[6];
  70
  71   if (debug_lvl & 2) cout << "Instantiated: FGAerodynamics" << endl;
  72 }
  73
  74 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  75
  76 FGAerodynamics::~FGAerodynamics()
  77 {
  78   unsigned int i,j;
  79   for (i=0; i<6; i++) {
  80     for (j=0; j<Coeff[i].size(); j++) {
  81       delete Coeff[i][j];
  82     }
  83   }
  84   delete[] Coeff;
  85
  86   if (debug_lvl & 2) cout << "Destroyed:    FGAerodynamics" << endl;
  87 }
  88
  89 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  90
  91 bool FGAerodynamics::Run(void)
  92 {
  93   float alpha, beta;
  94   unsigned int axis_ctr,ctr;
  95
  96   if (!FGModel::Run()) {
  97
  98     alpha = Translation->Getalpha();
  99     beta = Translation->Getbeta();
 100
 101     vLastFs = vFs;
 102     vFs.InitMatrix();
 103
 104     for (axis_ctr = 0; axis_ctr < 3; axis_ctr++) {
 105       for (ctr=0; ctr < Coeff[axis_ctr].size(); ctr++) {
 106         vFs(axis_ctr+1) += Coeff[axis_ctr][ctr]->TotalValue();
 107       }
 108     }
 109
 110     vForces = State->GetTs2b(alpha, beta)*vFs;
 111
 112     // see http://home.earthlink.net/~apeden/jsbsim_moments_due_to_forces.txt
 113     // for details on this
 114
 115     vDXYZcg(eX) = -(Aircraft->GetXYZrp(eX) - MassBalance->GetXYZcg(eX))/12.0;
 116     vDXYZcg(eY) =  (Aircraft->GetXYZrp(eY) - MassBalance->GetXYZcg(eY))/12.0;
 117     vDXYZcg(eZ) = -(Aircraft->GetXYZrp(eZ) - MassBalance->GetXYZcg(eZ))/12.0;
 118
 119     vMoments(eL) = vForces(eZ)*vDXYZcg(eY) - vForces(eY)*vDXYZcg(eZ);
 120     vMoments(eM) = vForces(eX)*vDXYZcg(eZ) - vForces(eZ)*vDXYZcg(eX);
 121     vMoments(eN) = vForces(eY)*vDXYZcg(eX) - vForces(eX)*vDXYZcg(eY);
 122
 123     for (axis_ctr = 0; axis_ctr < 3; axis_ctr++) {
 124       for (ctr = 0; ctr < Coeff[axis_ctr+3].size(); ctr++) {
 125         vMoments(axis_ctr+1) += Coeff[axis_ctr+3][ctr]->TotalValue();
 126       }
 127     }
 128     return false;
 129   } else {
 130     return true;
 131   }
 132 }
 133
 134 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 135
 136 bool FGAerodynamics::Load(FGConfigFile* AC_cfg)
 137 {
 138   string token, axis;
 139
 140   AC_cfg->GetNextConfigLine();
 141
 142   while ((token = AC_cfg->GetValue()) != "/AERODYNAMICS") {
 143     if (token == "AXIS") {
 144       CoeffArray ca;
 145       axis = AC_cfg->GetValue("NAME");
 146       AC_cfg->GetNextConfigLine();
 147       while ((token = AC_cfg->GetValue()) != "/AXIS") {
 148         if( token == "COEFFICIENT" ) {
 149           ca.push_back( new FGCoefficient(FDMExec) );
 150           ca.back()->Load(AC_cfg);
 151         } else if ( token == "GROUP" ) {
 152           ca.push_back( new FGFactorGroup(FDMExec) );
 153           ca.back()->Load(AC_cfg);
 154         }
 155       }
 156       Coeff[AxisIdx[axis]] = ca;
 157       AC_cfg->GetNextConfigLine();
 158     }
 159   }
 160
 161   return true;
 162 }
 163
 164 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 165
 166 string FGAerodynamics::GetCoefficientStrings(void)
 167 {
 168   string CoeffStrings = "";
 169   bool firstime = true;
 170   unsigned int axis, sd;
 171
 172   for (axis = 0; axis < 6; axis++) {
 173     for (sd = 0; sd < Coeff[axis].size(); sd++) {
 174       if (firstime) {
 175         firstime = false;
 176       } else {
 177         CoeffStrings += ", ";
 178       }
 179       CoeffStrings += Coeff[axis][sd]->GetCoefficientStrings();
 180     }
 181   }
 182   return CoeffStrings;
 183 }
 184
 185 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 186
 187 string FGAerodynamics::GetCoefficientValues(void)
 188 {
 189   string SDValues = "";
 190   char buffer[10];
 191   bool firstime = true;
 192
 193   for (unsigned int axis = 0; axis < 6; axis++) {
 194     for (unsigned int sd = 0; sd < Coeff[axis].size(); sd++) {
 195       if (firstime) {
 196         firstime = false;
 197       } else {
 198         SDValues += ", ";
 199       }
 200       SDValues += Coeff[axis][sd]->GetCoefficientValues();
 201     }
 202   }
 203
 204   return SDValues;
 205 }
 206
 207 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 208
 209 float FGAerodynamics::GetNlf(void)
 210 {
 211   if (fabs(Position->GetGamma()) < 1.57) {
 212     return (vFs(eZ)/(MassBalance->GetWeight()*cos(Position->GetGamma())));
 213   } else {
 214     return 0.0;
 215   }
 216 }
 217
 218 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 219
 220 float FGAerodynamics::GetLoD(void)
 221 {
 222   float LoD;
 223
 224   if (vFs(1) != 0.00) return vFs(3)/vFs(1);
 225   else                return 0.00;
 226 }
 227
 228 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 229
 230 void FGAerodynamics::Debug(void)
 231 {
 232     //TODO: Add your source code here
 233 }
 234