src/FDM/JSBSim/FGAuxiliary.cpp

   1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2
   3  Module:       FGAuxiliary.cpp
   4  Author:       Tony Peden, Jon Berndt
   5  Date started: 01/26/99
   6  Purpose:      Calculates additional parameters needed by the visual system, etc.
   7  Called by:    FGSimExec
   8
   9  ------------- Copyright (C) 1999  Jon S. Berndt (jsb@hal-pc.org) -------------
  10
  11  This program is free software; you can redistribute it and/or modify it under
  12  the terms of the GNU General Public License as published by the Free Software
  13  Foundation; either version 2 of the License, or (at your option) any later
  14  version.
  15
  16  This program is distributed in the hope that it will be useful, but WITHOUT
  17  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  18  FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  19  details.
  20
  21  You should have received a copy of the GNU General Public License along with
  22  this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  23  Place - Suite 330, Boston, MA  02111-1307, USA.
  24
  25  Further information about the GNU General Public License can also be found on
  26  the world wide web at http://www.gnu.org.
  27
  28 FUNCTIONAL DESCRIPTION
  29 --------------------------------------------------------------------------------
  30 This class calculates various auxiliary parameters.
  31
  32 REFERENCES
  33   Anderson, John D. "Introduction to Flight", 3rd Edition, McGraw-Hill, 1989
  34                     pgs. 112-126
  35 HISTORY
  36 --------------------------------------------------------------------------------
  37 01/26/99   JSB   Created
  38
  39 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  40 INCLUDES
  41 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  42
  43 #include "FGAuxiliary.h"
  44 #include "FGTranslation.h"
  45 #include "FGRotation.h"
  46 #include "FGAtmosphere.h"
  47 #include "FGState.h"
  48 #include "FGFDMExec.h"
  49 #include "FGFCS.h"
  50 #include "FGAircraft.h"
  51 #include "FGPosition.h"
  52 #include "FGOutput.h"
  53 #include "FGMatrix.h"
  54
  55 static const char *IdSrc = "$Id$";
  56 static const char *IdHdr = ID_AUXILIARY;
  57
  58 extern short debug_lvl;
  59
  60 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  61 CLASS IMPLEMENTATION
  62 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
  63
  64
  65 FGAuxiliary::FGAuxiliary(FGFDMExec* fdmex) : FGModel(fdmex),
  66   vPilotAccel(3),
  67   vToEyePt(3)
  68 {
  69   Name = "FGAuxiliary";
  70   vcas = veas = mach = qbar = pt = 0;
  71   psl = rhosl = 1;
  72   earthPosAngle = 0.0;
  73
  74   if (debug_lvl & 2) cout << "Instantiated: " << Name << endl;
  75 }
  76
  77 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  78
  79 FGAuxiliary::~FGAuxiliary()
  80 {
  81   if (debug_lvl & 2) cout << "Destroyed:    FGAuxiliary" << endl;
  82 }
  83
  84 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  85
  86 bool FGAuxiliary::Run()
  87 {
  88   float A,B,D;
  89
  90   if (!FGModel::Run()) {
  91     GetState();
  92     if (mach < 1) {   //calculate total pressure assuming isentropic flow
  93       pt=p*pow((1 + 0.2*mach*mach),3.5);
  94     } else {
  95       // shock in front of pitot tube, we'll assume its normal and use
  96       // the Rayleigh Pitot Tube Formula, i.e. the ratio of total
  97       // pressure behind the shock to the static pressure in front
  98
  99       B = 5.76*mach*mach/(5.6*mach*mach - 0.8);
 100
 101       // The denominator above is zero for Mach ~ 0.38, for which
 102       // we'll never be here, so we're safe
 103
 104       D = (2.8*mach*mach-0.4)*0.4167;
 105       pt = p*pow(B,3.5)*D;
 106     }
 107
 108     A = pow(((pt-p)/psl+1),0.28571);
 109     vcas = sqrt(7*psl/rhosl*(A-1));
 110     veas = sqrt(2*qbar/rhosl);
 111
 112     // vPilotAccel = Translation->GetUVWdot() + Aircraft->GetXYZep() * Rotation->GetPQRdot();
 113
 114     vToEyePt = Aircraft->GetXYZep() - MassBalance->GetXYZcg();
 115     vPilotAccel = Translation->GetUVWdot()
 116                     + Rotation->GetPQRdot() * vToEyePt
 117                     + Rotation->GetPQR() * (Rotation->GetPQR() * vToEyePt);
 118
 119     earthPosAngle += State->Getdt()*OMEGA_EARTH;
 120     return false;
 121   } else {
 122     return true;
 123   }
 124 }
 125
 126 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 127
 128 float FGAuxiliary::GetHeadWind(void)
 129 {
 130   float psiw,vw,psi;
 131
 132   psiw = Atmosphere->GetWindPsi();
 133   psi = Rotation->Getpsi();
 134   vw = Atmosphere->GetWindNED().Magnitude();
 135
 136   return -vw*cos(psiw - psi);
 137 }
 138
 139 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 140
 141 float FGAuxiliary::GetCrossWind(void)
 142 {
 143   float psiw,vw,psi;
 144
 145   psiw = Atmosphere->GetWindPsi();
 146   psi = Rotation->Getpsi();
 147   vw = Atmosphere->GetWindNED().Magnitude();
 148
 149   return  vw*sin(psiw - psi);
 150 }
 151
 152 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 153
 154 void FGAuxiliary::GetState(void)
 155 {
 156   qbar = Translation->Getqbar();
 157   mach = Translation->GetMach();
 158   p = Atmosphere->GetPressure();
 159   rhosl = Atmosphere->GetDensitySL();
 160   psl = Atmosphere->GetPressureSL();
 161 }
 162
 163 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 164
 165 void FGAuxiliary::Debug(void)
 166 {
 167     //TODO: Add your source code here
 168 }
 169