src/FDM/JSBSim/JSBSim.cxx

   1 // JSBsim.cxx -- interface to the JSBsim flight model
   2 //
   3 // Written by Curtis Olson, started February 1999.
   4 //
   5 // Copyright (C) 1999  Curtis L. Olson  - curt@flightgear.org
   6 //
   7 // This program is free software; you can redistribute it and/or
   8 // modify it under the terms of the GNU Lesser General Public License as
   9 // published by the Free Software Foundation; either version 2 of the
  10 // License, or (at your option) any later version.
  11 //
  12 // This program is distributed in the hope that it will be useful, but
  13 // WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 // Lesser General Public License for more details.
  16 //
  17 // You should have received a copy of the GNU Lesser General Public License
  18 // along with this program; if not, write to the Free Software
  19 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 //
  21 // $Id: JSBSim.cxx,v 1.64 2010/10/31 04:49:25 jberndt Exp $
  22
  23
  24 #ifdef HAVE_CONFIG_H
  25 #  include <config.h>
  26 #endif
  27
  28 #include <simgear/compiler.h>
  29 #include <simgear/sg_inlines.h>
  30
  31 #include <stdio.h>    //    size_t
  32 #include <string>
  33
  34 #include <simgear/constants.h>
  35 #include <simgear/debug/logstream.hxx>
  36 #include <simgear/math/sg_geodesy.hxx>
  37 #include <simgear/misc/sg_path.hxx>
  38 #include <simgear/structure/commands.hxx>
  39
  40 #include <FDM/flight.hxx>
  41
  42 #include <Aircraft/controls.hxx>
  43 #include <Main/globals.hxx>
  44 #include <Main/fg_props.hxx>
  45
  46 #include "JSBSim.hxx"
  47 #include <FDM/JSBSim/FGFDMExec.h>
  48 #include <FDM/JSBSim/FGJSBBase.h>
  49 #include <FDM/JSBSim/initialization/FGInitialCondition.h>
  50 #include <FDM/JSBSim/initialization/FGTrim.h>
  51 #include <FDM/JSBSim/models/FGModel.h>
  52 #include <FDM/JSBSim/models/FGAircraft.h>
  53 #include <FDM/JSBSim/models/FGFCS.h>
  54 #include <FDM/JSBSim/models/FGPropagate.h>
  55 #include <FDM/JSBSim/models/FGAuxiliary.h>
  56 #include <FDM/JSBSim/models/FGInertial.h>
  57 #include <FDM/JSBSim/models/FGAtmosphere.h>
  58 #include <FDM/JSBSim/models/FGMassBalance.h>
  59 #include <FDM/JSBSim/models/FGAerodynamics.h>
  60 #include <FDM/JSBSim/models/FGLGear.h>
  61 #include <FDM/JSBSim/models/FGGroundReactions.h>
  62 #include <FDM/JSBSim/models/FGPropulsion.h>
  63 #include <FDM/JSBSim/models/propulsion/FGEngine.h>
  64 #include <FDM/JSBSim/models/propulsion/FGPiston.h>
  65 #include <FDM/JSBSim/models/propulsion/FGTurbine.h>
  66 #include <FDM/JSBSim/models/propulsion/FGTurboProp.h>
  67 #include <FDM/JSBSim/models/propulsion/FGRocket.h>
  68 #include <FDM/JSBSim/models/propulsion/FGElectric.h>
  69 #include <FDM/JSBSim/models/propulsion/FGNozzle.h>
  70 #include <FDM/JSBSim/models/propulsion/FGPropeller.h>
  71 #include <FDM/JSBSim/models/propulsion/FGRotor.h>
  72 #include <FDM/JSBSim/models/propulsion/FGTank.h>
  73 #include <FDM/JSBSim/input_output/FGPropertyManager.h>
  74 #include <FDM/JSBSim/input_output/FGGroundCallback.h>
  75
  76 using namespace JSBSim;
  77
  78 static inline double
  79 FMAX (double a, double b)
  80 {
  81   return a > b ? a : b;
  82 }
  83
  84 class FGFSGroundCallback : public FGGroundCallback {
  85 public:
  86   FGFSGroundCallback(FGJSBsim* ifc) : mInterface(ifc) {}
  87   virtual ~FGFSGroundCallback() {}
  88
  89   /** Get the altitude above sea level dependent on the location. */
  90   virtual double GetAltitude(const FGLocation& l) const {
  91     double pt[3] = { SG_FEET_TO_METER*l(eX),
  92                      SG_FEET_TO_METER*l(eY),
  93                      SG_FEET_TO_METER*l(eZ) };
  94     double lat, lon, alt;
  95     sgCartToGeod( pt, &lat, &lon, &alt);
  96     return alt * SG_METER_TO_FEET;
  97   }
  98
  99   /** Compute the altitude above ground. */
 100   virtual double GetAGLevel(double t, const FGLocation& l,
 101                             FGLocation& cont, FGColumnVector3& n,
 102                             FGColumnVector3& v, FGColumnVector3& w) const {
 103     double loc_cart[3] = { l(eX), l(eY), l(eZ) };
 104     double contact[3], normal[3], vel[3], angularVel[3], agl = 0;
 105     mInterface->get_agl_ft(t, loc_cart, SG_METER_TO_FEET*2, contact, normal,
 106                            vel, angularVel, &agl);
 107     n = FGColumnVector3( normal[0], normal[1], normal[2] );
 108     v = FGColumnVector3( vel[0], vel[1], vel[2] );
 109     w = FGColumnVector3( angularVel[0], angularVel[1], angularVel[2] );
 110     cont = FGColumnVector3( contact[0], contact[1], contact[2] );
 111     return agl;
 112   }
 113 private:
 114   FGJSBsim* mInterface;
 115 };
 116
 117 // FG uses a squared normalized magnitude for turbulence
 118 // this lookup table maps fg's severity levels
 119 // none(0), light(1/3), moderate(2/3) and severe(3/3)
 120 // to the POE table indexes 0, 3, 4 and 7
 121 class FGTurbulenceSeverityTable : public FGTable {
 122 public:
 123   FGTurbulenceSeverityTable() : FGTable(4) {
 124     *this << (0.0/9.0) << 0.0;
 125     *this << (1.0/9.0) << 3.0;
 126     *this << (4.0/9.0) << 4.0;
 127     *this << (9.0/9.0) << 7.0;
 128   }
 129 };
 130
 131 /******************************************************************************/
 132 std::map<std::string,int> FGJSBsim::TURBULENCE_TYPE_NAMES;
 133
 134 static FGTurbulenceSeverityTable TurbulenceSeverityTable;
 135
 136 FGJSBsim::FGJSBsim( double dt )
 137   : FGInterface(dt), got_wire(false)
 138 {
 139     bool result;
 140     if( TURBULENCE_TYPE_NAMES.empty() ) {
 141         TURBULENCE_TYPE_NAMES["ttNone"]     = FGAtmosphere::ttNone;
 142         TURBULENCE_TYPE_NAMES["ttStandard"] = FGAtmosphere::ttStandard;
 143 //      TURBULENCE_TYPE_NAMES["ttBerndt"]   = FGAtmosphere::ttBerndt;
 144         TURBULENCE_TYPE_NAMES["ttCulp"]     = FGAtmosphere::ttCulp;
 145         TURBULENCE_TYPE_NAMES["ttMilspec"]  = FGAtmosphere::ttMilspec;
 146         TURBULENCE_TYPE_NAMES["ttTustin"]   = FGAtmosphere::ttTustin;
 147     }
 148
 149                                 // Set up the debugging level
 150                                 // FIXME: this will not respond to
 151                                 // runtime changes
 152
 153                                 // if flight is excluded, don't bother
 154     if ((logbuf::get_log_classes() & SG_FLIGHT) != 0) {
 155
 156                                 // do a rough-and-ready mapping to
 157                                 // the levels documented in FGFDMExec.h
 158         switch (logbuf::get_log_priority()) {
 159         case SG_BULK:
 160             FGJSBBase::debug_lvl = 0x1f;
 161             break;
 162         case SG_DEBUG:
 163             FGJSBBase::debug_lvl = 0x0f;
 164         case SG_INFO:
 165             FGJSBBase::debug_lvl = 0x01;
 166             break;
 167         case SG_WARN:
 168         case SG_ALERT:
 169             FGJSBBase::debug_lvl = 0x00;
 170             break;
 171         }
 172     }
 173
 174     fdmex = new FGFDMExec( (FGPropertyManager*)globals->get_props() );
 175
 176     // Register ground callback.
 177     fdmex->SetGroundCallback( new FGFSGroundCallback(this) );
 178
 179     Atmosphere      = fdmex->GetAtmosphere();
 180     FCS             = fdmex->GetFCS();
 181     MassBalance     = fdmex->GetMassBalance();
 182     Propulsion      = fdmex->GetPropulsion();
 183     Aircraft        = fdmex->GetAircraft();
 184     Propagate       = fdmex->GetPropagate();
 185     Auxiliary       = fdmex->GetAuxiliary();
 186     Inertial        = fdmex->GetInertial();
 187     Aerodynamics    = fdmex->GetAerodynamics();
 188     GroundReactions = fdmex->GetGroundReactions();
 189
 190     fgic=fdmex->GetIC();
 191     needTrim=true;
 192
 193     SGPath aircraft_path( fgGetString("/sim/aircraft-dir") );
 194
 195     SGPath engine_path( fgGetString("/sim/aircraft-dir") );
 196     engine_path.append( "Engine" );
 197
 198     SGPath systems_path( fgGetString("/sim/aircraft-dir") );
 199     systems_path.append( "Systems" );
 200
 201 // deprecate sim-time-sec for simulation/sim-time-sec
 202 // remove alias with increased configuration file version number (2.1 or later)
 203     SGPropertyNode * node = fgGetNode("/fdm/jsbsim/simulation/sim-time-sec");
 204     fgGetNode("/fdm/jsbsim/sim-time-sec", true)->alias( node );
 205 // end of sim-time-sec deprecation patch
 206
 207     fdmex->Setdt( dt );
 208
 209     result = fdmex->LoadModel( aircraft_path.str(),
 210                                engine_path.str(),
 211                                systems_path.str(),
 212                                fgGetString("/sim/aero"), false );
 213
 214     if (result) {
 215       SG_LOG( SG_FLIGHT, SG_INFO, "  loaded aero.");
 216     } else {
 217       SG_LOG( SG_FLIGHT, SG_INFO,
 218               "  aero does not exist (you may have mis-typed the name).");
 219       throw(-1);
 220     }
 221
 222     SG_LOG( SG_FLIGHT, SG_INFO, "" );
 223     SG_LOG( SG_FLIGHT, SG_INFO, "" );
 224     SG_LOG( SG_FLIGHT, SG_INFO, "After loading aero definition file ..." );
 225
 226     int Neng = Propulsion->GetNumEngines();
 227     SG_LOG( SG_FLIGHT, SG_INFO, "num engines = " << Neng );
 228
 229     if ( GroundReactions->GetNumGearUnits() <= 0 ) {
 230         SG_LOG( SG_FLIGHT, SG_ALERT, "num gear units = "
 231                 << GroundReactions->GetNumGearUnits() );
 232         SG_LOG( SG_FLIGHT, SG_ALERT, "This is a very bad thing because with 0 gear units, the ground trimming");
 233         SG_LOG( SG_FLIGHT, SG_ALERT, "routine (coming up later in the code) will core dump.");
 234         SG_LOG( SG_FLIGHT, SG_ALERT, "Halting the sim now, and hoping a solution will present itself soon!");
 235         exit(-1);
 236     }
 237
 238     init_gear();
 239
 240     // Set initial fuel levels if provided.
 241     for (unsigned int i = 0; i < Propulsion->GetNumTanks(); i++) {
 242       double d;
 243       SGPropertyNode * node = fgGetNode("/consumables/fuel/tank", i, true);
 244       FGTank* tank = Propulsion->GetTank(i);
 245
 246       d = node->getNode( "density-ppg", true )->getDoubleValue();
 247       if( d > 0.0 ) {
 248         tank->SetDensity( d );
 249       } else {
 250         node->getNode( "density-ppg", true )->setDoubleValue( SG_MAX2<double>(tank->GetDensity(), 0.1) );
 251       }
 252
 253       d = node->getNode( "level-lbs", true )->getDoubleValue();
 254       if( d > 0.0 ) {
 255         tank->SetContents( d );
 256       } else {
 257         node->getNode( "level-lbs", true )->setDoubleValue( tank->GetContents() );
 258       }
 259       /* Capacity is read-only in FGTank and can't be overwritten from FlightGear */
 260       node->getNode("capacity-gal_us", true )->setDoubleValue( tank->GetCapacityGallons() );
 261     }
 262     Propulsion->SetFuelFreeze((fgGetNode("/sim/freeze/fuel",true))->getBoolValue());
 263
 264     fgSetDouble("/fdm/trim/pitch-trim", FCS->GetPitchTrimCmd());
 265     fgSetDouble("/fdm/trim/throttle",   FCS->GetThrottleCmd(0));
 266     fgSetDouble("/fdm/trim/aileron",    FCS->GetDaCmd());
 267     fgSetDouble("/fdm/trim/rudder",     FCS->GetDrCmd());
 268
 269     startup_trim = fgGetNode("/sim/presets/trim", true);
 270
 271     trimmed = fgGetNode("/fdm/trim/trimmed", true);
 272     trimmed->setBoolValue(false);
 273
 274     pitch_trim = fgGetNode("/fdm/trim/pitch-trim", true );
 275     throttle_trim = fgGetNode("/fdm/trim/throttle", true );
 276     aileron_trim = fgGetNode("/fdm/trim/aileron", true );
 277     rudder_trim = fgGetNode("/fdm/trim/rudder", true );
 278
 279     stall_warning = fgGetNode("/sim/alarms/stall-warning",true);
 280     stall_warning->setDoubleValue(0);
 281
 282
 283     flap_pos_pct=fgGetNode("/surface-positions/flap-pos-norm",true);
 284     elevator_pos_pct=fgGetNode("/surface-positions/elevator-pos-norm",true);
 285     left_aileron_pos_pct
 286         =fgGetNode("/surface-positions/left-aileron-pos-norm",true);
 287     right_aileron_pos_pct
 288         =fgGetNode("/surface-positions/right-aileron-pos-norm",true);
 289     rudder_pos_pct=fgGetNode("/surface-positions/rudder-pos-norm",true);
 290     speedbrake_pos_pct
 291         =fgGetNode("/surface-positions/speedbrake-pos-norm",true);
 292     spoilers_pos_pct=fgGetNode("/surface-positions/spoilers-pos-norm",true);
 293     tailhook_pos_pct=fgGetNode("/gear/tailhook/position-norm",true);
 294     wing_fold_pos_pct=fgGetNode("surface-positions/wing-fold-pos-norm",true);
 295
 296     elevator_pos_pct->setDoubleValue(0);
 297     left_aileron_pos_pct->setDoubleValue(0);
 298     right_aileron_pos_pct->setDoubleValue(0);
 299     rudder_pos_pct->setDoubleValue(0);
 300     flap_pos_pct->setDoubleValue(0);
 301     speedbrake_pos_pct->setDoubleValue(0);
 302     spoilers_pos_pct->setDoubleValue(0);
 303
 304     ab_brake_engaged = fgGetNode("/autopilot/autobrake/engaged", true);
 305     ab_brake_left_pct = fgGetNode("/autopilot/autobrake/brake-left-output", true);
 306     ab_brake_right_pct = fgGetNode("/autopilot/autobrake/brake-right-output", true);
 307
 308     temperature = fgGetNode("/environment/temperature-degc",true);
 309     pressure = fgGetNode("/environment/pressure-inhg",true);
 310     density = fgGetNode("/environment/density-slugft3",true);
 311     ground_wind = fgGetNode("/environment/config/boundary/entry[0]/wind-speed-kt",true);
 312     turbulence_gain = fgGetNode("/environment/turbulence/magnitude-norm",true);
 313     turbulence_rate = fgGetNode("/environment/turbulence/rate-hz",true);
 314     turbulence_model = fgGetNode("/environment/params/jsbsim-turbulence-model",true);
 315
 316     wind_from_north= fgGetNode("/environment/wind-from-north-fps",true);
 317     wind_from_east = fgGetNode("/environment/wind-from-east-fps" ,true);
 318     wind_from_down = fgGetNode("/environment/wind-from-down-fps" ,true);
 319
 320     slaved = fgGetNode("/sim/slaved/enabled", true);
 321
 322     for (unsigned int i = 0; i < Propulsion->GetNumEngines(); i++) {
 323       SGPropertyNode * node = fgGetNode("engines/engine", i, true);
 324       Propulsion->GetEngine(i)->GetThruster()->SetRPM(node->getDoubleValue("rpm") /
 325                      Propulsion->GetEngine(i)->GetThruster()->GetGearRatio());
 326     }
 327
 328     hook_root_struct = FGColumnVector3(
 329         fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-offset-x-in", 196),
 330         fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-offset-y-in", 0),
 331         fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-offset-z-in", -16));
 332     last_hook_tip[0] = 0; last_hook_tip[1] = 0; last_hook_tip[2] = 0;
 333     last_hook_root[0] = 0; last_hook_root[1] = 0; last_hook_root[2] = 0;
 334
 335     crashed = false;
 336 }
 337
 338 /******************************************************************************/
 339 FGJSBsim::~FGJSBsim(void)
 340 {
 341   delete fdmex;
 342 }
 343
 344 /******************************************************************************/
 345
 346 // Initialize the JSBsim flight model, dt is the time increment for
 347 // each subsequent iteration through the EOM
 348
 349 void FGJSBsim::init()
 350 {
 351     SG_LOG( SG_FLIGHT, SG_INFO, "Starting and initializing JSBsim" );
 352
 353     // Explicitly call the superclass's
 354     // init method first.
 355
 356     if (fgGetBool("/environment/params/control-fdm-atmosphere")) {
 357       Atmosphere->UseExternal();
 358       Atmosphere->SetExTemperature(
 359                   9.0/5.0*(temperature->getDoubleValue()+273.15) );
 360       Atmosphere->SetExPressure(pressure->getDoubleValue()*70.726566);
 361       Atmosphere->SetExDensity(density->getDoubleValue());
 362       // initialize to no turbulence, these values get set in the update loop
 363       Atmosphere->SetTurbType(FGAtmosphere::ttNone);
 364       Atmosphere->SetTurbGain(0.0);
 365       Atmosphere->SetTurbRate(0.0);
 366       Atmosphere->SetWindspeed20ft(0.0);
 367       Atmosphere->SetProbabilityOfExceedence(0.0);
 368     } else {
 369       Atmosphere->UseInternal();
 370     }
 371
 372     fgic->SetWindNEDFpsIC( -wind_from_north->getDoubleValue(),
 373                            -wind_from_east->getDoubleValue(),
 374                            -wind_from_down->getDoubleValue() );
 375
 376     //Atmosphere->SetExTemperature(get_Static_temperature());
 377     //Atmosphere->SetExPressure(get_Static_pressure());
 378     //Atmosphere->SetExDensity(get_Density());
 379     SG_LOG(SG_FLIGHT,SG_INFO,"T,p,rho: " << fdmex->GetAtmosphere()->GetTemperature()
 380      << ", " << fdmex->GetAtmosphere()->GetPressure()
 381      << ", " << fdmex->GetAtmosphere()->GetDensity() );
 382
 383 // deprecate egt_degf for egt-degf to have consistent naming
 384 // TODO: remove this by end of 2011
 385     for (unsigned int i=0; i < Propulsion->GetNumEngines(); i++) {
 386       SGPropertyNode * node = fgGetNode("engines/engine", i, true);
 387       SGPropertyNode * egtn = node->getNode( "egt_degf" );
 388       if( egtn != NULL ) {
 389         SG_LOG(SG_FLIGHT,SG_ALERT,
 390                "Aircraft uses deprecated node egt_degf. Please upgrade to egt-degf");
 391         node->getNode("egt-degf", true)->alias( egtn );
 392       }
 393     }
 394 // end of egt_degf deprecation patch
 395
 396     FCS->SetDfPos( ofNorm, globals->get_controls()->get_flaps() );
 397
 398     common_init();
 399
 400     copy_to_JSBsim();
 401     fdmex->RunIC();     //loop JSBSim once w/o integrating
 402     if (fgGetBool("/sim/presets/running")) {
 403       Propulsion->InitRunning(-1);
 404       for (unsigned int i = 0; i < Propulsion->GetNumEngines(); i++) {
 405         FGPiston* eng = (FGPiston*)Propulsion->GetEngine(i);
 406         globals->get_controls()->set_magnetos(i, eng->GetMagnetos());
 407         globals->get_controls()->set_mixture(i, FCS->GetMixtureCmd(i));
 408       }
 409     }
 410
 411     if ( startup_trim->getBoolValue() ) {
 412       FGLocation cart(fgic->GetLongitudeRadIC(), fgic->GetLatitudeRadIC(),
 413                     fgic->GetSeaLevelRadiusFtIC() + fgic->GetAltitudeASLFtIC());
 414       double cart_pos[3], contact[3], d[3], vel[3], agl;
 415       update_ground_cache(cart, cart_pos, 0.01);
 416
 417       get_agl_ft(fdmex->GetSimTime(), cart_pos, SG_METER_TO_FEET*2, contact,
 418                  d, vel, d, &agl);
 419       double terrain_alt = sqrt(contact[0]*contact[0] + contact[1]*contact[1]
 420            + contact[2]*contact[2]) - fgic->GetSeaLevelRadiusFtIC();
 421
 422       SG_LOG(SG_FLIGHT, SG_INFO, "Ready to trim, terrain elevation is: "
 423                                  << terrain_alt * SG_METER_TO_FEET );
 424
 425       if (fgGetBool("/sim/presets/onground")) {
 426         FGColumnVector3 gndVelNED = cart.GetTec2l()
 427                                   * FGColumnVector3(vel[0], vel[1], vel[2]);
 428         fgic->SetVNorthFpsIC(gndVelNED(1));
 429         fgic->SetVEastFpsIC(gndVelNED(2));
 430         fgic->SetVDownFpsIC(gndVelNED(3));
 431       }
 432       fgic->SetTerrainElevationFtIC( terrain_alt );
 433       do_trim();
 434       needTrim = false;
 435     }
 436
 437     copy_from_JSBsim(); //update the bus
 438
 439     SG_LOG( SG_FLIGHT, SG_INFO, "  Initialized JSBSim with:" );
 440
 441     switch(fgic->GetSpeedSet()) {
 442     case setned:
 443         SG_LOG(SG_FLIGHT,SG_INFO, "  Vn,Ve,Vd= "
 444                << Propagate->GetVel(FGJSBBase::eNorth) << ", "
 445                << Propagate->GetVel(FGJSBBase::eEast) << ", "
 446                << Propagate->GetVel(FGJSBBase::eDown) << " ft/s");
 447     break;
 448     case setuvw:
 449         SG_LOG(SG_FLIGHT,SG_INFO, "  U,V,W= "
 450                << Propagate->GetUVW(1) << ", "
 451                << Propagate->GetUVW(2) << ", "
 452                << Propagate->GetUVW(3) << " ft/s");
 453     break;
 454     case setmach:
 455         SG_LOG(SG_FLIGHT,SG_INFO, "  Mach: "
 456                << Auxiliary->GetMach() );
 457     break;
 458     case setvc:
 459     default:
 460         SG_LOG(SG_FLIGHT,SG_INFO, "  Indicated Airspeed: "
 461                << Auxiliary->GetVcalibratedKTS() << " knots" );
 462     break;
 463     }
 464
 465     stall_warning->setDoubleValue(0);
 466
 467     SG_LOG( SG_FLIGHT, SG_INFO, "  Bank Angle: "
 468             << Propagate->GetEuler(FGJSBBase::ePhi)*RADTODEG << " deg" );
 469     SG_LOG( SG_FLIGHT, SG_INFO, "  Pitch Angle: "
 470             << Propagate->GetEuler(FGJSBBase::eTht)*RADTODEG << " deg" );
 471     SG_LOG( SG_FLIGHT, SG_INFO, "  True Heading: "
 472             << Propagate->GetEuler(FGJSBBase::ePsi)*RADTODEG << " deg" );
 473     SG_LOG( SG_FLIGHT, SG_INFO, "  Latitude: "
 474             << Propagate->GetLocation().GetLatitudeDeg() << " deg" );
 475     SG_LOG( SG_FLIGHT, SG_INFO, "  Longitude: "
 476             << Propagate->GetLocation().GetLongitudeDeg() << " deg" );
 477     SG_LOG( SG_FLIGHT, SG_INFO, "  Altitude: "
 478             << Propagate->GetAltitudeASL() << " feet" );
 479     SG_LOG( SG_FLIGHT, SG_INFO, "  loaded initial conditions" );
 480
 481     SG_LOG( SG_FLIGHT, SG_INFO, "  set dt" );
 482
 483     SG_LOG( SG_FLIGHT, SG_INFO, "Finished initializing JSBSim" );
 484
 485     SG_LOG( SG_FLIGHT, SG_INFO, "FGControls::get_gear_down()= " <<
 486                                   globals->get_controls()->get_gear_down() );
 487 }
 488
 489 /******************************************************************************/
 490
 491 void FGJSBsim::unbind()
 492 {
 493   fdmex->Unbind();
 494   FGInterface::unbind();
 495 }
 496
 497 /******************************************************************************/
 498
 499 // Run an iteration of the EOM (equations of motion)
 500
 501 void FGJSBsim::update( double dt )
 502 {
 503     if(crashed) {
 504       if(!fgGetBool("/sim/crashed"))
 505         fgSetBool("/sim/crashed", true);
 506       return;
 507     }
 508
 509     if (is_suspended())
 510       return;
 511
 512     int multiloop = _calc_multiloop(dt);
 513     FGLocation cart = Auxiliary->GetLocationVRP();
 514     double cart_pos[3];
 515
 516     update_ground_cache(cart, cart_pos, dt);
 517
 518     copy_to_JSBsim();
 519
 520     trimmed->setBoolValue(false);
 521
 522     for ( int i=0; i < multiloop; i++ ) {
 523       fdmex->Run();
 524       update_external_forces(fdmex->GetSimTime() + i * fdmex->GetDeltaT());
 525     }
 526
 527     FGJSBBase::Message* msg;
 528     while ((msg = fdmex->ProcessNextMessage()) != NULL) {
 529 //      msg = fdmex->ProcessNextMessage();
 530       switch (msg->type) {
 531       case FGJSBBase::Message::eText:
 532         if (msg->text == "Crash Detected: Simulation FREEZE.")
 533           crashed = true;
 534         SG_LOG( SG_FLIGHT, SG_INFO, msg->messageId << ": " << msg->text );
 535         break;
 536       case FGJSBBase::Message::eBool:
 537         SG_LOG( SG_FLIGHT, SG_INFO, msg->messageId << ": " << msg->text << " " << msg->bVal );
 538         break;
 539       case FGJSBBase::Message::eInteger:
 540         SG_LOG( SG_FLIGHT, SG_INFO, msg->messageId << ": " << msg->text << " " << msg->iVal );
 541         break;
 542       case FGJSBBase::Message::eDouble:
 543         SG_LOG( SG_FLIGHT, SG_INFO, msg->messageId << ": " << msg->text << " " << msg->dVal );
 544         break;
 545       default:
 546         SG_LOG( SG_FLIGHT, SG_INFO, "Unrecognized message type." );
 547         break;
 548       }
 549     }
 550
 551     // translate JSBsim back to FG structure so that the
 552     // autopilot (and the rest of the sim can use the updated values
 553     copy_from_JSBsim();
 554 }
 555
 556 /******************************************************************************/
 557
 558 void FGJSBsim::suspend()
 559 {
 560   fdmex->Hold();
 561   SGSubsystem::suspend();
 562 }
 563
 564 /******************************************************************************/
 565
 566 void FGJSBsim::resume()
 567 {
 568   fdmex->Resume();
 569   SGSubsystem::resume();
 570 }
 571
 572 /******************************************************************************/
 573
 574 // Convert from the FGInterface struct to the JSBsim generic_ struct
 575
 576 bool FGJSBsim::copy_to_JSBsim()
 577 {
 578     unsigned int i;
 579
 580     // copy control positions into the JSBsim structure
 581
 582     FCS->SetDaCmd( globals->get_controls()->get_aileron());
 583     FCS->SetRollTrimCmd( globals->get_controls()->get_aileron_trim() );
 584     FCS->SetDeCmd( globals->get_controls()->get_elevator());
 585     FCS->SetPitchTrimCmd( globals->get_controls()->get_elevator_trim() );
 586     FCS->SetDrCmd( -globals->get_controls()->get_rudder() );
 587     FCS->SetYawTrimCmd( -globals->get_controls()->get_rudder_trim() );
 588     FCS->SetDsCmd( globals->get_controls()->get_rudder() );
 589     FCS->SetDfCmd( globals->get_controls()->get_flaps() );
 590     FCS->SetDsbCmd( globals->get_controls()->get_speedbrake() );
 591     FCS->SetDspCmd( globals->get_controls()->get_spoilers() );
 592
 593         // Parking brake sets minimum braking
 594         // level for mains.
 595     double parking_brake = globals->get_controls()->get_brake_parking();
 596     double left_brake = globals->get_controls()->get_brake_left();
 597     double right_brake = globals->get_controls()->get_brake_right();
 598
 599     if (ab_brake_engaged->getBoolValue()) {
 600       left_brake = ab_brake_left_pct->getDoubleValue();
 601       right_brake = ab_brake_right_pct->getDoubleValue();
 602     }
 603
 604     FCS->SetLBrake(FMAX(left_brake, parking_brake));
 605     FCS->SetRBrake(FMAX(right_brake, parking_brake));
 606
 607
 608     FCS->SetCBrake( 0.0 );
 609     // FCS->SetCBrake( globals->get_controls()->get_brake(2) );
 610
 611     FCS->SetGearCmd( globals->get_controls()->get_gear_down());
 612     for (i = 0; i < Propulsion->GetNumEngines(); i++) {
 613       SGPropertyNode * node = fgGetNode("engines/engine", i, true);
 614
 615       FCS->SetThrottleCmd(i, globals->get_controls()->get_throttle(i));
 616       FCS->SetMixtureCmd(i, globals->get_controls()->get_mixture(i));
 617       FCS->SetPropAdvanceCmd(i, globals->get_controls()->get_prop_advance(i));
 618       FCS->SetFeatherCmd(i, globals->get_controls()->get_feather(i));
 619
 620       switch (Propulsion->GetEngine(i)->GetType()) {
 621       case FGEngine::etPiston:
 622         { // FGPiston code block
 623         FGPiston* eng = (FGPiston*)Propulsion->GetEngine(i);
 624         eng->SetMagnetos( globals->get_controls()->get_magnetos(i) );
 625         break;
 626         } // end FGPiston code block
 627       case FGEngine::etTurbine:
 628         { // FGTurbine code block
 629         FGTurbine* eng = (FGTurbine*)Propulsion->GetEngine(i);
 630         eng->SetAugmentation( globals->get_controls()->get_augmentation(i) );
 631         eng->SetReverse( globals->get_controls()->get_reverser(i) );
 632         //eng->SetInjection( globals->get_controls()->get_water_injection(i) );
 633         eng->SetCutoff( globals->get_controls()->get_cutoff(i) );
 634         eng->SetIgnition( globals->get_controls()->get_ignition(i) );
 635         break;
 636         } // end FGTurbine code block
 637       case FGEngine::etRocket:
 638         { // FGRocket code block
 639 //        FGRocket* eng = (FGRocket*)Propulsion->GetEngine(i);
 640         break;
 641         } // end FGRocket code block
 642       case FGEngine::etTurboprop:
 643         { // FGTurboProp code block
 644         FGTurboProp* eng = (FGTurboProp*)Propulsion->GetEngine(i);
 645         eng->SetReverse( globals->get_controls()->get_reverser(i) );
 646         eng->SetCutoff( globals->get_controls()->get_cutoff(i) );
 647         eng->SetIgnition( globals->get_controls()->get_ignition(i) );
 648
 649         eng->SetGeneratorPower( globals->get_controls()->get_generator_breaker(i) );
 650         eng->SetCondition( globals->get_controls()->get_condition(i) );
 651         break;
 652         } // end FGTurboProp code block
 653       default:
 654         break;
 655       }
 656
 657       { // FGEngine code block
 658       FGEngine* eng = Propulsion->GetEngine(i);
 659
 660       eng->SetStarter( globals->get_controls()->get_starter(i) );
 661       eng->SetRunning( node->getBoolValue("running") );
 662       } // end FGEngine code block
 663     }
 664
 665
 666     Propagate->SetSeaLevelRadius( get_Sea_level_radius() );
 667
 668     Atmosphere->SetExTemperature(
 669                   9.0/5.0*(temperature->getDoubleValue()+273.15) );
 670     Atmosphere->SetExPressure(pressure->getDoubleValue()*70.726566);
 671     Atmosphere->SetExDensity(density->getDoubleValue());
 672
 673     Atmosphere->SetTurbType((FGAtmosphere::tType)TURBULENCE_TYPE_NAMES[turbulence_model->getStringValue()]);
 674     switch( Atmosphere->GetTurbType() ) {
 675 //      case FGAtmosphere::ttBerndt:
 676         case FGAtmosphere::ttStandard:
 677         case FGAtmosphere::ttCulp: {
 678             double tmp = turbulence_gain->getDoubleValue();
 679             Atmosphere->SetTurbGain(tmp * tmp * 100.0);
 680             Atmosphere->SetTurbRate(turbulence_rate->getDoubleValue());
 681             break;
 682         }
 683         case FGAtmosphere::ttMilspec:
 684         case FGAtmosphere::ttTustin: {
 685             // milspec turbulence: 3=light, 4=moderate, 6=severe turbulence
 686             // turbulence_gain normalized: 0: none, 1/3: light, 2/3: moderate, 3/3: severe
 687             double tmp = turbulence_gain->getDoubleValue();
 688             Atmosphere->SetProbabilityOfExceedence(
 689               SGMiscd::roundToInt(TurbulenceSeverityTable.GetValue( tmp ) )
 690             );
 691             Atmosphere->SetWindspeed20ft(ground_wind->getDoubleValue());
 692             break;
 693         }
 694
 695         default:
 696             break;
 697     }
 698
 699     Atmosphere->SetWindNED( -wind_from_north->getDoubleValue(),
 700                             -wind_from_east->getDoubleValue(),
 701                             -wind_from_down->getDoubleValue() );
 702 //    SG_LOG(SG_FLIGHT,SG_INFO, "Wind NED: "
 703 //                  << get_V_north_airmass() << ", "
 704 //                  << get_V_east_airmass()  << ", "
 705 //                  << get_V_down_airmass() );
 706
 707     for (i = 0; i < Propulsion->GetNumTanks(); i++) {
 708       SGPropertyNode * node = fgGetNode("/consumables/fuel/tank", i, true);
 709       FGTank * tank = Propulsion->GetTank(i);
 710       double fuelDensity = node->getDoubleValue("density-ppg");
 711
 712       if (fuelDensity < 0.1)
 713         fuelDensity = 6.0; // Use average fuel value
 714
 715       tank->SetDensity(fuelDensity);
 716       tank->SetContents(node->getDoubleValue("level-lbs"));
 717     }
 718
 719     Propulsion->SetFuelFreeze((fgGetNode("/sim/freeze/fuel",true))->getBoolValue());
 720     fdmex->SetChild(slaved->getBoolValue());
 721
 722     return true;
 723 }
 724
 725 /******************************************************************************/
 726
 727 // Convert from the JSBsim generic_ struct to the FGInterface struct
 728
 729 bool FGJSBsim::copy_from_JSBsim()
 730 {
 731     unsigned int i, j;
 732 /*
 733     _set_Inertias( MassBalance->GetMass(),
 734                    MassBalance->GetIxx(),
 735                    MassBalance->GetIyy(),
 736                    MassBalance->GetIzz(),
 737                    MassBalance->GetIxz() );
 738 */
 739     _set_CG_Position( MassBalance->GetXYZcg(1),
 740                       MassBalance->GetXYZcg(2),
 741                       MassBalance->GetXYZcg(3) );
 742
 743     _set_Accels_Body( Aircraft->GetBodyAccel(1),
 744                       Aircraft->GetBodyAccel(2),
 745                       Aircraft->GetBodyAccel(3) );
 746
 747     _set_Accels_CG_Body_N ( Aircraft->GetNcg(1),
 748                             Aircraft->GetNcg(2),
 749                             Aircraft->GetNcg(3) );
 750
 751     _set_Accels_Pilot_Body( Auxiliary->GetPilotAccel(1),
 752                             Auxiliary->GetPilotAccel(2),
 753                             Auxiliary->GetPilotAccel(3) );
 754
 755     _set_Nlf( Aircraft->GetNlf() );
 756
 757     // Velocities
 758
 759     _set_Velocities_Local( Propagate->GetVel(FGJSBBase::eNorth),
 760                            Propagate->GetVel(FGJSBBase::eEast),
 761                            Propagate->GetVel(FGJSBBase::eDown) );
 762
 763     _set_Velocities_Wind_Body( Propagate->GetUVW(1),
 764                                Propagate->GetUVW(2),
 765                                Propagate->GetUVW(3) );
 766
 767     // Make the HUD work ...
 768     _set_Velocities_Ground( Propagate->GetVel(FGJSBBase::eNorth),
 769                             Propagate->GetVel(FGJSBBase::eEast),
 770                             -Propagate->GetVel(FGJSBBase::eDown) );
 771
 772     _set_V_rel_wind( Auxiliary->GetVt() );
 773
 774     _set_V_equiv_kts( Auxiliary->GetVequivalentKTS() );
 775
 776     _set_V_calibrated_kts( Auxiliary->GetVcalibratedKTS() );
 777
 778     _set_V_ground_speed( Auxiliary->GetVground() );
 779
 780     _set_Omega_Body( Propagate->GetPQR(FGJSBBase::eP),
 781                      Propagate->GetPQR(FGJSBBase::eQ),
 782                      Propagate->GetPQR(FGJSBBase::eR) );
 783
 784     _set_Euler_Rates( Auxiliary->GetEulerRates(FGJSBBase::ePhi),
 785                       Auxiliary->GetEulerRates(FGJSBBase::eTht),
 786                       Auxiliary->GetEulerRates(FGJSBBase::ePsi) );
 787
 788     _set_Mach_number( Auxiliary->GetMach() );
 789
 790     // Positions of Visual Reference Point
 791     FGLocation l = Auxiliary->GetLocationVRP();
 792     _updateGeocentricPosition( l.GetLatitude(), l.GetLongitude(),
 793                                l.GetRadius() - get_Sea_level_radius() );
 794
 795     _set_Altitude_AGL( Propagate->GetDistanceAGL() );
 796     {
 797       double loc_cart[3] = { l(FGJSBBase::eX), l(FGJSBBase::eY), l(FGJSBBase::eZ) };
 798       double contact[3], d[3], sd, t;
 799       is_valid_m(&t, d, &sd);
 800       get_agl_ft(t, loc_cart, SG_METER_TO_FEET*2, contact, d, d, d, &sd);
 801       double rwrad
 802         = FGColumnVector3( contact[0], contact[1], contact[2] ).Magnitude();
 803       _set_Runway_altitude( rwrad - get_Sea_level_radius() );
 804     }
 805
 806     _set_Euler_Angles( Propagate->GetEuler(FGJSBBase::ePhi),
 807                        Propagate->GetEuler(FGJSBBase::eTht),
 808                        Propagate->GetEuler(FGJSBBase::ePsi) );
 809
 810     _set_Alpha( Auxiliary->Getalpha() );
 811     _set_Beta( Auxiliary->Getbeta() );
 812
 813
 814     _set_Gamma_vert_rad( Auxiliary->GetGamma() );
 815
 816     _set_Earth_position_angle( Inertial->GetEarthPositionAngle() );
 817
 818     _set_Climb_Rate( Propagate->Gethdot() );
 819
 820     const FGMatrix33& Tl2b = Propagate->GetTl2b();
 821     for ( i = 1; i <= 3; i++ ) {
 822         for ( j = 1; j <= 3; j++ ) {
 823             _set_T_Local_to_Body( i, j, Tl2b(i,j) );
 824         }
 825     }
 826
 827     // Copy the engine values from JSBSim.
 828     for ( i=0; i < Propulsion->GetNumEngines(); i++ ) {
 829       SGPropertyNode * node = fgGetNode("engines/engine", i, true);
 830       SGPropertyNode * tnode = node->getChild("thruster", 0, true);
 831       FGThruster * thruster = Propulsion->GetEngine(i)->GetThruster();
 832
 833       switch (Propulsion->GetEngine(i)->GetType()) {
 834       case FGEngine::etPiston:
 835         { // FGPiston code block
 836         FGPiston* eng = (FGPiston*)Propulsion->GetEngine(i);
 837         node->setDoubleValue("egt-degf", eng->getExhaustGasTemp_degF());
 838         node->setDoubleValue("oil-temperature-degf", eng->getOilTemp_degF());
 839         node->setDoubleValue("oil-pressure-psi", eng->getOilPressure_psi());
 840         node->setDoubleValue("mp-osi", eng->getManifoldPressure_inHg());
 841         // NOTE: mp-osi is not in ounces per square inch.
 842         // This error is left for reasons of backwards compatibility with
 843         // existing FlightGear sound and instrument configurations.
 844         node->setDoubleValue("mp-inhg", eng->getManifoldPressure_inHg());
 845         node->setDoubleValue("cht-degf", eng->getCylinderHeadTemp_degF());
 846         node->setDoubleValue("rpm", eng->getRPM());
 847         } // end FGPiston code block
 848         break;
 849       case FGEngine::etRocket:
 850         { // FGRocket code block
 851 //        FGRocket* eng = (FGRocket*)Propulsion->GetEngine(i);
 852         } // end FGRocket code block
 853         break;
 854       case FGEngine::etTurbine:
 855         { // FGTurbine code block
 856         FGTurbine* eng = (FGTurbine*)Propulsion->GetEngine(i);
 857         node->setDoubleValue("n1", eng->GetN1());
 858         node->setDoubleValue("n2", eng->GetN2());
 859         node->setDoubleValue("egt-degf", 32 + eng->GetEGT()*9/5);
 860         node->setBoolValue("augmentation", eng->GetAugmentation());
 861         node->setBoolValue("water-injection", eng->GetInjection());
 862         node->setBoolValue("ignition", eng->GetIgnition() != 0);
 863         node->setDoubleValue("nozzle-pos-norm", eng->GetNozzle());
 864         node->setDoubleValue("inlet-pos-norm", eng->GetInlet());
 865         node->setDoubleValue("oil-pressure-psi", eng->getOilPressure_psi());
 866         node->setBoolValue("reversed", eng->GetReversed());
 867         node->setBoolValue("cutoff", eng->GetCutoff());
 868         node->setDoubleValue("epr", eng->GetEPR());
 869         globals->get_controls()->set_reverser(i, eng->GetReversed() );
 870         globals->get_controls()->set_cutoff(i, eng->GetCutoff() );
 871         globals->get_controls()->set_water_injection(i, eng->GetInjection() );
 872         globals->get_controls()->set_augmentation(i, eng->GetAugmentation() );
 873         } // end FGTurbine code block
 874         break;
 875       case FGEngine::etTurboprop:
 876         { // FGTurboProp code block
 877         FGTurboProp* eng = (FGTurboProp*)Propulsion->GetEngine(i);
 878         node->setDoubleValue("n1", eng->GetN1());
 879         //node->setDoubleValue("n2", eng->GetN2());
 880         node->setDoubleValue("itt_degf", 32 + eng->GetITT()*9/5);
 881         node->setBoolValue("ignition", eng->GetIgnition() != 0);
 882         node->setDoubleValue("nozzle-pos-norm", eng->GetNozzle());
 883         node->setDoubleValue("inlet-pos-norm", eng->GetInlet());
 884         node->setDoubleValue("oil-pressure-psi", eng->getOilPressure_psi());
 885         node->setBoolValue("reversed", eng->GetReversed());
 886         node->setBoolValue("cutoff", eng->GetCutoff());
 887         node->setBoolValue("starting", eng->GetEngStarting());
 888         node->setBoolValue("generator-power", eng->GetGeneratorPower());
 889         node->setBoolValue("damaged", eng->GetCondition() != 0);
 890         node->setBoolValue("ielu-intervent", eng->GetIeluIntervent());
 891         node->setDoubleValue("oil-temperature-degf", eng->getOilTemp_degF());
 892 //        node->setBoolValue("onfire", eng->GetFire());
 893         globals->get_controls()->set_reverser(i, eng->GetReversed() );
 894         globals->get_controls()->set_cutoff(i, eng->GetCutoff() );
 895         } // end FGTurboProp code block
 896         break;
 897       case FGEngine::etElectric:
 898         { // FGElectric code block
 899         FGElectric* eng = (FGElectric*)Propulsion->GetEngine(i);
 900         node->setDoubleValue("rpm", eng->getRPM());
 901         } // end FGElectric code block
 902         break;
 903       case FGEngine::etUnknown:
 904         break;
 905       }
 906
 907       { // FGEngine code block
 908       FGEngine* eng = Propulsion->GetEngine(i);
 909       node->setDoubleValue("fuel-flow-gph", eng->getFuelFlow_gph());
 910       node->setDoubleValue("thrust_lb", thruster->GetThrust());
 911       node->setDoubleValue("fuel-flow_pph", eng->getFuelFlow_pph());
 912       node->setBoolValue("running", eng->GetRunning());
 913       node->setBoolValue("starter", eng->GetStarter());
 914       node->setBoolValue("cranking", eng->GetCranking());
 915       globals->get_controls()->set_starter(i, eng->GetStarter() );
 916       } // end FGEngine code block
 917
 918       switch (thruster->GetType()) {
 919       case FGThruster::ttNozzle:
 920         { // FGNozzle code block
 921 //        FGNozzle* noz = (FGNozzle*)thruster;
 922         } // end FGNozzle code block
 923         break;
 924       case FGThruster::ttPropeller:
 925         { // FGPropeller code block
 926         FGPropeller* prop = (FGPropeller*)thruster;
 927         tnode->setDoubleValue("rpm", thruster->GetRPM());
 928         tnode->setDoubleValue("pitch", prop->GetPitch());
 929         tnode->setDoubleValue("torque", prop->GetTorque());
 930         tnode->setBoolValue("feathered", prop->GetFeather());
 931         } // end FGPropeller code block
 932         break;
 933       case FGThruster::ttRotor:
 934         { // FGRotor code block
 935 //        FGRotor* rotor = (FGRotor*)thruster;
 936         } // end FGRotor code block
 937         break;
 938       case FGThruster::ttDirect:
 939         { // Direct code block
 940         } // end Direct code block
 941         break;
 942       }
 943
 944     }
 945
 946     // Copy the fuel levels from JSBSim if fuel
 947     // freeze not enabled.
 948     if ( ! Propulsion->GetFuelFreeze() ) {
 949       for (i = 0; i < Propulsion->GetNumTanks(); i++) {
 950         SGPropertyNode * node = fgGetNode("/consumables/fuel/tank", i, true);
 951         FGTank* tank = Propulsion->GetTank(i);
 952         double contents = tank->GetContents();
 953         double temp = tank->GetTemperature_degC();
 954         double fuelDensity = tank->GetDensity();
 955
 956         if (fuelDensity < 0.1)
 957           fuelDensity = 6.0; // Use average fuel value
 958
 959         node->setDoubleValue("density-ppg" , fuelDensity);
 960         node->setDoubleValue("level-lbs", contents);
 961         if (temp != -9999.0) node->setDoubleValue("temperature_degC", temp);
 962       }
 963     }
 964
 965     update_gear();
 966
 967     stall_warning->setDoubleValue( Aerodynamics->GetStallWarn() );
 968
 969     elevator_pos_pct->setDoubleValue( FCS->GetDePos(ofNorm) );
 970     left_aileron_pos_pct->setDoubleValue( FCS->GetDaLPos(ofNorm) );
 971     right_aileron_pos_pct->setDoubleValue( FCS->GetDaRPos(ofNorm) );
 972     rudder_pos_pct->setDoubleValue( -1*FCS->GetDrPos(ofNorm) );
 973     flap_pos_pct->setDoubleValue( FCS->GetDfPos(ofNorm) );
 974     speedbrake_pos_pct->setDoubleValue( FCS->GetDsbPos(ofNorm) );
 975     spoilers_pos_pct->setDoubleValue( FCS->GetDspPos(ofNorm) );
 976     tailhook_pos_pct->setDoubleValue( FCS->GetTailhookPos() );
 977     wing_fold_pos_pct->setDoubleValue( FCS->GetWingFoldPos() );
 978
 979     // force a sim crashed if crashed (altitude AGL < 0)
 980     if (get_Altitude_AGL() < -100.0) {
 981          fdmex->SuspendIntegration();
 982          crashed = true;
 983     }
 984
 985     return true;
 986 }
 987
 988
 989 bool FGJSBsim::ToggleDataLogging(void)
 990 {
 991   // ToDo: handle this properly
 992   fdmex->DisableOutput();
 993   return false;
 994 }
 995
 996
 997 bool FGJSBsim::ToggleDataLogging(bool state)
 998 {
 999     if (state) {
1000       fdmex->EnableOutput();
1001       return true;
1002     } else {
1003       fdmex->DisableOutput();
1004       return false;
1005     }
1006 }
1007
1008
1009 //Positions
1010 void FGJSBsim::set_Latitude(double lat)
1011 {
1012   static SGConstPropertyNode_ptr altitude = fgGetNode("/position/altitude-ft");
1013   double alt;
1014   double sea_level_radius_meters, lat_geoc;
1015
1016   if ( altitude->getDoubleValue() > -9990 )
1017     alt = altitude->getDoubleValue();
1018   else
1019     alt = 0.0;
1020
1021   SG_LOG(SG_FLIGHT,SG_INFO,"FGJSBsim::set_Latitude: " << lat );
1022   SG_LOG(SG_FLIGHT,SG_INFO," cur alt (ft) =  " << alt );
1023
1024   sgGeodToGeoc( lat, alt * SG_FEET_TO_METER,
1025                     &sea_level_radius_meters, &lat_geoc );
1026   _set_Sea_level_radius( sea_level_radius_meters * SG_METER_TO_FEET  );
1027
1028   if (needTrim) {
1029     fgic->SetSeaLevelRadiusFtIC( sea_level_radius_meters * SG_METER_TO_FEET  );
1030     fgic->SetLatitudeRadIC( lat_geoc );
1031   }
1032   else {
1033     Propagate->SetLatitude(lat_geoc);
1034     FGInterface::set_Latitude(lat);
1035   }
1036 }
1037
1038
1039 void FGJSBsim::set_Longitude(double lon)
1040 {
1041   SG_LOG(SG_FLIGHT,SG_INFO,"FGJSBsim::set_Longitude: " << lon );
1042
1043   if (needTrim)
1044     fgic->SetLongitudeRadIC(lon);
1045   else {
1046     Propagate->SetLongitude(lon);
1047     FGInterface::set_Longitude(lon);
1048   }
1049 }
1050
1051 // Sets the altitude above sea level.
1052 void FGJSBsim::set_Altitude(double alt)
1053 {
1054   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Altitude: " << alt );
1055
1056   if (needTrim)
1057     fgic->SetAltitudeASLFtIC(alt);
1058   else {
1059     Propagate->SetAltitudeASL(alt);
1060     FGInterface::set_Altitude(alt);
1061   }
1062 }
1063
1064 void FGJSBsim::set_V_calibrated_kts(double vc)
1065 {
1066     SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_V_calibrated_kts: " <<  vc );
1067
1068   if (needTrim)
1069     fgic->SetVcalibratedKtsIC(vc);
1070   else {
1071     double mach = getMachFromVcas(vc);
1072     double temp = 1.8*(temperature->getDoubleValue()+273.15);
1073     double soundSpeed = sqrt(1.4*1716.0*temp);
1074     FGColumnVector3 vUVW = Propagate->GetUVW();
1075     vUVW.Normalize();
1076     vUVW *= mach * soundSpeed;
1077     Propagate->SetUVW(1, vUVW(1));
1078     Propagate->SetUVW(2, vUVW(2));
1079     Propagate->SetUVW(3, vUVW(3));
1080
1081     FGInterface::set_V_calibrated_kts(vc);
1082   }
1083 }
1084
1085 void FGJSBsim::set_Mach_number(double mach)
1086 {
1087   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Mach_number: " <<  mach );
1088
1089   if (needTrim)
1090     fgic->SetMachIC(mach);
1091   else {
1092     double temp = 1.8*(temperature->getDoubleValue()+273.15);
1093     double soundSpeed = sqrt(1.4*1716.0*temp);
1094     FGColumnVector3 vUVW = Propagate->GetUVW();
1095     vUVW.Normalize();
1096     vUVW *= mach * soundSpeed;
1097     Propagate->SetUVW(1, vUVW(1));
1098     Propagate->SetUVW(2, vUVW(2));
1099     Propagate->SetUVW(3, vUVW(3));
1100
1101     FGInterface::set_Mach_number(mach);
1102   }
1103 }
1104
1105 void FGJSBsim::set_Velocities_Local( double north, double east, double down )
1106 {
1107   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Velocities_Local: "
1108      << north << ", " <<  east << ", " << down );
1109
1110   if (needTrim) {
1111     fgic->SetVNorthFpsIC(north);
1112     fgic->SetVEastFpsIC(east);
1113     fgic->SetVDownFpsIC(down);
1114   }
1115   else {
1116     FGColumnVector3 vNED(north, east, down);
1117     FGColumnVector3 vUVW = Propagate->GetTl2b() * vNED;
1118     Propagate->SetUVW(1, vUVW(1));
1119     Propagate->SetUVW(2, vUVW(2));
1120     Propagate->SetUVW(3, vUVW(3));
1121
1122     FGInterface::set_Velocities_Local(north, east, down);
1123   }
1124 }
1125
1126 void FGJSBsim::set_Velocities_Wind_Body( double u, double v, double w)
1127 {
1128   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Velocities_Wind_Body: "
1129      << u << ", " <<  v << ", " <<  w );
1130
1131   if (needTrim) {
1132     fgic->SetUBodyFpsIC(u);
1133     fgic->SetVBodyFpsIC(v);
1134     fgic->SetWBodyFpsIC(w);
1135   }
1136   else {
1137     Propagate->SetUVW(1, u);
1138     Propagate->SetUVW(2, v);
1139     Propagate->SetUVW(3, w);
1140
1141     FGInterface::set_Velocities_Wind_Body(u, v, w);
1142   }
1143 }
1144
1145 //Euler angles
1146 void FGJSBsim::set_Euler_Angles( double phi, double theta, double psi )
1147 {
1148   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Euler_Angles: "
1149      << phi << ", " << theta << ", " << psi );
1150
1151   if (needTrim) {
1152     fgic->SetThetaRadIC(theta);
1153     fgic->SetPhiRadIC(phi);
1154     fgic->SetPsiRadIC(psi);
1155   }
1156   else {
1157     FGQuaternion quat(phi, theta, psi);
1158     FGMatrix33 Tl2b = quat.GetT();
1159     FGMatrix33 Ti2b = Tl2b*Propagate->GetTi2l();
1160     FGQuaternion Qi = Ti2b.GetQuaternion();
1161     Propagate->SetInertialOrientation(Qi);
1162
1163     FGInterface::set_Euler_Angles(phi, theta, psi);
1164   }
1165 }
1166
1167 //Flight Path
1168 void FGJSBsim::set_Climb_Rate( double roc)
1169 {
1170   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Climb_Rate: " << roc );
1171
1172   //since both climb rate and flight path angle are set in the FG
1173   //startup sequence, something is needed to keep one from cancelling
1174   //out the other.
1175   if( !(fabs(roc) > 1 && fabs(fgic->GetFlightPathAngleRadIC()) < 0.01) ) {
1176     if (needTrim)
1177       fgic->SetClimbRateFpsIC(roc);
1178     else {
1179       FGColumnVector3 vNED = Propagate->GetVel();
1180       vNED(FGJSBBase::eDown) = -roc;
1181       FGColumnVector3 vUVW = Propagate->GetTl2b() * vNED;
1182       Propagate->SetUVW(1, vUVW(1));
1183       Propagate->SetUVW(2, vUVW(2));
1184       Propagate->SetUVW(3, vUVW(3));
1185
1186       FGInterface::set_Climb_Rate(roc);
1187     }
1188   }
1189 }
1190
1191 void FGJSBsim::set_Gamma_vert_rad( double gamma)
1192 {
1193   SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Gamma_vert_rad: " << gamma );
1194
1195   if( !(fabs(gamma) < 0.01 && fabs(fgic->GetClimbRateFpsIC()) > 1) ) {
1196     if (needTrim)
1197       fgic->SetFlightPathAngleRadIC(gamma);
1198     else {
1199       FGColumnVector3 vNED = Propagate->GetVel();
1200       double vt = vNED.Magnitude();
1201       vNED(FGJSBBase::eDown) = -vt * sin(gamma);
1202       FGColumnVector3 vUVW = Propagate->GetTl2b() * vNED;
1203       Propagate->SetUVW(1, vUVW(1));
1204       Propagate->SetUVW(2, vUVW(2));
1205       Propagate->SetUVW(3, vUVW(3));
1206
1207       FGInterface::set_Gamma_vert_rad(gamma);
1208     }
1209   }
1210 }
1211 // Reverse the VCAS formula to obtain the corresponding Mach number. For subsonic
1212 // speeds, the reversed formula has a closed form. For supersonic speeds, the
1213 // formula is reversed by the Newton-Raphson algorithm.
1214
1215 double FGJSBsim::getMachFromVcas(double vcas)
1216 {
1217   double p=pressure->getDoubleValue();
1218   double psl=fdmex->GetAtmosphere()->GetPressureSL();
1219   double rhosl=fdmex->GetAtmosphere()->GetDensitySL();
1220
1221   double pt = p + psl*(pow(1+vcas*vcas*rhosl/(7.0*psl),3.5)-1);
1222
1223   if (pt/p < 1.89293)
1224     return sqrt(5.0*(pow(pt/p, 0.2857143) -1)); // Mach < 1
1225   else {
1226     // Mach >= 1
1227     double mach = sqrt(0.77666*pt/p); // Initial guess is based on a quadratic approximation of the Rayleigh formula
1228     double delta = 1.;
1229     double target = pt/(166.92158*p);
1230     int iter = 0;
1231
1232     // Find the root with Newton-Raphson. Since the differential is never zero,
1233     // the function is monotonic and has only one root with a multiplicity of one.
1234     // Convergence is certain.
1235     while (delta > 1E-5 && iter < 10) {
1236       double m2 = mach*mach; // Mach^2
1237       double m6 = m2*m2*m2;  // Mach^6
1238       delta = mach*m6/pow(7.0*m2-1.0,2.5) - target;
1239       double diff = 7.0*m6*(2.0*m2-1)/pow(7.0*m2-1.0,3.5); // Never zero when Mach >= 1
1240       mach -= delta/diff;
1241       iter++;
1242     }
1243
1244     return mach;
1245   }
1246 }
1247
1248 void FGJSBsim::init_gear(void )
1249 {
1250     FGGroundReactions* gr=fdmex->GetGroundReactions();
1251     int Ngear=GroundReactions->GetNumGearUnits();
1252     for (int i=0;i<Ngear;i++) {
1253       FGLGear *gear = gr->GetGearUnit(i);
1254       SGPropertyNode * node = fgGetNode("gear/gear", i, true);
1255       node->setDoubleValue("xoffset-in", gear->GetBodyLocation()(1));
1256       node->setDoubleValue("yoffset-in", gear->GetBodyLocation()(2));
1257       node->setDoubleValue("zoffset-in", gear->GetBodyLocation()(3));
1258       node->setBoolValue("wow", gear->GetWOW());
1259       node->setDoubleValue("rollspeed-ms", gear->GetWheelRollVel()*0.3043);
1260       node->setBoolValue("has-brake", gear->GetBrakeGroup() > 0);
1261       node->setDoubleValue("position-norm", gear->GetGearUnitPos());
1262       node->setDoubleValue("tire-pressure-norm", gear->GetTirePressure());
1263       node->setDoubleValue("compression-norm", gear->GetCompLen());
1264       node->setDoubleValue("compression-ft", gear->GetCompLen());
1265       if ( gear->GetSteerable() )
1266         node->setDoubleValue("steering-norm", gear->GetSteerNorm());
1267     }
1268 }
1269
1270 void FGJSBsim::update_gear(void)
1271 {
1272     FGGroundReactions* gr=fdmex->GetGroundReactions();
1273     int Ngear=GroundReactions->GetNumGearUnits();
1274     for (int i=0;i<Ngear;i++) {
1275       FGLGear *gear = gr->GetGearUnit(i);
1276       SGPropertyNode * node = fgGetNode("gear/gear", i, true);
1277       node->getChild("wow", 0, true)->setBoolValue( gear->GetWOW());
1278       node->getChild("rollspeed-ms", 0, true)->setDoubleValue(gear->GetWheelRollVel()*0.3043);
1279       node->getChild("position-norm", 0, true)->setDoubleValue(gear->GetGearUnitPos());
1280       gear->SetTirePressure(node->getDoubleValue("tire-pressure-norm"));
1281       node->setDoubleValue("compression-norm", gear->GetCompLen());
1282       node->setDoubleValue("compression-ft", gear->GetCompLen());
1283       if ( gear->GetSteerable() )
1284         node->setDoubleValue("steering-norm", gear->GetSteerNorm());
1285     }
1286 }
1287
1288 void FGJSBsim::do_trim(void)
1289 {
1290   FGTrim *fgtrim;
1291
1292   if ( fgGetBool("/sim/presets/onground") )
1293   {
1294     fgtrim = new FGTrim(fdmex,tGround);
1295   } else {
1296     fgtrim = new FGTrim(fdmex,tFull);
1297   }
1298
1299   if ( !fgtrim->DoTrim() ) {
1300     fgtrim->Report();
1301     fgtrim->TrimStats();
1302   } else {
1303     trimmed->setBoolValue(true);
1304   }
1305   delete fgtrim;
1306
1307   pitch_trim->setDoubleValue( FCS->GetPitchTrimCmd() );
1308   throttle_trim->setDoubleValue( FCS->GetThrottleCmd(0) );
1309   aileron_trim->setDoubleValue( FCS->GetDaCmd() );
1310   rudder_trim->setDoubleValue( -FCS->GetDrCmd() );
1311
1312   globals->get_controls()->set_elevator_trim(FCS->GetPitchTrimCmd());
1313   globals->get_controls()->set_elevator(FCS->GetDeCmd());
1314   for( unsigned i = 0; i < Propulsion->GetNumEngines(); i++ )
1315     globals->get_controls()->set_throttle(i, FCS->GetThrottleCmd(i));
1316
1317   globals->get_controls()->set_aileron(FCS->GetDaCmd());
1318   globals->get_controls()->set_rudder( -FCS->GetDrCmd());
1319
1320   SG_LOG( SG_FLIGHT, SG_INFO, "  Trim complete" );
1321 }
1322
1323 bool FGJSBsim::update_ground_cache(FGLocation cart, double* cart_pos, double dt)
1324 {
1325   // Compute the radius of the aircraft. That is the radius of a ball
1326   // where all gear units are in. At the moment it is at least 10ft ...
1327   double acrad = 10.0;
1328   int n_gears = GroundReactions->GetNumGearUnits();
1329   for (int i=0; i<n_gears; ++i) {
1330     FGColumnVector3 bl = GroundReactions->GetGearUnit(i)->GetBodyLocation();
1331     double r = bl.Magnitude();
1332     if (acrad < r)
1333       acrad = r;
1334   }
1335
1336   // Compute the potential movement of this aircraft and query for the
1337   // ground in this area.
1338   double groundCacheRadius = acrad + 2*dt*Propagate->GetUVW().Magnitude();
1339   cart_pos[0] = cart(1);
1340   cart_pos[1] = cart(2);
1341   cart_pos[2] = cart(3);
1342   double t0 = fdmex->GetSimTime();
1343   bool cache_ok = prepare_ground_cache_ft( t0, t0 + dt, cart_pos,
1344                                            groundCacheRadius );
1345   if (!cache_ok) {
1346     SG_LOG(SG_FLIGHT, SG_WARN,
1347            "FGInterface is being called without scenery below the aircraft!");
1348
1349     SG_LOG(SG_FLIGHT, SG_WARN, "altitude         = "
1350                       << fgic->GetAltitudeASLFtIC());
1351
1352     SG_LOG(SG_FLIGHT, SG_WARN, "sea level radius = "
1353                       << fgic->GetSeaLevelRadiusFtIC());
1354
1355     SG_LOG(SG_FLIGHT, SG_WARN, "latitude         = "
1356                       << fgic->GetLatitudeRadIC());
1357
1358     SG_LOG(SG_FLIGHT, SG_WARN, "longitude        = "
1359                       << fgic->GetLongitudeRadIC());
1360   }
1361
1362   return cache_ok;
1363 }
1364
1365 bool
1366 FGJSBsim::get_agl_ft(double t, const double pt[3], double alt_off,
1367                      double contact[3], double normal[3], double vel[3],
1368                      double angularVel[3], double *agl)
1369 {
1370    const SGMaterial* material;
1371    simgear::BVHNode::Id id;
1372    if (!FGInterface::get_agl_ft(t, pt, alt_off, contact, normal, vel,
1373                                 angularVel, material, id))
1374        return false;
1375    SGGeod geodPt = SGGeod::fromCart(SG_FEET_TO_METER*SGVec3d(pt));
1376    SGQuatd hlToEc = SGQuatd::fromLonLat(geodPt);
1377    *agl = dot(hlToEc.rotate(SGVec3d(0, 0, 1)), SGVec3d(contact) - SGVec3d(pt));
1378    return true;
1379 }
1380
1381 inline static double sqr(double x)
1382 {
1383     return x * x;
1384 }
1385
1386 static double angle_diff(double a, double b)
1387 {
1388     double diff = fabs(a - b);
1389     if (diff > 180) diff = 360 - diff;
1390
1391     return diff;
1392 }
1393
1394 static void check_hook_solution(const FGColumnVector3& ground_normal_body, double E, double hook_length, double sin_fi_guess, double cos_fi_guess, double* sin_fis, double* cos_fis, double* fis, int* points)
1395 {
1396     FGColumnVector3 tip(-hook_length * cos_fi_guess, 0, hook_length * sin_fi_guess);
1397     double dist = DotProduct(tip, ground_normal_body);
1398     if (fabs(dist + E) < 0.0001) {
1399         sin_fis[*points] = sin_fi_guess;
1400         cos_fis[*points] = cos_fi_guess;
1401         fis[*points] = atan2(sin_fi_guess, cos_fi_guess) * SG_RADIANS_TO_DEGREES;
1402         (*points)++;
1403     }
1404 }
1405
1406
1407 static void check_hook_solution(const FGColumnVector3& ground_normal_body, double E, double hook_length, double sin_fi_guess, double* sin_fis, double* cos_fis, double* fis, int* points)
1408 {
1409     if (sin_fi_guess >= -1 && sin_fi_guess <= 1) {
1410         double cos_fi_guess = sqrt(1 - sqr(sin_fi_guess));
1411         check_hook_solution(ground_normal_body, E, hook_length, sin_fi_guess, cos_fi_guess, sin_fis, cos_fis, fis, points);
1412         if (fabs(cos_fi_guess) > SG_EPSILON) {
1413             check_hook_solution(ground_normal_body, E, hook_length, sin_fi_guess, -cos_fi_guess, sin_fis, cos_fis, fis, points);
1414         }
1415     }
1416 }
1417
1418 void FGJSBsim::update_external_forces(double t_off)
1419 {
1420     const FGMatrix33& Tb2l = Propagate->GetTb2l();
1421     const FGMatrix33& Tl2b = Propagate->GetTl2b();
1422     const FGLocation& Location = Propagate->GetLocation();
1423     const FGMatrix33& Tec2l = Location.GetTec2l();
1424
1425     double hook_area[4][3];
1426
1427     FGColumnVector3 hook_root_body = MassBalance->StructuralToBody(hook_root_struct);
1428     FGColumnVector3 hook_root = Location.LocalToLocation(Tb2l *   hook_root_body);
1429     hook_area[1][0] = hook_root(1);
1430     hook_area[1][1] = hook_root(2);
1431     hook_area[1][2] = hook_root(3);
1432
1433     hook_length = fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-length-ft", 6.75);
1434     double fi_min = fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-min-deg", -18);
1435     double fi_max = fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-max-deg", 30);
1436     double fi = fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-norm") * (fi_max - fi_min) + fi_min;
1437     double cos_fi = cos(fi * SG_DEGREES_TO_RADIANS);
1438     double sin_fi = sin(fi * SG_DEGREES_TO_RADIANS);
1439
1440     FGColumnVector3 hook_tip_body = hook_root_body;
1441     hook_tip_body(1) -= hook_length * cos_fi;
1442     hook_tip_body(3) += hook_length * sin_fi;
1443
1444     double contact[3];
1445     double ground_normal[3];
1446     double ground_vel[3];
1447     double ground_angular_vel[3];
1448     double root_agl_ft;
1449
1450     if (!got_wire) {
1451         bool got = get_agl_ft(t_off, hook_area[1], 0, contact, ground_normal,
1452                               ground_vel, ground_angular_vel, &root_agl_ft);
1453         if (got && root_agl_ft > 0 && root_agl_ft < hook_length) {
1454             FGColumnVector3 ground_normal_body = Tl2b * (Tec2l * FGColumnVector3(ground_normal[0], ground_normal[1], ground_normal[2]));
1455             FGColumnVector3 contact_body = Tl2b * Location.LocationToLocal(FGColumnVector3(contact[0], contact[1], contact[2]));
1456             double D = -DotProduct(contact_body, ground_normal_body);
1457
1458             // check hook tip agl against same ground plane
1459             double hook_tip_agl_ft = DotProduct(hook_tip_body, ground_normal_body) + D;
1460             if (hook_tip_agl_ft < 0) {
1461
1462                 // hook tip: hx - l cos, hy, hz + l sin
1463                 // on ground:  - n0 l cos + n2 l sin + E = 0
1464
1465                 double E = D + DotProduct(hook_root_body, ground_normal_body);
1466
1467                 // substitue x = sin fi, cos fi = sqrt(1 - x * x)
1468                 // and rearrange to get a quadratic with coeffs:
1469                 double a = sqr(hook_length) * (sqr(ground_normal_body(1)) + sqr(ground_normal_body(3)));
1470                 double b = 2 * E * ground_normal_body(3) * hook_length;
1471                 double c = sqr(E) - sqr(ground_normal_body(1) * hook_length);
1472
1473                 double disc = sqr(b) - 4 * a * c;
1474                 if (disc >= 0) {
1475                     double delta = sqrt(disc) / (2 * a);
1476
1477                     // allow 4 solutions for safety, should never happen
1478                     double sin_fis[4];
1479                     double cos_fis[4];
1480                     double fis[4];
1481                     int points = 0;
1482
1483                     double sin_fi_guess = -b / (2 * a) - delta;
1484                     check_hook_solution(ground_normal_body, E, hook_length, sin_fi_guess, sin_fis, cos_fis, fis, &points);
1485                     check_hook_solution(ground_normal_body, E, hook_length, sin_fi_guess + 2 * delta, sin_fis, cos_fis, fis, &points);
1486
1487                     if (points == 2) {
1488                         double diff1 = angle_diff(fi, fis[0]);
1489                         double diff2 = angle_diff(fi, fis[1]);
1490                         int point = diff1 < diff2 ? 0 : 1;
1491                         fi = fis[point];
1492                         sin_fi = sin_fis[point];
1493                         cos_fi = cos_fis[point];
1494                         hook_tip_body(1) = hook_root_body(1) - hook_length * cos_fi;
1495                         hook_tip_body(3) = hook_root_body(3) + hook_length * sin_fi;
1496                     }
1497                 }
1498             }
1499         }
1500     } else {
1501         FGColumnVector3 hook_root_vel = Propagate->GetVel() + (Tb2l * (Propagate->GetPQR() *  hook_root_body));
1502         double wire_ends_ec[2][3];
1503         double wire_vel_ec[2][3];
1504         get_wire_ends_ft(t_off, wire_ends_ec, wire_vel_ec);
1505         FGColumnVector3 wire_vel_1 = Tec2l * FGColumnVector3(wire_vel_ec[0][0], wire_vel_ec[0][1], wire_vel_ec[0][2]);
1506         FGColumnVector3 wire_vel_2 = Tec2l * FGColumnVector3(wire_vel_ec[1][0], wire_vel_ec[1][1], wire_vel_ec[1][2]);
1507         FGColumnVector3 rel_vel = hook_root_vel - (wire_vel_1 + wire_vel_2) / 2;
1508         if (rel_vel.Magnitude() < 3) {
1509             got_wire = false;
1510             release_wire();
1511             fgSetDouble("/fdm/jsbsim/external_reactions/hook/magnitude", 0.0);
1512         } else {
1513             FGColumnVector3 wire_end1_body = Tl2b * Location.LocationToLocal(FGColumnVector3(wire_ends_ec[0][0], wire_ends_ec[0][1], wire_ends_ec[0][2])) - hook_root_body;
1514             FGColumnVector3 wire_end2_body = Tl2b * Location.LocationToLocal(FGColumnVector3(wire_ends_ec[1][0], wire_ends_ec[1][1], wire_ends_ec[1][2])) - hook_root_body;
1515             FGColumnVector3 force_plane_normal = wire_end1_body * wire_end2_body;
1516             force_plane_normal.Normalize();
1517             cos_fi = DotProduct(force_plane_normal, FGColumnVector3(0, 0, 1));
1518             if (cos_fi < 0) cos_fi = -cos_fi;
1519             sin_fi = sqrt(1 - sqr(cos_fi));
1520             fi = atan2(sin_fi, cos_fi) * SG_RADIANS_TO_DEGREES;
1521
1522             fgSetDouble("/fdm/jsbsim/external_reactions/hook/x", -cos_fi);
1523             fgSetDouble("/fdm/jsbsim/external_reactions/hook/y", 0);
1524             fgSetDouble("/fdm/jsbsim/external_reactions/hook/z", sin_fi);
1525             fgSetDouble("/fdm/jsbsim/external_reactions/hook/magnitude", fgGetDouble("/fdm/jsbsim/systems/hook/force"));
1526         }
1527     }
1528
1529     FGColumnVector3 hook_tip = Location.LocalToLocation(Tb2l * hook_tip_body);
1530
1531     hook_area[0][0] = hook_tip(1);
1532     hook_area[0][1] = hook_tip(2);
1533     hook_area[0][2] = hook_tip(3);
1534
1535     if (!got_wire) {
1536         // The previous positions.
1537         hook_area[2][0] = last_hook_root[0];
1538         hook_area[2][1] = last_hook_root[1];
1539         hook_area[2][2] = last_hook_root[2];
1540         hook_area[3][0] = last_hook_tip[0];
1541         hook_area[3][1] = last_hook_tip[1];
1542         hook_area[3][2] = last_hook_tip[2];
1543
1544         // Check if we caught a wire.
1545         // Returns true if we caught one.
1546         if (caught_wire_ft(t_off, hook_area)) {
1547                 got_wire = true;
1548         }
1549     }
1550
1551     // save actual position as old position ...
1552     last_hook_tip[0] = hook_area[0][0];
1553     last_hook_tip[1] = hook_area[0][1];
1554     last_hook_tip[2] = hook_area[0][2];
1555     last_hook_root[0] = hook_area[1][0];
1556     last_hook_root[1] = hook_area[1][1];
1557     last_hook_root[2] = hook_area[1][2];
1558
1559     fgSetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-deg", fi);
1560 }
1561