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     copy_from_JSBsim(); //update the bus
 411
 412     SG_LOG( SG_FLIGHT, SG_INFO, "  Initialized JSBSim with:" );
 413
 414     switch(fgic->GetSpeedSet()) {
 415     case setned:
 416         SG_LOG(SG_FLIGHT,SG_INFO, "  Vn,Ve,Vd= "
 417                << Propagate->GetVel(FGJSBBase::eNorth) << ", "
 418                << Propagate->GetVel(FGJSBBase::eEast) << ", "
 419                << Propagate->GetVel(FGJSBBase::eDown) << " ft/s");
 420     break;
 421     case setuvw:
 422         SG_LOG(SG_FLIGHT,SG_INFO, "  U,V,W= "
 423                << Propagate->GetUVW(1) << ", "
 424                << Propagate->GetUVW(2) << ", "
 425                << Propagate->GetUVW(3) << " ft/s");
 426     break;
 427     case setmach:
 428         SG_LOG(SG_FLIGHT,SG_INFO, "  Mach: "
 429                << Auxiliary->GetMach() );
 430     break;
 431     case setvc:
 432     default:
 433         SG_LOG(SG_FLIGHT,SG_INFO, "  Indicated Airspeed: "
 434                << Auxiliary->GetVcalibratedKTS() << " knots" );
 435     break;
 436     }
 437
 438     stall_warning->setDoubleValue(0);
 439
 440     SG_LOG( SG_FLIGHT, SG_INFO, "  Bank Angle: "
 441             << Propagate->GetEuler(FGJSBBase::ePhi)*RADTODEG << " deg" );
 442     SG_LOG( SG_FLIGHT, SG_INFO, "  Pitch Angle: "
 443             << Propagate->GetEuler(FGJSBBase::eTht)*RADTODEG << " deg" );
 444     SG_LOG( SG_FLIGHT, SG_INFO, "  True Heading: "
 445             << Propagate->GetEuler(FGJSBBase::ePsi)*RADTODEG << " deg" );
 446     SG_LOG( SG_FLIGHT, SG_INFO, "  Latitude: "
 447             << Propagate->GetLocation().GetLatitudeDeg() << " deg" );
 448     SG_LOG( SG_FLIGHT, SG_INFO, "  Longitude: "
 449             << Propagate->GetLocation().GetLongitudeDeg() << " deg" );
 450     SG_LOG( SG_FLIGHT, SG_INFO, "  Altitude: "
 451             << Propagate->GetAltitudeASL() << " feet" );
 452     SG_LOG( SG_FLIGHT, SG_INFO, "  loaded initial conditions" );
 453
 454     SG_LOG( SG_FLIGHT, SG_INFO, "  set dt" );
 455
 456     SG_LOG( SG_FLIGHT, SG_INFO, "Finished initializing JSBSim" );
 457
 458     SG_LOG( SG_FLIGHT, SG_INFO, "FGControls::get_gear_down()= " <<
 459                                   globals->get_controls()->get_gear_down() );
 460 }
 461
 462 /******************************************************************************/
 463
 464 void FGJSBsim::unbind()
 465 {
 466   fdmex->Unbind();
 467   FGInterface::unbind();
 468 }
 469
 470 /******************************************************************************/
 471
 472 // Run an iteration of the EOM (equations of motion)
 473
 474 void FGJSBsim::update( double dt )
 475 {
 476     if(crashed) {
 477       if(!fgGetBool("/sim/crashed"))
 478         fgSetBool("/sim/crashed", true);
 479       return;
 480     }
 481
 482     if (is_suspended())
 483       return;
 484
 485     int multiloop = _calc_multiloop(dt);
 486
 487     int i;
 488
 489     // Compute the radius of the aircraft. That is the radius of a ball
 490     // where all gear units are in. At the moment it is at least 10ft ...
 491     double acrad = 10.0;
 492     int n_gears = GroundReactions->GetNumGearUnits();
 493     for (i=0; i<n_gears; ++i) {
 494       FGColumnVector3 bl = GroundReactions->GetGearUnit(i)->GetBodyLocation();
 495       double r = bl.Magnitude();
 496       if (acrad < r)
 497         acrad = r;
 498     }
 499
 500     // Compute the potential movement of this aircraft and query for the
 501     // ground in this area.
 502     double groundCacheRadius = acrad + 2*dt*Propagate->GetUVW().Magnitude();
 503     double alt, slr, lat, lon;
 504     FGLocation cart = Auxiliary->GetLocationVRP();
 505     if ( needTrim && startup_trim->getBoolValue() ) {
 506       alt = fgic->GetAltitudeASLFtIC();
 507       slr = fgic->GetSeaLevelRadiusFtIC();
 508       lat = fgic->GetLatitudeDegIC() * SGD_DEGREES_TO_RADIANS;
 509       lon = fgic->GetLongitudeDegIC() * SGD_DEGREES_TO_RADIANS;
 510       cart = FGLocation(lon, lat, alt+slr);
 511     }
 512     double cart_pos[3] = { cart(1), cart(2), cart(3) };
 513     double t0 = fdmex->GetSimTime();
 514     bool cache_ok = prepare_ground_cache_ft( t0, t0 + dt, cart_pos,
 515                                              groundCacheRadius );
 516     if (!cache_ok) {
 517       SG_LOG(SG_FLIGHT, SG_WARN,
 518              "FGInterface is being called without scenery below the aircraft!");
 519
 520       alt = fgic->GetAltitudeASLFtIC();
 521       SG_LOG(SG_FLIGHT, SG_WARN, "altitude         = " << alt);
 522
 523       slr = fgic->GetSeaLevelRadiusFtIC();
 524       SG_LOG(SG_FLIGHT, SG_WARN, "sea level radius = " << slr);
 525
 526       lat = fgic->GetLatitudeDegIC() * SGD_DEGREES_TO_RADIANS;
 527       SG_LOG(SG_FLIGHT, SG_WARN, "latitude         = " << lat);
 528
 529       lon = fgic->GetLongitudeDegIC() * SGD_DEGREES_TO_RADIANS;
 530       SG_LOG(SG_FLIGHT, SG_WARN, "longitude        = " << lon);
 531       //return;
 532     }
 533
 534     copy_to_JSBsim();
 535
 536     trimmed->setBoolValue(false);
 537
 538     if ( needTrim ) {
 539       if ( startup_trim->getBoolValue() ) {
 540         double contact[3], d[3], vel[3], agl;
 541         get_agl_ft(fdmex->GetSimTime(), cart_pos, SG_METER_TO_FEET*2, contact,
 542                    d, vel, d, &agl);
 543         double terrain_alt = sqrt(contact[0]*contact[0] + contact[1]*contact[1]
 544              + contact[2]*contact[2]) - fgic->GetSeaLevelRadiusFtIC();
 545
 546         SG_LOG(SG_FLIGHT, SG_INFO,
 547           "Ready to trim, terrain elevation is: "
 548             << terrain_alt * SG_METER_TO_FEET );
 549
 550         if (fgGetBool("/sim/presets/onground")) {
 551           FGColumnVector3 gndVelNED = cart.GetTec2l()
 552                                     * FGColumnVector3(vel[0], vel[1], vel[2]);
 553           fgic->SetVNorthFpsIC(gndVelNED(1));
 554           fgic->SetVEastFpsIC(gndVelNED(2));
 555           fgic->SetVDownFpsIC(gndVelNED(3));
 556         }
 557         fgic->SetTerrainElevationFtIC( terrain_alt );
 558         do_trim();
 559       } else {
 560         fdmex->RunIC();  //apply any changes made through the set_ functions
 561       }
 562       needTrim = false;
 563     }
 564
 565     for ( i=0; i < multiloop; i++ ) {
 566       fdmex->Run();
 567       update_external_forces(fdmex->GetSimTime() + i * fdmex->GetDeltaT());
 568     }
 569
 570     FGJSBBase::Message* msg;
 571     while ((msg = fdmex->ProcessNextMessage()) != NULL) {
 572 //      msg = fdmex->ProcessNextMessage();
 573       switch (msg->type) {
 574       case FGJSBBase::Message::eText:
 575         if (msg->text == "Crash Detected: Simulation FREEZE.")
 576           crashed = true;
 577         SG_LOG( SG_FLIGHT, SG_INFO, msg->messageId << ": " << msg->text );
 578         break;
 579       case FGJSBBase::Message::eBool:
 580         SG_LOG( SG_FLIGHT, SG_INFO, msg->messageId << ": " << msg->text << " " << msg->bVal );
 581         break;
 582       case FGJSBBase::Message::eInteger:
 583         SG_LOG( SG_FLIGHT, SG_INFO, msg->messageId << ": " << msg->text << " " << msg->iVal );
 584         break;
 585       case FGJSBBase::Message::eDouble:
 586         SG_LOG( SG_FLIGHT, SG_INFO, msg->messageId << ": " << msg->text << " " << msg->dVal );
 587         break;
 588       default:
 589         SG_LOG( SG_FLIGHT, SG_INFO, "Unrecognized message type." );
 590         break;
 591       }
 592     }
 593
 594     // translate JSBsim back to FG structure so that the
 595     // autopilot (and the rest of the sim can use the updated values
 596     copy_from_JSBsim();
 597 }
 598
 599 /******************************************************************************/
 600
 601 void FGJSBsim::suspend()
 602 {
 603   fdmex->Hold();
 604   SGSubsystem::suspend();
 605 }
 606
 607 /******************************************************************************/
 608
 609 void FGJSBsim::resume()
 610 {
 611   fdmex->Resume();
 612   SGSubsystem::resume();
 613 }
 614
 615 /******************************************************************************/
 616
 617 // Convert from the FGInterface struct to the JSBsim generic_ struct
 618
 619 bool FGJSBsim::copy_to_JSBsim()
 620 {
 621     unsigned int i;
 622
 623     // copy control positions into the JSBsim structure
 624
 625     FCS->SetDaCmd( globals->get_controls()->get_aileron());
 626     FCS->SetRollTrimCmd( globals->get_controls()->get_aileron_trim() );
 627     FCS->SetDeCmd( globals->get_controls()->get_elevator());
 628     FCS->SetPitchTrimCmd( globals->get_controls()->get_elevator_trim() );
 629     FCS->SetDrCmd( -globals->get_controls()->get_rudder() );
 630     FCS->SetYawTrimCmd( -globals->get_controls()->get_rudder_trim() );
 631     FCS->SetDsCmd( globals->get_controls()->get_rudder() );
 632     FCS->SetDfCmd( globals->get_controls()->get_flaps() );
 633     FCS->SetDsbCmd( globals->get_controls()->get_speedbrake() );
 634     FCS->SetDspCmd( globals->get_controls()->get_spoilers() );
 635
 636         // Parking brake sets minimum braking
 637         // level for mains.
 638     double parking_brake = globals->get_controls()->get_brake_parking();
 639     double left_brake = globals->get_controls()->get_brake_left();
 640     double right_brake = globals->get_controls()->get_brake_right();
 641
 642     if (ab_brake_engaged->getBoolValue()) {
 643       left_brake = ab_brake_left_pct->getDoubleValue();
 644       right_brake = ab_brake_right_pct->getDoubleValue();
 645     }
 646
 647     FCS->SetLBrake(FMAX(left_brake, parking_brake));
 648     FCS->SetRBrake(FMAX(right_brake, parking_brake));
 649
 650
 651     FCS->SetCBrake( 0.0 );
 652     // FCS->SetCBrake( globals->get_controls()->get_brake(2) );
 653
 654     FCS->SetGearCmd( globals->get_controls()->get_gear_down());
 655     for (i = 0; i < Propulsion->GetNumEngines(); i++) {
 656       SGPropertyNode * node = fgGetNode("engines/engine", i, true);
 657
 658       FCS->SetThrottleCmd(i, globals->get_controls()->get_throttle(i));
 659       FCS->SetMixtureCmd(i, globals->get_controls()->get_mixture(i));
 660       FCS->SetPropAdvanceCmd(i, globals->get_controls()->get_prop_advance(i));
 661       FCS->SetFeatherCmd(i, globals->get_controls()->get_feather(i));
 662
 663       switch (Propulsion->GetEngine(i)->GetType()) {
 664       case FGEngine::etPiston:
 665         { // FGPiston code block
 666         FGPiston* eng = (FGPiston*)Propulsion->GetEngine(i);
 667         eng->SetMagnetos( globals->get_controls()->get_magnetos(i) );
 668         break;
 669         } // end FGPiston code block
 670       case FGEngine::etTurbine:
 671         { // FGTurbine code block
 672         FGTurbine* eng = (FGTurbine*)Propulsion->GetEngine(i);
 673         eng->SetAugmentation( globals->get_controls()->get_augmentation(i) );
 674         eng->SetReverse( globals->get_controls()->get_reverser(i) );
 675         //eng->SetInjection( globals->get_controls()->get_water_injection(i) );
 676         eng->SetCutoff( globals->get_controls()->get_cutoff(i) );
 677         eng->SetIgnition( globals->get_controls()->get_ignition(i) );
 678         break;
 679         } // end FGTurbine code block
 680       case FGEngine::etRocket:
 681         { // FGRocket code block
 682 //        FGRocket* eng = (FGRocket*)Propulsion->GetEngine(i);
 683         break;
 684         } // end FGRocket code block
 685       case FGEngine::etTurboprop:
 686         { // FGTurboProp code block
 687         FGTurboProp* eng = (FGTurboProp*)Propulsion->GetEngine(i);
 688         eng->SetReverse( globals->get_controls()->get_reverser(i) );
 689         eng->SetCutoff( globals->get_controls()->get_cutoff(i) );
 690         eng->SetIgnition( globals->get_controls()->get_ignition(i) );
 691
 692         eng->SetGeneratorPower( globals->get_controls()->get_generator_breaker(i) );
 693         eng->SetCondition( globals->get_controls()->get_condition(i) );
 694         break;
 695         } // end FGTurboProp code block
 696       default:
 697         break;
 698       }
 699
 700       { // FGEngine code block
 701       FGEngine* eng = Propulsion->GetEngine(i);
 702
 703       eng->SetStarter( globals->get_controls()->get_starter(i) );
 704       eng->SetRunning( node->getBoolValue("running") );
 705       } // end FGEngine code block
 706     }
 707
 708
 709     Propagate->SetSeaLevelRadius( get_Sea_level_radius() );
 710
 711     Atmosphere->SetExTemperature(
 712                   9.0/5.0*(temperature->getDoubleValue()+273.15) );
 713     Atmosphere->SetExPressure(pressure->getDoubleValue()*70.726566);
 714     Atmosphere->SetExDensity(density->getDoubleValue());
 715
 716     Atmosphere->SetTurbType((FGAtmosphere::tType)TURBULENCE_TYPE_NAMES[turbulence_model->getStringValue()]);
 717     switch( Atmosphere->GetTurbType() ) {
 718         case FGAtmosphere::ttStandard:
 719         case FGAtmosphere::ttCulp:
 720         case FGAtmosphere::ttBerndt: {
 721             double tmp = turbulence_gain->getDoubleValue();
 722             Atmosphere->SetTurbGain(tmp * tmp * 100.0);
 723             Atmosphere->SetTurbRate(turbulence_rate->getDoubleValue());
 724             break;
 725         }
 726         case FGAtmosphere::ttMilspec:
 727         case FGAtmosphere::ttTustin: {
 728             // milspec turbulence: 3=light, 4=moderate, 6=severe turbulence
 729             // turbulence_gain normalized: 0: none, 1/3: light, 2/3: moderate, 3/3: severe
 730             double tmp = turbulence_gain->getDoubleValue();
 731             Atmosphere->SetProbabilityOfExceedence(
 732               SGMiscd::roundToInt(TurbulenceSeverityTable.GetValue( tmp ) )
 733             );
 734             Atmosphere->SetWindspeed20ft(ground_wind->getDoubleValue());
 735             break;
 736         }
 737
 738         default:
 739             break;
 740     }
 741
 742     Atmosphere->SetWindNED( -wind_from_north->getDoubleValue(),
 743                             -wind_from_east->getDoubleValue(),
 744                             -wind_from_down->getDoubleValue() );
 745 //    SG_LOG(SG_FLIGHT,SG_INFO, "Wind NED: "
 746 //                  << get_V_north_airmass() << ", "
 747 //                  << get_V_east_airmass()  << ", "
 748 //                  << get_V_down_airmass() );
 749
 750     for (i = 0; i < Propulsion->GetNumTanks(); i++) {
 751       SGPropertyNode * node = fgGetNode("/consumables/fuel/tank", i, true);
 752       FGTank * tank = Propulsion->GetTank(i);
 753       double fuelDensity = node->getDoubleValue("density-ppg");
 754
 755       if (fuelDensity < 0.1)
 756         fuelDensity = 6.0; // Use average fuel value
 757
 758       tank->SetDensity(fuelDensity);
 759       tank->SetContents(node->getDoubleValue("level-lbs"));
 760     }
 761
 762     Propulsion->SetFuelFreeze((fgGetNode("/sim/freeze/fuel",true))->getBoolValue());
 763     fdmex->SetChild(slaved->getBoolValue());
 764
 765     return true;
 766 }
 767
 768 /******************************************************************************/
 769
 770 // Convert from the JSBsim generic_ struct to the FGInterface struct
 771
 772 bool FGJSBsim::copy_from_JSBsim()
 773 {
 774     unsigned int i, j;
 775 /*
 776     _set_Inertias( MassBalance->GetMass(),
 777                    MassBalance->GetIxx(),
 778                    MassBalance->GetIyy(),
 779                    MassBalance->GetIzz(),
 780                    MassBalance->GetIxz() );
 781 */
 782     _set_CG_Position( MassBalance->GetXYZcg(1),
 783                       MassBalance->GetXYZcg(2),
 784                       MassBalance->GetXYZcg(3) );
 785
 786     _set_Accels_Body( Aircraft->GetBodyAccel(1),
 787                       Aircraft->GetBodyAccel(2),
 788                       Aircraft->GetBodyAccel(3) );
 789
 790     _set_Accels_CG_Body_N ( Aircraft->GetNcg(1),
 791                             Aircraft->GetNcg(2),
 792                             Aircraft->GetNcg(3) );
 793
 794     _set_Accels_Pilot_Body( Auxiliary->GetPilotAccel(1),
 795                             Auxiliary->GetPilotAccel(2),
 796                             Auxiliary->GetPilotAccel(3) );
 797
 798     _set_Nlf( Aircraft->GetNlf() );
 799
 800     // Velocities
 801
 802     _set_Velocities_Local( Propagate->GetVel(FGJSBBase::eNorth),
 803                            Propagate->GetVel(FGJSBBase::eEast),
 804                            Propagate->GetVel(FGJSBBase::eDown) );
 805
 806     _set_Velocities_Wind_Body( Propagate->GetUVW(1),
 807                                Propagate->GetUVW(2),
 808                                Propagate->GetUVW(3) );
 809
 810     // Make the HUD work ...
 811     _set_Velocities_Ground( Propagate->GetVel(FGJSBBase::eNorth),
 812                             Propagate->GetVel(FGJSBBase::eEast),
 813                             -Propagate->GetVel(FGJSBBase::eDown) );
 814
 815     _set_V_rel_wind( Auxiliary->GetVt() );
 816
 817     _set_V_equiv_kts( Auxiliary->GetVequivalentKTS() );
 818
 819     _set_V_calibrated_kts( Auxiliary->GetVcalibratedKTS() );
 820
 821     _set_V_ground_speed( Auxiliary->GetVground() );
 822
 823     _set_Omega_Body( Propagate->GetPQR(FGJSBBase::eP),
 824                      Propagate->GetPQR(FGJSBBase::eQ),
 825                      Propagate->GetPQR(FGJSBBase::eR) );
 826
 827     _set_Euler_Rates( Auxiliary->GetEulerRates(FGJSBBase::ePhi),
 828                       Auxiliary->GetEulerRates(FGJSBBase::eTht),
 829                       Auxiliary->GetEulerRates(FGJSBBase::ePsi) );
 830
 831     _set_Mach_number( Auxiliary->GetMach() );
 832
 833     // Positions of Visual Reference Point
 834     FGLocation l = Auxiliary->GetLocationVRP();
 835     _updateGeocentricPosition( l.GetLatitude(), l.GetLongitude(),
 836                                l.GetRadius() - get_Sea_level_radius() );
 837
 838     _set_Altitude_AGL( Propagate->GetDistanceAGL() );
 839     {
 840       double loc_cart[3] = { l(FGJSBBase::eX), l(FGJSBBase::eY), l(FGJSBBase::eZ) };
 841       double contact[3], d[3], sd, t;
 842       is_valid_m(&t, d, &sd);
 843       get_agl_ft(t, loc_cart, SG_METER_TO_FEET*2, contact, d, d, d, &sd);
 844       double rwrad
 845         = FGColumnVector3( contact[0], contact[1], contact[2] ).Magnitude();
 846       _set_Runway_altitude( rwrad - get_Sea_level_radius() );
 847     }
 848
 849     _set_Euler_Angles( Propagate->GetEuler(FGJSBBase::ePhi),
 850                        Propagate->GetEuler(FGJSBBase::eTht),
 851                        Propagate->GetEuler(FGJSBBase::ePsi) );
 852
 853     _set_Alpha( Auxiliary->Getalpha() );
 854     _set_Beta( Auxiliary->Getbeta() );
 855
 856
 857     _set_Gamma_vert_rad( Auxiliary->GetGamma() );
 858
 859     _set_Earth_position_angle( Inertial->GetEarthPositionAngle() );
 860
 861     _set_Climb_Rate( Propagate->Gethdot() );
 862
 863     const FGMatrix33& Tl2b = Propagate->GetTl2b();
 864     for ( i = 1; i <= 3; i++ ) {
 865         for ( j = 1; j <= 3; j++ ) {
 866             _set_T_Local_to_Body( i, j, Tl2b(i,j) );
 867         }
 868     }
 869
 870     // Copy the engine values from JSBSim.
 871     for ( i=0; i < Propulsion->GetNumEngines(); i++ ) {
 872       SGPropertyNode * node = fgGetNode("engines/engine", i, true);
 873       SGPropertyNode * tnode = node->getChild("thruster", 0, true);
 874       FGThruster * thruster = Propulsion->GetEngine(i)->GetThruster();
 875
 876       switch (Propulsion->GetEngine(i)->GetType()) {
 877       case FGEngine::etPiston:
 878         { // FGPiston code block
 879         FGPiston* eng = (FGPiston*)Propulsion->GetEngine(i);
 880         node->setDoubleValue("egt-degf", eng->getExhaustGasTemp_degF());
 881         node->setDoubleValue("oil-temperature-degf", eng->getOilTemp_degF());
 882         node->setDoubleValue("oil-pressure-psi", eng->getOilPressure_psi());
 883         node->setDoubleValue("mp-osi", eng->getManifoldPressure_inHg());
 884         // NOTE: mp-osi is not in ounces per square inch.
 885         // This error is left for reasons of backwards compatibility with
 886         // existing FlightGear sound and instrument configurations.
 887         node->setDoubleValue("mp-inhg", eng->getManifoldPressure_inHg());
 888         node->setDoubleValue("cht-degf", eng->getCylinderHeadTemp_degF());
 889         node->setDoubleValue("rpm", eng->getRPM());
 890         } // end FGPiston code block
 891         break;
 892       case FGEngine::etRocket:
 893         { // FGRocket code block
 894 //        FGRocket* eng = (FGRocket*)Propulsion->GetEngine(i);
 895         } // end FGRocket code block
 896         break;
 897       case FGEngine::etTurbine:
 898         { // FGTurbine code block
 899         FGTurbine* eng = (FGTurbine*)Propulsion->GetEngine(i);
 900         node->setDoubleValue("n1", eng->GetN1());
 901         node->setDoubleValue("n2", eng->GetN2());
 902         node->setDoubleValue("egt-degf", 32 + eng->GetEGT()*9/5);
 903         node->setBoolValue("augmentation", eng->GetAugmentation());
 904         node->setBoolValue("water-injection", eng->GetInjection());
 905         node->setBoolValue("ignition", eng->GetIgnition() != 0);
 906         node->setDoubleValue("nozzle-pos-norm", eng->GetNozzle());
 907         node->setDoubleValue("inlet-pos-norm", eng->GetInlet());
 908         node->setDoubleValue("oil-pressure-psi", eng->getOilPressure_psi());
 909         node->setBoolValue("reversed", eng->GetReversed());
 910         node->setBoolValue("cutoff", eng->GetCutoff());
 911         node->setDoubleValue("epr", eng->GetEPR());
 912         globals->get_controls()->set_reverser(i, eng->GetReversed() );
 913         globals->get_controls()->set_cutoff(i, eng->GetCutoff() );
 914         globals->get_controls()->set_water_injection(i, eng->GetInjection() );
 915         globals->get_controls()->set_augmentation(i, eng->GetAugmentation() );
 916         } // end FGTurbine code block
 917         break;
 918       case FGEngine::etTurboprop:
 919         { // FGTurboProp code block
 920         FGTurboProp* eng = (FGTurboProp*)Propulsion->GetEngine(i);
 921         node->setDoubleValue("n1", eng->GetN1());
 922         //node->setDoubleValue("n2", eng->GetN2());
 923         node->setDoubleValue("itt_degf", 32 + eng->GetITT()*9/5);
 924         node->setBoolValue("ignition", eng->GetIgnition() != 0);
 925         node->setDoubleValue("nozzle-pos-norm", eng->GetNozzle());
 926         node->setDoubleValue("inlet-pos-norm", eng->GetInlet());
 927         node->setDoubleValue("oil-pressure-psi", eng->getOilPressure_psi());
 928         node->setBoolValue("reversed", eng->GetReversed());
 929         node->setBoolValue("cutoff", eng->GetCutoff());
 930         node->setBoolValue("starting", eng->GetEngStarting());
 931         node->setBoolValue("generator-power", eng->GetGeneratorPower());
 932         node->setBoolValue("damaged", eng->GetCondition() != 0);
 933         node->setBoolValue("ielu-intervent", eng->GetIeluIntervent());
 934         node->setDoubleValue("oil-temperature-degf", eng->getOilTemp_degF());
 935 //        node->setBoolValue("onfire", eng->GetFire());
 936         globals->get_controls()->set_reverser(i, eng->GetReversed() );
 937         globals->get_controls()->set_cutoff(i, eng->GetCutoff() );
 938         } // end FGTurboProp code block
 939         break;
 940       case FGEngine::etElectric:
 941         { // FGElectric code block
 942         FGElectric* eng = (FGElectric*)Propulsion->GetEngine(i);
 943         node->setDoubleValue("rpm", eng->getRPM());
 944         } // end FGElectric code block
 945         break;
 946       case FGEngine::etUnknown:
 947         break;
 948       }
 949
 950       { // FGEngine code block
 951       FGEngine* eng = Propulsion->GetEngine(i);
 952       node->setDoubleValue("fuel-flow-gph", eng->getFuelFlow_gph());
 953       node->setDoubleValue("thrust_lb", thruster->GetThrust());
 954       node->setDoubleValue("fuel-flow_pph", eng->getFuelFlow_pph());
 955       node->setBoolValue("running", eng->GetRunning());
 956       node->setBoolValue("starter", eng->GetStarter());
 957       node->setBoolValue("cranking", eng->GetCranking());
 958       globals->get_controls()->set_starter(i, eng->GetStarter() );
 959       } // end FGEngine code block
 960
 961       switch (thruster->GetType()) {
 962       case FGThruster::ttNozzle:
 963         { // FGNozzle code block
 964 //        FGNozzle* noz = (FGNozzle*)thruster;
 965         } // end FGNozzle code block
 966         break;
 967       case FGThruster::ttPropeller:
 968         { // FGPropeller code block
 969         FGPropeller* prop = (FGPropeller*)thruster;
 970         tnode->setDoubleValue("rpm", thruster->GetRPM());
 971         tnode->setDoubleValue("pitch", prop->GetPitch());
 972         tnode->setDoubleValue("torque", prop->GetTorque());
 973         tnode->setBoolValue("feathered", prop->GetFeather());
 974         } // end FGPropeller code block
 975         break;
 976       case FGThruster::ttRotor:
 977         { // FGRotor code block
 978 //        FGRotor* rotor = (FGRotor*)thruster;
 979         } // end FGRotor code block
 980         break;
 981       case FGThruster::ttDirect:
 982         { // Direct code block
 983         } // end Direct code block
 984         break;
 985       }
 986
 987     }
 988
 989     // Copy the fuel levels from JSBSim if fuel
 990     // freeze not enabled.
 991     if ( ! Propulsion->GetFuelFreeze() ) {
 992       for (i = 0; i < Propulsion->GetNumTanks(); i++) {
 993         SGPropertyNode * node = fgGetNode("/consumables/fuel/tank", i, true);
 994         FGTank* tank = Propulsion->GetTank(i);
 995         double contents = tank->GetContents();
 996         double temp = tank->GetTemperature_degC();
 997         double fuelDensity = tank->GetDensity();
 998
 999         if (fuelDensity < 0.1)
1000           fuelDensity = 6.0; // Use average fuel value
1001
1002         node->setDoubleValue("density-ppg" , fuelDensity);
1003         node->setDoubleValue("level-lbs", contents);
1004         if (temp != -9999.0) node->setDoubleValue("temperature_degC", temp);
1005       }
1006     }
1007
1008     update_gear();
1009
1010     stall_warning->setDoubleValue( Aerodynamics->GetStallWarn() );
1011
1012     elevator_pos_pct->setDoubleValue( FCS->GetDePos(ofNorm) );
1013     left_aileron_pos_pct->setDoubleValue( FCS->GetDaLPos(ofNorm) );
1014     right_aileron_pos_pct->setDoubleValue( FCS->GetDaRPos(ofNorm) );
1015     rudder_pos_pct->setDoubleValue( -1*FCS->GetDrPos(ofNorm) );
1016     flap_pos_pct->setDoubleValue( FCS->GetDfPos(ofNorm) );
1017     speedbrake_pos_pct->setDoubleValue( FCS->GetDsbPos(ofNorm) );
1018     spoilers_pos_pct->setDoubleValue( FCS->GetDspPos(ofNorm) );
1019     tailhook_pos_pct->setDoubleValue( FCS->GetTailhookPos() );
1020     wing_fold_pos_pct->setDoubleValue( FCS->GetWingFoldPos() );
1021
1022     // force a sim crashed if crashed (altitude AGL < 0)
1023     if (get_Altitude_AGL() < -100.0) {
1024          fdmex->SuspendIntegration();
1025          crashed = true;
1026     }
1027
1028     return true;
1029 }
1030
1031
1032 bool FGJSBsim::ToggleDataLogging(void)
1033 {
1034   // ToDo: handle this properly
1035   fdmex->DisableOutput();
1036   return false;
1037 }
1038
1039
1040 bool FGJSBsim::ToggleDataLogging(bool state)
1041 {
1042     if (state) {
1043       fdmex->EnableOutput();
1044       return true;
1045     } else {
1046       fdmex->DisableOutput();
1047       return false;
1048     }
1049 }
1050
1051
1052 //Positions
1053 void FGJSBsim::set_Latitude(double lat)
1054 {
1055     static SGConstPropertyNode_ptr altitude = fgGetNode("/position/altitude-ft");
1056     double alt;
1057     double sea_level_radius_meters, lat_geoc;
1058
1059     // In case we're not trimming
1060     FGInterface::set_Latitude(lat);
1061
1062     if ( altitude->getDoubleValue() > -9990 ) {
1063       alt = altitude->getDoubleValue();
1064     } else {
1065       alt = 0.0;
1066     }
1067
1068     update_ic();
1069     SG_LOG(SG_FLIGHT,SG_INFO,"FGJSBsim::set_Latitude: " << lat );
1070     SG_LOG(SG_FLIGHT,SG_INFO," cur alt (ft) =  " << alt );
1071
1072     sgGeodToGeoc( lat, alt * SG_FEET_TO_METER,
1073                       &sea_level_radius_meters, &lat_geoc );
1074     _set_Sea_level_radius( sea_level_radius_meters * SG_METER_TO_FEET  );
1075     fgic->SetSeaLevelRadiusFtIC( sea_level_radius_meters * SG_METER_TO_FEET  );
1076     fgic->SetLatitudeRadIC( lat_geoc );
1077
1078     if (!fdmex->Holding())
1079       needTrim=true;
1080 }
1081
1082
1083 void FGJSBsim::set_Longitude(double lon)
1084 {
1085     SG_LOG(SG_FLIGHT,SG_INFO,"FGJSBsim::set_Longitude: " << lon );
1086
1087     // In case we're not trimming
1088     FGInterface::set_Longitude(lon);
1089
1090     update_ic();
1091     fgic->SetLongitudeRadIC( lon );
1092
1093     if (!fdmex->Holding())
1094       needTrim=true;
1095 }
1096
1097 // Sets the altitude above sea level.
1098 void FGJSBsim::set_Altitude(double alt)
1099 {
1100     static SGConstPropertyNode_ptr latitude = fgGetNode("/position/latitude-deg");
1101
1102     double sea_level_radius_meters,lat_geoc;
1103
1104     SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Altitude: " << alt );
1105     SG_LOG(SG_FLIGHT,SG_INFO, "  lat (deg) = " << latitude->getDoubleValue() );
1106
1107     // In case we're not trimming
1108     FGInterface::set_Altitude(alt);
1109
1110     update_ic();
1111     sgGeodToGeoc( latitude->getDoubleValue() * SGD_DEGREES_TO_RADIANS, alt,
1112                   &sea_level_radius_meters, &lat_geoc);
1113     _set_Sea_level_radius( sea_level_radius_meters * SG_METER_TO_FEET  );
1114     fgic->SetSeaLevelRadiusFtIC( sea_level_radius_meters * SG_METER_TO_FEET );
1115     SG_LOG(SG_FLIGHT, SG_INFO,
1116           "Terrain elevation: " << FGInterface::get_Runway_altitude() * SG_METER_TO_FEET );
1117     fgic->SetLatitudeRadIC( lat_geoc );
1118     fgic->SetAltitudeASLFtIC(alt);
1119
1120     if (!fdmex->Holding())
1121       needTrim=true;
1122 }
1123
1124 void FGJSBsim::set_V_calibrated_kts(double vc)
1125 {
1126     SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_V_calibrated_kts: " <<  vc );
1127
1128     // In case we're not trimming
1129     FGInterface::set_V_calibrated_kts(vc);
1130
1131     update_ic();
1132     fgic->SetVcalibratedKtsIC(vc);
1133
1134     if (!fdmex->Holding())
1135       needTrim=true;
1136 }
1137
1138 void FGJSBsim::set_Mach_number(double mach)
1139 {
1140     SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Mach_number: " <<  mach );
1141
1142     // In case we're not trimming
1143     FGInterface::set_Mach_number(mach);
1144
1145     update_ic();
1146     fgic->SetMachIC(mach);
1147
1148     if (!fdmex->Holding())
1149       needTrim=true;
1150 }
1151
1152 void FGJSBsim::set_Velocities_Local( double north, double east, double down )
1153 {
1154     SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Velocities_Local: "
1155        << north << ", " <<  east << ", " << down );
1156
1157     // In case we're not trimming
1158     FGInterface::set_Velocities_Local(north, east, down);
1159
1160     update_ic();
1161     fgic->SetVNorthFpsIC(north);
1162     fgic->SetVEastFpsIC(east);
1163     fgic->SetVDownFpsIC(down);
1164
1165     if (!fdmex->Holding())
1166       needTrim=true;
1167 }
1168
1169 void FGJSBsim::set_Velocities_Wind_Body( double u, double v, double w)
1170 {
1171     SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Velocities_Wind_Body: "
1172        << u << ", " <<  v << ", " <<  w );
1173
1174     // In case we're not trimming
1175     FGInterface::set_Velocities_Wind_Body(u, v, w);
1176
1177     update_ic();
1178     fgic->SetUBodyFpsIC(u);
1179     fgic->SetVBodyFpsIC(v);
1180     fgic->SetWBodyFpsIC(w);
1181
1182     if (!fdmex->Holding())
1183       needTrim=true;
1184 }
1185
1186 //Euler angles
1187 void FGJSBsim::set_Euler_Angles( double phi, double theta, double psi )
1188 {
1189     SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Euler_Angles: "
1190        << phi << ", " << theta << ", " << psi );
1191
1192     // In case we're not trimming
1193     FGInterface::set_Euler_Angles(phi, theta, psi);
1194
1195     update_ic();
1196     fgic->SetThetaRadIC(theta);
1197     fgic->SetPhiRadIC(phi);
1198     fgic->SetPsiRadIC(psi);
1199
1200     if (!fdmex->Holding())
1201       needTrim=true;
1202 }
1203
1204 //Flight Path
1205 void FGJSBsim::set_Climb_Rate( double roc)
1206 {
1207     SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Climb_Rate: " << roc );
1208
1209     // In case we're not trimming
1210     FGInterface::set_Climb_Rate(roc);
1211
1212     update_ic();
1213     //since both climb rate and flight path angle are set in the FG
1214     //startup sequence, something is needed to keep one from cancelling
1215     //out the other.
1216     if( !(fabs(roc) > 1 && fabs(fgic->GetFlightPathAngleRadIC()) < 0.01) ) {
1217       fgic->SetClimbRateFpsIC(roc);
1218     }
1219
1220     if (!fdmex->Holding())
1221       needTrim=true;
1222 }
1223
1224 void FGJSBsim::set_Gamma_vert_rad( double gamma)
1225 {
1226     SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Gamma_vert_rad: " << gamma );
1227
1228     update_ic();
1229     if( !(fabs(gamma) < 0.01 && fabs(fgic->GetClimbRateFpsIC()) > 1) ) {
1230       fgic->SetFlightPathAngleRadIC(gamma);
1231     }
1232
1233     if (!fdmex->Holding())
1234       needTrim=true;
1235 }
1236
1237 void FGJSBsim::init_gear(void )
1238 {
1239     FGGroundReactions* gr=fdmex->GetGroundReactions();
1240     int Ngear=GroundReactions->GetNumGearUnits();
1241     for (int i=0;i<Ngear;i++) {
1242       FGLGear *gear = gr->GetGearUnit(i);
1243       SGPropertyNode * node = fgGetNode("gear/gear", i, true);
1244       node->setDoubleValue("xoffset-in", gear->GetBodyLocation()(1));
1245       node->setDoubleValue("yoffset-in", gear->GetBodyLocation()(2));
1246       node->setDoubleValue("zoffset-in", gear->GetBodyLocation()(3));
1247       node->setBoolValue("wow", gear->GetWOW());
1248       node->setDoubleValue("rollspeed-ms", gear->GetWheelRollVel()*0.3043);
1249       node->setBoolValue("has-brake", gear->GetBrakeGroup() > 0);
1250       node->setDoubleValue("position-norm", gear->GetGearUnitPos());
1251       node->setDoubleValue("tire-pressure-norm", gear->GetTirePressure());
1252       node->setDoubleValue("compression-norm", gear->GetCompLen());
1253       node->setDoubleValue("compression-ft", gear->GetCompLen());
1254       if ( gear->GetSteerable() )
1255         node->setDoubleValue("steering-norm", gear->GetSteerNorm());
1256     }
1257 }
1258
1259 void FGJSBsim::update_gear(void)
1260 {
1261     FGGroundReactions* gr=fdmex->GetGroundReactions();
1262     int Ngear=GroundReactions->GetNumGearUnits();
1263     for (int i=0;i<Ngear;i++) {
1264       FGLGear *gear = gr->GetGearUnit(i);
1265       SGPropertyNode * node = fgGetNode("gear/gear", i, true);
1266       node->getChild("wow", 0, true)->setBoolValue( gear->GetWOW());
1267       node->getChild("rollspeed-ms", 0, true)->setDoubleValue(gear->GetWheelRollVel()*0.3043);
1268       node->getChild("position-norm", 0, true)->setDoubleValue(gear->GetGearUnitPos());
1269       gear->SetTirePressure(node->getDoubleValue("tire-pressure-norm"));
1270       node->setDoubleValue("compression-norm", gear->GetCompLen());
1271       node->setDoubleValue("compression-ft", gear->GetCompLen());
1272       if ( gear->GetSteerable() )
1273         node->setDoubleValue("steering-norm", gear->GetSteerNorm());
1274     }
1275 }
1276
1277 void FGJSBsim::do_trim(void)
1278 {
1279   FGTrim *fgtrim;
1280
1281   if ( fgGetBool("/sim/presets/onground") )
1282   {
1283     fgtrim = new FGTrim(fdmex,tGround);
1284   } else {
1285     fgtrim = new FGTrim(fdmex,tFull);
1286   }
1287
1288   if ( !fgtrim->DoTrim() ) {
1289     fgtrim->Report();
1290     fgtrim->TrimStats();
1291   } else {
1292     trimmed->setBoolValue(true);
1293   }
1294   delete fgtrim;
1295
1296   pitch_trim->setDoubleValue( FCS->GetPitchTrimCmd() );
1297   throttle_trim->setDoubleValue( FCS->GetThrottleCmd(0) );
1298   aileron_trim->setDoubleValue( FCS->GetDaCmd() );
1299   rudder_trim->setDoubleValue( -FCS->GetDrCmd() );
1300
1301   globals->get_controls()->set_elevator_trim(FCS->GetPitchTrimCmd());
1302   globals->get_controls()->set_elevator(FCS->GetDeCmd());
1303   for( unsigned i = 0; i < Propulsion->GetNumEngines(); i++ )
1304     globals->get_controls()->set_throttle(i, FCS->GetThrottleCmd(i));
1305
1306   globals->get_controls()->set_aileron(FCS->GetDaCmd());
1307   globals->get_controls()->set_rudder( -FCS->GetDrCmd());
1308
1309   SG_LOG( SG_FLIGHT, SG_INFO, "  Trim complete" );
1310 }
1311
1312 void FGJSBsim::update_ic(void)
1313 {
1314    if ( !needTrim ) {
1315      fgic->SetLatitudeRadIC(get_Lat_geocentric() );
1316      fgic->SetLongitudeRadIC( get_Longitude() );
1317      fgic->SetAltitudeASLFtIC( get_Altitude() );
1318      fgic->SetVcalibratedKtsIC( get_V_calibrated_kts() );
1319      fgic->SetThetaRadIC( get_Theta() );
1320      fgic->SetPhiRadIC( get_Phi() );
1321      fgic->SetPsiRadIC( get_Psi() );
1322      fgic->SetClimbRateFpsIC( get_Climb_Rate() );
1323    }
1324 }
1325
1326 bool
1327 FGJSBsim::get_agl_ft(double t, const double pt[3], double alt_off,
1328                      double contact[3], double normal[3], double vel[3],
1329                      double angularVel[3], double *agl)
1330 {
1331    const SGMaterial* material;
1332    simgear::BVHNode::Id id;
1333    if (!FGInterface::get_agl_ft(t, pt, alt_off, contact, normal, vel,
1334                                 angularVel, material, id))
1335        return false;
1336    SGGeod geodPt = SGGeod::fromCart(SG_FEET_TO_METER*SGVec3d(pt));
1337    SGQuatd hlToEc = SGQuatd::fromLonLat(geodPt);
1338    *agl = dot(hlToEc.rotate(SGVec3d(0, 0, 1)), SGVec3d(contact) - SGVec3d(pt));
1339    return true;
1340 }
1341
1342 inline static double dot3(const FGColumnVector3& a, const FGColumnVector3& b)
1343 {
1344     return a(1) * b(1) + a(2) * b(2) + a(3) * b(3);
1345 }
1346
1347 inline static double sqr(double x)
1348 {
1349     return x * x;
1350 }
1351
1352 static double angle_diff(double a, double b)
1353 {
1354     double diff = fabs(a - b);
1355     if (diff > 180) diff = 360 - diff;
1356
1357     return diff;
1358 }
1359
1360 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)
1361 {
1362     FGColumnVector3 tip(-hook_length * cos_fi_guess, 0, hook_length * sin_fi_guess);
1363     double dist = dot3(tip, ground_normal_body);
1364     if (fabs(dist + E) < 0.0001) {
1365         sin_fis[*points] = sin_fi_guess;
1366         cos_fis[*points] = cos_fi_guess;
1367         fis[*points] = atan2(sin_fi_guess, cos_fi_guess) * SG_RADIANS_TO_DEGREES;
1368         (*points)++;
1369     }
1370 }
1371
1372
1373 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)
1374 {
1375     if (sin_fi_guess >= -1 && sin_fi_guess <= 1) {
1376         double cos_fi_guess = sqrt(1 - sqr(sin_fi_guess));
1377         check_hook_solution(ground_normal_body, E, hook_length, sin_fi_guess, cos_fi_guess, sin_fis, cos_fis, fis, points);
1378         if (fabs(cos_fi_guess) > SG_EPSILON) {
1379             check_hook_solution(ground_normal_body, E, hook_length, sin_fi_guess, -cos_fi_guess, sin_fis, cos_fis, fis, points);
1380         }
1381     }
1382 }
1383
1384 void FGJSBsim::update_external_forces(double t_off)
1385 {
1386     const FGMatrix33& Tb2l = Propagate->GetTb2l();
1387     const FGMatrix33& Tl2b = Propagate->GetTl2b();
1388     const FGLocation& Location = Propagate->GetLocation();
1389     const FGMatrix33& Tec2l = Location.GetTec2l();
1390
1391     double hook_area[4][3];
1392
1393     FGColumnVector3 hook_root_body = MassBalance->StructuralToBody(hook_root_struct);
1394     FGColumnVector3 hook_root = Location.LocalToLocation(Tb2l *   hook_root_body);
1395     hook_area[1][0] = hook_root(1);
1396     hook_area[1][1] = hook_root(2);
1397     hook_area[1][2] = hook_root(3);
1398
1399     hook_length = fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-length-ft", 6.75);
1400     double fi_min = fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-min-deg", -18);
1401     double fi_max = fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-max-deg", 30);
1402     double fi = fgGetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-norm") * (fi_max - fi_min) + fi_min;
1403     double cos_fi = cos(fi * SG_DEGREES_TO_RADIANS);
1404     double sin_fi = sin(fi * SG_DEGREES_TO_RADIANS);
1405
1406     FGColumnVector3 hook_tip_body = hook_root_body;
1407     hook_tip_body(1) -= hook_length * cos_fi;
1408     hook_tip_body(3) += hook_length * sin_fi;
1409
1410     double contact[3];
1411     double ground_normal[3];
1412     double ground_vel[3];
1413     double ground_angular_vel[3];
1414     double root_agl_ft;
1415
1416     if (!got_wire) {
1417         bool got = get_agl_ft(t_off, hook_area[1], 0, contact, ground_normal,
1418                               ground_vel, ground_angular_vel, &root_agl_ft);
1419         if (got && root_agl_ft > 0 && root_agl_ft < hook_length) {
1420             FGColumnVector3 ground_normal_body = Tl2b * (Tec2l * FGColumnVector3(ground_normal[0], ground_normal[1], ground_normal[2]));
1421             FGColumnVector3 contact_body = Tl2b * Location.LocationToLocal(FGColumnVector3(contact[0], contact[1], contact[2]));
1422             double D = -dot3(contact_body, ground_normal_body);
1423
1424             // check hook tip agl against same ground plane
1425             double hook_tip_agl_ft = dot3(hook_tip_body, ground_normal_body) + D;
1426             if (hook_tip_agl_ft < 0) {
1427
1428                 // hook tip: hx - l cos, hy, hz + l sin
1429                 // on ground:  - n0 l cos + n2 l sin + E = 0
1430
1431                 double E = D + dot3(hook_root_body, ground_normal_body);
1432
1433                 // substitue x = sin fi, cos fi = sqrt(1 - x * x)
1434                 // and rearrange to get a quadratic with coeffs:
1435                 double a = sqr(hook_length) * (sqr(ground_normal_body(1)) + sqr(ground_normal_body(3)));
1436                 double b = 2 * E * ground_normal_body(3) * hook_length;
1437                 double c = sqr(E) - sqr(ground_normal_body(1) * hook_length);
1438
1439                 double disc = sqr(b) - 4 * a * c;
1440                 if (disc >= 0) {
1441                     double delta = sqrt(disc) / (2 * a);
1442
1443                     // allow 4 solutions for safety, should never happen
1444                     double sin_fis[4];
1445                     double cos_fis[4];
1446                     double fis[4];
1447                     int points = 0;
1448
1449                     double sin_fi_guess = -b / (2 * a) - delta;
1450                     check_hook_solution(ground_normal_body, E, hook_length, sin_fi_guess, sin_fis, cos_fis, fis, &points);
1451                     check_hook_solution(ground_normal_body, E, hook_length, sin_fi_guess + 2 * delta, sin_fis, cos_fis, fis, &points);
1452
1453                     if (points == 2) {
1454                         double diff1 = angle_diff(fi, fis[0]);
1455                         double diff2 = angle_diff(fi, fis[1]);
1456                         int point = diff1 < diff2 ? 0 : 1;
1457                         fi = fis[point];
1458                         sin_fi = sin_fis[point];
1459                         cos_fi = cos_fis[point];
1460                         hook_tip_body(1) = hook_root_body(1) - hook_length * cos_fi;
1461                         hook_tip_body(3) = hook_root_body(3) + hook_length * sin_fi;
1462                     }
1463                 }
1464             }
1465         }
1466     } else {
1467         FGColumnVector3 hook_root_vel = Propagate->GetVel() + (Tb2l * (Propagate->GetPQR() *  hook_root_body));
1468         double wire_ends_ec[2][3];
1469         double wire_vel_ec[2][3];
1470         get_wire_ends_ft(t_off, wire_ends_ec, wire_vel_ec);
1471         FGColumnVector3 wire_vel_1 = Tec2l * FGColumnVector3(wire_vel_ec[0][0], wire_vel_ec[0][1], wire_vel_ec[0][2]);
1472         FGColumnVector3 wire_vel_2 = Tec2l * FGColumnVector3(wire_vel_ec[1][0], wire_vel_ec[1][1], wire_vel_ec[1][2]);
1473         FGColumnVector3 rel_vel = hook_root_vel - (wire_vel_1 + wire_vel_2) / 2;
1474         if (rel_vel.Magnitude() < 3) {
1475             got_wire = false;
1476             release_wire();
1477             fgSetDouble("/fdm/jsbsim/external_reactions/hook/magnitude", 0.0);
1478         } else {
1479             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;
1480             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;
1481             FGColumnVector3 force_plane_normal = wire_end1_body * wire_end2_body;
1482             force_plane_normal.Normalize();
1483             cos_fi = dot3(force_plane_normal, FGColumnVector3(0, 0, 1));
1484             if (cos_fi < 0) cos_fi = -cos_fi;
1485             sin_fi = sqrt(1 - sqr(cos_fi));
1486             fi = atan2(sin_fi, cos_fi) * SG_RADIANS_TO_DEGREES;
1487
1488             fgSetDouble("/fdm/jsbsim/external_reactions/hook/x", -cos_fi);
1489             fgSetDouble("/fdm/jsbsim/external_reactions/hook/y", 0);
1490             fgSetDouble("/fdm/jsbsim/external_reactions/hook/z", sin_fi);
1491             fgSetDouble("/fdm/jsbsim/external_reactions/hook/magnitude", fgGetDouble("/fdm/jsbsim/systems/hook/force"));
1492         }
1493     }
1494
1495     FGColumnVector3 hook_tip = Location.LocalToLocation(Tb2l * hook_tip_body);
1496
1497     hook_area[0][0] = hook_tip(1);
1498     hook_area[0][1] = hook_tip(2);
1499     hook_area[0][2] = hook_tip(3);
1500
1501     if (!got_wire) {
1502         // The previous positions.
1503         hook_area[2][0] = last_hook_root[0];
1504         hook_area[2][1] = last_hook_root[1];
1505         hook_area[2][2] = last_hook_root[2];
1506         hook_area[3][0] = last_hook_tip[0];
1507         hook_area[3][1] = last_hook_tip[1];
1508         hook_area[3][2] = last_hook_tip[2];
1509
1510         // Check if we caught a wire.
1511         // Returns true if we caught one.
1512         if (caught_wire_ft(t_off, hook_area)) {
1513                 got_wire = true;
1514         }
1515     }
1516
1517     // save actual position as old position ...
1518     last_hook_tip[0] = hook_area[0][0];
1519     last_hook_tip[1] = hook_area[0][1];
1520     last_hook_tip[2] = hook_area[0][2];
1521     last_hook_root[0] = hook_area[1][0];
1522     last_hook_root[1] = hook_area[1][1];
1523     last_hook_root[2] = hook_area[1][2];
1524
1525     fgSetDouble("/fdm/jsbsim/systems/hook/tailhook-pos-deg", fi);
1526 }
1527