src/FDM/YASim/FGFDM.cpp

   1 #ifdef HAVE_CONFIG_H
   2 #  include "config.h"
   3 #endif
   4
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7
   8 #include <Main/fg_props.hxx>
   9
  10 #include "Math.hpp"
  11 #include "Jet.hpp"
  12 #include "SimpleJet.hpp"
  13 #include "Gear.hpp"
  14 #include "Hook.hpp"
  15 #include "Launchbar.hpp"
  16 #include "Atmosphere.hpp"
  17 #include "PropEngine.hpp"
  18 #include "Propeller.hpp"
  19 #include "PistonEngine.hpp"
  20 #include "TurbineEngine.hpp"
  21 #include "Rotor.hpp"
  22 #include "Rotorpart.hpp"
  23 #include "Hitch.hpp"
  24
  25 #include "FGFDM.hpp"
  26
  27 namespace yasim {
  28
  29 // Some conversion factors
  30 static const float KTS2MPS = 0.514444444444;
  31 static const float FT2M = 0.3048;
  32 static const float DEG2RAD = 0.0174532925199;
  33 static const float RPM2RAD = 0.10471975512;
  34 static const float LBS2N = 4.44822;
  35 static const float LBS2KG = 0.45359237;
  36 static const float KG2LBS = 2.2046225;
  37 static const float CM2GALS = 264.172037284;
  38 static const float HP2W = 745.700;
  39 static const float INHG2PA = 3386.389;
  40 static const float K2DEGF = 1.8;
  41 static const float K2DEGFOFFSET = -459.4;
  42 static const float CIN2CM = 1.6387064e-5;
  43 static const float YASIM_PI = 3.14159265358979323846;
  44
  45 static const float NM2FTLB = (1/(LBS2N*FT2M));
  46
  47 // Stubs, so that this can be compiled without the FlightGear
  48 // binary.  What's the best way to handle this?
  49
  50 //     float fgGetFloat(char* name, float def) { return 0; }
  51 //     void fgSetFloat(char* name, float val) {}
  52
  53 FGFDM::FGFDM()
  54 {
  55     _vehicle_radius = 0.0f;
  56
  57     _nextEngine = 0;
  58
  59     // Map /controls/flight/elevator to the approach elevator control.  This
  60     // should probably be settable, but there are very few aircraft
  61     // who trim their approaches using things other than elevator.
  62     _airplane.setElevatorControl(parseAxis("/controls/flight/elevator-trim"));
  63
  64     // FIXME: read seed from somewhere?
  65     int seed = 0;
  66     _turb = new Turbulence(10, seed);
  67 }
  68
  69 FGFDM::~FGFDM()
  70 {
  71     int i;
  72     for(i=0; i<_axes.size(); i++) {
  73         AxisRec* a = (AxisRec*)_axes.get(i);
  74         delete[] a->name;
  75         delete a;
  76     }
  77     for(i=0; i<_thrusters.size(); i++) {
  78         EngRec* er = (EngRec*)_thrusters.get(i);
  79         delete[] er->prefix;
  80         delete er->eng;
  81         delete er;
  82     }
  83     for(i=0; i<_weights.size(); i++) {
  84         WeightRec* wr = (WeightRec*)_weights.get(i);
  85         delete[] wr->prop;
  86         delete wr;
  87     }
  88     for(i=0; i<_controlProps.size(); i++)
  89         delete (PropOut*)_controlProps.get(i);
  90     delete _turb;
  91 }
  92
  93 void FGFDM::iterate(float dt)
  94 {
  95     getExternalInput(dt);
  96     _airplane.iterate(dt);
  97
  98     // Do fuel stuff (FIXME: should stash SGPropertyNode objects here)
  99     char buf[256];
 100     for(int i=0; i<_airplane.numThrusters(); i++) {
 101         Thruster* t = _airplane.getThruster(i);
 102
 103         sprintf(buf, "/engines/engine[%d]/out-of-fuel", i);
 104         t->setFuelState(!fgGetBool(buf));
 105
 106         sprintf(buf, "/engines/engine[%d]/fuel-consumed-lbs", i);
 107         double consumed = fgGetDouble(buf) + dt * KG2LBS * t->getFuelFlow();
 108         fgSetDouble(buf, consumed);
 109     }
 110     for(int i=0; i<_airplane.numTanks(); i++) {
 111         sprintf(buf, "/consumables/fuel/tank[%d]/level-lbs", i);
 112         _airplane.setFuel(i, LBS2KG * fgGetFloat(buf));
 113     }
 114     _airplane.calcFuelWeights();
 115
 116     setOutputProperties(dt);
 117 }
 118
 119 Airplane* FGFDM::getAirplane()
 120 {
 121     return &_airplane;
 122 }
 123
 124 void FGFDM::init()
 125 {
 126     // Allows the user to start with something other than full fuel
 127     _airplane.setFuelFraction(fgGetFloat("/sim/fuel-fraction", 1));
 128
 129     // Read out the resulting fuel state
 130     char buf[256];
 131     for(int i=0; i<_airplane.numTanks(); i++) {
 132         sprintf(buf, "/consumables/fuel/tank[%d]/level-lbs", i);
 133         fgSetDouble(buf, _airplane.getFuel(i) * KG2LBS);
 134
 135         double density = _airplane.getFuelDensity(i);
 136         sprintf(buf, "/consumables/fuel/tank[%d]/density-ppg", i);
 137         fgSetDouble(buf, density * (KG2LBS/CM2GALS));
 138
 139 // set in TankProperties class
 140 //        sprintf(buf, "/consumables/fuel/tank[%d]/level-gal_us", i);
 141 //        fgSetDouble(buf, _airplane.getFuel(i) * CM2GALS / density);
 142
 143         sprintf(buf, "/consumables/fuel/tank[%d]/capacity-gal_us", i);
 144         fgSetDouble(buf, CM2GALS * _airplane.getTankCapacity(i)/density);
 145     }
 146
 147     // This has a nasty habit of being false at startup.  That's not
 148     // good.
 149     fgSetBool("/controls/gear/gear-down", true);
 150
 151     _airplane.getModel()->setTurbulence(_turb);
 152 }
 153
 154 // Not the worlds safest parser.  But it's short & sweet.
 155 void FGFDM::startElement(const char* name, const XMLAttributes &atts)
 156 {
 157     XMLAttributes* a = (XMLAttributes*)&atts;
 158     float v[3];
 159     char buf[64];
 160
 161     if(eq(name, "airplane")) {
 162         _airplane.setWeight(attrf(a, "mass") * LBS2KG);
 163     } else if(eq(name, "approach")) {
 164         float spd = attrf(a, "speed") * KTS2MPS;
 165         float alt = attrf(a, "alt", 0) * FT2M;
 166         float aoa = attrf(a, "aoa", 0) * DEG2RAD;
 167         float gla = attrf(a, "glide-angle", 0) * DEG2RAD;
 168         _airplane.setApproach(spd, alt, aoa, attrf(a, "fuel", 0.2),gla);
 169         _cruiseCurr = false;
 170     } else if(eq(name, "cruise")) {
 171         float spd = attrf(a, "speed") * KTS2MPS;
 172         float alt = attrf(a, "alt") * FT2M;
 173         float gla = attrf(a, "glide-angle", 0) * DEG2RAD;
 174         _airplane.setCruise(spd, alt, attrf(a, "fuel", 0.5),gla);
 175         _cruiseCurr = true;
 176     } else if(eq(name, "solve-weight")) {
 177         int idx = attri(a, "idx");
 178         float wgt = attrf(a, "weight") * LBS2KG;
 179         _airplane.addSolutionWeight(!_cruiseCurr, idx, wgt);
 180     } else if(eq(name, "cockpit")) {
 181         v[0] = attrf(a, "x");
 182         v[1] = attrf(a, "y");
 183         v[2] = attrf(a, "z");
 184         _airplane.setPilotPos(v);
 185     } else if(eq(name, "rotor")) {
 186         _airplane.getModel()->getRotorgear()->addRotor(parseRotor(a, name));
 187     } else if(eq(name, "rotorgear")) {
 188         Rotorgear* r = _airplane.getModel()->getRotorgear();
 189         _currObj = r;
 190         #define p(x) if (a->hasAttribute(#x)) r->setParameter((char *)#x,attrf(a,#x) );
 191         #define p2(x,y) if (a->hasAttribute(y)) r->setParameter((char *)#x,attrf(a,y) );
 192         p2(max_power_engine,"max-power-engine")
 193         p2(engine_prop_factor,"engine-prop-factor")
 194         p(yasimdragfactor)
 195         p(yasimliftfactor)
 196         p2(max_power_rotor_brake,"max-power-rotor-brake")
 197         p2(rotorgear_friction,"rotorgear-friction")
 198         p2(engine_accel_limit,"engine-accel-limit")
 199         #undef p
 200         #undef p2
 201         r->setInUse();
 202     } else if(eq(name, "wing")) {
 203         _airplane.setWing(parseWing(a, name));
 204     } else if(eq(name, "hstab")) {
 205         _airplane.setTail(parseWing(a, name));
 206     } else if(eq(name, "vstab") || eq(name, "mstab")) {
 207         _airplane.addVStab(parseWing(a, name));
 208     } else if(eq(name, "piston-engine")) {
 209         parsePistonEngine(a);
 210     } else if(eq(name, "turbine-engine")) {
 211         parseTurbineEngine(a);
 212     } else if(eq(name, "propeller")) {
 213         parsePropeller(a);
 214     } else if(eq(name, "thruster")) {
 215         SimpleJet* j = new SimpleJet();
 216         _currObj = j;
 217         v[0] = attrf(a, "x"); v[1] = attrf(a, "y"); v[2] = attrf(a, "z");
 218         j->setPosition(v);
 219         _airplane.addThruster(j, 0, v);
 220         v[0] = attrf(a, "vx"); v[1] = attrf(a, "vy"); v[2] = attrf(a, "vz");
 221         j->setDirection(v);
 222         j->setThrust(attrf(a, "thrust") * LBS2N);
 223     } else if(eq(name, "jet")) {
 224         Jet* j = new Jet();
 225         _currObj = j;
 226         v[0] = attrf(a, "x");
 227         v[1] = attrf(a, "y");
 228         v[2] = attrf(a, "z");
 229         float mass = attrf(a, "mass") * LBS2KG;
 230         j->setMaxThrust(attrf(a, "thrust") * LBS2N,
 231                         attrf(a, "afterburner", 0) * LBS2N);
 232         j->setVectorAngle(attrf(a, "rotate", 0) * DEG2RAD);
 233         j->setReverseThrust(attrf(a, "reverse", 0.2));
 234
 235         float n1min = attrf(a, "n1-idle", 55);
 236         float n1max = attrf(a, "n1-max", 102);
 237         float n2min = attrf(a, "n2-idle", 73);
 238         float n2max = attrf(a, "n2-max", 103);
 239         j->setRPMs(n1min, n1max, n2min, n2max);
 240
 241         j->setTSFC(attrf(a, "tsfc", 0.8));
 242         if(a->hasAttribute("egt"))  j->setEGT(attrf(a, "egt"));
 243         if(a->hasAttribute("epr"))  j->setEPR(attrf(a, "epr"));
 244         if(a->hasAttribute("exhaust-speed"))
 245             j->setVMax(attrf(a, "exhaust-speed") * KTS2MPS);
 246         if(a->hasAttribute("spool-time"))
 247             j->setSpooling(attrf(a, "spool-time"));
 248
 249         j->setPosition(v);
 250         _airplane.addThruster(j, mass, v);
 251         sprintf(buf, "/engines/engine[%d]", _nextEngine++);
 252         EngRec* er = new EngRec();
 253         er->eng = j;
 254         er->prefix = dup(buf);
 255         _thrusters.add(er);
 256     } else if(eq(name, "hitch")) {
 257         Hitch* h = new Hitch(a->getValue("name"));
 258         _currObj = h;
 259         v[0] = attrf(a, "x");
 260         v[1] = attrf(a, "y");
 261         v[2] = attrf(a, "z");
 262         h->setPosition(v);
 263         if(a->hasAttribute("force-is-calculated-by-other")) h->setForceIsCalculatedByOther(attrb(a,"force-is-calculated-by-other"));
 264         _airplane.addHitch(h);
 265     } else if(eq(name, "tow")) {
 266         Hitch* h = (Hitch*)_currObj;
 267         if(a->hasAttribute("length"))
 268             h->setTowLength(attrf(a, "length"));
 269         if(a->hasAttribute("elastic-constant"))
 270             h->setTowElasticConstant(attrf(a, "elastic-constant"));
 271         if(a->hasAttribute("break-force"))
 272             h->setTowBreakForce(attrf(a, "break-force"));
 273         if(a->hasAttribute("weight-per-meter"))
 274             h->setTowWeightPerM(attrf(a, "weight-per-meter"));
 275         if(a->hasAttribute("mp-auto-connect-period"))
 276             h->setMpAutoConnectPeriod(attrf(a, "mp-auto-connect-period"));
 277     } else if(eq(name, "winch")) {
 278         Hitch* h = (Hitch*)_currObj;
 279         double pos[3];
 280         pos[0] = attrd(a, "x",0);
 281         pos[1] = attrd(a, "y",0);
 282         pos[2] = attrd(a, "z",0);
 283         h->setWinchPosition(pos);
 284         if(a->hasAttribute("max-speed"))
 285             h->setWinchMaxSpeed(attrf(a, "max-speed"));
 286         if(a->hasAttribute("power"))
 287             h->setWinchPower(attrf(a, "power") * 1000);
 288         if(a->hasAttribute("max-force"))
 289             h->setWinchMaxForce(attrf(a, "max-force"));
 290         if(a->hasAttribute("initial-tow-length"))
 291             h->setWinchInitialTowLength(attrf(a, "initial-tow-length"));
 292         if(a->hasAttribute("max-tow-length"))
 293             h->setWinchMaxTowLength(attrf(a, "max-tow-length"));
 294         if(a->hasAttribute("min-tow-length"))
 295             h->setWinchMinTowLength(attrf(a, "min-tow-length"));
 296     } else if(eq(name, "gear")) {
 297         Gear* g = new Gear();
 298         _currObj = g;
 299         v[0] = attrf(a, "x");
 300         v[1] = attrf(a, "y");
 301         v[2] = attrf(a, "z");
 302         g->setPosition(v);
 303         float nrm = Math::mag3(v);
 304         if (_vehicle_radius < nrm)
 305             _vehicle_radius = nrm;
 306         if(a->hasAttribute("upx")) {
 307             v[0] = attrf(a, "upx");
 308             v[1] = attrf(a, "upy");
 309             v[2] = attrf(a, "upz");
 310             Math::unit3(v, v);
 311         } else {
 312             v[0] = 0;
 313             v[1] = 0;
 314             v[2] = 1;
 315         }
 316         for(int i=0; i<3; i++)
 317             v[i] *= attrf(a, "compression", 1);
 318         g->setCompression(v);
 319         g->setBrake(attrf(a, "skid", 0));
 320         g->setInitialLoad(attrf(a, "initial-load", 0));
 321         g->setStaticFriction(attrf(a, "sfric", 0.8));
 322         g->setDynamicFriction(attrf(a, "dfric", 0.7));
 323         g->setSpring(attrf(a, "spring", 1));
 324         g->setDamping(attrf(a, "damp", 1));
 325         if(a->hasAttribute("on-water")) g->setOnWater(attrb(a,"on-water"));
 326         if(a->hasAttribute("on-solid")) g->setOnSolid(attrb(a,"on-solid"));
 327         if(a->hasAttribute("ignored-by-solver")) g->setIgnoreWhileSolving(attrb(a,"ignored-by-solver"));
 328         g->setSpringFactorNotPlaning(attrf(a, "spring-factor-not-planing", 1));
 329         g->setSpeedPlaning(attrf(a, "speed-planing", 0) * KTS2MPS);
 330         g->setReduceFrictionByExtension(attrf(a, "reduce-friction-by-extension", 0));
 331         _airplane.addGear(g);
 332     } else if(eq(name, "hook")) {
 333         Hook* h = new Hook();
 334         _currObj = h;
 335         v[0] = attrf(a, "x");
 336         v[1] = attrf(a, "y");
 337         v[2] = attrf(a, "z");
 338         h->setPosition(v);
 339         float length = attrf(a, "length", 1.0);
 340         h->setLength(length);
 341         float nrm = length+Math::mag3(v);
 342         if (_vehicle_radius < nrm)
 343             _vehicle_radius = nrm;
 344         h->setDownAngle(attrf(a, "down-angle", 70) * DEG2RAD);
 345         h->setUpAngle(attrf(a, "up-angle", 0) * DEG2RAD);
 346         _airplane.addHook(h);
 347     } else if(eq(name, "launchbar")) {
 348         Launchbar* l = new Launchbar();
 349         _currObj = l;
 350         v[0] = attrf(a, "x");
 351         v[1] = attrf(a, "y");
 352         v[2] = attrf(a, "z");
 353         l->setLaunchbarMount(v);
 354         v[0] = attrf(a, "holdback-x", v[0]);
 355         v[1] = attrf(a, "holdback-y", v[1]);
 356         v[2] = attrf(a, "holdback-z", v[2]);
 357         l->setHoldbackMount(v);
 358         float length = attrf(a, "length", 1.0);
 359         l->setLength(length);
 360         l->setDownAngle(attrf(a, "down-angle", 45) * DEG2RAD);
 361         l->setUpAngle(attrf(a, "up-angle", -45) * DEG2RAD);
 362         l->setHoldbackLength(attrf(a, "holdback-length", 2.0));
 363         _airplane.addLaunchbar(l);
 364     } else if(eq(name, "fuselage")) {
 365         float b[3];
 366         v[0] = attrf(a, "ax");
 367         v[1] = attrf(a, "ay");
 368         v[2] = attrf(a, "az");
 369         b[0] = attrf(a, "bx");
 370         b[1] = attrf(a, "by");
 371         b[2] = attrf(a, "bz");
 372         float taper = attrf(a, "taper", 1);
 373         float mid = attrf(a, "midpoint", 0.5);
 374         float cx = attrf(a, "cx", 1);
 375         float cy = attrf(a, "cy", 1);
 376         float cz = attrf(a, "cz", 1);
 377         float idrag = attrf(a, "idrag", 1);
 378         _airplane.addFuselage(v, b, attrf(a, "width"), taper, mid,
 379             cx, cy, cz, idrag);
 380     } else if(eq(name, "tank")) {
 381         v[0] = attrf(a, "x");
 382         v[1] = attrf(a, "y");
 383         v[2] = attrf(a, "z");
 384         float density = 6.0; // gasoline, in lbs/gal
 385         if(a->hasAttribute("jet")) density = 6.72;
 386         density *= LBS2KG*CM2GALS;
 387         _airplane.addTank(v, attrf(a, "capacity") * LBS2KG, density);
 388     } else if(eq(name, "ballast")) {
 389         v[0] = attrf(a, "x");
 390         v[1] = attrf(a, "y");
 391         v[2] = attrf(a, "z");
 392         _airplane.addBallast(v, attrf(a, "mass") * LBS2KG);
 393     } else if(eq(name, "weight")) {
 394         parseWeight(a);
 395     } else if(eq(name, "stall")) {
 396         Wing* w = (Wing*)_currObj;
 397         w->setStall(attrf(a, "aoa") * DEG2RAD);
 398         w->setStallWidth(attrf(a, "width", 2) * DEG2RAD);
 399         w->setStallPeak(attrf(a, "peak", 1.5));
 400     } else if(eq(name, "flap0")) {
 401         ((Wing*)_currObj)->setFlap0(attrf(a, "start"), attrf(a, "end"),
 402                                     attrf(a, "lift"), attrf(a, "drag"));
 403     } else if(eq(name, "flap1")) {
 404         ((Wing*)_currObj)->setFlap1(attrf(a, "start"), attrf(a, "end"),
 405                                     attrf(a, "lift"), attrf(a, "drag"));
 406     } else if(eq(name, "slat")) {
 407         ((Wing*)_currObj)->setSlat(attrf(a, "start"), attrf(a, "end"),
 408                                    attrf(a, "aoa"), attrf(a, "drag"));
 409     } else if(eq(name, "spoiler")) {
 410         ((Wing*)_currObj)->setSpoiler(attrf(a, "start"), attrf(a, "end"),
 411                                       attrf(a, "lift"), attrf(a, "drag"));
 412     /* } else if(eq(name, "collective")) {
 413         ((Rotor*)_currObj)->setcollective(attrf(a, "min"), attrf(a, "max"));
 414     } else if(eq(name, "cyclic")) {
 415         ((Rotor*)_currObj)->setcyclic(attrf(a, "ail"), attrf(a, "ele"));
 416     */
 417     } else if(eq(name, "actionpt")) {
 418         v[0] = attrf(a, "x");
 419         v[1] = attrf(a, "y");
 420         v[2] = attrf(a, "z");
 421         ((Thruster*)_currObj)->setPosition(v);
 422     } else if(eq(name, "dir")) {
 423         v[0] = attrf(a, "x");
 424         v[1] = attrf(a, "y");
 425         v[2] = attrf(a, "z");
 426         ((Thruster*)_currObj)->setDirection(v);
 427     } else if(eq(name, "control-setting")) {
 428         // A cruise or approach control setting
 429         const char* axis = a->getValue("axis");
 430         float value = attrf(a, "value", 0);
 431         if(_cruiseCurr)
 432             _airplane.addCruiseControl(parseAxis(axis), value);
 433         else
 434             _airplane.addApproachControl(parseAxis(axis), value);
 435     } else if(eq(name, "control-input")) {
 436
 437         // A mapping of input property to a control
 438         int axis = parseAxis(a->getValue("axis"));
 439         int control = parseOutput(a->getValue("control"));
 440         int opt = 0;
 441         opt |= a->hasAttribute("split") ? ControlMap::OPT_SPLIT : 0;
 442         opt |= a->hasAttribute("invert") ? ControlMap::OPT_INVERT : 0;
 443         opt |= a->hasAttribute("square") ? ControlMap::OPT_SQUARE : 0;
 444
 445         ControlMap* cm = _airplane.getControlMap();
 446         if(a->hasAttribute("src0")) {
 447                            cm->addMapping(axis, control, _currObj, opt,
 448                            attrf(a, "src0"), attrf(a, "src1"),
 449                            attrf(a, "dst0"), attrf(a, "dst1"));
 450         } else {
 451             cm->addMapping(axis, control, _currObj, opt);
 452         }
 453     } else if(eq(name, "control-output")) {
 454         // A property output for a control on the current object
 455         ControlMap* cm = _airplane.getControlMap();
 456         int type = parseOutput(a->getValue("control"));
 457         int handle = cm->getOutputHandle(_currObj, type);
 458
 459         PropOut* p = new PropOut();
 460         p->prop = fgGetNode(a->getValue("prop"), true);
 461         p->handle = handle;
 462         p->type = type;
 463         p->left = !(a->hasAttribute("side") &&
 464                         eq("right", a->getValue("side")));
 465         p->min = attrf(a, "min", cm->rangeMin(type));
 466         p->max = attrf(a, "max", cm->rangeMax(type));
 467         _controlProps.add(p);
 468
 469     } else if(eq(name, "control-speed")) {
 470         ControlMap* cm = _airplane.getControlMap();
 471         int type = parseOutput(a->getValue("control"));
 472         int handle = cm->getOutputHandle(_currObj, type);
 473         float time = attrf(a, "transition-time", 0);
 474
 475         cm->setTransitionTime(handle, time);
 476     } else {
 477         SG_LOG(SG_FLIGHT,SG_ALERT,"Unexpected tag '"
 478                << name << "' found in YASim aircraft description");
 479         exit(1);
 480     }
 481 }
 482
 483 void FGFDM::getExternalInput(float dt)
 484 {
 485     char buf[256];
 486
 487     _turb->setMagnitude(fgGetFloat("/environment/turbulence/magnitude-norm"));
 488     _turb->update(dt, fgGetFloat("/environment/turbulence/rate-hz"));
 489
 490     // The control axes
 491     ControlMap* cm = _airplane.getControlMap();
 492     cm->reset();
 493     int i;
 494     for(i=0; i<_axes.size(); i++) {
 495         AxisRec* a = (AxisRec*)_axes.get(i);
 496         float val = fgGetFloat(a->name, 0);
 497         cm->setInput(a->handle, val);
 498     }
 499     cm->applyControls(dt);
 500
 501     // Weights
 502     for(i=0; i<_weights.size(); i++) {
 503         WeightRec* wr = (WeightRec*)_weights.get(i);
 504         _airplane.setWeight(wr->handle, LBS2KG * fgGetFloat(wr->prop));
 505     }
 506
 507     for(i=0; i<_thrusters.size(); i++) {
 508         EngRec* er = (EngRec*)_thrusters.get(i);
 509         Thruster* t = er->eng;
 510
 511         if(t->getPropEngine()) {
 512             PropEngine* p = t->getPropEngine();
 513             sprintf(buf, "%s/rpm", er->prefix);
 514             p->setOmega(fgGetFloat(buf, 500) * RPM2RAD);
 515         }
 516     }
 517 }
 518
 519 // Linearly "seeks" a property by the specified fraction of the way to
 520 // the target value.  Used to emulate "slowly changing" output values.
 521 static void moveprop(SGPropertyNode* node, const char* prop,
 522                     float target, float frac)
 523 {
 524     float val = node->getFloatValue(prop);
 525     if(frac > 1) frac = 1;
 526     if(frac < 0) frac = 0;
 527     val += (target - val) * frac;
 528     node->setFloatValue(prop, val);
 529 }
 530
 531 void FGFDM::setOutputProperties(float dt)
 532 {
 533     // char buf[256];
 534     int i;
 535
 536     float grossWgt = _airplane.getModel()->getBody()->getTotalMass() * KG2LBS;
 537     fgSetFloat("/yasim/gross-weight-lbs", grossWgt);
 538
 539     ControlMap* cm = _airplane.getControlMap();
 540     for(i=0; i<_controlProps.size(); i++) {
 541         PropOut* p = (PropOut*)_controlProps.get(i);
 542         float val = (p->left
 543                      ? cm->getOutput(p->handle)
 544                      : cm->getOutputR(p->handle));
 545         float rmin = cm->rangeMin(p->type);
 546         float rmax = cm->rangeMax(p->type);
 547         float frac = (val - rmin) / (rmax - rmin);
 548         val = frac*(p->max - p->min) + p->min;
 549         p->prop->setFloatValue(val);
 550     }
 551
 552     for(i=0; i<_airplane.getRotorgear()->getNumRotors(); i++) {
 553         Rotor*r=(Rotor*)_airplane.getRotorgear()->getRotor(i);
 554         int j = 0;
 555         float f;
 556         char b[256];
 557         while((j = r->getValueforFGSet(j, b, &f)))
 558             if(b[0]) fgSetFloat(b,f);
 559         j=0;
 560         while((j = _airplane.getRotorgear()->getValueforFGSet(j, b, &f)))
 561             if(b[0]) fgSetFloat(b,f);
 562         for(j=0; j < r->numRotorparts(); j+=r->numRotorparts()>>2) {
 563             Rotorpart* s = (Rotorpart*)r->getRotorpart(j);
 564             char *b;
 565             int k;
 566             for(k=0; k<2; k++) {
 567                 b=s->getAlphaoutput(k);
 568                 if(b[0]) fgSetFloat(b, s->getAlpha(k));
 569             }
 570         }
 571     }
 572
 573     // Use the density of the first tank, or a dummy value if no tanks
 574     float fuelDensity = 1.0;
 575     if(_airplane.numTanks())
 576         fuelDensity = _airplane.getFuelDensity(0);
 577     for(i=0; i<_thrusters.size(); i++) {
 578         EngRec* er = (EngRec*)_thrusters.get(i);
 579         Thruster* t = er->eng;
 580         SGPropertyNode * node = fgGetNode("engines/engine", i, true);
 581
 582         // Set: running, cranking, prop-thrust, max-hp, power-pct
 583         node->setBoolValue("running", t->isRunning());
 584         node->setBoolValue("cranking", t->isCranking());
 585
 586         float tmp[3];
 587         t->getThrust(tmp);
 588         float lbs = Math::mag3(tmp) * (KG2LBS/9.8);
 589         node->setFloatValue("prop-thrust", lbs); // Deprecated name
 590         node->setFloatValue("thrust-lbs", lbs);
 591         node->setFloatValue("fuel-flow-gph",
 592                             (t->getFuelFlow()/fuelDensity) * 3600 * CM2GALS);
 593
 594         if(t->getPropEngine()) {
 595             PropEngine* p = t->getPropEngine();
 596             node->setFloatValue("rpm", p->getOmega() * (1/RPM2RAD));
 597             node->setFloatValue("torque-ftlb",
 598                                 p->getEngine()->getTorque() * NM2FTLB);
 599
 600             if(p->getEngine()->isPistonEngine()) {
 601                 PistonEngine* pe = p->getEngine()->isPistonEngine();
 602                 node->setFloatValue("mp-osi", pe->getMP() * (1/INHG2PA));
 603                 node->setFloatValue("mp-inhg", pe->getMP() * (1/INHG2PA));
 604                 node->setFloatValue("egt-degf",
 605                                     pe->getEGT() * K2DEGF + K2DEGFOFFSET);
 606                 node->setFloatValue("oil-temperature-degf",
 607                                     pe->getOilTemp() * K2DEGF + K2DEGFOFFSET);
 608                 node->setFloatValue("boost-gauge-inhg",
 609                                     pe->getBoost() * (1/INHG2PA));
 610             } else if(p->getEngine()->isTurbineEngine()) {
 611                 TurbineEngine* te = p->getEngine()->isTurbineEngine();
 612                 node->setFloatValue("n2", te->getN2());
 613             }
 614         }
 615
 616         if(t->getJet()) {
 617             Jet* j = t->getJet();
 618             node->setFloatValue("n1", j->getN1());
 619             node->setFloatValue("n2", j->getN2());
 620             node->setFloatValue("epr", j->getEPR());
 621             node->setFloatValue("egt-degf",
 622                                 j->getEGT() * K2DEGF + K2DEGFOFFSET);
 623
 624             // These are "unmodeled" values that are still needed for
 625             // many cockpits.  Tie them all to the N1 speed, but
 626             // normalize the numbers to the range [0:1] so the
 627             // cockpit code can scale them to the right values.
 628             float pnorm = j->getPerfNorm();
 629             moveprop(node, "oilp-norm", pnorm, dt/3); // 3s seek time
 630             moveprop(node, "oilt-norm", pnorm, dt/30); // 30s
 631             moveprop(node, "itt-norm", pnorm, dt/1); // 1s
 632         }
 633     }
 634 }
 635
 636 Wing* FGFDM::parseWing(XMLAttributes* a, const char* type)
 637 {
 638     Wing* w = new Wing();
 639
 640     float defDihed = 0;
 641     if(eq(type, "vstab"))
 642         defDihed = 90;
 643     else
 644         w->setMirror(true);
 645
 646     float pos[3];
 647     pos[0] = attrf(a, "x");
 648     pos[1] = attrf(a, "y");
 649     pos[2] = attrf(a, "z");
 650     w->setBase(pos);
 651
 652     w->setLength(attrf(a, "length"));
 653     w->setChord(attrf(a, "chord"));
 654     w->setSweep(attrf(a, "sweep", 0) * DEG2RAD);
 655     w->setTaper(attrf(a, "taper", 1));
 656     w->setDihedral(attrf(a, "dihedral", defDihed) * DEG2RAD);
 657     w->setCamber(attrf(a, "camber", 0));
 658
 659     // These come in with positive indicating positive AoA, but the
 660     // internals expect a rotation about the left-pointing Y axis, so
 661     // invert the sign.
 662     w->setIncidence(attrf(a, "incidence", 0) * DEG2RAD * -1);
 663     w->setTwist(attrf(a, "twist", 0) * DEG2RAD * -1);
 664
 665     // The 70% is a magic number that sorta kinda seems to match known
 666     // throttle settings to approach speed.
 667     w->setInducedDrag(0.7*attrf(a, "idrag", 1));
 668
 669     float effect = attrf(a, "effectiveness", 1);
 670     w->setDragScale(w->getDragScale()*effect);
 671
 672     _currObj = w;
 673     return w;
 674 }
 675
 676 Rotor* FGFDM::parseRotor(XMLAttributes* a, const char* type)
 677 {
 678     Rotor* w = new Rotor();
 679
 680     // float defDihed = 0;
 681
 682     float pos[3];
 683     pos[0] = attrf(a, "x");
 684     pos[1] = attrf(a, "y");
 685     pos[2] = attrf(a, "z");
 686     w->setBase(pos);
 687
 688     float normal[3];
 689     normal[0] = attrf(a, "nx");
 690     normal[1] = attrf(a, "ny");
 691     normal[2] = attrf(a, "nz");
 692     w->setNormal(normal);
 693
 694     float forward[3];
 695     forward[0] = attrf(a, "fx");
 696     forward[1] = attrf(a, "fy");
 697     forward[2] = attrf(a, "fz");
 698     w->setForward(forward);
 699
 700     w->setMaxCyclicail(attrf(a, "maxcyclicail", 7.6));
 701     w->setMaxCyclicele(attrf(a, "maxcyclicele", 4.94));
 702     w->setMinCyclicail(attrf(a, "mincyclicail", -7.6));
 703     w->setMinCyclicele(attrf(a, "mincyclicele", -4.94));
 704     w->setMaxCollective(attrf(a, "maxcollective", 15.8));
 705     w->setMinCollective(attrf(a, "mincollective", -0.2));
 706     w->setDiameter(attrf(a, "diameter", 10.2));
 707     w->setWeightPerBlade(attrf(a, "weightperblade", 44));
 708     w->setNumberOfBlades(attrf(a, "numblades", 4));
 709     w->setRelBladeCenter(attrf(a, "relbladecenter", 0.7));
 710     w->setDynamic(attrf(a, "dynamic", 0.7));
 711     w->setDelta3(attrf(a, "delta3", 0));
 712     w->setDelta(attrf(a, "delta", 0));
 713     w->setTranslift(attrf(a, "translift", 0.05));
 714     w->setC2(attrf(a, "dragfactor", 1));
 715     w->setStepspersecond(attrf(a, "stepspersecond", 120));
 716     w->setPhiNull((attrf(a, "phi0", 0))*YASIM_PI/180);
 717     w->setRPM(attrf(a, "rpm", 424));
 718     w->setRelLenHinge(attrf(a, "rellenflaphinge", 0.07));
 719     w->setAlpha0((attrf(a, "flap0", -5))*YASIM_PI/180);
 720     w->setAlphamin((attrf(a, "flapmin", -15))/180*YASIM_PI);
 721     w->setAlphamax((attrf(a, "flapmax",  15))*YASIM_PI/180);
 722     w->setAlpha0factor(attrf(a, "flap0factor", 1));
 723     w->setTeeterdamp(attrf(a,"teeterdamp",.0001));
 724     w->setMaxteeterdamp(attrf(a,"maxteeterdamp",1000));
 725     w->setRelLenTeeterHinge(attrf(a,"rellenteeterhinge",0.01));
 726     w->setBalance(attrf(a,"balance",1.0));
 727     w->setMinTiltYaw(attrf(a,"mintiltyaw",0.0));
 728     w->setMinTiltPitch(attrf(a,"mintiltpitch",0.0));
 729     w->setMinTiltRoll(attrf(a,"mintiltroll",0.0));
 730     w->setMaxTiltYaw(attrf(a,"maxtiltyaw",0.0));
 731     w->setMaxTiltPitch(attrf(a,"maxtiltpitch",0.0));
 732     w->setMaxTiltRoll(attrf(a,"maxtiltroll",0.0));
 733     w->setTiltCenterX(attrf(a,"tiltcenterx",0.0));
 734     w->setTiltCenterY(attrf(a,"tiltcentery",0.0));
 735     w->setTiltCenterZ(attrf(a,"tiltcenterz",0.0));
 736     w->setDownwashFactor(attrf(a, "downwashfactor", 1));
 737     if(attrb(a,"ccw"))
 738        w->setCcw(1);
 739     if(attrb(a,"sharedflaphinge"))
 740        w->setSharedFlapHinge(true);
 741
 742     if(a->hasAttribute("name"))
 743        w->setName(a->getValue("name") );
 744     if(a->hasAttribute("alphaout0"))
 745        w->setAlphaoutput(0,a->getValue("alphaout0") );
 746     if(a->hasAttribute("alphaout1"))  w->setAlphaoutput(1,a->getValue("alphaout1") );
 747     if(a->hasAttribute("alphaout2"))  w->setAlphaoutput(2,a->getValue("alphaout2") );
 748     if(a->hasAttribute("alphaout3"))  w->setAlphaoutput(3,a->getValue("alphaout3") );
 749     if(a->hasAttribute("coneout"))  w->setAlphaoutput(4,a->getValue("coneout") );
 750     if(a->hasAttribute("yawout"))   w->setAlphaoutput(5,a->getValue("yawout") );
 751     if(a->hasAttribute("rollout"))  w->setAlphaoutput(6,a->getValue("rollout") );
 752
 753     w->setPitchA(attrf(a, "pitch-a", 10));
 754     w->setPitchB(attrf(a, "pitch-b", 10));
 755     w->setForceAtPitchA(attrf(a, "forceatpitch-a", 3000));
 756     w->setPowerAtPitch0(attrf(a, "poweratpitch-0", 300));
 757     w->setPowerAtPitchB(attrf(a, "poweratpitch-b", 3000));
 758     if(attrb(a,"notorque"))
 759        w->setNotorque(1);
 760
 761 #define p(x) if (a->hasAttribute(#x)) w->setParameter((char *)#x,attrf(a,#x) );
 762 #define p2(x,y) if (a->hasAttribute(y)) w->setParameter((char *)#x,attrf(a,y) );
 763     p2(translift_ve,"translift-ve")
 764     p2(translift_maxfactor,"translift-maxfactor")
 765     p2(ground_effect_constant,"ground-effect-constant")
 766     p2(vortex_state_lift_factor,"vortex-state-lift-factor")
 767     p2(vortex_state_c1,"vortex-state-c1")
 768     p2(vortex_state_c2,"vortex-state-c2")
 769     p2(vortex_state_c3,"vortex-state_c3")
 770     p2(vortex_state_e1,"vortex-state-e1")
 771     p2(vortex_state_e2,"vortex-state-e2")
 772     p(twist)
 773     p2(number_of_segments,"number-of-segments")
 774     p2(number_of_parts,"number-of-parts")
 775     p2(rel_len_where_incidence_is_measured,"rel-len-where-incidence-is-measured")
 776     p(chord)
 777     p(taper)
 778     p2(airfoil_incidence_no_lift,"airfoil-incidence-no-lift")
 779     p2(rel_len_blade_start,"rel-len-blade-start")
 780     p2(incidence_stall_zero_speed,"incidence-stall-zero-speed")
 781     p2(incidence_stall_half_sonic_speed,"incidence-stall-half-sonic-speed")
 782     p2(lift_factor_stall,"lift-factor-stall")
 783     p2(stall_change_over,"stall-change-over")
 784     p2(drag_factor_stall,"drag-factor-stall")
 785     p2(airfoil_lift_coefficient,"airfoil-lift-coefficient")
 786     p2(airfoil_drag_coefficient0,"airfoil-drag-coefficient0")
 787     p2(airfoil_drag_coefficient1,"airfoil-drag-coefficient1")
 788     p2(cyclic_factor,"cyclic-factor")
 789     p2(rotor_correction_factor,"rotor-correction-factor")
 790 #undef p
 791 #undef p2
 792     _currObj = w;
 793     return w;
 794 }
 795
 796 void FGFDM::parsePistonEngine(XMLAttributes* a)
 797 {
 798     float engP = attrf(a, "eng-power") * HP2W;
 799     float engS = attrf(a, "eng-rpm") * RPM2RAD;
 800
 801     PistonEngine* eng = new PistonEngine(engP, engS);
 802
 803     if(a->hasAttribute("displacement"))
 804         eng->setDisplacement(attrf(a, "displacement") * CIN2CM);
 805
 806     if(a->hasAttribute("compression"))
 807         eng->setCompression(attrf(a, "compression"));
 808
 809     if(a->hasAttribute("min-throttle"))
 810         eng->setMinThrottle(attrf(a, "min-throttle"));
 811
 812     if(a->hasAttribute("turbo-mul")) {
 813         float mul = attrf(a, "turbo-mul");
 814         float mp = attrf(a, "wastegate-mp", 1e6) * INHG2PA;
 815         eng->setTurboParams(mul, mp);
 816         eng->setTurboLag(attrf(a, "turbo-lag", 2));
 817     }
 818
 819     if(a->hasAttribute("supercharger"))
 820         eng->setSupercharger(attrb(a, "supercharger"));
 821
 822     ((PropEngine*)_currObj)->setEngine(eng);
 823 }
 824
 825 void FGFDM::parseTurbineEngine(XMLAttributes* a)
 826 {
 827     float power = attrf(a, "eng-power") * HP2W;
 828     float omega = attrf(a, "eng-rpm") * RPM2RAD;
 829     float alt = attrf(a, "alt") * FT2M;
 830     float flatRating = attrf(a, "flat-rating") * HP2W;
 831     TurbineEngine* eng = new TurbineEngine(power, omega, alt, flatRating);
 832
 833     if(a->hasAttribute("n2-low-idle"))
 834         eng->setN2Range(attrf(a, "n2-low-idle"), attrf(a, "n2-high-idle"),
 835                         attrf(a, "n2-max"));
 836
 837     // Nasty units conversion: lbs/hr per hp -> kg/s per watt
 838     if(a->hasAttribute("bsfc"))
 839         eng->setFuelConsumption(attrf(a, "bsfc") * (LBS2KG/(3600*HP2W)));
 840
 841     ((PropEngine*)_currObj)->setEngine(eng);
 842 }
 843
 844 void FGFDM::parsePropeller(XMLAttributes* a)
 845 {
 846     // Legacy Handling for the old engines syntax:
 847     PistonEngine* eng = 0;
 848     if(a->hasAttribute("eng-power")) {
 849         SG_LOG(SG_FLIGHT,SG_ALERT, "WARNING: "
 850                << "Legacy engine definition in YASim configuration file.  "
 851                << "Please fix.");
 852         float engP = attrf(a, "eng-power") * HP2W;
 853         float engS = attrf(a, "eng-rpm") * RPM2RAD;
 854         eng = new PistonEngine(engP, engS);
 855         if(a->hasAttribute("displacement"))
 856             eng->setDisplacement(attrf(a, "displacement") * CIN2CM);
 857         if(a->hasAttribute("compression"))
 858             eng->setCompression(attrf(a, "compression"));
 859         if(a->hasAttribute("turbo-mul")) {
 860             float mul = attrf(a, "turbo-mul");
 861             float mp = attrf(a, "wastegate-mp", 1e6) * INHG2PA;
 862             eng->setTurboParams(mul, mp);
 863         }
 864     }
 865
 866     // Now parse the actual propeller definition:
 867     float cg[3];
 868     cg[0] = attrf(a, "x");
 869     cg[1] = attrf(a, "y");
 870     cg[2] = attrf(a, "z");
 871     float mass = attrf(a, "mass") * LBS2KG;
 872     float moment = attrf(a, "moment");
 873     float radius = attrf(a, "radius");
 874     float speed = attrf(a, "cruise-speed") * KTS2MPS;
 875     float omega = attrf(a, "cruise-rpm") * RPM2RAD;
 876     float power = attrf(a, "cruise-power") * HP2W;
 877     float rho = Atmosphere::getStdDensity(attrf(a, "cruise-alt") * FT2M);
 878
 879     Propeller* prop = new Propeller(radius, speed, omega, rho, power);
 880     PropEngine* thruster = new PropEngine(prop, eng, moment);
 881     _airplane.addThruster(thruster, mass, cg);
 882
 883     // Set the stops (fine = minimum pitch, coarse = maximum pitch)
 884     float fine_stop = attrf(a, "fine-stop", 0.25f);
 885     float coarse_stop = attrf(a, "coarse-stop", 4.0f);
 886     prop->setStops(fine_stop, coarse_stop);
 887
 888     if(a->hasAttribute("takeoff-power")) {
 889         float power0 = attrf(a, "takeoff-power") * HP2W;
 890         float omega0 = attrf(a, "takeoff-rpm") * RPM2RAD;
 891         prop->setTakeoff(omega0, power0);
 892     }
 893
 894     if(a->hasAttribute("max-rpm")) {
 895         float max = attrf(a, "max-rpm") * RPM2RAD;
 896         float min = attrf(a, "min-rpm") * RPM2RAD;
 897         thruster->setVariableProp(min, max);
 898     }
 899
 900     if(attrb(a, "contra"))
 901         thruster->setContraPair(true);
 902
 903     if(a->hasAttribute("manual-pitch")) {
 904         prop->setManualPitch();
 905     }
 906
 907     thruster->setGearRatio(attrf(a, "gear-ratio", 1));
 908
 909     char buf[64];
 910     sprintf(buf, "/engines/engine[%d]", _nextEngine++);
 911     EngRec* er = new EngRec();
 912     er->eng = thruster;
 913     er->prefix = dup(buf);
 914     _thrusters.add(er);
 915
 916     _currObj = thruster;
 917 }
 918
 919 // Turns a string axis name into an integer for use by the
 920 // ControlMap.  Creates a new axis if this one hasn't been defined
 921 // yet.
 922 int FGFDM::parseAxis(const char* name)
 923 {
 924     int i;
 925     for(i=0; i<_axes.size(); i++) {
 926         AxisRec* a = (AxisRec*)_axes.get(i);
 927         if(eq(a->name, name))
 928             return a->handle;
 929     }
 930
 931     // Not there, make a new one.
 932     AxisRec* a = new AxisRec();
 933     a->name = dup(name);
 934     fgGetNode( a->name, true ); // make sure the property name exists
 935     a->handle = _airplane.getControlMap()->newInput();
 936     _axes.add(a);
 937     return a->handle;
 938 }
 939
 940 int FGFDM::parseOutput(const char* name)
 941 {
 942     if(eq(name, "THROTTLE"))  return ControlMap::THROTTLE;
 943     if(eq(name, "MIXTURE"))   return ControlMap::MIXTURE;
 944     if(eq(name, "CONDLEVER")) return ControlMap::CONDLEVER;
 945     if(eq(name, "STARTER"))   return ControlMap::STARTER;
 946     if(eq(name, "MAGNETOS"))  return ControlMap::MAGNETOS;
 947     if(eq(name, "ADVANCE"))   return ControlMap::ADVANCE;
 948     if(eq(name, "REHEAT"))    return ControlMap::REHEAT;
 949     if(eq(name, "BOOST"))     return ControlMap::BOOST;
 950     if(eq(name, "VECTOR"))    return ControlMap::VECTOR;
 951     if(eq(name, "PROP"))      return ControlMap::PROP;
 952     if(eq(name, "BRAKE"))     return ControlMap::BRAKE;
 953     if(eq(name, "STEER"))     return ControlMap::STEER;
 954     if(eq(name, "EXTEND"))    return ControlMap::EXTEND;
 955     if(eq(name, "HEXTEND"))   return ControlMap::HEXTEND;
 956     if(eq(name, "LEXTEND"))   return ControlMap::LEXTEND;
 957         if(eq(name, "LACCEL"))    return ControlMap::LACCEL;
 958     if(eq(name, "INCIDENCE")) return ControlMap::INCIDENCE;
 959     if(eq(name, "FLAP0"))     return ControlMap::FLAP0;
 960     if(eq(name, "FLAP0EFFECTIVENESS"))   return ControlMap::FLAP0EFFECTIVENESS;
 961     if(eq(name, "FLAP1"))     return ControlMap::FLAP1;
 962     if(eq(name, "FLAP1EFFECTIVENESS"))   return ControlMap::FLAP1EFFECTIVENESS;
 963     if(eq(name, "SLAT"))      return ControlMap::SLAT;
 964     if(eq(name, "SPOILER"))   return ControlMap::SPOILER;
 965     if(eq(name, "CASTERING")) return ControlMap::CASTERING;
 966     if(eq(name, "PROPPITCH")) return ControlMap::PROPPITCH;
 967     if(eq(name, "PROPFEATHER")) return ControlMap::PROPFEATHER;
 968     if(eq(name, "COLLECTIVE")) return ControlMap::COLLECTIVE;
 969     if(eq(name, "CYCLICAIL")) return ControlMap::CYCLICAIL;
 970     if(eq(name, "CYCLICELE")) return ControlMap::CYCLICELE;
 971     if(eq(name, "TILTROLL")) return ControlMap::TILTROLL;
 972     if(eq(name, "TILTPITCH")) return ControlMap::TILTPITCH;
 973     if(eq(name, "TILTYAW")) return ControlMap::TILTYAW;
 974     if(eq(name, "ROTORGEARENGINEON")) return ControlMap::ROTORENGINEON;
 975     if(eq(name, "ROTORBRAKE")) return ControlMap::ROTORBRAKE;
 976     if(eq(name, "ROTORENGINEMAXRELTORQUE"))
 977         return ControlMap::ROTORENGINEMAXRELTORQUE;
 978     if(eq(name, "ROTORRELTARGET")) return ControlMap::ROTORRELTARGET;
 979     if(eq(name, "ROTORBALANCE")) return ControlMap::ROTORBALANCE;
 980     if(eq(name, "REVERSE_THRUST")) return ControlMap::REVERSE_THRUST;
 981     if(eq(name, "WASTEGATE")) return ControlMap::WASTEGATE;
 982     if(eq(name, "WINCHRELSPEED")) return ControlMap::WINCHRELSPEED;
 983     if(eq(name, "HITCHOPEN")) return ControlMap::HITCHOPEN;
 984     if(eq(name, "PLACEWINCH")) return ControlMap::PLACEWINCH;
 985     if(eq(name, "FINDAITOW")) return ControlMap::FINDAITOW;
 986
 987     SG_LOG(SG_FLIGHT,SG_ALERT,"Unrecognized control type '"
 988            << name << "' in YASim aircraft description.");
 989     exit(1);
 990
 991 }
 992
 993 void FGFDM::parseWeight(XMLAttributes* a)
 994 {
 995     WeightRec* wr = new WeightRec();
 996
 997     float v[3];
 998     v[0] = attrf(a, "x");
 999     v[1] = attrf(a, "y");
1000     v[2] = attrf(a, "z");
1001
1002     wr->prop = dup(a->getValue("mass-prop"));
1003     wr->size = attrf(a, "size", 0);
1004     wr->handle = _airplane.addWeight(v, wr->size);
1005
1006     _weights.add(wr);
1007 }
1008
1009 bool FGFDM::eq(const char* a, const char* b)
1010 {
1011     // Figure it out for yourself. :)
1012     while(*a && *b && *a == *b) { a++; b++; }
1013     return !(*a || *b);
1014 }
1015
1016 char* FGFDM::dup(const char* s)
1017 {
1018     int len=0;
1019     while(s[len++]);
1020     char* s2 = new char[len+1];
1021     char* p = s2;
1022     while((*p++ = *s++));
1023     s2[len] = 0;
1024     return s2;
1025 }
1026
1027 int FGFDM::attri(XMLAttributes* atts, const char* attr)
1028 {
1029     if(!atts->hasAttribute(attr)) {
1030         SG_LOG(SG_FLIGHT,SG_ALERT,"Missing '" << attr <<
1031                "' in YASim aircraft description");
1032         exit(1);
1033     }
1034     return attri(atts, attr, 0);
1035 }
1036
1037 int FGFDM::attri(XMLAttributes* atts, const char* attr, int def)
1038 {
1039     const char* val = atts->getValue(attr);
1040     if(val == 0) return def;
1041     else         return atol(val);
1042 }
1043
1044 float FGFDM::attrf(XMLAttributes* atts, const char* attr)
1045 {
1046     if(!atts->hasAttribute(attr)) {
1047         SG_LOG(SG_FLIGHT,SG_ALERT,"Missing '" << attr <<
1048                "' in YASim aircraft description");
1049         exit(1);
1050     }
1051     return attrf(atts, attr, 0);
1052 }
1053
1054 float FGFDM::attrf(XMLAttributes* atts, const char* attr, float def)
1055 {
1056     const char* val = atts->getValue(attr);
1057     if(val == 0) return def;
1058     else         return (float)atof(val);
1059 }
1060
1061 double FGFDM::attrd(XMLAttributes* atts, const char* attr)
1062 {
1063     if(!atts->hasAttribute(attr)) {
1064         SG_LOG(SG_FLIGHT,SG_ALERT,"Missing '" << attr <<
1065                "' in YASim aircraft description");
1066         exit(1);
1067     }
1068     return attrd(atts, attr, 0);
1069 }
1070
1071 double FGFDM::attrd(XMLAttributes* atts, const char* attr, double def)
1072 {
1073     const char* val = atts->getValue(attr);
1074     if(val == 0) return def;
1075     else         return atof(val);
1076 }
1077
1078 // ACK: the dreaded ambiguous string boolean.  Remind me to shoot Maik
1079 // when I have a chance. :).  Unless you have a parser that can check
1080 // symbol constants (we don't), this kind of coding is just a Bad
1081 // Idea.  This implementation, for example, silently returns a boolean
1082 // falsehood for values of "1", "yes", "True", and "TRUE".  Which is
1083 // especially annoying preexisting boolean attributes in the same
1084 // parser want to see "1" and will choke on a "true"...
1085 //
1086 // Unfortunately, this usage creeped into existing configuration files
1087 // while I wasn't active, and it's going to be hard to remove.  Issue
1088 // a warning to nag people into changing their ways for now...
1089 bool FGFDM::attrb(XMLAttributes* atts, const char* attr)
1090 {
1091     const char* val = atts->getValue(attr);
1092     if(val == 0) return false;
1093
1094     if(eq(val,"true")) {
1095         SG_LOG(SG_FLIGHT, SG_ALERT, "Warning: " <<
1096                "deprecated 'true' boolean in YASim configuration file.  " <<
1097                "Use numeric booleans (attribute=\"1\") instead");
1098         return true;
1099     }
1100     return attri(atts, attr, 0) ? true : false;
1101 }
1102
1103 }; // namespace yasim