]> git.mxchange.org Git - flightgear.git/blobdiff - src/FDM/JSBSim/FGLGear.cpp
Make yasim accept the launchbar and hook properties. They are not tied to anything...
[flightgear.git] / src / FDM / JSBSim / FGLGear.cpp
index 0f36ade4fd7de40cd6c3215542c0010b1261a44e..22836a86ddbc978ebebd0599080fada2de1fdc1f 100644 (file)
@@ -39,7 +39,8 @@ INCLUDES
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
 #include "FGLGear.h"
-#include <algorithm>
+
+namespace JSBSim {
 
 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 DEFINITIONS
@@ -49,36 +50,23 @@ DEFINITIONS
 GLOBAL DATA
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
-
 static const char *IdSrc = "$Id$";
 static const char *IdHdr = ID_LGEAR;
 
-extern short debug_lvl;
-
 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 CLASS IMPLEMENTATION
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
 
-FGLGear::FGLGear(FGConfigFile* AC_cfg, FGFDMExec* fdmex) : vXYZ(3),
-                                                           vMoment(3),
-                                                           vWhlBodyVec(3),
-                                                           Exec(fdmex)
+FGLGear::FGLGear(FGConfigFile* AC_cfg, FGFDMExec* fdmex, int number) : Exec(fdmex)
 {
   string tmp;
+
+  GearNumber = number;
+
   *AC_cfg >> tmp >> name >> vXYZ(1) >> vXYZ(2) >> vXYZ(3)
             >> kSpring >> bDamp>> dynamicFCoeff >> staticFCoeff
-                  >> rollingFCoeff >> sSteerType >> sBrakeGroup >> maxSteerAngle;
-
-  cout << "    Name: " << name << endl;
-  cout << "      Location: " << vXYZ << endl;
-  cout << "      Spring Constant:  " << kSpring << endl;
-  cout << "      Damping Constant: " << bDamp << endl;
-  cout << "      Dynamic Friction: " << dynamicFCoeff << endl;
-  cout << "      Static Friction:  " << staticFCoeff << endl;
-  cout << "      Rolling Friction: " << rollingFCoeff << endl;
-  cout << "      Steering Type:    " << sSteerType << endl;
-  cout << "      Grouping:         " << sBrakeGroup << endl;
-  cout << "      Max Steer Angle:  " << maxSteerAngle << endl;
+                  >> rollingFCoeff >> sSteerType >> sBrakeGroup
+                     >> maxSteerAngle >> sRetractable;
 
   if      (sBrakeGroup == "LEFT"  ) eBrakeGrp = bgLeft;
   else if (sBrakeGroup == "RIGHT" ) eBrakeGrp = bgRight;
@@ -99,41 +87,70 @@ FGLGear::FGLGear(FGConfigFile* AC_cfg, FGFDMExec* fdmex) : vXYZ(3),
          << sSteerType << " is undefined." << endl;
   }
 
+  if ( sRetractable == "RETRACT" ) {
+    isRetractable = true;
+  } else  {
+    isRetractable = false;
+  }
+
+  GearUp = false;
+  GearDown = true;
+  Servicable = true;
+
 // Add some AI here to determine if gear is located properly according to its
 // brake group type ??
 
   State       = Exec->GetState();
   Aircraft    = Exec->GetAircraft();
-  Position    = Exec->GetPosition();
-  Rotation    = Exec->GetRotation();
+  Propagate   = Exec->GetPropagate();
+  Auxiliary   = Exec->GetAuxiliary();
   FCS         = Exec->GetFCS();
+  MassBalance = Exec->GetMassBalance();
 
-  WOW = false;
+  WOW = lastWOW = true; // should the value be initialized to true?
   ReportEnable = true;
   FirstContact = false;
-  Reported = false;
-  DistanceTraveled = 0.0;
+  StartedGroundRun = false;
+  TakeoffReported = LandingReported = false;
+  LandingDistanceTraveled = TakeoffDistanceTraveled = TakeoffDistanceTraveled50ft = 0.0;
   MaximumStrutForce = MaximumStrutTravel = 0.0;
+  SideForce = RollingForce = 0.0;
+  SinkRate = GroundSpeed = 0.0;
 
-  vWhlBodyVec     = (vXYZ - Aircraft->GetXYZcg()) / 12.0;
-  vWhlBodyVec(eX) = -vWhlBodyVec(eX);
-  vWhlBodyVec(eZ) = -vWhlBodyVec(eZ);
+  vWhlBodyVec = MassBalance->StructuralToBody(vXYZ);
 
-  vLocalGear = State->GetTb2l() * vWhlBodyVec;
+  vLocalGear = Propagate->GetTb2l() * vWhlBodyVec;
 
-  if (debug_lvl & 2) cout << "Instantiated: FGLGear" << endl;
+  compressLength  = 0.0;
+  compressSpeed   = 0.0;
+  brakePct        = 0.0;
+  maxCompLen      = 0.0;
+
+  WheelSlip = lastWheelSlip = 0.0;
+
+  compressLength  = 0.0;
+  compressSpeed   = 0.0;
+  brakePct        = 0.0;
+  maxCompLen      = 0.0;
+
+  TirePressureNorm = 1.0;
+
+  Debug(0);
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 FGLGear::FGLGear(const FGLGear& lgear)
 {
+  GearNumber = lgear.GearNumber;
+
   State    = lgear.State;
   Aircraft = lgear.Aircraft;
-  Position = lgear.Position;
-  Rotation = lgear.Rotation;
+  Propagate = lgear.Propagate;
+  Auxiliary = lgear.Auxiliary;
   Exec     = lgear.Exec;
   FCS      = lgear.FCS;
+  MassBalance = lgear.MassBalance;
 
   vXYZ = lgear.vXYZ;
   vMoment = lgear.vMoment;
@@ -141,11 +158,17 @@ FGLGear::FGLGear(const FGLGear& lgear)
   vLocalGear = lgear.vLocalGear;
 
   WOW                = lgear.WOW;
+  lastWOW            = lgear.lastWOW;
   ReportEnable       = lgear.ReportEnable;
   FirstContact       = lgear.FirstContact;
-  DistanceTraveled   = lgear.DistanceTraveled;
+  StartedGroundRun   = lgear.StartedGroundRun;
+  LandingDistanceTraveled   = lgear.LandingDistanceTraveled;
+  TakeoffDistanceTraveled   = lgear.TakeoffDistanceTraveled;
+  TakeoffDistanceTraveled50ft   = lgear.TakeoffDistanceTraveled50ft;
   MaximumStrutForce  = lgear.MaximumStrutForce;
   MaximumStrutTravel = lgear.MaximumStrutTravel;
+  SideForce          = lgear.SideForce;
+  RollingForce       = lgear.RollingForce;
 
   kSpring         = lgear.kSpring;
   bDamp           = lgear.bDamp;
@@ -158,55 +181,95 @@ FGLGear::FGLGear(const FGLGear& lgear)
   maxCompLen      = lgear.maxCompLen;
   SinkRate        = lgear.SinkRate;
   GroundSpeed     = lgear.GroundSpeed;
-  Reported        = lgear.Reported;
+  LandingReported = lgear.LandingReported;
+  TakeoffReported = lgear.TakeoffReported;
   name            = lgear.name;
   sSteerType      = lgear.sSteerType;
+  sRetractable    = lgear.sRetractable;
   eSteerType      = lgear.eSteerType;
   sBrakeGroup     = lgear.sBrakeGroup;
   eBrakeGrp       = lgear.eBrakeGrp;
   maxSteerAngle   = lgear.maxSteerAngle;
+  isRetractable   = lgear.isRetractable;
+  GearUp          = lgear.GearUp;
+  GearDown        = lgear.GearDown;
+  WheelSlip       = lgear.WheelSlip;
+  lastWheelSlip   = lgear.lastWheelSlip;
+  TirePressureNorm = lgear.TirePressureNorm;
+  Servicable      = lgear.Servicable;
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 FGLGear::~FGLGear()
 {
-  if (debug_lvl & 2) cout << "Destroyed:    FGLGear" << endl;
+  Debug(1);
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-FGColumnVector FGLGear::Force(void)
+FGColumnVector3& FGLGear::Force(void)
 {
-  float SteerGain, SteerAngle, BrakeFCoeff;
-  float SinWheel, CosWheel, SideWhlVel, RollingWhlVel;
-  float RudderPedal, RollingForce, SideForce, FCoeff;
-  float WheelSlip;
+  double SinWheel, CosWheel;
+  double deltaT = State->Getdt()*Aircraft->GetRate();
+
+  vForce.InitMatrix();
+  vMoment.InitMatrix();
+
+  if (isRetractable) {
+    if (FCS->GetGearPos() < 0.01) {
+      GearUp   = true;
+      GearDown = false;
+     } else if (FCS->GetGearPos() > 0.99) {
+      GearDown = true;
+      GearUp   = false;
+     } else {
+      GearUp   = false;
+      GearDown = false;
+     }
+  } else {
+      GearUp   = false;
+      GearDown = true;
+  }
 
-  FGColumnVector vForce(3);
-  FGColumnVector vLocalForce(3);
-  FGColumnVector vWhlVelVec(3);     // Velocity of this wheel (Local)
+  // Compute the steering angle in any case.
+  // Will make shure that animations will look right.
+  switch (eSteerType) {
+  case stSteer:
+    SteerAngle = degtorad * FCS->GetSteerPosDeg(GearNumber);
+    break;
+  case stFixed:
+    SteerAngle = 0.0;
+    break;
+  case stCaster:
+    // Note to Jon: This is not correct for castering gear.  I'll fix it later.
+    SteerAngle = 0.0;
+    break;
+  default:
+    cerr << "Improper steering type membership detected for this gear." << endl;
+    break;
+  }
 
-  vWhlBodyVec     = (vXYZ - Aircraft->GetXYZcg()) / 12.0;
-  vWhlBodyVec(eX) = -vWhlBodyVec(eX);
-  vWhlBodyVec(eZ) = -vWhlBodyVec(eZ);
+  if (GearDown) {
+
+    vWhlBodyVec = MassBalance->StructuralToBody(vXYZ);
 
 // vWhlBodyVec now stores the vector from the cg to this wheel
 
-  vLocalGear = State->GetTb2l() * vWhlBodyVec;
+    vLocalGear = Propagate->GetTb2l() * vWhlBodyVec;
 
 // vLocalGear now stores the vector from the cg to the wheel in local coords.
 
-  compressLength = vLocalGear(eZ) - Position->GetDistanceAGL();
+    compressLength = vLocalGear(eZ) - Propagate->GetDistanceAGL();
 
 // The compression length is currently measured in the Z-axis, only, at this time.
 // It should be measured along the strut axis. If the local-frame gear position
 // "hangs down" below the CG greater than the altitude, then the compressLength
 // will be positive - i.e. the gear will have made contact.
 
-  if (compressLength > 0.00) {
+    if (compressLength > 0.00) {
 
-    WOW = true; // Weight-On-Wheels is true
+      WOW = true; // Weight-On-Wheels is true
 
 // The next equation should really use the vector to the contact patch of the tire
 // including the strut compression and not vWhlBodyVec.  Will fix this later.
@@ -219,19 +282,31 @@ FGColumnVector FGLGear::Force(void)
 // (used for calculating damping force) is found by taking the Z-component of the
 // wheel velocity.
 
-    vWhlVelVec      =  State->GetTb2l() * (Rotation->GetPQR() * vWhlBodyVec);
-    vWhlVelVec     +=  Position->GetVel();
-
-    compressSpeed   =  vWhlVelVec(eZ);
+      vWhlVelVec      =  Propagate->GetTb2l() * (Propagate->GetPQR() * vWhlBodyVec);
+      vWhlVelVec     +=  Propagate->GetVel();
+      compressSpeed   =  vWhlVelVec(eZ);
 
 // If this is the first time the wheel has made contact, remember some values
 // for later printout.
 
-    if (!FirstContact) {
-      FirstContact  = true;
-      SinkRate      =  compressSpeed;
-      GroundSpeed   =  Position->GetVel().Magnitude();
-    }
+      if (!FirstContact) {
+        FirstContact  = true;
+        SinkRate      =  compressSpeed;
+        GroundSpeed   =  Propagate->GetVel().Magnitude();
+        TakeoffReported = false;
+      }
+
+// If the takeoff run is starting, initialize.
+
+      if ((Propagate->GetVel().Magnitude() > 0.1) &&
+          (FCS->GetBrake(bgLeft) == 0) &&
+          (FCS->GetBrake(bgRight) == 0) &&
+          (FCS->GetThrottlePos(0) == 1) && !StartedGroundRun)
+      {
+        TakeoffDistanceTraveled = 0;
+        TakeoffDistanceTraveled50ft = 0;
+        StartedGroundRun = true;
+      }
 
 // The following needs work regarding friction coefficients and braking and
 // steering The BrakeFCoeff formula assumes that an anti-skid system is used.
@@ -240,117 +315,121 @@ FGColumnVector FGLGear::Force(void)
 // [JSB] The braking force coefficients include normal rolling coefficient +
 // a percentage of the static friction coefficient based on braking applied.
 
-    switch (eBrakeGrp) {
-    case bgLeft:
-      SteerGain = -maxSteerAngle;
-      BrakeFCoeff = rollingFCoeff*(1.0 - FCS->GetBrake(bgLeft)) +
-                                            staticFCoeff*FCS->GetBrake(bgLeft);
-      break;
-    case bgRight:
-      SteerGain = -maxSteerAngle;
-      BrakeFCoeff = rollingFCoeff*(1.0 - FCS->GetBrake(bgRight)) +
-                                           staticFCoeff*FCS->GetBrake(bgRight);
-      break;
-    case bgCenter:
-      SteerGain = -maxSteerAngle;
-      BrakeFCoeff = rollingFCoeff*(1.0 - FCS->GetBrake(bgCenter)) +
-                                           staticFCoeff*FCS->GetBrake(bgCenter);
-      break;
-    case bgNose:
-      SteerGain = maxSteerAngle;
-      BrakeFCoeff = rollingFCoeff;
-      break;
-    case bgTail:
-      SteerGain = -maxSteerAngle;
-      BrakeFCoeff = rollingFCoeff;
-      break;
-    case bgNone:
-      SteerGain = -maxSteerAngle;
-      BrakeFCoeff = rollingFCoeff;
-      break;
-    default:
-      cerr << "Improper brake group membership detected for this gear." << endl;
-      break;
-    }
-
-    switch (eSteerType) {
-    case stSteer:
-      SteerAngle = SteerGain*FCS->GetDrCmd();
-      break;
-    case stFixed:
-      SteerAngle = 0.0;
-      break;
-    case stCaster:
-    // Note to Jon: This is not correct for castering gear.  I'll fix it later.
-      SteerAngle = 0.0;
-      break;
-    default:
-      cerr << "Improper steering type membership detected for this gear." << endl;
-      break;
-    }
+      switch (eBrakeGrp) {
+      case bgLeft:
+         BrakeFCoeff = ( rollingFCoeff*(1.0 - FCS->GetBrake(bgLeft)) +
+                        staticFCoeff*FCS->GetBrake(bgLeft) );
+        break;
+      case bgRight:
+        BrakeFCoeff =  ( rollingFCoeff*(1.0 - FCS->GetBrake(bgRight)) +
+                         staticFCoeff*FCS->GetBrake(bgRight) );
+        break;
+      case bgCenter:
+        BrakeFCoeff =  ( rollingFCoeff*(1.0 - FCS->GetBrake(bgCenter)) +
+                         staticFCoeff*FCS->GetBrake(bgCenter) );
+        break;
+      case bgNose:
+        BrakeFCoeff =  ( rollingFCoeff*(1.0 - FCS->GetBrake(bgCenter)) +
+                         staticFCoeff*FCS->GetBrake(bgCenter) );
+        break;
+      case bgTail:
+        BrakeFCoeff =  ( rollingFCoeff*(1.0 - FCS->GetBrake(bgCenter)) +
+                         staticFCoeff*FCS->GetBrake(bgCenter) );
+        break;
+      case bgNone:
+        BrakeFCoeff =  rollingFCoeff;
+        break;
+      default:
+        cerr << "Improper brake group membership detected for this gear." << endl;
+        break;
+      }
 
 // Transform the wheel velocities from the local axis system to the wheel axis system.
 // For now, steering angle is assumed to happen in the Local Z axis,
 // not the strut axis as it should be.  Will fix this later.
 
-    SinWheel      = sin(Rotation->Getpsi() + SteerAngle*DEGTORAD);
-    CosWheel      = cos(Rotation->Getpsi() + SteerAngle*DEGTORAD);
-    RollingWhlVel = vWhlVelVec(eX)*CosWheel + vWhlVelVec(eY)*SinWheel;
-    SideWhlVel    = vWhlVelVec(eY)*CosWheel - vWhlVelVec(eX)*SinWheel;
+      SinWheel      = sin(Propagate->GetEuler(ePsi) + SteerAngle);
+      CosWheel      = cos(Propagate->GetEuler(ePsi) + SteerAngle);
+      RollingWhlVel = vWhlVelVec(eX)*CosWheel + vWhlVelVec(eY)*SinWheel;
+      SideWhlVel    = vWhlVelVec(eY)*CosWheel - vWhlVelVec(eX)*SinWheel;
 
 // Calculate tire slip angle.
 
-    if (RollingWhlVel == 0.0 && SideWhlVel == 0.0) {
-      WheelSlip = 0.0;
-    } else {
-      WheelSlip = RADTODEG*atan2(SideWhlVel, RollingWhlVel);
-    }
-
-// The following code normalizes the wheel velocity vector, reverses it, and zeroes out
-// the z component of the velocity. The question is, should the Z axis velocity be zeroed
-// out first before the normalization takes place or not? Subsequent to that, the Wheel
-// Velocity vector now points as a unit vector backwards and parallel to the wheel
-// velocity vector. It acts AT the wheel.
-
-// Note to Jon: I commented out this line because I wasn't sure we want to do this.
-//    vWhlVelVec      = -1.0 * vWhlVelVec.Normalize();
-//    vWhlVelVec(eZ)  =  0.00;
+      if (RollingWhlVel == 0.0 && SideWhlVel == 0.0) {
+        WheelSlip = 0.0;
+      } else if (fabs(RollingWhlVel) < 1.0) {
+        WheelSlip = 0.05*radtodeg*atan2(SideWhlVel, fabs(RollingWhlVel)) + 0.95*WheelSlip;
+      } else {
+        WheelSlip = radtodeg*atan2(SideWhlVel, fabs(RollingWhlVel));
+      }
+/*
+      double maxdeltaSlip = 0.5*deltaT;
+
+      if (RollingWhlVel == 0.0 && SideWhlVel == 0.0) {
+        WheelSlip = 0.0;
+      } else if (RollingWhlVel < 1.0) {
+        WheelSlip = radtodeg*atan2(SideWhlVel, RollingWhlVel);
+        deltaSlip = WheelSlip - lastWheelSlip;
+        if (fabs(deltaSlip) > maxdeltaSlip) {
+          if (WheelSlip > lastWheelSlip) {
+            WheelSlip = lastWheelSlip + maxdeltaSlip;
+          } else if (WheelSlip < lastWheelSlip) {
+            WheelSlip = lastWheelSlip - maxdeltaSlip;
+          }
+        }
+      } else {
+        WheelSlip = radtodeg*atan2(SideWhlVel, RollingWhlVel);
+      }
+
+      if ((WheelSlip < 0.0 && lastWheelSlip > 0.0) ||
+          (WheelSlip > 0.0 && lastWheelSlip < 0.0))
+      {
+        WheelSlip = 0.0;
+      }
+*/
+      lastWheelSlip = WheelSlip;
 
 // Compute the sideforce coefficients using similar assumptions to LaRCSim for now.
 // Allow a maximum of 10 degrees tire slip angle before wheel slides.  At that point,
 // transition from static to dynamic friction.  There are more complicated formulations
-// of this that avoid the discrete jump.  Will fix this later.
-
-    if (fabs(WheelSlip) <= 10.0) {
-      FCoeff = staticFCoeff*WheelSlip/10.0;
-    } else {
-      FCoeff = dynamicFCoeff*fabs(WheelSlip)/WheelSlip;
-    }
+// of this that avoid the discrete jump (similar to Pacejka).  Will fix this later.
+
+      if (fabs(WheelSlip) <= 20.0) {
+        FCoeff = staticFCoeff*WheelSlip/20.0;
+      } else if (fabs(WheelSlip) <= 40.0) {
+//        FCoeff = dynamicFCoeff*fabs(WheelSlip)/WheelSlip;
+        FCoeff = (dynamicFCoeff*(fabs(WheelSlip) - 20.0)/20.0 +
+                  staticFCoeff*(40.0 - fabs(WheelSlip))/20.0)*fabs(WheelSlip)/WheelSlip;
+      } else {
+        FCoeff = dynamicFCoeff*fabs(WheelSlip)/WheelSlip;
+      }
 
 // Compute the vertical force on the wheel using square-law damping (per comment
 // in paper AIAA-2000-4303 - see header prologue comments). We might consider
 // allowing for both square and linear damping force calculation. Also need to
 // possibly give a "rebound damping factor" that differs from the compression
-// case. NOTE: SQUARE LAW DAMPING NO GOOD!
+// case.
 
-    vLocalForce(eZ) =  min(-compressLength * kSpring
-                           - compressSpeed * bDamp, (float)0.0);
+      vLocalForce(eZ) =  min(-compressLength * kSpring
+                             - compressSpeed * bDamp, (double)0.0);
 
-    MaximumStrutForce = max(MaximumStrutForce, fabs(vLocalForce(eZ)));
-    MaximumStrutTravel = max(MaximumStrutTravel, fabs(compressLength));
+      MaximumStrutForce = max(MaximumStrutForce, fabs(vLocalForce(eZ)));
+      MaximumStrutTravel = max(MaximumStrutTravel, fabs(compressLength));
 
 // Compute the forces in the wheel ground plane.
 
-    RollingForce = 0;
-    if (fabs(RollingWhlVel) > 1E-3) {
-      RollingForce = vLocalForce(eZ) * BrakeFCoeff * fabs(RollingWhlVel)/RollingWhlVel;
-    }
-    SideForce    = vLocalForce(eZ) * FCoeff;
+      RollingForce = 0;
+      if (fabs(RollingWhlVel) > 1E-3) {
+        RollingForce = (1.0 - TirePressureNorm) * 30
+                       + vLocalForce(eZ) * BrakeFCoeff
+                       * fabs(RollingWhlVel)/RollingWhlVel;
+      }
+      SideForce    = vLocalForce(eZ) * FCoeff;
 
 // Transform these forces back to the local reference frame.
 
-    vLocalForce(eX) = RollingForce*CosWheel - SideForce*SinWheel;
-    vLocalForce(eY) = SideForce*CosWheel    + RollingForce*SinWheel;
+      vLocalForce(eX) = RollingForce*CosWheel - SideForce*SinWheel;
+      vLocalForce(eY) = SideForce*CosWheel    + RollingForce*SinWheel;
 
 // Note to Jon: At this point the forces will be too big when the airplane is
 // stopped or rolling to a stop.  We need to make sure that the gear forces just
@@ -366,57 +445,149 @@ FGColumnVector FGLGear::Force(void)
 
 // Transform the forces back to the body frame and compute the moment.
 
-    vForce  = State->GetTl2b() * vLocalForce;
-    vMoment = vWhlBodyVec * vForce;
+      vForce  = Propagate->GetTl2b() * vLocalForce;
+      vMoment = vWhlBodyVec * vForce;
 
-  } else {
+    } else { // Gear is NOT compressed
+
+      WOW = false;
+
+      // Return to neutral position between 1.0 and 0.8 gear pos.
+      SteerAngle *= max(FCS->GetGearPos()-0.8, 0.0)/0.2;
 
-    WOW = false;
+      if (Propagate->GetDistanceAGL() > 200.0) {
+        FirstContact = false;
+        StartedGroundRun = false;
+        LandingReported = false;
+        LandingDistanceTraveled = 0.0;
+        MaximumStrutForce = MaximumStrutTravel = 0.0;
+      }
 
-    if (Position->GetDistanceAGL() > 200.0) {
-      FirstContact = false;
-      Reported = false;
-      DistanceTraveled = 0.0;
-      MaximumStrutForce = MaximumStrutTravel = 0.0;
+      compressLength = 0.0; // reset compressLength to zero for data output validity
     }
 
-    vForce.InitMatrix();
-    vMoment.InitMatrix();
-  }
+    if (FirstContact) LandingDistanceTraveled += Auxiliary->GetVground()*deltaT;
 
-  if (FirstContact) {
-    DistanceTraveled += Position->GetVel().Magnitude()*State->Getdt()*Aircraft->GetRate();
-  }
+    if (StartedGroundRun) {
+       TakeoffDistanceTraveled50ft += Auxiliary->GetVground()*deltaT;
+      if (WOW) TakeoffDistanceTraveled += Auxiliary->GetVground()*deltaT;
+    }
 
-  if (ReportEnable && Position->GetVel().Magnitude() <= 0.05 && !Reported) {
-    Report();
-  }
+    if (ReportEnable && Auxiliary->GetVground() <= 0.05 && !LandingReported) {
+      if (debug_lvl > 0) Report(erLand);
+    }
+
+    if (ReportEnable && !TakeoffReported &&
+       (vLocalGear(eZ) - Propagate->GetDistanceAGL()) < -50.0)
+    {
+      if (debug_lvl > 0) Report(erTakeoff);
+    }
+
+    if (lastWOW != WOW) {
+      PutMessage("GEAR_CONTACT: " + name, WOW);
+    }
+
+    lastWOW = WOW;
 
+// Crash detection logic (really out-of-bounds detection)
+
+    if (compressLength > 500.0 ||
+        vForce.Magnitude() > 100000000.0 ||
+        vMoment.Magnitude() > 5000000000.0 ||
+        SinkRate > 1.4666*30)
+    {
+      PutMessage("Crash Detected: Simulation FREEZE.");
+      Exec->Freeze();
+    }
+  }
   return vForce;
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
-void FGLGear::Report(void)
+void FGLGear::Report(ReportType repType)
 {
-  cout << endl << "Touchdown report for " << name << endl;
-  cout << "  Sink rate at contact:  " << SinkRate                << " fps,    "
-                              << SinkRate*0.3408          << " mps"     << endl;
-  cout << "  Contact ground speed:  " << GroundSpeed*.5925       << " knots,  "
-                              << GroundSpeed*0.3408       << " mps"     << endl;
-  cout << "  Maximum contact force: " << MaximumStrutForce       << " lbs,    "
-                              << MaximumStrutForce*4.448  << " Newtons" << endl;
-  cout << "  Maximum strut travel:  " << MaximumStrutTravel*12.0 << " inches, "
-                              << MaximumStrutTravel*30.48 << " cm"      << endl;
-  cout << "  Distance traveled:     " << DistanceTraveled        << " ft,     "
-                              << DistanceTraveled*0.3408  << " meters"  << endl;
-  Reported = true;
+  switch(repType) {
+  case erLand:
+    cout << endl << "Touchdown report for " << name << endl;
+    cout << "  Sink rate at contact:  " << SinkRate                << " fps,    "
+                                << SinkRate*0.3048          << " mps"     << endl;
+    cout << "  Contact ground speed:  " << GroundSpeed*.5925       << " knots,  "
+                                << GroundSpeed*0.3048       << " mps"     << endl;
+    cout << "  Maximum contact force: " << MaximumStrutForce       << " lbs,    "
+                                << MaximumStrutForce*4.448  << " Newtons" << endl;
+    cout << "  Maximum strut travel:  " << MaximumStrutTravel*12.0 << " inches, "
+                                << MaximumStrutTravel*30.48 << " cm"      << endl;
+    cout << "  Distance traveled:     " << LandingDistanceTraveled        << " ft,     "
+                                << LandingDistanceTraveled*0.3048  << " meters"  << endl;
+    LandingReported = true;
+    break;
+  case erTakeoff:
+    cout << endl << "Takeoff report for " << name << endl;
+    cout << "  Distance traveled:                " << TakeoffDistanceTraveled
+         << " ft,     " << TakeoffDistanceTraveled*0.3048  << " meters"  << endl;
+    cout << "  Distance traveled (over 50'):     " << TakeoffDistanceTraveled50ft
+         << " ft,     " << TakeoffDistanceTraveled50ft*0.3048 << " meters" << endl;
+    TakeoffReported = true;
+    break;
+  }
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-
-void FGLGear::Debug(void)
+//    The bitmasked value choices are as follows:
+//    unset: In this case (the default) JSBSim would only print
+//       out the normally expected messages, essentially echoing
+//       the config files as they are read. If the environment
+//       variable is not set, debug_lvl is set to 1 internally
+//    0: This requests JSBSim not to output any messages
+//       whatsoever.
+//    1: This value explicity requests the normal JSBSim
+//       startup messages
+//    2: This value asks for a message to be printed out when
+//       a class is instantiated
+//    4: When this value is set, a message is displayed when a
+//       FGModel object executes its Run() method
+//    8: When this value is set, various runtime state variables
+//       are printed out periodically
+//    16: When set various parameters are sanity checked and
+//       a message is printed out when they go out of bounds
+
+void FGLGear::Debug(int from)
 {
-  // TODO: Add user code here
+  if (debug_lvl <= 0) return;
+
+  if (debug_lvl & 1) { // Standard console startup message output
+    if (from == 0) { // Constructor
+      cout << "    Name: "               << name          << endl;
+      cout << "      Location: "         << vXYZ          << endl;
+      cout << "      Spring Constant:  " << kSpring       << endl;
+      cout << "      Damping Constant: " << bDamp         << endl;
+      cout << "      Dynamic Friction: " << dynamicFCoeff << endl;
+      cout << "      Static Friction:  " << staticFCoeff  << endl;
+      cout << "      Rolling Friction: " << rollingFCoeff << endl;
+      cout << "      Steering Type:    " << sSteerType    << endl;
+      cout << "      Grouping:         " << sBrakeGroup   << endl;
+      cout << "      Max Steer Angle:  " << maxSteerAngle << endl;
+      cout << "      Retractable:      " << sRetractable  << endl;
+    }
+  }
+  if (debug_lvl & 2 ) { // Instantiation/Destruction notification
+    if (from == 0) cout << "Instantiated: FGLGear" << endl;
+    if (from == 1) cout << "Destroyed:    FGLGear" << endl;
+  }
+  if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
+  }
+  if (debug_lvl & 8 ) { // Runtime state variables
+  }
+  if (debug_lvl & 16) { // Sanity checking
+  }
+  if (debug_lvl & 64) {
+    if (from == 0) { // Constructor
+      cout << IdSrc << endl;
+      cout << IdHdr << endl;
+    }
+  }
 }
 
+} // namespace JSBSim
+