From be71e0f555c87799f405e6ce4c9d8e70d41fd5f9 Mon Sep 17 00:00:00 2001
From: tony <tony>
Date: Sat, 4 May 2002 17:38:06 +0000
Subject: [PATCH] Added stall hysteresis modeling, nose should fall through
 nicely in a stall now.

---
 src/FDM/JSBSim/FGAircraft.cpp | 30 ++++++++++++++++++++++++++----
 src/FDM/JSBSim/FGAircraft.h   |  8 +++++++-
 src/FDM/JSBSim/FGJSBBase.h    |  3 ++-
 src/FDM/JSBSim/FGState.cpp    |  1 +
 4 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/src/FDM/JSBSim/FGAircraft.cpp b/src/FDM/JSBSim/FGAircraft.cpp
index 073afba3d..a84cc09d0 100644
--- a/src/FDM/JSBSim/FGAircraft.cpp
+++ b/src/FDM/JSBSim/FGAircraft.cpp
@@ -103,8 +103,9 @@ FGAircraft::FGAircraft(FGFDMExec* fdmex) : FGModel(fdmex)
 {
   Name = "FGAircraft";
   WingIncidence   = 0.0;
-  impending_stall = 0.0;
+  impending_stall = stall_hyst = 0.0;
   alphaclmin = alphaclmax = 0.0;
+  alphahystmin = alphahystmax = 0.0;
   HTailArea = VTailArea = 0.0;
   HTailArm  = VTailArm  = 0.0;
   lbarh = lbarv = 0.0;
@@ -130,6 +131,7 @@ FGAircraft::~FGAircraft()
 bool FGAircraft::Run(void)
 {
   double twovel;
+  double alpha;
   
   if (!FGModel::Run()) {                 // if false then execute this Run()
     vForces.InitMatrix();
@@ -158,13 +160,25 @@ bool FGAircraft::Run(void)
     
     alphaw = Translation->Getalpha() + WingIncidence;
     
+    alpha=Translation->Getalpha();
+    
     if (alphaclmax != 0) {
-      if (Translation->Getalpha() > 0.85*alphaclmax) {
-        impending_stall = 10*(Translation->Getalpha()/alphaclmax - 0.85);
+      if (alpha > 0.85*alphaclmax) {
+        impending_stall = 10*(alpha/alphaclmax - 0.85);
       } else {
         impending_stall = 0;
       }
-    }      
+          
+    }   
+    if(alphahystmax != 0.0 && alphahystmin != 0.0) {
+          if( alpha > alphahystmax ) {
+            stall_hyst = 1;
+          } else if(alpha < alphahystmin) {
+            stall_hyst = 0;
+          }    
+    }
+
+     
     
     return false;
   } else {                               // skip Run() execution this time
@@ -256,6 +270,11 @@ bool FGAircraft::Load(FGConfigFile* AC_cfg)
       if (debug_lvl > 0) cout << "    Maximum Alpha: " << alphaclmax
              << "    Minimum Alpha: " << alphaclmin
              << endl;
+    } else if (parameter == "AC_HYSTLIMITS") {
+      *AC_cfg >> alphahystmin >> alphahystmax;
+      if (debug_lvl > 0) cout << "    Hysteresis Start: " << alphahystmax
+             << "    Hysteresis End: " << alphahystmin
+             << endl;
     } else if (parameter == "AC_POINTMASS") {
       *AC_cfg >> pmWt >> pmX >> pmY >> pmZ;
       MassBalance->AddPointMass(pmWt, pmX, pmY, pmZ);
@@ -346,6 +365,9 @@ void FGAircraft::bind(void)
                        &FGAircraft::GetAlphaW);
   PropertyManager->Tie("systems/stall-warn-norm", this,
                         &FGAircraft::GetStallWarn);
+  PropertyManager->Tie("aero/stall-hyst-norm", this,
+                        &FGAircraft::GetHysteresisParm);
+                        
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
diff --git a/src/FDM/JSBSim/FGAircraft.h b/src/FDM/JSBSim/FGAircraft.h
index 8438aba13..891ec53b8 100644
--- a/src/FDM/JSBSim/FGAircraft.h
+++ b/src/FDM/JSBSim/FGAircraft.h
@@ -160,6 +160,11 @@ public:
   inline double GetXYZep(int idx) const { return vXYZep(idx); }
   inline double GetAlphaCLMax(void) const { return alphaclmax; }
   inline double GetAlphaCLMin(void) const { return alphaclmin; }
+  
+  inline double GetAlphaHystMax(void) const { return alphahystmax; }
+  inline double GetAlphaHystMin(void) const { return alphahystmin; }
+  inline double GetHysteresisParm(void) const { return stall_hyst; }
+  
 
   inline void SetAlphaCLMax(double tt) { alphaclmax=tt; }
   inline void SetAlphaCLMin(double tt) { alphaclmin=tt; }
@@ -193,7 +198,8 @@ private:
   double HTailArea, VTailArea, HTailArm, VTailArm;
   double lbarh,lbarv,vbarh,vbarv;
   double alphaclmax,alphaclmin;
-  double impending_stall;
+  double alphahystmax, alphahystmin;
+  double impending_stall, stall_hyst;
   double bi2vel, ci2vel,alphaw;
   string AircraftName;
 
diff --git a/src/FDM/JSBSim/FGJSBBase.h b/src/FDM/JSBSim/FGJSBBase.h
index d7349476b..8a6de13ca 100644
--- a/src/FDM/JSBSim/FGJSBBase.h
+++ b/src/FDM/JSBSim/FGJSBBase.h
@@ -164,7 +164,8 @@ enum eParam {
   FG_VBARH,    //horizontal tail volume 
   FG_VBARV,     //vertical tail volume 
   FG_GEAR_CMD,
-  FG_GEAR_POS
+  FG_GEAR_POS,
+  FG_HYSTPARM
 };
 
 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
diff --git a/src/FDM/JSBSim/FGState.cpp b/src/FDM/JSBSim/FGState.cpp
index 956922022..850d8812b 100644
--- a/src/FDM/JSBSim/FGState.cpp
+++ b/src/FDM/JSBSim/FGState.cpp
@@ -575,6 +575,7 @@ void FGState::InitPropertyMaps(void)
   ParamNameToProp[  "FG_VBARV" ]="metrics/vbarv-norm";     
   ParamNameToProp[  "FG_GEAR_CMD" ]="gear/gear-cmd-norm";
   ParamNameToProp[  "FG_GEAR_POS" ]="gear/gear-pos-norm";
+  ParamNameToProp[  "FG_HYSTPARM" ]="aero/stall-hyst-norm";
 }
 
 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-- 
2.39.5