From 5bbd649b5ab28567cbe0b814c7d6822fdf1242cb Mon Sep 17 00:00:00 2001
From: mfranz <mfranz>
Date: Tue, 15 May 2007 21:30:33 +0000
Subject: [PATCH] Maik JUSTUS: "further (final?) modifications for the jet
 ranger rotor"

---
 src/FDM/YASim/Rotor.cpp     | 4 ++++
 src/FDM/YASim/Rotor.hpp     | 3 ++-
 src/FDM/YASim/Rotorpart.cpp | 7 ++++---
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/FDM/YASim/Rotor.cpp b/src/FDM/YASim/Rotor.cpp
index 0b132772e..371139189 100644
--- a/src/FDM/YASim/Rotor.cpp
+++ b/src/FDM/YASim/Rotor.cpp
@@ -3,6 +3,7 @@
 #include "Math.hpp"
 #include "Surface.hpp"
 #include "Rotorpart.hpp"
+#include "Glue.hpp"
 #include "Ground.hpp"
 #include "Rotor.hpp"
 
@@ -695,6 +696,9 @@ void Rotor::calcLiftFactor(float* v, float rho, State *s)
         *(_translift_maxfactor-1)+1)/_translift_maxfactor;
 
     _lift_factor = _f_ge*_f_tl*_f_vs;
+
+    //store the gravity direction
+    Glue::geodUp(s->pos, _grav_direction);
 }
 
 void Rotor::findGroundEffectAltitude(Ground * ground_cb,State *s)
diff --git a/src/FDM/YASim/Rotor.hpp b/src/FDM/YASim/Rotor.hpp
index 379a36a7b..1b326415e 100644
--- a/src/FDM/YASim/Rotor.hpp
+++ b/src/FDM/YASim/Rotor.hpp
@@ -113,9 +113,9 @@ public:
     float getOverallStall() 
         {if (_stall_v2sum !=0 ) return _stall_sum/_stall_v2sum; else return 0;}
     float getAirfoilIncidenceNoLift() {return _airfoil_incidence_no_lift;}
-
     Vector _rotorparts;
     void findGroundEffectAltitude(Ground * ground_cb,State *s);
+    float *getGravDirection() {return _grav_direction;}
     void writeInfo();
     void setSharedFlapHinge(bool s);
 
@@ -201,6 +201,7 @@ private:
     float _rotor_correction_factor;
     float _phi;
     bool _shared_flap_hinge;
+    float _grav_direction[3];
 };
 std::ostream &  operator<<(std::ostream & out, /*const*/ Rotor& r);
 
diff --git a/src/FDM/YASim/Rotorpart.cpp b/src/FDM/YASim/Rotorpart.cpp
index 450f93f14..417904c9c 100644
--- a/src/FDM/YASim/Rotorpart.cpp
+++ b/src/FDM/YASim/Rotorpart.cpp
@@ -361,7 +361,8 @@ float Rotorpart::calculateAlpha(float* v_rel_air, float rho,
     int i,n;
     for (i=0;i<3;i++)
         moment[i]=0;
-    lift_moment=-_mass*_len*9.81; //*cos yaw * cos roll
+    float relgrav = Math::dot3(_normal,_rotor->getGravDirection());
+    lift_moment=-_mass*_len*9.81*relgrav;
     *torque=0;//
     if((_nextrp==NULL)||(_lastrp==NULL)||(_rotor==NULL)) 
         return 0.0;//not initialized. Can happen during startupt of flightgear
@@ -453,12 +454,12 @@ float Rotorpart::calculateAlpha(float* v_rel_air, float rho,
     {
         float div=0;
         if (Math::abs(_alphaalt) >1e-6)
-            div=(_centripetalforce * _len - _mass * _len * 9.81 /_alpha0*(_alphaalt+_oppositerp->getAlphaAlt())/(2.0*_alphaalt));
+            div=(_centripetalforce * _len - _mass * _len * 9.81 * relgrav /_alpha0*(_alphaalt+_oppositerp->getAlphaAlt())/(2.0*_alphaalt));
         if (Math::abs(div)>1e-6)
             alpha=lift_moment/div;
         else if(Math::abs(_alphaalt+_oppositerp->getAlphaAlt())>1e-6)
         {
-            float div=(_centripetalforce * _len - _mass * _len * 9.81 *0.5)*(_alphaalt+_oppositerp->getAlphaAlt());
+            float div=(_centripetalforce * _len - _mass * _len * 9.81 *0.5 * relgrav)*(_alphaalt+_oppositerp->getAlphaAlt());
             if (Math::abs(div)>1e-6)
                 alpha=_oppositerp->getAlphaAlt()+lift_moment/div*_alphaalt;
         }