Make the scenerio's work again (now for real) and a small number of updates.

[flightgear.git] / src / AIModel / AIBase.cxx

diff --git a/src/AIModel/AIBase.cxx b/src/AIModel/AIBase.cxx
index 57a6ed5a322ffed8ee028fc5862082e06eb26eef..935d5c660ac9ee3c0d310f70b69e435da6d53b9e 100644 (file)
--- a/src/AIModel/AIBase.cxx
+++ b/src/AIModel/AIBase.cxx
@@ -43,6 +43,11 @@
 #include "AIBase.hxx"
 #include "AIManager.hxx"
 
+
+const double FGAIBase::e = 2.71828183;
+const double FGAIBase::lbs_to_slugs = 0.031080950172;   //conversion factor
+
+
 FGAIBase::FGAIBase()
  :  fp( NULL ),
     model( NULL ),
@@ -75,6 +80,24 @@ FGAIBase::~FGAIBase() {
 void FGAIBase::update(double dt) {
     ft_per_deg_lat = 366468.96 - 3717.12 * cos(pos.lat()/SG_RADIANS_TO_DEGREES);
     ft_per_deg_lon = 365228.16 * cos(pos.lat() / SG_RADIANS_TO_DEGREES);
+
+    // Calculate rho at altitude, using standard atmosphere
+    // For the temperature T and the pressure p,
+
+    if (altitude < 36152) {            // curve fits for the troposphere
+      T = 59 - 0.00356 * altitude;
+      p = 2116 * pow( ((T + 459.7) / 518.6) , 5.256);
+
+    } else if ( 36152 < altitude && altitude < 82345 ) {    // lower stratosphere
+      T = -70;
+      p = 473.1 * pow( e , 1.73 - (0.000048 * altitude) );
+
+    } else {                                    //  upper stratosphere
+      T = -205.05 + (0.00164 * altitude);
+      p = 51.97 * pow( ((T + 459.7) / 389.98) , -11.388);
+    }
+
+    rho = p / (1718 * (T + 459.7));
 }