resync JSBSim

[flightgear.git] / src / FDM / LaRCsim / c172_engine.c

diff --git a/src/FDM/LaRCsim/c172_engine.c b/src/FDM/LaRCsim/c172_engine.c
index 2b738dae151855ff537aa6104fb16059c13223df..64632a2d103557b79d4005c0da57f080bd855ff1 100644 (file)
--- a/src/FDM/LaRCsim/c172_engine.c
+++ b/src/FDM/LaRCsim/c172_engine.c
@@ -65,20 +65,40 @@ $Header$
 #include "ls_generic.h"
 #include "ls_sim_control.h"
 #include "ls_cockpit.h"
+#include "c172_aero.h"
 
 extern SIM_CONTROL     sim_control_;
 
-void engine( SCALAR dt, int init ) {
-    /* if (init) { */
+void c172_engine( SCALAR dt, int init ) {
+    
+    float v,h,pa;
+    float bhp=160;
+       
     Throttle[3] = Throttle_pct;
-    /* } */
 
-    /* F_X_engine = Throttle[3]*813.4/0.2; */  /* original code */
-    /* F_Z_engine = Throttle[3]*11.36/0.2; */  /* original code */
-    F_X_engine = Throttle[3]*268.42/0.83;
-    F_Z_engine = Throttle[3]*3.75/0.83;
+    
+    if ( ! Use_External_Engine ) {
+       /* do a crude engine power calc based on throttle position */
+       v=V_rel_wind;
+       h=Altitude;
+       if(V_rel_wind < 10)
+           v=10;
+       if(Altitude < 0)
+           h=0;
+       pa=(0.00144*v + 0.546)*(1 - 1.6E-5*h)*bhp;
+       if(pa < 0)
+           pa=0;
+
+       F_X_engine = Throttle[3]*(pa*550)/v;
+    } else {
+       /* accept external settings */
+    }
+
+    /* printf("F_X_engine = %.3f\n", F_X_engine); */
+
+    M_m_engine = F_X_engine*0.734*cbar;
+    /* 0.734 - estimated (WAGged) location of thrust line in the z-axis*/
 
-    Throttle_pct = Throttle[3];
 }