Patches from Tony Peden:

Attached are patches for adding the command line options to set initial
glideslope and climb rate. This was really easy to do as all the pieces
were in place.  It works well with JSBSim because the trimming routine
finds the right throttle and elevator settings. It should work with
LaRCsim as well, but it has no trimming routine so there will be some
dynamics at startup.  I don't know what YASim will do.

src/FDM/JSBSim.cxx

@@ -612,7 +612,12 @@ void FGJSBsim::set_Climb_Rate( double roc) {
     SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Climb_Rate: " << roc );
     
     update_ic();
-    fgic->SetClimbRateFpsIC(roc);
+    //since both climb rate and flight path angle are set in the FG
+    //startup sequence, something is needed to keep one from cancelling
+    //out the other.
+    if( !(fabs(roc) > 1 && fabs(fgic->GetFlightPathAngleRadIC()) < 0.01) ) {
+      fgic->SetClimbRateFpsIC(roc);
+    }  
     needTrim=true;
 }
 
@@ -620,7 +625,9 @@ void FGJSBsim::set_Gamma_vert_rad( double gamma) {
     SG_LOG(SG_FLIGHT,SG_INFO, "FGJSBsim::set_Gamma_vert_rad: " << gamma );
     
     update_ic();
-    fgic->SetFlightPathAngleRadIC(gamma);
+    if( !(fabs(gamma) < 0.01 && fabs(fgic->GetClimbRateFpsIC()) > 1) ) {
+      fgic->SetFlightPathAngleRadIC(gamma);
+    }  
     needTrim=true;
 }
 

src/FDM/flight.cxx

@@ -351,7 +351,11 @@ FGInterface::bind ()
 
 				// Climb and slip (read-only)
   fgTie("/velocities/vertical-speed-fps", this,
-	&FGInterface::get_Climb_Rate); // read-only
+	&FGInterface::get_Climb_Rate,
+  &FGInterface::set_Climb_Rate ); 
+  fgTie("/velocities/glideslope", this,
+  &FGInterface::get_Gamma_vert_rad,
+  &FGInterface::set_Gamma_vert_rad );
   fgTie("/velocities/side-slip-rad", this,
 	&FGInterface::get_Beta); // read-only
   fgTie("/velocities/side-slip-deg", this,
@@ -360,8 +364,6 @@ FGInterface::bind ()
   &FGInterface::get_Alpha_deg); // read-only
   fgTie("/accelerations/nlf", this,
   &FGInterface::get_Nlf); // read-only
-  
-  
 }
 
 
@@ -395,6 +397,7 @@ FGInterface::unbind ()
   fgUntie("/velocities/vBody-fps");
   fgUntie("/velocities/wBody-fps");
   fgUntie("/velocities/vertical-speed-fps");
+  fgUntie("/velocities/glideslope");
   fgUntie("/velocities/side-slip-rad");
   fgUntie("/velocities/side-slip-deg");
   fgUntie("/velocities/alpha-deg");

src/Main/options.cxx

@@ -666,6 +666,11 @@ parse_option (const string& arg)
 	fgSetDouble("/orientation/roll-deg", atof(arg.substr(7)));
     } else if ( arg.find( "--pitch=" ) == 0 ) {
 	fgSetDouble("/orientation/pitch-deg", atof(arg.substr(8)));
+    } else if ( arg.find( "--glideslope=" ) == 0 ) {
+	fgSetDouble("/velocities/glideslope", atof(arg.substr(13))
+                                          *SG_DEGREES_TO_RADIANS);
+    }  else if ( arg.find( "--roc=" ) == 0 ) {
+	fgSetDouble("/velocities/vertical-speed-fps", atof(arg.substr(6))/60);
     } else if ( arg.find( "--fg-root=" ) == 0 ) {
 	globals->set_fg_root(arg.substr( 10 ));
     } else if ( arg.find( "--fg-scenery=" ) == 0 ) {
@@ -1181,6 +1186,8 @@ fgUsage ()
          << "                                  (in feet unless --units-meters specified)" << endl
          << "    --vc=knots                    Specify initial airspeed" << endl
          << "    --mach=num                    Specify initial mach number" << endl
+         << "    --glideslope=degreees         Specify flight path angle (can be positive)" << endl
+         << "    --roc=fpm                     Specify initial climb rate (can be negative)" << endl
          << endl
 
          << "Rendering Options:" << endl