flightgear/src/FDM/JSBSim.cxx

// JSBsim.cxx -- interface to the JSBsim flight model
//
// Written by Curtis Olson, started February 1999.
//
// Copyright (C) 1999  Curtis L. Olson  - curt@flightgear.org
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// $Id$


#include <simgear/compiler.h>

#ifdef FG_MATH_EXCEPTION_CLASH
#  include <math.h>
#endif

#include STL_STRING

#include <simgear/constants.h>
#include <simgear/debug/logstream.hxx>
#include <simgear/math/sg_geodesy.hxx>
#include <simgear/misc/fgpath.hxx>

#include <Scenery/scenery.hxx>

#include <Aircraft/aircraft.hxx>
#include <Controls/controls.hxx>
#include <Main/globals.hxx>

#include <FDM/JSBSim/FGFDMExec.h>
#include <FDM/JSBSim/FGAircraft.h>
#include <FDM/JSBSim/FGFCS.h>
#include <FDM/JSBSim/FGPosition.h>
#include <FDM/JSBSim/FGRotation.h>
#include <FDM/JSBSim/FGState.h>
#include <FDM/JSBSim/FGTranslation.h>
#include <FDM/JSBSim/FGAuxiliary.h>
#include <FDM/JSBSim/FGDefs.h>
#include <FDM/JSBSim/FGInitialCondition.h>
#include <FDM/JSBSim/FGTrim.h>
#include <FDM/JSBSim/FGAtmosphere.h>

#include "JSBSim.hxx"

/******************************************************************************/

FGJSBsim::FGJSBsim(void) {
    bool result;
  
    fdmex=new FGFDMExec;
    fgic=new FGInitialCondition(fdmex);
    needTrim=true;
  
    FGPath aircraft_path( globals->get_options()->get_fg_root() );
    aircraft_path.append( "Aircraft" );

    FGPath engine_path( globals->get_options()->get_fg_root() );
    engine_path.append( "Engine" );
    float dt = 1.0 / globals->get_options()->get_model_hz();
    fdmex->GetState()->Setdt( dt );

    result = fdmex->LoadModel( aircraft_path.str(),
			       engine_path.str(),
			       globals->get_options()->get_aircraft() );
    int Neng=fdmex->GetAircraft()->GetNumEngines();
    FG_LOG(FG_FLIGHT,FG_INFO, "Neng: " << Neng );
    for(int i=0;i<Neng;i++) {
	add_engine( FGEngInterface() );
    }  

}

/******************************************************************************/
FGJSBsim::~FGJSBsim(void) {
    if(fdmex != NULL) {
	delete fdmex;
	delete fgic;
    }  
}

/******************************************************************************/

// Initialize the JSBsim flight model, dt is the time increment for
// each subsequent iteration through the EOM

bool FGJSBsim::init( double dt ) {

    bool result;

    FG_LOG( FG_FLIGHT, FG_INFO, "Starting and initializing JSBsim" );

#if 0
    FGPath aircraft_path( globals->get_options()->get_fg_root() );
    aircraft_path.append( "Aircraft" );

    FGPath engine_path( globals->get_options()->get_fg_root() );
    engine_path.append( "Engine" );

    fdmex->GetState()->Setdt( dt );

    result = fdmex->LoadModel( aircraft_path.str(),
			       engine_path.str(),
			       globals->get_options()->get_aircraft() );
#endif

    if (result) {
	FG_LOG( FG_FLIGHT, FG_INFO, "  loaded aircraft " << globals->get_options()->get_aircraft() );
    } else {
	FG_LOG( FG_FLIGHT, FG_INFO, "  aircraft "
		<< globals->get_options()->get_aircraft()
		<< " does not exist" );
	return false;
    }
    
    fdmex->GetAtmosphere()->UseInternal();
  
    FG_LOG( FG_FLIGHT, FG_INFO, "  Initializing JSBSim with:" );
    switch(fgic->GetSpeedSet()) {
    case setned:
	FG_LOG(FG_FLIGHT,FG_INFO, "  Vn,Ve,Vd= " 
	       << fdmex->GetPosition()->GetVn()
	       << ", " << fdmex->GetPosition()->GetVe()
	       << ", " << fdmex->GetPosition()->GetVd()
	       << " ft/s");
	break;       
    case setuvw:
	FG_LOG(FG_FLIGHT,FG_INFO, "  U,V,W= " 
	       << fdmex->GetTranslation()->GetUVW()(1)
	       << ", " << fdmex->GetTranslation()->GetUVW()(2)
	       << ", " << fdmex->GetTranslation()->GetUVW()(3)
	       << " ft/s");
	break;       
    case setmach:
	FG_LOG(FG_FLIGHT,FG_INFO, "  Mach: " 
	       << fdmex->GetTranslation()->GetMach() );
	break;
    case setvc:
    default:
	FG_LOG(FG_FLIGHT,FG_INFO, "  Indicated Airspeed: " 
	       << fdmex->GetAuxiliary()->GetVcalibratedKTS() << " knots" );
      
    }

    //FG_LOG( FG_FLIGHT, FG_INFO, "  gamma: " <<  globals->get_options()->get_Gamma());
    FG_LOG( FG_FLIGHT, FG_INFO, "  Bank Angle: " 
	    <<  fdmex->GetRotation()->Getphi()*RADTODEG << " deg");
    FG_LOG( FG_FLIGHT, FG_INFO, "  Pitch Angle: " 
	    << fdmex->GetRotation()->Gettht()*RADTODEG << " deg"  );
    FG_LOG( FG_FLIGHT, FG_INFO, "  True Heading: " 
	    << fdmex->GetRotation()->Getpsi()*RADTODEG << " deg"  );
    FG_LOG( FG_FLIGHT, FG_INFO, "  Latitude: " 
	    <<  fdmex->GetPosition()->GetLatitude() << " deg" );
    FG_LOG( FG_FLIGHT, FG_INFO, "  Longitude: " 
	    <<  fdmex->GetPosition()->GetLongitude() << " deg"  );
  
    // for debug only
    /* FG_LOG( FG_FLIGHT, FG_DEBUG, "  FGJSBSim::get_Altitude(): " <<  get_Altitude() );
       FG_LOG( FG_FLIGHT, FG_DEBUG, "  FGJSBSim::get_Sea_level_radius(): " << get_Sea_level_radius()  );
       FG_LOG( FG_FLIGHT, FG_DEBUG, "  scenery.cur_radius*METER_TO_FEET: "
       <<  scenery.cur_radius*METER_TO_FEET );
       FG_LOG( FG_FLIGHT, FG_DEBUG, "  Calculated Terrain ASL: " << endl 
       << "    " << "scenery.cur_radius*METER_TO_FEET -get_Sea_level_radius()= " 
       <<  scenery.cur_radius*METER_TO_FEET - get_Sea_level_radius()  );

       FG_LOG( FG_FLIGHT, FG_DEBUG, "  Calculated Aircraft AGL: " << endl 
       << "    " << "get_Altitude() + get_Sea_level_radius() - scenery.cur_radius*METER_TO_FEET= " 
       <<  get_Altitude() + get_Sea_level_radius()- scenery.cur_radius*METER_TO_FEET );
       FG_LOG( FG_FLIGHT, FG_DEBUG, "  globals->get_options()->get_altitude(): " 
       <<  globals->get_options()->get_altitude() );
       FG_LOG( FG_FLIGHT, FG_DEBUG, "  FGBFI::getAltitude(): " 
       <<  FGBFI::getAltitude() );    */


    FG_LOG( FG_FLIGHT, FG_INFO, "  loaded initial conditions" );

    FG_LOG( FG_FLIGHT, FG_INFO, "  set dt" );

    FG_LOG( FG_FLIGHT, FG_INFO, "Finished initializing JSBSim" );

    return true;
}

/******************************************************************************/

// Run an iteration of the EOM (equations of motion)

bool FGJSBsim::update( int multiloop ) {
  
    int i;
  
    double save_alt = 0.0;
 
  
    // lets try to avoid really screwing up the JSBsim model
    if ( get_Altitude() < -9000 ) {
	save_alt = get_Altitude();
	set_Altitude( 0.0 );
    }

    if(needTrim && (globals->get_options()->get_trim_mode() > 0)) {
	FGTrim *fgtrim;
	if(fgic->GetVcalibratedKtsIC() < 10 ) {
		fgic->SetVcalibratedKtsIC(0.0);
		fgtrim=new FGTrim(fdmex,fgic,tGround);
	} else {
		fgtrim=new FGTrim(fdmex,fgic,tLongitudinal);
	}	
	if(!fgtrim->DoTrim()) {
	    fgtrim->Report();
	    fgtrim->TrimStats();
	}  
	fgtrim->ReportState();
	delete fgtrim;
    
	needTrim=false;
    
         
	controls.set_elevator_trim(fdmex->GetFCS()->GetPitchTrimCmd());
	controls.set_elevator(fdmex->GetFCS()->GetDeCmd());
	controls.set_throttle(FGControls::ALL_ENGINES,
			      fdmex->GetFCS()->GetThrottleCmd(0)/100.0);
	controls.set_aileron(fdmex->GetFCS()->GetDaCmd());
	controls.set_rudder(fdmex->GetFCS()->GetDrCmd());
    
	FG_LOG( FG_FLIGHT, FG_INFO, "  Trim complete" );
    }  
  
    for( i=0; i<get_num_engines(); i++ ) {
	get_engine(i)->set_RPM( controls.get_throttle(i)*2700 );
	get_engine(i)->set_Throttle( controls.get_throttle(i) );
    }
    copy_to_JSBsim();
  
    for ( int i = 0; i < multiloop; i++ ) {
	fdmex->Run();
    }

    // printf("%d FG_Altitude = %.2f\n", i, FG_Altitude * 0.3048);
    // printf("%d Altitude = %.2f\n", i, Altitude * 0.3048);

    // translate JSBsim back to FG structure so that the
    // autopilot (and the rest of the sim can use the updated values

    copy_from_JSBsim();
    
 

    // but lets restore our original bogus altitude when we are done

    if ( save_alt < -9000.0 ) {
	set_Altitude( save_alt );
    }
  
    //climb rate now set from FDM in copy_from_x()
    return true;
}

/******************************************************************************/

// Convert from the FGInterface struct to the JSBsim generic_ struct

bool FGJSBsim::copy_to_JSBsim() {
    // copy control positions into the JSBsim structure

    fdmex->GetFCS()->SetDaCmd( controls.get_aileron());
    fdmex->GetFCS()->SetDeCmd( controls.get_elevator());
    fdmex->GetFCS()->SetPitchTrimCmd(controls.get_elevator_trim());
    fdmex->GetFCS()->SetDrCmd( -1*controls.get_rudder());
    fdmex->GetFCS()->SetDfCmd( controls.get_flaps() );
    fdmex->GetFCS()->SetDsbCmd( 0.0 ); //speedbrakes
    fdmex->GetFCS()->SetDspCmd( 0.0 ); //spoilers
    fdmex->GetFCS()->SetThrottleCmd( FGControls::ALL_ENGINES,
				     controls.get_throttle( 0 ) * 100.0 );

    fdmex->GetFCS()->SetLBrake( controls.get_brake( 0 ) );
    fdmex->GetFCS()->SetRBrake( controls.get_brake( 1 ) );
    fdmex->GetFCS()->SetCBrake( controls.get_brake( 2 ) );

    fdmex->GetPosition()->SetRunwayRadius(scenery.cur_radius*METER_TO_FEET);
    fdmex->GetPosition()->SetSeaLevelRadius(get_Sea_level_radius());

    fdmex->GetAtmosphere()->SetExTemperature(get_Static_temperature());
    fdmex->GetAtmosphere()->SetExPressure(get_Static_pressure());
    fdmex->GetAtmosphere()->SetExDensity(get_Density());
    fdmex->GetAtmosphere()->SetWindNED(get_V_north_airmass(),
				       get_V_east_airmass(),
				       get_V_down_airmass());

    return true;
}

/******************************************************************************/

// Convert from the JSBsim generic_ struct to the FGInterface struct

bool FGJSBsim::copy_from_JSBsim() {
    unsigned i, j;
  
    _set_Inertias( fdmex->GetAircraft()->GetMass(),
		   fdmex->GetAircraft()->GetIxx(),
		   fdmex->GetAircraft()->GetIyy(),
		   fdmex->GetAircraft()->GetIzz(),
		   fdmex->GetAircraft()->GetIxz() );
  
    _set_CG_Position( fdmex->GetAircraft()->GetXYZcg()(1),
		      fdmex->GetAircraft()->GetXYZcg()(2),
		      fdmex->GetAircraft()->GetXYZcg()(3) );
  
    _set_Accels_Body( fdmex->GetTranslation()->GetUVWdot()(1),
		      fdmex->GetTranslation()->GetUVWdot()(2),
		      fdmex->GetTranslation()->GetUVWdot()(3) );
  
    _set_Accels_CG_Body( fdmex->GetTranslation()->GetUVWdot()(1),
			 fdmex->GetTranslation()->GetUVWdot()(2),
			 fdmex->GetTranslation()->GetUVWdot()(3) );
  
    //_set_Accels_CG_Body_N ( fdmex->GetTranslation()->GetNcg()(1),
    //                       fdmex->GetTranslation()->GetNcg()(2),
    //                       fdmex->GetTranslation()->GetNcg()(3) );
    //
    _set_Accels_Pilot_Body( fdmex->GetAuxiliary()->GetPilotAccel()(1),
			    fdmex->GetAuxiliary()->GetPilotAccel()(2),
			    fdmex->GetAuxiliary()->GetPilotAccel()(3) );
  
    //_set_Accels_Pilot_Body_N( fdmex->GetAuxiliary()->GetNpilot()(1),
    //                         fdmex->GetAuxiliary()->GetNpilot()(2),
    //                         fdmex->GetAuxiliary()->GetNpilot()(3) );
  
    _set_Nlf( fdmex->GetAircraft()->GetNlf() );
  
    // Velocities

    _set_Velocities_Local( fdmex->GetPosition()->GetVn(),
			   fdmex->GetPosition()->GetVe(),
			   fdmex->GetPosition()->GetVd() );

    _set_Velocities_Wind_Body( fdmex->GetTranslation()->GetUVW()(1),
			       fdmex->GetTranslation()->GetUVW()(2),
			       fdmex->GetTranslation()->GetUVW()(3) );
    
    _set_V_rel_wind( fdmex->GetTranslation()->GetVt() );
    
    _set_V_equiv_kts( fdmex->GetAuxiliary()->GetVequivalentKTS() );

    // _set_V_calibrated( fdmex->GetAuxiliary()->GetVcalibratedFPS() );

    _set_V_calibrated_kts( fdmex->GetAuxiliary()->GetVcalibratedKTS() );
  
    _set_V_ground_speed( fdmex->GetPosition()->GetVground() );

    _set_Omega_Body( fdmex->GetRotation()->GetPQR()(1),
		     fdmex->GetRotation()->GetPQR()(2),
		     fdmex->GetRotation()->GetPQR()(3) );

    _set_Euler_Rates( fdmex->GetRotation()->GetEulerRates()(1),
		      fdmex->GetRotation()->GetEulerRates()(2),
		      fdmex->GetRotation()->GetEulerRates()(3) );

    _set_Geocentric_Rates(fdmex->GetPosition()->GetLatitudeDot(),
			  fdmex->GetPosition()->GetLongitudeDot(),
			  fdmex->GetPosition()->Gethdot() );

    _set_Mach_number( fdmex->GetTranslation()->GetMach() );

    // Positions
    _updatePosition( fdmex->GetPosition()->GetLatitude(),
                     fdmex->GetPosition()->GetLongitude(),
		     fdmex->GetPosition()->Geth() );
    
    _set_Euler_Angles( fdmex->GetRotation()->Getphi(),
		       fdmex->GetRotation()->Gettht(),
		       fdmex->GetRotation()->Getpsi() );

    _set_Alpha( fdmex->GetTranslation()->Getalpha() );
    _set_Beta( fdmex->GetTranslation()->Getbeta() );

    
    _set_Gamma_vert_rad( fdmex->GetPosition()->GetGamma() );
    // set_Gamma_horiz_rad( Gamma_horiz_rad );

    _set_Earth_position_angle( fdmex->GetAuxiliary()->GetEarthPositionAngle() );

    _set_Climb_Rate( fdmex->GetPosition()->Gethdot() );
    

    for ( i = 1; i <= 3; i++ ) {
	for ( j = 1; j <= 3; j++ ) {
	    _set_T_Local_to_Body( i, j, fdmex->GetState()->GetTl2b()(i,j) );
	}
    }
    return true;
}

void FGJSBsim::snap_shot(void) {
  	fgic->SetLatitudeRadIC(get_Lat_geocentric() );
  	fgic->SetLongitudeRadIC( get_Longitude() );
  	fgic->SetAltitudeFtIC( get_Altitude() );
  	fgic->SetTerrainAltitudeFtIC( get_Runway_altitude() );
  	fgic->SetVtrueFpsIC( get_V_rel_wind() );
  	fgic->SetPitchAngleRadIC( get_Theta() );
  	fgic->SetRollAngleRadIC( get_Phi() );
  	fgic->SetTrueHeadingRadIC( get_Psi() );
  	fgic->SetClimbRateFpsIC( get_Climb_Rate() );
}				


//Positions
void FGJSBsim::set_Latitude(double lat) {
    double sea_level_radius_meters,lat_geoc;
    
    FG_LOG(FG_FLIGHT,FG_INFO,"FGJSBsim::set_Latitude: " << lat ); 
    
    snap_shot();
    sgGeodToGeoc( lat, get_Altitude() , &sea_level_radius_meters, &lat_geoc);
    fgic->SetSeaLevelRadiusFtIC( sea_level_radius_meters * METER_TO_FEET  );
    fgic->SetLatitudeRadIC( lat_geoc );
    fdmex->RunIC(fgic); //loop JSBSim once
    copy_from_JSBsim(); //update the bus
    needTrim=true;
}  

void FGJSBsim::set_Longitude(double lon) {
    
    FG_LOG(FG_FLIGHT,FG_INFO,"FGJSBsim::set_Longitude: " << lon );
    
    snap_shot();
    fgic->SetLongitudeRadIC(lon);
    fdmex->RunIC(fgic); //loop JSBSim once
    copy_from_JSBsim(); //update the bus
    needTrim=true;
}  

void FGJSBsim::set_Altitude(double alt) {
    double sea_level_radius_meters,lat_geoc;
    
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Altitude: " << alt );    
    
    snap_shot();
    sgGeodToGeoc( get_Latitude(), alt , &sea_level_radius_meters, &lat_geoc);
    fgic->SetSeaLevelRadiusFtIC( sea_level_radius_meters * METER_TO_FEET );
    fgic->SetLatitudeRadIC( lat_geoc );
    fgic->SetAltitudeFtIC(alt);
    fdmex->RunIC(fgic); //loop JSBSim once
    copy_from_JSBsim(); //update the bus
    needTrim=true;
}
  
void FGJSBsim::set_V_calibrated_kts(double vc) {
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_V_calibrated_kts: " <<  vc );
    
    snap_shot();
    fgic->SetVcalibratedKtsIC(vc);
    fdmex->RunIC(fgic); //loop JSBSim once
    copy_from_JSBsim(); //update the bus
    needTrim=true;
}  

void FGJSBsim::set_Mach_number(double mach) {
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Mach_number: " <<  mach );
    
    snap_shot();
    fgic->SetMachIC(mach);
    fdmex->RunIC(fgic); //loop JSBSim once
    copy_from_JSBsim(); //update the bus
    needTrim=true;
}  

void FGJSBsim::set_Velocities_Local( double north, double east, double down ){
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Velocities_Local: " 
	   << north << ", " <<  east << ", " << down ); 
    
    snap_shot();
    fgic->SetVnorthFpsIC(north);
    fgic->SetVeastFpsIC(east);
    fgic->SetVdownFpsIC(down);
    fdmex->RunIC(fgic); //loop JSBSim once
    copy_from_JSBsim(); //update the bus
    needTrim=true;
}  

void FGJSBsim::set_Velocities_Wind_Body( double u, double v, double w){
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Velocities_Wind_Body: " 
	   << u << ", " <<  v << ", " <<  w );
    
    snap_shot();
    fgic->SetUBodyFpsIC(u);
    fgic->SetVBodyFpsIC(v);
    fgic->SetWBodyFpsIC(w);
    fdmex->RunIC(fgic); //loop JSBSim once
    copy_from_JSBsim(); //update the bus
    needTrim=true;
} 

//Euler angles 
void FGJSBsim::set_Euler_Angles( double phi, double theta, double psi ) {
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Euler_Angles: " 
	   << phi << ", " << theta << ", " << psi );
    
    snap_shot();
    fgic->SetPitchAngleRadIC(theta);
    fgic->SetRollAngleRadIC(phi);
    fgic->SetTrueHeadingRadIC(psi);
    fdmex->RunIC(fgic); //loop JSBSim once
    copy_from_JSBsim(); //update the bus 
    needTrim=true;                                        
}  

//Flight Path
void FGJSBsim::set_Climb_Rate( double roc) {
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Climb_Rate: " << roc );
    
    snap_shot();
    fgic->SetClimbRateFpsIC(roc);
    fdmex->RunIC(fgic); //loop JSBSim once
    copy_from_JSBsim(); //update the bus 
    needTrim=true;                                        
}  

void FGJSBsim::set_Gamma_vert_rad( double gamma) {
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Gamma_vert_rad: " << gamma );
    
    snap_shot();
    fgic->SetFlightPathAngleRadIC(gamma);
    fdmex->RunIC(fgic); //loop JSBSim once
    copy_from_JSBsim(); //update the bus  
    needTrim=true;                                       
}  

//Earth
void FGJSBsim::set_Sea_level_radius(double slr) {
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Sea_level_radius: " << slr );
    
    snap_shot();
    fgic->SetSeaLevelRadiusFtIC(slr);
    fdmex->RunIC(fgic); //loop JSBSim once
    copy_from_JSBsim(); //update the bus 
    needTrim=true;  
}  

void FGJSBsim::set_Runway_altitude(double ralt) {
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Runway_altitude: " << ralt );
    
    snap_shot();
    _set_Runway_altitude( ralt );
    fdmex->RunIC(fgic); //loop JSBSim once
    copy_from_JSBsim(); //update the bus 
    needTrim=true;  
}  

void FGJSBsim::set_Static_pressure(double p) { 
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Static_pressure: " << p );
    
    snap_shot();
    fdmex->GetAtmosphere()->SetExPressure(p);
    if(fdmex->GetAtmosphere()->External() == true)
	needTrim=true;
}
  
void FGJSBsim::set_Static_temperature(double T) { 
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Static_temperature: " << T );
    
    snap_shot();
    fdmex->GetAtmosphere()->SetExTemperature(T);
    if(fdmex->GetAtmosphere()->External() == true)
	needTrim=true;
}
 

void FGJSBsim::set_Density(double rho) {
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Density: " << rho );
    
    snap_shot();
    fdmex->GetAtmosphere()->SetExDensity(rho);
    if(fdmex->GetAtmosphere()->External() == true)
	needTrim=true;
}
  

void FGJSBsim::set_Velocities_Local_Airmass (double wnorth, 
					     double weast, 
					     double wdown ) {
    FG_LOG(FG_FLIGHT,FG_INFO, "FGJSBsim::set_Velocities_Local_Airmass: " 
	   << wnorth << ", " << weast << ", " << wdown );
    
    snap_shot();
    fdmex->GetAtmosphere()->SetWindNED(wnorth, weast, wdown );
    if(fdmex->GetAtmosphere()->External() == true)
        needTrim=true;
}