/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Module: FGAircraft.cpp Author: Jon S. Berndt Date started: 12/12/98 Purpose: Encapsulates an aircraft Called by: FGFDMExec ------------- Copyright (C) 1999 Jon S. Berndt (jsb@hal-pc.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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. Further information about the GNU General Public License can also be found on the world wide web at http://www.gnu.org. FUNCTIONAL DESCRIPTION -------------------------------------------------------------------------------- Models the aircraft reactions and forces. This class is instantiated by the FGFDMExec class and scheduled as an FDM entry. LoadAircraft() is supplied with a name of a valid, registered aircraft, and the data file is parsed. HISTORY -------------------------------------------------------------------------------- 12/12/98 JSB Created 04/03/99 JSB Changed Aero() method to correct body axis force calculation from wind vector. Fix provided by Tony Peden. 05/03/99 JSB Changed (for the better?) the way configurations are read in. 9/17/99 TP Combined force and moment functions. Added aero reference point to config file. Added calculations for moments due to difference in cg and aero reference point %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% COMMENTS, REFERENCES, and NOTES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% [1] Cooke, Zyda, Pratt, and McGhee, "NPSNET: Flight Simulation Dynamic Modeling Using Quaternions", Presence, Vol. 1, No. 4, pp. 404-420 Naval Postgraduate School, January 1994 [2] D. M. Henderson, "Euler Angles, Quaternions, and Transformation Matrices", JSC 12960, July 1977 [3] Richard E. McFarland, "A Standard Kinematic Model for Flight Simulation at NASA-Ames", NASA CR-2497, January 1975 [4] Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics", Wiley & Sons, 1979 ISBN 0-471-03032-5 [5] Bernard Etkin, "Dynamics of Flight, Stability and Control", Wiley & Sons, 1982 ISBN 0-471-08936-2 The aerodynamic coefficients used in this model are: Longitudinal CL0 - Reference lift at zero alpha CD0 - Reference drag at zero alpha CDM - Drag due to Mach CLa - Lift curve slope (w.r.t. alpha) CDa - Drag curve slope (w.r.t. alpha) CLq - Lift due to pitch rate CLM - Lift due to Mach CLadt - Lift due to alpha rate Cmadt - Pitching Moment due to alpha rate Cm0 - Reference Pitching moment at zero alpha Cma - Pitching moment slope (w.r.t. alpha) Cmq - Pitch damping (pitch moment due to pitch rate) CmM - Pitch Moment due to Mach Lateral Cyb - Side force due to sideslip Cyr - Side force due to yaw rate Clb - Dihedral effect (roll moment due to sideslip) Clp - Roll damping (roll moment due to roll rate) Clr - Roll moment due to yaw rate Cnb - Weathercocking stability (yaw moment due to sideslip) Cnp - Rudder adverse yaw (yaw moment due to roll rate) Cnr - Yaw damping (yaw moment due to yaw rate) Control CLDe - Lift due to elevator CDDe - Drag due to elevator CyDr - Side force due to rudder CyDa - Side force due to aileron CmDe - Pitch moment due to elevator ClDa - Roll moment due to aileron ClDr - Roll moment due to rudder CnDr - Yaw moment due to rudder CnDa - Yaw moment due to aileron %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% INCLUDES %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/ #include #include #ifdef FGFS # ifndef __BORLANDC__ # include # endif # ifdef FG_HAVE_STD_INCLUDES # include # else # include # endif #else # include #endif #include "FGAircraft.h" #include "FGTranslation.h" #include "FGRotation.h" #include "FGAtmosphere.h" #include "FGState.h" #include "FGFDMExec.h" #include "FGFCS.h" #include "FGPosition.h" #include "FGAuxiliary.h" #include "FGOutput.h" /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% DEFINITIONS %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/ /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% GLOBAL DATA %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/ static const char *IdSrc = "$Id$"; static const char *IdHdr = ID_AIRCRAFT; extern char highint[5]; extern char halfint[5]; extern char normint[6]; extern char reset[5]; extern char underon[5]; extern char underoff[6]; extern char fgblue[6]; extern char fgcyan[6]; extern char fgred[6]; extern char fggreen[6]; extern char fgdef[6]; extern short debug_lvl; /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% CLASS IMPLEMENTATION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/ FGAircraft::FGAircraft(FGFDMExec* fdmex) : FGModel(fdmex), vMoments(3), vForces(3), vFs(3), vXYZrp(3), vbaseXYZcg(3), vXYZcg(3), vXYZep(3), vEuler(3) { Name = "FGAircraft"; AxisIdx["DRAG"] = 0; AxisIdx["SIDE"] = 1; AxisIdx["LIFT"] = 2; AxisIdx["ROLL"] = 3; AxisIdx["PITCH"] = 4; AxisIdx["YAW"] = 5; Coeff = new CoeffArray[6]; GearUp = false; alphaclmin = alphaclmax = 0; if (debug_lvl & 2) cout << "Instantiated: " << Name << endl; } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% FGAircraft::~FGAircraft() { unsigned int i,j; for (i=0; i<6; i++) { for (j=0; jGetGamma()) < 1.57) { nlf = vFs(eZ)/(Weight*cos(Position->GetGamma())); } } else { // skip Run() execution this time } return false; } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::MassChange() { static FGColumnVector vXYZtank(3); float Tw; float IXXt, IYYt, IZZt, IXZt; // unsigned int t; // unsigned int axis_ctr; /* for (axis_ctr=1; axis_ctr<=3; axis_ctr++) vXYZtank(axis_ctr) = 0.0; // UPDATE TANK CONTENTS // // For each engine, cycle through the tanks and draw an equal amount of // fuel (or oxidizer) from each active tank. The needed amount of fuel is // determined by the engine in the FGEngine class. If more fuel is needed // than is available in the tank, then that amount is considered a shortage, // and will be drawn from the next tank. If the engine cannot be fed what it // needs, it will be considered to be starved, and will shut down. float Oshortage, Fshortage; for (unsigned int e=0; eGetType()) { case FGEngine::etRocket: switch(Tank[t]->GetType()) { case FGTank::ttFUEL: if (Tank[t]->GetSelected()) { Fshortage = Tank[t]->Reduce((Engine[e]->CalcFuelNeed()/ numSelectedFuelTanks)*(dt*rate) + Fshortage); } break; case FGTank::ttOXIDIZER: if (Tank[t]->GetSelected()) { Oshortage = Tank[t]->Reduce((Engine[e]->CalcOxidizerNeed()/ numSelectedOxiTanks)*(dt*rate) + Oshortage); } break; } break; case FGEngine::etPiston: case FGEngine::etTurboJet: case FGEngine::etTurboProp: if (Tank[t]->GetSelected()) { Fshortage = Tank[t]->Reduce((Engine[e]->CalcFuelNeed()/ numSelectedFuelTanks)*(dt*rate) + Fshortage); } break; } } if ((Fshortage <= 0.0) || (Oshortage <= 0.0)) Engine[e]->SetStarved(); else Engine[e]->SetStarved(false); } */ Weight = EmptyWeight; // for (t=0; tGetContents(); Mass = Weight / GRAVITY; // Calculate new CG here. Tw = 0; // for (t=0; tGetX()*Tank[t]->GetContents(); // vXYZtank(eY) += Tank[t]->GetY()*Tank[t]->GetContents(); // vXYZtank(eZ) += Tank[t]->GetZ()*Tank[t]->GetContents(); // // Tw += Tank[t]->GetContents(); // } vXYZcg = (vXYZtank + EmptyWeight*vbaseXYZcg) / (Tw + EmptyWeight); // Calculate new moments of inertia here IXXt = IYYt = IZZt = IXZt = 0.0; // for (t=0; tGetX()-vXYZcg(eX))/12.0)*((Tank[t]->GetX() - vXYZcg(eX))/12.0)*Tank[t]->GetContents()/GRAVITY; // IYYt += ((Tank[t]->GetY()-vXYZcg(eY))/12.0)*((Tank[t]->GetY() - vXYZcg(eY))/12.0)*Tank[t]->GetContents()/GRAVITY; // IZZt += ((Tank[t]->GetZ()-vXYZcg(eZ))/12.0)*((Tank[t]->GetZ() - vXYZcg(eZ))/12.0)*Tank[t]->GetContents()/GRAVITY; // IXZt += ((Tank[t]->GetX()-vXYZcg(eX))/12.0)*((Tank[t]->GetZ() - vXYZcg(eZ))/12.0)*Tank[t]->GetContents()/GRAVITY; // } Ixx = baseIxx + IXXt; Iyy = baseIyy + IYYt; Izz = baseIzz + IZZt; Ixz = baseIxz + IXZt; } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::FMAero(void) { static FGColumnVector vDXYZcg(3); static FGColumnVector vAeroBodyForces(3); unsigned int axis_ctr,ctr; for (axis_ctr=1; axis_ctr<=3; axis_ctr++) vFs(axis_ctr) = 0.0; for (axis_ctr = 0; axis_ctr < 3; axis_ctr++) { for (ctr=0; ctr < Coeff[axis_ctr].size(); ctr++) { vFs(axis_ctr+1) += Coeff[axis_ctr][ctr]->TotalValue(); } } vAeroBodyForces = State->GetTs2b(alpha, beta)*vFs; vForces += vAeroBodyForces; // see http://home.earthlink.net/~apeden/jsbsim_moments_due_to_forces.txt // for details on this vDXYZcg(eX) = -(vXYZrp(eX) - vXYZcg(eX))/12.0; //cg and rp values are in inches vDXYZcg(eY) = (vXYZrp(eY) - vXYZcg(eY))/12.0; vDXYZcg(eZ) = -(vXYZrp(eZ) - vXYZcg(eZ))/12.0; vMoments(eL) += vAeroBodyForces(eZ)*vDXYZcg(eY) - vAeroBodyForces(eY)*vDXYZcg(eZ); // rolling moment vMoments(eM) += vAeroBodyForces(eX)*vDXYZcg(eZ) - vAeroBodyForces(eZ)*vDXYZcg(eX); // pitching moment vMoments(eN) += vAeroBodyForces(eY)*vDXYZcg(eX) - vAeroBodyForces(eX)*vDXYZcg(eY); // yawing moment for (axis_ctr = 0; axis_ctr < 3; axis_ctr++) { for (ctr = 0; ctr < Coeff[axis_ctr+3].size(); ctr++) { vMoments(axis_ctr+1) += Coeff[axis_ctr+3][ctr]->TotalValue(); } } } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::FMGear(void) { if ( !GearUp ) { vector ::iterator iGear = lGear.begin(); while (iGear != lGear.end()) { vForces += iGear->Force(); vMoments += iGear->Moment(); iGear++; } } else { // Crash Routine } } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::FMMass(void) { vForces(eX) += -GRAVITY*sin(vEuler(eTht)) * Mass; vForces(eY) += GRAVITY*sin(vEuler(ePhi))*cos(vEuler(eTht)) * Mass; vForces(eZ) += GRAVITY*cos(vEuler(ePhi))*cos(vEuler(eTht)) * Mass; } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::FMProp(void) { vForces += Propulsion->GetForces(); vMoments += Propulsion->GetMoments(); } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::GetState(void) { dt = State->Getdt(); alpha = Translation->Getalpha(); beta = Translation->Getbeta(); vEuler = Rotation->GetEuler(); } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::ReadMetrics(FGConfigFile* AC_cfg) { string token = ""; string parameter; AC_cfg->GetNextConfigLine(); while ((token = AC_cfg->GetValue()) != string("/METRICS")) { *AC_cfg >> parameter; if (parameter == string("AC_WINGAREA")) { *AC_cfg >> WingArea; cout << " WingArea: " << WingArea << endl; } else if (parameter == "AC_WINGSPAN") { *AC_cfg >> WingSpan; cout << " WingSpan: " << WingSpan << endl; } else if (parameter == "AC_CHORD") { *AC_cfg >> cbar; cout << " Chord: " << cbar << endl; } else if (parameter == "AC_IXX") { *AC_cfg >> baseIxx; cout << " baseIxx: " << baseIxx << endl; } else if (parameter == "AC_IYY") { *AC_cfg >> baseIyy; cout << " baseIyy: " << baseIyy << endl; } else if (parameter == "AC_IZZ") { *AC_cfg >> baseIzz; cout << " baseIzz: " << baseIzz << endl; } else if (parameter == "AC_IXZ") { *AC_cfg >> baseIxz; cout << " baseIxz: " << baseIxz << endl; } else if (parameter == "AC_EMPTYWT") { *AC_cfg >> EmptyWeight; cout << " EmptyWeight: " << EmptyWeight << endl; } else if (parameter == "AC_CGLOC") { *AC_cfg >> vbaseXYZcg(eX) >> vbaseXYZcg(eY) >> vbaseXYZcg(eZ); cout << " CG (x, y, z): " << vbaseXYZcg << endl; } else if (parameter == "AC_EYEPTLOC") { *AC_cfg >> vXYZep(eX) >> vXYZep(eY) >> vXYZep(eZ); cout << " Eyepoint (x, y, z): " << vXYZep << endl; } else if (parameter == "AC_AERORP") { *AC_cfg >> vXYZrp(eX) >> vXYZrp(eY) >> vXYZrp(eZ); cout << " Ref Pt (x, y, z): " << vXYZrp << endl; } else if (parameter == "AC_ALPHALIMITS") { *AC_cfg >> alphaclmin >> alphaclmax; cout << " Maximum Alpha: " << alphaclmax << " Minimum Alpha: " << alphaclmin << endl; } } } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::ReadPropulsion(FGConfigFile* AC_cfg) { if (!Propulsion->LoadPropulsion(AC_cfg)) { cerr << "Propulsion not successfully loaded" << endl; } } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::ReadFlightControls(FGConfigFile* AC_cfg) { if (!FCS->LoadFCS(AC_cfg)) { cerr << "Flight Controls not successfully loaded" << endl; } } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::ReadAerodynamics(FGConfigFile* AC_cfg) { string token, axis; AC_cfg->GetNextConfigLine(); while ((token = AC_cfg->GetValue()) != string("/AERODYNAMICS")) { if (token == "AXIS") { CoeffArray ca; axis = AC_cfg->GetValue("NAME"); AC_cfg->GetNextConfigLine(); while ((token = AC_cfg->GetValue()) != string("/AXIS")) { ca.push_back(new FGCoefficient(FDMExec, AC_cfg)); DisplayCoeffFactors(ca.back()->Getmultipliers()); } Coeff[AxisIdx[axis]]=ca; AC_cfg->GetNextConfigLine(); } } } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::ReadUndercarriage(FGConfigFile* AC_cfg) { string token; AC_cfg->GetNextConfigLine(); while ((token = AC_cfg->GetValue()) != string("/UNDERCARRIAGE")) { lGear.push_back(FGLGear(AC_cfg, FDMExec)); } } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::ReadOutput(FGConfigFile* AC_cfg) { string token, parameter; int OutRate = 0; int subsystems = 0; token = AC_cfg->GetValue("NAME"); Output->SetFilename(token); token = AC_cfg->GetValue("TYPE"); Output->SetType(token); AC_cfg->GetNextConfigLine(); while ((token = AC_cfg->GetValue()) != string("/OUTPUT")) { *AC_cfg >> parameter; if (parameter == "RATE_IN_HZ") *AC_cfg >> OutRate; if (parameter == "SIMULATION") { *AC_cfg >> parameter; if (parameter == "ON") subsystems += ssSimulation; } if (parameter == "AEROSURFACES") { *AC_cfg >> parameter; if (parameter == "ON") subsystems += ssAerosurfaces; } if (parameter == "RATES") { *AC_cfg >> parameter; if (parameter == "ON") subsystems += ssRates; } if (parameter == "VELOCITIES") { *AC_cfg >> parameter; if (parameter == "ON") subsystems += ssVelocities; } if (parameter == "FORCES") { *AC_cfg >> parameter; if (parameter == "ON") subsystems += ssForces; } if (parameter == "MOMENTS") { *AC_cfg >> parameter; if (parameter == "ON") subsystems += ssMoments; } if (parameter == "ATMOSPHERE") { *AC_cfg >> parameter; if (parameter == "ON") subsystems += ssAtmosphere; } if (parameter == "MASSPROPS") { *AC_cfg >> parameter; if (parameter == "ON") subsystems += ssMassProps; } if (parameter == "POSITION") { *AC_cfg >> parameter; if (parameter == "ON") subsystems += ssPosition; } if (parameter == "COEFFICIENTS") { *AC_cfg >> parameter; if (parameter == "ON") subsystems += ssCoefficients; } if (parameter == "GROUND_REACTIONS") { *AC_cfg >> parameter; if (parameter == "ON") subsystems += ssGroundReactions; } if (parameter == "FCS") { *AC_cfg >> parameter; if (parameter == "ON") subsystems += ssFCS; } } Output->SetSubsystems(subsystems); OutRate = OutRate>120?120:(OutRate<0?0:OutRate); Output->SetRate( (int)(0.5 + 1.0/(State->Getdt()*OutRate)) ); } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::ReadPrologue(FGConfigFile* AC_cfg) { string token = AC_cfg->GetValue(); string scratch; AircraftName = AC_cfg->GetValue("NAME"); cout << underon << "Reading Aircraft Configuration File" << underoff << ": " << highint << AircraftName << normint << endl; scratch = AC_cfg->GetValue("VERSION").c_str(); CFGVersion = AC_cfg->GetValue("VERSION"); cout << " Version: " << highint << CFGVersion << normint << endl; if (CFGVersion != string(NEEDED_CFG_VERSION)) { cout << endl << fgred << "YOU HAVE AN INCOMPATIBLE CFG FILE FOR THIS AIRCRAFT." " RESULTS WILL BE UNPREDICTABLE !!" << endl; cout << "Current version needed is: " << NEEDED_CFG_VERSION << endl; cout << " You have version: " << CFGVersion << endl << fgdef << endl; //exit(-1); } } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% void FGAircraft::DisplayCoeffFactors(vector multipliers) { cout << " Non-Dimensionalized by: "; for (unsigned int i=0; iparamdef[multipliers[i]]; cout << endl; } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% string FGAircraft::GetCoefficientStrings(void) { string CoeffStrings = ""; bool firstime = true; for (unsigned int axis = 0; axis < 6; axis++) { for (unsigned int sd = 0; sd < Coeff[axis].size(); sd++) { if (firstime) { firstime = false; } else { CoeffStrings += ", "; } CoeffStrings += Coeff[axis][sd]->Getname(); } } return CoeffStrings; } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% string FGAircraft::GetCoefficientValues(void) { string SDValues = ""; char buffer[10]; bool firstime = true; for (unsigned int axis = 0; axis < 6; axis++) { for (unsigned int sd = 0; sd < Coeff[axis].size(); sd++) { if (firstime) { firstime = false; } else { SDValues += ", "; } sprintf(buffer, "%9.6f", Coeff[axis][sd]->GetSD()); SDValues += string(buffer); } } return SDValues; } //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% string FGAircraft::GetGroundReactionStrings(void) { string GroundReactionStrings = ""; bool firstime = true; for (unsigned int i=0;i