/******************************************************************************* 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" /******************************************************************************* ************************************ CODE ************************************** *******************************************************************************/ FGAircraft::FGAircraft(FGFDMExec* fdmex) : FGModel(fdmex) { int i; Name = "FGAircraft"; for (i=0;i<6;i++) coeff_ctr[i] = 0; } FGAircraft::~FGAircraft(void) { } bool FGAircraft::LoadAircraft(string aircraft_path, string engine_path, string fname) { string path; string fullpath; string filename; string aircraftDef; string tag; string holding_string; char scratch[128]; ifstream coeffInFile; streampos gpos; int axis; string axis_descript; bool readAeroRp=false; axis = -1; aircraftDef = aircraft_path + "/" + fname + "/" + fname + ".cfg"; ifstream aircraftfile(aircraftDef.c_str()); cout << "Reading Aircraft Configuration File: " << aircraftDef << endl; Output->SocketStatusOutput("Reading Aircraft Configuration File: " + aircraftDef); numTanks = numEngines = 0; numSelectedOxiTanks = numSelectedFuelTanks = 0; Xcg=Ycg=Zcg=0; //protection for no cg specified in file while (!aircraftfile.fail()) { holding_string.erase(); aircraftfile >> holding_string; #if defined(__BORLANDC__) || defined(FG_HAVE_NATIVE_SGI_COMPILERS) || defined(_MSC_VER) if (holding_string.compare(0, 2, "//") != 0) { #else if (holding_string.compare("//",0,2) != 0) { #endif if (holding_string == "CFG_VERSION") { aircraftfile >> CFGVersion; cout << "Config file version: " << CFGVersion << endl; if (CFGVersion < NEEDED_CFG_VERSION) { cout << endl << "YOU HAVE AN OLD CFG FILE FOR THIS AIRCRAFT." " RESULTS WILL BE UNPREDICTABLE !!" << endl << endl; } } else if (holding_string == "AIRCRAFT") { cout << "Reading in Aircraft parameters ..." << endl; } else if (holding_string == "AERODYNAMICS") { cout << "Reading in Aerodynamic parameters ..." << endl; } else if (holding_string == "AC_NAME") { aircraftfile >> AircraftName; // String with no embedded spaces cout << "Aircraft Name: " << AircraftName << endl; } else if (holding_string == "AC_WINGAREA") { aircraftfile >> WingArea; cout << "Aircraft Wing Area: " << WingArea << endl; } else if (holding_string == "AC_WINGSPAN") { aircraftfile >> WingSpan; cout << "Aircraft WingSpan: " << WingSpan << endl; } else if (holding_string == "AC_CHORD") { aircraftfile >> cbar; cout << "Aircraft Chord: " << cbar << endl; } else if (holding_string == "AC_IXX") { aircraftfile >> baseIxx; cout << "Aircraft Base Ixx: " << baseIxx << endl; } else if (holding_string == "AC_IYY") { aircraftfile >> baseIyy; cout << "Aircraft Base Iyy: " << baseIyy << endl; } else if (holding_string == "AC_IZZ") { aircraftfile >> baseIzz; cout << "Aircraft Base Izz: " << baseIzz << endl; } else if (holding_string == "AC_IXZ") { aircraftfile >> baseIxz; cout << "Aircraft Base Ixz: " << baseIxz << endl; } else if (holding_string == "AC_EMPTYWT") { aircraftfile >> EmptyWeight; EmptyMass = EmptyWeight / GRAVITY; cout << "Aircraft Empty Weight: " << EmptyWeight << endl; } else if (holding_string == "AC_AERORP") { aircraftfile >> Xrp >> Yrp >> Zrp; readAeroRp=true; cout << "Aerodynamic Reference Point: " << Xrp << " " << Yrp << " " << Zrp << endl; } else if (holding_string == "AC_CGLOC") { aircraftfile >> baseXcg >> baseYcg >> baseZcg; cout << "Aircraft Base C.G.: " << baseXcg << " " << baseYcg << " " << baseZcg << endl; } else if (holding_string == "AC_EYEPTLOC") { aircraftfile >> Xep >> Yep >> Zep; cout << "Pilot Eyepoint: " << Xep << " " << Yep << " " << Zep << endl; } else if (holding_string == "AC_TANK") { Tank[numTanks] = new FGTank(aircraftfile); switch(Tank[numTanks]->GetType()) { case FGTank::ttFUEL: numSelectedFuelTanks++; cout << "Reading in Fuel Tank #" << numSelectedFuelTanks << " parameters ..." << endl; break; case FGTank::ttOXIDIZER: numSelectedOxiTanks++; cout << "Reading in Oxidizer Tank #" << numSelectedOxiTanks << " parameters ..." << endl; break; } numTanks++; } else if (holding_string == "AC_GEAR") { lGear.push_back(new FGLGear(aircraftfile)); } else if (holding_string == "AC_ENGINE") { aircraftfile >> tag; cout << "Reading in " << tag << " Engine parameters ..." << endl; Engine[numEngines] = new FGEngine(FDMExec, engine_path, tag, numEngines); numEngines++; } else if (holding_string == "}") { } else if (holding_string == "{") { } else if (holding_string == "LIFT") { axis_descript = " Lift Coefficients ..."; axis = LiftCoeff; } else if (holding_string == "DRAG") { axis_descript = " Drag Coefficients ..."; axis = DragCoeff; } else if (holding_string == "SIDE") { axis_descript = " Side Coefficients ..."; axis = SideCoeff; } else if (holding_string == "ROLL") { axis_descript = " Roll Coefficients ..."; axis = RollCoeff; } else if (holding_string == "PITCH") { axis_descript = " Pitch Coefficients ..."; axis = PitchCoeff; } else if (holding_string == "YAW") { axis_descript = " Yaw Coefficients ..."; axis = YawCoeff; } if (axis >= 0) { cout << axis_descript << endl; aircraftfile >> tag; gpos = aircraftfile.tellg(); aircraftfile >> tag; if ( !(tag == "}") ) { while ( !(tag == "}") ) { aircraftfile.seekg(gpos); Coeff[axis][coeff_ctr[axis]] = new FGCoefficient(FDMExec, aircraftfile); coeff_ctr[axis]++; aircraftfile >> tag; gpos = aircraftfile.tellg(); aircraftfile >> tag; } } else { cout << " None found ..." << endl; } } axis = -1; } else { aircraftfile.getline(scratch, 127); } } if(!readAeroRp) { Xrp = Xcg; Yrp = Ycg; Zrp = Zcg; cout << "Aerodynamic reference point not found, set to empty weight cg location" << endl; } cout << "End of Configuration File Parsing." << endl; return true; } bool FGAircraft::Run(void) { if (!FGModel::Run()) { // if false then execute this Run() GetState(); for (int i = 0; i < 3; i++) Forces[i] = Moments[i] = 0.0; MassChange(); FMProp(); FMAero(); FMGear(); FMMass(); PutState(); } else { // skip Run() execution this time } return false; } void FGAircraft::MassChange() { float Xt, Xw, Yt, Yw, Zt, Zw, Tw; float IXXt, IYYt, IZZt, IXZt; int t; // 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 (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. Xt = Yt = Zt = Tw = 0; Xw = Yw = Zw = 0; for (t=0; tGetX()*Tank[t]->GetContents(); Yt += Tank[t]->GetY()*Tank[t]->GetContents(); Zt += Tank[t]->GetZ()*Tank[t]->GetContents(); Tw += Tank[t]->GetContents(); } Xcg = (Xt + EmptyWeight*baseXcg) / (Tw + EmptyWeight); Ycg = (Yt + EmptyWeight*baseYcg) / (Tw + EmptyWeight); Zcg = (Zt + EmptyWeight*baseZcg) / (Tw + EmptyWeight); // Calculate new moments of inertia here IXXt = IYYt = IZZt = IXZt = 0.0; for (t=0; tGetX()-Xcg)/12.0)*((Tank[t]->GetX() - Xcg)/12.0)*Tank[t]->GetContents()/GRAVITY; IYYt += ((Tank[t]->GetY()-Ycg)/12.0)*((Tank[t]->GetY() - Ycg)/12.0)*Tank[t]->GetContents()/GRAVITY; IZZt += ((Tank[t]->GetZ()-Zcg)/12.0)*((Tank[t]->GetZ() - Zcg)/12.0)*Tank[t]->GetContents()/GRAVITY; IXZt += ((Tank[t]->GetX()-Xcg)/12.0)*((Tank[t]->GetZ() - Zcg)/12.0)*Tank[t]->GetContents()/GRAVITY; } Ixx = baseIxx + IXXt; Iyy = baseIyy + IYYt; Izz = baseIzz + IZZt; Ixz = baseIxz + IXZt; } void FGAircraft::FMAero(void) { float F[3]; float dxcg,dycg,dzcg; float ca, cb, sa, sb; int axis_ctr,ctr; F[0] = F[1] = F[2] = 0.0; for (axis_ctr = 0; axis_ctr < 3; axis_ctr++) { for (ctr=0; ctr < coeff_ctr[axis_ctr]; ctr++) { F[axis_ctr] += Coeff[axis_ctr][ctr]->TotalValue(); Coeff[axis_ctr][ctr]->DumpSD(); } } ca = cos(alpha); sa = sin(alpha); cb = cos(beta); sb = sin(beta); Forces[0] += - F[DragCoeff]*ca*cb - F[SideCoeff]*ca*sb + F[LiftCoeff]*sa; Forces[1] += F[DragCoeff]*sb + F[SideCoeff]*cb; Forces[2] += - F[DragCoeff]*sa*cb - F[SideCoeff]*sa*sb - F[LiftCoeff]*ca; // The d*cg distances below, given in inches, are the distances FROM the c.g. // TO the reference point. Since the c.g. and ref point are given in inches in // the structural system (X positive rearwards) and the body coordinate system // is given with X positive out the nose, the dxcg and dzcg values are // *rotated* 180 degrees about the Y axis. dxcg = -(Xrp - Xcg)/12; //cg and rp values are in inches dycg = (Yrp - Ycg)/12; dzcg = -(Zrp - Zcg)/12; Moments[0] += Forces[2]*dycg - Forces[1]*dzcg; //rolling moment Moments[1] += Forces[0]*dzcg - Forces[2]*dxcg; //pitching moment Moments[2] += -Forces[0]*dycg + Forces[1]*dxcg; //yawing moment for (axis_ctr = 0; axis_ctr < 3; axis_ctr++) { for (ctr = 0; ctr < coeff_ctr[axis_ctr+3]; ctr++) { Moments[axis_ctr] += Coeff[axis_ctr+3][ctr]->TotalValue(); Coeff[axis_ctr+3][ctr]->DumpSD(); } } } void FGAircraft::FMGear(void) { if (GearUp) { // crash routine } else { for (int i=0;iCalcThrust(); } } void FGAircraft::GetState(void) { dt = State->Getdt(); alpha = Translation->Getalpha(); beta = Translation->Getbeta(); phi = Rotation->Getphi(); tht = Rotation->Gettht(); psi = Rotation->Getpsi(); } void FGAircraft::PutState(void) { }