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flightgear/Simulator/FDM/JSBsim/FGAircraft.cpp
curt 970ca13328 Updated contributed by Jon Berndt.
1999-06-29 15:30:30 +00:00

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/*******************************************************************************
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.
********************************************************************************
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 <sys/stat.h>
#include <sys/types.h>
#ifdef FGFS
# ifndef __BORLANDC__
# include <Include/compiler.h>
# endif
# ifdef FG_HAVE_STD_INCLUDES
# include <cmath>
# else
# include <math.h>
# endif
#else
# include <cmath>
#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;
axis = -1;
aircraftDef = aircraft_path + "/" + fname + "/" + fname + ".cfg";
ifstream aircraftfile(aircraftDef.c_str());
cout << "Reading Aircraft Configuration File: " << aircraftDef << endl;
numTanks = numEngines = 0;
numSelectedOxiTanks = numSelectedFuelTanks = 0;
while (!aircraftfile.fail()) {
holding_string.erase();
aircraftfile >> holding_string;
#ifdef __BORLANDC__
if (holding_string.compare(0, 2, "//") != 0) {
#else
if (holding_string.compare("//",0,2) != 0) {
#endif
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 >> Ixx;
cout << "Aircraft Ixx: " << Ixx << endl;
} else if (holding_string == "AC_IYY") {
aircraftfile >> Iyy;
cout << "Aircraft Iyy: " << Iyy << endl;
} else if (holding_string == "AC_IZZ") {
aircraftfile >> Izz;
cout << "Aircraft Izz: " << Izz << endl;
} else if (holding_string == "AC_IXZ") {
aircraftfile >> Ixz;
cout << "Aircraft Ixz: " << Ixz << endl;
} else if (holding_string == "AC_EMPTYWT") {
aircraftfile >> EmptyWeight;
EmptyMass = EmptyWeight / GRAVITY;
cout << "Aircraft Empty Weight: " << EmptyWeight << endl;
} else if (holding_string == "AC_CGLOC") {
aircraftfile >> Xcg >> Ycg >> Zcg;
cout << "Aircraft C.G.: " << Xcg << " " << Ycg << " " << Zcg << 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_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);
}
}
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();
FProp(); FAero(); FGear(); FMass();
MProp(); MAero(); MGear(); MMass();
PutState();
} else { // skip Run() execution this time
}
return false;
}
void FGAircraft::MassChange()
{
// 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; e<numEngines; e++) {
Fshortage = Oshortage = 0.0;
for (int t=0; t<numTanks; t++) {
switch(Engine[e]->GetType()) {
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 (int t=0; t<numTanks; t++)
Weight += Tank[t]->GetContents();
Mass = Weight / GRAVITY;
}
void FGAircraft::FAero(void)
{
float F[3];
F[0] = F[1] = F[2] = 0.0;
for (int axis_ctr = 0; axis_ctr < 3; axis_ctr++)
for (int ctr=0; ctr < coeff_ctr[axis_ctr]; ctr++)
F[axis_ctr] += Coeff[axis_ctr][ctr]->TotalValue();
Forces[0] += - F[DragCoeff]*cos(alpha)*cos(beta)
- F[SideCoeff]*cos(alpha)*sin(beta)
+ F[LiftCoeff]*sin(alpha);
Forces[1] += F[DragCoeff]*sin(beta)
+ F[SideCoeff]*cos(beta);
Forces[2] += - F[DragCoeff]*sin(alpha)*cos(beta)
- F[SideCoeff]*sin(alpha)*sin(beta)
- F[LiftCoeff]*cos(alpha);
}
void FGAircraft::FGear(void)
{
if (GearUp) {
} else {
}
}
void FGAircraft::FMass(void)
{
Forces[0] += -GRAVITY*sin(tht) * Mass;
Forces[1] += GRAVITY*sin(phi)*cos(tht) * Mass;
Forces[2] += GRAVITY*cos(phi)*cos(tht) * Mass;
}
void FGAircraft::FProp(void)
{
for (int i=0;i<numEngines;i++) {
Forces[0] += Engine[i]->CalcThrust();
}
}
void FGAircraft::MAero(void)
{
int axis_ctr, ctr;
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();
}
}
}
void FGAircraft::MGear(void)
{
if (GearUp) {
} else {
}
}
void FGAircraft::MMass(void)
{
}
void FGAircraft::MProp(void)
{
}
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)
{
}
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