1 /*******************************************************************************
6 Purpose: Encapsulates an aircraft
9 ------------- Copyright (C) 1999 Jon S. Berndt (jsb@hal-pc.org) -------------
11 This program is free software; you can redistribute it and/or modify it under
12 the terms of the GNU General Public License as published by the Free Software
13 Foundation; either version 2 of the License, or (at your option) any later
16 This program is distributed in the hope that it will be useful, but WITHOUT
17 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
18 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
21 You should have received a copy of the GNU General Public License along with
22 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
23 Place - Suite 330, Boston, MA 02111-1307, USA.
25 Further information about the GNU General Public License can also be found on
26 the world wide web at http://www.gnu.org.
28 FUNCTIONAL DESCRIPTION
29 --------------------------------------------------------------------------------
30 Models the aircraft reactions and forces. This class is instantiated by the
31 FGFDMExec class and scheduled as an FDM entry. LoadAircraft() is supplied with a
32 name of a valid, registered aircraft, and the data file is parsed.
35 --------------------------------------------------------------------------------
37 04/03/99 JSB Changed Aero() method to correct body axis force calculation
38 from wind vector. Fix provided by Tony Peden.
39 05/03/99 JSB Changed (for the better?) the way configurations are read in.
40 9/17/99 TP Combined force and moment functions. Added aero reference
41 point to config file. Added calculations for moments due to
42 difference in cg and aero reference point
44 ********************************************************************************
45 COMMENTS, REFERENCES, and NOTES
46 ********************************************************************************
47 [1] Cooke, Zyda, Pratt, and McGhee, "NPSNET: Flight Simulation Dynamic Modeling
48 Using Quaternions", Presence, Vol. 1, No. 4, pp. 404-420 Naval Postgraduate
50 [2] D. M. Henderson, "Euler Angles, Quaternions, and Transformation Matrices",
52 [3] Richard E. McFarland, "A Standard Kinematic Model for Flight Simulation at
53 NASA-Ames", NASA CR-2497, January 1975
54 [4] Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics",
55 Wiley & Sons, 1979 ISBN 0-471-03032-5
56 [5] Bernard Etkin, "Dynamics of Flight, Stability and Control", Wiley & Sons,
57 1982 ISBN 0-471-08936-2
59 The aerodynamic coefficients used in this model are:
62 CL0 - Reference lift at zero alpha
63 CD0 - Reference drag at zero alpha
64 CDM - Drag due to Mach
65 CLa - Lift curve slope (w.r.t. alpha)
66 CDa - Drag curve slope (w.r.t. alpha)
67 CLq - Lift due to pitch rate
68 CLM - Lift due to Mach
69 CLadt - Lift due to alpha rate
71 Cmadt - Pitching Moment due to alpha rate
72 Cm0 - Reference Pitching moment at zero alpha
73 Cma - Pitching moment slope (w.r.t. alpha)
74 Cmq - Pitch damping (pitch moment due to pitch rate)
75 CmM - Pitch Moment due to Mach
78 Cyb - Side force due to sideslip
79 Cyr - Side force due to yaw rate
81 Clb - Dihedral effect (roll moment due to sideslip)
82 Clp - Roll damping (roll moment due to roll rate)
83 Clr - Roll moment due to yaw rate
84 Cnb - Weathercocking stability (yaw moment due to sideslip)
85 Cnp - Rudder adverse yaw (yaw moment due to roll rate)
86 Cnr - Yaw damping (yaw moment due to yaw rate)
89 CLDe - Lift due to elevator
90 CDDe - Drag due to elevator
91 CyDr - Side force due to rudder
92 CyDa - Side force due to aileron
94 CmDe - Pitch moment due to elevator
95 ClDa - Roll moment due to aileron
96 ClDr - Roll moment due to rudder
97 CnDr - Yaw moment due to rudder
98 CnDa - Yaw moment due to aileron
100 ********************************************************************************
102 *******************************************************************************/
104 #include <sys/stat.h>
105 #include <sys/types.h>
108 # ifndef __BORLANDC__
109 # include <simgear/compiler.h>
111 # ifdef FG_HAVE_STD_INCLUDES
120 #include "FGAircraft.h"
121 #include "FGTranslation.h"
122 #include "FGRotation.h"
123 #include "FGAtmosphere.h"
125 #include "FGFDMExec.h"
127 #include "FGPosition.h"
128 #include "FGAuxiliary.h"
129 #include "FGOutput.h"
131 /*******************************************************************************
132 ************************************ CODE **************************************
133 *******************************************************************************/
135 FGAircraft::FGAircraft(FGFDMExec* fdmex) : FGModel(fdmex),
151 AxisIdx["PITCH"] = 4;
156 numTanks = numEngines = numSelectedFuelTanks = numSelectedOxiTanks = 0;
160 /******************************************************************************/
163 FGAircraft::~FGAircraft(void) {}
165 /******************************************************************************/
167 bool FGAircraft::LoadAircraft(string aircraft_path, string engine_path, string fname) {
170 string aircraftCfgFileName;
173 AircraftPath = aircraft_path;
174 EnginePath = engine_path;
176 aircraftCfgFileName = AircraftPath + "/" + fname + "/" + fname + ".cfg";
178 FGConfigFile AC_cfg(aircraftCfgFileName);
180 ReadPrologue(&AC_cfg);
182 while ((AC_cfg.GetNextConfigLine() != "EOF") &&
183 (token = AC_cfg.GetValue()) != "/FDM_CONFIG") {
184 if (token == "METRICS") {
185 cout << " Reading Metrics" << endl;
186 ReadMetrics(&AC_cfg);
187 } else if (token == "AERODYNAMICS") {
188 cout << " Reading Aerodynamics" << endl;
189 ReadAerodynamics(&AC_cfg);
190 } else if (token == "UNDERCARRIAGE") {
191 cout << " Reading Landing Gear" << endl;
192 ReadUndercarriage(&AC_cfg);
193 } else if (token == "PROPULSION") {
194 cout << " Reading Propulsion" << endl;
195 ReadPropulsion(&AC_cfg);
196 } else if (token == "FLIGHT_CONTROL") {
197 cout << " Reading Flight Control" << endl;
198 ReadFlightControls(&AC_cfg);
199 } else if (token == "OUTPUT") {
207 /******************************************************************************/
209 bool FGAircraft::Run(void) {
210 if (!FGModel::Run()) { // if false then execute this Run()
213 for (int i = 1; i <= 3; i++) vForces(i) = vMoments(i) = 0.0;
223 } else { // skip Run() execution this time
230 /******************************************************************************/
232 void FGAircraft::MassChange() {
233 static FGColumnVector vXYZtank(3);
235 float IXXt, IYYt, IZZt, IXZt;
237 unsigned int axis_ctr;
239 for (axis_ctr=1; axis_ctr<=3; axis_ctr++) vXYZtank(axis_ctr) = 0.0;
241 // UPDATE TANK CONTENTS
243 // For each engine, cycle through the tanks and draw an equal amount of
244 // fuel (or oxidizer) from each active tank. The needed amount of fuel is
245 // determined by the engine in the FGEngine class. If more fuel is needed
246 // than is available in the tank, then that amount is considered a shortage,
247 // and will be drawn from the next tank. If the engine cannot be fed what it
248 // needs, it will be considered to be starved, and will shut down.
250 float Oshortage, Fshortage;
252 for (int e=0; e<numEngines; e++) {
253 Fshortage = Oshortage = 0.0;
254 for (t=0; t<numTanks; t++) {
255 switch(Engine[e]->GetType()) {
256 case FGEngine::etRocket:
258 switch(Tank[t]->GetType()) {
260 if (Tank[t]->GetSelected()) {
261 Fshortage = Tank[t]->Reduce((Engine[e]->CalcFuelNeed()/
262 numSelectedFuelTanks)*(dt*rate) + Fshortage);
265 case FGTank::ttOXIDIZER:
266 if (Tank[t]->GetSelected()) {
267 Oshortage = Tank[t]->Reduce((Engine[e]->CalcOxidizerNeed()/
268 numSelectedOxiTanks)*(dt*rate) + Oshortage);
274 case FGEngine::etPiston:
275 case FGEngine::etTurboJet:
276 case FGEngine::etTurboProp:
278 if (Tank[t]->GetSelected()) {
279 Fshortage = Tank[t]->Reduce((Engine[e]->CalcFuelNeed()/
280 numSelectedFuelTanks)*(dt*rate) + Fshortage);
285 if ((Fshortage <= 0.0) || (Oshortage <= 0.0)) Engine[e]->SetStarved();
286 else Engine[e]->SetStarved(false);
289 Weight = EmptyWeight;
290 for (t=0; t<numTanks; t++)
291 Weight += Tank[t]->GetContents();
293 Mass = Weight / GRAVITY;
294 // Calculate new CG here.
297 for (t=0; t<numTanks; t++) {
298 vXYZtank(eX) += Tank[t]->GetX()*Tank[t]->GetContents();
299 vXYZtank(eY) += Tank[t]->GetY()*Tank[t]->GetContents();
300 vXYZtank(eZ) += Tank[t]->GetZ()*Tank[t]->GetContents();
302 Tw += Tank[t]->GetContents();
305 vXYZcg = (vXYZtank + EmptyWeight*vbaseXYZcg) / (Tw + EmptyWeight);
307 // Calculate new moments of inertia here
309 IXXt = IYYt = IZZt = IXZt = 0.0;
310 for (t=0; t<numTanks; t++) {
311 IXXt += ((Tank[t]->GetX()-vXYZcg(eX))/12.0)*((Tank[t]->GetX() - vXYZcg(eX))/12.0)*Tank[t]->GetContents()/GRAVITY;
312 IYYt += ((Tank[t]->GetY()-vXYZcg(eY))/12.0)*((Tank[t]->GetY() - vXYZcg(eY))/12.0)*Tank[t]->GetContents()/GRAVITY;
313 IZZt += ((Tank[t]->GetZ()-vXYZcg(eZ))/12.0)*((Tank[t]->GetZ() - vXYZcg(eZ))/12.0)*Tank[t]->GetContents()/GRAVITY;
314 IXZt += ((Tank[t]->GetX()-vXYZcg(eX))/12.0)*((Tank[t]->GetZ() - vXYZcg(eZ))/12.0)*Tank[t]->GetContents()/GRAVITY;
317 Ixx = baseIxx + IXXt;
318 Iyy = baseIyy + IYYt;
319 Izz = baseIzz + IZZt;
320 Ixz = baseIxz + IXZt;
324 /******************************************************************************/
326 void FGAircraft::FMAero(void) {
327 static FGColumnVector vDXYZcg(3);
328 unsigned int axis_ctr,ctr;
330 for (axis_ctr=1; axis_ctr<=3; axis_ctr++) vFs(axis_ctr) = 0.0;
332 for (axis_ctr = 0; axis_ctr < 3; axis_ctr++) {
333 for (ctr=0; ctr < Coeff[axis_ctr].size(); ctr++) {
334 vFs(axis_ctr+1) += Coeff[axis_ctr][ctr].TotalValue();
338 vForces += State->GetTs2b(alpha, beta)*vFs;
340 // The d*cg distances below, given in inches, are the distances FROM the c.g.
341 // TO the reference point. Since the c.g. and ref point are given in inches in
342 // the structural system (X positive rearwards) and the body coordinate system
343 // is given with X positive out the nose, the dxcg and dzcg values are
344 // *rotated* 180 degrees about the Y axis.
346 vDXYZcg(eX) = -(vXYZrp(eX) - vXYZcg(eX))/12.0; //cg and rp values are in inches
347 vDXYZcg(eY) = (vXYZrp(eY) - vXYZcg(eY))/12.0;
348 vDXYZcg(eZ) = -(vXYZrp(eZ) - vXYZcg(eZ))/12.0;
350 vMoments(eL) += vForces(eZ)*vDXYZcg(eY) - vForces(eY)*vDXYZcg(eZ); // rolling moment
351 vMoments(eM) += vForces(eX)*vDXYZcg(eZ) - vForces(eZ)*vDXYZcg(eX); // pitching moment
352 vMoments(eN) += vForces(eY)*vDXYZcg(eX) - vForces(eX)*vDXYZcg(eY); // yawing moment
354 for (axis_ctr = 0; axis_ctr < 3; axis_ctr++) {
355 for (ctr = 0; ctr < Coeff[axis_ctr+3].size(); ctr++) {
356 vMoments(axis_ctr+1) += Coeff[axis_ctr+3][ctr].TotalValue();
361 /******************************************************************************/
363 void FGAircraft::FMGear(void) {
368 for (unsigned int i=0;i<lGear.size();i++) {
369 vForces += lGear[i]->Force();
370 vMoments += lGear[i]->Moment();
375 /******************************************************************************/
377 void FGAircraft::FMMass(void) {
378 vForces(eX) += -GRAVITY*sin(vEuler(eTht)) * Mass;
379 vForces(eY) += GRAVITY*sin(vEuler(ePhi))*cos(vEuler(eTht)) * Mass;
380 vForces(eZ) += GRAVITY*cos(vEuler(ePhi))*cos(vEuler(eTht)) * Mass;
383 /******************************************************************************/
385 void FGAircraft::FMProp(void) {
386 for (int i=0;i<numEngines;i++) {
387 vForces(eX) += Engine[i]->CalcThrust();
391 /******************************************************************************/
393 void FGAircraft::GetState(void) {
396 alpha = Translation->Getalpha();
397 beta = Translation->Getbeta();
398 vEuler = Rotation->GetEuler();
401 /******************************************************************************/
403 void FGAircraft::ReadMetrics(FGConfigFile* AC_cfg) {
407 AC_cfg->GetNextConfigLine();
409 while ((token = AC_cfg->GetValue()) != "/METRICS") {
410 *AC_cfg >> parameter;
411 if (parameter == "AC_WINGAREA") *AC_cfg >> WingArea;
412 else if (parameter == "AC_WINGSPAN") *AC_cfg >> WingSpan;
413 else if (parameter == "AC_CHORD") *AC_cfg >> cbar;
414 else if (parameter == "AC_IXX") *AC_cfg >> baseIxx;
415 else if (parameter == "AC_IYY") *AC_cfg >> baseIyy;
416 else if (parameter == "AC_IZZ") *AC_cfg >> baseIzz;
417 else if (parameter == "AC_IXZ") *AC_cfg >> baseIxz;
418 else if (parameter == "AC_EMPTYWT") *AC_cfg >> EmptyWeight;
419 else if (parameter == "AC_CGLOC") *AC_cfg >> vbaseXYZcg(eX) >> vbaseXYZcg(eY) >> vbaseXYZcg(eZ);
420 else if (parameter == "AC_EYEPTLOC") *AC_cfg >> vXYZep(eX) >> vXYZep(eY) >> vXYZep(eZ);
421 else if (parameter == "AC_AERORP") *AC_cfg >> vXYZrp(eX) >> vXYZrp(eY) >> vXYZrp(eZ);
422 else if (parameter == "AC_ALPHALIMITS") *AC_cfg >> alphaclmin >> alphaclmax;
426 /******************************************************************************/
428 void FGAircraft::ReadPropulsion(FGConfigFile* AC_cfg) {
433 AC_cfg->GetNextConfigLine();
435 while ((token = AC_cfg->GetValue()) != "/PROPULSION") {
436 *AC_cfg >> parameter;
438 if (parameter == "AC_ENGINE") {
440 *AC_cfg >> engine_name;
441 Engine[numEngines] = new FGEngine(FDMExec, EnginePath, engine_name, numEngines);
444 } else if (parameter == "AC_TANK") {
446 Tank[numTanks] = new FGTank(AC_cfg);
447 switch(Tank[numTanks]->GetType()) {
449 numSelectedFuelTanks++;
451 case FGTank::ttOXIDIZER:
452 numSelectedOxiTanks++;
460 /******************************************************************************/
462 void FGAircraft::ReadFlightControls(FGConfigFile* AC_cfg) {
465 FCS->LoadFCS(AC_cfg);
468 /******************************************************************************/
470 void FGAircraft::ReadAerodynamics(FGConfigFile* AC_cfg) {
473 AC_cfg->GetNextConfigLine();
475 Coeff.push_back(*(new CoeffArray()));
476 Coeff.push_back(*(new CoeffArray()));
477 Coeff.push_back(*(new CoeffArray()));
478 Coeff.push_back(*(new CoeffArray()));
479 Coeff.push_back(*(new CoeffArray()));
480 Coeff.push_back(*(new CoeffArray()));
482 while ((token = AC_cfg->GetValue()) != "/AERODYNAMICS") {
483 if (token == "AXIS") {
484 axis = AC_cfg->GetValue("NAME");
485 AC_cfg->GetNextConfigLine();
486 while ((token = AC_cfg->GetValue()) != "/AXIS") {
487 Coeff[AxisIdx[axis]].push_back(*(new FGCoefficient(FDMExec, AC_cfg)));
488 DisplayCoeffFactors(Coeff[AxisIdx[axis]].back().Getmultipliers());
490 AC_cfg->GetNextConfigLine();
495 /******************************************************************************/
497 void FGAircraft::ReadUndercarriage(FGConfigFile* AC_cfg) {
500 AC_cfg->GetNextConfigLine();
502 while ((token = AC_cfg->GetValue()) != "/UNDERCARRIAGE") {
503 lGear.push_back(new FGLGear(AC_cfg, FDMExec));
507 /******************************************************************************/
509 void FGAircraft::ReadOutput(FGConfigFile* AC_cfg) {
510 string token, parameter;
514 token = AC_cfg->GetValue("NAME");
515 Output->SetFilename(token);
516 token = AC_cfg->GetValue("TYPE");
517 Output->SetType(token);
518 AC_cfg->GetNextConfigLine();
520 while ((token = AC_cfg->GetValue()) != "/OUTPUT") {
521 *AC_cfg >> parameter;
522 if (parameter == "RATE_IN_HZ") *AC_cfg >> OutRate;
523 if (parameter == "SIMULATION") {
524 *AC_cfg >> parameter;
525 if (parameter == "ON") subsystems += ssSimulation;
527 if (parameter == "AEROSURFACES") {
528 *AC_cfg >> parameter;
529 if (parameter == "ON") subsystems += ssAerosurfaces;
531 if (parameter == "RATES") {
532 *AC_cfg >> parameter;
533 if (parameter == "ON") subsystems += ssRates;
535 if (parameter == "VELOCITIES") {
536 *AC_cfg >> parameter;
537 if (parameter == "ON") subsystems += ssVelocities;
539 if (parameter == "FORCES") {
540 *AC_cfg >> parameter;
541 if (parameter == "ON") subsystems += ssForces;
543 if (parameter == "MOMENTS") {
544 *AC_cfg >> parameter;
545 if (parameter == "ON") subsystems += ssMoments;
547 if (parameter == "ATMOSPHERE") {
548 *AC_cfg >> parameter;
549 if (parameter == "ON") subsystems += ssAtmosphere;
551 if (parameter == "MASSPROPS") {
552 *AC_cfg >> parameter;
553 if (parameter == "ON") subsystems += ssMassProps;
555 if (parameter == "POSITION") {
556 *AC_cfg >> parameter;
557 if (parameter == "ON") subsystems += ssPosition;
559 if (parameter == "COEFFICIENTS") {
560 *AC_cfg >> parameter;
561 if (parameter == "ON") subsystems += ssCoefficients;
563 if (parameter == "GROUND_REACTIONS") {
564 *AC_cfg >> parameter;
565 if (parameter == "ON") subsystems += ssGroundReactions;
569 Output->SetSubsystems(subsystems);
571 OutRate = OutRate>120?120:(OutRate<0?0:OutRate);
572 Output->SetRate( (int)(0.5 + 1.0/(State->Getdt()*OutRate)) );
575 /******************************************************************************/
577 void FGAircraft::ReadPrologue(FGConfigFile* AC_cfg) {
578 string token = AC_cfg->GetValue();
580 AircraftName = AC_cfg->GetValue("NAME");
581 cout << "Reading Aircraft Configuration File: " << AircraftName << endl;
582 scratch=AC_cfg->GetValue("VERSION").c_str();
584 CFGVersion = AC_cfg->GetValue("VERSION");
585 cout << " Version: " << CFGVersion << endl;
586 if (CFGVersion != NEEDED_CFG_VERSION) {
587 cout << endl << "YOU HAVE AN INCOMPATIBLE CFG FILE FOR THIS AIRCRAFT."
588 " RESULTS WILL BE UNPREDICTABLE !!" << endl;
589 cout << "Current version needed is: " << NEEDED_CFG_VERSION << endl;
590 cout << " You have version: " << CFGVersion << endl << endl;
597 /******************************************************************************/
599 void FGAircraft::DisplayCoeffFactors(int multipliers) {
600 cout << " Non-Dimensionalized by: ";
602 if (multipliers & FG_QBAR) cout << "qbar ";
603 if (multipliers & FG_WINGAREA) cout << "S ";
604 if (multipliers & FG_WINGSPAN) cout << "b ";
605 if (multipliers & FG_CBAR) cout << "c ";
606 if (multipliers & FG_ALPHA) cout << "alpha ";
607 if (multipliers & FG_ALPHADOT) cout << "alphadot ";
608 if (multipliers & FG_BETA) cout << "beta ";
609 if (multipliers & FG_BETADOT) cout << "betadot ";
610 if (multipliers & FG_PITCHRATE) cout << "q ";
611 if (multipliers & FG_ROLLRATE) cout << "p ";
612 if (multipliers & FG_YAWRATE) cout << "r ";
614 if (multipliers & FG_ELEVATOR_CMD) cout << "De cmd ";
615 if (multipliers & FG_AILERON_CMD) cout << "Da cmd ";
616 if (multipliers & FG_RUDDER_CMD) cout << "Dr cmd ";
617 if (multipliers & FG_FLAPS_CMD) cout << "Df cmd ";
618 if (multipliers & FG_SPOILERS_CMD) cout << "Dsp cmd ";
619 if (multipliers & FG_SPDBRAKE_CMD) cout << "Dsb cmd ";
621 if (multipliers & FG_ELEVATOR_POS) cout << "De ";
622 if (multipliers & FG_AILERON_POS) cout << "Da ";
623 if (multipliers & FG_RUDDER_POS) cout << "Dr ";
624 if (multipliers & FG_FLAPS_POS) cout << "Df ";
625 if (multipliers & FG_SPOILERS_POS) cout << "Dsp ";
626 if (multipliers & FG_SPDBRAKE_POS) cout << "Dsb ";
628 if (multipliers & FG_MACH) cout << "Mach ";
629 if (multipliers & FG_ALTITUDE) cout << "h ";
630 if (multipliers & FG_BI2VEL) cout << "b /(2*Vt) ";
631 if (multipliers & FG_CI2VEL) cout << "c /(2*Vt) ";
636 /******************************************************************************/
638 string FGAircraft::GetCoefficientStrings(void) {
639 string CoeffStrings = "";
640 bool firstime = true;
642 for (unsigned int axis = 0; axis < 6; axis++) {
643 for (unsigned int sd = 0; sd < Coeff[axis].size(); sd++) {
647 CoeffStrings += ", ";
649 CoeffStrings += Coeff[axis][sd].Getname();
656 /******************************************************************************/
658 string FGAircraft::GetCoefficientValues(void) {
659 string SDValues = "";
661 bool firstime = true;
663 for (unsigned int axis = 0; axis < 6; axis++) {
664 for (unsigned int sd = 0; sd < Coeff[axis].size(); sd++) {
670 sprintf(buffer, "%9.6f", Coeff[axis][sd].GetSD());
671 SDValues += string(buffer);
679 /******************************************************************************/
681 string FGAircraft::GetGroundReactionStrings(void) {
682 string GroundReactionStrings = "";
683 bool firstime = true;
685 for (unsigned int i=0;i<lGear.size();i++) {
686 if (!firstime) GroundReactionStrings += ", ";
687 GroundReactionStrings += (lGear[i]->GetName() + "_WOW, ");
688 GroundReactionStrings += (lGear[i]->GetName() + "_compressLength, ");
689 GroundReactionStrings += (lGear[i]->GetName() + "_compressSpeed, ");
690 GroundReactionStrings += (lGear[i]->GetName() + "_Force");
695 return GroundReactionStrings;
698 /******************************************************************************/
700 string FGAircraft::GetGroundReactionValues(void) {
702 string GroundReactionValues = "";
704 bool firstime = true;
706 for (unsigned int i=0;i<lGear.size();i++) {
707 if (!firstime) GroundReactionValues += ", ";
708 GroundReactionValues += string( lGear[i]->GetWOW()?"1":"0" ) + ", ";
709 GroundReactionValues += (string(gcvt(lGear[i]->GetCompLen(), 5, buff)) + ", ");
710 GroundReactionValues += (string(gcvt(lGear[i]->GetCompVel(), 6, buff)) + ", ");
711 GroundReactionValues += (string(gcvt(lGear[i]->GetCompForce(), 10, buff)));
716 return GroundReactionValues;