1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
5 Date started: 09/12/2000
6 Purpose: This module models a rocket engine
8 ------------- Copyright (C) 2000 Jon S. Berndt (jsb@hal-pc.org) --------------
10 This program is free software; you can redistribute it and/or modify it under
11 the terms of the GNU General Public License as published by the Free Software
12 Foundation; either version 2 of the License, or (at your option) any later
15 This program is distributed in the hope that it will be useful, but WITHOUT
16 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
17 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
20 You should have received a copy of the GNU General Public License along with
21 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
22 Place - Suite 330, Boston, MA 02111-1307, USA.
24 Further information about the GNU General Public License can also be found on
25 the world wide web at http://www.gnu.org.
27 FUNCTIONAL DESCRIPTION
28 --------------------------------------------------------------------------------
30 This class descends from the FGEngine class and models a rocket engine based on
31 parameters given in the engine config file for this class
34 --------------------------------------------------------------------------------
35 09/12/2000 JSB Created
37 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
39 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
47 static const char *IdSrc = "$Id$";
48 static const char *IdHdr = ID_ROCKET;
50 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
52 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
54 FGRocket::FGRocket(FGFDMExec* exec, FGConfigFile* Eng_cfg) : FGEngine(exec)
58 Name = Eng_cfg->GetValue("NAME");
59 Eng_cfg->GetNextConfigLine();
61 while (Eng_cfg->GetValue() != string("/FG_ROCKET")) {
63 if (token == "SHR") *Eng_cfg >> SHR;
64 else if (token == "MAX_PC") *Eng_cfg >> maxPC;
65 else if (token == "PROP_EFF") *Eng_cfg >> propEff;
66 else if (token == "MAXTHROTTLE") *Eng_cfg >> MaxThrottle;
67 else if (token == "MINTHROTTLE") *Eng_cfg >> MinThrottle;
68 else if (token == "SLFUELFLOWMAX") *Eng_cfg >> SLFuelFlowMax;
69 else if (token == "SLOXIFLOWMAX") *Eng_cfg >> SLOxiFlowMax;
70 else if (token == "VARIANCE") *Eng_cfg >> Variance;
71 else cerr << "Unhandled token in Engine config file: " << token << endl;
81 kFactor = (2.0*SHR*SHR/(SHR-1.0))*pow(2.0/(SHR+1), (SHR+1)/(SHR-1));
84 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
86 FGRocket::~FGRocket(void)
91 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
93 double FGRocket::Calculate(void)
97 if (!Flameout && !Starved) ConsumeFuel();
99 Throttle = FCS->GetThrottlePos(EngineNumber);
101 if (Throttle < MinThrottle || Starved) {
102 PctPower = Thrust = 0.0; // desired thrust
106 PctPower = Throttle / MaxThrottle;
107 PC = maxPC*PctPower * (1.0 + Variance * ((double)rand()/(double)RAND_MAX - 0.5));
108 Cf = sqrt(kFactor*(1 - pow(Thruster->GetPowerRequired()/(PC), (SHR-1)/SHR)));
112 return Thruster->Calculate(Cf*maxPC*PctPower*propEff);
115 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
117 string FGRocket::GetEngineLabels(void)
119 std::ostringstream buf;
121 buf << Name << "_ChamberPress[" << EngineNumber << "], "
122 << Thruster->GetThrusterLabels(EngineNumber);
127 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
129 string FGRocket::GetEngineValues(void)
131 std::ostringstream buf;
133 buf << PC << ", " << Thruster->GetThrusterValues(EngineNumber);
138 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
139 // The bitmasked value choices are as follows:
140 // unset: In this case (the default) JSBSim would only print
141 // out the normally expected messages, essentially echoing
142 // the config files as they are read. If the environment
143 // variable is not set, debug_lvl is set to 1 internally
144 // 0: This requests JSBSim not to output any messages
146 // 1: This value explicity requests the normal JSBSim
148 // 2: This value asks for a message to be printed out when
149 // a class is instantiated
150 // 4: When this value is set, a message is displayed when a
151 // FGModel object executes its Run() method
152 // 8: When this value is set, various runtime state variables
153 // are printed out periodically
154 // 16: When set various parameters are sanity checked and
155 // a message is printed out when they go out of bounds
157 void FGRocket::Debug(int from)
159 if (debug_lvl <= 0) return;
161 if (debug_lvl & 1) { // Standard console startup message output
162 if (from == 0) { // Constructor
163 cout << " Engine Name: " << Name << endl;
164 cout << " Specific Heat Ratio = " << SHR << endl;
165 cout << " Maximum Chamber Pressure = " << maxPC << endl;
166 cout << " Propulsive Efficiency = " << propEff << endl;
167 cout << " MaxThrottle = " << MaxThrottle << endl;
168 cout << " MinThrottle = " << MinThrottle << endl;
169 cout << " FuelFlowMax = " << SLFuelFlowMax << endl;
170 cout << " OxiFlowMax = " << SLOxiFlowMax << endl;
171 cout << " Variance = " << Variance << endl;
174 if (debug_lvl & 2 ) { // Instantiation/Destruction notification
175 if (from == 0) cout << "Instantiated: FGRocket" << endl;
176 if (from == 1) cout << "Destroyed: FGRocket" << endl;
178 if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
180 if (debug_lvl & 8 ) { // Runtime state variables
182 if (debug_lvl & 16) { // Sanity checking
184 if (debug_lvl & 64) {
185 if (from == 0) { // Constructor
186 cout << IdSrc << endl;
187 cout << IdHdr << endl;