-/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-\r
- Module: FGPiston.cpp\r
- Author: Jon S. Berndt\r
- Date started: 09/12/2000\r
- Purpose: This module models a Piston engine\r
-\r
- ------------- Copyright (C) 2000 Jon S. Berndt (jsb@hal-pc.org) --------------\r
-\r
- This program is free software; you can redistribute it and/or modify it under\r
- the terms of the GNU General Public License as published by the Free Software\r
- Foundation; either version 2 of the License, or (at your option) any later\r
- version.\r
-\r
- This program is distributed in the hope that it will be useful, but WITHOUT\r
- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS\r
- FOR A PARTICULAR PURPOSE. See the GNU General Public License for more\r
- details.\r
-\r
- You should have received a copy of the GNU General Public License along with\r
- this program; if not, write to the Free Software Foundation, Inc., 59 Temple\r
- Place - Suite 330, Boston, MA 02111-1307, USA.\r
-\r
- Further information about the GNU General Public License can also be found on\r
- the world wide web at http://www.gnu.org.\r
-\r
-FUNCTIONAL DESCRIPTION\r
---------------------------------------------------------------------------------\r
-\r
-This class descends from the FGEngine class and models a Piston engine based on\r
-parameters given in the engine config file for this class\r
-\r
-HISTORY\r
---------------------------------------------------------------------------------\r
-09/12/2000 JSB Created\r
-\r
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-INCLUDES\r
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/\r
-\r
-#include "FGDefs.h"\r
-#include "FGPiston.h"\r
-#include "FGPropulsion.h"\r
-\r
-static const char *IdSrc = "$Id$";\r
-static const char *IdHdr = ID_PISTON;\r
-\r
-/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-CLASS IMPLEMENTATION\r
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/\r
-\r
-FGPiston::FGPiston(FGFDMExec* exec, FGConfigFile* Eng_cfg)\r
- : FGEngine(exec),\r
- MinManifoldPressure_inHg(6.5),\r
- MaxManifoldPressure_inHg(28.5),\r
- Displacement(360),\r
- MaxHP(200),\r
- Cycles(2),\r
- IdleRPM(600),\r
- // Set constants\r
- CONVERT_CUBIC_INCHES_TO_METERS_CUBED(1.638706e-5),\r
- R_air(287.3),\r
- rho_fuel(800), // estimate\r
- calorific_value_fuel(47.3e6),\r
- Cp_air(1005),\r
- Cp_fuel(1700)\r
-{\r
- string token;\r
-\r
- Name = Eng_cfg->GetValue("NAME");\r
- Eng_cfg->GetNextConfigLine();\r
- while (Eng_cfg->GetValue() != "/FG_PISTON") {\r
- *Eng_cfg >> token;\r
- if (token == "MINMP") *Eng_cfg >> MinManifoldPressure_inHg;\r
- else if (token == "MAXMP") *Eng_cfg >> MaxManifoldPressure_inHg;\r
- else if (token == "DISPLACEMENT") *Eng_cfg >> Displacement;\r
- else if (token == "MAXHP") *Eng_cfg >> MaxHP;\r
- else if (token == "CYCLES") *Eng_cfg >> Cycles;\r
- else if (token == "IDLERPM") *Eng_cfg >> IdleRPM;\r
- else if (token == "MAXTHROTTLE") *Eng_cfg >> MaxThrottle;\r
- else if (token == "MINTHROTTLE") *Eng_cfg >> MinThrottle;\r
- else if (token == "SLFUELFLOWMAX") *Eng_cfg >> SLFuelFlowMax;\r
- else cerr << "Unhandled token in Engine config file: " << token << endl;\r
- }\r
-\r
- if (debug_lvl > 0) {\r
- cout << "\n Engine Name: " << Name << endl;\r
- cout << " MinManifoldPressure: " << MinManifoldPressure_inHg << endl;\r
- cout << " MaxManifoldPressure: " << MaxManifoldPressure_inHg << endl;\r
- cout << " Displacement: " << Displacement << endl;\r
- cout << " MaxHP: " << MaxHP << endl;\r
- cout << " Cycles: " << Cycles << endl;\r
- cout << " IdleRPM: " << IdleRPM << endl;\r
- cout << " MaxThrottle: " << MaxThrottle << endl;\r
- cout << " MinThrottle: " << MinThrottle << endl;\r
- cout << " SLFuelFlowMax: " << SLFuelFlowMax << endl;\r
- }\r
-\r
- Type = etPiston;\r
- EngineNumber = 0; // FIXME: this should be the actual number\r
- OilTemp_degK = 298; // FIXME: should be initialized in FGEngine\r
-\r
- dt = State->Getdt();\r
-\r
- // Initialisation\r
- volumetric_efficiency = 0.8; // Actually f(speed, load) but this will get us running\r
-\r
- // First column is thi, second is neta (combustion efficiency)\r
- Lookup_Combustion_Efficiency = new FGTable(12);\r
- *Lookup_Combustion_Efficiency << 0.00 << 0.980;\r
- *Lookup_Combustion_Efficiency << 0.90 << 0.980;\r
- *Lookup_Combustion_Efficiency << 1.00 << 0.970;\r
- *Lookup_Combustion_Efficiency << 1.05 << 0.950;\r
- *Lookup_Combustion_Efficiency << 1.10 << 0.900;\r
- *Lookup_Combustion_Efficiency << 1.15 << 0.850;\r
- *Lookup_Combustion_Efficiency << 1.20 << 0.790;\r
- *Lookup_Combustion_Efficiency << 1.30 << 0.700;\r
- *Lookup_Combustion_Efficiency << 1.40 << 0.630;\r
- *Lookup_Combustion_Efficiency << 1.50 << 0.570;\r
- *Lookup_Combustion_Efficiency << 1.60 << 0.525;\r
- *Lookup_Combustion_Efficiency << 2.00 << 0.345;\r
-\r
- cout << endl;\r
- cout << " Combustion Efficiency table:" << endl;\r
- Lookup_Combustion_Efficiency->Print();\r
- cout << endl;\r
-\r
- Power_Mixture_Correlation = new FGTable(13);\r
- *Power_Mixture_Correlation << (14.7/1.6) << 78.0;\r
- *Power_Mixture_Correlation << 10 << 86.0;\r
- *Power_Mixture_Correlation << 11 << 93.5;\r
- *Power_Mixture_Correlation << 12 << 98.0;\r
- *Power_Mixture_Correlation << 13 << 100.0;\r
- *Power_Mixture_Correlation << 14 << 99.0;\r
- *Power_Mixture_Correlation << 15 << 96.4;\r
- *Power_Mixture_Correlation << 16 << 92.5;\r
- *Power_Mixture_Correlation << 17 << 88.0;\r
- *Power_Mixture_Correlation << 18 << 83.0;\r
- *Power_Mixture_Correlation << 19 << 78.5;\r
- *Power_Mixture_Correlation << 20 << 74.0;\r
- *Power_Mixture_Correlation << (14.7/0.6) << 58;\r
-\r
- cout << endl;\r
- cout << " Power Mixture Correlation table:" << endl;\r
- Power_Mixture_Correlation->Print();\r
- cout << endl;\r
-\r
- if (debug_lvl & 2) cout << "Instantiated: FGPiston" << endl;\r
-}\r
-\r
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-\r
-FGPiston::~FGPiston()\r
-{\r
- if (debug_lvl & 2) cout << "Destroyed: FGPiston" << endl;\r
-}\r
-\r
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-\r
-float FGPiston::Calculate(float PowerRequired)\r
-{\r
- float h,EngineMaxPower;\r
-\r
- // FIXME: calculate from actual fuel flow\r
- ConsumeFuel();\r
-\r
- Throttle = FCS->GetThrottlePos(EngineNumber);\r
- Mixture = FCS->GetMixturePos(EngineNumber);\r
-\r
- //\r
- // Input values.\r
- //\r
-\r
- p_amb = Atmosphere->GetPressure() * 48; // convert from lbs/ft2 to Pa\r
- p_amb_sea_level = Atmosphere->GetPressureSL() * 48;\r
- T_amb = Atmosphere->GetTemperature() * (5.0 / 9.0); // convert from Rankine to Kelvin\r
-\r
- RPM = Propulsion->GetThruster(EngineNumber)->GetRPM();\r
- //if (RPM < IdleRPM) RPM = IdleRPM; // kludge\r
- \r
- IAS = Auxiliary->GetVcalibratedKTS();\r
-\r
- if (Mixture >= 0.5) {\r
- doEngineStartup();\r
- doManifoldPressure();\r
- doAirFlow();\r
- doFuelFlow();\r
- doEnginePower();\r
- doEGT();\r
- doCHT();\r
- doOilTemperature();\r
- doOilPressure();\r
- } else {\r
- HP = 0;\r
- }\r
-\r
- PowerAvailable = (HP * HPTOFTLBSSEC) - PowerRequired;\r
- return PowerAvailable;\r
-}\r
-\r
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-/**\r
- * Start or stop the engine.\r
- */\r
-\r
-void FGPiston::doEngineStartup(void)\r
-{\r
- // TODO: check magnetos, spark, starter, etc. and decide whether\r
- // engine is running\r
-\r
- // Check parameters that may alter the operating state of the engine. \r
- // (spark, fuel, starter motor etc)\r
- bool spark;\r
- bool fuel;\r
- static int crank_counter = 0;\r
-\r
- // Check for spark\r
- Magneto_Left = false;\r
- Magneto_Right = false;\r
- // Magneto positions:\r
- // 0 -> off\r
- // 1 -> left only\r
- // 2 -> right only\r
- // 3 -> both\r
- if (Magnetos != 0) {\r
- spark = true;\r
- } else {\r
- spark = false;\r
- } // neglects battery voltage, master on switch, etc for now.\r
- \r
- if ((Magnetos == 1) || (Magnetos > 2)) Magneto_Left = true;\r
- if (Magnetos > 1) Magneto_Right = true;\r
-\r
- // Assume we have fuel for now\r
- fuel = true;\r
-\r
- // Check if we are turning the starter motor\r
- if (Cranking != Starter) {\r
- // This check saves .../cranking from getting updated every loop - they\r
- // only update when changed.\r
- Cranking = Starter;\r
- crank_counter = 0;\r
- }\r
-\r
- //Check mode of engine operation\r
- // ACK - unfortunately this hack doesn't work in JSBSim since the RPM is reset\r
- // each iteration by the propeller :-(\r
- if (Cranking) {\r
- crank_counter++;\r
- if (RPM <= 480) {\r
- RPM += 100;\r
- if (RPM > 480)\r
- RPM = 480;\r
- } else {\r
- // consider making a horrible noise if the starter is engaged with\r
- // the engine running\r
- }\r
- // TODO - find a better guess at cranking speed\r
- }\r
- \r
- // if ((!Running) && (spark) && (fuel) && (crank_counter > 120)) {\r
-\r
- if ((!Running) && (spark) && (fuel)) {\r
- // start the engine if revs high enough\r
- if (RPM > 450) {\r
- // For now just instantaneously start but later we should maybe crank for\r
- // a bit\r
- Running = true;\r
- // RPM = 600;\r
- }\r
- }\r
-\r
- if ( (Running) && ((!spark)||(!fuel)) ) {\r
- // Cut the engine\r
- // note that we only cut the power - the engine may continue to\r
- // spin if the prop is in a moving airstream\r
- Running = false;\r
- }\r
-\r
- // And finally a last check for stalling\r
- if (Running) { \r
- //Check if we have stalled the engine\r
- if (RPM == 0) {\r
- Running = false;\r
- } else if ((RPM <= 480) && (Cranking)) {\r
- // Make sure the engine noise dosn't play if the engine won't\r
- // start due to eg mixture lever pulled out.\r
- Running = false;\r
- }\r
- }\r
-}\r
-\r
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-\r
-/**\r
- * Calculate the nominal manifold pressure in inches hg\r
- *\r
- * This function calculates nominal manifold pressure directly\r
- * from the throttle position, and does not adjust it for the\r
- * difference between the pressure at sea level and the pressure\r
- * at the current altitude (that adjustment takes place in\r
- * {@link #doEnginePower}).\r
- *\r
- * TODO: changes in MP should not be instantaneous -- introduce\r
- * a lag between throttle changes and MP changes, to allow pressure\r
- * to build up or disperse.\r
- *\r
- * Inputs: MinManifoldPressure_inHg, MaxManifoldPressure_inHg, Throttle\r
- *\r
- * Outputs: ManifoldPressure_inHg\r
- */\r
-\r
-void FGPiston::doManifoldPressure(void)\r
-{\r
- ManifoldPressure_inHg = MinManifoldPressure_inHg +\r
- (Throttle * (MaxManifoldPressure_inHg - MinManifoldPressure_inHg));\r
-}\r
-\r
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-/**\r
- * Calculate the air flow through the engine.\r
- *\r
- * Inputs: p_amb, R_air, T_amb, ManifoldPressure_inHg, Displacement,\r
- * RPM, volumetric_efficiency\r
- *\r
- * Outputs: rho_air, m_dot_air\r
- */\r
-\r
-void FGPiston::doAirFlow(void)\r
-{\r
- rho_air = p_amb / (R_air * T_amb);\r
- float rho_air_manifold = rho_air * ManifoldPressure_inHg / 29.6;\r
- float displacement_SI = Displacement * CONVERT_CUBIC_INCHES_TO_METERS_CUBED;\r
- float swept_volume = (displacement_SI * (RPM/60)) / 2;\r
- float v_dot_air = swept_volume * volumetric_efficiency;\r
- m_dot_air = v_dot_air * rho_air_manifold;\r
-}\r
-\r
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-/**\r
- * Calculate the fuel flow into the engine.\r
- *\r
- * Inputs: Mixture, thi_sea_level, p_amb_sea_level, p_amb, m_dot_air\r
- *\r
- * Outputs: equivalence_ratio, m_dot_fuel\r
- */\r
-\r
-void FGPiston::doFuelFlow(void)\r
-{\r
- float thi_sea_level = 1.3 * Mixture;\r
- equivalence_ratio = thi_sea_level * p_amb_sea_level / p_amb;\r
- m_dot_fuel = m_dot_air / 14.7 * equivalence_ratio;\r
-}\r
-\r
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-/**\r
- * Calculate the power produced by the engine.\r
- *\r
- * <p>Currently, the JSBSim propellor model does not allow the\r
- * engine to produce enough RPMs to get up to a high horsepower.\r
- * When tested with sufficient RPM, it has no trouble reaching\r
- * 200HP.</p>\r
- *\r
- * Inputs: ManifoldPressure_inHg, p_amb, p_amb_sea_level, RPM, T_amb, \r
- * equivalence_ratio, Cycles, MaxHP\r
- *\r
- * Outputs: Percentage_Power, HP\r
- */\r
-\r
-void FGPiston::doEnginePower(void)\r
-{\r
- float True_ManifoldPressure_inHg = ManifoldPressure_inHg * p_amb / p_amb_sea_level;\r
- float ManXRPM = True_ManifoldPressure_inHg * RPM;\r
- // FIXME: this needs to be generalized\r
- Percentage_Power = (6e-9 * ManXRPM * ManXRPM) + (8e-4 * ManXRPM) - 1.0;\r
- float T_amb_degF = (T_amb * 1.8) - 459.67;\r
- float T_amb_sea_lev_degF = (288 * 1.8) - 459.67; \r
- Percentage_Power =\r
- Percentage_Power + ((T_amb_sea_lev_degF - T_amb_degF) * 7 /120);\r
- float Percentage_of_best_power_mixture_power =\r
- Power_Mixture_Correlation->GetValue(14.7 / equivalence_ratio);\r
- Percentage_Power =\r
- Percentage_Power * Percentage_of_best_power_mixture_power / 100.0;\r
- if (Percentage_Power < 0.0)\r
- Percentage_Power = 0.0;\r
- else if (Percentage_Power > 100.0)\r
- Percentage_Power = 100.0;\r
- HP = Percentage_Power * MaxHP / 100.0;\r
-\r
- //Hack\r
- if (!Running) {\r
- if (Cranking) {\r
- if (RPM < 480) {\r
- HP = 3.0 + ((480 - RPM) / 10.0);\r
- } else {\r
- HP = 3.0;\r
- }\r
- } else {\r
- // Quick hack until we port the FMEP stuff\r
- if (RPM > 0.0)\r
- HP = -1.5;\r
- else\r
- HP = 0.0;\r
- }\r
- }\r
-}\r
-\r
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-/**\r
- * Calculate the exhaust gas temperature.\r
- *\r
- * Inputs: equivalence_ratio, m_dot_fuel, calorific_value_fuel, \r
- * Cp_air, m_dot_air, Cp_fuel, m_dot_fuel, T_amb, Percentage_Power\r
- *\r
- * Outputs: combustion_efficiency, ExhaustGasTemp_degK\r
- */\r
-\r
-void FGPiston::doEGT(void)\r
-{\r
- combustion_efficiency = Lookup_Combustion_Efficiency->GetValue(equivalence_ratio);\r
- float enthalpy_exhaust = m_dot_fuel * calorific_value_fuel * \r
- combustion_efficiency * 0.33;\r
- float heat_capacity_exhaust = (Cp_air * m_dot_air) + (Cp_fuel * m_dot_fuel);\r
- float delta_T_exhaust = enthalpy_exhaust / heat_capacity_exhaust;\r
- ExhaustGasTemp_degK = T_amb + delta_T_exhaust;\r
- ExhaustGasTemp_degK *= 0.444 + ((0.544 - 0.444) * Percentage_Power / 100.0);\r
-}\r
-\r
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-/**\r
- * Calculate the cylinder head temperature.\r
- *\r
- * Inputs: T_amb, IAS, rho_air, m_dot_fuel, calorific_value_fuel,\r
- * combustion_efficiency, RPM\r
- *\r
- * Outputs: CylinderHeadTemp_degK\r
- */\r
-\r
-void FGPiston::doCHT(void)\r
-{\r
- float h1 = -95.0;\r
- float h2 = -3.95;\r
- float h3 = -0.05;\r
-\r
- float arbitary_area = 1.0;\r
- float CpCylinderHead = 800.0;\r
- float MassCylinderHead = 8.0;\r
-\r
- float temperature_difference = CylinderHeadTemp_degK - T_amb;\r
- float v_apparent = IAS * 0.5144444;\r
- float v_dot_cooling_air = arbitary_area * v_apparent;\r
- float m_dot_cooling_air = v_dot_cooling_air * rho_air;\r
- float dqdt_from_combustion = \r
- m_dot_fuel * calorific_value_fuel * combustion_efficiency * 0.33;\r
- float dqdt_forced = (h2 * m_dot_cooling_air * temperature_difference) + \r
- (h3 * RPM * temperature_difference);\r
- float dqdt_free = h1 * temperature_difference;\r
- float dqdt_cylinder_head = dqdt_from_combustion + dqdt_forced + dqdt_free;\r
- \r
- float HeatCapacityCylinderHead = CpCylinderHead * MassCylinderHead;\r
- \r
- CylinderHeadTemp_degK = dqdt_cylinder_head / HeatCapacityCylinderHead;\r
-}\r
-\r
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-/**\r
- * Calculate the oil temperature.\r
- *\r
- * Inputs: Percentage_Power, running flag.\r
- *\r
- * Outputs: OilTemp_degK\r
- */\r
-\r
-void FGPiston::doOilTemperature(void)\r
-{\r
- float idle_percentage_power = 2.3; // approximately\r
- float target_oil_temp; // Steady state oil temp at the current engine conditions\r
- float time_constant; // The time constant for the differential equation\r
-\r
- if (Running) {\r
- target_oil_temp = 363;\r
- time_constant = 500; // Time constant for engine-on idling.\r
- if (Percentage_Power > idle_percentage_power) {\r
- time_constant /= ((Percentage_Power / idle_percentage_power) / 10.0); // adjust for power \r
- }\r
- } else {\r
- target_oil_temp = 298;\r
- time_constant = 1000; // Time constant for engine-off; reflects the fact\r
- // that oil is no longer getting circulated\r
- }\r
-\r
- float dOilTempdt = (target_oil_temp - OilTemp_degK) / time_constant;\r
-\r
- OilTemp_degK += (dOilTempdt * dt);\r
-}\r
-\r
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-/**\r
- * Calculate the oil pressure.\r
- *\r
- * Inputs: RPM\r
- *\r
- * Outputs: OilPressure_psi\r
- */\r
-\r
-void FGPiston::doOilPressure(void)\r
-{\r
- float Oil_Press_Relief_Valve = 60; // FIXME: may vary by engine\r
- float Oil_Press_RPM_Max = 1800; // FIXME: may vary by engine\r
- float Design_Oil_Temp = 85; // FIXME: may vary by engine\r
- // FIXME: WRONG!!! (85 degK???)\r
- float Oil_Viscosity_Index = 0.25;\r
-\r
- OilPressure_psi = (Oil_Press_Relief_Valve / Oil_Press_RPM_Max) * RPM;\r
-\r
- if (OilPressure_psi >= Oil_Press_Relief_Valve) {\r
- OilPressure_psi = Oil_Press_Relief_Valve;\r
- }\r
-\r
- OilPressure_psi += (Design_Oil_Temp - OilTemp_degK) * Oil_Viscosity_Index;\r
-}\r
-\r
-//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\r
-\r
-void FGPiston::Debug(void)\r
-{\r
- //TODO: Add your source code here\r
-}\r
-\r
+/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+ Module: FGPiston.cpp
+ Author: Jon S. Berndt, JSBSim framework
+ Dave Luff, Piston engine model
+ Date started: 09/12/2000
+ Purpose: This module models a Piston engine
+
+ ------------- Copyright (C) 2000 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
+--------------------------------------------------------------------------------
+
+This class descends from the FGEngine class and models a Piston engine based on
+parameters given in the engine config file for this class
+
+HISTORY
+--------------------------------------------------------------------------------
+09/12/2000 JSB Created
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+INCLUDES
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
+
+#include "FGPiston.h"
+#include "FGPropulsion.h"
+
+static const char *IdSrc = "$Id$";
+static const char *IdHdr = ID_PISTON;
+
+/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+CLASS IMPLEMENTATION
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
+
+FGPiston::FGPiston(FGFDMExec* exec, FGConfigFile* Eng_cfg) : FGEngine(exec),
+ CONVERT_CUBIC_INCHES_TO_METERS_CUBED(1.638706e-5),
+ R_air(287.3),
+ rho_fuel(800), // estimate
+ calorific_value_fuel(47.3e6),
+ Cp_air(1005),
+ Cp_fuel(1700)
+{
+ string token;
+
+ MinManifoldPressure_inHg = 6.5;
+ MaxManifoldPressure_inHg = 28.5;
+ Displacement = 360;
+ MaxHP = 200;
+ Cycles = 2;
+ IdleRPM = 600;
+
+ Name = Eng_cfg->GetValue("NAME");
+ Eng_cfg->GetNextConfigLine();
+ while (Eng_cfg->GetValue() != string("/FG_PISTON")) {
+ *Eng_cfg >> token;
+ if (token == "MINMP") *Eng_cfg >> MinManifoldPressure_inHg;
+ else if (token == "MAXMP") *Eng_cfg >> MaxManifoldPressure_inHg;
+ else if (token == "DISPLACEMENT") *Eng_cfg >> Displacement;
+ else if (token == "MAXHP") *Eng_cfg >> MaxHP;
+ else if (token == "CYCLES") *Eng_cfg >> Cycles;
+ else if (token == "IDLERPM") *Eng_cfg >> IdleRPM;
+ else if (token == "MAXTHROTTLE") *Eng_cfg >> MaxThrottle;
+ else if (token == "MINTHROTTLE") *Eng_cfg >> MinThrottle;
+ else cerr << "Unhandled token in Engine config file: " << token << endl;
+ }
+
+ Type = etPiston;
+ crank_counter = 0;
+ EngineNumber = 0;
+ OilTemp_degK = 298;
+ ManifoldPressure_inHg = Atmosphere->GetPressure() * 0.014138; // psf to in Hg
+
+ dt = State->Getdt();
+
+ // Initialisation
+ volumetric_efficiency = 0.8; // Actually f(speed, load) but this will get us running
+
+ // First column is thi, second is neta (combustion efficiency)
+ Lookup_Combustion_Efficiency = new FGTable(12);
+ *Lookup_Combustion_Efficiency << 0.00 << 0.980;
+ *Lookup_Combustion_Efficiency << 0.90 << 0.980;
+ *Lookup_Combustion_Efficiency << 1.00 << 0.970;
+ *Lookup_Combustion_Efficiency << 1.05 << 0.950;
+ *Lookup_Combustion_Efficiency << 1.10 << 0.900;
+ *Lookup_Combustion_Efficiency << 1.15 << 0.850;
+ *Lookup_Combustion_Efficiency << 1.20 << 0.790;
+ *Lookup_Combustion_Efficiency << 1.30 << 0.700;
+ *Lookup_Combustion_Efficiency << 1.40 << 0.630;
+ *Lookup_Combustion_Efficiency << 1.50 << 0.570;
+ *Lookup_Combustion_Efficiency << 1.60 << 0.525;
+ *Lookup_Combustion_Efficiency << 2.00 << 0.345;
+
+ Power_Mixture_Correlation = new FGTable(13);
+ *Power_Mixture_Correlation << (14.7/1.6) << 78.0;
+ *Power_Mixture_Correlation << 10 << 86.0;
+ *Power_Mixture_Correlation << 11 << 93.5;
+ *Power_Mixture_Correlation << 12 << 98.0;
+ *Power_Mixture_Correlation << 13 << 100.0;
+ *Power_Mixture_Correlation << 14 << 99.0;
+ *Power_Mixture_Correlation << 15 << 96.4;
+ *Power_Mixture_Correlation << 16 << 92.5;
+ *Power_Mixture_Correlation << 17 << 88.0;
+ *Power_Mixture_Correlation << 18 << 83.0;
+ *Power_Mixture_Correlation << 19 << 78.5;
+ *Power_Mixture_Correlation << 20 << 74.0;
+ *Power_Mixture_Correlation << (14.7/0.6) << 58;
+
+ Debug(0); // Call Debug() routine from constructor if needed
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+FGPiston::~FGPiston()
+{
+ Debug(1); // Call Debug() routine from constructor if needed
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+double FGPiston::Calculate(double PowerRequired)
+{
+ ConsumeFuel();
+
+ Throttle = FCS->GetThrottlePos(EngineNumber);
+ Mixture = FCS->GetMixturePos(EngineNumber);
+
+ //
+ // Input values.
+ //
+
+ p_amb = Atmosphere->GetPressure() * 48; // convert from lbs/ft2 to Pa
+ p_amb_sea_level = Atmosphere->GetPressureSL() * 48;
+ T_amb = Atmosphere->GetTemperature() * (5.0 / 9.0); // convert from Rankine to Kelvin
+
+ RPM = Propulsion->GetThruster(EngineNumber)->GetRPM();
+ //if (RPM < IdleRPM) RPM = IdleRPM; // kludge
+
+ IAS = Auxiliary->GetVcalibratedKTS();
+
+ doEngineStartup();
+ doManifoldPressure();
+ doAirFlow();
+ doFuelFlow();
+
+ //Now that the fuel flow is done check if the mixture is too lean to run the engine
+ //Assume lean limit at 22 AFR for now - thats a thi of 0.668
+ //This might be a bit generous, but since there's currently no audiable warning of impending
+ //cutout in the form of misfiring and/or rough running its probably reasonable for now.
+ if (equivalence_ratio < 0.668)
+ Running = false;
+
+ doEnginePower();
+ doEGT();
+ doCHT();
+ doOilTemperature();
+ doOilPressure();
+
+ PowerAvailable = (HP * hptoftlbssec) - PowerRequired;
+ return PowerAvailable;
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+/**
+ * Start or stop the engine.
+ */
+
+void FGPiston::doEngineStartup(void)
+{
+ // Check parameters that may alter the operating state of the engine.
+ // (spark, fuel, starter motor etc)
+ bool spark;
+ bool fuel;
+
+ // Check for spark
+ Magneto_Left = false;
+ Magneto_Right = false;
+ // Magneto positions:
+ // 0 -> off
+ // 1 -> left only
+ // 2 -> right only
+ // 3 -> both
+ if (Magnetos != 0) {
+ spark = true;
+ } else {
+ spark = false;
+ } // neglects battery voltage, master on switch, etc for now.
+
+ if ((Magnetos == 1) || (Magnetos > 2)) Magneto_Left = true;
+ if (Magnetos > 1) Magneto_Right = true;
+
+ // Assume we have fuel for now
+ fuel = !Starved;
+
+ // Check if we are turning the starter motor
+ if (Cranking != Starter) {
+ // This check saves .../cranking from getting updated every loop - they
+ // only update when changed.
+ Cranking = Starter;
+ crank_counter = 0;
+ }
+
+ //Check mode of engine operation
+ if (Cranking) {
+ crank_counter++;
+ if (RPM <= 480) {
+ // Do nothing !! - cranking power output is now handled in the doPower section
+ } else {
+ // consider making a horrible noise if the starter is engaged with
+ // the engine running
+ }
+ }
+
+ // if ((!Running) && (spark) && (fuel) && (crank_counter > 120)) {
+
+ if ((!Running) && (spark) && (fuel)) {
+ // start the engine if revs high enough
+ if (Cranking) {
+ if ((RPM > 450) && (crank_counter > 175)) {
+ //Add a little delay to startup on the starter
+ Running = true;
+ }
+ } else {
+ if (RPM > 450) {
+ Running = true;
+ //This allows us to in-air start when windmilling
+ }
+ }
+ }
+
+ if ( (Running) && ((!spark)||(!fuel)) ) {
+ // Cut the engine
+ // note that we only cut the power - the engine may continue to
+ // spin if the prop is in a moving airstream
+ Running = false;
+ }
+
+ // And finally a last check for stalling
+ if (Running) {
+ //Check if we have stalled the engine
+ if (RPM == 0) {
+ Running = false;
+ } else if ((RPM <= 480) && (Cranking)) {
+ // Make sure the engine noise dosn't play if the engine won't
+ // start due to eg mixture lever pulled out.
+ Running = false;
+ }
+ }
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+/**
+ * Calculate the nominal manifold pressure in inches hg
+ *
+ * This function calculates nominal manifold pressure directly
+ * from the throttle position, and does not adjust it for the
+ * difference between the pressure at sea level and the pressure
+ * at the current altitude (that adjustment takes place in
+ * {@link #doEnginePower}).
+ *
+ * TODO: changes in MP should not be instantaneous -- introduce
+ * a lag between throttle changes and MP changes, to allow pressure
+ * to build up or disperse.
+ *
+ * Inputs: MinManifoldPressure_inHg, MaxManifoldPressure_inHg, Throttle
+ *
+ * Outputs: ManifoldPressure_inHg
+ */
+
+void FGPiston::doManifoldPressure(void)
+{
+ if (Running || Cranking) {
+ ManifoldPressure_inHg = MinManifoldPressure_inHg +
+ (Throttle * (MaxManifoldPressure_inHg - MinManifoldPressure_inHg));
+ } else {
+ ManifoldPressure_inHg = Atmosphere->GetPressure() * 0.014138; // psf to in Hg
+ }
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+/**
+ * Calculate the air flow through the engine.
+ *
+ * At this point, ManifoldPressure_inHg still represents the sea-level
+ * MP, not adjusted for altitude.
+ *
+ * Inputs: p_amb, R_air, T_amb, ManifoldPressure_inHg, Displacement,
+ * RPM, volumetric_efficiency
+ *
+ * Outputs: rho_air, m_dot_air
+ */
+
+void FGPiston::doAirFlow(void)
+{
+ rho_air = p_amb / (R_air * T_amb);
+ double rho_air_manifold = rho_air * ManifoldPressure_inHg / 29.6;
+ double displacement_SI = Displacement * CONVERT_CUBIC_INCHES_TO_METERS_CUBED;
+ double swept_volume = (displacement_SI * (RPM/60)) / 2;
+ double v_dot_air = swept_volume * volumetric_efficiency;
+ m_dot_air = v_dot_air * rho_air_manifold;
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+/**
+ * Calculate the fuel flow into the engine.
+ *
+ * Inputs: Mixture, thi_sea_level, p_amb_sea_level, p_amb, m_dot_air
+ *
+ * Outputs: equivalence_ratio, m_dot_fuel
+ */
+
+void FGPiston::doFuelFlow(void)
+{
+ double thi_sea_level = 1.3 * Mixture;
+ equivalence_ratio = thi_sea_level * p_amb_sea_level / p_amb;
+ m_dot_fuel = m_dot_air / 14.7 * equivalence_ratio;
+ FuelFlow_gph = m_dot_fuel
+ * 3600 // seconds to hours
+ * 2.2046 // kg to lb
+ / 6.6; // lb to gal_us of kerosene
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+/**
+ * Calculate the power produced by the engine.
+ *
+ * Currently, the JSBSim propellor model does not allow the
+ * engine to produce enough RPMs to get up to a high horsepower.
+ * When tested with sufficient RPM, it has no trouble reaching
+ * 200HP.
+ *
+ * Inputs: ManifoldPressure_inHg, p_amb, p_amb_sea_level, RPM, T_amb,
+ * equivalence_ratio, Cycles, MaxHP
+ *
+ * Outputs: Percentage_Power, HP
+ */
+
+void FGPiston::doEnginePower(void)
+{
+ ManifoldPressure_inHg *= p_amb / p_amb_sea_level;
+ if (Running) {
+ double ManXRPM = ManifoldPressure_inHg * RPM;
+ // FIXME: this needs to be generalized
+ Percentage_Power = (6e-9 * ManXRPM * ManXRPM) + (8e-4 * ManXRPM) - 1.0;
+ double T_amb_degF = (T_amb * 1.8) - 459.67;
+ double T_amb_sea_lev_degF = (288 * 1.8) - 459.67;
+ Percentage_Power =
+ Percentage_Power + ((T_amb_sea_lev_degF - T_amb_degF) * 7 /120);
+ double Percentage_of_best_power_mixture_power =
+ Power_Mixture_Correlation->GetValue(14.7 / equivalence_ratio);
+ Percentage_Power =
+ Percentage_Power * Percentage_of_best_power_mixture_power / 100.0;
+ if (Percentage_Power < 0.0)
+ Percentage_Power = 0.0;
+ else if (Percentage_Power > 100.0)
+ Percentage_Power = 100.0;
+ HP = Percentage_Power * MaxHP / 100.0;
+ } else {
+ // Power output when the engine is not running
+ if (Cranking) {
+ if (RPM < 10) {
+ HP = 3.0; // This is a hack to prevent overshooting the idle rpm in the first time step
+ // It may possibly need to be changed if the prop model is changed.
+ } else if (RPM < 480) {
+ HP = 3.0 + ((480 - RPM) / 10.0);
+ // This is a guess - would be nice to find a proper starter moter torque curve
+ } else {
+ HP = 3.0;
+ }
+ } else {
+ // Quick hack until we port the FMEP stuff
+ if (RPM > 0.0)
+ HP = -1.5;
+ else
+ HP = 0.0;
+ }
+ }
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+/**
+ * Calculate the exhaust gas temperature.
+ *
+ * Inputs: equivalence_ratio, m_dot_fuel, calorific_value_fuel,
+ * Cp_air, m_dot_air, Cp_fuel, m_dot_fuel, T_amb, Percentage_Power
+ *
+ * Outputs: combustion_efficiency, ExhaustGasTemp_degK
+ */
+
+void FGPiston::doEGT(void)
+{
+ double delta_T_exhaust;
+ double enthalpy_exhaust;
+ double heat_capacity_exhaust;
+ double dEGTdt;
+
+ if ((Running) && (m_dot_air > 0.0)) { // do the energy balance
+ combustion_efficiency = Lookup_Combustion_Efficiency->GetValue(equivalence_ratio);
+ enthalpy_exhaust = m_dot_fuel * calorific_value_fuel *
+ combustion_efficiency * 0.33;
+ heat_capacity_exhaust = (Cp_air * m_dot_air) + (Cp_fuel * m_dot_fuel);
+ delta_T_exhaust = enthalpy_exhaust / heat_capacity_exhaust;
+ ExhaustGasTemp_degK = T_amb + delta_T_exhaust;
+ ExhaustGasTemp_degK *= 0.444 + ((0.544 - 0.444) * Percentage_Power / 100.0);
+ } else { // Drop towards ambient - guess an appropriate time constant for now
+ dEGTdt = (298.0 - ExhaustGasTemp_degK) / 100.0;
+ delta_T_exhaust = dEGTdt * dt;
+ ExhaustGasTemp_degK += delta_T_exhaust;
+ }
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+/**
+ * Calculate the cylinder head temperature.
+ *
+ * Inputs: T_amb, IAS, rho_air, m_dot_fuel, calorific_value_fuel,
+ * combustion_efficiency, RPM
+ *
+ * Outputs: CylinderHeadTemp_degK
+ */
+
+void FGPiston::doCHT(void)
+{
+ double h1 = -95.0;
+ double h2 = -3.95;
+ double h3 = -0.05;
+
+ double arbitary_area = 1.0;
+ double CpCylinderHead = 800.0;
+ double MassCylinderHead = 8.0;
+
+ double temperature_difference = CylinderHeadTemp_degK - T_amb;
+ double v_apparent = IAS * 0.5144444;
+ double v_dot_cooling_air = arbitary_area * v_apparent;
+ double m_dot_cooling_air = v_dot_cooling_air * rho_air;
+ double dqdt_from_combustion =
+ m_dot_fuel * calorific_value_fuel * combustion_efficiency * 0.33;
+ double dqdt_forced = (h2 * m_dot_cooling_air * temperature_difference) +
+ (h3 * RPM * temperature_difference);
+ double dqdt_free = h1 * temperature_difference;
+ double dqdt_cylinder_head = dqdt_from_combustion + dqdt_forced + dqdt_free;
+
+ double HeatCapacityCylinderHead = CpCylinderHead * MassCylinderHead;
+
+ CylinderHeadTemp_degK = dqdt_cylinder_head / HeatCapacityCylinderHead;
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+/**
+ * Calculate the oil temperature.
+ *
+ * Inputs: Percentage_Power, running flag.
+ *
+ * Outputs: OilTemp_degK
+ */
+
+void FGPiston::doOilTemperature(void)
+{
+ double idle_percentage_power = 2.3; // approximately
+ double target_oil_temp; // Steady state oil temp at the current engine conditions
+ double time_constant; // The time constant for the differential equation
+
+ if (Running) {
+ target_oil_temp = 363;
+ time_constant = 500; // Time constant for engine-on idling.
+ if (Percentage_Power > idle_percentage_power) {
+ time_constant /= ((Percentage_Power / idle_percentage_power) / 10.0); // adjust for power
+ }
+ } else {
+ target_oil_temp = 298;
+ time_constant = 1000; // Time constant for engine-off; reflects the fact
+ // that oil is no longer getting circulated
+ }
+
+ double dOilTempdt = (target_oil_temp - OilTemp_degK) / time_constant;
+
+ OilTemp_degK += (dOilTempdt * dt);
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+/**
+ * Calculate the oil pressure.
+ *
+ * Inputs: RPM
+ *
+ * Outputs: OilPressure_psi
+ */
+
+void FGPiston::doOilPressure(void)
+{
+ double Oil_Press_Relief_Valve = 60; // FIXME: may vary by engine
+ double Oil_Press_RPM_Max = 1800; // FIXME: may vary by engine
+ double Design_Oil_Temp = 85; // FIXME: may vary by engine
+ // FIXME: WRONG!!! (85 degK???)
+ double Oil_Viscosity_Index = 0.25;
+
+ OilPressure_psi = (Oil_Press_Relief_Valve / Oil_Press_RPM_Max) * RPM;
+
+ if (OilPressure_psi >= Oil_Press_Relief_Valve) {
+ OilPressure_psi = Oil_Press_Relief_Valve;
+ }
+
+ OilPressure_psi += (Design_Oil_Temp - OilTemp_degK) * Oil_Viscosity_Index;
+}
+
+//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+//
+// The bitmasked value choices are as follows:
+// unset: In this case (the default) JSBSim would only print
+// out the normally expected messages, essentially echoing
+// the config files as they are read. If the environment
+// variable is not set, debug_lvl is set to 1 internally
+// 0: This requests JSBSim not to output any messages
+// whatsoever.
+// 1: This value explicity requests the normal JSBSim
+// startup messages
+// 2: This value asks for a message to be printed out when
+// a class is instantiated
+// 4: When this value is set, a message is displayed when a
+// FGModel object executes its Run() method
+// 8: When this value is set, various runtime state variables
+// are printed out periodically
+// 16: When set various parameters are sanity checked and
+// a message is printed out when they go out of bounds
+
+void FGPiston::Debug(int from)
+{
+ if (debug_lvl <= 0) return;
+
+ if (debug_lvl & 1) { // Standard console startup message output
+ if (from == 0) { // Constructor
+
+ cout << "\n Engine Name: " << Name << endl;
+ cout << " MinManifoldPressure: " << MinManifoldPressure_inHg << endl;
+ cout << " MaxManifoldPressure: " << MaxManifoldPressure_inHg << endl;
+ cout << " Displacement: " << Displacement << endl;
+ cout << " MaxHP: " << MaxHP << endl;
+ cout << " Cycles: " << Cycles << endl;
+ cout << " IdleRPM: " << IdleRPM << endl;
+ cout << " MaxThrottle: " << MaxThrottle << endl;
+ cout << " MinThrottle: " << MinThrottle << endl;
+
+ cout << endl;
+ cout << " Combustion Efficiency table:" << endl;
+ Lookup_Combustion_Efficiency->Print();
+ cout << endl;
+
+ cout << endl;
+ cout << " Power Mixture Correlation table:" << endl;
+ Power_Mixture_Correlation->Print();
+ cout << endl;
+
+ }
+ }
+ if (debug_lvl & 2 ) { // Instantiation/Destruction notification
+ if (from == 0) cout << "Instantiated: FGPiston" << endl;
+ if (from == 1) cout << "Destroyed: FGPiston" << endl;
+ }
+ if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
+ }
+ if (debug_lvl & 8 ) { // Runtime state variables
+ }
+ if (debug_lvl & 16) { // Sanity checking
+ }
+ if (debug_lvl & 64) {
+ if (from == 0) { // Constructor
+ cout << IdSrc << endl;
+ cout << IdHdr << endl;
+ }
+ }
+}
+
+double
+FGPiston::CalcFuelNeed(void)
+{
+ return FuelFlow_gph / 3600 * State->Getdt() * Propulsion->GetRate();
+}
projects / flightgear.git / blobdiff