1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
5 Date started: 09/12/2000
7 ------------- Copyright (C) 2000 Jon S. Berndt (jon@jsbsim.org) --------------
9 This program is free software; you can redistribute it and/or modify it under
10 the terms of the GNU Lesser General Public License as published by the Free Software
11 Foundation; either version 2 of the License, or (at your option) any later
14 This program is distributed in the hope that it will be useful, but WITHOUT
15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
16 FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
19 You should have received a copy of the GNU Lesser General Public License along with
20 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
21 Place - Suite 330, Boston, MA 02111-1307, USA.
23 Further information about the GNU Lesser General Public License can also be found on
24 the world wide web at http://www.gnu.org.
27 --------------------------------------------------------------------------------
28 09/12/2000 JSB Created
29 10/01/2001 DPM Modified to use equations from Dave Luff's piston model.
30 11/01/2008 RKJ Modified piston engine model for more general use.
31 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
33 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
38 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
40 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
43 #include "math/FGTable.h"
45 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
47 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
49 #define ID_PISTON "$Id: FGPiston.h,v 1.32 2011/10/11 16:16:16 jentron Exp $";
50 #define FG_MAX_BOOST_SPEEDS 3
52 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
54 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
58 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
60 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
62 /** Models a Supercharged Piston engine. Based on Dave Luff's model.
64 <h3>Configuration File Format:</h3>
67 <piston_engine name="{string}">
68 <minmp unit="{INHG | PA | ATM}"> {number} </minmp>
69 <maxmp unit="{INHG | PA | ATM}"> {number} </maxmp>
70 <idlerpm> {number} </idlerpm>
71 <maxrpm> {number} </maxrpm>
72 <maxhp unit="{HP | WATTS}"> {number} </maxhp>
73 <displacement unit="{IN3 | LTR | CC}"> {number} </displacement>
74 <cycles> {number} </cycles>
75 <bore unit="{IN | M}"> {number} </bore>
76 <stroke unit="{IN | M}"> {number} </stroke>
77 <cylinders> {number} </cylinders>
78 <compression-ratio> {number} </compression-ratio>
79 <sparkfaildrop> {number} </sparkfaildrop>
80 <static-friction unit="{HP | WATTS}"> {number} </static-friction>
81 <air-intake-impedance-factor> {number} </air-intake-impedance-factor>
82 <ram-air-factor> {number} </ram-air-factor>
83 <cooling-factor> {number} </cooling-factor>
84 <cylinder-head-mass unit="{KG | LBS}"> {number} </cylinder-head-mass>
85 <bsfc unit="{LBS/HP*HR | "KG/KW*HR"}"> {number} </bsfc>
86 <volumetric-efficiency> {number} </volumetric-efficiency>
87 <dynamic-fmep unit="{INHG | PA | ATM}"> {number} </dynamic-fmep>
88 <static-fmep unit="{INHG | PA | ATM}"> {number} </static-fmep>
89 <numboostspeeds> {number} </numboostspeeds>
90 <boostoverride> {0 | 1} </boostoverride>
91 <boostmanual> {0 | 1} </boostmanual>
92 <ratedboost1 unit="{INHG | PA | ATM}"> {number} </ratedboost1>
93 <ratedpower1 unit="{HP | WATTS}"> {number} </ratedpower1>
94 <ratedrpm1> {number} </ratedrpm1>
95 <ratedaltitude1 unit="{FT | M}"> {number} </ratedaltitude1>
96 <ratedboost2 unit="{INHG | PA | ATM}"> {number} </ratedboost2>
97 <ratedpower2 unit="{HP | WATTS}"> {number} </ratedpower2>
98 <ratedrpm2> {number} </ratedrpm2>
99 <ratedaltitude2 unit="{FT | M}"> {number} </ratedaltitude2>
100 <ratedboost3 unit="{INHG | PA | ATM}"> {number} </ratedboost3>
101 <ratedpower3 unit="{HP | WATTS}"> {number} </ratedpower3>
102 <ratedrpm3> {number} </ratedrpm3>
103 <ratedaltitude3 unit="{FT | M}"> {number} </ratedaltitude3>
104 <takeoffboost unit="{INHG | PA | ATM}"> {number} </takeoffboost>
108 <h3>Definition of the piston engine configuration file parameters:</h3>
110 - \b minmp - this value is the nominal idle manifold pressure at sea-level
111 without boost. Along with idlerpm, it determines throttle response slope.
112 - \b maxmp - this value is the nominal maximum manifold pressure at sea-level
113 without boost. Along with maxrpm it determines the resistance of the
114 aircraft intake system. Overridden by air-intake-impedance-factor
115 - \b idlerpm - this value affects the throttle fall off and the engine stops
116 running if it is slowed below 80% of this value. The engine starts
117 running when it reaches 80% of this value.
118 - \b maxrpm - this value is used to calculate air-box resistance and BSFC. It
119 also affects oil pressure among other things.
120 - \b maxhp - this value is the nominal power the engine creates at maxrpm. It
121 will determine bsfc if that tag is not input. It also determines the
123 - \b displacement - this value is used to determine mass air and fuel flow
124 which impacts engine power and cooling.
125 - \b cycles - Designate a 2 or 4 stroke engine. Currently only the 4 stroke
127 - \b bore - cylinder bore is currently unused.
128 - \b stroke - piston stroke is used to determine the mean piston speed. Longer
129 strokes result in an engine that does not work as well at higher RPMs.
130 - \b compression-ratio - the compression ratio affects the change in volumetric
131 efficiency with altitude.
132 - \b sparkfaildrop - this is the percentage drop in horsepower for single
134 - \b static-friction - this value is the power required to turn an engine that
135 is not running. Used to control and slow a windmilling propeller. Choose
136 a small percentage of maxhp.
139 - \b bsfc - Indicated Specific Fuel Consumption. The power produced per unit of
140 fuel. Higher numbers give worse fuel economy. This number may need to be
141 lowered slightly from actual BSFC numbers because some internal engine
142 losses are modeled separately. Typically between 0.3 and 0.5
143 - \b volumetric-efficiency - the nominal volumetric efficiency of the engine.
144 This is the primary way to control fuel flow Boosted engines may require
145 values above 1. Typical engines are 0.80 to 0.82
146 - \b air-intake-impedance-factor - this number is the pressure drop across the
147 intake system. Increasing it reduces available manifold pressure. Also a
148 property for run-time adjustment.
149 - \b ram-air-factor - this number creates increases manifold pressure with an
150 increase in dynamic pressure (aircraft speed).
151 Also a property for run-time adjustment.
154 - \b cylinders - number of cylinders scales the cylinder head mass.
155 - \b cylinder-head-mass - the nominal mass of a cylinder head. A larger value
156 slows changes in engine temperature
157 - \b cooling-factor - this number models the efficiency of the aircraft cooling
158 system. Also a property for run-time adjustment.
160 Supercharge parameters:
161 - \b numboostspeed - zero (or not present) for a naturally-aspirated engine,
162 either 1, 2 or 3 for a boosted engine. This corresponds to the number of
163 supercharger speeds. Merlin XII had 1 speed, Merlin 61 had 2, a late
164 Griffon engine apparently had 3. No known engine more than 3, although
165 some German engines had continuously variable-speed superchargers.
166 - \b boostoverride - unused
167 - \b boostmanual - whether a multispeed supercharger will manually or
168 automatically shift boost speeds. On manual shifting the boost speeds is
169 accomplished by controlling the property propulsion/engine/boostspeed.
170 - \b takeoffboost - boost in psi above sea level ambient. Typically used for
171 takeoff, and emergency situations, generally for not more than five
172 minutes. This is a change in the boost control setting, not the actual
173 supercharger speed, and so would only give extra power below the rated altitude.
174 A typical takeoff boost for an early Merlin was about 12psi, compared
175 with a rated boost of 9psi.
177 When TAKEOFFBOOST is specified in the config file (and is above RATEDBOOST1),
178 the throttle position is interpreted as:
179 - 0 to 0.98 : idle manifold pressure to rated boost (where attainable)
180 - 0.99, 1.0 : takeoff boost (where attainable).
182 The next items are all appended with either 1, 2 or 3 depending on which
183 boostspeed they refer to:
184 - \b ratedboost[123] - the absolute rated boost above sea level ambient
185 (14.7 PSI, 29.92 inHg) for a given boost speed.
187 - \b ratedpower[123] - unused
188 - \b ratedrpm[123] - The rpm at which rated boost is developed
189 - \b ratedaltitude[123] - The altitude up to which the rated boost can be
190 maintained. Up to this altitude the boost is clipped to rated boost or
191 takeoffboost. Beyond this altitude the manifold pressure must drop,
192 since the supercharger is now at maximum unregulated output. The actual
193 pressure multiplier of the supercharger system is calculated at
194 initialization from this value.
196 @author Jon S. Berndt (Engine framework code and framework-related mods)
197 @author Dave Luff (engine operational code)
198 @author David Megginson (initial porting and additional code)
199 @author Ron Jensen (additional engine code)
200 @see Taylor, Charles Fayette, "The Internal Combustion Engine in Theory and Practice"
201 @version $Id: FGPiston.h,v 1.32 2011/10/11 16:16:16 jentron Exp $
204 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
206 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
208 class FGPiston : public FGEngine
212 FGPiston(FGFDMExec* exec, Element* el, int engine_number, struct Inputs& input);
216 std::string GetEngineLabels(const std::string& delimiter);
217 std::string GetEngineValues(const std::string& delimiter);
219 void Calculate(void);
220 double GetPowerAvailable(void) const {return (HP * hptoftlbssec);}
221 double CalcFuelNeed(void);
223 void ResetToIC(void);
224 void SetMagnetos(int magnetos) {Magnetos = magnetos;}
226 double GetEGT(void) const { return EGT_degC; }
227 int GetMagnetos(void) const {return Magnetos;}
229 double getExhaustGasTemp_degF(void) const {return KelvinToFahrenheit(ExhaustGasTemp_degK);}
230 double getManifoldPressure_inHg(void) const {return ManifoldPressure_inHg;}
231 double getCylinderHeadTemp_degF(void) const {return KelvinToFahrenheit(CylinderHeadTemp_degK);}
232 double getOilPressure_psi(void) const {return OilPressure_psi;}
233 double getOilTemp_degF (void) const {return KelvinToFahrenheit(OilTemp_degK);}
234 double getRPM(void) const {return RPM;}
241 double IndicatedHorsePower;
247 void doEngineStartup(void);
248 void doBoostControl(void);
250 void doAirFlow(void);
251 void doFuelFlow(void);
252 void doEnginePower(void);
255 void doOilPressure(void);
256 void doOilTemperature(void);
257 double GetStdPressure100K(double altitude) const;
259 int InitRunning(void);
266 const double rho_fuel; // kg/m^3
267 const double calorific_value_fuel; // J/Kg (approximate)
268 const double Cp_air; // J/KgK
269 const double Cp_fuel; // J/KgK
270 const double standard_pressure; //Pa
273 FGTable *Lookup_Combustion_Efficiency;
274 FGTable *Mixture_Efficiency_Correlation;
279 double MinManifoldPressure_inHg; // Inches Hg
280 double MaxManifoldPressure_inHg; // Inches Hg
281 double MaxManifoldPressure_Percent; // MaxManifoldPressure / 29.92
282 double Displacement; // cubic inches
283 double displacement_SI; // cubic meters
284 double MaxHP; // horsepower
285 double StaticFriction_HP; // horsepower: amount subtracted from final engine power
286 double SparkFailDrop; // drop of power due to spark failure
287 double Cycles; // cycles/power stroke
288 double IdleRPM; // revolutions per minute
289 double MaxRPM; // revolutions per minute
290 double Bore; // inches
291 double Stroke; // inches
292 double Cylinders; // number
293 double CylinderHeadMass; // kilograms
294 double CompressionRatio; // number
295 double Z_airbox; // number representing intake impediance before the throttle
296 double Z_throttle; // number representing slope of throttle impediance
297 double PeakMeanPistonSpeed_fps; // ft/sec speed where intake valves begin to choke. Typically 33-50 fps
298 double RatedMeanPistonSpeed_fps; // ft/sec derived from MaxRPM and stroke.
299 double Ram_Air_Factor; // number
301 double StarterHP; // initial horsepower of starter motor
302 int BoostSpeeds; // Number of super/turbocharger boost speeds - zero implies no turbo/supercharging.
303 int BoostSpeed; // The current boost-speed (zero-based).
304 bool Boosted; // Set true for boosted engine.
305 int BoostManual; // The raw value read in from the config file - should be 1 or 0 - see description below.
306 bool bBoostManual; // Set true if pilot must manually control the boost speed.
307 int BoostOverride; // The raw value read in from the config file - should be 1 or 0 - see description below.
308 bool bBoostOverride; // Set true if pilot override of the boost regulator was fitted.
309 // (Typically called 'war emergency power').
310 bool bTakeoffBoost; // Set true if extra takeoff / emergency boost above rated boost could be attained.
311 // (Typically by extra throttle movement past a mechanical 'gate').
312 double TakeoffBoost; // Sea-level takeoff boost in psi. (if fitted).
313 double RatedBoost[FG_MAX_BOOST_SPEEDS]; // Sea-level rated boost in psi.
314 double RatedAltitude[FG_MAX_BOOST_SPEEDS]; // Altitude at which full boost is reached (boost regulation ends)
315 // and at which power starts to fall with altitude [ft].
316 double RatedRPM[FG_MAX_BOOST_SPEEDS]; // Engine speed at which the rated power for each boost speed is delivered [rpm].
317 double RatedPower[FG_MAX_BOOST_SPEEDS]; // Power at rated throttle position at rated altitude [HP].
318 double BoostSwitchAltitude[FG_MAX_BOOST_SPEEDS - 1]; // Altitude at which switchover (currently assumed automatic)
319 // from one boost speed to next occurs [ft].
320 double BoostSwitchPressure[FG_MAX_BOOST_SPEEDS - 1]; // Pressure at which boost speed switchover occurs [Pa]
321 double BoostMul[FG_MAX_BOOST_SPEEDS]; // Pressure multipier of unregulated supercharger
322 double RatedMAP[FG_MAX_BOOST_SPEEDS]; // Rated manifold absolute pressure [Pa] (BCV clamp)
323 double TakeoffMAP[FG_MAX_BOOST_SPEEDS]; // Takeoff setting manifold absolute pressure [Pa] (BCV clamp)
324 double BoostSwitchHysteresis; // Pa.
329 double TMAP; // Pa - throttle manifold pressure e.g. before the supercharger boost
330 double ISFC; // Indicated specific fuel consumption [lbs/horsepower*hour
333 // Inputs (in addition to those in FGEngine).
335 double TotalDeltaT; // Time in seconds between calls.
336 double p_amb; // Pascals
337 double p_ram; // Pascals
338 double T_amb; // degrees Kelvin
339 double RPM; // revolutions per minute
341 double Cooling_Factor; // normal
347 // Outputs (in addition to those in FGEngine).
350 double volumetric_efficiency;
351 double map_coefficient;
353 double equivalence_ratio;
356 double combustion_efficiency;
357 double ExhaustGasTemp_degK;
359 double ManifoldPressure_inHg;
360 double CylinderHeadTemp_degK;
361 double OilPressure_psi;
363 double MeanPistonSpeed_fps;
365 void Debug(int from);
368 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%