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>
44 #include <input_output/FGXMLElement.h>
46 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
48 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
50 #define ID_PISTON "$Id$";
51 #define FG_MAX_BOOST_SPEEDS 3
53 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
55 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
59 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
61 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
63 /** Models Dave Luff's Turbo/Supercharged Piston engine model.
65 <h3>Configuration File Format:</h3>
68 <piston_engine name="{string}">
69 <minmp unit="{INHG | PA | ATM}"> {number} </minmp> <!-- Depricated -->
70 <maxmp unit="{INHG | PA | ATM}"> {number} </maxmp>
71 <displacement unit="{IN3 | LTR | CC}"> {number} </displacement>
72 <bore unit="{IN | M}"> {number} </bore>
73 <stroke unit="{IN | M}"> {number} </stroke>
74 <cylinders> {number} </cylinders>
75 <compression-ratio> {number} </compression-ratio>
76 <sparkfaildrop> {number} </sparkfaildrop>
77 <maxhp unit="{HP | WATTS}"> {number} </maxhp>
78 <cycles> {number} </cycles>
79 <idlerpm> {number} </idlerpm>
80 <maxrpm> {number} </maxrpm>
81 <maxthrottle> {number} </maxthrottle>
82 <minthrottle> {number} </minthrottle>
83 <bsfc unit="{LBS/HP*HR | "KG/KW*HR"}"> {number} </bsfc>
84 <volumetric_efficiency> {number} </volumetric_efficiency>
85 <numboostspeeds> {number} </numboostspeeds>
86 <boostoverride> {0 | 1} </boostoverride>
87 <ratedboost1 unit="{INHG | PA | ATM}"> {number} </ratedboost1>
88 <ratedpower1 unit="{HP | WATTS}"> {number} </ratedpower1>
89 <ratedrpm1> {number} </ratedrpm1>
90 <ratedaltitude1 unit="{FT | M}"> {number} </ratedaltitude1>
91 <ratedboost2 unit="{INHG | PA | ATM}"> {number} </ratedboost2>
92 <ratedpower2 unit="{HP | WATTS}"> {number} </ratedpower2>
93 <ratedrpm2> {number} </ratedrpm2>
94 <ratedaltitude2 unit="{FT | M}"> {number} </ratedaltitude2>
95 <ratedboost3 unit="{INHG | PA | ATM}"> {number} </ratedboost3>
96 <ratedpower3 unit="{HP | WATTS}"> {number} </ratedpower3>
97 <ratedrpm3> {number} </ratedrpm3>
98 <ratedaltitude3 unit="{FT | M}"> {number} </ratedaltitude3>
99 <takeoffboost unit="{INHG | PA | ATM}"> {number} </takeoffboost>
104 Additional elements are required for a supercharged engine. These can be
105 left off a non-supercharged engine, ie. the changes are all backward
106 compatible at present.
108 - NUMBOOSTSPEEDS - zero (or not present) for a naturally-aspirated engine,
109 either 1, 2 or 3 for a boosted engine. This corresponds to the number of
110 supercharger speeds. Merlin XII had 1 speed, Merlin 61 had 2, a late
111 Griffon engine apparently had 3. No known engine more than 3, although
112 some German engines apparently had a continuously variable-speed
115 - BOOSTOVERRIDE - whether the boost pressure control system (either a boost
116 control valve for superchargers or wastegate for turbochargers) can be
117 overriden by the pilot. During wartime this was commonly possible, and
118 known as "War Emergency Power" by the Brits. 1 or 0 in the config file.
119 This isn't implemented in the model yet though, there would need to be
120 some way of getting the boost control cutout lever position (on or off)
121 from FlightGear first.
123 - The next items are all appended with either 1, 2 or 3 depending on which
124 boost speed they refer to, eg RATEDBOOST1. The rated values seems to have
125 been a common convention at the time to express the maximum continuously
126 available power, and the conditions to attain that power.
128 - RATEDBOOST[123] - the absolute rated boost above sea level ambient for a
129 given boost speed, in psi. Eg the Merlin XII had a rated boost of 9psi,
130 giving approximately 42inHg manifold pressure up to the rated altitude.
132 - RATEDALTITUDE[123] - The altitude up to which rated boost can be
133 maintained. Up to this altitude the boost is maintained constant for a
134 given throttle position by the BCV or wastegate. Beyond this altitude the
135 manifold pressure must drop, since the supercharger is now at maximum
136 unregulated output. The actual pressure multiplier of the supercharger
137 system is calculated at initialisation from this value.
139 - RATEDPOWER[123] - The power developed at rated boost at rated altitude at
142 - RATEDRPM[123] - The rpm at which rated power is developed.
144 - TAKEOFFBOOST - Takeoff boost in psi above ambient. Many aircraft had an
145 extra boost setting beyond rated boost, but not totally uncontrolled as in
146 the already mentioned boost-control-cutout, typically attained by pushing
147 the throttle past a mechanical 'gate' preventing its inadvertant use. This
148 was typically used for takeoff, and emergency situations, generally for
149 not more than five minutes. This is a change in the boost control
150 setting, not the actual supercharger speed, and so would only give extra
151 power below the rated altitude. When TAKEOFFBOOST is specified in the
152 config file (and is above RATEDBOOST1), then the throttle position is
155 - 0 to 0.95 : idle manifold pressure to rated boost (where attainable)
156 - 0.96, 0.97, 0.98 : rated boost (where attainable).
157 - 0.99, 1.0 : takeoff boost (where attainable).
159 A typical takeoff boost for an earlyish Merlin was about 12psi, compared
160 with a rated boost of 9psi.
162 It is quite possible that other boost control settings could have been used
163 on some aircraft, or that takeoff/extra boost could have activated by other
164 means than pushing the throttle full forward through a gate, but this will
167 Note that MAXMP is still the non-boosted max manifold pressure even for
168 boosted engines - effectively this is simply a measure of the pressure drop
169 through the fully open throttle.
172 @author Jon S. Berndt (Engine framework code and framework-related mods)
173 @author Dave Luff (engine operational code)
174 @author David Megginson (initial porting and additional code)
175 @author Ron Jensen (additional engine code)
179 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
181 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
183 class FGPiston : public FGEngine
187 FGPiston(FGFDMExec* exec, Element* el, int engine_number);
191 string GetEngineLabels(string delimeter);
192 string GetEngineValues(string delimeter);
194 double Calculate(void);
195 double GetPowerAvailable(void) {return PowerAvailable;}
196 double CalcFuelNeed(void);
198 void ResetToIC(void);
199 void SetMagnetos(int magnetos) {Magnetos = magnetos;}
201 double GetEGT(void) { return EGT_degC; }
202 int GetMagnetos(void) {return Magnetos;}
204 double getExhaustGasTemp_degF(void) {return KelvinToFahrenheit(ExhaustGasTemp_degK);}
205 double getManifoldPressure_inHg(void) const {return ManifoldPressure_inHg;}
206 double getCylinderHeadTemp_degF(void) {return KelvinToFahrenheit(CylinderHeadTemp_degK);}
207 double getOilPressure_psi(void) const {return OilPressure_psi;}
208 double getOilTemp_degF (void) {return KelvinToFahrenheit(OilTemp_degK);}
209 double getRPM(void) {return RPM;}
212 double ThrottleAngle;
217 double IndicatedHorsePower;
221 double SpeedIntercept;
222 double AltitudeSlope;
223 double PowerAvailable;
228 void doEngineStartup(void);
229 void doBoostControl(void);
231 void doAirFlow(void);
232 void doFuelFlow(void);
233 void doEnginePower(void);
236 void doOilPressure(void);
237 void doOilTemperature(void);
239 int InitRunning(void);
246 const double rho_fuel; // kg/m^3
247 const double calorific_value_fuel; // W/Kg (approximate)
248 const double Cp_air; // J/KgK
249 const double Cp_fuel; // J/KgK
251 FGTable *Lookup_Combustion_Efficiency;
252 FGTable *Mixture_Efficiency_Correlation;
257 double MinManifoldPressure_inHg; // Inches Hg
258 double MaxManifoldPressure_inHg; // Inches Hg
259 double MaxManifoldPressure_Percent; // MaxManifoldPressure / 29.92
260 double Displacement; // cubic inches
261 double displacement_SI; // cubic meters
262 double MaxHP; // horsepower
263 double SparkFailDrop; // drop of power due to spark failure
264 double Cycles; // cycles/power stroke
265 double IdleRPM; // revolutions per minute
266 double MaxRPM; // revolutions per minute
267 double Bore; // inches
268 double Stroke; // inches
269 double Cylinders; // number
270 double CompressionRatio; // number
272 double StarterHP; // initial horsepower of starter motor
273 int BoostSpeeds; // Number of super/turbocharger boost speeds - zero implies no turbo/supercharging.
274 int BoostSpeed; // The current boost-speed (zero-based).
275 bool Boosted; // Set true for boosted engine.
276 int BoostOverride; // The raw value read in from the config file - should be 1 or 0 - see description below.
277 bool bBoostOverride; // Set true if pilot override of the boost regulator was fitted.
278 // (Typically called 'war emergency power').
279 bool bTakeoffBoost; // Set true if extra takeoff / emergency boost above rated boost could be attained.
280 // (Typically by extra throttle movement past a mechanical 'gate').
281 double TakeoffBoost; // Sea-level takeoff boost in psi. (if fitted).
282 double RatedBoost[FG_MAX_BOOST_SPEEDS]; // Sea-level rated boost in psi.
283 double RatedAltitude[FG_MAX_BOOST_SPEEDS]; // Altitude at which full boost is reached (boost regulation ends)
284 // and at which power starts to fall with altitude [ft].
285 double RatedRPM[FG_MAX_BOOST_SPEEDS]; // Engine speed at which the rated power for each boost speed is delivered [rpm].
286 double RatedPower[FG_MAX_BOOST_SPEEDS]; // Power at rated throttle position at rated altitude [HP].
287 double BoostSwitchAltitude[FG_MAX_BOOST_SPEEDS - 1]; // Altitude at which switchover (currently assumed automatic)
288 // from one boost speed to next occurs [ft].
289 double BoostSwitchPressure[FG_MAX_BOOST_SPEEDS - 1]; // Pressure at which boost speed switchover occurs [Pa]
290 double BoostMul[FG_MAX_BOOST_SPEEDS]; // Pressure multipier of unregulated supercharger
291 double RatedMAP[FG_MAX_BOOST_SPEEDS]; // Rated manifold absolute pressure [Pa] (BCV clamp)
292 double TakeoffMAP[FG_MAX_BOOST_SPEEDS]; // Takeoff setting manifold absolute pressure [Pa] (BCV clamp)
293 double BoostSwitchHysteresis; // Pa.
298 double TMAP; // Pa - throttle manifold pressure e.g. before the supercharger boost
299 double ISFC; // Indicated specific fuel consumption [lbs/horsepower*hour
302 // Inputs (in addition to those in FGEngine).
304 double p_amb; // Pascals
305 double T_amb; // degrees Kelvin
306 double RPM; // revolutions per minute
313 // Outputs (in addition to those in FGEngine).
316 double volumetric_efficiency;
317 double map_coefficient;
319 double equivalence_ratio;
322 double combustion_efficiency;
323 double ExhaustGasTemp_degK;
325 double ManifoldPressure_inHg;
326 double CylinderHeadTemp_degK;
327 double OilPressure_psi;
329 double MeanPistonSpeed_fps;
331 void Debug(int from);
334 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%