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 1.24 2010/08/21 18:08:13 jberndt Exp $";
50 #define FG_MAX_BOOST_SPEEDS 3
52 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
54 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
58 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
60 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
62 /** Models Dave Luff's Turbo/Supercharged Piston engine 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 <displacement unit="{IN3 | LTR | CC}"> {number} </displacement>
71 <bore unit="{IN | M}"> {number} </bore>
72 <stroke unit="{IN | M}"> {number} </stroke>
73 <cylinders> {number} </cylinders>
74 <compression-ratio> {number} </compression-ratio>
75 <sparkfaildrop> {number} </sparkfaildrop>
76 <maxhp unit="{HP | WATTS}"> {number} </maxhp>
77 <cycles> {number} </cycles>
78 <idlerpm> {number} </idlerpm>
79 <maxrpm> {number} </maxrpm>
80 <maxthrottle> {number} </maxthrottle>
81 <minthrottle> {number} </minthrottle>
82 <bsfc unit="{LBS/HP*HR | "KG/KW*HR"}"> {number} </bsfc>
83 <volumetric-efficiency> {number} </volumetric-efficiency>
84 <dynamic-fmep unit="{INHG | PA | ATM}"> {number} </dynamic-fmep>
85 <static-fmep unit="{INHG | PA | ATM}"> {number} </static-fmep>
86 <numboostspeeds> {number} </numboostspeeds>
87 <boostoverride> {0 | 1} </boostoverride>
88 <boostmanual> {0 | 1} </boostmanual>
89 <ratedboost1 unit="{INHG | PA | ATM}"> {number} </ratedboost1>
90 <ratedpower1 unit="{HP | WATTS}"> {number} </ratedpower1>
91 <ratedrpm1> {number} </ratedrpm1>
92 <ratedaltitude1 unit="{FT | M}"> {number} </ratedaltitude1>
93 <ratedboost2 unit="{INHG | PA | ATM}"> {number} </ratedboost2>
94 <ratedpower2 unit="{HP | WATTS}"> {number} </ratedpower2>
95 <ratedrpm2> {number} </ratedrpm2>
96 <ratedaltitude2 unit="{FT | M}"> {number} </ratedaltitude2>
97 <ratedboost3 unit="{INHG | PA | ATM}"> {number} </ratedboost3>
98 <ratedpower3 unit="{HP | WATTS}"> {number} </ratedpower3>
99 <ratedrpm3> {number} </ratedrpm3>
100 <ratedaltitude3 unit="{FT | M}"> {number} </ratedaltitude3>
101 <takeoffboost unit="{INHG | PA | ATM}"> {number} </takeoffboost>
102 <air-intake-impedance-factor> {number} </air-intake-impedance-factor>
103 <ram-air-factor> {number} </ram-air-factor>
108 Additional elements are required for a supercharged engine. These can be
109 left off a non-supercharged engine, ie. the changes are all backward
110 compatible at present.
112 - NUMBOOSTSPEEDS - zero (or not present) for a naturally-aspirated engine,
113 either 1, 2 or 3 for a boosted engine. This corresponds to the number of
114 supercharger speeds. Merlin XII had 1 speed, Merlin 61 had 2, a late
115 Griffon engine apparently had 3. No known engine more than 3, although
116 some German engines apparently had a continuously variable-speed
119 - BOOSTOVERRIDE - whether the boost pressure control system (either a boost
120 control valve for superchargers or wastegate for turbochargers) can be
121 overriden by the pilot. During wartime this was commonly possible, and
122 known as "War Emergency Power" by the Brits. 1 or 0 in the config file.
123 This isn't implemented in the model yet though, there would need to be
124 some way of getting the boost control cutout lever position (on or off)
125 from FlightGear first.
127 - BOOSTMANUAL - whether a multispeed supercharger will manually or
128 automatically shift boost speeds. On manual shifting the boost speeds
129 is accomplished by controling propulsion/engine/boostspeed
131 - The next items are all appended with either 1, 2 or 3 depending on which
132 boost speed they refer to, eg RATEDBOOST1. The rated values seems to have
133 been a common convention at the time to express the maximum continuously
134 available power, and the conditions to attain that power.
136 - RATEDBOOST[123] - the absolute rated boost above sea level ambient for a
137 given boost speed, in psi. Eg the Merlin XII had a rated boost of 9psi,
138 giving approximately 42inHg manifold pressure up to the rated altitude.
140 - RATEDALTITUDE[123] - The altitude up to which rated boost can be
141 maintained. Up to this altitude the boost is maintained constant for a
142 given throttle position by the BCV or wastegate. Beyond this altitude the
143 manifold pressure must drop, since the supercharger is now at maximum
144 unregulated output. The actual pressure multiplier of the supercharger
145 system is calculated at initialisation from this value.
147 - RATEDPOWER[123] - The power developed at rated boost at rated altitude at
150 - RATEDRPM[123] - The rpm at which rated power is developed.
152 - TAKEOFFBOOST - Takeoff boost in psi above ambient. Many aircraft had an
153 extra boost setting beyond rated boost, but not totally uncontrolled as in
154 the already mentioned boost-control-cutout, typically attained by pushing
155 the throttle past a mechanical 'gate' preventing its inadvertant use. This
156 was typically used for takeoff, and emergency situations, generally for
157 not more than five minutes. This is a change in the boost control
158 setting, not the actual supercharger speed, and so would only give extra
159 power below the rated altitude. When TAKEOFFBOOST is specified in the
160 config file (and is above RATEDBOOST1), then the throttle position is
163 - 0 to 0.95 : idle manifold pressure to rated boost (where attainable)
164 - 0.96, 0.97, 0.98 : rated boost (where attainable).
165 - 0.99, 1.0 : takeoff boost (where attainable).
167 A typical takeoff boost for an earlyish Merlin was about 12psi, compared
168 with a rated boost of 9psi.
170 It is quite possible that other boost control settings could have been used
171 on some aircraft, or that takeoff/extra boost could have activated by other
172 means than pushing the throttle full forward through a gate, but this will
175 Note that MAXMP is still the non-boosted max manifold pressure even for
176 boosted engines - effectively this is simply a measure of the pressure drop
177 through the fully open throttle.
180 @author Jon S. Berndt (Engine framework code and framework-related mods)
181 @author Dave Luff (engine operational code)
182 @author David Megginson (initial porting and additional code)
183 @author Ron Jensen (additional engine code)
184 @version $Id: FGPiston.h,v 1.24 2010/08/21 18:08:13 jberndt Exp $
187 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
189 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
191 class FGPiston : public FGEngine
195 FGPiston(FGFDMExec* exec, Element* el, int engine_number);
199 std::string GetEngineLabels(const std::string& delimiter);
200 std::string GetEngineValues(const std::string& delimiter);
202 void Calculate(void);
203 double GetPowerAvailable(void) {return PowerAvailable;}
204 double CalcFuelNeed(void);
206 void ResetToIC(void);
207 void SetMagnetos(int magnetos) {Magnetos = magnetos;}
209 double GetEGT(void) { return EGT_degC; }
210 int GetMagnetos(void) {return Magnetos;}
212 double getExhaustGasTemp_degF(void) {return KelvinToFahrenheit(ExhaustGasTemp_degK);}
213 double getManifoldPressure_inHg(void) const {return ManifoldPressure_inHg;}
214 double getCylinderHeadTemp_degF(void) {return KelvinToFahrenheit(CylinderHeadTemp_degK);}
215 double getOilPressure_psi(void) const {return OilPressure_psi;}
216 double getOilTemp_degF (void) {return KelvinToFahrenheit(OilTemp_degK);}
217 double getRPM(void) {return RPM;}
224 double IndicatedHorsePower;
229 double PowerAvailable;
234 void doEngineStartup(void);
235 void doBoostControl(void);
237 void doAirFlow(void);
238 void doFuelFlow(void);
239 void doEnginePower(void);
242 void doOilPressure(void);
243 void doOilTemperature(void);
245 int InitRunning(void);
252 const double rho_fuel; // kg/m^3
253 const double calorific_value_fuel; // W/Kg (approximate)
254 const double Cp_air; // J/KgK
255 const double Cp_fuel; // J/KgK
256 const double standard_pressure; //Pa
259 FGTable *Lookup_Combustion_Efficiency;
260 FGTable *Mixture_Efficiency_Correlation;
265 double MinManifoldPressure_inHg; // Inches Hg
266 double MaxManifoldPressure_inHg; // Inches Hg
267 double MaxManifoldPressure_Percent; // MaxManifoldPressure / 29.92
268 double Displacement; // cubic inches
269 double displacement_SI; // cubic meters
270 double MaxHP; // horsepower
271 double SparkFailDrop; // drop of power due to spark failure
272 double Cycles; // cycles/power stroke
273 double IdleRPM; // revolutions per minute
274 double MaxRPM; // revolutions per minute
275 double Bore; // inches
276 double Stroke; // inches
277 double Cylinders; // number
278 double CompressionRatio; // number
279 double Z_airbox; // number representing intake impediance before the throttle
280 double Z_throttle; // number representing slope of throttle impediance
281 double PeakMeanPistonSpeed_fps; // ft/sec speed where intake valves begin to choke. Typically 33-50 fps
282 double RatedMeanPistonSpeed_fps; // ft/sec derived from MaxRPM and stroke.
283 double Ram_Air_Factor; // number
285 double StarterHP; // initial horsepower of starter motor
286 int BoostSpeeds; // Number of super/turbocharger boost speeds - zero implies no turbo/supercharging.
287 int BoostSpeed; // The current boost-speed (zero-based).
288 bool Boosted; // Set true for boosted engine.
289 int BoostManual; // The raw value read in from the config file - should be 1 or 0 - see description below.
290 bool bBoostManual; // Set true if pilot must manually control the boost speed.
291 int BoostOverride; // The raw value read in from the config file - should be 1 or 0 - see description below.
292 bool bBoostOverride; // Set true if pilot override of the boost regulator was fitted.
293 // (Typically called 'war emergency power').
294 bool bTakeoffBoost; // Set true if extra takeoff / emergency boost above rated boost could be attained.
295 // (Typically by extra throttle movement past a mechanical 'gate').
296 double TakeoffBoost; // Sea-level takeoff boost in psi. (if fitted).
297 double RatedBoost[FG_MAX_BOOST_SPEEDS]; // Sea-level rated boost in psi.
298 double RatedAltitude[FG_MAX_BOOST_SPEEDS]; // Altitude at which full boost is reached (boost regulation ends)
299 // and at which power starts to fall with altitude [ft].
300 double RatedRPM[FG_MAX_BOOST_SPEEDS]; // Engine speed at which the rated power for each boost speed is delivered [rpm].
301 double RatedPower[FG_MAX_BOOST_SPEEDS]; // Power at rated throttle position at rated altitude [HP].
302 double BoostSwitchAltitude[FG_MAX_BOOST_SPEEDS - 1]; // Altitude at which switchover (currently assumed automatic)
303 // from one boost speed to next occurs [ft].
304 double BoostSwitchPressure[FG_MAX_BOOST_SPEEDS - 1]; // Pressure at which boost speed switchover occurs [Pa]
305 double BoostMul[FG_MAX_BOOST_SPEEDS]; // Pressure multipier of unregulated supercharger
306 double RatedMAP[FG_MAX_BOOST_SPEEDS]; // Rated manifold absolute pressure [Pa] (BCV clamp)
307 double TakeoffMAP[FG_MAX_BOOST_SPEEDS]; // Takeoff setting manifold absolute pressure [Pa] (BCV clamp)
308 double BoostSwitchHysteresis; // Pa.
313 double TMAP; // Pa - throttle manifold pressure e.g. before the supercharger boost
314 double ISFC; // Indicated specific fuel consumption [lbs/horsepower*hour
317 // Inputs (in addition to those in FGEngine).
319 double p_amb; // Pascals
320 double p_ram; // Pascals
321 double T_amb; // degrees Kelvin
322 double RPM; // revolutions per minute
329 // Outputs (in addition to those in FGEngine).
332 double volumetric_efficiency;
333 double map_coefficient;
335 double equivalence_ratio;
338 double combustion_efficiency;
339 double ExhaustGasTemp_degK;
341 double ManifoldPressure_inHg;
342 double CylinderHeadTemp_degK;
343 double OilPressure_psi;
345 double MeanPistonSpeed_fps;
347 void Debug(int from);
350 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%