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 <boostmanual> {0 | 1} </boostmanual>
88 <ratedboost1 unit="{INHG | PA | ATM}"> {number} </ratedboost1>
89 <ratedpower1 unit="{HP | WATTS}"> {number} </ratedpower1>
90 <ratedrpm1> {number} </ratedrpm1>
91 <ratedaltitude1 unit="{FT | M}"> {number} </ratedaltitude1>
92 <ratedboost2 unit="{INHG | PA | ATM}"> {number} </ratedboost2>
93 <ratedpower2 unit="{HP | WATTS}"> {number} </ratedpower2>
94 <ratedrpm2> {number} </ratedrpm2>
95 <ratedaltitude2 unit="{FT | M}"> {number} </ratedaltitude2>
96 <ratedboost3 unit="{INHG | PA | ATM}"> {number} </ratedboost3>
97 <ratedpower3 unit="{HP | WATTS}"> {number} </ratedpower3>
98 <ratedrpm3> {number} </ratedrpm3>
99 <ratedaltitude3 unit="{FT | M}"> {number} </ratedaltitude3>
100 <takeoffboost unit="{INHG | PA | ATM}"> {number} </takeoffboost>
101 <air-intake-impedance-factor> {number} </air-intake-impedance-factor>
102 <ram-air-factor> {number} </ram-air-factor>
107 Additional elements are required for a supercharged engine. These can be
108 left off a non-supercharged engine, ie. the changes are all backward
109 compatible at present.
111 - NUMBOOSTSPEEDS - zero (or not present) for a naturally-aspirated engine,
112 either 1, 2 or 3 for a boosted engine. This corresponds to the number of
113 supercharger speeds. Merlin XII had 1 speed, Merlin 61 had 2, a late
114 Griffon engine apparently had 3. No known engine more than 3, although
115 some German engines apparently had a continuously variable-speed
118 - BOOSTOVERRIDE - whether the boost pressure control system (either a boost
119 control valve for superchargers or wastegate for turbochargers) can be
120 overriden by the pilot. During wartime this was commonly possible, and
121 known as "War Emergency Power" by the Brits. 1 or 0 in the config file.
122 This isn't implemented in the model yet though, there would need to be
123 some way of getting the boost control cutout lever position (on or off)
124 from FlightGear first.
126 - BOOSTMANUAL - whether a multispeed supercharger will manually or
127 automatically shift boost speeds. On manual shifting the boost speeds
128 is accomplished by controling propulsion/engine/boostspeed
130 - The next items are all appended with either 1, 2 or 3 depending on which
131 boost speed they refer to, eg RATEDBOOST1. The rated values seems to have
132 been a common convention at the time to express the maximum continuously
133 available power, and the conditions to attain that power.
135 - RATEDBOOST[123] - the absolute rated boost above sea level ambient for a
136 given boost speed, in psi. Eg the Merlin XII had a rated boost of 9psi,
137 giving approximately 42inHg manifold pressure up to the rated altitude.
139 - RATEDALTITUDE[123] - The altitude up to which rated boost can be
140 maintained. Up to this altitude the boost is maintained constant for a
141 given throttle position by the BCV or wastegate. Beyond this altitude the
142 manifold pressure must drop, since the supercharger is now at maximum
143 unregulated output. The actual pressure multiplier of the supercharger
144 system is calculated at initialisation from this value.
146 - RATEDPOWER[123] - The power developed at rated boost at rated altitude at
149 - RATEDRPM[123] - The rpm at which rated power is developed.
151 - TAKEOFFBOOST - Takeoff boost in psi above ambient. Many aircraft had an
152 extra boost setting beyond rated boost, but not totally uncontrolled as in
153 the already mentioned boost-control-cutout, typically attained by pushing
154 the throttle past a mechanical 'gate' preventing its inadvertant use. This
155 was typically used for takeoff, and emergency situations, generally for
156 not more than five minutes. This is a change in the boost control
157 setting, not the actual supercharger speed, and so would only give extra
158 power below the rated altitude. When TAKEOFFBOOST is specified in the
159 config file (and is above RATEDBOOST1), then the throttle position is
162 - 0 to 0.95 : idle manifold pressure to rated boost (where attainable)
163 - 0.96, 0.97, 0.98 : rated boost (where attainable).
164 - 0.99, 1.0 : takeoff boost (where attainable).
166 A typical takeoff boost for an earlyish Merlin was about 12psi, compared
167 with a rated boost of 9psi.
169 It is quite possible that other boost control settings could have been used
170 on some aircraft, or that takeoff/extra boost could have activated by other
171 means than pushing the throttle full forward through a gate, but this will
174 Note that MAXMP is still the non-boosted max manifold pressure even for
175 boosted engines - effectively this is simply a measure of the pressure drop
176 through the fully open throttle.
179 @author Jon S. Berndt (Engine framework code and framework-related mods)
180 @author Dave Luff (engine operational code)
181 @author David Megginson (initial porting and additional code)
182 @author Ron Jensen (additional engine code)
186 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
188 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
190 class FGPiston : public FGEngine
194 FGPiston(FGFDMExec* exec, Element* el, int engine_number);
198 string GetEngineLabels(string delimeter);
199 string GetEngineValues(string delimeter);
201 double Calculate(void);
202 double GetPowerAvailable(void) {return PowerAvailable;}
203 double CalcFuelNeed(void);
205 void ResetToIC(void);
206 void SetMagnetos(int magnetos) {Magnetos = magnetos;}
208 double GetEGT(void) { return EGT_degC; }
209 int GetMagnetos(void) {return Magnetos;}
211 double getExhaustGasTemp_degF(void) {return KelvinToFahrenheit(ExhaustGasTemp_degK);}
212 double getManifoldPressure_inHg(void) const {return ManifoldPressure_inHg;}
213 double getCylinderHeadTemp_degF(void) {return KelvinToFahrenheit(CylinderHeadTemp_degK);}
214 double getOilPressure_psi(void) const {return OilPressure_psi;}
215 double getOilTemp_degF (void) {return KelvinToFahrenheit(OilTemp_degK);}
216 double getRPM(void) {return RPM;}
219 double ThrottleAngle;
224 double IndicatedHorsePower;
228 double SpeedIntercept;
229 double AltitudeSlope;
230 double PowerAvailable;
235 void doEngineStartup(void);
236 void doBoostControl(void);
238 void doAirFlow(void);
239 void doFuelFlow(void);
240 void doEnginePower(void);
243 void doOilPressure(void);
244 void doOilTemperature(void);
246 int InitRunning(void);
253 const double rho_fuel; // kg/m^3
254 const double calorific_value_fuel; // W/Kg (approximate)
255 const double Cp_air; // J/KgK
256 const double Cp_fuel; // J/KgK
257 const double standard_pressure; //Pa
260 FGTable *Lookup_Combustion_Efficiency;
261 FGTable *Mixture_Efficiency_Correlation;
266 double MinManifoldPressure_inHg; // Inches Hg
267 double MaxManifoldPressure_inHg; // Inches Hg
268 double MaxManifoldPressure_Percent; // MaxManifoldPressure / 29.92
269 double Displacement; // cubic inches
270 double displacement_SI; // cubic meters
271 double MaxHP; // horsepower
272 double SparkFailDrop; // drop of power due to spark failure
273 double Cycles; // cycles/power stroke
274 double IdleRPM; // revolutions per minute
275 double MaxRPM; // revolutions per minute
276 double Bore; // inches
277 double Stroke; // inches
278 double Cylinders; // number
279 double CompressionRatio; // number
280 double Z_airbox; // number representing intake impediance before the throttle
281 double Z_throttle; // number representing slope of throttle impediance
282 double PeakMeanPistonSpeed_fps; // ft/sec speed where intake valves begin to choke. Typically 33-50 fps
283 double RatedMeanPistonSpeed_fps; // ft/sec derived from MaxRPM and stroke.
284 double Ram_Air_Factor; // number
286 double StarterHP; // initial horsepower of starter motor
287 int BoostSpeeds; // Number of super/turbocharger boost speeds - zero implies no turbo/supercharging.
288 int BoostSpeed; // The current boost-speed (zero-based).
289 bool Boosted; // Set true for boosted engine.
290 int BoostManual; // The raw value read in from the config file - should be 1 or 0 - see description below.
291 bool bBoostManual; // Set true if pilot must manually control the boost speed.
292 int BoostOverride; // The raw value read in from the config file - should be 1 or 0 - see description below.
293 bool bBoostOverride; // Set true if pilot override of the boost regulator was fitted.
294 // (Typically called 'war emergency power').
295 bool bTakeoffBoost; // Set true if extra takeoff / emergency boost above rated boost could be attained.
296 // (Typically by extra throttle movement past a mechanical 'gate').
297 double TakeoffBoost; // Sea-level takeoff boost in psi. (if fitted).
298 double RatedBoost[FG_MAX_BOOST_SPEEDS]; // Sea-level rated boost in psi.
299 double RatedAltitude[FG_MAX_BOOST_SPEEDS]; // Altitude at which full boost is reached (boost regulation ends)
300 // and at which power starts to fall with altitude [ft].
301 double RatedRPM[FG_MAX_BOOST_SPEEDS]; // Engine speed at which the rated power for each boost speed is delivered [rpm].
302 double RatedPower[FG_MAX_BOOST_SPEEDS]; // Power at rated throttle position at rated altitude [HP].
303 double BoostSwitchAltitude[FG_MAX_BOOST_SPEEDS - 1]; // Altitude at which switchover (currently assumed automatic)
304 // from one boost speed to next occurs [ft].
305 double BoostSwitchPressure[FG_MAX_BOOST_SPEEDS - 1]; // Pressure at which boost speed switchover occurs [Pa]
306 double BoostMul[FG_MAX_BOOST_SPEEDS]; // Pressure multipier of unregulated supercharger
307 double RatedMAP[FG_MAX_BOOST_SPEEDS]; // Rated manifold absolute pressure [Pa] (BCV clamp)
308 double TakeoffMAP[FG_MAX_BOOST_SPEEDS]; // Takeoff setting manifold absolute pressure [Pa] (BCV clamp)
309 double BoostSwitchHysteresis; // Pa.
314 double TMAP; // Pa - throttle manifold pressure e.g. before the supercharger boost
315 double ISFC; // Indicated specific fuel consumption [lbs/horsepower*hour
318 // Inputs (in addition to those in FGEngine).
320 double p_amb; // Pascals
321 double p_ram; // Pascals
322 double T_amb; // degrees Kelvin
323 double RPM; // revolutions per minute
330 // Outputs (in addition to those in FGEngine).
333 double volumetric_efficiency;
334 double map_coefficient;
336 double equivalence_ratio;
339 double combustion_efficiency;
340 double ExhaustGasTemp_degK;
342 double ManifoldPressure_inHg;
343 double CylinderHeadTemp_degK;
344 double OilPressure_psi;
346 double MeanPistonSpeed_fps;
348 void Debug(int from);
351 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%