Re: [Flightgear-devel] JSBSim Piston Engine Idle
On Saturday 08 December 2012 12:12:23 Ron Jensen wrote: I took a quick look through the FGData Aircraft directory today and came up with a list of some 27 JSBSim piston engines that still seem to be using either the old aeromatic default values for idle manifold pressure (minmp) or suspiciously low values. As time permits this week I intend to take a deeper look at this list and adjust the minmp value as seems appropriate, if there are no objections. I know a couple of engines have different versions in other repositories (JSBSim or personal hangers) that are updated and just need to be copied into FGData. Ron Some of this work is done and was committed today, but there are still a dozen engines left to check, I will try to complete those as time permits. Thanks, Ron Done: Dragonfly/Engines/Rotax582.xml: minmp unit=INHG 2.1 /minmp Raised to 7.5, Lowered map lag to 0.1, lowered static friction to 0.5. flight test good Aerocar/Engines/Lycoming_O-290.xml: minmp unit=INHG 6.0 /minmp Raised to 10.1, flight test OK, propeller loads too much to reach 2800 RPM Boeing314/Engines/WrightGR-2600.xml: minmp unit=INHG 6.0 /minmp Raised to 10.0, flight test OK, propeller configuration questionable c150/Engines/eng_O-200.xml: minmp unit=INHG 6.0 /minmp Copied my development engine over. Tweaked propeller and FDM for fair flight numbers. Needs more work. c172r/Engines/engIO360C.xml: minmp unit=INHG 6.5 /minmp Raised to 10.0, flight test SKIPPED c182/Engines/engIO540AB1A5.xml: minmp unit=INHG 6.5 /minmp Raised to 10.0, flight test not so great, FDM needs work. c310/Engines/engIO470D.xml: minmp unit=INHG 6.5 /minmp Raised to 9.3, flight test good c310u3a/Engines/engIO470D.xml: minmp unit=INHG 6.5 /minmp Raised to 9.3, flight test good dc2/Engines/R-1820-R52.xml: minmp unit=INHG 6.0 /minmp Raised to 9.8, flight test good flash2a/Engines/503.xml: minmp unit=INHG 2.0 /minmp Rewrote engine and propeller configurations. flight test good Won't fix: an2/Engine/ASH-62IR.xml: minmp unit=INHG 5.0 /minmp Seems O.K., can't get it to start, too much non-standard stuff in the system configuration G-164/Engines/R-1340-AN1.xml:minmp unit=INHG 7.0 /minmp Dromader/Engine/engine_Asz-62IRM18.xml: minmp unit=INHG 5.0 /minmp This stalls out at min throttle, but it may be intended by the author. Skyranger/Engines/rotax.xml: minmp unit=INHG 6.0 /minmp Primarily a YASim model, jsbsim just an aeromatic shell, won't touch. c182rg/Engines/engIO540AB1A5.xml:minmp unit=INHG 6.5 /minmp Took my name off this, won't touch. Probably won't idle: dc6/Engines/CB17.xml:minmp unit=INHG 6.0 /minmp dc6/Engines/eng_R-2800.xml: minmp unit=INHG 6.5 /minmp fkdr1/Engines/Oberursel-UrII.xml:minmp unit=INHG 6.0 /minmp Lockheed1049/Engines/WrightCyclone-975C18CB1.xml: minmp unit=INHG 6.0 /minmp Lockheed1049h/Engines/WrightCyclone-972TC18DA3.xml: minmp unit=INHG 6.0 /minmp Lockheed1049h/Engines/WrightCyclone-975C18CB1.xml: minmp unit=INHG 6.0 /minmp Noratlas/Engines/Bristol-739.xml: minmp unit=INHG6.0 /minmp ogel/Engines/200hp-jsbsim-2.0.xml: minmp unit=INHG6.0 /minmp P-38-Lightning/Engines/Allison.xml: minmp unit=INHG6.0 /minmp p51d/Engines/Packard-V-1650-7.xml: minmp unit=INHG4.0 /minmp PBY-Catalina/Engines/PBY-6_engine-new.xml: minmp unit=INHG 6.0 /minmp Storch/Engines/Argus_As_10.xml: minmp unit=INHG6.0 /minmp Assumed Good: A6M2/Engines/Sakae-Type12.xml: minmp unit=INHG 10.5 /minmp b29/Engines/eng_R3350.xml: minmp unit=INHG 12.0 /minmp c172p/Engines/eng_io320.xml: minmp unit=INHG 8.3 /minmp C684/Engines/6Pfi.xml: !--minmp unit=INHG 6.0 /minmp-- Cap10B/Engine/LycomingIO360B2F.xml: minmp unit=INHG 12.0 /minmp Cessna337/Engines/engine_IO360C.xml: minmp unit=INHG 15.0 /minmp ercoupe/Engines/c-75-12.xml: minmp unit=INHG 10.0 /minmp Nordstern/Engines/eng_Maybach_Mb_IVa.xml:minmp unit=INHG 9.0 /minmp SenecaII/Engines/tsio360eb.xml: minmp unit=INHG 10.0 /minmp Short_Empire/Engines/eng_PegasusXc.xml: minmp unit=INHG 10.0 /minmp Submarine_Scout/Engines/eng_RRhawk.xml: minmp unit=INHG 10.0 /minmp ZivkoEdge/Engines/io540.xml: minmp unit=INHG 10.0/minmp ZLT-NT/Engines/engIO360C.xml:minmp unit=INHG 10.0 /minmp -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Flightgear-devel mailing list
Re: [Flightgear-devel] JSBSim Piston Engine Idle
Ron, From experience: the lyco IO540 idles at 14-15 inHG, 900RPM (MT-prop with P-880-xx governor) Eric From: w...@jentronics.com To: flightgear-devel@lists.sourceforge.net Date: Sat, 8 Dec 2012 12:12:23 -0700 CC: jsbsim-de...@lists.sourceforge.net Subject: [Flightgear-devel] JSBSim Piston Engine Idle I took a quick look through the FGData Aircraft directory today and came up with a list of some 27 JSBSim piston engines that still seem to be using either the old aeromatic default values for idle manifold pressure (minmp) or suspiciously low values. As time permits this week I intend to take a deeper look at this list and adjust the minmp value as seems appropriate, if there are no objections. I know a couple of engines have different versions in other repositories (JSBSim or personal hangers) that are updated and just need to be copied into FGData. Ron Probably won't idle: Aerocar/Engines/Lycoming_O-290.xml: minmp unit=INHG 6.0 /minmp an2/Engine/ASH-62IR.xml: minmp unit=INHG 5.0 /minmp Boeing314/Engines/WrightGR-2600.xml: minmp unit=INHG 6.0 /minmp c150/Engines/eng_O-200.xml: minmp unit=INHG 6.0 /minmp c172r/Engines/engIO360C.xml: minmp unit=INHG 6.5 /minmp c182/Engines/engIO540AB1A5.xml: minmp unit=INHG 6.5 /minmp c182rg/Engines/engIO540AB1A5.xml:minmp unit=INHG 6.5 /minmp c310/Engines/engIO470D.xml: minmp unit=INHG 6.5 /minmp c310u3a/Engines/engIO470D.xml: minmp unit=INHG 6.5 /minmp dc2/Engines/R-1820-R52.xml: minmp unit=INHG 6.0 /minmp dc6/Engines/CB17.xml:minmp unit=INHG 6.0 /minmp dc6/Engines/eng_R-2800.xml: minmp unit=INHG 6.5 /minmp Dragonfly/Engines/Rotax582.xml: minmp unit=INHG 2.1 /minmp Dromader/Engine/engine_Asz-62IRM18.xml: minmp unit=INHG 5.0 /minmp fkdr1/Engines/Oberursel-UrII.xml:minmp unit=INHG 6.0 /minmp flash2a/Engines/503.xml: minmp unit=INHG 2.0 /minmp Lockheed1049/Engines/WrightCyclone-975C18CB1.xml: minmp unit=INHG 6.0 /minmp Lockheed1049h/Engines/WrightCyclone-972TC18DA3.xml: minmp unit=INHG 6.0 /minmp Lockheed1049h/Engines/WrightCyclone-975C18CB1.xml: minmp unit=INHG 6.0 /minmp Noratlas/Engines/Bristol-739.xml: minmp unit=INHG6.0 /minmp ogel/Engines/200hp-jsbsim-2.0.xml: minmp unit=INHG6.0 /minmp P-38-Lightning/Engines/Allison.xml: minmp unit=INHG6.0 /minmp p51d/Engines/Packard-V-1650-7.xml: minmp unit=INHG4.0 /minmp PBY-Catalina/Engines/PBY-6_engine-new.xml: minmp unit=INHG 6.0 /minmp Skyranger/Engines/rotax.xml:minmp unit=INHG6.0 /minmp Storch/Engines/Argus_As_10.xml: minmp unit=INHG6.0 /minmp Maybe: G-164/Engines/R-1340-AN1.xml:minmp unit=INHG 7.0 /minmp Good: A6M2/Engines/Sakae-Type12.xml: minmp unit=INHG 10.5 /minmp b29/Engines/eng_R3350.xml: minmp unit=INHG 12.0 /minmp c172p/Engines/eng_io320.xml: minmp unit=INHG 8.3 /minmp C684/Engines/6Pfi.xml: !--minmp unit=INHG 6.0 /minmp-- Cap10B/Engine/LycomingIO360B2F.xml: minmp unit=INHG 12.0 /minmp Cessna337/Engines/engine_IO360C.xml: minmp unit=INHG 15.0 /minmp ercoupe/Engines/c-75-12.xml: minmp unit=INHG 10.0 /minmp Nordstern/Engines/eng_Maybach_Mb_IVa.xml:minmp unit=INHG 9.0 /minmp SenecaII/Engines/tsio360eb.xml: minmp unit=INHG 10.0 /minmp Short_Empire/Engines/eng_PegasusXc.xml: minmp unit=INHG 10.0 /minmp Submarine_Scout/Engines/eng_RRhawk.xml: minmp unit=INHG 10.0 /minmp ZivkoEdge/Engines/io540.xml:minmp unit=INHG 10.0/minmp ZLT-NT/Engines/engIO360C.xml: minmp unit=INHG 10.0 /minmp -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https
Re: [Flightgear-devel] JSBSim Piston Engine Idle
On Tuesday 11 December 2012 00:55:35 Eric van den Berg wrote: Ron, From experience: the lyco IO540 idles at 14-15 inHG, 900RPM (MT-prop with P-880-xx governor) Eric Thanks Eric, The JSBSim piston engine model is missing something, probably Mach effect through the intake valve, so models tend to idle at lower manifold pressures than real engines. The current code idles most engines around 10-11 inHg, but the oldest code used 6 inHg... Ron -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] JSBSim Piston Engine Idle
I see. Looking at the code (I think) I can see you are trying calculate the pressure losses in the injector/throttle valve, airbox and inlet tubes. Using throttle position and engine speed (was expecting cylinder displacement here also). Basically your MAP at idle is to low, thus the pressure loss too high. As 99% of the pressure loss comes from the injector/throttle position, I would say for idle power setting the injector air valve should be a bit more open? I assume it is only calculated for indication and not for engine power calcs? Eric From: w...@jentronics.com To: flightgear-devel@lists.sourceforge.net Date: Tue, 11 Dec 2012 06:20:23 -0700 Subject: Re: [Flightgear-devel] JSBSim Piston Engine Idle On Tuesday 11 December 2012 00:55:35 Eric van den Berg wrote: Ron, From experience: the lyco IO540 idles at 14-15 inHG, 900RPM (MT-prop with P-880-xx governor) Eric Thanks Eric, The JSBSim piston engine model is missing something, probably Mach effect through the intake valve, so models tend to idle at lower manifold pressures than real engines. The current code idles most engines around 10-11 inHg, but the oldest code used 6 inHg... Ron -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] JSBSim Piston Engine Idle
On Tuesday 11 December 2012 09:46:10 Eric van den Berg wrote: I see. Looking at the code (I think) I can see you are trying calculate the pressure losses in the injector/throttle valve, airbox and inlet tubes. Using throttle position and engine speed (was expecting cylinder displacement here also). The displacement is somewhat irrelevant in that it is a constant and can be ignored. The modeler provides two data points; the pressure at full throttle and maximum RPM, and the pressure at 0 throttle and idle RPM. These are used to determine the impedance of the airbox and throttle respectively. In this scheme, the engine is also treated as an impedance which varies with ( 1 / engine speed ) giving infinite impedance at 0 RPM[1] and falling towards, but never reaching, 0 impedance as engine speed increases. We experimented with many other and more complicated intake models early on, and this is the best behaved of the lot. Basically your MAP at idle is to low, thus the pressure loss too high. As 99% of the pressure loss comes from the injector/throttle position, I would say for idle power setting the injector air valve should be a bit more open? I assume it is only calculated for indication and not for engine power calcs? Actually, the manifold pressure is used in three ways in the power calculations. First, it affects the mass flow rate. We assume an adiabatic process so the loss in pressure is accompanied by a corresponding loss of density. Second, the volumetric efficiency is reduced by the intake pressure being less than the exhaust pressure further reducing the mass flow rate. Finally, the pressure difference between intake and exhaust creates a direct power loss as work is performed to pull and maintain the manifold pressure drop. Ron [1] Note: Engine speed actually used is mean pistons speed not RPM. -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] JSBSim Piston Engine Idle
So it is kind of modelled like an air pump. Interesting method. BTW p0 =101325 Pa R = 287.05 Cp_air = 1004.68 gamma = 1.4 Handbook of Aviation fuel properties, third edition: net heat of combustion of AVGAS, all grades : min. 43.5 MJ/kg, 44 typical density of AVGAS: 710 at 15degC C_p_AVGAS = 2.065 kJ/kg K @20degC, approx linear to 2.710 @140degC hope this might improve accuracy (a bit), Cheers, Eric On 12/11/2012 07:35 PM, Ron Jensen wrote: On Tuesday 11 December 2012 09:46:10 Eric van den Berg wrote: I see. Looking at the code (I think) I can see you are trying calculate the pressure losses in the injector/throttle valve, airbox and inlet tubes. Using throttle position and engine speed (was expecting cylinder displacement here also). The displacement is somewhat irrelevant in that it is a constant and can be ignored. The modeler provides two data points; the pressure at full throttle and maximum RPM, and the pressure at 0 throttle and idle RPM. These are used to determine the impedance of the airbox and throttle respectively. In this scheme, the engine is also treated as an impedance which varies with ( 1 / engine speed ) giving infinite impedance at 0 RPM[1] and falling towards, but never reaching, 0 impedance as engine speed increases. We experimented with many other and more complicated intake models early on, and this is the best behaved of the lot. Basically your MAP at idle is to low, thus the pressure loss too high. As 99% of the pressure loss comes from the injector/throttle position, I would say for idle power setting the injector air valve should be a bit more open? I assume it is only calculated for indication and not for engine power calcs? Actually, the manifold pressure is used in three ways in the power calculations. First, it affects the mass flow rate. We assume an adiabatic process so the loss in pressure is accompanied by a corresponding loss of density. Second, the volumetric efficiency is reduced by the intake pressure being less than the exhaust pressure further reducing the mass flow rate. Finally, the pressure difference between intake and exhaust creates a direct power loss as work is performed to pull and maintain the manifold pressure drop. Ron [1] Note: Engine speed actually used is mean pistons speed not RPM. -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] JSBSim Piston Engine Idle
On Tuesday 11 December 2012 13:49:51 Eric van den Berg wrote: So it is kind of modelled like an air pump. Interesting method. Piston engines are basically air pumps. We currently calculate power by dividing the mass fuel flow by the user-entered bsfc multiply by correction factors for mixture and spark and subtract a little bit for good measure. The little bit ensures the engine stops spinning if it isn't producing power. The propeller code will keep it spinning under certain conditions, and needs to be fixed up to let it start the engine spinning again... If I were to start over with this model the biggest thing I would change would be replacing the power calculation with the Otto cycle[note 2] pressure calculations. We already (as mentioned) calculate the area of [1:2]+[6:1] as pumping losses.[note 3] The trick to this method is calculating the [3:4] pressure rise to get the area of [3:4:5:6] This should let us roll the egt and cylinder temp calculations into the power loop and make them more meaningful. Right now they are largely just indications, altough egt does indicate power somewhat correctly. That may be done in the future as we can then more easily add a diesel cycle. Ron [2] http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/otto.html#c5 [3] http://mae.wvu.edu/~smirnov/mae320/figs/F9-2.jpg BTW p0 =101325 Pa R = 287.05 Cp_air = 1004.68 gamma = 1.4 Handbook of Aviation fuel properties, third edition: net heat of combustion of AVGAS, all grades : min. 43.5 MJ/kg, 44 typical density of AVGAS: 710 at 15degC C_p_AVGAS = 2.065 kJ/kg K @20degC, approx linear to 2.710 @140degC hope this might improve accuracy (a bit), Cheers, Eric On 12/11/2012 07:35 PM, Ron Jensen wrote: On Tuesday 11 December 2012 09:46:10 Eric van den Berg wrote: I see. Looking at the code (I think) I can see you are trying calculate the pressure losses in the injector/throttle valve, airbox and inlet tubes. Using throttle position and engine speed (was expecting cylinder displacement here also). The displacement is somewhat irrelevant in that it is a constant and can be ignored. The modeler provides two data points; the pressure at full throttle and maximum RPM, and the pressure at 0 throttle and idle RPM. These are used to determine the impedance of the airbox and throttle respectively. In this scheme, the engine is also treated as an impedance which varies with ( 1 / engine speed ) giving infinite impedance at 0 RPM[1] and falling towards, but never reaching, 0 impedance as engine speed increases. We experimented with many other and more complicated intake models early on, and this is the best behaved of the lot. Basically your MAP at idle is to low, thus the pressure loss too high. As 99% of the pressure loss comes from the injector/throttle position, I would say for idle power setting the injector air valve should be a bit more open? I assume it is only calculated for indication and not for engine power calcs? Actually, the manifold pressure is used in three ways in the power calculations. First, it affects the mass flow rate. We assume an adiabatic process so the loss in pressure is accompanied by a corresponding loss of density. Second, the volumetric efficiency is reduced by the intake pressure being less than the exhaust pressure further reducing the mass flow rate. Finally, the pressure difference between intake and exhaust creates a direct power loss as work is performed to pull and maintain the manifold pressure drop. Ron [1] Note: Engine speed actually used is mean pistons speed not RPM. -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] JSBSim Piston Engine Idle
On Tuesday 11 December 2012 13:49:51 Eric van den Berg wrote: So it is kind of modelled like an air pump. Interesting method. Piston engines are basically air pumps. We currently calculate power by dividing the mass fuel flow by the user-entered bsfc multiply by correction factors for mixture and spark and subtract a little bit for good measure. The little bit ensures the engine stops spinning if it isn't producing power. The propeller code will keep it spinning under certain conditions, and needs to be fixed up to let it start the engine spinning again... If I were to start over with this model the biggest thing I would change would be replacing the power calculation with the Otto cycle[note 2] pressure calculations. We already (as mentioned) calculate the area of [1:2]+[6:1] as pumping losses.[note 3] The trick to this method is calculating the [3:4] pressure rise to get the area of [3:4:5:6] This should let us roll the egt and cylinder temp calculations into the power loop and make them more meaningful. Right now they are largely just indications, altough egt does indicate power somewhat correctly. That may be done in the future as we can then more easily add a diesel cycle. Ron [2] http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/otto.html#c5 [3] http://mae.wvu.edu/~smirnov/mae320/figs/F9-2.jpg BTW p0 =101325 Pa R = 287.05 Cp_air = 1004.68 gamma = 1.4 Handbook of Aviation fuel properties, third edition: net heat of combustion of AVGAS, all grades : min. 43.5 MJ/kg, 44 typical density of AVGAS: 710 at 15degC C_p_AVGAS = 2.065 kJ/kg K @20degC, approx linear to 2.710 @140degC hope this might improve accuracy (a bit), Cheers, Eric On 12/11/2012 07:35 PM, Ron Jensen wrote: On Tuesday 11 December 2012 09:46:10 Eric van den Berg wrote: I see. Looking at the code (I think) I can see you are trying calculate the pressure losses in the injector/throttle valve, airbox and inlet tubes. Using throttle position and engine speed (was expecting cylinder displacement here also). The displacement is somewhat irrelevant in that it is a constant and can be ignored. The modeler provides two data points; the pressure at full throttle and maximum RPM, and the pressure at 0 throttle and idle RPM. These are used to determine the impedance of the airbox and throttle respectively. In this scheme, the engine is also treated as an impedance which varies with ( 1 / engine speed ) giving infinite impedance at 0 RPM[1] and falling towards, but never reaching, 0 impedance as engine speed increases. We experimented with many other and more complicated intake models early on, and this is the best behaved of the lot. Basically your MAP at idle is to low, thus the pressure loss too high. As 99% of the pressure loss comes from the injector/throttle position, I would say for idle power setting the injector air valve should be a bit more open? I assume it is only calculated for indication and not for engine power calcs? Actually, the manifold pressure is used in three ways in the power calculations. First, it affects the mass flow rate. We assume an adiabatic process so the loss in pressure is accompanied by a corresponding loss of density. Second, the volumetric efficiency is reduced by the intake pressure being less than the exhaust pressure further reducing the mass flow rate. Finally, the pressure difference between intake and exhaust creates a direct power loss as work is performed to pull and maintain the manifold pressure drop. Ron [1] Note: Engine speed actually used is mean pistons speed not RPM. -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] JSBSim Piston Engine Idle
I'd be grateful for an update of the Dragonfly and the ogeL. The Dragonfly's configuration was a wild guess, and only very vaguely based on real numbers. ogeL's engine is by definition just fantasy ;-) Thanks, Torsten Am 08.12.2012 20:12, schrieb Ron Jensen: I took a quick look through the FGData Aircraft directory today and came up with a list of some 27 JSBSim piston engines that still seem to be using either the old aeromatic default values for idle manifold pressure (minmp) or suspiciously low values. As time permits this week I intend to take a deeper look at this list and adjust the minmp value as seems appropriate, if there are no objections. I know a couple of engines have different versions in other repositories (JSBSim or personal hangers) that are updated and just need to be copied into FGData. Ron Probably won't idle: Aerocar/Engines/Lycoming_O-290.xml: minmp unit=INHG 6.0 /minmp an2/Engine/ASH-62IR.xml: minmp unit=INHG 5.0 /minmp Boeing314/Engines/WrightGR-2600.xml: minmp unit=INHG 6.0 /minmp c150/Engines/eng_O-200.xml: minmp unit=INHG 6.0 /minmp c172r/Engines/engIO360C.xml: minmp unit=INHG 6.5 /minmp c182/Engines/engIO540AB1A5.xml: minmp unit=INHG 6.5 /minmp c182rg/Engines/engIO540AB1A5.xml:minmp unit=INHG 6.5 /minmp c310/Engines/engIO470D.xml: minmp unit=INHG 6.5 /minmp c310u3a/Engines/engIO470D.xml: minmp unit=INHG 6.5 /minmp dc2/Engines/R-1820-R52.xml: minmp unit=INHG 6.0 /minmp dc6/Engines/CB17.xml:minmp unit=INHG 6.0 /minmp dc6/Engines/eng_R-2800.xml: minmp unit=INHG 6.5 /minmp Dragonfly/Engines/Rotax582.xml: minmp unit=INHG 2.1 /minmp Dromader/Engine/engine_Asz-62IRM18.xml: minmp unit=INHG 5.0 /minmp fkdr1/Engines/Oberursel-UrII.xml:minmp unit=INHG 6.0 /minmp flash2a/Engines/503.xml: minmp unit=INHG 2.0 /minmp Lockheed1049/Engines/WrightCyclone-975C18CB1.xml: minmp unit=INHG 6.0 /minmp Lockheed1049h/Engines/WrightCyclone-972TC18DA3.xml: minmp unit=INHG 6.0 /minmp Lockheed1049h/Engines/WrightCyclone-975C18CB1.xml: minmp unit=INHG 6.0 /minmp Noratlas/Engines/Bristol-739.xml: minmp unit=INHG6.0 /minmp ogel/Engines/200hp-jsbsim-2.0.xml: minmp unit=INHG6.0 /minmp P-38-Lightning/Engines/Allison.xml: minmp unit=INHG6.0 /minmp p51d/Engines/Packard-V-1650-7.xml: minmp unit=INHG4.0 /minmp PBY-Catalina/Engines/PBY-6_engine-new.xml: minmp unit=INHG 6.0 /minmp Skyranger/Engines/rotax.xml:minmp unit=INHG6.0 /minmp Storch/Engines/Argus_As_10.xml: minmp unit=INHG6.0 /minmp Maybe: G-164/Engines/R-1340-AN1.xml:minmp unit=INHG 7.0 /minmp Good: A6M2/Engines/Sakae-Type12.xml: minmp unit=INHG 10.5 /minmp b29/Engines/eng_R3350.xml: minmp unit=INHG 12.0 /minmp c172p/Engines/eng_io320.xml: minmp unit=INHG 8.3 /minmp C684/Engines/6Pfi.xml: !--minmp unit=INHG 6.0 /minmp-- Cap10B/Engine/LycomingIO360B2F.xml: minmp unit=INHG 12.0 /minmp Cessna337/Engines/engine_IO360C.xml: minmp unit=INHG 15.0 /minmp ercoupe/Engines/c-75-12.xml: minmp unit=INHG 10.0 /minmp Nordstern/Engines/eng_Maybach_Mb_IVa.xml:minmp unit=INHG 9.0 /minmp SenecaII/Engines/tsio360eb.xml: minmp unit=INHG 10.0 /minmp Short_Empire/Engines/eng_PegasusXc.xml: minmp unit=INHG 10.0 /minmp Submarine_Scout/Engines/eng_RRhawk.xml: minmp unit=INHG 10.0 /minmp ZivkoEdge/Engines/io540.xml:minmp unit=INHG 10.0/minmp ZLT-NT/Engines/engIO360C.xml: minmp unit=INHG 10.0 /minmp -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
[Flightgear-devel] JSBSim Piston Engine Idle
I took a quick look through the FGData Aircraft directory today and came up with a list of some 27 JSBSim piston engines that still seem to be using either the old aeromatic default values for idle manifold pressure (minmp) or suspiciously low values. As time permits this week I intend to take a deeper look at this list and adjust the minmp value as seems appropriate, if there are no objections. I know a couple of engines have different versions in other repositories (JSBSim or personal hangers) that are updated and just need to be copied into FGData. Ron Probably won't idle: Aerocar/Engines/Lycoming_O-290.xml: minmp unit=INHG 6.0 /minmp an2/Engine/ASH-62IR.xml: minmp unit=INHG 5.0 /minmp Boeing314/Engines/WrightGR-2600.xml: minmp unit=INHG 6.0 /minmp c150/Engines/eng_O-200.xml: minmp unit=INHG 6.0 /minmp c172r/Engines/engIO360C.xml: minmp unit=INHG 6.5 /minmp c182/Engines/engIO540AB1A5.xml: minmp unit=INHG 6.5 /minmp c182rg/Engines/engIO540AB1A5.xml:minmp unit=INHG 6.5 /minmp c310/Engines/engIO470D.xml: minmp unit=INHG 6.5 /minmp c310u3a/Engines/engIO470D.xml: minmp unit=INHG 6.5 /minmp dc2/Engines/R-1820-R52.xml: minmp unit=INHG 6.0 /minmp dc6/Engines/CB17.xml:minmp unit=INHG 6.0 /minmp dc6/Engines/eng_R-2800.xml: minmp unit=INHG 6.5 /minmp Dragonfly/Engines/Rotax582.xml: minmp unit=INHG 2.1 /minmp Dromader/Engine/engine_Asz-62IRM18.xml: minmp unit=INHG 5.0 /minmp fkdr1/Engines/Oberursel-UrII.xml:minmp unit=INHG 6.0 /minmp flash2a/Engines/503.xml: minmp unit=INHG 2.0 /minmp Lockheed1049/Engines/WrightCyclone-975C18CB1.xml: minmp unit=INHG 6.0 /minmp Lockheed1049h/Engines/WrightCyclone-972TC18DA3.xml: minmp unit=INHG 6.0 /minmp Lockheed1049h/Engines/WrightCyclone-975C18CB1.xml: minmp unit=INHG 6.0 /minmp Noratlas/Engines/Bristol-739.xml: minmp unit=INHG6.0 /minmp ogel/Engines/200hp-jsbsim-2.0.xml: minmp unit=INHG6.0 /minmp P-38-Lightning/Engines/Allison.xml: minmp unit=INHG6.0 /minmp p51d/Engines/Packard-V-1650-7.xml: minmp unit=INHG4.0 /minmp PBY-Catalina/Engines/PBY-6_engine-new.xml: minmp unit=INHG 6.0 /minmp Skyranger/Engines/rotax.xml:minmp unit=INHG6.0 /minmp Storch/Engines/Argus_As_10.xml: minmp unit=INHG6.0 /minmp Maybe: G-164/Engines/R-1340-AN1.xml:minmp unit=INHG 7.0 /minmp Good: A6M2/Engines/Sakae-Type12.xml: minmp unit=INHG 10.5 /minmp b29/Engines/eng_R3350.xml: minmp unit=INHG 12.0 /minmp c172p/Engines/eng_io320.xml: minmp unit=INHG 8.3 /minmp C684/Engines/6Pfi.xml: !--minmp unit=INHG 6.0 /minmp-- Cap10B/Engine/LycomingIO360B2F.xml: minmp unit=INHG 12.0 /minmp Cessna337/Engines/engine_IO360C.xml: minmp unit=INHG 15.0 /minmp ercoupe/Engines/c-75-12.xml: minmp unit=INHG 10.0 /minmp Nordstern/Engines/eng_Maybach_Mb_IVa.xml:minmp unit=INHG 9.0 /minmp SenecaII/Engines/tsio360eb.xml: minmp unit=INHG 10.0 /minmp Short_Empire/Engines/eng_PegasusXc.xml: minmp unit=INHG 10.0 /minmp Submarine_Scout/Engines/eng_RRhawk.xml: minmp unit=INHG 10.0 /minmp ZivkoEdge/Engines/io540.xml:minmp unit=INHG 10.0/minmp ZLT-NT/Engines/engIO360C.xml: minmp unit=INHG 10.0 /minmp -- LogMeIn Rescue: Anywhere, Anytime Remote support for IT. Free Trial Remotely access PCs and mobile devices and provide instant support Improve your efficiency, and focus on delivering more value-add services Discover what IT Professionals Know. Rescue delivers http://p.sf.net/sfu/logmein_12329d2d ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
