79:: Let’s do an ordinary preflight runup in the c182rg. With the prop control full forward, advance the throttle to 1700 rpm in accordance with the POH checklist. Now pull the prop control full back. In the Sim World as of 1.9.0, I observe the RPM drops from 1700 to 1400. This is highly unrealistic, because in the Real World, the drop is much greater; I estimate the low RPM is down around 900 or so.
As a related observation, with the SW throttle all the way back, the property tree says that the governor is regulating the propeller at 900 rpm. That is, the propeller pitch is not on the fine-pitch stop, even with the throttle all the way back, with the engine developing only 10% of its rated shaft horsepower. This is highly unrealistic. As previously mentioned, 900 RPM is about the right number, but the prop really should be on the fine-pitch stop. Advancing the throttle a tiny bit above idle causes the prop to hit the coarse-pitch stop. This suggests there is something wrong with the propeller model. There is no chance that this problem is related to bug 80. The propeller is misbehaving as a function of shaft power, and if you know the shaft power, it doesn’t matter what throttle setting or other settings produced that power. 80:: As of 1.9.0, in the c182rg on the runway at KSFO, I observe that with the throttle wide open the MAP is 29.97. With the throttle pulled back to 0.6, the MAP is still 29.97. This is wildly unrealistic. Similar problems in the c172p model have been reported. In the Real World, the throttle is a butterfly valve; flowing a large amount of air through a half-closed butterfly valve causes a large pressure drop. Any RW pilot would notice this before takeoff, and would conclude that the throttle (or throttle linkage) was broken. This problem almost certainly results from an unphysical model embodied in the .cxx code. The code does not model the throttle as a valve. As a consequence, no amount of fiddling with the engine configuration .xml files will fix this problem. There is no chance that this problem is related to bug 79. 81:: Consider the case where FlightGear is run with the --disable-ai-models command line option. It appears that some of the ai-related code continues to run. You can easily verify by turning on log-level=info, in which case you will see screen after screen of “scheduling” messages. The messages refer to “scheduling” events many days in the future. I reckon they shouldn't be scheduled at all when the ai-models feature is turned off. For additional details, see http://www.av8n.com/fly/fgfs/htm/bug-list.htm#bug-ai-scheduling ------------------------------------------------------------------------------ Check out the new SourceForge.net Marketplace. It is the best place to buy or sell services for just about anything Open Source. http://p.sf.net/sfu/Xq1LFB _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
