On Thursday 19 January 2006 23:59, Steve Knoblock wrote: > I have been digging into the NASAL electrical system code > (supplied with the C172---I cannot speak for any other > aircraft that runs a modified system). I have always > appreciated when a flight sim models behavior of the battery > in a realistic manner as is reasonable. Looking at the code, I > noticed a comment that Cold Cranking Amps might be a feature > to incorporate in the future. I was prompted to do a little > research and see if this was reasonable and what approaches > might be made to improving the battery model. > > The main areas I see ready for improvement are: > > > * Cold Cranking Amps: An aircraft should fail to start in very > cold weather when CCA is affected by temperature, or when > insufficient CCA is available for any reason. > > * Deep Discharge (or Cycling): Should the battery be allowed > to discharge completely, it should fail (i.e. no longer > provide energy or sufficient energy to start until the sim is > reset). > > * Battery Response to Temperature: The output of a battery > degrades as temperature drops in a fairly predictable manner > (at least for a "generic" battery...it would be unreasonable > to turn FG into a battery simulator and the data for an > individual battery is very difficult to come by even for > industrial uses). > [snip...] > > References > ============================================================== >========================== > > http://focus.ti.com/general/docs/lit/getliterature.tsp?baseLit >eratureNumber=slyp086&fileType=pdf > http://en.wikipedia.org/wiki/Car_batteries > http://mtrl1.me.psu.edu/Simulation/Description.htm > http://www.batteryfaq.org/ > http://www.uuhome.de/william.darden//carfaq7.htm#cca > http://windturbine.ca/batteries.html > http://www.batterystuff.com/tutorial_battery.html > http://www.uuhome.de/william.darden//carfaq7.htm > > > > I believe all these features are achievable with reasonable > level of fidelity. I doubt my ability to code these on my own, > so feel free to make what you will of the research and make > suggestions. > > Steve
Hmm... this made me think about how some aspects of realism and accuracy may not always be a good idea. For example, if the temperature is so low that CCA is inadequate to start the engine what is the solution? In real life I guess you wouldn't be able to fly but a flight simulator that refused to let you get in to the air wouldn't be very useful. That's not to say that an accurate/realistic battery model isn't a good idea but you might have to assume that all aircraft have been stored in a heated hanger before they're pulled out for a flight. LeeE ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=103432&bid=230486&dat=121642 _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
