On Saturday 15 April 2006 03:55, Dave Culp wrote: > > The 737-300 uses a CFM56-3 engine and the stabilized idle EGT should be > > approximately 475 degrees Celcius although it can be as high as 650 > > degrees Celcius on a hot day in bleed configuration and if it's in a bad > > condition. > > My manual says 360 to 510 degrees.
I suppose it depends on the engine variant being used. I'm using the CFM56-3C-1 data from the Boeing 737-300,400,500 operations manual which was last revised in December 2002 and from CFM's web site. ( http://www.cfm56.com/engines/cfm56-3/tech.html ) Maybe that figure is for the 3-B1 or 3B-2 variant. > The turbine model has no way of knowing what a particular engine will > display for EGT. It depends not only on the engine's thermodynamics, but > also the EGT probe placement. I intended for users to add "offsets and > scales" in the instrumentation code to bring the EGT in line with > expectations. In fact, I at first considered just reporting EGT as a > normalized value, since any value it provides will be wrong anyway. Yes, I suppose it's not something that can be generically modeled easily. Maybe it really should be modeled in nasal and left out of the engine modeling all together since it'll be impossible to model correctly for all engine types. There was one other thing I saw - the EGT falls off too fast when shutting down the engine. It drops from 378 degrees C down to ambient temperature in less than 1 minute and cools down at a linear rate. I'm sure there would be lots of happy pilots if it did that in real life. Hot restarts would be a thing of the past. :) > > Also the N1 and N2 seem to hit a brick wall when they reach their maximum > > and minimum. Instead of slowing down as they reach their limits they > > suddenly stop at the limits. > > The brick wall is a feature. Looks right to me. Hmmm ... I always thought that the engine acclerations would slow down a bit as they reach their limits. This is at least what I've seen from cockpit videos. The last few percent near max RPM should take a few seconds to reach. If it doesn't battle to reach the upper limit doesn't it mean that there is no RPM limit and the engine should be able to rev to infinity? Maybe some RW airline pilots could give their input on this? (Do we have any such lurkers on the lists?) > For some reason I always find myself a bit unenthusiastic about attending > to your complaints. I wonder what the reason could be? I guess I forgot to coat it with honey and icing sugar. :) Sorry, l guess my linguistics and inter-personal relationship skills suck. I know I faired below average in that area the last time I took an aptitude test. I didn't mean it as a personal attack on your work. Paul ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
