Guys,What deos these value mean in the aicraft.cfg file under the flight tuning section?The original value are 1.0. What are the effect of changing 1.0 to higher value o lower value?I hope yo guys could advise me as I'm trying to tune my landing problem in my B737-400.Thank you in advance for your kind attention and help!

There are two main effects:1: To alter the rate at which the trim functions. This is an `apparent` effect rather than real, because trim effectiveness increase does not equal an increase in movement or speed of the virtual trim surface. So a single keypress will result in more trim adjustment per press. Depending on what kind of system, what kind of controller you have and what aircraft you are flying you might want to adjust this figure to make getting a correct trim a bit easier by making trim response sharper or blunter.2: Trim effectiveness aso relates to the autopilot. In FS, the a/p controls the attitude of the aircraft through the trim function, not by direct control of the flying surface. Making the effectiveness numbers bigger or smaller means the autopilot will respond faster to changes in attitude command.Hope this helps.Allcott

Interesting explanation.Microsoft states in their FS2002 Aircraft Container SDK that these parameters are multipliers of the default power of the trim control surfaces.The default value is 1.0, and each increase of 0.1 to these parameters will increase the effectiveness of the related control surface by 10%. Hence, a value of 1.1 is equal to 110% of the default control surface power.So the 1.5 that Kevin has entered for elevator and aileron trim means a 50% increase over the default trim control surface power.MS further states that if you enter a negative number for these entries it will reverse the effect of the control (it's hard to understand how that would be desirable), and that if you delete the entry altogether then FS will revert to the default value of 1.0.The elevator trim is used by the autopilot pitch axis. However, the ailerons, not the aileron trim, control the roll axis. If you set the trim limits for aileron and rudder to zero in either the aircraft.cfg file or in the airfile Rec 516 it will have no effect on autopilot operation.Setting a rudder angle limit of zero in the aircraft.cfg file or in Rec 320 in the airfile also has no effect on autopilot operation, the aircraft will turn as before, and the sideslip angle during the turn will remain the same. This is true for FS2002 and for FS9, the only difference between the two versions is that if you assign a value of zero to the rudder angle limit in the aircraft.cfg file in FS9 aircraft it results in the aircraft tumbling out of control. This seems unrelated to autopilot operation, as it occurs even when the autopilot is not in use. So it looks to me like the MSFS autopilot in either version of Flight Simulator does not control the yaw axis at all, meaning it is not a true three-axis autopilot.Regarding the aileron and rudder trim, most airfiles have these parameters set too high; they should be lowered (preferably in the airfile) to a more useable effectiveness. Airfile Rec 516 settings of about -0.05 for aileron trim, and 0.05 for rudder trim work well for most aircraft.Or you can lower the trim effectiveness scalars in the aircraft.cfg until you're satisfied with the result. You can find more information on MSFS flight dynamics and free utilities for editing airfiles here:http://perso.wanadoo.fr/hsors/FS_Soft/index.htmlAlso, you can ask any questions you have about correcting the landing problem in your 737 here:http://www.avhistory.org/scripts/MegaBBS/f...w.asp?forumid=5and you will most likely receive a helpful reply from a knowledgeable person.

Hi Douglas,Thank you so much for your reply, I really appreciate it very much!I will study the aircraft.cfg and try to fune tune to correct the only problem I have in fs9 at the moment... that's is my B737-400 always pitch up violently and lost control when I disengaged the AT and APPR mode 200-300ft above runway threshold with full flap and speed of 145 kias for landing! (145 kias FOR landing seems too fast to me but I was advised by other simmers that to correct my prblem, my speed should be at least 135-150 kias to avoid to pitch-up problem)In fs2002, with even speeed at 115 kias/full flap, the fs2002's b737-400 just land perfectly!Tanks again Douglas!