Aircraft parameters

[robert41]

Hello. I am searching for the CFG and, or AIR file parameters that make an aircraft wing self center. That is, when banking, then centering the flight stick or yoke, some aircraft wings will return to level, other aircraft will remain banked. Any help would be great.

[warchild]

theres two main places that can be changed that will adjust whether a plane returns to center or not. The easiest for the majority of people is to go into the aircraft.cfg file and under the flight tuning section, adjust the roll stability upward to decrease the tendency to roll back and downward to increase it.

The second is a bit more complex.

in the air file, under table 1101, you have the ROLL subsection, and aat the top of that subsection is "dihedral effect". Increasing that number will increase the aircrafts tendency to roll back to level, and decreasing it will decrease that tendency. However, You have to keep in mind that the airfile is not simply a database for numbers. its a relational table. When you change the dihedral, it can easily have an effect on the yaw settings ( also in table 1101 ), so give it a try with dihedral, and if your yaw goes out of whack, you will need to experiment to correct the problem..
Pam

[Brett_Henderson]

Also.. check the aircraft.cgf file entries representing the vertical position for empy-CoG & wing apex.

Aside from dihedral, the tendency for an aircraft to return to wing-level flight, is the "pendulum" effect. The default C172 for example, does not return to level, like it should, because the CoG and wing apex, in the cfg, are the same, vertically... when in reality, the CoG is "under" the wing-apex. typical of "high wing" aircraft.

Here are the default C172, vertical entries (in red).. you can see they're both zero.. where the wing-apex should be more than a foot higher than the CoG.


empty_weight_CG_position = -3.0, 0, 0 // (feet) longitudinal, lateral, vertical distance from specified datum


[airplane_geometry]
wing_area = 174.0 //Square feet
wing_span = 36.1 //Feet
wing_root_chord = 4.9 //Feet
wing_dihedral = 1.7 //Degrees
wing_incidence = 1.5 //Degrees
wing_twist = -3.0 //Degrees
oswald_efficiency_factor= 0.68 //Measure of lift effeciency of wing
wing_winglets_flag = 0 //Are winglets available?
wing_sweep = 0 //Degrees, wing leading edge
wing_pos_apex_lon = -2.4 //Feet, longitudinal distance from reference point, negative going aft
wing_pos_apex_vert = 0.0 //Feet, vertical distance from reference point, positive going up

Compounding this, is that the wing tanks ARE "above" the CoG, as they should be, but probaly too far above.



[fuel]
LeftMain = -3.9, -2.1, 2.5, 26.5, 0.0 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)
RightMain = -3.9, 2.1, 2.5, 26.5, 0.0 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)


I resolved this in my FS9 installation, years ago, but haven't flown the C172 much in FSX, and can't remember the exact numbers I used. And of course every airplane is different, ala, +/- a foot won't matter much on a 747, but will make a big difference in a C172.

[robert41]

Thanks for the replies everyone. This gives me something to look at and try.

[HighGround22]

. . . go into the aircraft.cfg file and under the flight tuning section, adjust the roll stability upward to decrease the tendency to roll back and downward to increase it. . . .

For quite a while now, I've wondered which way that worked. I'd think, "Okay, run the number down and make it less "stable", so it'll level-off better -- or should I run the number UP to make it MORE stable? And of course I'd drive myself a bit woo-woo.

So thanks for clearing that up, Pam!

[warchild]

if your looking to make the plane roll back to center on its own, you want it less stable, but if your looking for smoother banks with less muscle behind the control, you want it more stable. The Flight tuning parameters are trade offs as they invisible effect several parameters in the air file, but its a quick and dirty way of accomplishing your goal..