I've always found that even large or heavy aircraft like LD-767 or PMDG-747 move like a Cessna while taxiing or during takeoff roll. I'm referring to excessive rudder sensibility on the ground. I've tried with FS9 calibrations or via FSUIPC, but the result is still very unreal, you have to be very careful to avoid having the plane swinging from side to side of the runway. My question: will changing (decreasing) rudder efectiveness in the flight controls section of the "aircraft.cfg" file be helpful ? Thanks in advance.

In general for take-off try turning off the YAW damper. In FS sensitivity I place a very small bit of null to avoid the center of the hardware pedal range which can be subject to noise and instability. Too much null increases sensitivity and makes (in this case) control sloppy in the center range I believe. This is better calibrated with FSUIPC. In FSUIPC (paid registration) you can map the center sensitivity to be less than the outside of the range. This preserves full nosewheel/rudder deflection when you need it. In addition current versions of FSUIPC offer a 'tiller' function that if you enable it lowers sensitivity below a certain IAS. Remember that FSUIPC can make your mappings global or aircraft dependent. Here's mine: Extract from the FSUIPC 3.99 User Guide searching under 'tiller' ; "One additional axis of note, not available elsewhere, is the Steering Tiller. This uses the FS Rudder control, but can be calibrated separately (eg to be more responsive—use the inverse S-shaped slope options). If the steering tiller axis is assigned, you must then calibrate it in FSUIPC's Joysticks section (this is on the same page as the PAN controls … sorry!). You need to calibrate the rudder axis in FSUIPC too. Then the two are used together as follows:When on the ground and at any ground speed less than 60 knots (default—adjustable by the MaxSteerSpeed parameter in the INI file), the actual FS rudder action is controlled by a blend of the tiller and rudder axis inputs. At low speed it is predominantly tiller, and as speed increases the tiller becomes gradually less effective and the rudder input more so. Above the MaxSteerSpeed, or in the air, the tiller has no effect.As with all of the axis and joystick facilities, the calibrations, assignments and parameters such as MaxSteerSpeed, can be different for different aircraft." It takes a little work but might solve your problem.

Get a registration for FSUIPC then you can access the advanced assignment and calibration tools. One of the most useful is the ability to put a "slope" on any axis. The rudder benefits greatly from this... as you move your rudder hardware the output is progressive so the first half of travel results in gentle movement of the rudder, yet you still get full travel if you push the rudder hard over.

Thanks for your help. Yes, I have a registered copy of FSUIPC, but still the result with rudder control is not satisfactory. as I said, I'm testing the effect of changing the rudder effectiveness value in the aircraft.cfg file of the IFLY-737 and LD-767. I will post the results.

Ok, I modified the aircraft.cfg file for the IFLY 737-800 in the [flight tuning] section: rudder_effectiveness = 0.50 // it was 1.00elevator_effectiveness = 0.70 // it was 1.00 No FSUIPC calibration.FS9 Joystick sensibilities about 25% (except throttle 100%) with a small null zone. From being a jerky aircraft, now it behaves like a charm and hand flying it is a total delight, having the stable and soft movements that (I presume) an airliner should.

Ok, I modified the aircraft.cfg file for the IFLY 737-800 in the [flight tuning] section: rudder_effectiveness = 0.50 // it was 1.00elevator_effectiveness = 0.70 // it was 1.00 No FSUIPC calibration.FS9 Joystick sensibilities about 25% (except throttle 100%) with a small null zone. From being a jerky aircraft, now it behaves like a charm and hand flying it is a total delight, having the stable and soft movements that (I presume) an airliner should.

This may seriously limit rudder's and elevator's authority, may affect aircraft's performance in some situations. Whereas the previous example with FSUIPC calibration will keep their limits uncut. Dirk.

I´ll make a complete flight from LEVX to LEMD (about 300 nm) in the next days and will tell you about it.I can only say that the sensations and the aircraft behaviour were totally new for me and of course extremely good. ( I was, in fact, about to keep the Ifly 737 in his hangar and go back to the PMDG one).

Jose Luis, In your first post you talk about "rudder" sensitivity issues "on the ground". By this I assume you are in fact talking about nose wheel steering sensitivity which is independent of any rudder sensitivity during flight. If so, this should or may be changed in the aircraft's aircraft.cfg file. Go to the [Contact_points] section. The first line "point.0=" contains the nose wheel properties. After he 7th comma "," (the 8th value) you will find the maximum nose wheel steering angle in degrees. This value can be anywhere between 30.000 and 60.000 degrees. Change this value to e.g. 25.000 and try your plane's reactions. However, after decreasing this value it may become necessary to use toe brakes to make sharp turns. In some of the heavier planes with dual nose wheels you could see a second "point.1=" entry which contains the same 8th value as in "point.0=". This must then also be changed so that both are the same. Good luck. Hans

Thanks for your great information Hans. Well, I use a Thrustmaster joystick with a twisting handle, and there must be some connection between the rudder and the front wheels in FS9 while on the ground because they move simultaneously when I turn the handle. I'll try what you said in your post.

Further up I read "In general for take-off try turning off the YAW damper."The yaw damper MUST be ON! Within the sim it has little effect one has to say. However, in real aviation it must be ON.vololiberista

Not in all circumstances. First, in the sim, the nosewheel is coupled to the rudder, not independent. Yaw damper does reduce rudder sensitivity. r/w the yaw damper counters the sensitivity in the AP yaw axis so servo 'junting' is reduced. The symptom of hunting is Dutch roll, which is basically tail wag. This is an oscillation where the AP is correcting heading but goes slightly past the correct point, reverses the correction, and then the whole business starts again. Some aircraft do have the YD on and some do not initially during take-off. It is turned on as you get to cruise climb in these where turns are less critical outside of the immediate departure area. For this discussion perhaps with it on nose wheel control in the sim could be sloppy.

Further up I read "In general for take-off try turning off the YAW damper."The yaw damper MUST be ON! Within the sim it has little effect one has to say. However, in real aviation it must be ON.vololiberista