Correction of strange yaw behaviour

[DescendDescend 25]

I would appreciate some advice as an airfile amateur.I have noticed one or two aircraft seem to yaw around their center of mass while the mass tends to continue in a straight line. This is particularly obvious on approach (and probably due in part to my poor technique)when I want to steer back to the localiser - the nose will point in the direction I require but the mass carries on.Any advice on which table(s) should be adjusted to reduce that tendency?Many thanksHoward

[Guest Milton]

Take a look at table 1101 in the .air file, Yaw and Side Force sections, particularly sideslip in each.

[DescendDescend 25]

Thanks,Huge improvement,

[Guest Tom Goodrick]

You did not mention whether you observed this in a wind. If there was no wind, then you observed the fact that some aircraft can operate with a substantial sideslip. I often use a sideslip gauge I wrote in xml. It shows many aircraft in FS can fly with a 15 degree sideslip if you hold full rudder. This does indeed mean the aircraft is looking one way and flying another. This angle is a bit unrealistic. About 5 degrees would be more realistic unless it is a twin engine aircraft. In twins, the rudder is powerful to offset the yaw that comes from losing an engine. You can always decrease the rudder power using the tuning section in the aircraft.cfg file if you feel an aircraft has too much rudder power.If there was wind involved in your approach, the motion you see is quite normal. With a wind from the left, if you point the nose at the runway, you will see a drift to the right as you progress. You would counter this by simply turning to head into the wind. You would turn so the nose pointed left of the centerline and keep the motion of the aircraft in line with the centerline. Then when over the runway, you move the nose right with the rudder and dip the left wing down a bit to continue tracking straight down the runway. That's how you do it in real life. In FS you can simply land in the 'crab' (facing left) because FS has very little lateral wheel friction.Some planes I have downloaded have such poor directional stability that they just yaw back and forth as they fly. If you get one of these, check Cn_beta in section 1100 of the .air file and increase it a bit.

[DescendDescend 25]

Hello Tom,I have been reading and digesting an interesting document called Flight Dynamics For Microsoft Flight Simulator. You may be familiar with it.:-)Regarding the original post the aircraft in question is an A340. It appears that if I drift off the localiser due to a 5 knot cross wind the later I leave correction the more prominent the problem becomes until it is impossible to make the required correction.The other issue is that it seems to be impossible maintain a reasonable approach attitude through the full weight range with full flaps. I get a pitch of +3 degrees at max lw and -1 min lw using the fs autoland. I guess manual trim is the only solution.Your thoughts appreciated.Regards.

[DescendDescend 25]

Hello Tom,I have been reading and digesting an interesting document called Flight Dynamics For Microsoft Flight Simulator. You may be familiar with it.:-)Regarding the original post the aircraft in question is an A340. It appears that if I drift off the localiser due to a 5 knot cross wind the later I leave correction the more prominent the problem becomes until it is impossible to make the required correction.The other issue is that it seems to be impossible maintain a reasonable approach attitude through the full weight range with full flaps. I get a pitch of +3 degrees at max lw and -1 min lw using the fs autoland. I guess manual trim is the only solution.Your thoughts appreciated.Regards.