Crosswind Rudder Trim

[Guest Overhyped]

Morning guys!Yesterday I tried my first crosswind approach in the 737-600. I let the autopilot take the bird down to 1500' and then decided to hand fly her in from there. Upon landing I got a severe swerve to the right (into the crosswind). This right-hand turning tendency continued all the way down to taxi speed. I am assuming that this is because the autopilot applied rudder trim to counteract the crosswind during approach. My questions are a) is this the right interpretation of what happened, or was it just my shoddy landing, and :( how can I see the rudder trim from in the cockpit, i.e. is there a rudder trim guage?Many thanks in anticipation of some quality replies!Paul Mallows...PS: Tim's tutorials are much looked forward to! They have helped me enjoy this aircraft and simming in general immeasurably, so thank you if you are reading this!

[marcom 139]

Hi Paul,THe 737NG's autopilot CAN NOT move the rudder. Not in autoland nor during normal operation. Also, note, you never use the rudder on modern jet aircraft EXCEPT during engine failure or during crosswind landings in the last 20 feet (but not before).EDIT: there is another occasion where you use the rudder pedals: if you encounter serious loss of control, you can use the rudder to help roll the aircraft back into a normal situation. (For example a severe shear that rolls the aircraft inverted or a bank angle in excess of 70

[Guest Darren Howie]

Hi PaulOk here we go.The reason the aircraft attempts to yaw into the wind is simply caused by the crosswind itself and has nothing to do with rudder trim.The correct technique to use in crosswind conditions is fairly standard.Ensure when you touchdown the aircraft is aligned with the runway.This can be done by a crabbing technique app or by the preferred technique of straightening the aircraft just prior to touchdown with rudder.This is a good technique as when you touchdown the rudder is already in the correct position to help counteract the effect of the crosswind.Ok having landed lower the nosewheel onto the ground promptly.Use nosewheel steering to maintain directional control.Use rudder to assist in directional control by pushing rudder in the opposite direction to the direction that the aircraft attempts to yaw.IE into the wind.Apply aileron in the direction the wind is coming from.IE if the wind is from your left side place the controls to the left also to assist.Apply moderate braking for both braking action and additional nosewheel authority.You can see in a real aircraft it is a real juggling act and as we say a crosswind landing is never over until you have turned off the runway.Have fun and remember practise makes perfect.Lots of practice makes more perfect!!EnjoyDarren Howie

[Guest jcomm]

This sort of situation, where uncrabing results in sideslip towards upwind (in the direction from where the wind is blowing...) has been raised here several times.Suposedly, patch 1.3 solved it. At least I have tried it a few times, even at extreme crosswind components, and it now works correctly.In real life the type of aircraft modelled here will start drifting downwind (for instance, if wind is blowing from the left, it will drift to the right...) as soon as the pilot uncrabs to align with the rw heading. The wind pushes the aircraft, and that is why as you uncrab you also use upwind aileron to lower the upwind wing a little bit (must be done with caution because there is risk of the engine nacelles hiting the rw!!!).On many MSFS aircraft (add-on), there is a wrong effect when an aircraft is uncrabed, making it move "towards" the wind instead of "with" the wind... I think PMDG has changed a few critical parameters on their AIR files and it now feels a LOT better.Single engine performance is still way too "soft". ALthough real 737NG drivers say the aircraft is easily handled on such situations, rudder and rudder trim is really needed (in considerable amount, varying with the situation...) as opposed to the almost unnoticeable effect on PMDG's 737s...On the RUDDER TRIM side of the question, I should point out that although there is no gaugue showing it, you can in fact assign keyboard keys to rudder trim inputs, and it will help under such situations... YET!!! rudder trim SHOULD NEVER BE USED for crosswind landings!!!

[SQUAWKIDENT 3]

>THe 737NG's autopilot CAN NOT move the rudder. Not in autoland>nor during normal operation. Also, note, you never use the>rudder on modern jet aircraft EXCEPT during engine failure or>during crosswind landings in the last 20 feet (but not>before).Should add that YOU SHOULD ALWAYS use rudder to balance turns when hand-flying any aircraft (from gliders to big jets). Obviously in the PMDG 737 you don't need to do this when the aircraft is flying on AP but should always keep the aircraft in balance during manual inputs.RegardsAdam Moore

[marcom 139]

"Should add that YOU SHOULD ALWAYS use rudder to balance turns when hand-flying any aircraft (from gliders to big jets)"No No No!Do you actually fly any aircraft??Yes, when flying gliders and G/A aircraft, you gotta usa the rudder for coordinated turns. Did you ever see a bonanza? There you have springs which move the rudder when you turn the yoke. Not 100% in all situations, but good enough during cruise.Now, on big aircraft, you have a system called a yaw damper. This (besides other things) will make you fly coordinated turns and you never have to touch the rudder pedals during turns. The yaw damper will add rudder according to the situation. FS2004 doesn't handle this system - it only models a very basic and inaccurate YD.PS this has nothing to do with the autopilot.The yaw damper is always on during normal operations, and needs electricity, IR input and hydraulics to operate.Regards,Mark

[Guest tmetzinger]

one other potential culprit - as others have noted, it's possible to get your throttles "unsynced". If you do this by accidentally hitting the E key, when you disconnect your autothrottles you'll end up with a thrust imablance, which will cause your aircraft to yaw.So, in addition to everything else mentioned - look at your engine gauges and make sure they are in sync.

[Guest BrunoF]

Mark is correct. That's why you have to turn the Yaw Damper switch OFF when you would like to manually input some pressure on the rudder pedals.Bruno Francescoli.

[Guest Iz]

On smaller aircraft up to fairly sized turboprops, yes, but on large jets, you always leave the YD on and you can still give control the rudder very well manually.

[Guest BrunoF]

Forgot to add that "little" detail ... heheThanks Iz!Bruno Francescoli.

[SQUAWKIDENT 3]

"No No No!Do you actually fly any aircraft??"I have held a UK PPL/IR/NR since 1983 if that helps.I should have added that bit about the Yaw Damper but my own aircraft does not have one (DR400)and I have no interest in flying big jets (only virtual ones:-)RegardsAdam Moore

[marcom 139]

Hi Adam,"I have held a UK PPL/IR/NR since 1983 if that helps."Ok, I just thought you didn't have any experience due to this phrase:"Should add that YOU SHOULD ALWAYS use rudder to balance turns when hand-flying any aircraft (from gliders to big jets"Anyway, what a NR? Night rating?Regards,Mark

[SQUAWKIDENT 3]

Yes Night Rating. Not sure what the "euro" JAR equivalent is now I am sure someone could tell me;-)So if the Yaw Damper isn't modelled in FS2004 surely one should continue to use the rudder to balance turns? Whenever I fly the PMDG737 the "slip ball" goes out during turns with Yaw Damper ON so I coordinate the turn (as in a real aircraft) with rudder. That's how I was taught 21 years ago (sounding old now..)CheersAdam Moore