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Crab Angle/Wing Low crosswind landngs (Read 1208 times)
Dec 11th, 2009 at 10:52pm

snippyfsxer   Offline
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It there is one thing that I just suck completely at it is crosswind landings.  Or at least I think I do;  In a moderate crosswind in a GA aircraft I always seem to come down a couple of feet to either side of the center line.  I don't have a feel for how to evaluate my performance since it is just me at the computer.
So I ask about technique.  If I'm approaching at a crab, do I then transition to a wing low (let us use a C182), and when?  Do some of you r/w guys wait until the last minute and kick the crab angle out?  I know there are various techniques, but I just can't seem to adopt the right one.  In a heavy crosswind, are you guys more apt to "plant" the airplane, as discussed in another thread?  Because my drift across the center line always occurs after I have flared and am waiting for the plane to settle.  I know there must be a better way to do it than I'm doing it.
 
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Reply #1 - Dec 11th, 2009 at 11:09pm

Mobius   Offline
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On a crosswind landing, you're going to touch down in line with the runway and with a wing low.  On your approach, you're going to be crabbed into the wind so you track the runway heading.  I wait until I cross the end of the runway, just before the round-out and flare to get the crab in and the wing down.  As an example, lets say the wind is from the left.  You will approach the runway with the nose pointed to the left of the runway enough to fly down the extended centerline.  As you get close to the flare, you'll want to point the nose of the airplane down the runway centerline using the rudder.  Since doing that will cause you to drift to the right, you'll have to roll to the left to stop moving relative to the runway and you'll want to hold the rudder and aileron in until you touch down.  Flare with the elevator like you normally do.  Since your touching down rolled to the left slightly, you'll touch down with the left wheel first, then the right wheel, and finally the nose wheel.  As the airplane settles on the runway, you'll want to slowly ease the rudder out so you don't touch the nosewheel down and go shooting off the side of the runway and you'll also want to slowly roll the aileron all the way to the left so any gusts don't flip the aircraft over as you're slowing down.  That should be about it.  Landing with a crosswind in FS is a bit tricky, but it can be done.
 

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Reply #2 - Dec 11th, 2009 at 11:18pm

snippyfsxer   Offline
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Ok, so for you Mobius, the kicking out of the crab part and wing low are really part of the same technique?  I was under the impression that some people actually adopt a wing-low some ways out and basically fly the aircraft in a sideslip for quite a while.  I guess I better get practicing! Is there a particular reason why landing FS in a crosswind is trickier than in real life?
 
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Reply #3 - Dec 12th, 2009 at 1:21am

beaky   Offline
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snippyfsxer wrote on Dec 11th, 2009 at 11:18pm:
Ok, so for you Mobius, the kicking out of the crab part and wing low are really part of the same technique?  I was under the impression that some people actually adopt a wing-low some ways out and basically fly the aircraft in a sideslip for quite a while.  I guess I better get practicing! Is there a particular reason why landing FS in a crosswind is trickier than in real life?


This idea of "kicking out" something creates a mental stumbling-block...
In a crab, you are wings-level and rudder centered. It's coordinated level flight at an angle that allows you to track the centerline despite the wind. Transitioning to what is effectively a sideslip does require applying a little rudder and lowering the upwind wing somewhat, but you're not kicking anything. All you're doing is using aileron for directional control and using rudder to align the nose the way you want it relative to your path, just as you would in any mode of flight. The amount of aileron and rudder may be very slight, also, but as Mobius points out, if you don't lower one wing slightly you are going to drift downwind (relative to the centerline). And you want to have the nose aligned with the runway as much as possible.
You can also sideslip all the way down on final... neither method is more likely or unlikely to succeed, and it's mostly a matter of preference. Some people don't like to have to hold uncoordinated inputs (rudder deflecting opposite the ailerons) for such a long period, others don't like to transition from a crab to a sideslip at the last moment. The bottom line, though, is that you will have to touch down in a sideslip, whatever amount is needed so that the drifting effect of the wind is negated by the airplane's sideways motion into the wind. And you'd better have the nose aligned with the runway, or at least with your actual path through the air... some airplanes are more tolerant of this than others, but the goal is to not side-load the mains if you can help it, or to veer off the edge of the runway as soon as all wheels are down.

I can't explain why most MSFS models are harder to land in x-winds than in real life; clearly the flight dynamics are not quite there even with the best models. It's similar to how most FS models will weathervane  (try to point into the wind) even in flight, if the winds aloft change direction. This is not quite what happens in real life, and they certainly don't weathervane on the runway in light winds the way they do in FS! they certainly will weathervane, some more than others, but a Cessna 172 for example, with all 3 wheels on the ground, is not going to be difficult to steer down the centerline because of wind. The nosewheel's friction and the fact that the CG is forward of the mains helps a great deal with that... in real life. Grin

But of course there are reasonable limits, in real life as in sim flying... sometimes you just cannot bank enough to stop the drift, and/or use enough opposite rudder to keep going straight as you touch down. And sometimes you just cannot safely roll out or taxi in a crosswind. It depends, ultimately, on the velocity and direction of the wind.
 

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Reply #4 - Dec 12th, 2009 at 9:07am

Brett_Henderson   Offline
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First off... if you can land an FSX C172 within a few feet of center-line, in a X-wind significant enough to have to contend with...  you're doing quite well. The drifting after the wheels are down means that you side-loaded a tad. That's a MSFS bug. It takes away the lateral friction during side-loading.. and doesn't give it back  Angry

As for X-wind technique.. the trick is to not have a technique. Almost every landing will have you crossing the controls at some point. Even a NO-wind landing will have you dealing with yaw, when you reduce power. If you carry say 1500RPM (C172) down to short final and then pull the power to idle.. it will yaw quite a bit at 70kias  Shocked

SOoooo.. just be continuously using the ailerons to keep the mass of airplane on center-line.. and the rudder to keep the nose pointed at the departure end; without really thinking about it as a X-wind technique... because more times than not, the wind will change in both directon and velocity.. even more so as you descend.

Now.. the strength of the X-wind will determine how far out you need to stop crabbing, and start landing. that's where personal prefernce comes in. The further out you transition to "landing mode" the more likely you are to run out of rudder. Also, being aware that whatever wind there is, it lessens near the surface.

What I try to do, is add a little downwind rudder to get a feel for the X-wind.. and that just sorta merges into the slip.
 
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Reply #5 - Dec 12th, 2009 at 12:25pm

olderndirt   Offline
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Brett_Henderson wrote on Dec 12th, 2009 at 9:07am:
First off... if you can land an FSX C172 within a few feet of center-line, in a X-wind significant enough to have to contend with...  you're doing quite well.
Wonderfully well - between the lights is my criteria.  Wing down to keep from going sideways along with enough opposite rudder to keep you aimed at the runway.  A little more power 'cause you're cross controlled then, as you flare, let it all swing back to normal and continue with the ailerons into the wind after you hit.
 

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Reply #6 - Dec 12th, 2009 at 1:34pm

snippyfsxer   Offline
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Thanks for all the info guys!  I don't know how to explain this, but "theoretically" I've been doing everything right, but somehow having it confirmed by you all has allowed me to quit focusing on the correctness of the technique and just do it better.
Brett_H:  There is something you said in your previous posts and that is "keep the nose pointed at the departure end."  I took the Carenado 182 up today for a few circuits and made it a point to keep my eyes focused on the FAR end of the runway instead of the pavement right below the nose.  You know what?  Somehow everything has come together.  My wind today was about 15 knots and gusting, blowing perpendicular to the runway and I was consistently able to hold the centerline through the flare and was touching down right on!  As far as the friction coefficients of FSX, well, as soon as the wheels touch...Easing the nosewheel back to center before it touches down and then recompensating for the weathervaning effect..well thats practice for another day I guess SmileyThanks guys
 
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Reply #7 - Dec 12th, 2009 at 2:02pm

DaveSims   Offline
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I have been told one reason to do the "kick out" method instead of slipping all the way down is passenger comfort.  Passengers don't seem to notice crabbing, but the aircraft side slipping is noticeable.
 
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Reply #8 - Dec 12th, 2009 at 2:06pm

C   Offline
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snippyfsxer wrote on Dec 12th, 2009 at 1:34pm:
Brett_H:  There is something you said in your previous posts and that is "keep the nose pointed at the departure end."  I took the Carenado 182 up today for a few circuits and made it a point to keep my eyes focused on the FAR end of the runway instead of the pavement right below the nose.  You know what?  Somehow everything has come together. 


You'll generally end up with far better touchdowns as well. It also works very well with long taxyways. Smiley
 
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Reply #9 - Dec 12th, 2009 at 2:13pm

Brett_Henderson   Offline
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DaveSims wrote on Dec 12th, 2009 at 2:02pm:
I have been told one reason to do the "kick out" method instead of slipping all the way down is passenger comfort.  Passengers don't seem to notice crabbing, but the aircraft side slipping is noticeable. 


Yeah.. those pesky passengers ..  Cheesy

What I've found though.. is that passengers are less squeemish about a slip, than they are about seeing the runway out the side window  Cheesy
 
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Reply #10 - Dec 12th, 2009 at 7:57pm

olderndirt   Offline
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Brett_Henderson wrote on Dec 12th, 2009 at 2:13pm:
Yeah.. those pesky passengers ..  Cheesy

What I've found though.. is that passengers are less squeemish about a slip, than they are about seeing the runway out the side window  Cheesy
An excellent point.  Passenger comfort sometimes has to be a lower priority than they'd like  Smiley.
 

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Reply #11 - Dec 12th, 2009 at 8:01pm

olderndirt   Offline
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C wrote on Dec 12th, 2009 at 2:06pm:
It also works very well with long taxyways. Smiley
Those lousy airport designers - they make them look so attractive  Smiley.
 

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Reply #12 - Dec 13th, 2009 at 3:02pm

aeroart   Offline
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My choice is to start the low wing, forward slip some distance before the end of the runway. What often gets neglected is that as you're rounding out to land and the airspeed decreases, aileron displacement needs to be increased to hold the low wing down and opposite rudder displacement needs to be increased to hold the airplane parallel with the runway. If you don't do these, the low wing will rise as the ailerons become less effective and the nose will turn toward the low wing, all because the controls are less effective at lower airspeeds. Hope this helps you.

Art
 
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Reply #13 - Dec 13th, 2009 at 6:59pm

Staiduk   Offline
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If anyone likes my trim tutorial (which is uploading now and SimTeeVee's taking *#$%@!! forever about it!) my next project is going to be a crosswind tute - 'cause I get to play with my Citabria. Working on it now. Smiley
 

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Reply #14 - Dec 14th, 2009 at 11:03am

olderndirt   Offline
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Discussions of crosswind landings are great 'cause they always remind me of something I could/should have done better.  At the time of the actual landing, finesse was not my biggest concern  Smiley.
 

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