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PostPosted: Mon Jan 16, 2017 9:01 am 
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Joined: Sun Jul 20, 2014 4:24 am
Posts: 20
Hi all,

Just want to get other simmers experience with crosswind takeoffs with any A2A GA aircraft and FSX/P3D (I don't care about real life; I'm talking about just in the sim.)

Whenever I take off with a crosswind from the right, meaning that I have to step on the left rudder pedal quite a lot to track the center line, as soon as I am airborne, I get somewhat violent rolling and yawing. I'm guessing it's the aerodynamics reacting to my left rudder pedal input, so am I supposed to just unload the left rudder on rotation? It doesn't seem as bad with cross wind from left, I think because you have to hold right rudder for p-factor, gyro, etc.

Anyone else experience this violent roll/yaw with left crosswind takeoff?

I'm really just trying to figure out if I'm doing something wrong.
Again, I'm not asking about real life... just the sim. This seems like a sim issue to me.

Thank you!
James


Last edited by szln6z on Mon Jan 16, 2017 9:22 am, edited 1 time in total.

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PostPosted: Mon Jan 16, 2017 9:09 am 
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Joined: Mon Sep 02, 2013 7:30 pm
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Location: Typically hanging around N07, 12N, KLDJ, KCDW
The technique is the same IRL as it is in the sim.

If the crosswind is from the left, you will need to apply full left aileron at the beginning of the takeoff roll. This left aileron will keep the airplane from sliding left/right of centerline.

Then use whatever amount of rudder is necessary to keep the airplane longitudinally aligned with the runway. The rudder should not be used to move the airplane to the left or right, the ailerons take on that task. If you drift right, apply more left aileron. If the airplane yaws right, then apply more left rudder to keep it aligned with the centerline but not so much as to steer it back to the centerline.

As the controls become aerodynamically more effective you can ease out the input needed to keep the plane tracking along the centerline and by the time you get airborne the airplane should smoothly transition into flight. Once in flight, ease out the cross control inputs and establish a crab in coordinated flight into the wind.

This is the same technique one would use on short final to align the aircraft with the runway before touchdown using a forward slip.

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Paramus Flying Club http://www.flyingclub.org


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PostPosted: Mon Jan 16, 2017 1:16 pm 
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Senior Airman

Joined: Sat Dec 13, 2014 11:38 am
Posts: 217
Location: Vancouver, BC
The technique also depends upon what style of steering gear is used and whether or not it is modeled in the simulation.

If you have a steerable nose-wheel hard-coupled to the rudder pedals as in the case of the Piper aircraft (Cherokee, Comanche) then you will track using the rudder pedals in an obvious manner with the rudder centered until the weight starts coming off the nose-wheel, at which point you need to transition into aerodynamic rudder control.

If you have a spring linked nose-wheel like on a 172, then you need to balance the cross-wind component with some rudder control right from the get go. The nose-wheel does not have a lot of authority on the ground and the aircraft will not necessarily steer toward whatever you have the rudders pressed. Instead the nose-wheel casters a bit, but the springs pull on it too, so you kind of have a steerable nose wheel, but not really.

If you have a freely castering nose-wheel like in a Lake LA-4 amphibian, then you are flying the aircraft at all times and the nose wheel is just there to hold the front end off the ground. The fin will cause the aircraft to turn into the wind at all times and you must counteract that effect at all times.

Same set of issues applies to conventional tail-wheel aircraft, except the control issues are exaggerated, and many tail wheel aircraft have freely castering (or lightly spring loaded) tail wheels.

Depending on the sim these control issues may or may not be simulated properly. They are in the case of the A2A aircraft that I have. With the steerable nose wheel aircraft there can be quite a sudden difference between the controls required for straight down the runway with weight on the wheels and when you rotate the nose wheel off the runway. If you don't correct promptly and smoothly then there is a bunch of jumping around.

Also, as you "rotate" the aircraft up then the torque effect (P-factor) will also twist the aircraft around.

You might be rotating rather suddenly which would exaggerate both effects. Try letting it happen a bit more naturally.

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