Auto Coordination

Not sure if anyone can answer this but..

 

In MSFS, there is an option to auto coordinate your turns, am I correct in understanding that airliners will also do this automatically so the pilot doesn't normally need to apply rudder?

Click on the option for autorudder in your FSX Realism settings. Edited March 12, 2019 by mrzippy

In the sim, the need for yaw correction varies with each specific implementation, but the autocoordination feature works on all fixed wing aircraft, piston or turbine. In real life, there's no such feature (ignoring Ercoupes and such, which are mechanical), but jets generally require little rudder input for a turn or normal maneuvers since the adverse yaw is minimal due to wing/aileron design.Many jets and turboprops, and some others, have a yaw damper, which isn't the same thing.

Yes Zippy, I mean real aircraft. I've heard different things as to whether turns are coordinated automatically or not.

Yes Zippy, I mean real aircraft. I've heard different things as to whether turns are coordinated automatically or not.

 

No. Generally (and it varies from aircraft to aircraft and type) the pilot is expected to apply rudder to compensate for adverse yaw caused by ailerons. Where you have been confused is with the Yaw Damper which is found in aircraft with swept wings, and which compensates for Dutch Roll.

 

You can look those terms up on Google.

To add to the above, rudder is rarely required for Gyroplanes to manage a co-ordinated turn. Small GA will always require some `footwork` to balance a turn. Heavy GA often need leading with rudder, while swept-wing jets rarely need much rudder for co-ordination.

 

Perhaps you could expand on what you view as an `airliner`? If you mean modern jets, then the yaw damper usually allows the pilot to keep their feet more-or-less on the floor. Try the same with a Dash-8 400 and the aircraft will spin into the scenery - 4,800hp a-side will do that to you.

 

Historic aircraft usually require some - or much - rudder. There is no generic `one-size fits all` answer to your question.

Okay, guess I was thinking like on a 747 or Airbus 300 series.

Okay, guess I was thinking like on a 747 or Airbus 300 series.

 

Older generation airliners then:

The 747 has a split rudder, designed expressly to reduce force input possible and allow a degree of rudder compensation for out-of-trim forces

A300 has had an Airworthiness Directive designed to limit rudder application following a fatal crash of an aircraft in 2001.

 

You can look both these up online if you want further information.

 

More modern airliners have fly-by-wire with completely different control laws.

With autorudder on in fsx the rudder moves in the same direction as the yoke automatically when only rudder is applied.

 

This means that crabbing is then not possible.

While crabbing you apply the yoke and rudder in opposite directions on purpose.

 

Crabbing is an important maneuver needed for landing in crosswind. It is used every day all over the world.

(for more info on crabbing during approach see:

https://en.m.wikipedia.org/wiki/Crosswind_landing

)

 

Every real aircraft must be able to crab. So on real aircraft there won't be such a thing as 'rudder auto coordination' that always moves the rudder to the same side as the ailerons.

 

Even in fly-by-wire controlled aircraft crabbing pilot input will still result in crabbing output.

The Fly-by-wire computer reads pilot input, then keeps the plane within stable limits but does what the pilot asks as much as possible.

 

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Auto-rudder in fsx is most likely just an option that Microsoft added so people could use the early joysticks with fsx. Those early joysticks had no twist-function to control rudder. (and using arrow keys for rudder is not much fun.)

 

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(A turn coordinator is an instrument the pilots can read. Similar to a compass. A turn coordinator does not steer the plane in any way.)

While crabbing you apply the yoke and rudder in opposite directions on purpose.

That describes a slip.

 

This means that crabbing is then not possible.

I think you mean slipping isn't possible. Crabbing is just turning into the wind to give a desired path over the ground, and is done in coordinated flight, not cross controlled. You're probably thinking of crabbing down final then kicking it straight, or crabbing at first, then going into a slip on the latter part of final.

 

(for more info on crabbing during approach see:

https://en.m.wikipedia.org/wiki/Crosswind_landing

)

This link has an excellent description of crabbing, then changing to a slip or kicking it straight (it calls it Decrab).

 

Every real aircraft must be able to crab.

And they can. But a very few cannot slip, such as the two-control version of the Ercoupe/Aircoupe, which have no rudder control -- it's tied to aileron deflection, and not in a linear fashion, though it is mechanical. In a crosswind, the Ercoupe actually lands in a crab (the gear is designed to take it). Jets with the engines slung below the wing often don't have enough clearance to slip when next to the ground, thus must crab down final and then kick it straight at the last second. A very few aircraft have some sort of "crosswind landing gear" which turns in respect to the aircraft itself. On certain Cessna singles (tailwheel type, C-185 for example), the crosswind gear (when so equipped) snaps into position on touchdown, letting the aircraft continue to crab. Reportedly not many folks like that gear (I've flown 180/185 but not with xwind gear). The B-52 has crosswind gear, but the crew turns the gear sideways (to parallel the runway) before touchdown.

 

Auto-rudder in fsx is most likely just an option that Microsoft added so people could use the early joysticks with fsx. Those early joysticks had no twist-function to control rudder. (and using arrow keys for rudder is not much fun.)

You've got the right general idea, but it had nothing to do with a twist grip. Rudder pedals were, indeed, available. The autocoord was for people who had no means of rudder control, except for the keyboard (awkward is being kind).

 

(A turn coordinator is an instrument the pilots can read. Similar to a compass. A turn coordinator does not steer the plane in any way.)

A turn coordinator is an instrument that replaces the turn-and-bank instrument, and has no relationship to a compass. Its tilting "airplane" shows rate of turn, with the marking line in either direction showing the "standard rate turn" which is 3º per second, or a turn rate that will turn 360º in 2 minutes (thus the 2 MIN label on many of them).

Edited March 19, 2019 by lnuss

The turn coordinator and is an instrument a pilot can read. So is a compass.

Nothing wrong with that statement I made.

 

I said it to make clear it's not some system that magically work like "autorudder". The turn coordinator does not controll, do, or coordinate anything.

The turn coordinator and is an instrument a pilot can read. So is a compass.

That's very true. But you said, "A turn coordinator is an instrument the pilots can read. Similar to a compass." and the TC is not similar to a compass.

 

With your clarification above I see you were intending to say something like, ""A turn coordinator is an instrument the pilots can read, just as a pilot can read a compass or an altimeter, but it has nothing to do with autocoordination." But it didn't come across that way.

I know this is an old thread, but for the information of people, it was discussed recently on Mentour's YouTube channel. The yaw damper does indeed make it so the pilot of, for example, a 737 only normally works the yoke, while the computer will keep the flight co-ordinated.

the computer will keep the flight co-ordinated.

That statement isn't totally true. I'm not saying that you're wrong about the yaw damper helping, because it does help, but it's not the whole answer, AND:

 

That is NOT the purpose of the yaw damper. It is NOT an auto-coordination device, though it can do much of that. As mallcott said above, the purpose is to "dampen" Dutch roll, though it does (as he also says) help to a degree when applying aileron. A major reason that swept wing jets don't need much rudder application by the pilots is that the ailerons (and/or spoilers, depending on the design) are designed (combined with the odd effects of the swept wing) to have very little adverse yaw, unlike more conventional aircraft in which that adverse yaw from the aileron input can be considerable. Even relatively modern light aircraft (C-172, etc.) need a LOT less rudder than older aircraft (Cub, Champ, etc.), due to aileron design.

 

See this Wiki link for a bit more info. You might also see this Dutch roll article.

Just discovered this thread and want to add a bit of additional info.

 

All the jets I've flown IRL are usually flown with the feet on the floor, except when pushing off the crab angle during a crosswind landing.

 

On airliners (even the older ones like the 767) the yaw damper does have the additional function to auto coordinate the turns.

You can observe this function by looking at the flight controls page when rolling (rapidly) into a turn and you can see a very noticable rudder deflection.

 

Also the flight manuals usually provide this info. E.g. in case of the 767 it says:

The yaw damper systems improve turn coordination and dutchroll damping

 

In FSX/P3D the yaw damper (in most cases) incorrectly takes away most of the rudder control.

 

Hope this clarifies things a bit :)