Rudder causes bank

[Lion13]

When I apply some rudder to side slip, the a/c banks in the direction of trhe rudder applied (left rudder = left bank).

 

Is this normal, a problem with my controls setup/controllers, a bug or reality?

 

Thanks

[mattch49]

Just reality :)

[King_Hrothgar]

That's standard aircraft behavior. Though I'm sure someone at some point has designed a plane that doesn't roll with rudder input (probably on a bet or dare), I have never heard of it.

[Svend_Dellepude]

AFAIK the bank comes from sideslip chancing the geometry of your wings in releation to flight heading. The advancing wing will tend to rise and the retreating tend to drop because of the assymetric airflow over over the wings.

[NeilWillis]

Swept wings also increase that tendency. As the advancing wing swings forwards, there is a large increase in frontal area, at the same time the retreating wing frontal area reduces, and the asymmetric lift that results causes the banking.

 

Dihedral also exposes more of the underside of the advancing wing, which exacerbates the effect due to the slipstream acting upon it.

[Lion13]

re: rudder causes bank

 

I soloed in a Cessna 152 Aerobat, and used to crab it in cross wind landings ( as opposed to the cross controlled technique). AIRC it did not bank when side slipping. It's understandable with a swept-wing a/c.

 

Thank y'all for the clarification.

[FlankerKiller]

are you sure you didn't just reflexively counter the roll with the ailerons? I've got some stick time in a 172 and it would dip a wing if you just applied rudder.

[Zabuzard]

This should be normal a behavior.

For example if you attempt to do a left rudder turn you need to hold the stick fully right to counter and stay straight^^

[Kaiza]

I soloed in a Cessna 152 Aerobat, and used to crab it in cross wind landings ( as opposed to the cross controlled technique). AIRC it did not bank when side slipping. It's understandable with a swept-wing a/c.

 

Thank y'all for the clarification.

 

 

 

That's because crab technique doesn't use rudder/sideslip. Your relative airflow is straight, you crab relative to the runway but remain 'into wind'.

 

Cross controlled effect is called so because of this very effect of rudder. In crosswind if you apply rudder to straighten the aircraft relative the runway you have to apply opposite aileron to counter the roll thus: cross controlled.

 

If you cast your mind back you were probably demonstrated this on your first flight as part of the "secondary effects of controls".

Edited October 30, 2015 by Kaiza

[Holbeach]

Maybe he's thinking about the part, kicking it straight using the rudder, to align with the runway, just before touchdown after a crab approach.

 

 

..

[Lion13]

RE: rudder causes bank

 

The landing technique the instructor used was to lower the wing that was into the cross wind and used the rudder to maintain runway alignment (cross controlled).

 

My technique was to apply rudder to point the nose in to the cross wind enough to maintain runway alignment. I do not recall having to compensate for any bank, probably because not much was required, so its likely i did so.

 

Tthe crosswind technique, required almost full right aileron for the cross controlled method and a lot of rudder, it felt awkward, where as the crabbing style felt natural.

 

I do remember my instructor saying, ' if you don't get her pointed straight before you touchdown you'll bend something.'

 

This was over forty years ago.

[Kaiza]

 

My technique was to apply rudder to point the nose in to the cross wind enough to maintain runway alignment. I do not recall having to compensate for any bank, probably because not much was required, so its likely i did so.

.

 

This is actually the cross controlled technique. You would have had to apply opposite aileron or you would have rolled towards the rudder and into the ground. It was probably so natural to compensate for the roll you didn't notice.

 

In the crab technique you apply no rudder and fly in angled off from the runway like a crab walking across a beach sideways. In extreme crosswind you might even be looking through your side window at the runway. You then either kick it straight in the flare or if you aircraft is designed to do so, land angled off.

[strikeeagle]

The next time you fly, climb up, and hold the rudder in what ever direction you want and let go of the yoke. The airplane WILL bank in that direction.

[zaelu]

Soloing an aircraft and not knowing such basic fact I think is a bit worrying.

 

jump to 0:40

 

 

some explanations:

 

 

here is how it returns

 

 

and here:

 

http://www.empire-aviation.com/flight-instructors/john-e-mclain/understanding-the-use-of-rudder.html

Edited November 3, 2015 by zaelu

[SayusiAndo]

Ok, it is clear for me why it happens. What is the situation with planes having FBW systems? Are they also experience this? It is not overwritten by the code?

[Vitesse2l]

Soloing an aircraft and not knowing such basic fact I think is a bit worrying.

 

Well, the OP did say it was forty years ago! I can barely remember what I did 40 minutes back...

[Cool Breeze]

The rudder also causes a rolling motion because it is out side of the long axis of the aircraft and produces a bit of torque to the airframe. The aerodynamic effects on the wing just exacerbate the roll.

 

Ok, it is clear for me why it happens. What is the situation with planes having FBW systems? Are they also experience this? It is not overwritten by the code?

FBW systems helps the aircraft maintain stablility within certain parameters and limit control forces that may break the aircraft or incapacitate the pilot. Pilots can still perform cross control maneuvers and the like. Try flying the Su-27 with the FBW system disengaged, I think it's the "S" key. It's a very wild ride!

 

http://www.howitworksdaily.com/what-is-a-fly-by-wire-system/

Edited November 6, 2015 by Cool Breeze

[Cool Breeze]

The landing technique the instructor used was to lower the wing that was into the cross wind and used the rudder to maintain runway alignment (cross controlled).

 

My technique was to apply rudder to point the nose in to the cross wind enough to maintain runway alignment. I do not recall having to compensate for any bank, probably because not much was required, so its likely i did so.

 

Tthe crosswind technique, required almost full right aileron for the cross controlled method and a lot of rudder, it felt awkward, where as the crabbing style felt natural.

 

I do remember my instructor saying, ' if you don't get her pointed straight before you touchdown you'll bend something.'

 

This was over forty years ago.

A light crosswind may require only a bit of rudder input. A higher crosswind would require more rudder, and thusly requiring adding aileron input to counteract the rolling moment.