Top Rudder in Steep Turns?

Jaybird180

Jaybird180

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Jaybird180
I was reading an article on rudder coordination and it said that for medium and shallow banked turns rudder should always be moved with aileron and also removed in proportionate amounts. Tracking so far.

Then it said that in steep turns, when aileron is removed a little top rudder should be maintained to keep the turn coordinated.

I've never heard this before nor thought to try it. Anyone???
 
The only time I use rudder in an RV is take off, landing, acro, and formation flying. It flies pretty coordinated in turns all by itself.
 
I think you're referring to a supposed rudder input due to a possible slight out-turn aileron input due to overbanking tendency. All airplanes are different, but in general, you will not be needing any top rudder even if you have a slight bit of opposite aileron held for overbanking. And not all airplanes over bank.

Have you ever flown a glider? They demonstrate these things best. There is significant overbanking tendency, and you will likely need a little rudder in steep turns, but it will not be top rudder. It will be in-turn (bottom) rudder. So you may actually be holding slightly cross-controlled inputs during a perfectly coordinated steep turn.

You are more likely to need bottom rudder during steep turns due to the tail of the airplane trailing the shape of the turn. This causes a little relative wind to hit the vertical fin on the side opposite the direction of turn, requiring a slight bit of bottom rudder to yaw the airplane back into coordinated flight.

Somewhere out there is a diagram that illustrates this effect. Just like overbanking, not all airplanes display this yaw effect during steep turns. Both effects are more pronounced in gliders due to the long wingspan and distance between the wings and tail. My Pitts is so stubby that it displays neither of these characteristics. Ailerons and rudder are held neutral through the steepest of turns. Again, all airplanes are different, but I can't think of a reason to need top rudder during a coordinated steep turn unless the airplane is way out of rig.
 
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Don't know about top rudder. When I was taught thermalling in gliders, I was advised to use a little top aileron to maintain the bank angle once established in the spiral. It was needed to balance the lift between the wings because the outside wing was moving faster then the inside wing. I imagine the phenomenon is more pronounced in long slender glider wings than typical GenAv planforms.

Thinking about it, presuming that you're applying back pressure on the elevator to maintain altitude, in a 45-deg. bank your elevator is half rudder, and into the direction of the turn. Top (opposite) rudder negates that effect, and also relieves some elevator pressure.

Sounds like a good excuse to go fly and try it out (taking all necessary safety precautions). Keep the ball centered and the blue side up!
 
Echoing what has already been said, it is better demonstrated in a glider, perhaps the Schweizer 2-33 being one of the best demonstrators. In a slow steep turn (aka thermalling) it is not unusual for the over banking tendency to be so strong that you will have the aileron against the opposite stop to keep it for continuing to roll into the bank. The only way to get out of the turn is lower the nose to pickup speed(increase aileron effectiveness) or yaw the plane out of the turn with the rudder.

I suspect what the book is referring to is a situation like this where you are having to use opposite aileron to counteract the overbanking and opposite rudder to counteract the adverse yaw of ailerons. However this may be difficult to observe in that the only indicator would be the actual position of the rudders and how much pressure you are applying to the rudder. And it will vary a lot from airplane to airplane.

Brian
CFIIG/ASEL
 
brcase said:
Echoing what has already been said, it is better demonstrated in a glider, perhaps the Schweizer 2-33 being one of the best demonstrators. In a slow steep turn (aka thermalling) it is not unusual for the over banking tendency to be so strong that you will have the aileron against the opposite stop to keep it for continuing to roll into the bank. The only way to get out of the turn is lower the nose to pickup speed(increase aileron effectiveness) or yaw the plane out of the turn with the rudder.

I suspect what the book is referring to is a situation like this where you are having to use opposite aileron to counteract the overbanking and opposite rudder to counteract the adverse yaw of ailerons. However this may be difficult to observe in that the only indicator would be the actual position of the rudders and how much pressure you are applying to the rudder. And it will vary a lot from airplane to airplane.

Brian
CFIIG/ASEL
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The article indicated neutral aileron once bank angle has been established.
 
Jaybird180 said:
The article indicated neutral aileron once bank angle has been established.
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If the turn is very steep, is the rudder maybe used to keep the nose from dropping through the turn? :confused:

I don't know, I have not heard of this before.
 
Depends on the aircraft. In mine the rudder is not needed turning into a left steep bank. Due to P-Factor etc. the right turn needs rudder or the ball falls out and the nose starts to pull up and out of the turn. Once the turn is set, the rudder is no longer needed.
 
Ignore the article and don't try to overthink this -- just use whatever aileron is necessary to maintain bank angle, and whatever rudder is necessary to keep the ball centered. And whatever elevator is necessary to keep the nose where it belongs with respect to the horizon.
 
Ron Levy said:
Ignore the article and don't try to overthink this -- just use whatever aileron is necessary to maintain bank angle, and whatever rudder is necessary to keep the ball centered. And whatever elevator is necessary to keep the nose where it belongs with respect to the horizon.
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:yeahthat:
 
A steep "power turn" to the left, due to asymmetrical disk loading might cause skidding if you don't use top rudder. To the right, it would cause slipping and you'd need bottom rudder. A yaw string would be a real revelation <hint>.

dtuuri
 
Think about this. If you were at a 90 degree bank, your rudder would become your elevator. So at a steep bank (tending toward 60 degrees or so), you MAY want top rudder (top rudder is nose up when banked at 90 degrees right?) to keep the nose up. The ball wont be centered, but, again, if you were flying on your side (90 degrees) and coordinated on your side, the ball wouldn't be centered either.
 
dtuuri said:
A steep "power turn" to the left, due to asymmetrical disk loading might cause skidding if you don't use top rudder. To the right, it would cause slipping and you'd need bottom rudder. A yaw string would be a real revelation <hint>.

dtuuri
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Is that the test we talked about long time ago?
 
coloradobluesky said:
Think about this. If you were at a 90 degree bank, your rudder would become your elevator. So at a steep bank (tending toward 60 degrees or so), you MAY want top rudder (top rudder is nose up when banked at 90 degrees right?) to keep the nose up. The ball wont be centered, but, again, if you were flying on your side (90 degrees) and coordinated on your side, the ball wouldn't be centered either.
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No, not at all. You would NOT want/need that unless you are truly doing a turn on knife edge. Only aerobatic pilots do that. Otherwise, this would be terrible technique, and a very uncoordinated and inefficient way to turn, even if your bank angle is well below true 90 degrees. If your bank angle is so steep that you cannot complete a level turn without exceeding the G-limit or otherwise keeping the nose up, top rudder is not the answer. You need to reduce bank angle and use the proper amount of elevator, NOT rudder. There is little practical similarity between steep turns and knife edge flight that happens to have a turning component. In turns, even very steep ones, ALL of the life is carried by the wings. In knife edge flight, ALL of the lift is carried by the fuselage. There is NO crossover just because the turn gets steeper.
 
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Well, I guess you are NOT one of the ones that MAY want to use top rudder. No one is making you do it. If you don't want to do it, don't do it.
 
coloradobluesky said:
Well, I guess you are NOT one of the ones that MAY want to use top rudder. No one is making you do it. If you don't want to do it, don't do it.
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Everyone is free to use whatever "techniques" they want. I have NEVER heard anyone recommend using fuselage lift as a way to help keep a turn level. You can do it all you want, but since you posted on an internet forum, which is often read by impressionable student pilots, it's worth pointing out that using top rudder in steep turns for the reason you state is HORRIBLE TECHNIQUE. Nobody actually goes around turning with a true 90 degree bank angle...which of course WOULD require a lot of top rudder and pure fuselage lift rather than any wing lift. Not relevant to the subject of steep turns.

What you describe is only a little less horrible than saying "you might want to use extra rudder to skid the turn around if it's not turning as fast as you like". By the same token, do that all you want, but don't recommend it on an internet forum.
 
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Jaybird180 said:
Is that the test we talked about long time ago?
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I would think someone as curious about things as you are would have taped a yaw string to the cowl a long time ago. It mystifies me that you haven't done it and reported back here. Tufting the wing is always enlightening too. You might have to play with the positioning of the yaw string to find the "sweet spot" where local flow doesn't sweep it to one side or the other, but I'm sure you'd find it to be a worthwhile experiment. You could, for example, see the true effects of high power at low speed, say in a straight climb or steep turn, that the ball is incapable of revealing.

dtuuri
 
coloradobluesky said:
Think about this. If you were at a 90 degree bank, your rudder would become your elevator. So at a steep bank (tending toward 60 degrees or so), you MAY want top rudder (top rudder is nose up when banked at 90 degrees right?) to keep the nose up. The ball wont be centered, but, again, if you were flying on your side (90 degrees) and coordinated on your side, the ball wouldn't be centered either.
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Hmmm... I hope the disclaimer in your signature, "Truth is stranger than fiction, fiction has to be believable!" explains this convoluted logic (fiction). Otherwise, you're big trouble as a pilot.

dtuuri
 
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dtuuri said:
I would think someone as curious about things as you are would have taped a yaw string to the cowl a long time ago. It mystifies me that you haven't done it and reported back here. Tufting the wing is always enlightening too. You might have to play with the positioning of the yaw string to find the "sweet spot" where local flow doesn't sweep it to one side or the other, but I'm sure you'd find it to be a worthwhile experiment. You could, for example, see the true effects of high power at low speed, say in a straight climb or steep turn, that the ball is incapable of revealing.

dtuuri
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The devil made me (not) do it:D
 
Be mindful of the torque, P-factor, and various slipstream effects during pitch movements during a steep turn. Any time you pull back on the elevator, you change pitch. During the actual moment of pitch change, gyroscopic force comes into play, and as the pitch changes, down or up, P-factor and slipstream change the yaw and roll forces. And the air is usually a little bumpy, so, the focus is to keep the ball centered with rudder, and bank angle constant with aileron, whatever it takes; like a crosswind landing. Sometimes you'll have top rudder, sometimes bottom.
But if you pay attention, you will see that it will take some kind of rudder pressure to keep the ball centered with a constant bank angle.

Check this out: during a power on stall to the right, if you keep the ball centered, you will keep adding right rudder as the angle of attack is increased, and bank will try to increase, so opposite aileron will need to be continually applied as pitch (AoA) is increased so that when the stall occurs, if angle of bank has been maintained constant and ball has been kept centered, you will have lots of inside rudder with lots of opposite aileron to stay coordinated. All because of torque factors.
 
Top rudder is a slip. A slip is uncoordinated but fairly spin resistant. This is because the high wing is the wing that will have to drop in stall/spin wing drop. It has further to drop. It is more stable for some other reasons also.

Bottom rudder would be a skid, which is spin likely. In fact, pulling back on the stick, turning and pushing on bottom rudder, well, THAT is a spin entry.

So from a spin point of view, BOTTOM rudder is the one to worry about. Top rudder is uncoordinated but fairly spin resistant.

Slips on final to landing are pretty spin resistant. That's why you can do them. I mean if you can do them, that's why you can do them. Some don't like them or prohibit them. Surely everyone learns to slip during private training still, right?
 
Shepherd said:
I'm in awe at how many pilots have no idea what top or bottom rudder are.
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I have an ercoupe handing in the rafters of my barn sideways. It's pretty clear which rudder is the top one.
 
coloradobluesky said:
Top rudder is a slip. A slip is uncoordinated but fairly spin resistant. This is because the high wing is the wing that will have to drop in stall/spin wing drop. It has further to drop. It is more stable for some other reasons also.
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More incorrect analysis. Slip means opposing aileron and rudder inputs. During a turn, ailerons are neutral. If during a turn you apply top rudder and stall the airplane, the airplane will snap over very fast. Wing position has absolutely nothing to do with spin resistance. A power off slip as you would do to lose altitude is fairly spin resistant, but this is not what's happening when you're doing a turn and apply top rudder.
 
Anyone have a link to Jesse's slipping stall video? I think it can debunk some of what is being stated.

Edit: I think this is it. watching it now
http://youtu.be/5xDxj_CRfqY
 
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Ron Levy said:
Ignore the article and don't try to overthink this -- just use whatever aileron is necessary to maintain bank angle, and whatever rudder is necessary to keep the ball centered. And whatever elevator is necessary to keep the nose where it belongs with respect to the horizon.
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That's the ticket!!!! I read the Title and wondered what the OP was talking about then I realized I do this when I roll out of a steep bank, I just never thought about it. All I was doing was maintaining coordinated flight.
 
I would love to fly with Jesse sometime, I am sure he could hone my skills with his experience.
 
Jaybird180 said:
Anyone have a link to Jesse's slipping stall video? I think it can debunk some of what is being stated.
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What's there to debunk?? A slipping turn means you are holding slipped inputs - as in aileron deflection one way, and rudder opposite. This is very spin resistant. Now enter a normal coordinated turn with neutral aileron and stall the airplane with full top rudder while keeping the ailerons neutral, and you will get a very different result in most airplanes. If you don't believe, get with an instructor and go try it. And a 172 at forward CG is not the best airplane to demonstrate stall/spin characteristics. Lots of airplanes will react much more willingly to mishandling.
 
You don't have to have aileron deflection, or even rudder deflection to be slipping, (although the classic aileron and opposite rudder will make a slip).

Slipping has to do with the direction of the relative wind in relation to the airframe.
 
I recall the definition of a slip is too much bank for the rate of turn.

Or too little rate of turn for a given bank angle, which is really saying the same thing.
 
FastEddieB said:
I recall the definition of a slip is too much bank for the rate of turn.

Or too little rate of turn for a given bank angle, which is really saying the same thing.
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A slip is opposite rudder and aileron, a skid is too much rudder
 
You don't have to be turning to slip. You don't have to be depressing the rudder.

Try this definition for a slip:
A slip is an aerodynamic state where an aircraft is moving somewhat sideways as well as forward relative to the oncoming airflow or relative wind.
 
So much confusion about stick and rudder...and it's understandable because (modern) airplanes are designed so you probably will never learn it - unless you have an instructor who is fanatical about it. But I suggest you poke around airbum.com. There is an excellent explanation about the rudder in one of Budd Davisson's training articles.
 
coloradobluesky said:
Try this definition for a slip:
A slip is an aerodynamic state where an aircraft is moving somewhat sideways as well as forward relative to the oncoming airflow or relative wind.
Click to expand...

You could say the exact same thing about a skid.
 
FastEddieB said:
I recall the definition of a slip is too much bank for the rate of turn.

Or too little rate of turn for a given bank angle, which is really saying the same thing.
Click to expand...

The fact that this occurs we agree on. Not sure if thats a complete definition
 
RoscoeT said:
More incorrect analysis. Slip means opposing aileron and rudder inputs. During a turn, ailerons are neutral. If during a turn you apply top rudder and stall the airplane, the airplane will snap over very fast. Wing position has absolutely nothing to do with spin resistance. A power off slip as you would do to lose altitude is fairly spin resistant, but this is not what's happening when you're doing a turn and apply top rudder.
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Most of the time, you can hold opposite aileron and rudder and still be perfectly coordinated. You have to present the side of the aircraft into the relative wind to have a slip (or skid for that matter). Control inputs aren't particularly relevant, coordination to the relative wind is what it is all about.

BTW, You never will enter a spin from a slip, as the wing comes over the slip will turn to a skid. Spins are always entered from a skid. It's difficult to inadvertently enter a spin from a slip as the plane typically loses rotational energy coming over and if you don't maintain full deflections in most planes people train in, you will just bobble into a level stall recovery. If you are skidding the turn and stall though, you stall low (retreating) wing first and she tuck right around in a hurry.
 
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