coordination on steep turn exit

[GeorgeC]

In the coordination exercise commonly and incorrectly referred to as "dutch rolls", we learn about adverse yaw and the correct amplitude and phasing of rudder and aileron inputs. When done correctly, a point on the horizon does not appear to move, and the roll "feels right", presumably meaning positive Gs and no lateral acceleration.

If I'm rolling out of a steep turn, I'm on the rudder the same way, so that it "feels right" and a point on the horizon does not appear to move. When I do so, however, the ball is all over the place, and I don't understand why.

The slip indicator has a slight U shape to it, so any negative Gs will push the ball up one way or the other; the only thing I can think of is that I'm pushing the nose down and unloading without realizing it.

 

[MauleSkinner]

The slip indicator has a slight U shape to it, so any negative Gs will push the ball up one way or the other

I can pretty much guarantee you’re not putting negative G on the airplane during the rollout. If you’re trying to roll out of a steep turn with the same sight picture as a Dutch toll, you’re not maintaining coordinated flight during the rollout.

Don’t look at the ball. Just keep your butt in the center of the seat.

 

[midlifeflyer]

If you’re trying to roll out of a steep turn with the same sight picture as a Dutch toll, you’re not maintaining coordinated flight during the rollout

 

[GeorgeC]

Don’t look at the ball. Just keep your butt in the center of the seat.

Right. If I keep the ball centered during the rollout, it feels awful. The question is, why?

 

[MauleSkinner]

Right. If I keep the ball centered during the rollout, it feels awful. The question is, why?

Mostly because you’re not keeping the ball centered, but you’re using the ball as a reference. The ball is an indirect indication of yaw, and “chasing” the ball can actually result in it indicating opposite of the actual yaw of the airplane during dynamic changes.

 

[dtuuri]

When done correctly, a point on the horizon does not appear to move...

"Does not appear to move much," is how I would say it. You can't instantly go from one side to the other, so there's a second or two where you're in a side slip if in fact you succeed in keeping the point stationary. I'd go for the "feel" and the ball will stay in the center, but the point will move a little. I like making back-to-back 90° steep turns, then 45°s and so on until not turning much at all, which is the Dutch Roll you speak of.

 

[midlifeflyer]

Mostly because you’re not keeping the ball centered, but you’re using the ball as a reference. The ball is an indirect indication of yaw, and “chasing” the ball can actually result in it indicating opposite of the actual yaw of the airplane during dynamic changes.

I'm fairly well convinced people do steep turns better with the instruments covered.

 

[brcase]

Most likely you are overcontrolling the Rudder. The only time you need to change the rudder pressure is when you deflect the ailerons. You may need to hold a bit of rudder during the turn due to overbanking tendencies. As you deflect the ailerons it will take a bit more rudder to correct for the adverse yaw. The faster you roll in and out of the turn the more rudder you need, if you start your roll out early and do a slow roll out (maybe 3 seconds to go from 45 to level, which I think is quite slow) you should need almost no additional rudder for the roll out. I personally like the faster roll in and roll out.

Brian
CFIIG/ASEL

 

[dtuuri]

If I'm rolling out of a steep turn, I'm on the rudder the same way, so that it "feels right" and a point on the horizon does not appear to move. When I do so, however, the ball is all over the place, and I don't understand why.

When rolling out of a steep turn you need to lead the rollout by 10° or so. We talkin' 'bout practice, man.

 

[Clip4]

In the coordination exercise commonly and incorrectly referred to as "dutch rolls", we learn about adverse yaw and the correct amplitude and phasing of rudder and aileron inputs. When done correctly, a point on the horizon does not appear to move, and the roll "feels right", presumably meaning positive Gs and no lateral acceleration.

If I'm rolling out of a steep turn, I'm on the rudder the same way, so that it "feels right" and a point on the horizon does not appear to move. When I do so, however, the ball is all over the place, and I don't understand why.

The slip indicator has a slight U shape to it, so any negative Gs will push the ball up one way or the other; the only thing I can think of is that I'm pushing the nose down and unloading without realizing it.

First question, are you really doing a steep turn or are you doing a turn with just 45° of bank?

While 45° bank is where a steep turn normally occurs, 45° bank may not be a steep turn.

If you are really doing a steep turn, you have to use aileron opposite the direction. So when rolling out, you really are not reversing the aileron input.

 

[luvflyin]

In the coordination exercise commonly and incorrectly referred to as "dutch rolls", we learn about adverse yaw and the correct amplitude and phasing of rudder and aileron inputs. When done correctly, a point on the horizon does not appear to move, and the roll "feels right", presumably meaning positive Gs and no lateral acceleration.

If I'm rolling out of a steep turn, I'm on the rudder the same way, so that it "feels right" and a point on the horizon does not appear to move. When I do so, however, the ball is all over the place, and I don't understand why.

The slip indicator has a slight U shape to it, so any negative Gs will push the ball up one way or the other; the only thing I can think of is that I'm pushing the nose down and unloading without realizing it.

I don't think you should be keeping a spot on the windshield on a point on the horizon like when doing the dutch roll thingy. In those you are going straight ahead. In a steep turn you are turning. If you try to lock the spot on the point while still in the turn I can see how it's going to be weird.

 

[dmspilot]

In the coordination exercise commonly and incorrectly referred to as "dutch rolls", we learn about adverse yaw and the correct amplitude and phasing of rudder and aileron inputs. When done correctly, a point on the horizon does not appear to move, and the roll "feels right", presumably meaning positive Gs and no lateral acceleration.

If I'm rolling out of a steep turn, I'm on the rudder the same way, so that it "feels right" and a point on the horizon does not appear to move. When I do so, however, the ball is all over the place, and I don't understand why.

The amount of rudder you use is always proportional to the amount of aileron you use and thus, the roll rate. The coordination exercise sometimes called "Dutch rolls" uses very high roll rates both to make the point of the maneuver more obvious (high roll rate = more adverse yaw) and to prevent the airplane from actually turning (changing heading) during the maneuver. Steep turns are rarely performed with equivalent roll rates outside of aerobatics. The amount of rudder is not equivalent. Also, if you're doing a steep turn to the right, you will need much less left rudder during the rollout due to left turning tendencies.

I'm also uncertain how it would even be possible to roll out of a steep turn without changing heading. You're still turning. Attempting to stop the turn instantaneously is not correct technique.

 

[Ed Haywood]

Attempting to stop the turn instantaneously is not correct technique.

Unless you are competing in aerobatics.

 

[dmspilot]

Unless you are competing in aerobatics.

I said that.

 

[MRC01]

... If I'm rolling out of a steep turn, I'm on the rudder the same way, so that it "feels right" and a point on the horizon does not appear to move. When I do so, however, the ball is all over the place, and I don't understand why. ...

The ball has a lag in its response, so it's no good during dynamic maneuvers. If you're following the ball while maneuvering then you're behind the airplane.

... Don’t look at the ball. Just keep your butt in the center of the seat.

Exactly. Another way to describe it is tune in to your butt-o-meter. If you feel pressure on one side of your butt, push on that rudder pedal just enough to eliminate the pressure. These G-forces are instantaneous, unlike the ball which has a lag time, so you won't be behind the airplane. With practice you learn to anticipate it and use the rudder pedals to prevent any butt-o-meter lateral pressure in the first place.

 

[Lindberg]

When rolling out of a steep turn you need to lead the rollout by 10° or so. We talkin' 'bout practice, man.

Even 10° is likely too late for real steep turns. I'd use half the bank angle. So start 30° before the desired heading for a 60° banked turn. And do it smooth and slow, just like the entry.

 

[MauleSkinner]

Even 10° is likely too late for real steep turns. I'd use half the bank angle. So start 30° before the desired heading for a 60° banked turn. And do it smooth and slow, just like the entry.

In faster airplanes (like jets) where the turn rate is slower, 10 degrees works well, but in typical trainers, 1/2 the bank angle is a good gouge.

 

[Ed Haywood]

Dutch rolls are better in aircraft with centerline seating. I do them as warmup before every acro practice session in my Decathlon. I have a contrasting mark at eye level on my windshield brace. I use that as a "gunsite" ... put it on a spot of sky and hold it while I roll 45-45. No turns.

If you want to dutch roll out of a steep turn, you'll need to fly it like an aerobatic turn. Unload pitch to stop heading change, then roll out. Your ball depends on positive G load to work, so it will become useless until you approach wings level.