How to interpret the yaw string?

[Nealius]

Hoping to get some SME input here:

 

I'm familiar with the good old slip indicator: "Step on the ball." The yaw string is a bit new to me and after observing its behavior I'm not sure what to do with it. Specifically the following points:

 

1. Should I be "Stepping on the string" or opposite the string?

 

2. There are times the string and the ball do not agree at all. I've seen them showing opposites, I've seen the string showing no slip while the ball shows slip, and in certain maneuvers like aileron rolls the string often indicates some weird things, like needing rudder in the direction of roll while knife-edged 90 degrees--which normally requires opposite rudder to keep the nose straight in any other stick-and-rudder aircraft that I've flown in DCS. 

 

How should I be interpreting what the string is telling me, and are there times I should be prioritizing the string over the ball, or vice versa? 

 

And on a related tangent, any tips to prevent overbank when making quick banks? I find the Tomcat much easier to overbank than the F-86 and F-5E. 

 

Edited December 9, 2020 by Nealius

[DD_Fenrir]

Hi Nealius, not a Tomcat SME but did a great deal of glider training in the past so VERY familiar with yaw strings!

 

1. Step opposite the string - tail of string flows right, step left

2. At very high Angles of Bank referencing the yaw string is probably unwise as you will be using Beta (yaw angle of attack) to (a) generate lift with the airframe (b) vector some of your thrust to resist gravity. Therefore you should NOT want to straighten the string in those instances. 

 

[Wildwind]

5 hours ago, Nealius said:

Hoping to get some SME input here:

 

I'm familiar with the good old slip indicator: "Step on the ball." The yaw string is a bit new to me and after observing its behavior I'm not sure what to do with it. Specifically the following points:

 

1. Should I be "Stepping on the string" or opposite the string?

 

2. There are times the string and the ball do not agree at all. I've seen them showing opposites, I've seen the string showing no slip while the ball shows slip, and in certain maneuvers like aileron rolls the string often indicates some weird things, like needing rudder in the direction of roll while knife-edged 90 degrees--which normally requires opposite rudder to keep the nose straight in any other stick-and-rudder aircraft that I've flown in DCS. 

 

How should I be interpreting what the string is telling me, and are there times I should be prioritizing the string over the ball, or vice versa? 

 

And on a related tangent, any tips to prevent overbank when making quick banks? I find the Tomcat much easier to overbank than the F-86 and F-5E. 

 

 

The online book that Victory linked me to in another thread has a page that addresses slip extensively, including the differences between the yaw string (which purely indicates slip) and the ball (which is actually an inclinometer, and indicates inclination, which often but not always reflects slip).   https://www.av8n.com/how/htm/snaps.html

 

I was just reading this section this morning before work, in fact.

[Nealius]

Wow, TIL the "slip indicator" isn't actually for slip, but is technically an inclinometer. 

[Wildwind]

13 minutes ago, Nealius said:

Wow, TIL the "slip indicator" isn't actually for slip, but is technically an inclinometer. 

Yep, that was a new one on me, too.  As was the connected realization that I've been drawing the wrong conclusions from it.  Now I am doing a bunch of flying around in the F-14 with the seat jacked up so I can see the string clearly and practicing coordinated turns in an effort to exorcise my bad habits.

 

The most surprising discovery was that I have been using too much rudder in gentle turns (and thus skidding without realizing it) and not nearly enough in really hard turns.  Fixing my habits is going to take a lot of practice, I can tell.

[Nealius]

1 hour ago, Wildwind said:

Yep, that was a new one on me, too.  As was the connected realization that I've been drawing the wrong conclusions from it.  Now I am doing a bunch of flying around in the F-14 with the seat jacked up so I can see the string clearly and practicing coordinated turns in an effort to exorcise my bad habits.

 

The most surprising discovery was that I have been using too much rudder in gentle turns (and thus skidding without realizing it) and not nearly enough in really hard turns.  Fixing my habits is going to take a lot of practice, I can tell.

 

Hard turns are where I struggle. It takes only a fraction of a second to go from level to a high angle of bank, and my foot simply can't time that fraction of a second with my arm. 

[Spiceman]

On 12/9/2020 at 7:50 PM, Nealius said:

Wow, TIL the "slip indicator" isn't actually for slip, but is technically an inclinometer. 

It shows the state of balance between centrifugal force and gravity. Slip is derived information from the indication. 

Edited December 11, 2020 by Spiceman

[IronMike]

On 12/10/2020 at 2:05 AM, Wildwind said:

Yep, that was a new one on me, too.  As was the connected realization that I've been drawing the wrong conclusions from it.  Now I am doing a bunch of flying around in the F-14 with the seat jacked up so I can see the string clearly and practicing coordinated turns in an effort to exorcise my bad habits.

 

The most surprising discovery was that I have been using too much rudder in gentle turns (and thus skidding without realizing it) and not nearly enough in really hard turns.  Fixing my habits is going to take a lot of practice, I can tell.

I admire that kind of dedication. Well done!