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F-5 no rudder input needed to maintain coordinated turns


SMH

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2 hours ago, bbrz said:

Definitely not and one of both obviously couldn't be the result of adverse yaw. 

"Rather, it generally creates inefficiency in flight and possibly physical discomfort among passengers as the aircraft skids and slips from side to side while conducting uncoordinated turns."

https://inspire.eaa.org/2020/08/12/adverse-yaw-what-is-it/

"
 However, in the beginning of a turn, when the ailerons are being applied in order to bank the airplane, the ailerons also cause an adverse yaw of the airplane. For example, if the airplane is rolling clockwise (from the pilot point of view), the airplane yaws to the left. It assumes a crab-like attitude relative to the wind. This is called a slip. "

https://en.wikipedia.org/wiki/Skid_(aerodynamics)

 

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6 hours ago, SMH said:


What about the F-86, MiG-15 and A-10C which now do the same?

When was this changed on all these planes? Why?


Also, is "slipping and skidding" not "adverse yaw"?

It used to. When was it changed?

I feel like I'm flying an oversimplified sim now. 

Also, you seem to be contradicting each other. cofcorpse is saying we should see adverse yaw and that we do and that my track shows it (despite my screen capture showing none). Yo-Yo is saying that we shouldn't see adverse yaw at all and that we don't. How can it be both?

 

Adverse yaw is a matter of HIGH AOA and ailerons deflected at almost full angle - Do you see the last reason as you are already in steady turn? And, by the way, the turn itself can be not at high AoA.
This effect is more or less pronounced at the start of banking, yes, as the ailerons are deflected, but in a turn no rudder input is required for certain planes.

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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1 hour ago, Yo-Yo said:

Adverse yaw is a matter of HIGH AOA and ailerons deflected at almost full angle - Do you see the last reason as you are already in steady turn? And, by the way, the turn itself can be not at high AoA.
This effect is more or less pronounced at the start of banking, yes, as the ailerons are deflected, but in a turn no rudder input is required for certain planes.


Yeah, fly-by-wire planes. These aren't. 

When was this change implemented? It didn't used to be this way. And again, the F-86, MiG-15 and A-10C behave this way now too. I'm sure they didn't before, I used to have a reason to use rudder.

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6 hours ago, SMH said:


Yeah, fly-by-wire planes. These aren't. 

This has nothing to do with FBW. Even a 767 will show a noticeable amount of adverse yaw when you are applying full aileron at the start of a turn at low speed.

Manual rudder input is not required and you don't apply rudder, because the yaw damper turn coordination function will immediately counteract adverse yaw.

 

Furthermore on most aircraft the vertical tail itself will be sufficient for the adverse yaw to be removed after reaching a steady bank angle.  

That's one of the reason why there's one bolted onto the fuselage. If it wouldn't remove sideslip on its own, e.g. flying in turbulence would be next to impossible.

 

Btw. if aileron application would cause skidding, it would be the opposite of adverse, (too much) proverse yaw.

 


Edited by bbrz
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On 5/27/2021 at 7:54 PM, 303_Kermit said:

Why everyone who ever flew a glider, or Cessna 40 thinks that he's FM expert?

  Knowing enough to think you know everything, but not knowing enough to know you don't 😉

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Де вороги, знайдуться козаки їх перемогти.

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22 minutes ago, cofcorpse said:

FM of F-5E, MiG-15, F-86 hasn't been changed quite for a while. As far as I know, nothing was done specifically to remove or add this effect. 


So if I can prove they used to exhibit far more adverse yaw you'll admit something changed accidentally?

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10 minutes ago, SMH said:


So if I can prove they used to exhibit far more adverse yaw you'll admit something changed accidentally?

Yes, if there is evidence of different behavior in different versions, this is a reason to figure out why this happened.

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9 hours ago, SMH said:


So if I can prove they used to exhibit far more adverse yaw you'll admit something changed accidentally?

F-5 exhibits enough adverse yaw with initial roll into turn, about a ball from center as I said before. It also exhibits great yaw stability and yaw damping that is why you see almost no ball deflection when in stable turn with no aileron deflection. You sure you have your terms and definition of what you actually have a problem with in check?


Edited by Golo
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22 hours ago, Golo said:

F-5 exhibits enough adverse yaw with initial roll into turn, about a ball from center as I said before. It also exhibits great yaw stability and yaw damping that is why you see almost no ball deflection when in stable turn with no aileron deflection. You sure you have your terms and definition of what you actually have a problem with in check?

 

I disabled the yaw dampener in my test track.

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36 minutes ago, SMH said:

I disabled the yaw dampener in my test track.

OK, but that is for yaw damping, with it off you should see higher number of oscillation in yaw given any disturbance until it settles. Yaw stability of F-5 is inherent to the design and cant be switched off. Meaning after yawing disturbance (for example adverse yaw induced by ailerons on rolling into turn) settles down, yaw stability of F-5 will ensure that the ball will still remain almost centered during turn.

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1 hour ago, Golo said:

OK, but that is for yaw damping, with it off you should see higher number of oscillation in yaw given any disturbance until it settles. Yaw stability of F-5 is inherent to the design and cant be switched off. Meaning after yawing disturbance (for example adverse yaw induced by ailerons on rolling into turn) settles down, yaw stability of F-5 will ensure that the ball will still remain almost centered during turn.

Another way to say it is that there is natural yaw damping inherent to the airframe, and the Yaw Damper artificially increases the damping.  Same for pitch. 

"Subsonic is below Mach 1, supersonic is up to Mach 5. Above Mach 5 is hypersonic. And reentry from space, well, that's like Mach a lot."

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The main problem with the yaw SAS off is that rudder trim isn't available, which means that during single engine ops and/or asymmetric loads, flying the F-5 is more demanding.

 

The -1 states that The aircraft can be safely flown without augmentation throughout the entire flight envelope.  


Edited by bbrz

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22 hours ago, Machalot said:

Another way to say it is that there is natural yaw damping inherent to the airframe, and the Yaw Damper artificially increases the damping.  Same for pitch. 

Yeah, it's called a vertical stabilizer. But you still need some rudder deflection to maintain perfectly coordinated turns. There is no automated system doing that. 

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6 minutes ago, SMH said:

Yeah, it's called a vertical stabilizer. But you still need some rudder deflection to maintain perfectly coordinated turns. There is no automated system doing that. 

This is a question of degree. You keep saying things like "perfectly".  In a sustained turn with nearly neutral ailerons, there can be a lot or very little adverse yaw, depending on the airframe. To you it feels like too little, but you can only get a correct assessment by calculating how much there should be and then measuring and comparing. So far we have nothing concrete to support your assertion. 

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"Subsonic is below Mach 1, supersonic is up to Mach 5. Above Mach 5 is hypersonic. And reentry from space, well, that's like Mach a lot."

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Hmmm after reading through this thread. I have a feeling you guys are feeding a troll. 

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Again, apparently I'm wrong that it should do it and also wrong that it doesn't do it because it does. How can it be both?

So long as I'm wrong, I guess, that's obviously what matters here.

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