Adverse Yaw

[groundpointsix]

As we roll into a bank, the outboard aileron drops, thus increasing the angle of attack on the outside of the turn and increasing drag, causing the airplane to yaw in the wrong direction. We call this adverse yaw.

However, as we roll into the turn, the angle of attack is also increasing on the inboard wing due to the fact that the relative wind is now coming from underneath the wing. This should increase the drag on the inside and counter the adverse yaw from the outside wing.

BUT, the airplane still momentarilly yaws to the outside. Is this simply because there is more drag from the outside wing than the inside wing? Or am I missing something here?

 

[Crosswind79]

Because for a split second or two the ailerons haven't caused the wings to move.....Not entirely scientific, but it worked for me when I was learning and it made sense for my students.....

 

[siucavflight]

Because for a split second or two the ailerons haven't caused the wings to move.....Not entirely scientific, but it worked for me when I was learning and it made sense for my students.....

Completely inacurate.

An aircraft rolls because one aileron is deflected downward while the other is deflected upward. Lift increases on the wing with the downward-deflected aileron because the deflection effectively increases the camber of that portion of the wing. Conversely, lift decreases on the wing with the upward-deflected aileron since the camber is decreased. The result of this difference in lift is that the wing with more lift rolls upward to create the desired rolling motion.
Unfortunately, drag is also affected by this aileron deflection. More specifically, two types of drag, called induced drag and profile drag, are increased when ailerons are deployed. Induced drag is a form of drag that is induced by any surface that generates lift. The more lift a surface produces the more induced drag it will cause (for a given wingspan and wing area). Thus, the wing on which the aileron is deflected downward to generate more lift also experiences more induced drag than the other wing. Profile drag includes all other forms of drag generated by the wing, primarliy skin friction and pressure drag. This profile drag increases on both wings when the ailerons are deflected, but the increase is equal when the ailerons are deflected by the same amount. However, the induced drag on each side is not equal, and a larger total drag force exists on the wing with the down aileron. This difference in drag creates a yawing motion in the opposite direction of the roll. Since the yaw motion partially counteracts the desired roll motion, we call this effect adverse yaw


I think that this explanation would do your students a lot more justice than making something up like what you are telling them.

 

[Crosswind79]

As long as were talking acuracy, profile drag does not include form drag, interference drag, etc....Thats Parasite drag Numb nuts......

 

[Vik]

Well, a couple of things to consider .. wings are designed to produce lift in one direction only .. UP.

So you can assume that the wing automatically has some angle of attack when it is on the ground, so when the airspeed increases, it produces lift.

So when the outboard aileron goes down, it creates a larger angle of attack. The inboard aileron goes up, and produces "negative lift" but because of the design of the wing, it produces an angle of attack which is not as great as the outboard aileron.

So the aileron drag from the outboard is greater, and causes the plane to yaw opposite to the direction of turn.

I hope that answers your question.

As we roll into a bank, the outboard aileron drops, thus increasing the angle of attack on the outside of the turn and increasing drag, causing the airplane to yaw in the wrong direction. We call this adverse yaw.

However, as we roll into the turn, the angle of attack is also increasing on the inboard wing due to the fact that the relative wind is now coming from underneath the wing. This should increase the drag on the inside and counter the adverse yaw from the outside wing.

BUT, the airplane still momentarilly yaws to the outside. Is this simply because there is more drag from the outside wing than the inside wing? Or am I missing something here?

 

[siucavflight]

Why dont you explain it to me then. I would love for you to tell me the difference. Then I will pick you apart, and send me an e-mail address, and I will send you a copy of my masters degree in aerospace engineering. I dont know why you are defensive, is it because you tell your students that adverse yaw is a result of "for a split second or two the ailerons do not cause the aircraft to roll" And I simply informed you that you were wrong.

 

[Crosswind79]

Congratulations! You have demonstrated that you think you are intellectually superior to someone on this board. You also have mastered a way to beat the auto censor for specific words. The only problem with sitting on your high-horse is that it's a little longer fall to the ground. If you want to contribute here, please be able to disagree without being disagreeable and keep the language to that which would be found in your local newspaper. We'll be looking forward to your contributions three days from now when you get out of the penalty box.

Bye for now.

UAL78
Moderator





I was trying to come up with something that would try and explain it without getting technical.....Anybody can cut & copy word for word explanations - You seem to have a real knack for it. I was just trying to simplify it....And by the way Mr. Engineer, you seemed to leave out the fact that once the ailerons are nuetralized they no longer cause any adverse yaw - Then its the underbanking/overbanking tendency that the pilot must deal with....Did they forget to mention that in aeronautical engineering, or did you go to flyers and get your degree from a cracker jack box???

 

[siucavflight]

No sense trying explain something to the ignorant. You sir are now on ignore. And enjoy your time in the penalty box due to the use of profanity.

 

[Uncle Sparky]

Sounds like Married With Children meets Kelly's Skunkworks!!

 

[braidkid]

Ladddiieesss...calm down... haha...