WANTED: VISUAL GRAPHIC of angles of attack during turns

[tzu]

I'm looking for anyone who has a graphic illustrating the different angles of attack during climbing and descending turns.

NO THEORY - Just the graphic please.

[Adam Oke]

If you have Flight Sim, you could probably do it yourself.

Establish in the climb/decent rate that you want and the angle of bank that you want. Maintain, press the "Print Screen" Button on your keyboard (prnt sc).

Go to your favorite picture program, paste and save. I haven't tried this, so I do not know if it works. Worth a shot.

[Tim]

since im starting vacation today:

i only did it for a climb, you should be able to figure the descent out from this

the verticle axis represents the verticle speed - constant for both wings
the horizontal vector is the forward velocity of each wing - outer wing moving faster
the red vector is the net velocity of the wing - airflow being opposite to this
the gree line is the attitude of the wing - also constant for both wings
the angle between the wing and net velocity is th A of A

this isn't to any sort of scale, just made to be visible

INNER WING.................................................................................................OUTER WING

AoA.jpg (11.89 KiB) Viewed 4039 times

to figure it out for the descent just draw the verticle speed vector pointing down and re-draw the net velocity. keep the wings at the same angle just to make it easy to see the difference.

[mcrit]

Thanks Tim, that's a niffty little picture.

[sstaurus]

Awesome, that does make sense. But, in a descent, the outer wing is still moving faster, it seems like drawing another diagram like yours would show the outer wing still having a greater AoA...? (even though we know it doesn't)

Or most likely I'm missing something

EDIT: nm, I think I got it... just flip those diagrams upside down and it works!

[Tim]

glad to help

[Adam Oke]

Oh wow, I missed the boat on what he/she was asking. Disregard my comment. I'll RTFQ squared next time.

[scopiton]

TIM : the red vector is the net velocity of the wing - airflow being opposite to this

how would you define/explain the net velocity
I'm glad you wrotte that, i've never been able to find a proper explaination to that,
any ref in a book ?
thanks

[Bronco Billy]

Hey Tim,

Nice work on this!

I've had someone telling me the same stuff by pm couple days ago. The thing is with your graph it doesnt really work because you add your green line in without the same variables as your red line so they cant be related like this. I might get dumb with all this thinking and not understand properly, its also plausible .


Bronco

[Tim]

TIM : the red vector is the net velocity of the wing - airflow being opposite to this

how would you define/explain the net velocity
I'm glad you wrotte that, i've never been able to find a proper explaination to that,
any ref in a book ?
thanks

not sure where you would ref it, but its just the way the plane is moving. your climbing and moving forward at the same time. think of walking up a hill. your net velocity is the diagonal line up the hill.

Hey Tim,

Nice work on this!

I've had someone telling me the same stuff by pm couple days ago. The thing is with your graph it doesnt really work because you add your green line in without the same variables as your red line so they cant be related like this. I might get dumb with all this thinking and not understand properly, its also plausible .


Bronco

the green line repsents the wing, and it is not a variable. both wings have the same angle. one is higher relative to the other, but the angle relative to the horizon is the same for both wings.

[tzu]

great tips. Any updates?

[chippy]

Hope this one helps, I find it works great.

[Tim]

thats the exact diagram i had in mind when i drew out that little paint thingy. what text book is it in?

[chippy]

I can't remember where I found it originally, but I made a photocopy of it for future use. I wouldn't mind knowing where it came from.

[loopa]

I really like the diagram method it makes perfect sense; but for some students, as soon as they see vectors and x and y axies they freak out; especially if math and basic physics is a weak subject area... which is normal these days

What I like to get across when teaching that is the application of airspeed versus the path of the relative airflow with respect to the wing.

I say, at 100kts and 0 degrees pitch, this is the representation of the relative airflow. Now, at 55kts, and the SAME PITCH ATTITUDE AS BEFORE, the plane is in an induced descent, hence the angle at which the relative airflow meets the wing has to be greater.

Excellent !

Now, You have an aircraft with wings that are going at 100 kts, and now you have an aircraft with wings going at 80kts. Which wing will for the same pitch attitude have the greater angle of attack ? "The wing with 80kts" says the student.

Awesome, now imagine in a descending turn to the right, the left wing is flying through the air faster than the right wing. Which wing should have the greater angle of attack?

And ZING, it clicks like you wouldn't believe it.

Same application works for climbing turns.

[tzu]

Chippy
That's exactly the diagram I've been looking for. Thanks for the post!

[Check Pilot]

The unfortunate misconception that the wings have different angles of attack in a turn has been around for a long time and it's not the case at all. Think about the relative airflow around the whole aircraft. As long as the airflow is straight on without any yaw occurring, in a turn, as it is in straight flight both wings travel at the same speed relative to the airflow.

The only time the wings would be at different angles of attack would be when a skid or slip is being induced.

[Louis]

Check Pilot: Care to explain the whole "one wing stalls before the other" in coordinated climbing/descending turns in more detail then?
You're going against most of what's been said here so far, enlighten us please. (By the way, that's not meant to sound like sarcasm just to be clear, given text's lack of tone.)

[Tim]

The unfortunate misconception that the wings have different angles of attack in a turn has been around for a long time and it's not the case at all. Think about the relative airflow around the whole aircraft. As long as the airflow is straight on without any yaw occurring, in a turn, as it is in straight flight both wings travel at the same speed relative to the airflow.

The only time the wings would be at different angles of attack would be when a skid or slip is being induced.

this just doesn't make sense to me. how can you have an object travelling in a circular path and say that all parts of the object have the same speed. imagine spining a giant top with something on it to indicate airflow (like a yaw string). all parts of the top would have a straight-on relative airflow, yet the outer part of the top travels quicker. i would like you to go into more detail about this if you could, but the way i see it you have this wrong...i'm open to be educated if i'm the one whos wrong.

[trampbike]

The unfortunate misconception that the wings have different angles of attack in a turn has been around for a long time and it's not the case at all. Think about the relative airflow around the whole aircraft. As long as the airflow is straight on without any yaw occurring, in a turn, as it is in straight flight both wings travel at the same speed relative to the airflow.

The only time the wings would be at different angles of attack would be when a skid or slip is being induced.

You would need TWO rotation axis on the SAME airplane for it to be true: one for each wing... I'm pretty sure the airplane would be in a pretty bad shape after such a bizarre event.

Very nice explanation Loopa. Let's say I'm a slow student, care to also explain the climbing turn to me?

[loopa]

The Climbing Left Turn.

I draw a red line on the white board representing the relative airflow and take out my E6B metal plate and incline it as a normal climb.

This is shown by angle Bravo in the first schematic.

Then by rolling and maintaining a banked attitude to the left, you have inclined the wing by a component of angle Romeo.

Bravo + Romeo = Net Angle of Attack on up going wing

See picture one

Using the same example for the down going wing wing, you have angle bravo during a normal climb, and then with a wing drop, you have a a declining angle "angle Yankee"

Bravo - Yankee = Net Angle of Attack on the down going wing.

Sorry about the pictures my 3d drawing isn't up to par with Photoshop. And Tramp, you're 150% right about needing two axies in that case. But since we only have one axies, the angles have to vary due to their rotation about it.

This was the way that was taught to me; please correct me if I'm wrong.

But if the student is really bright it's really simple. The plane climbs at 700 fpm, the wings are attached to the plane so they are also climbing at 700fpm. As a result our VS is a constant. Since the outer wing is going through more air in order to get to altitude, it has a shallower net velocity. And since the inner wing is going through less air, it has a steeper velocity. Draw a wing and you get the different angles. Just like what Tim said.

[trampbike]

But if the student is really bright it's really simple. The plane climbs at 700 fpm, the wings are attached to the plane so they are also climbing at 700fpm. As a result our VS is a constant. Since the outer wing is going through more air in order to get to altitude, it has a shallower net velocity. And since the inner wing is going through less air, it has a steeper velocity.

Thank. To me, this is the best way to explain it. Might work pretty well with students that are not too visual.

[loopa]

If I say what you quoted, I will have similar diagrams to what Tim drew but also explain why the vectors look different (one being steeper, and one being shallower).


Not sure if you're making fun of me by sarcasm or actually being supportive.


Anyway, best of luck to you

[trampbike]

I was being supportive. No sarcasm at all in what I wrote (and none here either when I say there's no sarcasm!).

[loopa]

Miss communication of text I suppose.


I'm glad it helped.