Interesting Questions

[earl1937]

DaveBB:Earl is a very enthusiastic player and a very experienced pilot.I would never wish to debate Earl on best practices when piloting aircraft.And I would love to fly with Earl in my RV.

I have been wanting to make a series of video , mostly on where to look when performing maneuvers, hence the head cam. Here is my first attempt.

http://www.youtube.com/watch?v=ulpdOHcCiNE


 But I do not see anyone telling early how a plane flew or how to fly a plane. I see a technical discussion of aerodynamics about what make planes fly. In this particular case, adverse yaw. A pilot must be taught about adverse yaw so as to know he must apply rudder to compensate for it. Thinking and remembering that a downward aileron causes drag is a good way to remember.

But i have learned that most pilots only have a basic understanding of the physics of flight. Pilots are taught in a way that they understand the basics of physics as is required to best operate an airplane. The diagram on the wiki sight is 100 % correct. But it also does not tell the entire story. It is showing what causes adverse yaw in a steady state roll. There is also adverse yaw immediately when applying aileron Pryor to the roll developing . This is basically do to the downward deflected aileron. But more accurately it is do to the shifting of the lift vs AOA curve due to the increase camber of the wing caused by the downward deflected aileron. This lift curve shift creates more lift & hence more induced drag and  possibly more profile/parasitic drag. Once the roll is steady state, (not a steady state turn but ROLL) then both wings must be producing approximately the same lift or the roll would be increasing or decreasing in RPM. The AOA is greater on one wing vs the other , but the camber is greater on the lower AOA wing so both are creating the same lift. The steady state condition is what the wiki is describing. Also that diagram is very similar to why makes a helicopter auto rotate.

Now notice  this quote from early "Don't know who posted that explanation on Wiki, but it is not quite true". With out any physics explanation of why he thinks it is not true. And when debated Earl simply states i have all this back ground I teach ,I fly and I have written articles.

HiTech

Would love to kick the tires, light the fires and leap into the blue with you sometime! Just to set the record straight, I would refere anyone who is taking exception with me about the discussion which is going on, I refere you to this: http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/
The is the Federal Aviation Agency basic handbook on what the instructor should be teaching his or her student! It is in PDF form, so when you visit and want to view, right click on 1-3, save target as! The PDF will open up and you can view all the different subjects which we have been talking about. Section 3-8 is the one which references effects of the down aileron and its effects.
Any of you can test this for your self: next time you are in a/c in flight, apply a little left or right aileron and see for your self which way the nose moves FIRST! If you apply left aileron, your aircraft nose will move right FIRST, before it begins to bank to the left. The reason the nose moves right to begin with is the drag created by the down aileron, not the additional lift created by the high wing. In this chapter I am referring you to, there is a good diagram of how relative and resultant lift works on the aircraft wing.

[GScholz]

The reason the nose moves right to begin with is the drag created by the down aileron, not the additional lift created by the high wing.

Earl is correct. It has nothing to do with the position of the wing, however it does have something to do with generating more lift. The reason the aileron is generating more drag is exactly because it is producing more lift by changing the curvature of the portion of the wing it covers. Due to inertia the adverse yaw occurs before the roll, and this is more noticeable the heavier the plane is.

[colmbo]

Earl is correct. It has nothing to do with the position of the wing, however it does have something to do with generating more lift. The reason the aileron is generating more drag is exactly because it is producing more lift by changing the curvature of the portion of the wing it covers.

The down moving aileron creates drag because it is creating lift (induced) AND because the aileron is sticking out in the slip stream.  It's rarely just one thing.

[GScholz]

"Sticking out in the slip stream" is what creates lift with the corresponding induced drag. I suppose there is some interference drag involved as well since the aileron no longer is more or less flush with the wing surface.

[earl1937]

"Sticking out in the slip stream" is what creates lift with the corresponding induced drag. I suppose there is some interference drag involved as well since the aileron no longer is more or less flush with the wing surface.

Guys, just apply a little left aileron and you will see the nose move RIGHT first before you start turning left! That should prove to you the aileron creates drag!  That will NOT work in this Aces High game, because it is not programed.

[FLS]

"Sticking out in the slip stream" is what creates lift with the corresponding induced drag. I suppose there is some interference drag involved as well since the aileron no longer is more or less flush with the wing surface.

Lift is created by angle of attack. The angle the relative wind meets the wing. It's the rolling that increases the AOA and provides more lift to the rising wing until it stops rising. There are other things going on but the issue has been the increased lift while rolling.

[GScholz]

So you don't think flaps increase lift... Right... Carry on then. 

[FLS]

Guys, just apply a little left aileron and you will see the nose move RIGHT first before you start turning left! That should prove to you the aileron creates drag!  That will NOT work in this Aces High game, because it is not programed.

Try it in a Ta-152 it's easier to see with the longer wings. It is modeled.

So you don't think flaps increase lift... Right... Carry on then.  

Flaps do many things but lift is always a product of AOA and speed. In any case we're not discussing flaps.

[pembquist]

The AOA is greater on one wing vs the other , but the camber is greater on the lower AOA wing so both are creating the same lift. The steady state condition is what the wiki is describing. Also that diagram is very similar to why makes a helicopter auto rotate.

Thanks for saying steady state roll not turn, now it makes more sense. So viewed from behind in a steady clockwise roll the right wing is at a higher angle of attack and the left at a lower angle of attack so if the ailerons were in trail the plane would stop rolling? (all the other parts of the airplane and wing dihedral etc. ignored.)

[GScholz]

Flaps do many things but lift is always a product of AOA and speed. In any case we're not discussing flaps.

That's just it... Where do you measure AoA? ... The answer is: Relative to the chord line of the wing.



What then happens when you lower an aileron (or a flaps)? You lower the trailing edge of that part of the wing, thus changing the angle of the chord-line of that part of the wing, thus increasing the AoA, thus increasing lift, thus increasing induced drag, thus making the plane yaw towards that wing... Voilą! Adverse yaw!

[Stellaris]

Relative lift always works vertically from the top of the wing. Example: if a wing is 60 feet long, in a 45 degree bank, you have effectively reduces the lifting area by 30 feet,

21 feet  sin(45)=.707

[FLS]

Thanks for saying steady state roll not turn, now it makes more sense. So viewed from behind in a steady clockwise roll the right wing is at a higher angle of attack and the left at a lower angle of attack so if the ailerons were in trail the plane would stop rolling? (all the other parts of the airplane and wing dihedral etc. ignored.)

Clockwise the right wing is descending so it's reversed. Also you generally keep a little aileron to offset the roll from the prop.

That's just it... Where do you measure AoA? ... The answer is: Relative to the cord line of the wing.


What then happens when you lower an aileron (or a flaps)? You lower the trailing edge of that part of the wing, thus changing the angle the cord-line of that part of the wing, thus increasing the AoA, thus increasing lift, thus increasing induced drag, thus making the plane yaw towards that wing... Voilą! Adverse yaw!

As you said, it's the increased AOA that creates more lift. The AOA that counts is relative to the 0 lift AOA. Lowering flaps changes the attitude for the 0 lift AOA. It seems like more lift from flaps, but the result is more lift from greater AOA.

[GScholz]

And it is that added lift that creates more induced drag, not "sticking out in the slip stream"... I could even ask what "slip stream" WTF are you talking about? A slipstream is the wake of an object moving through a fluid.

[pembquist]

Clockwise the right wing is descending so it's reversed. Also you generally keep a little aileron to offset the roll from the prop.

Man, I used to be able to build mechanisms in my head and watch the gears turn and levers move. Now it seems like simple 3d visualizations are beyond my grasp. I'm watching the wing move down and watching the streamlines hit it and yes it IS flatter but 20 seconds ago it looked like it was canted at 60 degrees. Not to over share but the first time I realized I was losing it was when I looked at my mothers car which had a cracked torsion tube arm and realized I could not effortlessly see the motion of the suspension parts, that was 10 years ago its only getting worse.

Anyway leave out the prop, would it stop rolling if the ailerons were not deflected?

[FLS]

M
Anyway leave out the prop, would it stop rolling if the ailerons were not deflected?

Do you stop rolling when you center your stick?