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do ailerons provide lift?

Old 01-13-2013, 04:05 PM
  #101  
mike31
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Default RE: do ailerons provide lift?

Just for info the down aileron increases drag on that side. Thus the need for rudder input to make what is known as a co-ordinated turn. Normally the addition of power helps with altitude and the elevator in a turn helps maintain altitude as well. While on the subject an arguable issue is elevator affects airspeed while throttle use has to do with altitude. If you want check it for yourself. Establish a constant airspeed and slowly pull back on the elevator. A stall will happen assuming you are not flying so fast only a loop happens. A stall is a function of airspeed. Again, establish a constant airspeed approximately half throttle and add power or decrease power. Watch what happens.
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Old 01-13-2013, 04:07 PM
  #102  
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Default RE: do ailerons provide lift?

I believe I understand your explanation, and that AOA and AOI are different and independant. Nor am I doubting what your saying, so let me pose this question: If a fully-symmetrical airfoil is mounted with 0 degrees of + incidence, where is the lift generated?
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Old 01-13-2013, 05:33 PM
  #103  
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Default RE: do ailerons provide lift?

I believe I understand your explanation, and that AOA and AOI are different and independant. Nor am I doubting what your saying, so let me pose this question: If a fully-symmetrical airfoil is mounted with 0 degrees of + incidence, where is the lift generated?
Ahh, now that isthe question isn't it. The answer is actually fairly simple, although not obvious because it is something that typically can't be seen visually. Here it is.......

Lets use a Yak 54 for example. The wing, tail, and everything is set up at exactly 0 degrees incidence, fully symetrical airfoil....so how does it fly? Quite simply, it needs a possitive angle of attack, so the wing does what it needs to do, and all by itself flies at a slight positive angle. Now, this means that the nose is pointed up slightly all the time. But, not enough to see it from the ground. It doesn't take much of an AoA to get that symmetrical wing to produce lift, especially at a higher speed, so the angle is small enough that it looks perfectly level when it flies past.

If you were to mount that wing with a slight positive angle of incidence, the fuselage would fly level......BUT.....(and here comes the reason we use a 0-0-0 angle on these aerobats).......flip the airplane upside down and it is going to fly different. With the positive angle of incidence, the fuselage might sit level during right side up flight, but inverted it is now going to be pointed nose up quite a bit. This is something we do not want, so if we use 0 degrees incidence, it may fly very slightly nose up all the time, but it will e the same right side up or upside down.

Again, the angle is small enough that we don't see it at high speed, but if you want to visualize it, slowly throttle back and slow the airplane down, and try to maintain altitude. As the airplane slows down, you will hve to bring the nose further and further up to maintain altitude.

Interesting side note regarding this ....a number of years ago there was a company in Kelowna, British Columbia up here in Canada that wanted to imrove the performance of the DeHavilland Beaver. One of the mods they did was put more positive incidence in the wing. This had the result of bringing the nose down in cruise, because the wing still flew at the same angle of attack as before....its smart that way see, it knows what it needs to fly at to keep your butt in the air. The end goal was better visibility for the pilot, and faster cruise speed because there was less drag from the fuselage since it wasn't "dragging its tail" as bad.
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Old 01-13-2013, 05:41 PM
  #104  
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Default RE: do ailerons provide lift?

ORIGINAL: ovationdave

I believe I understand your explanation, and that AOA and AOI are different and independant. Nor am I doubting what your saying, so let me pose this question: If a fully-symmetrical airfoil is mounted with 0 degrees of + incidence, where is the lift generated?
When a wing with a fully-symmetrical airfoil is mounted with 0 degrees AOI the lift is generated when you pull back on the stick and change the neutral AOA to a positive AOA while moving forward into the relative wind. The higher the wing loading the more AOA and or power is required for any given task and vice versa. Now with your wing, horizontal stab, and thrust line all set to a 0 degrees AOI, the aircraft will seek its own AOA to carry a given load. IMO lighter is better for for this very reason as well as many other reasons, but that is just me.

Bob
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Old 01-13-2013, 06:12 PM
  #105  
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Default RE: do ailerons provide lift?

ORIGINAL: ovationdave

I believe I understand your explanation, and that AOA and AOI are different and independant. Nor am I doubting what your saying, so let me pose this question: If a fully-symmetrical airfoil is mounted with 0 degrees of + incidence, where is the lift generated?

Where it always is.

At any speed, the wing assumes the AOA needed to provide the lift you demand with your pilot input trim or elevator position. The wing moves the fuselage to whatever angle the wing and pilot chose. Depending on the incident angle built into the airplane, the fuselage will be forced into an AOA and generate drag depending on it's angle of attack.

If the designer was good, and you're flying the airplane at the speed he assumed when deciding what the wing incidence would be, the fuselage will produce less drag and the entire system will be as efficient as hoped for.
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Old 01-13-2013, 07:36 PM
  #106  
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Default RE: do ailerons provide lift?

ORIGINAL: mike31
......A stall is a function of airspeed.
Sorry, Mike, that is not correct.

A stall is a function of AOA, nothing else.

Reach the critical AOA, beyond which the layers of air detach from the low pressure surface, and the CL goes down dramatically (the wing stalls or quit lifting as it should) and the drag goes sky rocketing.

That happens at a consistent angle, regardless of airspeed.

"Note that the lift equation does not include terms for angle of attack — that is because the mathematical relationship between lift and angle of attack varies greatly between airfoils and is, therefore, not constant. (In contrast, there is a straight-line relationship between lift and dynamic pressure; and between lift and area.) The relationship between the lift coefficient and angle of attack is complex and can only be determined by experimentation or complicated analysis. See the accompanying graph. The graph for section lift coefficient vs. angle of attack follows the same general shape for all airfoils, but the particular numbers will vary. The graph shows an almost linear increase in lift coefficient with increasing angle of attack, up to a maximum point, after which the lift coefficient reduces. The angle at which maximum lift coefficient occurs is the stall angle of the airfoil."


http://en.wikipedia.org/wiki/Lift_coefficient
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Old 01-13-2013, 07:44 PM
  #107  
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Default RE: do ailerons provide lift?

Just for fun, does the fuselage area between the wings add lift?

Bob
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Old 01-13-2013, 09:27 PM
  #108  
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Default RE: do ailerons provide lift?

 
Just for fun, does the fuselage area between the wings add lift?  

Great question. From a design standpoint, that area is considered part of the total wing area, so the answer is yes. 
Flying wings are all wing (obviously). 
A few years ago, there was an F-15 that lost an entire right wing half, yet managed to land safely. Lots of power and AOA is what saved that pilot. Oh, and I believe the lift from the remaining aileron helped. [8D]
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Old 01-14-2013, 12:37 AM
  #109  
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Default RE: do ailerons provide lift?


ORIGINAL: sensei

ORIGINAL: drac1

ORIGINAL: sensei

ORIGINAL: drac1

IMO ailerons will provide lift only if they are part of the airfoil of the wing, the chord would be then from the leading edge of the wing to the trailing edge of the aileron.
If the ailerons are flat with no airfoil profile (as on some sports planes and fun fly's), the chord would then be from the leading edge of the wing to the hinge line as the aileron being parallel top and bottom would provide no lift.

When the ailerons are deflected, they alter the direction of airflow which causes the plane to roll. The reason the plane loses altitude is because the lift from the wing is no longer acting directly upwards but at an angle and their isn't sufficient lift acting upwards to maintain altitude. To turn, elevator must be applied which again, alters the direction of airflow moving the tail of the plane which in turn changes the direction of the plane. To prevent loss of altitude the elevator must be applied between the wings being level and at 90 degrees.
The stab will contribute very little to lift in most cases as the majority of models do not have airfoil sections on the stab. The stab/elevator and fin/rudder are primarily to steer the plane.
It was mentioned in an earlier post that if the model pulls to the canopy or belly in a vertical climb, adjust the ailerons up or down to achieve a straight vertical. This would most likely work, but the correct fix is to adjust down thrust on the engine.
Oh really, go remove an aileron from one side of your wing, then go fly your airplane this way. Now come back and tell us all just how it had no effect on it's flight characteristics, how there was no need for trimming the aileron on the wing that has an aileron of course, thus reducing the LIFT of that wing in order to maintain level flight, or....

Bob
1. What's the sarcasm about? I stated ''IMO'' and i stand by it. Everyone is entitled to their opinion and be part of a reasonable discussion.
2. I didn't say that the ailerons don't affect flight characteristics. You need to read the post, then think about your reply before hitting the OK tab.
3. How can an aileron that is parallel produce lift as there is no difference in air pressure top and bottom? The aileron when deflected changes the AOA which puts air pressure against the surface causing the plane to roll.
The only thing that keeps a flat plan foamy in the air is the AOA, which is attained by the propellor thrust and applying elevator, which again is changing the AOA. Cut the throttle and the plane will fall as there is no air pressure against the wing or air pressure differential to hold it there.
4. That's just being silly saying to remove an aileron and fly.
5. But hey, that's MO and you're the guy at the field who is always right.
Have you ever flown an airplane that shed an aileron or a wing half for that matter? I have, you find out real quick what the absence of wing area does on any part of that wing while flying.

Bob
1. See point 2.
2. No i haven't and it's not on my bucket list. I have no doubt that losing a wing half would adversely affect the planes ability to provide lift.
3. I have never had any bits fall off my aircraft. I build the bits to stay on.
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Old 01-14-2013, 12:43 AM
  #110  
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Default RE: do ailerons provide lift?


ORIGINAL: eddieC

How can an aileron that is parallel produce lift as there is no difference in air pressure top and bottom?

You're assuming there's no difference in air pressure. Can you prove that assumption?

Lets not forget that all control surfaces work on Bernuli's principle.
Bernoulli isn't the only principle at work. Remember AOA? Equal and opposite reaction from deflecting the surface, and I believe it has more effect than Bernoulli. Look at a 3D airplane that basically never stalls (as long as the engine is running). It's almost all AOA, going from a prop hang and transitioning to forward flight.

IMO Mr. Bernoulli gets way too much credit.

No. Can you prove that there is a difference in air pressure?

Doesn't the difference in air speed over the surfaces create the low pressure zone which creates lift?
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Old 01-14-2013, 12:44 AM
  #111  
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Default RE: do ailerons provide lift?


ORIGINAL: eddieC

Just for fun, does the fuselage area between the wings add lift? [img][/img]

Great question. From a design standpoint, that area is considered part of the total wing area, so the answer is yes.
Flying wings are all wing (obviously).
A few years ago, there was an F-15 that lost an entire right wing half, yet managed to land safely. Lots of power and AOA is what saved that pilot. Oh, and I believe the lift from the remaining aileron helped. [8D]
Hmm. I think i will stay away from that one.
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Old 01-14-2013, 01:52 AM
  #112  
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Default RE: do ailerons provide lift?

No. Can you prove that there is a difference in air pressure? 

Doesn't the difference in air speed over the surfaces create the low pressure zone which creates lift? 

Let's not reinvent the wheel here, folks. This thread is getting carried away with suppositions while ignoring basic facts. 

Fact: the designers and engineers considers the ailerons as part of the wing area. 
They don't do this to make their job simple. They do it because that's how it actually works. To propose that lift ends at the leading edge of the aileron because it 'doesn't have an airfoil' is, well, laughable. Sorry. The air flows above and below the aileron like it does the rest of the wing, of which it is a part.  Isn't it enough that aeronautical engineers have always used the entire wing, including ailerons, when computing wing area and total lift? Can you not put some faith in what the experts have assumed for over a hundred years? I'm frankly amazed at some of the off-base assumptions being defended. 
Those same engineers compute the wing chord including the ailerons for total lift. Believe it, google or wiki will support it if you don't have a book on aerodynamics handy. I have numerous full-scale manuals, from C-150s to jets, and each one has wing measurements that include the ailerons, fuselage, and tip tanks when installed, for total wing area. 

It's basic facts, folks. I trust it and urge you to do so also. 
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Old 01-14-2013, 02:20 AM
  #113  
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Default RE: do ailerons provide lift?

Okay armchair aerodynamicists, ponder this:
Bernoulli says the air molecules (say molecule A and B) separate at the leading edge, with A going over the top and B going under. Molecule A going over the top of the airfoil accelerates, creating a low pressure which 'pulls' the airfoil up (lift). The assumption was molecule A and B met back up at the trailing edge. What makes them mate back up magically? Nothing, because they don't. It wasn't until the early 80's when researchers at the University of North Dakota proved they don't match up magically. This slightly changed and diluted the Bernoulli effect and improved accuracy of aerodynamic computations. 

So the experts are still testing and learning. I seriously doubt they'll discover lift suddenly ceases at the aileron.  
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Old 01-14-2013, 03:57 AM
  #114  
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Default RE: do ailerons provide lift?

This thread has gone way beyond the level that would keep it in a "Beginners" forum. The question has been asked and answered. What we have happening now is a contest to see how smart folks can be by being one-up on the other guy.

I could have locked it down, but presume you guys want to continue with the banter so I moved it here, to the Aerodynamics Forum, instead.

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Old 01-14-2013, 04:05 AM
  #115  
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Default RE: do ailerons provide lift?

Thanks for the info........
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Old 01-14-2013, 04:15 AM
  #116  
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Default RE: do ailerons provide lift?


ORIGINAL: Lnewqban

ORIGINAL: mike31
......A stall is a function of airspeed.
Sorry, Mike, that is not correct.

A stall is a function of AOA, nothing else.

Reach the critical AOA, beyond which the layers of air detach from the low pressure surface, and the CL goes down dramatically (the wing stalls or quit lifting as it should) and the drag goes sky rocketing.

That happens at a consistent angle, regardless of airspeed.

''Note that the lift equation does not include terms for angle of attack — that is because the mathematical relationship between lift and angle of attack varies greatly between airfoils and is, therefore, not constant. (In contrast, there is a straight-line relationship between lift and dynamic pressure; and between lift and area.) The relationship between the lift coefficient and angle of attack is complex and can only be determined by experimentation or complicated analysis. See the accompanying graph. The graph for section lift coefficient vs. angle of attack follows the same general shape for all airfoils, but the particular numbers will vary. The graph shows an almost linear increase in lift coefficient with increasing angle of attack, up to a maximum point, after which the lift coefficient reduces. The angle at which maximum lift coefficient occurs is the stall angle of the airfoil.''


http://en.wikipedia.org/wiki/Lift_coefficient
Correct. The plane can stall at high speed if too much elevator is applied, resulting in dropping a wing or even a snap roll. Many pilots when experiencing this, blame the radio system for loss of signal, when in reality the plane has stalled.
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Old 01-14-2013, 04:35 AM
  #117  
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Default RE: do ailerons provide lift?


ORIGINAL: drac1


ORIGINAL: sensei

ORIGINAL: drac1

ORIGINAL: sensei

ORIGINAL: drac1

IMO ailerons will provide lift only if they are part of the airfoil of the wing, the chord would be then from the leading edge of the wing to the trailing edge of the aileron.
If the ailerons are flat with no airfoil profile (as on some sports planes and fun fly's), the chord would then be from the leading edge of the wing to the hinge line as the aileron being parallel top and bottom would provide no lift.

When the ailerons are deflected, they alter the direction of airflow which causes the plane to roll. The reason the plane loses altitude is because the lift from the wing is no longer acting directly upwards but at an angle and their isn't sufficient lift acting upwards to maintain altitude. To turn, elevator must be applied which again, alters the direction of airflow moving the tail of the plane which in turn changes the direction of the plane. To prevent loss of altitude the elevator must be applied between the wings being level and at 90 degrees.
The stab will contribute very little to lift in most cases as the majority of models do not have airfoil sections on the stab. The stab/elevator and fin/rudder are primarily to steer the plane.
It was mentioned in an earlier post that if the model pulls to the canopy or belly in a vertical climb, adjust the ailerons up or down to achieve a straight vertical. This would most likely work, but the correct fix is to adjust down thrust on the engine.
Oh really, go remove an aileron from one side of your wing, then go fly your airplane this way. Now come back and tell us all just how it had no effect on it's flight characteristics, how there was no need for trimming the aileron on the wing that has an aileron of course, thus reducing the LIFT of that wing in order to maintain level flight, or....

Bob
1. What's the sarcasm about? I stated ''IMO'' and i stand by it. Everyone is entitled to their opinion and be part of a reasonable discussion.
2. I didn't say that the ailerons don't affect flight characteristics. You need to read the post, then think about your reply before hitting the OK tab.
3. How can an aileron that is parallel produce lift as there is no difference in air pressure top and bottom? The aileron when deflected changes the AOA which puts air pressure against the surface causing the plane to roll.
The only thing that keeps a flat plan foamy in the air is the AOA, which is attained by the propellor thrust and applying elevator, which again is changing the AOA. Cut the throttle and the plane will fall as there is no air pressure against the wing or air pressure differential to hold it there.
4. That's just being silly saying to remove an aileron and fly.
5. But hey, that's MO and you're the guy at the field who is always right.
Have you ever flown an airplane that shed an aileron or a wing half for that matter? I have, you find out real quick what the absence of wing area does on any part of that wing while flying.

Bob
1. See point 2.
2. No i haven't and it's not on my bucket list. I have no doubt that losing a wing half would adversely affect the planes ability to provide lift.
3. I have never had any bits fall off my aircraft. I build the bits to stay on.
IMO ailerons will provide lift only if they are part of the airfoil of the wing, the chord would be then from the leading edge of the wing to the trailing edge of the aileron.
If the ailerons are flat with no airfoil profile (as on some sports planes and fun fly's), the chord would then be from the leading edge of the wing to the hinge line as the aileron being parallel top and bottom would provide no lift.


2. I didn't say that the ailerons don't affect flight characteristics. Sure you did, your stating the ailerons provide no lift if they are flat, if that is true losing one aileron would not affect the flight characteristics now would it, you would not have a need to push the opposite wing down with the remaining non load carrying aileron for level flight.

2. No I haven't and it's not on my bucket list. I have no doubt that losing a wing half would adversely affect the planes ability to provide lift. Losing an aileron also adversely affects the planes ability to provide lift.

3. I have never had any bits fall off my aircraft. I build the bits to stay on. If you fly long enough or hard enough you will. I noticed all your profile pictures are ARFs. Let me tell you, parts do fall off of ARFs that we assemble at times, it even happens on Comp ARFs like the one in your profile pictures. One of my Comp ARF 3.3 Yaks shed the major portion of one wing in the third quarter of a roller at a show one day, now I was able to get the plane down without harming anyone or destroying it and Andreas was kind enough to send me a new wing, but it does happen…


Bob
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Old 01-14-2013, 04:41 AM
  #118  
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Default RE: do ailerons provide lift?

ORIGINAL: eddieC

Just for fun, does the fuselage area between the wings add lift? [img][/img]

Great question. From a design standpoint, that area is considered part of the total wing area, so the answer is yes.
Flying wings are all wing (obviously).
A few years ago, there was an F-15 that lost an entire right wing half, yet managed to land safely. Lots of power and AOA is what saved that pilot. Oh, and I believe the lift from the remaining aileron helped. [8D]
Absolutely yes!

Bob
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Old 01-14-2013, 06:47 AM
  #119  
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Default RE: do ailerons provide lift?

I still stand by my take that in a neutral position, flat ailerons do not add any more lift compared to a wing of equal chord. Of course different wing designs may produce different Reynolds number, so lets take a 4 Star 60 design.
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Old 01-14-2013, 07:10 AM
  #120  
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Default RE: do ailerons provide lift?


ORIGINAL: CGRetired
I could have locked it down, but presume you guys want to continue with the banter so I moved it here, to the Aerodynamics Forum, instead.
Thanks for letting us run wild, CGRetired !!!
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Old 01-14-2013, 07:10 AM
  #121  
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Default RE: do ailerons provide lift?

If your wings don't have washout built in, say a ducted fan jet (F-86) Set the ailerons so the trailing edge is slightly up when in neutral stick. Plane will have less tendency to tip stall on landing
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Old 01-14-2013, 08:21 AM
  #122  
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Default RE: do ailerons provide lift?


ORIGINAL: eddieC

Okay armchair aerodynamicists, ponder this:
Bernoulli says the air molecules (say molecule A and B) separate at the leading edge........
Poor Daniel Bernoulli never knew about an airfoil or that heavy things would ever fly.

In 1738, he published his principle about conservation of energy in a fluid being forced to move inside a pipe.
According to his experiments, the sum of kinetic energy and potential energy remain constant in ideal conditions of perfect heat insulation and lack of friction and turbulence.
Those conditions are far from what happens around a real wing; let alone what happens at speeds around and above the speed of sound.

We are the ones confusing ourselves by trying to explain the complex phenomena of flight using that simple principle.

Check this interesting link:

http://www.grc.nasa.gov/WWW/K-12/airplane/guided.htm
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Old 01-14-2013, 08:35 AM
  #123  
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Default RE: do ailerons provide lift?

Air Planes fly because of Angle of Attack ... Period.  Helio-copters fly for only one reason.
They are so UGLY the ground repels them.
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Old 01-14-2013, 08:53 AM
  #124  
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Default RE: do ailerons provide lift?

Since the discussion isn't dead, thanks again for the insight on AOA. The "the wing does what it needs to" comment was kind of what I was thinking, but the more I thought about it, it makes sense since any object finds its natural path while air is passing around it. Its funny but what came to mind is the scene in "The Worlds Fastest Indian" when he puts a toothpick in the cigar and blows over it........

~Dave
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Old 01-14-2013, 10:47 AM
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Default RE: do ailerons provide lift?


ORIGINAL: sensei
IMO ailerons will provide lift only if they are part of the airfoil of the wing, the chord would be then from the leading edge of the wing to the trailing edge of the aileron.
If the ailerons are flat with no airfoil profile (as on some sports planes and fun fly's), the chord would then be from the leading edge of the wing to the hinge line as the aileron being parallel top and bottom would provide no lift.

Can't think of many airplanes where the ailerons aren't part of the wing's airfoil, but a couple come to mind. The Stuka and the JU52 both fit the description.

The ailerons on those birds contribute lift and drag.

And to the point of this discussion, their area is included in the area of the wing by most AEs when talking about the simpler aspects of the airplanes. Can you think of any outside part of any airplane doesn't contribute to drag and can't provide lift?
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