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#12
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" jls" wrote in news:758jd.40492$T_.36816
@bignews4.bellsouth.net: "James Robinson" wrote in message ... Ramapriya wrote: ... why does the banking of wings by the use of ailerons not just roll an aircraft but also produces a turn (yaw)? Simply stated, when an aircraft is in level flight, the lift of the wings works directly against gravity. When an aircraft rolls one direction or the other, the lift of the wings rolls away from vertical, remaining at 90 degrees to the wings. This means only part of the lift works against gravity. The rest causes the aircraft to swing away from straight flight. It is somewhat akin to the effect of banking on a race track. Fair enough. The turn is caused by the horizontal component of lift. Sure, but that still does not explain why the airplane turns. A horizontal component of lift will make the airplane side-slip, not turn. It is the stability (weathervane effect) that makes the airplane turn. Posted Via Usenet.com Premium Usenet Newsgroup Services ---------------------------------------------------------- ** SPEED ** RETENTION ** COMPLETION ** ANONYMITY ** ---------------------------------------------------------- http://www.usenet.com |
#13
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"BTIZ" wrote in message news:K97jd.86842$bk1.136@fed1read05... As to the aileron, think of the relative wind on the wings. With an aileron dropped (looking like a flap), there will be increased drag. Of course the other one goes up, but I don't think the resultant force is equal on both wings. Thus, yaw results. Brian, are you stating that this yaw causes the turn?, actually this is adverse yaw and resists the turn. Come, lets step into my flying laboratory, the Grob 103, and we'll explore that interesting concept called adverse yaw. BT Inside rudder will most definitely produce bank which will produce turn exactly as Brian said it would. There is a difference between adverse and complimentary yaw. Actually, there will be no adverse yaw if inside rudder alone is used to induce complimentary yaw. Only aileron application into a bank with no inside rudder will produce adverse yaw. If complimentary yaw (inside rudder) is used with no aileron, the speed difference between the retreating inside wing and the forward moving outside wing will cause bank, which will be a direct secondary result of the complimentary yaw being produced. In other words, insider rudder will most definitely produce bank as a secondary effect and as such will produce turn...assuming no anti turn control input is present. Dudley Henriques International Fighter Pilots Fellowship for email; take out the trash |
#14
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"Ramapriya" wrote in message om... Where does the turning effect come from? The most basic (maybe too basic) answer is generally this: When you bank, the lift is at an angle, not straight vertical. That angle pushes it the plane to the side as well as up. |
#15
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On Sat, 6 Nov 2004 10:41:12 -0800, "Peter Duniho"
wrote: "Ramapriya" wrote in message . com... Unlike the elevators and rudder that change an aircraft's pitch and yaw with no other secondary effect, why does the banking of wings by the use of ailerons not just roll an aircraft but also produces a turn (yaw)? The simple answer is that, theoretically, the ailerons act exactly as you would think. That is, a turn is not caused by a change in bank. In level flight, the wings are generating 1g of lift, equivalent to the weight of the aircraft and all occupants inside. If this lift vector is rotated by the ailerons then it will point in the direction of the rotation, and therefore force the aircraft to change its direction of flight, and therefore to turn. And there will a corresponding loss of lift against gravity; all simply calculated by geometric functions of sine and cosine. So the aircraft will begin to descend, as it turns. A more complicated answer is that since the "center of lift" is ahead of the "center of gravity", having the lift vector tilted to one side or the other by bank does pull the nose of the airplane around a bit, inducing a turn. If the center of lift actually was ahead of the center of gravity then the aircraft would loop nose-up, so it isn't. They are aligned. But it is the acceleration in the direction of the rotated lift vector which changes the direction of the airflow around the aircraft. So the airfoils at the tail force the airplanes nose to point into the direction of the changing wind. This also changes the direction of the lift vector to the new location, which is actually the same location, and it is known as the center point of the circle the airplane is drawing out in 3-d space. The circle is actually the bottom of a cone, with the cone drawn by the lift vector of the aircraft. The tighter the turn then the flatter the cone. If there is no turn then the cone is not a cone but a flat plane instead. In other words, the aircraft in a turn is flying in a circle, instead of just accelerating sideways and retaining its former forward velocity, which it does not do. The changing wind over the airfoils rotate the aircraft into flying into a circle. An even more complicated answer points out that the ailerons themselves create increased drag on the raised wing and reduced drag on the lowered wing, which creates a yaw opposite in direction to the intended turn. More or less. A lowered aileron has the increased drag, while a raised aileron has less drag. This will pull the nose around opposite from the direction of expected bank. Adverse yaw is the ailerons acting in place of the rudder, and it prevents the aircraft from lining perfectly into the wind. But once the aircraft is banked then the aircraft will turn. The aircraft turns because it is banked. A banked aircraft will not turn if, and only if, the wing is not generating lift. A wing will not generate lift if its angle of attack is so controlled by the horizontal stabilizer. One other note, the aircraft will lose lift and so descend as it banks into a turn. But as it descends, the wings will regain upward airflow and restore the lift lossed. This stops the downward acceleration, with the airplane having reached its terminal velocity. But the lift, and the loads on the wing, have increased just from the aircraft going into a bank; even if adjustments have not been made for level flight. (I think this is ~correct. Pretty sure.) --Mike |
#16
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"The Weiss Family" wrote in message ...
Unlike the elevators and rudder that change an aircraft's pitch and yaw with no other secondary effect, why does the banking of wings by the use of ailerons not just roll an aircraft but also produces a turn (yaw)? Logically, one would expect an aircraft to keep going straight ahead even if the pilot banked the aircraft left or right. Where does the turning effect come from? Is there a website you know of that can teach me such basics, without having to bug you? Cheers, Ramapriya Rudder most definitely adds roll as a secondary effect. In fact, I use rudder to momentarily keep the wings level when I'm changing maps, etc. At low speeds, when the ailerons are not that effective, rudder can be much more effective. As to the aileron, think of the relative wind on the wings. With an aileron dropped (looking like a flap), there will be increased drag. Of course the other one goes up, but I don't think the resultant force is equal on both wings. Thus, yaw results. While it seems intuitive to me, I probably don't have the best explanation, so can anyone else elaborate? Adam N7966L Beech Super III Because when the wing is level, the lift is up. When the wing is banked to the right, the lift is also tilted to the right pulling the plane in the direction. Same for the left. Bryan |
#17
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I was always under the impression that in most light a/c, the dominate
rolling effect from 'inside' rudder is the result of dihedral (or alternatively, sweep back). RC modelers are pretty adept at setting up aircraft for 'pure' yaw from rudder input - no dihedral, symmetrical layout, etc. Or setting up aircraft to bank and turn without ailerons - lots of didedral. Though I'd agree that the "forward motion of the outside wing" explanation accurately predicts the rolling effect from rudder input that occurs on most a/c - which is ok for training purposes. "Dudley Henriques" snip If complimentary yaw (inside rudder) is used with no aileron, the speed difference between the retreating inside wing and the forward moving outside wing will cause bank, which will be a direct secondary result of the complimentary yaw being produced. In other words, insider rudder will most definitely produce bank as a secondary effect and as such will produce turn...assuming no anti turn control input is present. Dudley Henriques International Fighter Pilots Fellowship for email; take out the trash |
#18
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"Maule Driver" wrote in message om... I was always under the impression that in most light a/c, the dominate rolling effect from 'inside' rudder is the result of dihedral (or alternatively, sweep back). RC modelers are pretty adept at setting up aircraft for 'pure' yaw from rudder input - no dihedral, symmetrical layout, etc. Or setting up aircraft to bank and turn without ailerons - lots of didedral. Though I'd agree that the "forward motion of the outside wing" explanation accurately predicts the rolling effect from rudder input that occurs on most a/c - which is ok for training purposes. I would agree with this completely. Dihedral contributes heavily to the lateral stability of the aircraft if sideslip is present to be sure. The prime contribution of dihedral is in the development of a stable rolling moment with sideslip, which is consistent with what most of us are saying. The problem with answering many questions in aerodynamics is that there isn't one single example or answer that will suffice. (Lift is a PRIME example of this. ) Anyone trying to explain lift in a simple sentence will find a slew of missing data soon to follow :-) The problem in aerodynamics is that in much of what is happening, several explanations are in force physically together at one instant in time. The way we look at dihedral in the flight test community is primarily as it's effect on the lateral stability scenario which relates with sideslip present to relative wind, differential in angle of attack, changes in lift raising a windward wing producing stability. I think we're both on the same page, and dealing with the same effect since all of what we're discussing is present in complimentary yaw IF dihedral is present. Now, if we inject an airplane into this equation like a Cessna 195 for example.......... :-)))) Dudley Henriques International Fighter Pilots Fellowship for email; take out the trash |
#19
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(Ramapriya) wrote in message . com...
Hi guys, Unlike the elevators and rudder that change an aircraft's pitch and yaw with no other secondary effect, why does the banking of wings by the use of ailerons not just roll an aircraft but also produces a turn (yaw)? Logically, one would expect an aircraft to keep going straight ahead even if the pilot banked the aircraft left or right. Where does the turning effect come from? Is there a website you know of that can teach me such basics, without having to bug you? Cheers, Ramapriya Alas, Ramapriya, it is far more complex than that! First of all, the rudder causes not only yaw, but by virtue of the yaw accelerating the outside wing and effectively increasing lift, causes bank toward the inside of the turn. The ailerons cause both roll AND yaw...but counterintuitively, the yaw is to the outside of the turn. That is because the creation of lift also creates drag. And when you use the ailerons to bank, you are increasing the lift on the outside wing...and therefore yawing toward the "outside" of the turn. The rudder largely is used to counter that force. And none of that is why an airplane turns. The true cause of the turn is...well, we need to look at an airplane in our mind's eye...picture it in level flight. The force of gravity is offset by the force of lift...generated by the wings. We can say that there is a downward vector...gravity...and an upward vector...lift, which is perpendicular to the airplane's wing. Now, let us bank the airplane. The lift vector is still perpendicular to the airplane's wing, but now it is directed somewhat toward the inside of the bank. And the airplane therefore turns that way...is pulled that way, if you will. Oh, and yes, since the lift vector is directed toward the inside of the turn, the amount of lift to counteract gravity is decreased...and the airplane will descend unless something is done...usually the addition of power or an increase in the angle of attack...increases the antigravity portion of the lift vector. That will either help or totally confuse you. Feel free to email me for a dialog. Jim |
#20
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I strongly suggest that you visit
www.whittsflying.com It will answer pretty much any flying question that you have. I also suggest that you go for a discovery flight - sounds like you are moree than ready Of course, you are also still welcome to ask here. Tony -- Tony Roberts PP-ASEL VFR OTT Night Cessna 172H C-GICE In article , (Ramapriya) wrote: Hi guys, Unlike the elevators and rudder that change an aircraft's pitch and yaw with no other secondary effect, why does the banking of wings by the use of ailerons not just roll an aircraft but also produces a turn (yaw)? Logically, one would expect an aircraft to keep going straight ahead even if the pilot banked the aircraft left or right. Where does the turning effect come from? Is there a website you know of that can teach me such basics, without having to bug you? Cheers, Ramapriya |
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