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#1
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A very basic question
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 |
#2
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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 |
#3
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"Ramapriya" wrote in message om... Is there a website you know of that can teach me such basics, without having to bug you? http://www.av8n.com/how/ |
#4
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#5
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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 |
#6
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very basic answer..
the lift component, vertical and perpendicular to the wings, in a bank is now pointed off to one side of straight up (relative to earth), there are now two components to the lift vector, horizontal and vertical, the vertical lift assists in maintaining altitude, the horizontal component works the turning tendency. That is why in a steep turn, more elevator back pressure is required. You have reduced the vertical component of lift to maintain altitude by giving some of the lift to the horizontal component. You need to increase the AOA on the wings to make more lift, to maintain the required amount of vertical component to maintain the altitude. again, a very basic answer.. step into the flying laboratory for further exploration of this concept BT "Ramapriya" wrote in message om... 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 |
#7
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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. |
#8
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"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. |
#9
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The turn occurs because as you roll into bank, the lift vector now
has a horizontal component which will pull you in the direction of the bank. Think of a string suspending the wing straight up (the lift vector for level flight). Now think of the string being pulled sideways slightly as well as up. This will pull the aircaft in the direction of the pull... or lift vector... which now has a horizontal component. The rudder is used to coordinate the turn only. You could fly along level with a slight bank angle with no turn (aka a "slip") if you applied opposite rudder... enough to counteract the horisontal lift component. This will only work for a limited bank angle however. 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 |
#10
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"Ramapriya" wrote in message
om... 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. 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. 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. In reality, the ailerons and rudder are BOTH very necessary to accomplish an efficient turn. Either can be used by themselves to change aircraft heading, but neither is very effective alone in most airplanes. As far as the elevator and rudder having "no other secondary effect", that's not true. Pretty much every control on an airplane has a secondary effect. Use of rudder will induce roll, for example, while use of the elevator can induce yaw (mostly due to propeller effects). [...] Is there a website you know of that can teach me such basics, without having to bug you? There are many. The one already provided by Stan's reply is one of my favorites. There are also several good books on the topic, including the FAA's own flight training manuals (available for download from their web site somewhere, but I don't have a link handy) and a book called "Aerodynamics for Naval Aviators". Pete |
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