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AmericanAirFan
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Turning Inflight On An MD-80.

Sat Jul 17, 2004 2:32 am

Most recently I went on an MD-80 and sat behind the wign and I noticed when we turned there was no arelons input on either wing was that the rudder that turned it instead of arelons and rudder? and also on a sharp turn we use arelons and what seamed to be the flaps and there was no hydraulic sound of the flaps moving but the moved and when we leveled out again the flap went up. Can someone explain?

Thanks

-AmericanAirFan
"American 1881 Cleared For Takeoff One Seven Left"
 
HaveBlue
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 2:41 am

Generally speaking, the outer wing 'normal' ailerons are only used during slow speed flight. At cruise speed there are high speed ailerons, which can look a bit like a flap. They are about mid way down the wing, usually a square or rectangular flap like device but in reality just an aileron. Alternately or in unison, a bank can be accomplished by using lift dumpers on one wing. Pretty sure they are just spoilers, but used with a limited deflection, unlike on roll out after landing.

None of them turn on just rudder alone. On smaller aircraft simple ailerons at the end of the wing are used, but in these bigger ones it just is a little more complex.
 
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Starlionblue
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 2:42 am

The ailerons need to move very very little at high speeds so you probably did not notice. In sharp turns the spoilers/airbrakes/lift dumpers on the inward wing (relative to the turn) rise to help dump the wing down. This is pretty much standard on jets.


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AmericanAirFan
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 2:50 am

Im talking on an MD-80 there is so part like a triangle that juts out half way down the wing.
"American 1881 Cleared For Takeoff One Seven Left"
 
dl757md
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 2:57 am

Generally speaking, the outer wing 'normal' ailerons are only used during slow speed flight. At cruise speed there are high speed ailerons, which can look a bit like a flap. They are about mid way down the wing, usually a square or rectangular flap like device but in reality just an aileron.

The Md-80 series does not have high speed ailerons. There is just one aileron per wing located at the outer trailing edge of each wing. They have control tabs that "fly" the aileron to the desired position. As Starlionblue said there is very little aileron movement at highspeed and it could have gone undetected.

The flaps do not assist in roll control. What you noticed on the inboard upper surface of the wing were the flight spoilers. They work in conjunction with the ailerons for roll control. They deploy only on the side of the wing that drops and can extend up to 60 deg in this mode.

Generally rudder input is not used for turns on transport category aircraft.
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AmericanAirFan
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 3:02 am

No im sure it was the flaps the quietly extended down not the airbrakes which extend up.
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dl757md
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 3:13 am

It is required on transport aircraft that the flaps are not allowed to deploy independently from side to side. This condition is called flap asymmetry and is a very serious condition that can cause an unrecoverable roll. If the flaps were used to aid turning as you have concluded they would have had to deploy independently and cause a flap asymmetry which is not a normal situation.

One question. Was the part you are talking about located on the trailing edge or leading edge of the wing?
757 Most beautiful airliner in the sky!
 
air2gxs
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 3:14 am

Flaps cannot (normally) extend on one wing alone, thus they can't assist in turning the aircraft. Ailerons roll the aircraft with assistance from the spoilers when necessary. You did not see flaps, especially in cruise flight.

There is a chance that if this was landing, that the flaps were deployed at some time only to be retracted again due to some change in landing plan. Seen that a few times.

And please watch grammar. Your posts are hard to read.
 
AmericanAirFan
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 3:21 am

It was trailing edge no leading edge.
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AmericanAirFan
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 3:24 am

Also sorry to post another one again I noticed you said it was prior to landing and change in landing plans not it wasnt that cause note I was on the plane and we were about 300 miles from our destination.
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dl757md
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 3:30 am

Sorry AmericanAirFan, The information I have provided is paraphrased from the Delta Md-88 AMM. Unless there is a huge difference in the control systems of the DL Md-88 and the Md-80 you flew on, I can't explain what you saw. BTW Delta's Dc-9, Md-88, and Md-90 all used this same basic control system so I tend to believe the plane you flew on works the same way.

Regards
Dl757md
757 Most beautiful airliner in the sky!
 
AmericanAirFan
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 3:33 am

Thanks for the help  Smile/happy/getting dizzy

-AmericanAirFan
"American 1881 Cleared For Takeoff One Seven Left"
 
avioniker
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 3:49 am

I wonder if you're confusing the control tab on the aileron with the aileron itself and thinking the aileron is a flap???
The ailerons on the MD80 aircraft are not powered at the control surface and, as Dl757md stated, the aileron is actually flown or deflected by the control tab.
If the pilot wants to turn right the right aileron must go up. Depending on the speed of the plane it may not be very much at all. Typically less than one inch at 300+ knots.
To do this the control tab will move down in response to cable inputs from the control wheel or aileron servo actuator .
The downward movement of the control tab alters the aerodynamics of the aileron causing it to deflect up and ultimately causing the wing to go down, turning the plane to the right.
That's the short story, but it's the true story. You didn't see the flaps deflecting to turn the aircraft. (At least not without a major writeup going into the logbook and a major argument between the pilot and the maintenance people)
 Smile/happy/getting dizzy
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Bruce
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 3:56 am

I shot a picture on a turn in an MD80. You can barely tell. plus the flap is not "cleaned up" yet i don't think. although in this picture we are at a pretty slow speed, less than 250kts.


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AmericanAirFan
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 4:03 am

I am sure of all the stuff I saw on my flight i am 1,000,000,000,000,000,000,000% sure.

AmericanAirFan
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avioniker
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 4:22 am

Well, since 100% is the max available in that regard and I've been flying and fixing DC9's for over 30 years, I'll stick with my comments as 99 and 44/100ths% pure
 Smile/happy/getting dizzy


 Smile/happy/getting dizzy
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
dl757md
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 4:28 am

AmericanAirFan

Could you search the Md-80 series photos on A.net, specifically those of the carrier you flew, and try to point out the "part like a triangle that jutts out half way down the wing"?

No one is questioning what you saw. It's just that it doesn't jive with how Md-80 roll control works. There has to be an explanation other than the flaps augmenting roll control. This just can't happen. Believe me.

Regards
Dl757md

[Edited 2004-07-16 21:29:16]
757 Most beautiful airliner in the sky!
 
avioniker
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 5:13 am

The triangular shaped part is probably the lifeline tie-down point
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
AmericanAirFan
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 7:10 am

Im talking on an MD-80 there is so part like a triangle that juts out half way down the wing. I wrote that I messed up when I wrote so part I ment no part. Sorry about that. My mistake.

-AmericanAirFan
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air2gxs
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 7:18 am

I assure you, you did not see flaps at cruise altitude and speed. Flaps do not aid in turning. Ailerons turn the aircraft with the help of spoilers. If the flaps were to move independent of each other (left to right) they would stop functioning as soon as the asymmetry is sensed. Thus they offer no roll component to the aircraft.


Find a picture. Pictures are worth a thousand words, especially since you can't put a coherent sentence together.
 
AmericanAirFan
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 7:48 am

Well I seacrhed for pictures I give up but I know what I saw.

-AmericanAirFan

 Smile/happy/getting dizzy
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avioniker
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 8:00 am

You must remember that proper drug timing is critical to what you see or don't on an aircraft flight.
Without the aircraft the timing isn't so crucial to the vision...
 Smile/happy/getting dizzy
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
Silver1SWA
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RE: Turning Inflight On An MD-80.

Sat Jul 17, 2004 9:40 am

*Flaps at cruise altitude/speeds likely = disaster.
*asymmetric flap/slat deployment would result in a catastrophe like the AA DC-10 in Chicago back in 1979 (Flt. 191).
*Flaps CANNOT physically move up. If you saw a mechanism move up, I guarantee it was not the a flap. Flaps when in the "up" position retract into the wing. Never do they rotate on a hinge upward so that the surface rises above the wing.
*What the heck were you doing in a steep turn during cruise anyway?!
Usually during approach phase, turns can be somewhat steeper and control inputs by the pilots can be somewhat more drastic causing high enough control inputs for the airbrakes/spoilers to deploy on the inside wing (as mentioned above). As far as I know, this does not normally happen during cruise flight unless severe turbulence I guess.
*Don't always be so convinced what you remember seeing, was actually indeed what you saw, especially when you don't know a whole lot about the technical workings of the aircraft you were on. I can assume, based on your original question, that at the time of the flight, you did not have extensive knowledge of such things. The human brain can be kind of funny when it comes to detail and memories. I wouldn't argue with people here that are explaining to you what it was you likely saw based on their extensive knowledge and experience with the very aircraft you were on.
*So in conclusion, I'd have to say, you did not see what you think you saw.
Sorry.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
AmericanAirFan
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RE: Turning Inflight On An MD-80.

Tue Jul 20, 2004 6:36 am

Well hehe one slight dteail we were through 10,000 ft and descending and thats where I saw it but I know it extended with no noise on the turn going probably about 230 knots.

-American Air Fan
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cdfmxtech
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RE: Turning Inflight On An MD-80.

Tue Jul 20, 2004 12:58 pm

Is it possible that since the aileron and are adjacent to one another, the ailerons moving up could have looked like the flaps moving down?
 
PHLapproach
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RE: Turning Inflight On An MD-80.

Thu Jul 22, 2004 2:57 am

I think I know exactly what hes talking about. You say it was on the trailing edge and it went up?
 
AmericanAirFan
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RE: Turning Inflight On An MD-80.

Thu Jul 22, 2004 8:22 am

No it went down.

_AmericanAirFan

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Silver1SWA
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RE: Turning Inflight On An MD-80.

Thu Jul 22, 2004 11:23 am

Theoretically, if the flaps were assisting in a turn, two things would have to happen:

1. For a typical, clean turn, the flaps would have to act like ailerons as one flap would go down while on the other wing, they would go up. Problem is, flaps don't move up therefore this is impossible.

OR

2. Somehow the flaps on one side manage to move down while on the other wing, the flaps stay in the retracted position. This would most likely only happen if some sort of malfunction occurred and would be very ugly.

Again, theoretically, if you saw FLAPS aiding in a turn by seeing the flaps move down on your side of the plane AND ailerons were not being used to control the aircraft, then that would mean:
a. You were sitting on the outside of the turn. (If you were on the inside of the turn and saw flaps go down, the flaps had NOTHING to do with the turn.)
b. The flaps on that side would have to retract in order for the turn to terminate.
However, the plane cannot roll out of the turn unless the situation is reversed and the flaps on the other side extended. These simply are not conventional ways in which to control an aircraft. I'm not even sure the crew can extend flaps on one wing at a time. In order to coordinate such a maneuver, they would need that control.

You likely saw the pilots extend the flaps (together) during a turn, which is normal. For whatever reason, they may have retracted the flaps minutes later to alter their configuration for the approach until closer to the airport. Whatever it was, I do not think it had anything to do with the turn.
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SlamClick
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RE: Turning Inflight On An MD-80.

Thu Jul 22, 2004 11:49 am

There are planes out there with "flaperons" but I'm not aware of any jets that have them, and certainly not the MD-80.

What the MD does have is a spoiler mixer that gives differential flight spoiler when spoilers are in use and roll is called for. The way it works is this: If you have partial spoilers extended, and roll into a turn, the spoiler on the inside wing (right if you are turning right) will go up, slightly and the one on the outside wing will retract slightly. This has the effect of killing some lift on the inside wing, tending to lower it, and increasing the lift on the outside wing, assisting with banking it. At full spoiler deflection the inside wing spoiler cannot extend any further, but the outside one will still retract a little bit.

* * *


The thread-starter is confusing and the description is not getting any clearer with additional explanation. Perhaps it is time to start over by posing the entire question with no typos and no wrong words.

Could the "triangle thing" be a reference to the flap hinge under the wing trailing edge?

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fspilot747
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RE: Turning Inflight On An MD-80.

Thu Jul 22, 2004 2:01 pm

"Perhaps it is time to start over by posing the entire question with no typos and no wrong words."

..and commas, too. I can barely understand the question.
 
AmericanAirFan
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RE: Turning Inflight On An MD-80.

Fri Jul 23, 2004 2:18 pm

Silver1SWA thanks for your post it make sense and I think that's what happened but how comes when the stuck out there was no hydraulic noise they silently went down then back.

-AmericanAirFan

(sorry about my sloppy typeing im only 13 and not very good in language arts  Big grin)
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FBU 4EVER!
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RE: Turning Inflight On An MD-80.

Sat Jul 24, 2004 5:08 pm

As has been already mentioned,the DC-9/MD-80/90 ailerons are not hydraulically operated.Operated by control tabs by old fashioned steel wires from the control wheel. A control wheel deflection of more than 5 degrees from neutral/wings level will operate the outboard flight spoiler panels on the downward moving wing to aid roll rate and response.

These planes are more or less "handbuilt" and as such are not always "true and square",necessitating some aileron and rudder trim at all times to fly straight and level. The "trailing-edge up" aileron will give the impression of the flaps having been extended somewhat but it is just an optical illusion.Maybe this is what was observed by the poster of this topic?
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