Olympic A-340
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What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 12:56 am

After looking at some pictures of my favorite airbus planes as well as some 777/767s, I began thinking: what is the purpose (from an aerodynamic perspective) of drooping ailerons?
 
buckfifty
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RE: What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 1:35 am

Drooping ailerons act as additional high lift devices to augment the flap during t/o's and landings. Though from my knowledge, none of the planes you mentioned above have them.

They're usually found on fighter planes or STOL aircraft. One plane I know for sure that had them was the Twin Otter.
 
FDXmech
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RE: What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 2:26 am

In my experience the A300-600 has them.

Also, the MD11 has them, though Fedex deactivated theirs due to reliability issues.
You're only as good as your last departure.
 
gordonsmall
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RE: What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 2:46 am

The A319/20/21 all have drooping ailerons, the ailerons droop 5 degrees when the slats are extended I believe.

Not sure about the bigger Airbus aircraft or any of the Boeings though.

Regards,
Gordon.
Statistically, people who have had the most birthdays tend to live the longest.
 
fritzi
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RE: What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 5:42 am

Just to add what Gordonsmall said:

The A330 and A340 also have drooping ailerons.

 
AJ
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RE: What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 7:41 am

"Though from my knowledge, none of the planes you mentioned above have them."
Both the 767 and 777 have inboard ailerons that droop with trailing edge flap extension.
The reason Boeing gives for drooping the 767 ailerons is to lower the nose attitude on approach for visibility and commonality with the 757's attitude.
 
UAL747
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RE: What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 9:16 am

The 777's outer ailerons also droop FYI.

UAL747
"Bangkok Tower, United 890 Heavy. Bangkok Tower, United 890 Heavy.....Okay, fine, we'll just turn 190 and Visual Our Way
 
buckfifty
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RE: What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 11:40 am

Ah. Learn something new everyday.
 
SAAB340
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RE: What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 11:42 am

Can someone post a picture that displays a good example of this?

Thanks
Paul
 
AJ
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RE: What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 1:13 pm

Paul:

View Large View Medium
Click here for bigger photo!

Photo © Deborah Spragg
View Large View Medium
Click here for bigger photo!

Photo © Wietse de Graaf

 
Slcpilot
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RE: What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 2:10 pm

I think the following picture may be a better example that shows a "drooping" aileron. One can't conclusively make that assumption from this picture; however, since it only shows one aileron and the plane might be in the process of rolling out of a turn....


View Large View Medium
Click here for bigger photo!

Photo © Alejandro Ramos Garduño



An interesting sidenote..... As a kid I remember doing a few space-A flights on a C-5A. It seems they had some wing fatigue issues, and as a result reflexed the ailerons UP six degrees in cruise to reduce the moments on the wing and the associated wing flex. I think most of the C-5As were later re-winged, but I'm not certain...

SLCPilot
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suspen
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RE: What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 4:44 pm

In 1981, C-5As started receiving new alloy wings. The program was complete by 1986.  Smile
Tower: "Cessna xxxx, state your intentions", Cessna: "To become airline pilot"
 
RyDawg82
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RE: What Is The Purpose Of "drooping" Ailerons

Mon Aug 18, 2003 7:54 pm

Hey I had this same post about 2 years ago, some good info on the 767/777 == check it out...

http://airliners.net/discussions/tech_ops/read.main/24822/4/

Ryan
You can take the pup out of Alaska, but you can't take the Alaska out of the pup.
 
Ejazz
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RE: What Is The Purpose Of "drooping" Ailerons

Tue Aug 19, 2003 9:01 am

The B777 has outboard ailerons and inboard flaperons. Both droop when flaps are extended.
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JBirdAV8r
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RE: What Is The Purpose Of "drooping" Ailerons

Wed Aug 20, 2003 9:43 am

Okay, to add another question into the mix...

When I was on a 764 flight I noticed the right inboard aileron deflected a few degrees upward in level flight. Is this AFCS-related? I don't think it would be, since it seemed to stay stationary.
I got my head checked--by a jumbo jet

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