jfkaua
Posts: 972
Joined: Tue Aug 31, 2004 7:42 am

What Part Of The Wing Is This..

Mon Sep 06, 2004 1:58 pm

Hey on a flight a notices that a part of the wing constantly moves during descent up and down on the trail edge of the wing close to the cabin as can be seen in this photo..


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Photo © Antoine Ossadzow



the part thats angled down all the way on the left.. I am pretty sure its not a set flap or anything because it moves freely..
 
QantasA332
Posts: 1473
Joined: Sat Dec 13, 2003 5:47 pm

RE: What Part Of The Wing Is This..

Mon Sep 06, 2004 2:04 pm

It's an aileron (on most aircraft, an inboard one like that is the high-speed aileron, with a seperate low-speed, outboard counterpart)...

Cheers,
QantasA332
 
jfkaua
Posts: 972
Joined: Tue Aug 31, 2004 7:42 am

RE: What Part Of The Wing Is This..

Mon Sep 06, 2004 2:12 pm

How exactly is the high speed one controlled? It didn't seem like it was set "on" or at a certain point like a turn but it was just kinda loosley floating there and bouncing up and down on approach...
 
UAL747
Posts: 6725
Joined: Mon Dec 13, 1999 5:42 am

RE: What Part Of The Wing Is This..

Mon Sep 06, 2004 2:57 pm

From what I understand, as the plane reaches a certain speed, the ones with inboard and outboard ailerons, the outboard ailerons lock into position and the plane is completely controlled by the inboard ailerons. The flapping motion you see on approach is the inboard ailerons reacting to the manuevers the pilot is making with the stick. If you look closely, at slower speeds, the outboard and inboard ailerons work together.

Anyway, think about it...balance a pencil or a rod on the top of your finger, it takes more energy to tilt the rod to the left or right if the pressure is being applied closely to the finger the rod is balanced on. Now, move your finger one end of the rod, either left or right, and you will find it takes less energy to tilt the rod. It's all about leverage. When the plane is at cruising speed, using the inboard ailerons gives the pilot a less-sensitive, smoother banking methods.

However, inboard and outboard ailerons are not on all aircraft. In the Boeing line, the 727, 747, 767, and 777 all have inboard and outboard ailerons. (Not sure about the 707). The DC-10, and MD-11 have both as does the L-1011. AFAIK, NONE of the airbus products have inboard ailerons except for the A300/310 you show in your picture.

Hope you can understand what I wrote. It's hard to explain, and it's late, so I'm sure I made absolutely no sense whatsoever.

UAL747

[Edited 2004-09-06 08:00:40]
"Bangkok Tower, United 890 Heavy. Bangkok Tower, United 890 Heavy.....Okay, fine, we'll just turn 190 and Visual Our Way
 
AJ
Posts: 2295
Joined: Wed Nov 03, 1999 3:54 pm

RE: What Part Of The Wing Is This..

Mon Sep 06, 2004 3:40 pm

Interestingly the A300-600R as pictured does not use outboard ailerons at all, same with the A310.
 
Klaus
Posts: 20578
Joined: Wed Jul 11, 2001 7:41 am

RE: What Part Of The Wing Is This..

Mon Sep 06, 2004 10:10 pm

Ual747: AFAIK, NONE of the airbus products have inboard ailerons except for the A300/310 you show in your picture.

The FBW models don´t need it. Sidestick deflection has no direct connection to the position of the control surfaces (except in "direct law" on the ground or in an emergency). Instead, it requests a certain acceleration in the indicated direction which is simply satisfied by a smaller deflection of the outboard ailerons at high speed.

The 777 which basically emulates a conventional mechanical control setup with its FBW system still does have separate high and low-speed ailerons as far as I know.


AJ: Interestingly the A300-600R as pictured does not use outboard ailerons at all, same with the A310.

They should be operational at lower speeds. Maybe you just didn´t happen to recognize any major deflection after takeoff or during approach.
 
707CMF
Posts: 4698
Joined: Thu Mar 14, 2002 5:39 pm

RE: What Part Of The Wing Is This..

Mon Sep 06, 2004 10:29 pm

Thanks for the plug  Smile/happy/getting dizzy

Indeed, the mobile part features on the picture is an inbound aileron.You might noticed, as well from its deflection that the aircraft was already rolling back towards null inclination !

Cheers,

707
 
challengerdan
Posts: 145
Joined: Sat Sep 27, 2003 3:17 pm

RE: What Part Of The Wing Is This..

Wed Sep 08, 2004 1:37 am

Actually, I think the manufacturers were more concerned about wing twisting moment caused by outboard ailerons than smoothness and sensitiveness for the pilots. That explains why a319 and up don't have them. The software keeps the twisting moment within acceptable levels. That rod analogy is good, only you got it backwards: it's not the load needed to input the movement to the rod that they are concerned with, it's the load the rod actually has to withstand. Don't want to get too technical on this, but a low speed aileron makes it possible to keep the structure near the wing tip lighter. On the airbus, the software does that job by keeping aileron movement to a minimum. no idea why Boeing didn't do samething with 777 since it is fly by wire too... maybe it has something to do with the way the back-up or emegency system works...
if your flight goes MX in YUL, I might be called to fix it!
 
MD11Engineer
Posts: 13916
Joined: Sun Oct 26, 2003 5:25 am

RE: What Part Of The Wing Is This..

Wed Sep 08, 2004 3:07 am

Klaus,

The A300-600 and the A310 use so called All Speed Ailerons, which are in the position of the inner ailerons, but no outboard ailerons (just completed a course on the A300-600 a few weeks ago  Wink/being sarcastic )

Jan

[Edited 2004-09-07 20:07:29]
Je Suis Charlie et je suis Ahmet aussi
 
Klaus
Posts: 20578
Joined: Wed Jul 11, 2001 7:41 am

MD11Engineer

Wed Sep 08, 2004 4:06 am

...and I could have noticed it by just looking more closely at the picture above which suffers from an apparent lack of any outboard aileron at all! Damn.  Nuts

I´m beginning to remember some previous thread discussing this special setup... (Systematic thinking is good in principle, but will sometimes fail when dealing with the exceptions...  Wink/being sarcastic)

Wasn´t it a combination with roll spoiler augmentation? If so, does this affect crosswind margins?
 
pilotaydin
Posts: 2099
Joined: Tue Sep 07, 2004 12:30 am

RE: What Part Of The Wing Is This..

Wed Sep 08, 2004 5:44 am

hey guys, i have an old united 744 manual given to me by a captain when i was in school. I read the chapter on flight controls and it said there is an automatic switching between the inboard and outboard use at 235 KIAS.

I dont know where that manual is now, so i can't contribute anymore

take care!

nice to be new to this forum!
The only time there is too much fuel onboard, is when you're on fire!

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