bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

MD80 Flap Sections, How Are They Extended/stowed?

Tue Apr 26, 2005 1:08 pm

Hi everyone. I have a question that is hard to explain, I'll try to do my best.


The flaps of the MD80s seem to have two sections as these pictures show:


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Photo © Niksa Radicevic - CroSpotterTeam
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Photo © Dion Fuchs



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Photo © ChW - Aviapix Worldwide



They look to me as if each section were on a different sweep angle of the wing, the inboard section being at a lower wing sweep angle, and the outboard at a higher one. If this is true, I don't see how the flap sections will go to the up position without interfering with each other. The flap hinges appear to be not colineal, and if so I don't see how the flap sections can be joined by that riveted patch and still go up and down together. Does anyone know what I'm missing here?

If it is not clear, please let me know and I'll try to do a drawing. Thanks in advance!

regards
Alfredo
 
Dalmd88
Posts: 2448
Joined: Fri Jul 28, 2000 3:19 am

RE: MD80 Flap Sections, How Are They Extended/stowed?

Tue Apr 26, 2005 3:58 pm

The panel between the two sections isn't riveted to either flap. Internally it has a hinge that allows for the movement. The panels are screwed to the hinge.
 
miamiair
Posts: 4249
Joined: Thu Jul 15, 2004 9:42 pm

RE: MD80 Flap Sections, How Are They Extended/stowed?

Wed Apr 27, 2005 1:42 am

The flaps are hinged, as you can see in the Adiratic MD-80 picture. The vanes are attached to the flaps themselves. The MD-80 has inboard and outboard flap sections as the DC-9s only had one whole section. They are set to two different geometric hinge-lines (sweep).
Molon Labe - Proud member of SMASH
 
bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

RE: MD80 Flap Sections, How Are They Extended/stowed?

Fri Apr 29, 2005 8:44 am

Hi, thanks for the responses. It's clear how the rivet band acts as a hinge for both sections. My question was of a geometrical nature, rather than structural. When the flaps are in the down position they are still joined by the rivet panel, and they are angled due to the different wing sweep they belong to. When they are retracted, the tips should interfere with each other not allowing them to go up, because the inboard and outboard sections are facing each other slightly, due to the wing sweep change.

I saw several more photos and understood the following: Flaps don't simply rotate on a wing hinge, but they displace themselves out as well. What happens is that to avoid this flap tip interference when retacting the base of the flap separates as the flaps go up, and this is permitted by the flap assembly movement, which is different than a simple hinge. Here are some pictures:

Extended Flap bases joined

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Photo © Andrea Nolano
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Photo © Paavo Tihverainen



Retracted Flap bases separated

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Photo © Erik Lundgren
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Photo © Koen Duijnmayer



In this way the flaps don't interfere with each other when goung to the up position. Also, when going down they don't generate a gap between the flap sections, because of the rivet panel joining them which covers the flap base gap. That's what I understood from the pictures, I may be wrong.

It is really hard to explain these things through writing, sorry if I have not been clear. These pictures I found helped me get a picture of the movement, thanks for your input.

Regards
Alfredo
 
NKP S2
Posts: 1665
Joined: Mon Dec 20, 1999 3:16 am

RE: MD80 Flap Sections, How Are They Extended/stow

Fri Apr 29, 2005 10:06 am

Quoting Bio15 (Reply 3):
I saw several more photos and understood the following: Flaps don't simply rotate on a wing hinge, but they displace themselves out as well.

That's because the flaps aren't hinged within the upper and lower camber, but approxmimately a foot and half ( .5 meters ) below it, in faired linkage/hinges, with some of the fairings also housing the actuators, the hinge point being at the very bottom of the fairings.

In this manner, for the initial flap settings ( as we progress from up to down ) they are de-facto fowler type flaps.

[Edited 2005-04-29 03:10:42]

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