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MD80 Flap Sections, How Are They Extended/stowed?  
User currently offlineBio15 From Colombia, joined Mar 2001, 1089 posts, RR: 7
Posted (9 years 5 months 1 week 4 days 2 hours ago) and read 3681 times:

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

4 replies: All unread, jump to last
 
User currently offlineDALMD88 From United States of America, joined Jul 2000, 2559 posts, RR: 14
Reply 1, posted (9 years 5 months 1 week 3 days 23 hours ago) and read 3640 times:

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.

User currently offlineMiamiair From , joined Dec 1969, posts, RR:
Reply 2, posted (9 years 5 months 1 week 3 days 13 hours ago) and read 3587 times:

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).

User currently offlineBio15 From Colombia, joined Mar 2001, 1089 posts, RR: 7
Reply 3, posted (9 years 5 months 1 week 1 day 6 hours ago) and read 3453 times:

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


User currently offlineNKP S2 From United States of America, joined Dec 1999, 1714 posts, RR: 5
Reply 4, posted (9 years 5 months 1 week 1 day 5 hours ago) and read 3453 times:

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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