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WN732
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Question Regarding 737 Classic Wing

Fri Jul 31, 2020 1:21 am

The 737 Classic shares the wing design with the 737 Jurassic. I know that the JT8D extended aft of the wing while the CFM models don't. But why did Boeing not make a design change with the pylon that extends out from behind the engine on the Classic? Did it perform some sort of ballast to counter the weight of the larger engine? What was its purpose?

I did notice that it had slots for the flaps just as the original 737 did, but any further info would be great.

Obviously the NG and beyond don't, but they have a much different wing.
 
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Starlionblue
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Re: Question Regarding 737 Classic Wing

Fri Jul 31, 2020 2:13 am

Do you mean, why does the pylon on the Classic seem to extend behind the wing?

I don't think that is a pylon extension. It seems to be a flap track fairing. Area ruling probably had something to do with it as well.

Image
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
WN732
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Joined: Sat Feb 26, 2011 12:49 am

Re: Question Regarding 737 Classic Wing

Fri Jul 31, 2020 5:06 am

Starlionblue wrote:
Do you mean, why does the pylon on the Classic seem to extend behind the wing?

I don't think that is a pylon extension. It seems to be a flap track fairing. Area ruling probably had something to do with it as well.

Image


That's what I guessed, but it doesn't serve any other function? Thank you for your response.
 
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Starlionblue
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Re: Question Regarding 737 Classic Wing

Fri Jul 31, 2020 5:15 am

At a guess, it also controls airflow from the engine to the back of the wing. The engine is rather near the wing compared to more modern underslung designs.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
VSMUT
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Joined: Mon Aug 08, 2016 11:40 am

Re: Question Regarding 737 Classic Wing

Fri Jul 31, 2020 9:02 pm

Starlionblue wrote:
Do you mean, why does the pylon on the Classic seem to extend behind the wing?

I don't think that is a pylon extension. It seems to be a flap track fairing. Area ruling probably had something to do with it as well.

Image


It is the engine pylon. It's fixed, doesn't extend with the flaps. A very characteristic trait if you need to identify if it's an NG or a Classic.
 
LH707330
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Re: Question Regarding 737 Classic Wing

Fri Jul 31, 2020 10:55 pm

The Classic had a couple of changes from the Jurassic: more chord and a slightly longer span, see here for details: http://www.b737.org.uk/737classic.htm

That aft pylon does have flap mechanisms in it, probably a similar design to the Jurassics, which is why they kept it there. The NG went to a new wing, so they used that chance to clean it up a bit.

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