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bobcat
Topic Author
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Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 7:31 am

Why are engines mouted under, not above, the wing?

I realize this is a silly question... but
I saw a program on TDC last week.
They were talking about designing the
747s in the 60's. One sketch drawing
showed 4 engines mouted above the
wings...
 
rw774477
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 7:33 am

noise, maintenance

rw774477
 
SegmentKing
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 7:36 am

so the fuel will stay warm

*smirk*

-nate
~ ~ ~ ~ pRoFeSsIoNaL hUrRiCaNe DoDgEr ~ ~ ~ ~
 
EGGD
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 7:36 am

Not only that, wouldn't it effect aerodynamics and the airflow over the wings?
 
svenvdm
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 7:37 am

Very interesting question...

Don't quote me on this but I've heard that the weight of the engine is compensated best below the wing because of the lift created there.
 
HAL
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 7:40 am

Mostly for structural reasons. Hanging the engines under the wing allows gravity to keep the engines centered under their pylons. The engines themselves are probably the densest concentrations of metal in the planes, and therefore the heaviest parts of the plane. If they were mounted above the wing, they'd have to have much stronger (and heavier) pylons. Also, the farther forward (ahead) of the wing they're mounted, the better for airflow. Mounting above and ahead of the wings would be an engineering nightmare.

HAL
One smooth landing is skill. Two in a row is luck. Three in a row and someone is lying.
 
kjet12
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 7:43 am

There was a european (french?) aircraft called the VFW 614 with engines above the wings.


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A330DAT
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 8:02 am

It's German


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OPNLguy
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 8:12 am

To add to what HAL said, keeping that much dense weight on the underside of the wing would tend to make the overall aircraft design more failsafe, i.e. an above-wing engine separating from the wing and damaging/destroying said wing in the process...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
Starship
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 8:23 am

Another aspect to consider is an uncontained engine failure. Flying pieces of engine debris could easily penetrate the cabin causing rapid decompression at altitude, and causing serious injury and death to passengers. Likewise engine parts could easily penetrate the wing and fuel tanks with the potential of causing a major wing fire. This has happened on a number of occasions even with the engines mounted below and ahead of the wing.

The real reason why the engines are mounted below and ahead of the wing have to do with an enormous amount of research conducted by Boeing during the development of the XB-47 and many hours experimenting in the wind tunnel. This is all described in great detail in Chapter 4 of the book Wide Body - The Making Of The Boeing 747 by Clive Irving. Over 50 different positions of mounting engines were tried before settling on pylon mounted engines in their now traditional location.
Behind every "no" is a "yes"
 
Notar520AC
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 9:02 am

The Boeing YC-14 ( I think that's the one ) has the engines IN the wings.
BMW - The Ultimate Driving Machine
 
Skyway1
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 9:20 am

In addition to this discussion, I think the Antonov 72-74 aircrafts have their engines mounted above the wings as well.

Chris
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slawko
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Fri Feb 01, 2002 10:30 am

Angines mounted over the wing as in the AN72 increase the STOL capabilities of the airplane, and I have read that they improve the performance of the AC in other ways, but it is harder to maintain the engines, and to pump fuel into the engine.
"Clive Beddoe says he favours competition, but his actions do not support that idea." Robert Milton - CEO Air Canada
 
vfw614
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RE: Why Are Engines Mouted Under, Not Above, The Wing?

Sat Feb 02, 2002 5:37 am

The  Big thumbs up VFW614  Big thumbs up was built with rough field capability in mind and it was considered useful to have the engines mounted above the wings for that purpose.

Quite honestly, I cannot see the maintenance advantages compared to aircraft with aft-mounted engines like the 727 or the DC9 - for sure the engines on the VFW614 were more easily accessible (from both sides) than the engines on those airplanes.

Long live the VFW614  Wink/being sarcastic Germany built regio-jets when the ERJ145 and the CanRJ were still 20 years away... Too bad it was a commerical failure  Crying

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