A520
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Tech/Ops

Mon Aug 07, 2006 5:45 pm

Hi there,
Is there a fundamental design reason with engines are always below the wings and not on top of them on modern aircrafts? Putting the engines on top would solve ground clearance issues and allow to use higher dilution fans.
Thanks

[Edited 2006-08-07 10:46:35]
 
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HAWK21M
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RE: Tech/Ops

Mon Aug 07, 2006 6:10 pm

I may not win often, but I damn well never lose!!! ;)
 
A520
Topic Author
Posts: 103
Joined: Fri Jun 02, 2006 1:12 am

RE: Tech/Ops

Mon Aug 07, 2006 6:21 pm

Quoting HAWK21M (Reply 1):
Maybe the Title needs a Change

Yes, sorry, I mixed up between forum name and post name! Thanks for the link
 
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Starlionblue
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RE: Tech/Ops

Mon Aug 07, 2006 7:20 pm

Quoting A520 (Thread starter):
Is there a fundamental design reason with engines are always below the wings and not on top of them on modern aircrafts? Putting the engines on top would solve ground clearance issues and allow to use higher dilution fans.
Thanks

Putting the engines under and in front of the wings has several benefits (? where I am guessing):
- Counteract wing twisting.
- Easier to change engines.
- Less noise in the cabin.
- Marginally more protection from blade shedding for the cabin?
- Pylon can be more elasic and transfer less vibrations to the wing?
- Airflow is cleaner by putting the engine out in front and below.



Besides, engines on the wing are just plain ugly. Just look at the dreaded VFW-614:

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kaddyuk
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RE: Tech/Ops

Tue Aug 08, 2006 12:07 am

Quoting Starlionblue (Reply 3):
Airflow is cleaner by putting the engine out in front and below.

This being the main reason, the airflow over the top of the wing is FAR more critical than the air Underneath the wing, which is why engines and Pylon pods are slung forwards...
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LMP737
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RE: Tech/Ops

Tue Aug 08, 2006 5:09 am

Along with some of the reasons already stated servicing engines on traditional aircraft is easier. Also if you drop something you don't have to worry about damaging the wing.
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2H4
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RE: Tech/Ops

Tue Aug 08, 2006 5:57 am




Quoting Starlionblue (Reply 3):
Besides, engines on the wing are just plain ugly. Just look at the dreaded VFW-614:

Well, Honda made it work:


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 Wink




2H4


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Bobster2
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RE: Tech/Ops

Tue Aug 08, 2006 6:24 am

Which is better for a wheels-up landing or a water ditching? I think I'd rather see an engine hit the ground/water instead of a whole wing hitting (the Honda looks especially scary), but I don't know.
"I tell you this, no eternal reward will forgive us now for wasting the dawn." Jim Morrison
 
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Starlionblue
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RE: Tech/Ops

Tue Aug 08, 2006 11:45 am

Quoting Bobster2 (Reply 7):
Which is better for a wheels-up landing or a water ditching? I think I'd rather see an engine hit the ground/water instead of a whole wing hitting (the Honda looks especially scary), but I don't know.

If it's a crash, the engines will shear off anyway.

If it's slower than a crash, I'm sure the pilots on the board can enlighten you. My guess is that if you do it right you can belly land either with as much success.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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HAWK21M
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RE: Tech/Ops

Tue Aug 08, 2006 5:56 pm

Quoting 2H4 (Reply 6):
Well, Honda made it work:

I wonder why they did not use the common Fuselage Mounting.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
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Starlionblue
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RE: Tech/Ops

Tue Aug 08, 2006 8:56 pm

Quoting HAWK21M (Reply 9):
Quoting 2H4 (Reply 6):
Well, Honda made it work:

I wonder why they did not use the common Fuselage Mounting.

IIRC the party line is that this was more efficient aerodynamically.

It may well be different just for marketing differentiation reasons. Make the aircraft look memorable.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
N600RR
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RE: Tech/Ops

Thu Aug 17, 2006 1:00 pm

Quoting HAWK21M (Reply 9):
I wonder why they did not use the common Fuselage Mounting.

Perhaps there is less vibration/noise in the cabin as a result? Requires less structural loading reinforcements, as the engine weight can be supported by the MLG? Simplified fuel delivery? Simplified maintenance? All of the above?
"And the fluffy white lines that the airplane leaves behind are drifting right in front of the waning of the moon" -Cake
 
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HAWK21M
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RE: Tech/Ops

Thu Aug 17, 2006 3:00 pm

Quoting N600RR (Reply 11):
Perhaps there is less vibration/noise in the cabin as a result? Requires less structural loading reinforcements

Any Link to this Aircraft with more Tech Details.
regds
MEL
I may not win often, but I damn well never lose!!! ;)

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