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A520 From Switzerland, joined Jun 2006, 112 posts, RR: 0
Posted (6 years 9 months 2 weeks 5 days 15 hours ago) and read 1821 times:

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]

12 replies: All unread, jump to last

HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58
Reply 1, posted (6 years 9 months 2 weeks 5 days 15 hours ago) and read 1810 times:

http://www.airliners.net/discussions...h_ops/read.main/120117/6/#ID120117
Maybe the Title needs a Change. Smile

regds
MEL

Think of the brighter side!

A520 From Switzerland, joined Jun 2006, 112 posts, RR: 0
Reply 2, posted (6 years 9 months 2 weeks 5 days 15 hours ago) and read 1801 times:

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

Starlionblue From Hong Kong, joined Feb 2004, 15870 posts, RR: 66
Reply 3, posted (6 years 9 months 2 weeks 5 days 14 hours ago) and read 1791 times:

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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Photo © Gerhard Plomitzer

"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo

Kaddyuk From Wallis and Futuna, joined Nov 2001, 4125 posts, RR: 28
Reply 4, posted (6 years 9 months 2 weeks 5 days 9 hours ago) and read 1725 times:

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...

Whoever said "laughter is the best medicine" never had Gonorrhea

LMP737 From , joined Dec 1969, posts, RR:
Reply 5, posted (6 years 9 months 2 weeks 5 days 4 hours ago) and read 1667 times:

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.

2H4 From United States of America, joined Oct 2004, 8950 posts, RR: 62
Reply 6, posted (6 years 9 months 2 weeks 5 days 3 hours ago) and read 1655 times:

AIRLINERS.NET CREW
HEAD DATABASE EDITOR

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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Click here for bigger photo!

Photo © Sergey Riabsev

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Photo © Mike Paschal

2H4

Intentionally Left Blank

Bobster2 From , joined Dec 1969, posts, RR:
Reply 7, posted (6 years 9 months 2 weeks 5 days 3 hours ago) and read 1645 times:

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.

Starlionblue From Hong Kong, joined Feb 2004, 15870 posts, RR: 66
Reply 8, posted (6 years 9 months 2 weeks 4 days 21 hours ago) and read 1601 times:

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." - from Citadel by John Ringo

HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58
Reply 9, posted (6 years 9 months 2 weeks 4 days 15 hours ago) and read 1554 times:

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

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

Think of the brighter side!

Starlionblue From Hong Kong, joined Feb 2004, 15870 posts, RR: 66
Reply 10, posted (6 years 9 months 2 weeks 4 days 12 hours ago) and read 1526 times:

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." - from Citadel by John Ringo

N600RR From United States of America, joined Feb 2006, 171 posts, RR: 0
Reply 11, posted (6 years 9 months 1 week 2 days 20 hours ago) and read 1395 times:

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

HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58
Reply 12, posted (6 years 9 months 1 week 2 days 18 hours ago) and read 1376 times:

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

Think of the brighter side!

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