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User currently onlineA520 From Switzerland, joined Jun 2006, 122 posts, RR: 0
Posted (7 years 11 months 4 weeks 1 day 12 hours ago) and read 2317 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
 
User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 1, posted (7 years 11 months 4 weeks 1 day 11 hours ago) and read 2306 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!
User currently onlineA520 From Switzerland, joined Jun 2006, 122 posts, RR: 0
Reply 2, posted (7 years 11 months 4 weeks 1 day 11 hours ago) and read 2297 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


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17002 posts, RR: 67
Reply 3, posted (7 years 11 months 4 weeks 1 day 10 hours ago) and read 2287 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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Click here for bigger photo!

Photo © Gerhard Plomitzer




"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineKaddyuk From Wallis and Futuna, joined Nov 2001, 4126 posts, RR: 26
Reply 4, posted (7 years 11 months 4 weeks 1 day 5 hours ago) and read 2221 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
User currently offlineLMP737 From , joined Dec 1969, posts, RR:
Reply 5, posted (7 years 11 months 4 weeks 1 day ago) and read 2163 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.

User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 6, posted (7 years 11 months 4 weeks 23 hours ago) and read 2151 times:
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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:


View Large View Medium
Click here for bigger photo!

Photo © Sergey Riabsev
View Large View Medium
Click here for bigger photo!

Photo © Mike Paschal




 Wink




2H4





Intentionally Left Blank
User currently offlineBobster2 From , joined Dec 1969, posts, RR:
Reply 7, posted (7 years 11 months 4 weeks 23 hours ago) and read 2141 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.

User currently offlineStarlionblue From Greenland, joined Feb 2004, 17002 posts, RR: 67
Reply 8, posted (7 years 11 months 4 weeks 18 hours ago) and read 2097 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."
User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 9, posted (7 years 11 months 4 weeks 11 hours ago) and read 2050 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!
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17002 posts, RR: 67
Reply 10, posted (7 years 11 months 4 weeks 8 hours ago) and read 2022 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."
User currently offlineN600RR From United States of America, joined Feb 2006, 171 posts, RR: 0
Reply 11, posted (7 years 11 months 2 weeks 5 days 16 hours ago) and read 1891 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
User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 12, posted (7 years 11 months 2 weeks 5 days 14 hours ago) and read 1872 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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