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A Different Style Of Four Engined Jet?  
User currently offlineJessman From United States of America, joined Jul 2001, 1506 posts, RR: 8
Posted (10 years 5 months 2 weeks 10 hours ago) and read 3432 times:

Jets with two engines have them either wing mounted (777)

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Photo © Johan Kellerman

or tail mounted(MD-80).
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Photo © Paul Robbins



Jets with three engines have either two on the wing and one in the tail(MD-11)
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or all three on the tail (727)
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Why do jets with four engines only have them mounted on the wings(B747)
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Photo © Frank C. Duarte Jr.

.
Why no two wing mounted/two tail mounted jets?
Have there been any designs for a jet with two wing mounted/two tail mounted engines?
Just curious  Smile


15 replies: All unread, jump to last
 
User currently offlineDeltaffindfw From United States of America, joined Sep 2003, 1426 posts, RR: 1
Reply 1, posted (10 years 5 months 2 weeks 10 hours ago) and read 3403 times:

This could be close!


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[Edited 2003-11-09 04:53:31]

User currently offlineUSAFHummer From United States of America, joined May 2000, 10685 posts, RR: 53
Reply 2, posted (10 years 5 months 2 weeks 10 hours ago) and read 3401 times:

you forgot the VC-10/IL-62/Lockheed Jetstar class...four tail-mounted engines...

Greg



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User currently offlineAn-225 From United States of America, joined Sep 2000, 3950 posts, RR: 41
Reply 3, posted (10 years 5 months 2 weeks 10 hours ago) and read 3380 times:

You're forgetting something.


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Alex.



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User currently offlineFanofjets From United States of America, joined Apr 2000, 1943 posts, RR: 3
Reply 4, posted (10 years 5 months 2 weeks 9 hours ago) and read 3265 times:

I imagine that a design with two wing-mounted and two tail-mounted engines would pose center of gravity problems affecting handling or efficiency or both.

Here are some other engine configurations; none of these saw widespread use-
Two engines in pods and two on wing tips:

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Four engines buried in wing root:

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Two unusual two-engined configurations-

Two engines in tail:

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Photo © Sergey Riabsev



Two engines in wing roots:

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Photo © Frank Ebeling
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The aeroplane has unveiled for us the true face of the earth. -Antoine de Saint-Exupery
User currently offlineN243NW From United States of America, joined Jul 2003, 1609 posts, RR: 20
Reply 5, posted (10 years 5 months 2 weeks 9 hours ago) and read 3247 times:

Why no two wing mounted/two tail mounted jets?
Have there been any designs for a jet with two wing mounted/two tail mounted engines?

The question that our friend Jessman is asking is not "Why aren't there any jets with all four engines on the tail?".

I assume the aircraft would just be too complicated with the configuration (different styles of pylons, nacelles, etc.) and too hard to maintain (the mechanics would have to check both the wing-mounted and tail-mounted engines, however it seemed to work for the DC10 & L1011). I don't, however, see any significant advantages for this configuration compared to others, but I have turned the idea over in my head more than once before. There is also the chance that by the time that any aircraft manufacturers might have thought of this (if they ever did), the commercial jets became more simple and efficient with only two engines. Any other ideas or details would be appreciated, as I'd also like to know of your thoughts or facts!
-N243NW Big grin



B-52s don't take off. They scare the ground away.
User currently offlineJessman From United States of America, joined Jul 2001, 1506 posts, RR: 8
Reply 6, posted (10 years 5 months 2 weeks 9 hours ago) and read 3196 times:

I must admit, I did completely forget about the four tail mounted engines. I have never seen one of those aircraft in real life.
But that does make me wonder, are the two inside engines hard to get to? It seems like they would be a problem to maintain.  Smile


User currently offlineJetguy From , joined Dec 1969, posts, RR:
Reply 7, posted (10 years 5 months 2 weeks 8 hours ago) and read 3104 times:

There have also been 4-engine aircraft with the engines mounted on top of the wings - there was an experimental USAF transport in that configuration. I don't remember who built it, but I believe that it's on display at the Pima Air Museum in Tucson. The Gemans also built a small jet with two pod mounted engines slung above the wings - a Fokker I believe. I think that designers have hung engines just about anywhere you could possible hang an engine over the years. Wasn't there an early USAF bomber that had its engines pod mounted on the forward fuselage?

jet's


User currently offlineL-188 From United States of America, joined Jul 1999, 29699 posts, RR: 59
Reply 8, posted (10 years 5 months 2 weeks 8 hours ago) and read 3096 times:

You also forgot mounting two engines over the wing.


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How about a single engine over the cabin?


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User currently offlineCoronado990 From United States of America, joined Oct 2003, 1593 posts, RR: 2
Reply 9, posted (10 years 5 months 2 weeks 8 hours ago) and read 3060 times:

Regarding the two engines on the wing, two engines on the tail design: I would think the engines mounted on the sides of the tail would tend to suck in the exhaust from the wing mounted engines. Probably not a good thing. The DC-10 engine sat up high enough to avoid this problem.


Uncle SAN at your service!
User currently offlinePW100 From Netherlands, joined Jan 2002, 2326 posts, RR: 12
Reply 10, posted (10 years 5 months 2 weeks 3 hours ago) and read 2957 times:

Don't forget these:


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PW100



Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
User currently offlineNudelhirsch From Germany, joined Oct 2003, 1438 posts, RR: 19
Reply 11, posted (10 years 5 months 2 weeks 3 hours ago) and read 2943 times:

I'm not an expert in aircraft design. I could imagine, that the engine position is actually influencing flight stability and flight behavior of the plane.
Seeing the two-eng wing-mounted as a "normal" way, 4 on the wing still pretty normal, DC-10-style to increase vertical maneuverability (is this a word???) by a third centered thrust. I read in a book, that this layout helped a crew to land a DC-10 wihtout rudders, to control bank by the wing engines, and descend and levelling out by the tail engine.
I also read, that there is an effect, which uses the exhaust stream of the engine to flow over the wing, creating more uplift.
It probably also depends on engines on the market and their power. If, like Coronado mentioned, exhaust in inflow wouldn't be a problem - what sense would it make to mount 4 engines to a 737 - two on wing, two on tail - would probably be great looking, but probably no sense in economical ways.
See also the thread about why the BAE146 has 4 instead of 2 engines...

The DC-10 had pretty big engines, and placed in a triangle, which would, like mentioned enable the crew to use the the engines for steering. I don't think, a "4-engine, 2-wing 2-tail concept" would provide these effects as well.

Just my stuff, I really am not an expert, this is what I gathered by reading and thinking. Interesting thread though!



Putana da Seatbeltz!
User currently offlineRthrbeflying86 From United States of America, joined Oct 2003, 243 posts, RR: 1
Reply 12, posted (10 years 5 months 1 week 6 days 23 hours ago) and read 2762 times:

I read in a book, that this layout helped a crew to land a DC-10 wihtout rudders, to control bank by the wing engines, and descend and levelling out by the tail engine.

Probably a book about United 232.



I'd rather be flying.
User currently offlineJessman From United States of America, joined Jul 2001, 1506 posts, RR: 8
Reply 13, posted (10 years 5 months 1 week 6 days 17 hours ago) and read 2653 times:

For the design I was thinking a jet along the size of a A340. It seems to have engines that would be small enough to be mounted onto the tail.
With all the different places designers have put engine, I would have thought this would have been tried.
I suppose the exhaust thing could be a reason.
Some pretty cool pics have been put up on this thread. That's great.  Smile


User currently offlineJgardiner From Canada, joined Mar 2001, 114 posts, RR: 0
Reply 14, posted (10 years 5 months 1 week 5 days 21 hours ago) and read 2490 times:

One advantage of mounting the engines on the wing is that the weight is used to counteract the aerodynamic forces that want to twist the wing. This way the wing structure can be made lighter.

Another advantage is that mounting the engines on the tail limits the amount that you can stretch the fuselage.




User currently offlineMandala499 From Indonesia, joined Aug 2001, 6590 posts, RR: 75
Reply 15, posted (10 years 5 months 1 week 5 days 16 hours ago) and read 2389 times:

Engines on the wings = Balanced weights centered around the wing/cg/cl.
Engines on the tail = Nose heavy... resulting in long nose and short tail...

Combination... have you compared the DC10/MD11's wing position relative to the overall body with a 777 ? Now slap another engine on the tail and see that wing move further back... In the end, you might aswell have 4 engines on the tail, or on the wing. Not to mention the maintenance complications. 2 engines with all the connections on the top, and 2 engines with connections to the side... Hmmm, sounds like a nightmare to me...

And we haven't even gone into the potential use of cabin space if the engines are on the wings!...

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
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