Boston92
Topic Author
Posts: 2553
Joined: Wed Aug 09, 2006 6:56 am

Quad-Engine Configuration

Mon Dec 11, 2006 7:36 am

Is there an a/c out there that has four engines; 2 rear and 2 under-wing. So kind of like a MD80 with two additional engines under the wing. With this configuration, you could have a large wide-body and have a more distributed weight than with a 747.

How long until an a/c manufacturer make an a/c with this configuration?

Any comments are welcome.
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ebj1248650
Posts: 1517
Joined: Mon Jun 06, 2005 6:17 am

RE: Quad-Engine Configuration

Mon Dec 11, 2006 7:48 am

Quoting Boston92 (Thread starter):
Is there an a/c out there that has four engines; 2 rear and 2 under-wing. So kind of like a MD80 with two additional engines under the wing. With this configuration, you could have a large wide-body and have a more distributed weight than with a 747.

How long until an a/c manufacturer make an a/c with this configuration?

Any comments are welcome.

There's nothing out there ... yet ... like you described. The VC-10 and Super VC-10 have four engines in the rear, as does the IL-62. The L1011, DC-10, and MD-11 have one engine in the rear and one engine under each wing. I don't really think you're going to see an airliner designed with the configuration you're talking about. As large as engines are getting, it's likely all four engine layouts will mount 2 engines under each wing.
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OldAeroGuy
Posts: 3188
Joined: Sun Dec 05, 2004 6:50 am

RE: Quad-Engine Configuration

Mon Dec 11, 2006 9:25 am

Quoting Boston92 (Thread starter):
With this configuration, you could have a large wide-body and have a more distributed weight than with a 747.

But you don't want to distribute the weight in this manner.

Keeping the all the engines on the wings will:

Make it easier to balance the airplane by keeping the zero fuel weight CG near the wing Aerodynamic Center (AC).

Provide bending moment relief for the wing, resulting in a lighter wing structure.

You do need to carefully design the outboard engine nacelle/strut and outboard wing to avoid excessive cruise drag though.
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ChrisI1024
Posts: 50
Joined: Mon Jul 31, 2006 10:21 am

RE: Quad-Engine Configuration

Mon Dec 11, 2006 10:26 am

Not a civil (or even a production) aircraft, but the Junkers Ju 287 had two forward-mounted engines on the fuselage and one under each forward-swept wing. It was a funny looking thing.