simjim
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747-8I With Three GEnx Engines And One CFM56?

Sat Nov 24, 2012 5:54 am

I recently saw a photo of the GE 747-100 Test Bed Aircraft flying with one GEnx engine and wondered what the CASM would be for the 747-8I, if you placed three GEnx engines and one CFM56-7B27 (738 engine) on it?

On a 4,000 nm mission, fully loaded with passengers and cargo, do you think it would be less efficient, more efficient or about the same as a 77W flying the same mission?
 
B777LRF
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RE: 747-8I With Three GEnx Engines And One CFM56?

Sat Nov 24, 2012 12:08 pm

I think it would never be allowed to leave the ground, but if it did it would be with a take-off weight so restricted it wouldn't even by funny. Imagine if you loose one engine right after lift off, and that engines happens to be a GEnx on the same side as the puny little CFM. You'd be in a world of pain unless you're a bonafide test pilot, which very few airline pilots are.

An operation such as the one you suggested falls under "test flight" not "commercial revenue generating" ditto.
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Stitch
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RE: 747-8I With Three GEnx Engines And One CFM56?

Sat Nov 24, 2012 3:31 pm

Quoting simjim (Thread starter):
I recently saw a photo of the GE 747-100 Test Bed Aircraft flying with one GEnx engine and wondered what the CASM would be for the 747-8I, if you placed three GEnx engines and one CFM56-7B27 (738 engine) on it?

It would be higher because you'd be payload-restricted so you couldn't fill all the seats.

Quite simply, the 747-8 has four GEnx1B-67 engines because it needs four GEnx1B-67 engines.  
 
PapaChuck
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RE: 747-8I With Three GEnx Engines And One CFM56?

Sun Nov 25, 2012 3:42 pm

The easiest and most cost-effective solution would be to de-rate all four GEnx engines and file the paperwork to operate at a reduced MTOW. Airlines do this all the time when they don't intend to exploit an aircraft's full capabilities.

Edit: Better yet, just get your hands on an aircraft tailored to the type of routes you intend to fly. A 777-300 (non-ER) can carry a full payload close to 4000 miles. Why go through the headache of modifying a 747-8 to do something it was never intended to do when you can just buy the right airplane for the job in the first place?

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[Edited 2012-11-25 08:08:19]
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