A twin engined 747...

[Shotgun Jon]

So, I know there is no such thing and as a commercial prospect the idea would never get off the ground, but that’s exactly my question.....would one physically fly?

I was reading on twitter people getting upset that the 747 is approaching the end of its life and that the new era of twins look boring and one person said why couldn’t they re-engine the 747.

In theory two GE-90’s from a 777 would produce circa 230,00lb of thrust, just shy of what the four engines on a 747-400 do and I assume there would be less drag and weight as well with only two engines....so, would it fly?!?

What do we think?

[Scrump]

Could call it the 747 Max.

[Starfighter]

GE90 or GE9x engines are too big to go under the wings and would need a full wing but redesign. Same problem as with 737max.

[Shotgun Jon]

Starfighter said:

GE90 or GE9x engines are too big to go under the wings and would need a full wing but redesign. Same problem as with 737max.

But the 737max did fly, albeit briefly.....so, I reckon the 747 would have sufficient thrust from two GE90’s to get off the ground.

[anonymous-user]

I imagine it would need a complete wing redesign, as it would have been designed for the weight and forces of 2 engines hanging from each of them.

I would think that there may be a shift in Centre of Gravity and other handling anomalies as well.

I would guess that you would be pretty much designing the wing from scratch again. Fitting 4 new (larger) engines to the Nimrod MRA4 didn’t work out well

[Europa1]

Coincidenally, my brother and I were watching one of the NatGeo (I think) channels at the weekend,and there was a documentary about the latest variant of the 747, in which they said one of the engines produces as much thrust as all 8 on a B52, so given when the 747 first flew, a 2 engined version to my inexpert brain seems plausible (although the aerodynamic problem above is a worry)

[V8LM]

Too close to the ground to be safe, and CoG too far forward to be practical.

[eldar]

Shotgun Jon said:

But the 737max did fly, albeit briefly.....so, I reckon the 747 would have sufficient thrust from two GE90’s to get off the ground.

Still seems to be selling well, flying or not...

[Zad]

Unless they put the engines above the wing..

You'd only need 45 foot tall engineers to service them!

[eldar]

Zad said:

Unless they put the engines above the wing..

You'd only need 45 foot tall engineers to service them!

Are there that many short engineers?

[JuniorD]

eldar said:

Zad said:

Unless they put the engines above the wing..

You'd only need 45 foot tall engineers to service them!

Are there that many short engineers?

You can hear them on their way to the base..."High Ho! High Ho! It's off to work we go..."

[FourWheelDrift]

V8LM said:

Too close to the ground to be safe, and CoG too far forward to be practical.

https://www.youtube.com/watch?v=NYYXoy7xbik

[Dr Jekyll]

anonymous said:

[redacted]

This.

One option for the 747SP was a three engine set up like the Tristar or DC10, but the complication wasn't the tail engine so much as redesigning the wing for one engine each side.

[mr_fibuli]

anonymous said:

[redacted]

If only they had some kind of computer system that could reliably trim out these side effects...

[anonymous-user]

mr_fibuli said:

anonymous said:

[redacted]

If only they had some kind of computer system that could reliably trim out these side effects...

By automatically shoving the nose forwards to stop it stalling? No need to tell the pilots about that.

It probably only needs one source of data too. Then pilots can fly both the 4 engine 747 and the new 2 engines one with minimal extra training.

[mcdjl]

They kind of had a go a bit more B52 style than you meant though: https://www.airliners.net/forum/viewtopic.php?t=41...

[Tony1963]

Don’t forget that the entire 747 airframe is very old tech now. Would you think a 1978 Cortina with a modern Ford engine and safety features would be practical to anyone except weirdos?

These aircraft are competing for sales against very, very tough opposition. A buyer looking at an ancient airframe wouldn’t be tempted, no matter what the engines are, if there’s a brand new Airbus available with a full fatigue life ahead of it.

[Zad]

JuniorD said:

You can hear them on their way to the base..."High Ho! High Ho! It's off to work we go..."

Don't be daft, they are car mechanics! How else do you think they get under cars to do oil changes?

[RalphyM]

Zad said:

Unless they put the engines above the wing..

You'd only need 45 foot tall engineers to service them!

Genuine question, why do the engines go under the wing? Is it just for practicalities of servicing/replacement or is there something more fundamental that means it’s a crap idea?

[Dr Jekyll]

RalphyM said:

Genuine question, why do the engines go under the wing? Is it just for practicalities of servicing/replacement or is there something more fundamental that means it’s a crap idea?

I think it's primarily maintenance. There have been exceptions.