Simviation Forum - A380 question

Reply #15 - Nov 6^th, 2006 at 8:52am

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The only thing that can do that flight is the Boeing 777-200LR Wink

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Reply #16 - Nov 8^th, 2006 at 8:13pm

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Does this -- http://seattlepi.nwsource.com/business/247908_qantas11.html -- means that the triple 7 can? What about the a340-500 or -642

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Reply #17 - Nov 12^th, 2006 at 12:50pm

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Another question: why is there no GE engine option? Surely it'd be only fitting that the worlds largest airliner be fitted with the GE-90 engines, the worlds largest jet engine?

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Reply #18 - Nov 12^th, 2006 at 5:48pm

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Another question: why is there no GE engine option? Surely it'd be only fitting that the worlds largest airliner be fitted with the GE-90 engines, the worlds largest jet engine?

GE90 design is not suitable for quads.
It s too heavy and packs too much power.

Simply put, the A380 dont need the excessive thrust and certainly can live without the additional weight.

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Reply #19 - Nov 12^th, 2006 at 6:37pm

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Wouldn't the additional power offset the additional weight?

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Reply #20 - Nov 12^th, 2006 at 8:12pm

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Wouldn't the additional power offset the additional weight?

It doesn't need it. And what would be the point? Tongue

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Reply #21 - Nov 13^th, 2006 at 9:42am

Nexus Offline
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Wouldn't the additional power offset the additional weight?

Additional power means additional fuel consumption to cope with the added weight... And you can't increase the volume of the fueltanks.
Congrats, you have just reduced the range of the A380.
I'm sure the airlines enjoy that.

Also, read Woodlouse's reply. Pretty much sums it up.

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Reply #22 - Nov 13^th, 2006 at 10:44am

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Stupid me. I thought it would increase the range. *bangs head on wall*

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Reply #23 - Nov 13^th, 2006 at 11:20am

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Stupid me. I thought it would increase the range. *bangs head on wall*

More powerful engines doesnt necessary equal increased range. I bet that four GE90's will consume considerably more amount of fuel than the current engines available for the A380.

Also throw in the jet engines need for high RPMs to be effective, you soon realize that this can not be done. If you'd keep four GE90's at 90% in cruise, you'd exceed MMO

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Reply #24 - Nov 14^th, 2006 at 6:00am

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Actually, GE-90 or its Rolls-Royce equivalent should be pretty comfortable to power a A380-sized trijet.

So would you like to fly a doubledecker trijet? And would you prefer to mount a GE90 in the tailcone with S-duct, like Tristar, ot above tail like DC-10 and MD-11?

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Reply #25 - Nov 14^th, 2006 at 7:00am

Nexus Offline
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An A380 tri-jet, now that is interesting

For design purposes I'd put an S-duct.

The A380-800 is a rather chubby aircraft and would not like to lose some of the rudder surface that has to be sacrificed in order to give way to a straight duct (á la DC10)
And should we make the tailplane higher, then it wont fit in hangars Grin

With an S-duct, you pretty much leave the rudder intact, at the cost of some engine efficiency. But that's rather minimal I believe ???

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Reply #26 - Nov 14^th, 2006 at 9:38am

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Quote:

Actually, GE-90 or its Rolls-Royce equivalent should be pretty comfortable to power a A380-sized trijet.

So would you like to fly a doubledecker trijet? And would you prefer to mount a GE90 in the tailcone with S-duct, like Tristar, ot above tail like DC-10 and MD-11?

Heck yeah! Grin

I'd choose the S-duct style.

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Reply #27 - Nov 15^th, 2006 at 6:26am

chornedsnorkack Offline
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Quote:

More powerful engines doesnt necessary equal increased range. I bet that four GE90's will consume considerably more amount of fuel than the current engines available for the A380.

Also throw in the jet engines need for high RPMs to be effective, you soon realize that this can not be done. If you'd keep four GE90's at 90% in cruise, you'd exceed MMO

Er, why MMO?

If you add power to a plane then I do not think it increases range... see Virgin Atlantic GlobalFlyer, which is deliberately underpowered.

What adding power does do:

Your takeoff roll gets shorter (assuming the rotation speed is unchanged). But the braking distance in a rejected takeoff is not getting any shorter.

Initial climb gradient gets steeper - more excess power, easier to clear terrain ahead, less time to reach a given flight level.

Cruise altitudes increase - after all, a plane climbs until the engines derate to equal drag...

Landing roll is not getting any shorter. However, the gradients of go-around get better.

So... there was recently a 747 that landed in Rand Airport. 1500 m runway, and it is hot and high! Can A380 do the same?

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Reply #28 - Nov 15^th, 2006 at 10:04am

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I was talking about the cruise phase.
Any jet engine likes to run at high rpms, or else the relationship between fuel burn and thrust produced will be worse.

SO...if you run all four GR90s on high RPMs the aircraft will likely exceed the barberpole, since the aircraft is greatly overpowered .

The cruise altitude will increase, but due to regulations the A380 might not be able to fly higher unless the environmental system is re-designed (On most jets it is not the structural strenght that limits the operating ceiling, but the pressurization system)

And I never did say the A380 would gain range, I was saying it will LOSE range with four GE90's

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Reply #29 - Nov 15^th, 2006 at 10:45am

chornedsnorkack Offline
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Quote:

I was talking about the cruise phase.
Any jet engine likes to run at high rpms, or else the relationship between fuel burn and thrust produced will be worse.

SO...if you run all four GR90s on high RPMs the aircraft will likely exceed the barberpole, since the aircraft is greatly overpowered .

The cruise altitude will increase, but due to regulations the A380 might not be able to fly higher unless the environmental system is re-designed (On most jets it is not the structural strenght that limits the operating ceiling, but the pressurization system)

And I never did say the A380 would gain range, I was saying it will LOSE range with four GE90's

Indeed. That´s where I am inclined to agree. A380 is probably not underpowered to the extent where adding power would increase range. Mind you, there is still the phase of climb to cruise, though.

Does loss of power decrease range? One of the Route Proving Flights is supposed to be Johannesburg - Sydney - over the South Pole. Would you like being on an A380 over the interior of Antarctic continent and lose power in one engine - would the fuel last to Sydney?

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