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Could The A390 Be A Twin Engine A380 Replacement?  
User currently offline747400sp From United States of America, joined Aug 2003, 3616 posts, RR: 2
Posted (2 years 8 months 2 weeks 2 days 7 hours ago) and read 9280 times:

I know I ask about twin engines double deck airliners before, but as we see the A340 spot being replaced by the A350 XWB, I wonder, in 20 or 30 years from now, could we see an double deck twin engine A390, taking the A380 spot at Airbus?

22 replies: All unread, jump to last
 
User currently offlinehorstroad From Germany, joined Apr 2010, 268 posts, RR: 0
Reply 1, posted (2 years 8 months 2 weeks 2 days 7 hours ago) and read 9287 times:

I think in 20 or 30 years we will start going away from this tube-with-wings - design. so I imagine there will be a flying wing replacing the A380 instead of a twin engined double deck tube.
an engine that replaces two Trent 900 needs more than 700kN thrust. this is 40% more than the GE90. I don´t think a turbofan engine can produce that much thrust. maybe a ducted fan but even this would be huge.

but on the other hand, who would have imagined a 512kN turbo fan engine 30 years ago? or a 600t aircraft?

we will see...


User currently offlinenomadd22 From United States of America, joined Feb 2008, 1864 posts, RR: 0
Reply 2, posted (2 years 8 months 2 weeks 2 days 6 hours ago) and read 9249 times:

I doubt if the market would be anywhere nearly big enough to justify development of an engine that size.


Andy Goetsch
User currently offlineStitch From United States of America, joined Jul 2005, 30986 posts, RR: 86
Reply 3, posted (2 years 8 months 2 weeks 2 days 5 hours ago) and read 9186 times:
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Well there is keesje's Ecoliner concept...

User currently offlinePapaChuck From United States of America, joined Aug 2010, 136 posts, RR: 0
Reply 4, posted (2 years 8 months 2 weeks 2 days 4 hours ago) and read 9152 times:

The truth is, only time will tell if there will an A380-sized twin in the future. Personally, I think it is a distinct possibility. Here are my thoughts:

First, consider the 747. This aircraft was possible because high-bypass turbofans like the JT9D in the 50,000 lb. thrust range were developed. At the time, that was pretty much the most thrust you could wrangle out of a single powerplant.

Jump ahead 30 years to the 777. With the GE-90, the 777-300ER has become an airplane that can, with only two engines, do pretty much everything the early 747's could do with four. Not surprisingly, the 777 has sold very well over the last 15 years. My point here being, engine advancements allowed a twin engine aircraft to assume roles that were previously limited to quads. In 1970, a turbofan making 120,000 lbs. of thrust was just a pipe dream. Today, it's no big deal.

If we jump ahead another 30 years, the first question we need to ask is if a powerplant in the 160-180,000 lb. thrust range could be developed. Considering how much ground has been covered between the JT9D and GE-90, I think it could be done. If so, then an A380-sized twin could technically be possible.

The next question we need to ask regards the market need for such an aircraft. Ironically, I think current A380 sales will be the barometer. The four-engined 747 sold well, which indicted that there was a market for the twin-engined 777-300ER. If the A380 ultimately become a strong seller, I think that would be a reasonable indication that the market could support a comparably sized twin. If Airbus sells a thousand A380's, I'd place my bets on a superjumbo twin being developed.

PC



In-trail spacing is a team effort.
User currently offlinecosmofly From United States of America, joined May 2009, 649 posts, RR: 0
Reply 5, posted (2 years 8 months 2 weeks 2 days 3 hours ago) and read 9114 times:

How about just double barrel the 787-9   Boeing can snap them together quickly like the F-82 Twin Mustang.

MTOW of 2x789 is still less than that of the A380.

[Edited 2012-01-05 11:35:31]

User currently offlineprebennorholm From Denmark, joined Mar 2000, 6449 posts, RR: 54
Reply 6, posted (2 years 8 months 2 weeks 1 day 18 hours ago) and read 8904 times:

Quoting PapaChuck (Reply 4):
If we jump ahead another 30 years, the first question we need to ask is if a powerplant in the 160-180,000 lb. thrust range could be developed.

An A380 has 210 to 216 klb takeoff thrust with one engine shut down after V1. A twin A380 would need the same on each engine.

So the jump is almost 100% on top of the current GE90-115B.

Technically it could probably be done. But the market is way too small to cover development costs. Sharing the R&D costs over the limited market would make the unit cost astronomical.



Always keep your number of landings equal to your number of take-offs, Preben Norholm
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17039 posts, RR: 66
Reply 7, posted (2 years 8 months 2 weeks 1 day 16 hours ago) and read 8856 times:

Quoting horstroad (Reply 1):
an engine that replaces two Trent 900 needs more than 700kN thrust. this is 40% more than the GE90.

Much more than that. You forgot engine out requirements.

The Trent 972 that Qantas uses has 72k lb (320kN) of thrust. With an engine out that's 216k lb (960kN) total from three engines. On a hypothetical 380 twin, you would need to get that thrust from ONE engine to handle an engine out. That's 87% more thrust than a GE-90.

Quoting PapaChuck (Reply 4):
In 1970, a turbofan making 120,000 lbs. of thrust was just a pipe dream. Today, it's no big deal.

Still a big deal, but I take your point.  



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineblueflyer From United States of America, joined Jan 2006, 4000 posts, RR: 2
Reply 8, posted (2 years 8 months 2 weeks 1 day 16 hours ago) and read 8846 times:
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Quoting PapaChuck (Reply 4):
The four-engined 747 sold well

One of the reasons it sold well, especially the earlier versions, was because it was the longest range aircraft available at the time. Many airlines bought a 747 not for the capacity, but for the range. Thus the 777 sold well because it had the range of a 747 (and some) for a lower capacity/cost, making it better suited for many airlines' operations.

Since range is no longer than driving factor for the A380, I don't believe that you can draw the same parallel between the A380 and a hypothetical A390 that you did between the 747 and 777.



I've got $h*t to do
User currently offlinePapaChuck From United States of America, joined Aug 2010, 136 posts, RR: 0
Reply 9, posted (2 years 8 months 2 weeks 1 day 9 hours ago) and read 8714 times:

I made a few assumptions with my thoughts above and I think I need to clarify a bit.

With another 30 years of material and structural advancements, I would hope a twin with the same capacity and range of the current A380 would be able to lose a little weight. Get the MTOW down to around a million pounds, then 180k engines would be sufficient. At the current A380 weights of over 1.2 million pounds, you would indeed need at least 200k per side.

Or perhaps a RATO supplement like the early 727s, or an additional engine like the Trident, but I digress...

Also, I understand that the 747/777 comparison isn't the best. It was a generalization on my part. All I'm trying to say is that when engine technology catches up, we could possibly see a superjumbo twin replacing the A380 in certain roles. The 777 didn't replace the 747 outright but instead complimented the 747 in the long range, high capacity role. True, the 777 may have hurt 747 sales, but it didn't completely do away with the need for a 747 on certain routes.

PC



In-trail spacing is a team effort.
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 79
Reply 10, posted (2 years 8 months 2 weeks 1 day 8 hours ago) and read 8696 times:

Quoting PapaChuck (Reply 9):
All I'm trying to say is that when engine technology catches up, we could possibly see a superjumbo twin replacing the A380 in certain roles.

It's not an engine technology problem. We know how to built a 200k engine if we want one...but there's just no market for an engine that size to justify the huge cost to develop it.

The enabler for the whole idea won't be engine technology, it will be growth in air travel to the point that A380 sized aircraft become common enough that an engine company will be willing to go for that market.

Tom.


User currently offlinepanais From Cyprus, joined May 2008, 463 posts, RR: 0
Reply 11, posted (2 years 8 months 2 weeks 1 day 7 hours ago) and read 8671 times:

Quoting 747400sp (Thread starter):
, could we see an double deck twin engine A390

We will probably see one, however you are making 2012 assumptions for 2032-2042.

I would go with the assumption that 6 engines might be more economical if they are incorporated into the wing and can be replaced within 20 minutes?


User currently offlinePapaChuck From United States of America, joined Aug 2010, 136 posts, RR: 0
Reply 12, posted (2 years 8 months 2 weeks 1 day 7 hours ago) and read 8661 times:

Which is exactly why I said that A380 sales will be a strong indication whether or not the superjumbo twin would be worth the investment. I too share your skepticism that the market for A380-sized aircraft will be large enough to justify both an airframer and engine maker to pony up the cash and give it a go. If there was a reasonable expectation to sell 1500 frames over twenty years, then it might be worth the investment. Personally, I doubt you could sell more than 150. Currently, there just isn't enough demand for the A380 to warrant a twin engined development. In 30 years, who knows? Time will tell.

PC



In-trail spacing is a team effort.
User currently offlineMarkC From United States of America, joined Apr 2006, 259 posts, RR: 0
Reply 13, posted (2 years 8 months 2 weeks 23 hours ago) and read 8529 times:

Quoting tdscanuck (Reply 10):
It's not an engine technology problem. We know how to built a 200k engine if we want one...but there's just no market for an engine that size to justify the huge cost to develop it.

The enabler for the whole idea won't be engine technology, it will be growth in air travel to the point that A380 sized aircraft become common enough that an engine company will be willing to go for that market.

Yeah, spot on.

Technology gets you higher bypass ratios, turbine inlet temps, lower noise, lower fuel comsupmtion, and better durability.
Look at the PW610. I've seen the parts in that engine. Lot of technology there....and what?...1,000 lbf.
We could have made a 200k engine 20 years ago, but it would have essentially be a scaled up PW4000 with all those parameters comperable to an early 90's design.


User currently offlinerwessel From United States of America, joined Jan 2007, 2351 posts, RR: 2
Reply 14, posted (2 years 8 months 2 weeks 16 hours ago) and read 8429 times:
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Quoting cosmofly (Reply 5):
How about just double barrel the 787-9 Boeing can snap them together quickly like the F-82 Twin Mustang.

That would certainly solve the placement problem for the middle engine for a tri-jet!   


User currently offlinemy235 From United States of America, joined Mar 2009, 92 posts, RR: 0
Reply 15, posted (2 years 8 months 2 weeks 12 hours ago) and read 8375 times:

The World is only so big. I believe airplanes don't need to keep getting bigger. Although look at the variation in birds as far as size goes.

User currently offlineStarlionblue From Greenland, joined Feb 2004, 17039 posts, RR: 66
Reply 16, posted (2 years 8 months 2 weeks 12 hours ago) and read 8372 times:

Quoting my235 (Reply 15):
The World is only so big. I believe airplanes don't need to keep getting bigger. Although look at the variation in birds as far as size goes.

"need" has never been a driving force. Economics are driven by "want".

Besides, I'm sure people have been saying similar things since the beginning of aviation. And even before that, with railroads.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineFlyboyOz From Australia, joined Nov 2000, 1985 posts, RR: 25
Reply 17, posted (2 years 8 months 2 weeks 11 hours ago) and read 8359 times:

I believe that those future aircraft would have the delta wings


The Spirit of AustraliAN - Longreach
User currently offlinebe77 From Canada, joined Nov 2007, 455 posts, RR: 0
Reply 18, posted (2 years 8 months 2 weeks 11 hours ago) and read 8352 times:

Quoting cosmofly (Reply 5):
Boeing can snap them together quickly like the F-82 Twin Mustang

Put some airfoil in between (more than just a wing carry through) and a lifting body starts to happen.
Either as a lifting body or as an F-82, it might not have the full theoretical efficiencies of a full on flying wing, but possibly likley easier to manage some of the day to day boring stuff like construction, aerodynamics, flight regimes and control laws in various failure modes, etc. And it would still would have proper window seats too  .

Of course, everyone thinks that Rutan's BiPod is simply a hybrid power, composite, flying car concept, but obviously it was another Scaled Composites R and D project, this time for either the B78787 or the A350350.

Last random thought - what would the span of a 78787 / 350350 twin fuselage style likely have to be? Could consider just joining two barrels (would look sort of like a sideways Stratocruiser or even a sideways A380) or spacing them a couple diameters apart. Regardless, it'd probably have a pretty wide span to get enough wing out here? Does anyone have the aero skills to ballpark a reasonable efficient wing dimension? Before commenting about the economics of one big barrel instead of two little ones, allow for the assumption that two little ones could be a lot less captial intensive in design, setup, and in manufacturing (Also lower risk if you are using proven technologies). Anyway, some random thoughts that aren't expected to go far  



Tower, Affirmitive, gear is down and welded
User currently offlinebe77 From Canada, joined Nov 2007, 455 posts, RR: 0
Reply 19, posted (2 years 8 months 2 weeks 11 hours ago) and read 8350 times:

Quoting cosmofly (Reply 5):
like the F-82 Twin Mustang

Oh, and is the lounge in the secondary fuselage going to be called 10 Forward?
Or, would you put in a cockpit mockup and sell fantasy camp seats (with unifroms and everything) to wannabe's  



Tower, Affirmitive, gear is down and welded
User currently offlineaerotech777 From United States of America, joined Aug 2009, 68 posts, RR: 0
Reply 20, posted (2 years 8 months 1 week 6 days 19 hours ago) and read 8151 times:

Quoting prebennorholm (Reply 6):
An A380 has 210 to 216 klb takeoff thrust with one engine shut down after V1. A twin A380 would need the same on each engine.

So the jump is almost 100% on top of the current GE90-115B.
Quoting Starlionblue (Reply 7):
Much more than that. You forgot engine out requirements.

The Trent 972 that Qantas uses has 72k lb (320kN) of thrust. With an engine out that's 216k lb (960kN) total from three engines. On a hypothetical 380 twin, you would need to get that thrust from ONE engine to handle an engine out. That's 87% more thrust than a GE-90.

Engine out requirements for twin are different than requirement for quad. For example the gradient of climb for twin (second take-off climb) is 2.4%, but for quad is 3%. After engine failure, A380 twin may need less thrust than the thrust you mentioned.

Twin A380 needs larger engine --> ground clearance is decreased -->Twin A380 may need longer landing gears


User currently offlineparapente From United Kingdom, joined Mar 2006, 1583 posts, RR: 10
Reply 21, posted (2 years 8 months 1 week 6 days 10 hours ago) and read 8037 times:

Well we 'know' what will come next (if anything) as both companies have shown us their thoughts and Boeing are (as we write) testing their second scale model varient.This is of course some flavour of BWB.The aerodynamic benefits are so huge.

From am engine standpoint however if you read the associated articles closely you will see where they are going.Certainly 'green' in terms of noise and polution but the other area that has been shown is the exact opposite of what is being discussed.Some concepts are shown with a series of smaller engines that (I think) help the overall aerodynamics and a 'blown wing'.It is outside mu knowledge but it is easy to find examples/drawings of these.So I guess it is more likley to go this way rather than build some sort of huge oversized engine for the BWB


User currently offlineacedriver From China, joined Nov 2011, 36 posts, RR: 0
Reply 22, posted (2 years 7 months 3 weeks 5 days 12 hours ago) and read 7093 times:

Twin engined A380 means something even more beastly than GE90 - ooh I would love to see that..
I imagine that the fan blade will be so large that the undercarriage must be extended to keep the nacelle from scraping on the ground..


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