While it's not going to happen...not even remotely ... but as a thought experiment... If someone think they have too much money and dunped their money into making such a plane... what would be the capability and economic of such a plane? How much cheaper than 330/350 it need to be in order to attract airlines getting and using it? Is there some niche that would be conquered by such design? Unmatchable hot and high performance?

That was the original plan sort of. However the engines were not ready in time so they picked A320-class ones.

I'd rather like to see a A345 with Trent 1000 TENs.

lightsaber wrote:

How to beat the economics of the B789 ot A359... Impossible. Small engines are less efficient than large as there is more surface area to flow path. Due to blade tip leakage, the pressure ratio is lower. Plus, it is just more weight.

A dream, but no leasing company will touch a quad right now.

Lightsaber

And Airbus has switched wing tooling for the A330 line to eliminate the common A340 outboard engine pylons, so the return on investment would be problematic to say the least.

If just as a thought experiment for 346 and 345 series with low hours, I'd think it might be moderately interesting as a thought experiment with upgauged gtf engines for cargo carriers. The frames would be basically/comparatively free. Airbus is practically a non player in cargo so again it's just a fun thought experiment for low hour/low cycle conversions on a message board.

Depending on how well GTF gear box scales up(reliability etc.), it might be more efficient to use 4 smaller GTF powerplant versus two large conventional twin spool ones

Slug71 wrote:

I'd rather like to see a A345 with Trent 1000 TENs.

So would Boeing for the 787

LDRA wrote:

Depending on how well GTF gear box scales up(reliability etc.), it might be more efficient to use 4 smaller GTF powerplant versus two large conventional twin spool ones

Probably not as member lightsaber was alluding too above. By all accounts the larger the engine, the more efficient
it should be. I`m looking forward to RR`s proposed GTF, which coupled to the Advance core promises class leading
fuel savings. There is the small matter of designing there own take on such a gearbox ( sharing design & risk with
Liebherr ) but such is their respective skills, it would be nice to see them reach market in a few years without too
many problems & offer a super efficient power plant to match a new super efficient aircraft ( MOM or downsized
787/350 ). As others have said, 4-hollers are done, with the exception IMHO of an A380Neo, but even then most
would rubbish the notion.

[code][/code]

LDRA wrote:

Depending on how well GTF gear box scales up(reliability etc.), it might be more efficient to use 4 smaller GTF powerplant versus two large conventional twin spool ones

Doubt it when they have to cough up for the cost of the two extra engines and their related financing/maintenance!

Well, I don't think such a plane could match the economic of latest fresh design twins either, but I think it would be interesting to know how far such design would be behind

c933103 wrote:

Well, I don't think such a plane could match the economic of latest fresh design twins either, but I think it would be interesting to know how far such design would be behind

The answer would be "too far to make any sense"

c933103 wrote:

Well, I don't think such a plane could match the economic of latest fresh design twins either, but I think it would be interesting to know how far such design would be behind

How much would a used A340-300 cost, probably less than $20m 4x $4m for GTF engines so you would have a re-engined "refreshed" A340-300 for approx $36m, a new B789 is going to cost north of $200m. You can buy an awful lot of gas for $160m.

I think the economics work if you can get somebody to bankroll development.

We used to have CFM re-engined DC-8s and it is wonderful to see old but still viable airframes receive a new lease of life.

In this day and age, it would be far more costly to re-engine and certify an old A343/345/346. If it was something that is viable, wouldn't some company have already done up the proposals? The easy availability of old A330s sort of killed off any demand there may be for a A340neo.

Spacepope wrote:

lightsaber wrote:

How to beat the economics of the B789 ot A359... Impossible. Small engines are less efficient than large as there is more surface area to flow path. Due to blade tip leakage, the pressure ratio is lower. Plus, it is just more weight.

A dream, but no leasing company will touch a quad right now.

Lightsaber

And Airbus has switched wing tooling for the A330 line to eliminate the common A340 outboard engine pylons, so the return on investment would be problematic to say the least.

I thought that the A330 MRTT's wing had a common structure with A340-200/-300? The mounting locations and provision for fuel piping for the A340's outboard engines is used for the wing refuelling pods.



I think it is highly unlikely that we ever will see a new four-engine turbofan civil pax aircraft again. If each PW GTF engine had less that half the weight of the RR Trent 7000, had less than half the drag, had half the purchase price and cost less than half to maintain, and had higher reliability than the RR Trent 7000, there might be a slight chance. But, it's nowhere close.

reidar76 wrote:

Spacepope wrote:

lightsaber wrote:

How to beat the economics of the B789 ot A359... Impossible. Small engines are less efficient than large as there is more surface area to flow path. Due to blade tip leakage, the pressure ratio is lower. Plus, it is just more weight.

A dream, but no leasing company will touch a quad right now.

Lightsaber

And Airbus has switched wing tooling for the A330 line to eliminate the common A340 outboard engine pylons, so the return on investment would be problematic to say the least.

I thought that the A330 MRTT's wing had a common structure with A340-200/-300? The mounting locations and provision for fuel piping for the A340's outboard engines is used for the wing refuelling pods.

This was my recollection too and reports at the time of the RAF purchase confirm this so a set of A340 wingset tooling must remain, what Airbus probably mean is the standard A330 wing has eliminated the extra piping etc.

http://www.airforce-technology.com/projects/a330_200/

All the aircraft will be capable of being fitted with two Cobham FRL 900E Mark 32B refuelling pods, one under each wing. Some aircraft will receive a third centreline underbelly refuelling system. The A330-200 wing shares the same design structure, including the strengthened mounting points, as that of the four-engine A340 aircraft. The wing positions for mounting the air-to-air refuelling pods therefore require minimal modification.

How much less fuel would a 34,000lb GTF burn compared with the current CFM56s?
Also, how much less fuel does the A359 consume compared to the current A343?

A pipedream, but I'd love to see if the numbers even remotely stack up.

Pacific wrote:

How much less fuel would a 34,000lb GTF burn compared with the current CFM56s?
Also, how much less fuel does the A359 consume compared to the current A343?

A pipedream, but I'd love to see if the numbers even remotely stack up.

I don't have figures off-hand for the 343 but the 359 burns about the same per hour as a 40 ton lighter 333. The difference 359 to 343 at the same weight should be in the same ballpark as 359 to 333 at the same weight. I'll make a WAG at one ton an hour or more.

Important additional factor: The 359 does M0.85 comfortably while the 343 cruises around M0.82. In other words you're burning less per hour and on top of that you're flying for a shorter time..

Bottom line: The numbers don't even remotely stack up.

And of course it's not only about fuel consumption but about maintenance cost. A quad has more engines, more pumps, more piping, etc to keep running.

Starlionblue wrote:

Pacific wrote:

How much less fuel would a 34,000lb GTF burn compared with the current CFM56s?
Also, how much less fuel does the A359 consume compared to the current A343?

A pipedream, but I'd love to see if the numbers even remotely stack up.

I don't have figures off-hand for the 343 but the 359 burns about the same per hour as a 40 ton lighter 333. The difference 359 to 343 at the same weight should be in the same ballpark as 359 to 333 at the same weight. I'll make a WAG at one ton an hour or more.

Important additional factor: The 359 does M0.85 comfortably while the 343 cruises around M0.82. In other words you're burning less per hour and on top of that you're flying for a shorter time..

Bottom line: The numbers don't even remotely stack up.

And of course it's not only about fuel consumption but about maintenance cost. A quad has more engines, more pumps, more piping, etc to keep running.

Its not going to be competeing against the A359 but the 77E. P&W was aiming for a 15% advantage from V2500 which was within +-1% of the CFM56 so the engines should make a significant improvement in economics.

BoeingVista wrote:

Starlionblue wrote:

Pacific wrote:

How much less fuel would a 34,000lb GTF burn compared with the current CFM56s?
Also, how much less fuel does the A359 consume compared to the current A343?

A pipedream, but I'd love to see if the numbers even remotely stack up.

I don't have figures off-hand for the 343 but the 359 burns about the same per hour as a 40 ton lighter 333. The difference 359 to 343 at the same weight should be in the same ballpark as 359 to 333 at the same weight. I'll make a WAG at one ton an hour or more.

Important additional factor: The 359 does M0.85 comfortably while the 343 cruises around M0.82. In other words you're burning less per hour and on top of that you're flying for a shorter time..

Bottom line: The numbers don't even remotely stack up.

And of course it's not only about fuel consumption but about maintenance cost. A quad has more engines, more pumps, more piping, etc to keep running.

Its not going to be competeing against the A359 but the 77E. P&W was aiming for a 15% advantage from V2500 which was within +-1% of the CFM56 so the engines should make a significant improvement in economics.

77E is the 777-200ER, right? Sure, if you're talking re-engine of the 343, but the 777-200ER is 20 years old. It is not very competitive at this point, and airlines might be better served with a new 787-9 or 350-900 or perhaps even a 330neo.

Starlionblue wrote:

77E is the 777-200ER, right? Sure, if you're talking re-engine of the 343, but the 777-200ER is 20 years old. It is not very competitive at this point, and airlines might be better served with a new 787-9 or 350-900 or perhaps even a 330neo.

Ok so, let me be clear I cannot see any rational to build new A343's, none. However re-engining a frame that still has a lot of life in it may be viable as the capital cost could be $160m - $200m less than buying a new 787-9 and that is a whole shit load of a difference in capital.

BoeingVista wrote:

Starlionblue wrote:

77E is the 777-200ER, right? Sure, if you're talking re-engine of the 343, but the 777-200ER is 20 years old. It is not very competitive at this point, and airlines might be better served with a new 787-9 or 350-900 or perhaps even a 330neo.

Ok so, let me be clear I cannot see any rational to build new A343's, none. However re-engining a frame that still has a lot of life in it may be viable as the capital cost could be $160m - $200m less than buying a new 787-9 and that is a whole shit load of a difference in capital.

Fair point. However the cost of re-engining would not be insignificant.

I used some numbers from wiki and used the difference between MTOW and OWE and then 100kg per pax for standard capacity to get a rough guess of fuel per pax km at max marketing range (i know its crude).

Then I assumed that the GTF would be 15% lower sfc than the CFM so I reduced the fuel burn accordingly and what do you know! they are within a percent.

I know its crude but why would we expect anything different.

2 decades old aluminium jet re-engined with state of the art engines beng very close to a modern plastic airliner showing that the better economics of a modern airlier are buried mostly in the engines.

Your guess it to work out whether the last statement was about this mythical A340GTF vs A350 or the A330neo vs 787.........

Fred

I think a 4 engine GTF version of the proposed 263 ft 777-10 might be viable. I say this because the optimal GTF bypass ratio for a ~110k+ engine could require a fan diameter as large as 150+ inches, likely too big for even the 777 without major gear height changes. Four 50k optimal BPR geared turbofans (maybe 100 inches or so) might end up being as or more efficient overall...

I'd love to see a 343neo, but it ain't gonna happen. Couple things to consider with this idea:
1. A 343neo is the only possible one, because it's got good weight properties, while a 345/346 would be too heavy
2. The 5C is about 3% better than the 5A, so figure the GTF is somewhere in the neighborhood of 13% better than the 5C
3. The GTF is ~5 years newer than the T7000 in technology, while the CFM56-5C was about 5 years older than the T700
4. The 343 burns 5-10% more than a 333 on a similar mission
5. The 330neo has a 2-4% fuel burn penalty vs a 789

Baking all of those together, a GTF 343 would claw back some of #4 due to #3 (relative engine quality), thus ending up in the 0-5% worse category (ballpark) versus a 333neo. That would put it 2-7% behind a 789, and a few more points behind a 350. If one could get the engines cheap (mass market), it could possibly work strictly from a fuel burn standpoint, but two things would sink it for sure:

1. The feedstock of newish 340s (post-2000 builds) is not big enough to cover the costs of certification
2. You could probably find used 332s for less money if you wanted to do it on the cheap

Spacepope wrote:

And Airbus has switched wing tooling for the A330 line to eliminate the common A340 outboard engine pylons, so the return on investment would be problematic to say the least.

I think most people misunderstand the difference between the 330/340 wing. They are not the same wing, around 95% similar. There is no outer pylon mount on the A330, that is only built into the A340 wing. The inner pylon mount on the A330 is very different to the A340 as the weight of the engine is a lot greater, as well as the thrust.

The advantage the A330 had in the tanker role is they had made provisions in the A330/A340 design to get hydraulics, fuel, and electrical to/from the outer pods. That pathway had already been certified for engine burst, bird strike, lightning, and ice.

They have been able to use this routing to get the services to the hose units on the wing. The A330 tankers do undergo structural modification in order to mount the hose drum units, there is no bolt holes sitting there from the A340, no fuel pipes, no electrical runs.

BoeingVista wrote:

How much would a used A340-300 cost, probably less than $20m 4x $4m for GTF engines so you would have a re-engined "refreshed" A340-300 for approx $36m, a new B789 is going to cost north of $200m.

Prob looking at 10-15 million per GTF.

zeke wrote:

BoeingVista wrote:

How much would a used A340-300 cost, probably less than $20m 4x $4m for GTF engines so you would have a re-engined "refreshed" A340-300 for approx $36m, a new B789 is going to cost north of $200m.

Prob looking at 10-15 million per GTF.

I came across an article that said GTF production costs were currently $12m per unit but needed to get down to $4m, cant lay my hands on it at the moment.

BoeingVista wrote:

I came across an article that said GTF production costs were currently $12m per unit but needed to get down to $4m, cant lay my hands on it at the moment.

You would need to buy more than the engine, everything below the wing, pylon, cowl, reverser, accessories etc. Then the cost of modifications. The DC-8 modifications in the last 1970s cost around 15 million per aircraft, that is around 50 million in today's money.

What if they made an A340-700 with six engines?

Another thing is that, if you're re-engining old 340 instead of acquiring new 787/350s, how much time can those reengined plane remain flying?

c933103 wrote:

Another thing is that, if you're re-engining old 340 instead of acquiring new 787/350s, how much time can those reengined plane remain flying?

The answer to that question would be to look at the DC-8 Super 70 series... So a reasonably long time I would think.

SCAT15F wrote:

c933103 wrote:

Another thing is that, if you're re-engining old 340 instead of acquiring new 787/350s, how much time can those reengined plane remain flying?

The answer to that question would be to look at the DC-8 Super 70 series... So a reasonably long time I would think.

I don't know if DC8 is more a outliner or a standard among airliners...

Wacker1000 wrote:

What if they made an A340-700 with six engines?

And while you're at it, make a DC-7 with jet engines