patrickjp93
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Re: Future VLA Market?

Tue Jan 14, 2020 5:49 pm

Matt6461 wrote:
patrickjp93 wrote:
given those regions are expanding passenger loads on long haul far faster than Singapore or the Middle East 3, there is a trend toward larger jets than the A321XLR and B787 being needed. .


Again you need the barest amount of quantitative analysis. Take PVG: Per wikipedia, ~146 pax/movement. So the average aircraft at PVG is 737-800 or A320-sized. Traffic needs to roughly triple - absent any airfield improvement - until the average aircraft needs to be 777-9 sized.

Incorrect. You need both mean and median to do a worthwhile analysis on that. Plenty of wide bodies land there daily from overseas for business travel, and that WILL continue to increase. So regional traffic aside, given trunk routes are also growing constrained, what do we see in this affecting the VLA market future?
 
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Matt6461
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Re: Future VLA Market?

Tue Jan 14, 2020 5:57 pm

patrickjp93 wrote:
Matt6461 wrote:
patrickjp93 wrote:
given those regions are expanding passenger loads on long haul far faster than Singapore or the Middle East 3, there is a trend toward larger jets than the A321XLR and B787 being needed. .


Again you need the barest amount of quantitative analysis. Take PVG: Per wikipedia, ~146 pax/movement. So the average aircraft at PVG is 737-800 or A320-sized. Traffic needs to roughly triple - absent any airfield improvement - until the average aircraft needs to be 777-9 sized.

Incorrect. You need both mean and median to do a worthwhile analysis on that. Plenty of wide bodies land there daily from overseas for business travel, and that WILL continue to increase. So regional traffic aside, given trunk routes are also growing constrained,


Explain why the median tells us something dramatically more important than the mean.
Re overseas widebodies - what percentage of PVG's movements are they?

patrickjp93 wrote:
what do we see in this affecting the VLA market future?


What do YOU see? Please make an argument. So far you're just stating the obvious fact that traffic is increasing without making a direct logical connection between increasing traffic and a compelling need for 500pax/movement. Lots of smart people have tried this argument in the past (see Airbus 1990-2018); it didn't go well for them.
 
patrickjp93
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Re: Future VLA Market?

Tue Jan 14, 2020 6:02 pm

Matt6461 wrote:
patrickjp93 wrote:
Matt6461 wrote:

Again you need the barest amount of quantitative analysis. Take PVG: Per wikipedia, ~146 pax/movement. So the average aircraft at PVG is 737-800 or A320-sized. Traffic needs to roughly triple - absent any airfield improvement - until the average aircraft needs to be 777-9 sized.

Incorrect. You need both mean and median to do a worthwhile analysis on that. Plenty of wide bodies land there daily from overseas for business travel, and that WILL continue to increase. So regional traffic aside, given trunk routes are also growing constrained,


Explain why the median tells us something dramatically more important than the mean.
Re overseas widebodies - what percentage of PVG's movements are they?

patrickjp93 wrote:
what do we see in this affecting the VLA market future?


What do YOU see? Please make an argument. So far you're just stating the obvious fact that traffic is increasing without making a direct logical connection between increasing traffic and a compelling need for 500pax/movement.

I see someone either never took or barely scraped by in Statistics 101. Let's take a nice round number of 101 movements total, ordered from smallest to largest. The 51st is the median movement and its associated size. The sum of all seats in all the movements divided by the number of movements is the mean.

So you can have 50 50-seater jets, 1 100-seater jet, and another 50 350-seater jets. The median is 100. The mean is (2500+100+17500)/101 = 199.009...

Being told "the average" is one of the oldest tricks in the book of "lies, damn lies, and statistics."

As China and India develop and business travel overseas increases dramatically with their rising economies, the already-packed A350s flying for the big 3-4 government-owned airlines will no longer be enough as Hong Kong and PVG in particular run out of slots. HKG is at much lower risk of this as Hong Kong Airlines is likely to dissolve at this point, but PVG is getting fairly well constrained now.
 
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Matt6461
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Re: Future VLA Market?

Tue Jan 14, 2020 6:06 pm

patrickjp93 wrote:
Statistics 101


Yeah thanks for telling me the difference between median and mean.

I asked for an argument. You still have not made one. You're citing a "lies, damn lies" in the manner of a person who has seen one Youtube video.

Nor have you responded to the other poster who has told you how mistaken you are about aerodynamics.

You're digging in on ignorance, as I expected (though I had held out hope).

You have no logically-driven case for why the world needs a 500-seater, just open-ended statements about traffic increases and requests that other people do your thinking for you.
 
patrickjp93
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Re: Future VLA Market?

Tue Jan 14, 2020 6:08 pm

Matt6461 wrote:
patrickjp93 wrote:
Statistics 101


Yeah thanks for telling me the difference between median and mean.

I asked for an argument. You still have not made one.

Nor have you responded to the other poster who has told you how mistaken you are about aerodynamics.

You're digging in, as I expected (though I had held out hope).

You have no logically-driven case for why the world needs a 500-seater, just open-ended statements about traffic increases and requests that other people do your thinking for you.

I see you didn't remotely read my post. Try again. I made an argument specific to the Indian and Chinese markets on expanding business travel when the A350s for China and 787s for India are already packed to the damn gills. It's not like there are lots of slots available at LAX, SFO, ORD, IAH, DFW, JFK, EWR, and ATL, not to mention HKG and PVG, though HKG might be getting some with HKA looking ready to implode.
 
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Matt6461
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Re: Future VLA Market?

Tue Jan 14, 2020 6:17 pm

patrickjp93 wrote:
A350s for China and 787s for India are already packed to the damn gills


I stand corrected. You haven't made zero arguments; you've partially made at least one transparently stupid argument.
To complete this bad argument, your next step would be, "given that these [fish, apparently] have no gill-space remaining, China and India must buy larger planes and have no room simply to add more longhaul 787/A350 flights."

You see the problem with your argument, right?
Let me help you out: How many 777-9's do China and India expect to receive over the next five or so years of growth?
 
patrickjp93
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Re: Future VLA Market?

Tue Jan 14, 2020 6:23 pm

Matt6461 wrote:
patrickjp93 wrote:
A350s for China and 787s for India are already packed to the damn gills


I stand corrected. You haven't made zero arguments; you've partially made at least one transparently stupid argument.
To complete this bad argument, your next step would be, "given that these [fish, apparently] have no gill-space remaining, China and India must buy larger planes and have no room simply to add more longhaul 787/A350 flights."

You see the problem with your argument, right?
Let me help you out: How many 777-9's do China and India expect to receive over the next five or so years of growth?

Cathay Pacific will have 21 in all by 2024. The government-controlled airlines probably will avoid buying another american plane as long as they can after the MAX fiasco, and most of the world is waiting on EASA's word on the 777X since it's insisting on a joint certification this time. And the VLA market future, as I assume we'd all think, is most certainly a prospect long beyond 2025.

Also, did I not just say there is a shortage or outright lack of available slots at a lot of big hubs India and China would be flying to? LHR and AMS are full, CDG is almost full, and FRA is almost full too, to be inclusive of our European friends.

If I'm transparently stupid you really could use a mirror. And in accordance with the forum rules, you might want to cool your jets mon frere.
 
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Matt6461
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Re: Future VLA Market?

Tue Jan 14, 2020 6:33 pm

patrickjp93 wrote:
If I'm transparently stupid you really could use a mirror. And in accordance with the forum rules, you might want to cool your jets mon frere.


I've said nothing about you personally, only your argument. In fact, I've said that many very smart people made your bad argument during decades of A380 marketing. If I didn't have at least some hope that you're smart enough to realize you're making a bad argument, I wouldn't try.

most of the world is waiting on EASA's word on the 777X since it's insisting on a joint certification this time.


That's a possible defense to what I think is the obvious counterargument you need to address, but for your defense to work you'd have to show at least some evidence that airlines are chomping at the bit to order 777X but EASA/FAA just won't unleash the pent up demand. Is there any such evidence? Aside from EK, whose orders are dubious anyway, a small portion of 77W operators have ordered 779.

LHR and AMS are full, CDG is almost full, and FRA is almost full too


Same was true a couple years ago when they could have ordered gobs of cheap A380's to address this fullness. Yet it didn't happen. Despite all those very smart Airbus folks making the same exact argument over decades of fullness that you are making now. Have you at least pondered that fact?

And the VLA market future, as I assume we'd all think, is most certainly a prospect long beyond 2025.


Indeed. And I'm maybe the biggest VLA advocate on this entire forum.
I just think there are good and bad arguments for VLA's and I have seen the bad arguments damage VLA prospects for at least a generation. I'd rather see the industry not make the same mistake twice.
 
patrickjp93
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Re: Future VLA Market?

Tue Jan 14, 2020 7:43 pm

Matt6461 wrote:
patrickjp93 wrote:
If I'm transparently stupid you really could use a mirror. And in accordance with the forum rules, you might want to cool your jets mon frere.


I've said nothing about you personally, only your argument. In fact, I've said that many very smart people made your bad argument during decades of A380 marketing. If I didn't have at least some hope that you're smart enough to realize you're making a bad argument, I wouldn't try.

most of the world is waiting on EASA's word on the 777X since it's insisting on a joint certification this time.


That's a possible defense to what I think is the obvious counterargument you need to address, but for your defense to work you'd have to show at least some evidence that airlines are chomping at the bit to order 777X but EASA/FAA just won't unleash the pent up demand. Is there any such evidence? Aside from EK, whose orders are dubious anyway, a small portion of 77W operators have ordered 779.

LHR and AMS are full, CDG is almost full, and FRA is almost full too


Same was true a couple years ago when they could have ordered gobs of cheap A380's to address this fullness. Yet it didn't happen. Despite all those very smart Airbus folks making the same exact argument over decades of fullness that you are making now. Have you at least pondered that fact?

And the VLA market future, as I assume we'd all think, is most certainly a prospect long beyond 2025.


Indeed. And I'm maybe the biggest VLA advocate on this entire forum.
I just think there are good and bad arguments for VLA's and I have seen the bad arguments damage VLA prospects for at least a generation. I'd rather see the industry not make the same mistake twice.

As Boeing has stated previously, their belief is that the prospects of the 777X program improve over time. A lot of the 777-300ERs flying today are fairly young, and there are plenty of delivery slots open, so no one needs to rush to order it. Though I do have it on good authority Air Canada will place an order 10 or fewer in the next six months as long as CASA and EASA are happy with the 777X's compliance and progress on certification as the flight campaign begins.

LHR basically chipped away at NBs flying into it for the last 5 years and kept making more gate modifications for wide bodies. When a narrowbody can no longer land there, will that be enough for you to be convinced? BA almost exclusively flies A380, 747, A350, and 787-10 out of LHR these days. I don't see demand from New York, Chicago, and Atlanta reducing in the wake of Brexit, rather increasing, so those trunk route birds will also be under greater pressure. Luckily, BA has ordered the 777-9 to step in for the A350s where higher capacity is needed and in for the 747-8I as it retires.

The A380 also had specific technical problems such as reinforced runway requirements and F gates that even some trunk airports lacked or had no way of addressing. Those are where the 747-8 flies to since the A380 can't.
 
JustSomeDood
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Re: Future VLA Market?

Wed Jan 15, 2020 12:45 am

patrickjp93 wrote:
Matt6461 wrote:
patrickjp93 wrote:
A350s for China and 787s for India are already packed to the damn gills


I stand corrected. You haven't made zero arguments; you've partially made at least one transparently stupid argument.
To complete this bad argument, your next step would be, "given that these [fish, apparently] have no gill-space remaining, China and India must buy larger planes and have no room simply to add more longhaul 787/A350 flights."

You see the problem with your argument, right?
Let me help you out: How many 777-9's do China and India expect to receive over the next five or so years of growth?

Cathay Pacific will have 21 in all by 2024. The government-controlled airlines probably will avoid buying another american plane as long as they can after the MAX fiasco, and most of the world is waiting on EASA's word on the 777X since it's insisting on a joint certification this time. And the VLA market future, as I assume we'd all think, is most certainly a prospect long beyond 2025.

Also, did I not just say there is a shortage or outright lack of available slots at a lot of big hubs India and China would be flying to? LHR and AMS are full, CDG is almost full, and FRA is almost full too, to be inclusive of our European friends.

If I'm transparently stupid you really could use a mirror. And in accordance with the forum rules, you might want to cool your jets mon frere.


Long-haul routes flying to-and-from China have generally been loosing money for the airlines involved, with crap yields, over capacity and awful load factors being the norm. I don't see appetite to upguage these routes unless the route economics change, no matter what growth projections say.

India as an emerging market is also very, very price-sensitive, I reckon the growth in international air travel demand there will be better served by stuffing 370+ seats in A330s/787s rather than the premium + high-demand flying which is conducive to VLAs.
 
patrickjp93
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Re: Future VLA Market?

Wed Jan 15, 2020 1:04 am

JustSomeDood wrote:
patrickjp93 wrote:
Matt6461 wrote:

I stand corrected. You haven't made zero arguments; you've partially made at least one transparently stupid argument.
To complete this bad argument, your next step would be, "given that these [fish, apparently] have no gill-space remaining, China and India must buy larger planes and have no room simply to add more longhaul 787/A350 flights."

You see the problem with your argument, right?
Let me help you out: How many 777-9's do China and India expect to receive over the next five or so years of growth?

Cathay Pacific will have 21 in all by 2024. The government-controlled airlines probably will avoid buying another american plane as long as they can after the MAX fiasco, and most of the world is waiting on EASA's word on the 777X since it's insisting on a joint certification this time. And the VLA market future, as I assume we'd all think, is most certainly a prospect long beyond 2025.

Also, did I not just say there is a shortage or outright lack of available slots at a lot of big hubs India and China would be flying to? LHR and AMS are full, CDG is almost full, and FRA is almost full too, to be inclusive of our European friends.

If I'm transparently stupid you really could use a mirror. And in accordance with the forum rules, you might want to cool your jets mon frere.


Long-haul routes flying to-and-from China have generally been loosing money for the airlines involved, with crap yields, over capacity and awful load factors being the norm. I don't see appetite to upguage these routes unless the route economics change, no matter what growth projections say.

India as an emerging market is also very, very price-sensitive, I reckon the growth in international air travel demand there will be better served by stuffing 370+ seats in A330s/787s rather than the premium + high-demand flying which is conducive to VLAs.

from what historical data I can find, Chinese airlines have really only been losing money recently in the wake of Hong Kong and now Taiwan's mini rebellions.
 
JustSomeDood
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Re: Future VLA Market?

Wed Jan 15, 2020 1:40 am

patrickjp93 wrote:
JustSomeDood wrote:
patrickjp93 wrote:
Cathay Pacific will have 21 in all by 2024. The government-controlled airlines probably will avoid buying another american plane as long as they can after the MAX fiasco, and most of the world is waiting on EASA's word on the 777X since it's insisting on a joint certification this time. And the VLA market future, as I assume we'd all think, is most certainly a prospect long beyond 2025.

Also, did I not just say there is a shortage or outright lack of available slots at a lot of big hubs India and China would be flying to? LHR and AMS are full, CDG is almost full, and FRA is almost full too, to be inclusive of our European friends.

If I'm transparently stupid you really could use a mirror. And in accordance with the forum rules, you might want to cool your jets mon frere.


Long-haul routes flying to-and-from China have generally been loosing money for the airlines involved, with crap yields, over capacity and awful load factors being the norm. I don't see appetite to upguage these routes unless the route economics change, no matter what growth projections say.

India as an emerging market is also very, very price-sensitive, I reckon the growth in international air travel demand there will be better served by stuffing 370+ seats in A330s/787s rather than the premium + high-demand flying which is conducive to VLAs.

from what historical data I can find, Chinese airlines have really only been losing money recently in the wake of Hong Kong and now Taiwan's mini rebellions.


Chinese Airlines haven't lost money as a whole, but their international routes sure have been loosing money for a good while https://www.airliners.net/forum/viewtopic.php?f=3&t=1434035&hilit=Zoedyn. That figure is after the substantial local subsidies that airlines may receive to open such routes.

Its no better for foreign carriers as well, witness AA taking an axe to nearly every TPAC route ex-Chicago, United ending a ton of their routes to second-tier Chinese cities, and Delta outsourcing a lot of their Asia flying to KE. The shine has worn off the China growth story and airlines are adjusting as a result.
 
patrickjp93
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Re: Future VLA Market?

Wed Jan 15, 2020 12:39 pm

JustSomeDood wrote:
patrickjp93 wrote:
JustSomeDood wrote:

Long-haul routes flying to-and-from China have generally been loosing money for the airlines involved, with crap yields, over capacity and awful load factors being the norm. I don't see appetite to upguage these routes unless the route economics change, no matter what growth projections say.

India as an emerging market is also very, very price-sensitive, I reckon the growth in international air travel demand there will be better served by stuffing 370+ seats in A330s/787s rather than the premium + high-demand flying which is conducive to VLAs.

from what historical data I can find, Chinese airlines have really only been losing money recently in the wake of Hong Kong and now Taiwan's mini rebellions.


Chinese Airlines haven't lost money as a whole, but their international routes sure have been loosing money for a good while https://www.airliners.net/forum/viewtopic.php?f=3&t=1434035&hilit=Zoedyn. That figure is after the substantial local subsidies that airlines may receive to open such routes.

Its no better for foreign carriers as well, witness AA taking an axe to nearly every TPAC route ex-Chicago, United ending a ton of their routes to second-tier Chinese cities, and Delta outsourcing a lot of their Asia flying to KE. The shine has worn off the China growth story and airlines are adjusting as a result.

Well subsidizing an industry long-term never works out well. CX being able to run BNE-KHG-JFK for $1350 AUD vs. the 1850+ for BNE-LAX/YVR-(PHL/JFK)/EWR couldn't hold up for long.

AA not being able to compete with JAL, Fiji, Thai, and Philippine airlines isn't surprising either, and United is probably being charged hefty fees at secondary Chinese cities to make it easier for chinese airlines to compete.
 
LH707330
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Re: Future VLA Market?

Fri Jan 17, 2020 5:11 am

Matt6461 wrote:
LH707330 wrote:
My guess is that practical considerations like maintenance, etc. kill the business case, even if the math were to work out a few % better.


I can totally see that being the case; I'm not convinced either. To be convinced, I'd need a squad of engineers, accountants, and management analysts, as would any CEO reviewing this proposal. I'm just putting up an idea whose detailed analysis I haven't seen analyzed elsewhere. I'd love to read about it if you've seen it analyzed elsewhere...

I can see several factors changing the calculus from the the '90's, if in fact such a proposal was seriously considered back then:

1. Power by the Hour contracts in today's marketplace make the maintenance of different types more manageable. An OEM could write a PBH contract for just the smaller engine or, more likely, tie such a PBH agreement into a marketing pitch for an airline's broader fleet that would, presumably, include many of the smaller engines mounted on NB's.
2. Technology burden, especially the economic preponderance of LLP's, has increased since the 90's. Whereas most maintenance used to be spent on labor, it's now spent on LLP's. Because this proposal involves a positive delta to labor mx expense and negative delta to LLP mx expense, the landscape may be different.

To know whether "maintenance etc." would outweigh the couple % performance benefit, we'd need to know something about the maintenance delta. Any idea on how to estimate that? Frankly I don't have such an idea, but I can't see it how it'd be huge. For four identical engines you need, say 20 mx personnel, for two pair of different engines, do you 25 personnel? Even if (1) the disparate pair is 10% lower in total thrust than would be the quadruplets and (2) the smaller engines are universal types like PW1100 or LEAP? I would expect the PW1100/LEAP mx expense being significantly lower, per lb-T, than the quadruplets. You have the LLP factor plus the sheer scale of NB engine mx infrastructure. That would mean you'd need a significant management/other delta for the administrative complexity added.

It's not like the OEM's are incapable of missing things or of making huge mistakes (see, e.g., MAX and A380).

Well, what if the quadruplets were the cheap engines? Around 2006, Airbus had started testing the GTF, so it's not completely out of the ordinary that they would have considered a 340neo back then. How big was PBH back then? The single-source on the OEO is one of the main things that killed the 340-300 from an acquisition cost standpoint against the three-engine choice 777, so giving the idea another go with engine choices would have been under consideration. I speculated about that in this thread: viewtopic.php?f=5&t=1435995 I'd be curious to get your thoughts on the back-of-the-napkin 340neo, but that's getting slightly OT.

I've not looked into the concept of the two-pair quad more myself, hence the speculation about it. If you look at this article, it suggests 10-20% of DOC is engines. If you make that more complex and add 1 pp to save 1% in fuel, you're probably going backward. Then there's a scale effect: by the same argument that two different engine types in a fleet maxes sense above X units, you could notionally make the same point about the two-pair idea, you just need a fleet of X for it to make sense, provided of course that it has an advantage. Now it's trickier to lease out, etc.

Where's Lightsaber, I'd be curious for his take on the topic.
 
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Matt6461
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Re: Future VLA Market?

Mon Jan 20, 2020 5:55 am

LH707330 wrote:
Well, what if the quadruplets were the cheap engines?


Could totally change the equation, especially if there weren't somewhat "off-the-shelf" larger and smaller engines.

LH707330 wrote:
If you look at this article, it suggests 10-20% of DOC is engines. If you make that more complex and add 1 pp to save 1% in fuel, you're probably going backward.


I scanned the article but not sure what "10-20% of DOC" means. Is that cost of engine purchase and mx? Engine's contributions to fuel burn (through parasite drag and weight)? Engine's knock-on effects on overall frame size/expense, compared to a towed glider?

I'm sure it doesn't include not the towed glider comparative hypo, but unless an analysis accounts for the system-level impact of my proposal's claimed (from first principles only) negative delta to fin size, it would be incomplete.

Re complexity - this might be repeating myself but we have to disaggregate administrative and technical complexity. Compared to a normal quad, the proposal should reduce technical complexity: you have to mount/fuel/maintain four engines regardless and I'm just turning two of those engines into simpler, more robust NB types rather than the fine-tuned thoroughbreds mounted on WB's. On the tech side, there should be less complexity. Administratively, yes, it's more complex. But with the shift from labor to LLP within the mx cost burden (a shift that wasn't as marked for the 717 discussed in your doc, btw), the administrative/labor issues are less salient. Engine mx in total doesn't exceed 10% of DOC, afaics. Given a 2:1 ratio of parts to labor/admin within engine mx (~3% DOC for labor), you'd need a transformative adminstrative quandary for my layout to cause a 1% DOC delta.

LH70730 wrote:
Where's Lightsaber, I'd be curious for his take on the topic.


IIRC I've pushed this proposal at him a couple times and he either thinks it's too dumb for his time or has responded and I'm too dumb to understand. :)
 
GalaxyFlyer
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Re: Future VLA Market?

Mon Jan 20, 2020 3:18 pm

Fine, how would your design comply with FAR 121.193 which says,

2) Its weight, according to the two-engine inoperative, en route, net flight path data in the Airplane Flight Manual, allows the airplane to fly from the point where the two engines are assumed to fail simultaneously to an airport that meets the requirements of §121.197, with the net flight path (considering the ambient temperatures anticipated along the track) clearing vertically by at least 2,000 feet all terrain and obstructions within five statute miles (4.34 nautical miles) on each side of the intended track. For the purposes of this subparagraph, it is assumed that—

(i) The two engines fail at the most critical point en route;


(ii) The net flight path has a positive slope at 1,500 feet above the airport where the landing is assumed to be made after the engines fail;


(iii) Fuel jettisoning will be approved if the certificate holder shows that the crew is properly instructed, that the training program is adequate, and that all other precautions are taken to ensure a safe procedure;


(iv) The airplane's weight at the point where the two engines are assumed to fail provides enough fuel to continue to the airport, to arrive at an altitude of at least 1,500 feet directly over the airport, and thereafter to fly for 15 minutes at cruise power or thrust, or both; and


So, the two “big thoroughbreds” die and the two NB engines are all the design has to meet the enroute standard.
 
asr0dzjq
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Re: Future VLA Market?

Mon Jan 20, 2020 4:01 pm

blacksoviet wrote:
The technology exists for a trijet with the same capacity as the 747-8.

Take the engines from the 77W [and] make the fuselage [6 metres] longer and a couple [centimetres] wider than the 779. This will allow comfortable ten-abreast seating. Add a third engine in the tail and you have a 748 trijet with even longer range. This could cover the very top of the market for 35 years. After that, the technology might exist for a 748 twinjet with 9000 miles nautical range.

A trijet could serve as a stopgap for the VLA market, offering even greater range than the 779.

One day after we are all gone, there may be a twinjet that can fly 500 passengers in four classes, against headwinds halfway around the world from a hot and high airport. The engine technology simply does not exist at this time.

Would the third engine be straight tube or S-duct?
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blacksoviet
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Re: Future VLA Market?

Mon Jan 20, 2020 8:02 pm

asr0dzjq wrote:
blacksoviet wrote:
The technology exists for a trijet with the same capacity as the 747-8.

Take the engines from the 77W [and] make the fuselage [6 metres] longer and a couple [centimetres] wider than the 779. This will allow comfortable ten-abreast seating. Add a third engine in the tail and you have a 748 trijet with even longer range. This could cover the very top of the market for 35 years. After that, the technology might exist for a 748 twinjet with 9000 miles nautical range.

A trijet could serve as a stopgap for the VLA market, offering even greater range than the 779.

One day after we are all gone, there may be a twinjet that can fly 500 passengers in four classes, against headwinds halfway around the world from a hot and high airport. The engine technology simply does not exist at this time.

Would the third engine be straight tube or S-duct?

Probably s-duct for improved aerodynamics. Imagine a giant L-1011.
 
GalaxyFlyer
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Re: Future VLA Market?

Mon Jan 20, 2020 8:10 pm

Like that was so successful.
 
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Matt6461
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Re: Future VLA Market?

Tue Jan 21, 2020 1:22 am

GalaxyFlyer wrote:
Fine, how would your design comply with FAR 121.193 which says,

2) Its weight, according to the two-engine inoperative, en route, net flight path data in the Airplane Flight Manual, allows the airplane to fly from the point where the two engines are assumed to fail simultaneously to an airport that meets the requirements of §121.197, with the net flight path (considering the ambient temperatures anticipated along the track) clearing vertically by at least 2,000 feet all terrain and obstructions within five statute miles (4.34 nautical miles) on each side of the intended track. For the purposes of this subparagraph, it is assumed that—

(i) The two engines fail at the most critical point en route;


(ii) The net flight path has a positive slope at 1,500 feet above the airport where the landing is assumed to be made after the engines fail;


(iii) Fuel jettisoning will be approved if the certificate holder shows that the crew is properly instructed, that the training program is adequate, and that all other precautions are taken to ensure a safe procedure;


(iv) The airplane's weight at the point where the two engines are assumed to fail provides enough fuel to continue to the airport, to arrive at an altitude of at least 1,500 feet directly over the airport, and thereafter to fly for 15 minutes at cruise power or thrust, or both; and


So, the two “big thoroughbreds” die and the two NB engines are all the design has to meet the enroute standard.


First of all, there's no logical/policy/safety reason this plane couldn't be certified according to ETOPS standards. I.e. you treat it for regulatory purposes as if it's a twin-engine plane for which the loss of both engines is catastrophic in many cases. That may not be possible under current regulations but neither was extended ETOPS until Boeing pushed for certification. A/B have immense influence over regulators (for good and bad reasons); were they to develop this kind of plane there's no logical reason that regulators should refuse to certify it under twin-engine standards, merely because there are two other engines besides the big twins. Compliance with ETOPS standards would impose some additional mx burden but, as is obvious from the popularity of twins and ETOPS, the industry has judged this burden not to be prohibitive.

I'm really not interested in hearing any objections to changing the regulations based solely on "those aren't the current regulations." Obviously that's so, but I have some professional and personal experience with the administrative state and how it responds to arguments/pressure; I believe Boeing/Airbus could quite easily certify a mixed quad under regulations no more stringent than existing twin and ETOPS regulations.

An ETOPS twin with two extra engines is safer than an ETOPS twin - which is pretty safe already.

In addition to the particular case examined in this post, the second-segment climb gradient standard for quads could/should also be reexamined were my proposal adopted. I don't understand why quads/tris face a higher gradient in the first place - it's not like there's any difference between twin/tri/quad planes hitting a building. Anyone know why the different standard?

---------------------------------
Even under current regulations, meeting the standard seems feasible. The issue is whether there's enough thrust to cruise at a given altitude and/or enough thrust to allow a shallow-sloped descent from normal cruising altitude without hitting something. For this problem, let's look at 15,000ft. That implies limitations for flying over the Andes or Himalayas, but such limitations already impact most planes (flights regularly have to go around the Himalayas, for example).

The necessary thrust is determined by [gross weight] / [L/D ratio] for the critical case.

What's the gross weight of the plane? I'd expect a good 2027-30 VLA to be slightly smaller than an A380 in floor area, much smaller in fuselage, wing, empennage, and engine size/weight. Its MTOW shouldn't exceed 800k lbs. 3-4% of that would be burned off during climb, so gross weight at the earliest possible critical failure is ~770k lbs.

What's L/D? At cruise it should be at least 24, at max endurance or max L/D speed (slightly slower), it should be 25-26.
Using 25 L/D, drag at critical case is 30.8k lbs [770,000 / 25], let's say 30k lbs given a slightly higher L/D.

So the smaller engines need to give 30k lbs-T combined for level flight at 15k feet altitude.

Now let's reverse-engineer how powerful those engines must be to meet the foregoing condition:

At 15,000ft, air density is 63% of sea level density. http://www.aerospaceweb.org/design/scripts/atmosphere/
Thrust lapse for engines is not quite linear with air density, so let's say our NB engines at 15k feet can supply 65% of their sea level thrust.
Next we have to consider "ram drag" or thrust lapse due to speed for our critical case.
As mentioned above, speed during the critical case would be around max L/D speed, not max range speed - slower than cruise. Let's say 300kn TAS.
For two 35k SLS-thrust engines to give sufficient power in my critical case, ram drag at 300kn would have to be around 34% [ (.66 * .65 * 70 ~= 30)].
That seems feasible. For the GE9X, for example, ram drag at M=.85 is ~45%. http://i298.photobucket.com/albums/mm26 ... c5d334.jpg
[calculated using atmospheric density at 20k feet and assigning to ram drag the remainder of thrust fall-off from 100k to 30k]

Our critical case is much slower than .85M and our NB engine is far less propulsively efficient at max thrust than GE9X, meaning less proportional ram drag [i.e. the fan spins much faster than GE9X in RPM and engine exhaust speed, which would be inefficient for cruise but is acceptable for emergency and takeoff cases].
To give a complete answer regarding how much thrust the NB engines need for my critical case would require more details about the engines than I have, but I'm satisfied that this analysis at least shows the feasibility of the planned configuration under current regulations.
 
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Matt6461
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Re: Future VLA Market?

Tue Jan 21, 2020 1:28 am

blacksoviet wrote:
asr0dzjq wrote:
blacksoviet wrote:
The technology exists for a trijet with the same capacity as the 747-8.

Take the engines from the 77W [and] make the fuselage [6 metres] longer and a couple [centimetres] wider than the 779. This will allow comfortable ten-abreast seating. Add a third engine in the tail and you have a 748 trijet with even longer range. This could cover the very top of the market for 35 years. After that, the technology might exist for a 748 twinjet with 9000 miles nautical range.

A trijet could serve as a stopgap for the VLA market, offering even greater range than the 779.

One day after we are all gone, there may be a twinjet that can fly 500 passengers in four classes, against headwinds halfway around the world from a hot and high airport. The engine technology simply does not exist at this time.

Would the third engine be straight tube or S-duct?

Probably s-duct for improved aerodynamics. Imagine a giant L-1011.


There's no good reason to consider a conventional tri-engine today. The old ones existed simply due to existing engine options.
A tri-engine shifts bending-relieving weight into bending-causing weight.
It increases bending weight of the fuselage, which in turn means more wing bending weight (or a shorter fuselage for equal weight).
It adds maintenance complexity that is not counterbalanced by any efficiency rationale.*

*ok there's some diminution of tailfin size due to lower OEI yaw moment but that doesn't begin to counterbalance the drawbacks
 
blacksoviet
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Re: Future VLA Market?

Tue Jan 21, 2020 2:38 am

Matt6461 wrote:
blacksoviet wrote:
asr0dzjq wrote:
Would the third engine be straight tube or S-duct?

Probably s-duct for improved aerodynamics. Imagine a giant L-1011.


There's no good reason to consider a conventional tri-engine today. The old ones existed simply due to existing engine options.
A tri-engine shifts bending-relieving weight into bending-causing weight.
It increases bending weight of the fuselage, which in turn means more wing bending weight (or a shorter fuselage for equal weight).
It adds maintenance complexity that is not counterbalanced by any efficiency rationale.*

*ok there's some diminution of tailfin size due to lower OEI yaw moment but that doesn't begin to counterbalance the drawbacks

The point is that there are no engine options today for a twinjet with the 748s capacity. If you were to build a plane that size tomorrow, you would have to have at least three engines. The question is whether the decreased fuel consumption of a trijet makes up for the poor aerodynamics compared to a quad jet.
 
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Matt6461
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Re: Future VLA Market?

Tue Jan 21, 2020 3:20 am

blacksoviet wrote:
The question is whether the decreased fuel consumption of a trijet makes up for the poor aerodynamics compared to a quad jet.


You're begging the question by assuming as a premise something you need to prove as part of your argument.
First you need to establish that there is, in fact, decreased fuel consumption attributable to a trijet vs. a quad.
I have given you several reasons that is not the case. Are you not aware of the importance of bending relief in wing design, and of the impact of bending stress on fuselage design? If not, there's plenty of Google-able material. If you are aware, you need to explain why the increases of those weight factors are somehow outweighed by the other factors.

blacksoviet wrote:
The point is that there are no engine options today for a twinjet with the 748s capacity.


This is also something you just assume without any proof. Like have you even considered the aero-structural design of the 748 compared to a late-2020's plane? There is no way it would weigh anything close to the 748, or require anything close to its engine thrust. This is like assuming that the NMA needs as much thrust as the 707 because they're similar capacity/range. That's not a smart way to think about airplanes. The physics depends on things like weight, aerodynamics, and engine efficiency far more than the simple seatcount and range.
 
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Matt6461
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Re: Future VLA Market?

Tue Jan 21, 2020 3:57 am

Bjorn Fehrm's Fundamentals of Airliners, Part 6, has a good interview illustrating my rationale for the mixed-engine quad proposal:

let’s start with the question we put to CFM through their director of Strategic Communication, Jamie Jewell.

In Power Points around the LEAP, it is described as having lower overall pressure ratio than GEnx-1. It would mean lower static takeoff ratio than 47 (which is the ICAO Annex 16 ratio you give for the highest revving GEnx-1). Is this correct?
A: Narrowbody aircraft have different design objectives than widebody aircraft because of high cyclic operation, which can be up to 6-8 flights per day. The expectation for LEAP is 20,000 cycles on wing, first run, in order to achieve low maintenance cost. The message of the chart is that the cycle design and temperatures for LEAP have been selected for the right balance of performance and operating cost. High cycle temperatures resulting from high operating pressure ratio could drive down time on wing and increase maintenance cost.


https://leehamnews.com/2015/01/19/funda ... he-engine/

As stated by CFM, it designed the LEAP to have lower OPR (thus lower thermal efficiency) than the GEnx-1. Just as I have been saying in this thread, the NB engine intentionally trades some fuel efficiency for better mx costs in a high-cycle environment. Incidentally, lower operating temperatures also mean less advanced materials in the core and therefore lower initial production/purchase cost.

The fuel efficiency sacrificed is on the order of only a few percent, which is why the tradeoff is worth it despite the fact that fuel is a much bigger portion of operating cost than engine mx.

Now consider the application of this dynamic to a mixed-engine quad:
  • Let's suppose the Big:Small ratio of engine thrust is 2:1 (e.g. a 60k big engine and a 30k NB engine).
  • Assume the SFC delta between the two engines is 3%.
  • Next let's assume that, in cruise, we run the big engine at 90% of max thrust and the small engine at 30% of max thrust (which should still be close to the "cruise bucket" in which SFC remains relatively constant with RPM as a percentage of max RPM).
  • Under those parameters, the smaller engine is contributing only 1/7 of the engine thrust.
  • Given that the smaller engine has 3% higher SFC, the cruise SFC delta due to the smaller engine is only 0.4%.

That's a very small delta that might be counterbalanced already by the following fact:
-versus a uniform quad, the "big" engine is 33% larger than the uniform engines. If we're talking ~180k total thrust, a 60k engine's economies of scale vs. a 45k engines (lower trip clearance losses etc.) may already cancel out the cruise SFC delta attributable to the smaller engine.

But we haven't yet discussed the main benefits:

Tailfin size reduction

For a quad, the tailfin is typically sized according to the OEI yaw moment contributed by the outboard engine. Under my proposal, the size of the outer engines shrinks by, say 1/3, which should enable something like a 1/3-smaller tailfin (assuming other critical conditions don't intervene).
On the A380 - and probably any VLA - the tailfin is disproportionately large: ~7% of wetted area (Swet). http://www.dept.aoe.vt.edu/~mason/Mason ... Berger.pdf

So a ~30% reduction of tailfin area saves >2% of Swet and on the order of 1% of OEW.

Less engine wetted area and weight per lb-T for the smaller engines

The next generation of aircraft are going to pay a significant - though still justified - price in engine drag for the next-gen engines like Ultrafan. A 70k Ultrafan, for example, will use a 140in fan. https://aviationweek.com/air-transport/ ... 47-testbed
Compared to Trent 1000's 118in fan, that implies >50% greater Swet and drag for equal thrust.
In that scenario, engines would account for ~20% of total airplane parasitic drag (Dp).

While the drag penalty is worth it for engines that provide all of your cruising power, my proposal would allow offloading excess engine power (i.e. power not needed to maintain cruise) to the smaller engines, whose less-efficient power would come with a much lower Dp penalty.

If 33% of engine power comes with 33% less drag, that's ~11% less engine Dp or a >2% delta to total Dp. Of course using an older-tech engine would mean a higher SFC delta but we can divide its impact by 7 as outlined above. The drag-SFC tradeoff (inclusive of tailfin effect) would be neutral even if SFC delta increased to 15%, leaving a much bigger delta to engine mx and acquisition cost. Where that "tradeoff between tradeoffs" regarding fuel vs. mx and acquisition would be optimal is a matter of detailed design.

Plus the smaller engines will weigh less, per lb-T, than uniform quad engines or the larger engines. Why? Because they're thrust-bumped for higher ratio of thrust to dry weight (T/W) ratio than would be an optimal cruising engine.
The sweet spot for modern engines is ~5 T/W. Within engine families there's variation, but the larger thrust-bumped variants always face penalties in SFC and mx cost for higher T/W (unless additional tech intervenes, as RR claims it got the TXWB-97 to SFC parity with the weaker versions via additional tech).

Because the smaller engines will be at least 6 T/W instead of 5, you'll save a couple thousand pounds of OEW inclusive of pylons (engine dry weight is ~60% of propulsion system weight).

----------------------------

If a ~2028 VLA used PIP'd LEAP/PW1100 small engines, I'd expect the deltas versus Ultrafan, per lb-T, to be as follows:
  • -30% acquisition cost
  • -30% cost of life-limited parts (LLP)
  • -35% Swet/Dp
  • +10% cruise SFC

Combining these parameters into a DOC accounting, we have the following building blocks:

Fuel efficiency:
  • >2% delta to Dp from a smaller tailfin = >1% delta to L/D
  • -1% delta to OEW from smaller tailfin
  • -2.5% delta to Dp from the NB engines = ~2.5% delta to L/D
  • -0.5% OEW from the NB engines
  • +10% SFC for the smaller engines, contibuting +1.5% SFC at plane-level

Combining these factors in a terribly rough way (post is already long enough), we get ~4% lower trip fuel burn.

Acquisition cost:
  • If 1/3 of engine cost is 30% lower, we get -11% delta to engine acquisition cost.
  • If engines are 1/3 of plane acquisition cost, we get ~3.5% lower plane acquisition cost

Maintenance:
  • Similar to acquisition cost, a -11% delta to LLP cost
  • If engine mx is 2/3 LLP cost, that's -7% engine mx delta
  • some positive delta to engine personnel/administration cost for mixed types, can't say what. It would have to be a 14% delta to negate the LLP delta under these parameters.
  • OTOH, the NB engines used are ubiquitous so their personnel cost might be lower than for Ultrafan-gen widebody engines

Now to sum up the DOC costs, let's say fuel, acquisition, and engine mx are 40, 25, and 10% of DOC respectively. Given -4%, -3.5%, and -7% delta to the respective DOC components, my proposal would give approximately -3% DOC delta.

That's before incorporating the added complexity of mixed-engine maintenance, but for that factor to negate 3% DOC would require a doubling of total engine labor-related costs and would require the NB-engine-specific costs to be about six times as high as normal. I can't even see those costs being twice as high as normal, so I'm pretty convinced that the proposal would pencil out if my aero-structural and acquisition cost estimates are in the ballpark.

-----------------

A concluding note about why this proposal might be something for a late-2020's quad but not an earlier one:

The proposal works largely because of the very high price - in acquisition, maintenance (LLP's), and drag - of Ultrafan-gen engines. Absent the 30% deltas between Ultrafan-tech and older tech for these factors, the proposal would rely only on the tailfin delta and probably wouldn't be worth the OEM's design effort even if it conferred a <1% DOC advantage. Future planes will be facing increasingly large non-fuel tradeoffs for Ultrafan-level fuel efficiency; a proposal such as mine is the only way to avoid these tradeoffs as it's the only way partially to avoid using Ultrafan-level engine technology: A twin or uniform quad can't afford to sacrifice 10% engine SFC to avoid Ultrafan drag and other costs; only a plane that cruises primarily with Ultrafan and takes off with more help from older/cheaper engines can partially ameliorate the coming fuel/other cost dynamics.
 
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Matt6461
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Re: Future VLA Market?

Tue Jan 21, 2020 4:25 am

OK another note on why this proposal is VLA-specific.

The first and most obvious reason is that only a large plane is likely to be a quad in today's environment.

The less obvious reason relates to a VLA's drag composition: A double-decker economizes on parasitic drag via having less fuselage wetted area per passenger. It does not, however, have any intrinsic advantage regarding induced drag - that's largely a matter of aspect ratio. We can see this dynamic with the A380: whereas Dp usually predominates in modern airliners, Di predominates for the A380 in cruise. http://i298.photobucket.com/albums/mm26 ... 1fb33c.jpg

Why does this matter?

Because Di also predominates for all airliners - all flying things - at lower speeds, especially takeoff. Engine thrust is usually dictated by takeoff requirements and therefore is usually dictated by Di parameters. At cruise speeds, however, Di typically becomes less important while Dp increases exponentially and dominates overall drag.

As a result of a (double-decker) VLA's weight-relative economy on Dp, it is more likely to have excess thrust in cruise than would a normal airliner.
Therefore, it has room for its engines to operate at a lower percentage of maximum possible thrust than would a normal airliner.
A 737 in cruise, for example, is still running at ~90% of its maximum thrust. There's therefore little room to implement my proposal, as you'd need to run all engines at close to maximum power and therefore would bear the full price of a smaller engine's SFC loss.

I would note also that this proposal probably couldn't be implemented on the current A380. Although it's pretty good on Dp per passenger, its wing is so bad - i.e. Di is so high because of its low AR - that I doubt the A380 has much room to spool down a theoretical pair of less-efficient engines in cruise.
 
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DarkSnowyNight
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Re: Future VLA Market?

Tue Jan 21, 2020 4:36 am

blacksoviet wrote:
The point is that there are no engine options today for a twinjet with the 748s capacity. If you were to build a plane that size tomorrow, you would have to have at least three engines. The question is whether the decreased fuel consumption of a trijet makes up for the poor aerodynamics compared to a quad jet.



There are none in production, no. But with any competent OEM, there would be an assigned Power Plant program to address that need.

And as for decreased fuel consumption, that will not likely be what you think. It is worth noting that 77Ws now burn to within about 12% of what an A346 does, and more than an A343. A set of three GE-9Xs would almost certainly out-burn the four GENX-2B67s 748s now use. The size and related output on an engine matter as much as the number of them when talking about fuel consumption.

A 748 sized (capacity WRT both PAX & F models) aircraft would not likely look, or be configured like what we see now with the out-going quad engined design. It would very likely be weight reduced on the order of fifteen percent or more OEW. It is worth noting that though the 748 essentially got a new wing, it is not still as light as what we expect with the more modern, super-critical* designs. As well, deleting two engines removes a lot of structure, and as importantly, required wing area.

A future VLA, of 748 capacity, will very likely be a 777 derivative. It is a mature, well known platform with an excellent record. Though it can probably only be stretched to about 110% the capacity of a 748 before it is too cost prohibitive to make one safe, that will still be more than adequate for the needs of the coming decades.

We will scope out incremental gains in Power Plant efficiencies, but there is not a lot of low-hanging fruit left. Commercial Aircraft are as much subject to the Tyranny of Convergent Evolution as anything else. Barring a major sea-change (One that OEMs and Operators would want to see happen), the next generation VLAs are already here in the forms of the 779 & A35K.




* as in Supercritical by design, rather than having self-same features added.
"Ya Can't Win, Rocky! There's no Oxygen on Mars!"
"Yeah? That means there's no Oxygen for him Neither..."
 
Sokes
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Re: Future VLA Market?

Tue Jan 21, 2020 5:19 am

My favorite topic again: Should planes be built for airports or airports built for planes?

Human psychology seems to obsess with the biggest, fastest, best...
There was a time in Germany high speed trains would drive above 200 km/h outside of cities. Close to the cities they had to slow to 60 km/h or so as railroad switches were not changed yet. Why not change them first and drive with 160 km/h max?
80 km/ 240 km/h = 20 min
20 km/ 60 km/h = 20 min
or:
80 km/ 160 km/h = 30 min
20 km/ 100 km/h = 12 min

Similar how can a change of long range planes solve congestion at airports? I believe the desire for maximums interferes with reasoning.

The success of Turkish and Emirates indicates that labor costs, be it flight attendants or people working at the airport, matters. Otherwise why would somebody fly US to India via Arabian Gulf instead of Europe?

2+2 business direct flights in narrow-bodies for frequency and economy tickets over cheap labor cost hubs may be the future. As unfreedom in the air regulates number of flight movements and not passengers, I wouldn't be surprised if in 15 years some airlines would like to order combined a few hundred VLA.
Otherwise why would an airline fly A380 from Arabian Gulf to Europe?

We don't know if there will be tax on aviation fuel and when geared engines become available to make a more reasonable MTOW VLA.

lightsaber wrote:

Ironically, the A388 wasn't large enough. The main deck should have been 11-across and it should have been longer. The weight/space of the two stairs, elevators (people and carts), and added wiring/plumbing requires more scale for efficiency.
...
The next VLA must be far more efficient than smaller aircraft, the A380 wasn't enough more efficient.



+1. I may add that engines were not advanced enough, at least not for the range Airbus aimed at.
Why can't the world be a little bit more autistic?
 
FGITD
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Re: Future VLA Market?

Tue Jan 21, 2020 7:38 am

GalaxyFlyer wrote:
Like that was so successful.


One of my favorite things about these threads is the disparity between this site and reality.

Yes, we shall tail mount a ge90...because that design worked on the 1011 and therefore will now.

Folks can Roll out all that statistics and studies they want, but for the time being there are only 2 relevant parties to this discussion. Airlines and manufacturers.

Are the airlines requesting or ordering any of the aircraft ideas in this thread? No

Are the manufactures designing and selling any of the aircraft ideas in this thread? No
 
Sokes
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Re: Future VLA Market?

Tue Jan 21, 2020 11:59 am

FGITD wrote:
One of my favorite things about these threads is the disparity between this site and reality.

Yes, we shall tail mount a ge90...because that design worked on the 1011 and therefore will now.

Folks can Roll out all that statistics and studies they want, but for the time being there are only 2 relevant parties to this discussion. Airlines and manufacturers.

Are the airlines requesting or ordering any of the aircraft ideas in this thread? No

Are the manufactures designing and selling any of the aircraft ideas in this thread? No


So why are you wasting time in social media?
Why can't the world be a little bit more autistic?
 
FGITD
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Re: Future VLA Market?

Tue Jan 21, 2020 3:15 pm

Sokes wrote:
FGITD wrote:
One of my favorite things about these threads is the disparity between this site and reality.

Yes, we shall tail mount a ge90...because that design worked on the 1011 and therefore will now.

Folks can Roll out all that statistics and studies they want, but for the time being there are only 2 relevant parties to this discussion. Airlines and manufacturers.

Are the airlines requesting or ordering any of the aircraft ideas in this thread? No

Are the manufactures designing and selling any of the aircraft ideas in this thread? No


So why are you wasting time in social media?


I enjoy these forums, I've met some excellent people, and learned a great deal through those with more years in the industry than I have. There is a wealth of knowledge on this site, and indeed even in this thread. Some very interesting thoughts regarding the future of VLA.

However then you have some who harp on about sticking a ge90 in the tail of a 777, asking why there's no 747-200neo and making outrageous statements.

It works to dissuade those with actual interest and knowledge
 
Sokes
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Re: Future VLA Market?

Tue Jan 21, 2020 4:03 pm

FGITD wrote:

However then you have some who harp on about sticking a ge90 in the tail of a 777, asking why there's no 747-200neo and making outrageous statements.

It works to dissuade those with actual interest and knowledge


Aviation is a topic that attracts a lot of enthusiasts, including myself.
We have a lot of wrong assumptions. Obviously the site profits from pilots and engineers who have more knowledge. You can mention that the third engine is difficult to maintain and that weight so far from the wings is not good. I think I learned it here in an earlier topic.

So why is there no 747-200 Neo? (Just a joke.)
Why can't the world be a little bit more autistic?
 
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Matt6461
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Re: Future VLA Market?

Tue Jan 21, 2020 9:17 pm

FGITD wrote:
However then you have some who harp on about sticking a ge90 in the tail of a 777, asking why there's no 747-200neo and making outrageous statements.

It works to dissuade those with actual interest and knowledge


I don't mind people posting outrageous ideas because one has to have a certain level of knowledge before knowing what's outrageous. I'm fine with posts from curious people at the start of their aviation journey posting here. My first posts were outrageous, I learned, and eventually joined the industry myself.

What I do mind is folks who post any ideas - outrageous or not - and then refuse to listen/learn when those ideas are challenged. There's been a bit of that in this thread.

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