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Matt6461
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Re: 2025ish A380-900NEO

Sun Mar 18, 2018 9:24 pm

Matt6461 wrote:
-4k-lbs drag delta from default is ~2% of OEI thrust [ 4 / (.8*260) ]


I made a mistake by measuring against total thrust rather than OEI thrust. Vstab drag delta (default-->uneven) is 33% higher (4 / (.8*3*65)) = minus ~2.6%. All in, a net less of ~.4% kinetic energy versus default takeoff run. Would imply ~.4% lower MTOW if we were aiming for field performance improvement over A388 versus efficiency improvement. Given -900NEO's operating environment and low tire speeds, ~1% trip cost improvement seems far wiser than ~.4% more MTOW from constrained runways (rare for A380 - in high places its low tire speeds enable full payload/range, would be even more true of lighter-wing-loaded -900NEO).
 
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Re: 2025ish A380-900NEO

Mon Mar 19, 2018 9:07 am

Eurofusion wrote:
Is this an accurate model of the current A380 hold area?


Page 2 of Chapter 2-6 of the ACAP gives the actual belly dimensions. http://www.airbus.com/content/dam/corpo ... c-2016.pdf. For our -900NEO just add the stretch dimensions (~15fore / 16aft with changed CoG?).

Eurofusion wrote:
In part you could argue this technology could be cascaded, so not entirely an A380NEO programme burden.


Yep and I think this is where larger jets are headed. When A and B competed for what became the SQ 777-9 order, both pitched stretches (-10 and -2000) that put galleys/lavs in the belly. It's a bit more efficient on the A380 because a single galley, well-located, can distribute to two levels. Also stairs to the belly can combine with UD stairs whereas they cost ~6 seats on A340.

Eurofusion wrote:
However certification might only allow that any trolley in a cabin must be able to be stored safely within 60ft on a flat plane.


I don't know of any such regulation. Can you explain a little more and/or give a citation? Obviously this would throw a wrench in some of our ideas.

Eurofusion wrote:
I think compartment 2 is this best candidate for the extended passenger area


Emirates may distinguish differently but physically there's only forward and aft belly holds. I was thinking aft is best for galley/lavs/amenities because it's easier to maintain CoG balance, especially with a tailcone or maindeck cargo hold.

What Emirates calls "compartment 3" would be best for a galley, with lifts at the very front, thus most central to the cabin and capable of distribution of trolleys throughout it. Lots of options though, including using only part of fore and aft bellies. That means another pair of stairs though.
 
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Re: 2025ish A380-900NEO

Mon Mar 19, 2018 10:12 am

"You got a ref for the A340 bulkhead? That's the first I've heard of it."

The A340NG got a new rear pressure bulkhead : vacuum infusion stitched CFRP form piece.
( continued on A380 and from the same people produced for the 787.)
https://www.compositesworld.com/article ... osite-part
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Re: 2025ish A380-900NEO

Mon Mar 19, 2018 2:49 pm


The A380-850


Image

Nacelles: similar diameter; thrust reduction similar to bypass increase. Nacelles shortened for reduced surface area/drag. Engines are still lighter because of shorter nacelles and lighter core.

Empennage size: -15%

Wing area: -15%

Effective wingspan (A380plus style scimiters): +7%

Total wetted area strongly reduced despite 2.8m stretch, by reduction in empennage, wing and nacelle surface. Smaller total wetted area and distribution of wetted area to revenue generating fuselage strongly improves economics.



The A380-850 specifications:


Image



The A380Mk2 vs. The CEO and the 777x:


Image


So I adjusted the table to the correct data (777x) from Leeham. I've haven't had the time yet to redo the aero modeling. I will also have to study Bjorn's latest three articles on drag to learn more on the drag implications over an average mission.

Although with this corrected data from Leeham the gap has decreased to my previous calculation we still see that if we compare the A380-850 vs. 777-9 and the A380CEO vs. 777-3 the fuel economy situation has improved 14% in favor of the A380. A significant gap that would change the competitive balance between the A380 and the 777.
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Matt6461
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Re: 2025ish A380-900NEO

Tue Mar 20, 2018 2:46 am

Taxi45 wrote:
The A380Mk2 vs. The CEO and the 777x:


We'd need, at least, OEW's and L/D's to evaluate your projections.
 
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Re: 2025ish A380-900NEO

Tue Mar 20, 2018 8:24 am

Matt6461 wrote:
Taxi45 wrote:
The A380Mk2 vs. The CEO and the 777x:


We'd need, at least, OEW's and L/D's to evaluate your projections.


Still working on the house so time restricted (and knowledge and tools), but OEW would be ~262.4t.

Aero will take more time. Perhaps next week.
Innovation is seeing opportunity before obstacle.
 
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Re: 2025ish A380-900NEO

Thu Mar 22, 2018 9:00 am

Here's the surface area delta's I've used:


Fuselage (2,78m stretch): +67,6m2

Wing area (-15%): -127m2

Winglets: +12m2

Empennage (-15%): -99m2

4 Engines (120" fan diameter, nacelle length -15%): -13,2m2


Total: -159,6m2



As you've pointed out earlier in the thread reduced MTOW of a smaller stretch makes integrating ultrafan type bypass ratios (there's no free lunch folks) into an A380mk2 design much easier. At 120'' fan diameter they would only be 4''/0.1m larger than the current Trent 900. Together with the new wing and the shorter nacelles I suspect that is easy doable.
Innovation is seeing opportunity before obstacle.
 
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Re: 2025ish A380-900NEO

Thu Mar 22, 2018 5:00 pm

One other point I've made earlier and now seems to start to sink in with people; this thrust class of engine with ultrafan type bypass ratios is one that can be more easily integrated into designs than any of the large twins can. If a 75k engine is 140" imagine the fan diameter on an ultrafan type 777....

That's one reason it's a good idea to wait for an ultrafan type engine for the A380mk2. Unlike with advance, it allows it go places (engine wise) where the large twins can't easily follow.
Innovation is seeing opportunity before obstacle.
 
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Re: 2025ish A380-900NEO

Sat Mar 24, 2018 8:26 am

Taxi645 wrote:
Total: -159,6m2


~4% Swet reduction and 7% span increase implies ~10% higher L/D.
Assuming -850 range @605pax = -800 rang @525 pax, and assuming 17% lower SFC (Ultrafan? Or are you using Advance?), then solving for OEW, we get:

-OEW = ~593,000lbs (23,000lbs delta from A388's 616,000lbs)
-Max-pax/bags trip fuel delta = -30% versus A388.

IMO there is no conceivable business case for such a plane. Yes, it will see more orders than A388 and yes, it will produce a profit stream. But would it recover ~$10bn investment? Almost certainly no at any reasonable discount rate. You'd want to see at least $3.5bn annual profit stream to justify the risk/cost/time horizon of this investment; even if you sold 50 -850's/yr you'd need $70mn per frame in profit. That would massively increase acquisition cost for airlines, hampering your ability to sell 50 or even 30/year.

The good news is that your performance estimate is far, far too conservative. Your wing/empennage/engine/LG projections are too conservative, and your 593k-lbs OEW is too high even for your conservative approach: -15% delta to wing, LG, empennage, and engine weight should save you another ~50k lbs. Then you run another loop on your wing area, empennage, engine, LG, and some fuselage.

I've modeled this before. Have you at least looked at my threads on A380X and A380NWO? They're written with less knowledge than I have now, but still ballpark valid, IMO. With ~2026 engines and a new wing, you should get close to 50% less fuel/pax vs. A388. Seriously. And that's without any stretch.

I'd still love to see a completely new wing on the A380. I remain convinced it would destroy the 777-9 by coming within ~10-15% of -9's trip cost with over 50% more capacity. I just think it would cost up to $10bn and produce a product significantly inferior to a clean sheet, slightly-smaller VLA. Airbus can't afford a ~2026 VLA that Boeing undercuts a few years later (remember - the 777-9 is dead in this scenario, Airbus has proven the VLA market, Boeing has to compete). That's A340NG all over again, with a much bigger writeoff.

For ~2021 EIS, an A380X would have given Airbus about a decade of highly-profitable monopoly. I urged that approach in 2014; that ship has sailed.
An A380-900NEO can deliver* nearly-equivalent per-seat economics for much lower development cost of ~$4bn.

*assuming we can (1) add enormous winglets, (2) do UD/MD sidewall sculpting, (3) do the tailcone cargo compartment, (4) shrink empennage as I project - there may different constraints, and (5) fit a ~62k Ultrafan under the wing - pretty sure we can.

Taxi645 wrote:
if we compare the A380-850 vs. 777-9 and the A380CEO vs. 777-3 the fuel economy situation has improved 14% in favor of the A380.


This goes back to my point about your conservative estimates. You'd do much better than 14% better fuel delta over 777-9, and would need to do so. Ask yourself: Had the A380 EIS'd with 14% lower fuel burn, would it have been a successful program? I think not. It would have sold more frames, sure. But we're talking ~5-6% lower total trip cost delta, surely not enough to (1) sell A380's for significant profit margin and (2) sell enough at that margin to recoup $15bn investment. You need at least $4bn profit stream, 50/year means you need $80mn profit per plane, which means ~30% higher sales price, which largely wipes out a 14% fuel delta.

To really make a VLA business case, you have to show efficiencies that would (1) enable undercutting any competition on price and/or (2) enable game-changing extra comfort (~50% more space/pax). Only then can you attract fliers to the megahub system needed to support hundreds of A380's.

The good news is that's possible - 2-decker is intrinsically more efficient than 1-decker. The bad news is your stretch/NWO doesn't get there.

So I've now devoted some attention to your proposals. In this very thread I've suggested how to improve them multiple times. Please do me the favor of considering my past rewing proposals before posting more about yours in this thread.
 
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Re: 2025ish A380-900NEO

Sat Mar 24, 2018 9:37 am

Matt6461 wrote:



I love what you are trying to do, and would like to participate in this discussion more, but given the figures quoted that appears to require a thorough database of existing aircraft data and dimensions (SWet, Span, fuselage surface area... etc), I do recall you posting a spreadsheet with all that data once, would you mind sharing it here?
 
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Re: 2025ish A380-900NEO

Sun Mar 25, 2018 6:33 am

@JustSomeDood

You might be thinking of Ferpe spreadsheet that I've referenced a few times:
Image

CAVEAT:

Ferpe's spreadsheet contains a very significant "oops" error: He forgot to double wing and empennage exposed area for total Swet. You can tell this from A380's fuselage Swet + 2 * A380 Wing Exposed Area = 2984m2, which is more than Ferpe's total A380 Swet.
Engines add another ~320m2, empennage another ~630m2 (=90% of one wing). Now we're close to 4,000m2 Swet.
I don't know how or whether Ferpe calculated the belly fairings contribution to Swet; IIRC a rough calc by yours truly estimated ~60m2 delta over the fuselage for belly fairing. That puts us right over 4,000m2.

Other sources also place A380 Swet at ~4,000m2:
http://www.dept.aoe.vt.edu/~mason/Mason ... Berger.pdf (page 2)
http://www.dept.aoe.vt.edu/~mason/Mason_f/A380Simon.pdf (page 7)

Further note: Just look at the A380's FuselageSwet/Cabin-area ratio compared to other planes: only 16.8% more fuselage for 52% more cabin area vs. 777-9. I know I harp on this again and again, but it never ceases to amaze and dismay me that Airbus squandered that game-changing advantage and produced such a dud of an airplane. How could half of the world's most brilliant technical minds manage to screw this up?
 
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Re: 2025ish A380-900NEO

Sun Mar 25, 2018 7:30 am

Matt6461 wrote:
How could half of the world's most brilliant technical minds manage to screw this up?


In such cases it's mostly not the technical minds doing the screw ups.
Innovation is seeing opportunity before obstacle.
 
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Re: 2025ish A380-900NEO

Sun Mar 25, 2018 8:17 am

Taxi645 wrote:
Matt6461 wrote:
How could half of the world's most brilliant technical minds manage to screw this up?


In such cases it's mostly not the technical minds doing the screw ups.


Of course. Not brilliant technical minds, anyways. It's the politically-astute, usually mediocre technical minds who elbow up the corporate ladder.
 
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Re: 2025ish A380-900NEO

Fri Mar 30, 2018 6:53 pm

I'll keep this thread going with conclusions and eventually a full economic analysis of the -900NEO.
On a parallel track, and maybe in a separate thread (?), I'd like to return to the rewinged A380NWO.
I haven't looked at NWO in a few years because, as I've said in this thread, it seems vulnerable to its own success: by 2030 its fuselage will be an old and suboptimal design; its success would kill the 777-9; a technically feasible response by Boeing/COMAC could torpedo A380NWO business case.

A few insights/developments have me reconsidering that position:

  • NMA's new engines now project at 45-50k, making them suitable for A380NWO with no or slight stretch.
  • The physical space for tailcone cargo/bags compartment alleviates A380's fuselage suboptimality. NWO would, like -900NEO, massively shrink the empennage, producing a large usable space in the tailcone.
  • A380NWO would see ~50% lower fuel/pax than A388 and lower mx, en route, and production costs (higher sales price though). At normal utilization, capital cost returns to dominance over fuel. Airbus might, therefore, preempt a Boeing/COMAC VLA via acquisition cost competition or the threat thereof. Airbus' threat would be credible because (1) a relatively low-volume VLA program needs high profit margin to recover development, (2) Airbus' development cost on NWO would be sunk cost in the future, making its price-cutting response optimal and credible, (3) it is ambiguous whether a clean-sheet VLA could be so much better than NWO that a ~25% higher sales price/seat would be justified.

Whether the -900NEO or NWO makes sense depends on their economics, as well as the likely economics of a competitive response. So now we have at least three planes to model: -900NEO, NWO, and future VLA.

So maybe a different thread for A380NWO (v4)? Or just it keep it all here?
 
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Re: 2025ish A380-900NEO

Thu Apr 05, 2018 7:44 pm

Slow to respond to a task previously mentioned in this thread. It involved building an approximate model of the proposed 900NEO/NWO I'm not an engineer so forgive the clumsy rendition but it's broadly based on the numbers - the wing profile however is a stab in the dark, forgive the pun. The nose has been redesigned in the vain of the A350 curved windscreens, so a cosmetic and efficiency double whammy.

The 3D model really is going to be the basis to demonstrate operational advantages of the re-designated belly space. An additional premium area, lavs and galley. However, most importantly a method to swap the trolley service whilst the main cabins are being cleaned and prepared. This will probably end up being an animation or click by stage animation. So anyway if there are any major show stopping comments to this profile let me know.

Image
 
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Re: 2025ish A380-900NEO

Thu Apr 05, 2018 11:47 pm

@Eurofusion that's a gorgeous rendering, thanks!

My only concern is it might be too gorgeous: It looks like the nose is reshaped? Or is it just the windshield? I don't see a NEO or NWO program materially changing the nose. Maybe the aesthetics of the windshield via highlighting but otherwise I'd have trouble seeing the ROI.

Re the 3D modelling - specifically of the galley - that'd be fantastic! I will post, within a few days, an embarrassingly crude schematic of a proposed belly layout reconciled to an optimal door layout that places lifts to coincide with exit rows on UD and MD. We can discuss our ideas for the layout here or via PM.

On that subject, I'm pretty sure our optimal layout will include a forward UD door and eliminate the front stairs completely or least shrink them.
 
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Re: 2025ish A380-900NEO

Fri Apr 06, 2018 1:25 am

@Matt6461, actually on a response way back there was talk of lifting the cockpit creating more space on the MD which you see here + the curved windscreen. It happened to make it's way into my 2D schematics published earlier in this thread which was the blueprint for this model. Sadly I agree in a plucking-a-figure-from-the-air kind'a way that the ROI probably wouldn't justify the development. The aerodynamic gain even compounded by additional storage space might not loosening the purse strings but it's a better looking plane for it. I'll revert it back to the existing nose.

I look forward to your sketches on the cargo area. I can work that up so don't worry about that. Obviously a top hinged cargo door might not work for the trolley service area as a standard catering truck may not be able to get close enough? Would we need to make an onboard extendable gangway contraption to compensate?
 
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Re: 2025ish A380-900NEO

Fri Apr 06, 2018 3:20 am

Here's a very crude layout of the -900NEO with belly galley and lavs:

EDIT: The scale of this diagram is inches, with the MD center at y=0 and MD door 2 at x=0. The MD compartment that contains "1800" is the tailcone baggage compartment that frees up belly space for galley/lavs/bar/rest.

Image

This scheme has space for ~120 galley unstacked carts: ~40 on deck and ~80 in the belly.

Belly Layout

The forward, 8.5ft-wide section of the belly contains 2 rows of 3ab carts oriented horizontally. That leaves a ~2.3ft aisle, allowing carts to pass each other.
The forward section is ~32ft long, meaning 11-12 rows at 6ab, plus a furthest-forward row of 8ab (70+ carts). 4 positions would be taken by 2 double-wide lifts, each of which could service UD and MD. But carts can be stowed in lifts for the first meal.

This main belly galley could have double-stacked portions, wherein the lifts could stop above the first rack and deliver empty carts for convenient stowage and/or board full carts stowed on the "upper shelf." Creating upper shelf space for, say, 30 carts would allow the lifts to stow empty carts and lift full carts in one trip without disrupting the flow of operations on the belly galley's main floor. After, say, 30 empty carts had been stowed on the upper shelf, sufficient room in the belly floor stowage slots would be open to smoothly move subsequent empty carts into positions vacated by on-deck carts. Even with 30 upper shelf stowage positions, over half of the belly remains free for ovens, coffee makers, and other meal-prep space.

Behind the forward section is an aisle and 2-abreast lavatories for J pax seated on MD. I put 8 in all, each 5.5' x 4ft, leaving a ~3ft aisle. That's a lot of space for lavatories but being conservative for now. So we've spent 16ft of the ~42ft of full-width aft belly (assuming 15ft rear stretch).

The remaining ~26ft of aft belly would contain:

  • the catering door - ~9ft wide and fronted by an 8-cart galley out the rear of which catering cart exchange would occur. During flight, this area would be for cart stowage and would otherwise function as part of the bar.
  • Bar for premium pax - potentially very large, but tradeable for other amenities.
  • Crew rest area
  • Stairs
  • whatever else fits

Passenger Decks Layout

The cabin consists or ~400 basic Y seats, ~240 PY/Y+ seats, and ~130 flat-bed J suites, ~50 of which have been specified as 4ab, ~62in pitch "Super J" or "Executive Suites."
Basic Y is at the front and divided between MD and UD so that each uses one door to board/deplane in about the time of CS300. The second doors on UD and MD have been moved as far aft as possible to cram high-density seating in front of them and premium seating behind them.
PY/Y+ is on the UD behind basic Y. With ~220-240 seats, it would be the critical boarding path flow. At only ~110-120 pax/aisle, its pax exchange time should be lower than A320's. Fewer seats can be specified of course.
J and Super J have the entire MD behind M2 (~40% of cabin area). These ~130 seats deplane through M2 are not the critical path for turnaround time.

Total pax seating is ~770 in this scheme.

For short turnaround time on quick hops like JFK-BOS, SFO-LAX, HKG-TPE etc., this plane would not require catering, as it could store several legs of provisions in the belly. TRT should be better than an A320 provided 4 jet bridges.

For longer missions, TRT would be reduced by removing the conflict between passengers and catering via an efficient and faster cart exchange via the belly catering door. Per the A388's ACAP, for example, catering the MD is the critical path for TRT.

As you can see from my bad drawing, there are 4 on-deck galleys. Each of these contains space for only a single meal service.
The largest two galleys sit directly above the belly galley and exchange carts with it directly via lifts between meals.
The two forward galleys each contain only ~7-8 carts, enough for ~1/3 of a LH flight's cart requirement for ~200 basic Y pax.
Replenishment of these two galleys would occur during meals: two "trains" of 3-4 carts would proceed to the rear lifts, blocking aisles only momentarily. Our 2 double-wide lifts lower the carts to belly in two movements (~2 minutes for MD, ~3 minutes for UD). Overall there should be little disruption to passengers.

My bad drawing doesn't specify the location of lavs except for the forward Y lavs and belly lavs - but I did estimate their impact in my pax counts. We'd need another ~6 lavs on the UD for PY/Y+, and 2 lavs on the MD for handicapped J pax who can't walk down to the belly.

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

This is just one possible iteration of the plane, of course. I intentionally imagined this layout to be versatile: It has extremely attractive J+ suites, ~130 overall flat bed suites, ~220-240 PY/Y+ seats, and ~400 Y- seats. It's dense enough to be "misused" on short megaroutes and premium enough to attract high-yield pax on longhaul.

For TPAC flights, basic Y would be ~$200 cheaper to operate than on today's A380.
PY would cost slightly less than Y on today's A380, Y+ even less.
With Zodiac Optima flatbed seats (new UA Polaris) as the "normal" J seats, your operating cost is about the same as PY.
The "Super J" suites cost about as much as a normal reverse-herringbone seat to operate.

So the marketing strategy with this layout would be to (1) attract high-yielding pax by offering a class step-up in comfort at equal price and/or (2) profitably compete on price everywhere else.
 
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Re: 2025ish A380-900NEO

Fri Apr 06, 2018 3:38 am

Eurofusion wrote:
Obviously a top hinged cargo door might not work for the trolley service area as a standard catering truck may not be able to get close enough? Would we need to make an onboard extendable gangway contraption to compensate?


We'd probably need custom catering equipment. I envision a ~9ft-wide platform extending from the catering truck and exchanging carts 8 at a time. This probably involves some marginal acquisition cost (one $50k truck for each $300mn plane?). But you'd save on the labor cost of wheeling individual trolleys through aisles one at a time.
 
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Re: 2025ish A380-900NEO

Fri Apr 06, 2018 2:24 pm

Eurofusion wrote:
Matt6461 wrote:
Slow to respond to a task previously mentioned in this thread. It involved building an approximate model of the proposed 900NEO/NWO I'm not an engineer so forgive the clumsy rendition but it's broadly based on the numbers - the wing profile however is a stab in the dark, forgive the pun. The nose has been redesigned in the vain of the A350 curved windscreens, so a cosmetic and efficiency double whammy.

The 3D model really is going to be the basis to demonstrate operational advantages of the re-designated belly space. An additional premium area, lavs and galley. However, most importantly a method to swap the trolley service whilst the main cabins are being cleaned and prepared. This will probably end up being an animation or click by stage animation. So anyway if there are any major show stopping comments to this profile let me know.

Image


@Eurofusion that's a gorgeous rendering, thanks!


I'll second that! Wow, that is PERFECT! Truly gorgeous. Thank you for taking the time to do that! I really hope somebody at Airbus sees that(so that you may get some praise around the office).
Unfortunately I may have to agree with Matt6461, that it's likely too gorgeous. But one can dream.
Thank you guys for contributing to this thread in such a positive way. It's been a pleasure following this thread. Matt6461 hit the nail on the head as to my reasoning of raising the cockpit slightly, earlier in the thread. Some of the technical stuff you guys are throwing out there is way over my head for contribution, but I enjoy reading it. :)
 
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Re: 2025ish A380-900NEO

Tue Apr 10, 2018 12:16 pm

Slug71 wrote:
Eurofusion wrote:
Matt6461 wrote:
Slow to respond to a task previously mentioned in this thread. It involved building an approximate model of the proposed 900NEO/NWO I'm not an engineer so forgive the clumsy rendition but it's broadly based on the numbers - the wing profile however is a stab in the dark, forgive the pun. The nose has been redesigned in the vain of the A350 curved windscreens, so a cosmetic and efficiency double whammy.

The 3D model really is going to be the basis to demonstrate operational advantages of the re-designated belly space. An additional premium area, lavs and galley. However, most importantly a method to swap the trolley service whilst the main cabins are being cleaned and prepared. This will probably end up being an animation or click by stage animation. So anyway if there are any major show stopping comments to this profile let me know.

Image


@Eurofusion that's a gorgeous rendering, thanks!


I'll second that! Wow, that is PERFECT! Truly gorgeous. Thank you for taking the time to do that! I really hope somebody at Airbus sees that(so that you may get some praise around the office).
Unfortunately I may have to agree with Matt6461, that it's likely too gorgeous. But one can dream.
Thank you guys for contributing to this thread in such a positive way. It's been a pleasure following this thread. Matt6461 hit the nail on the head as to my reasoning of raising the cockpit slightly, earlier in the thread. Some of the technical stuff you guys are throwing out there is way over my head for contribution, but I enjoy reading it. :)


I agree, its very pretty looking! probably easier to model a shape like that on CAD than the actual style A380 nose but it would probably have some pilot sighting issues which would mean that the windows would have to be massive if the shape was to remain like that.

Fred
Image
 
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Re: 2025ish A380-900NEO

Wed Apr 25, 2018 8:49 pm

So taking a bit of time on this to render the updated interior setup. Stealing time here and there. Sadly still on the first class suite area, anyway a teaser image Image. I will get through this hopefull before 2025! @Matt6461
 
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Re: 2025ish A380-900NEO

Thu Apr 26, 2018 11:23 pm

@Eurofusion I'll take what I can get, looks great so far.

There are an infinite number of possible layouts for a -900NEO, some of which might include F class. I didn't include F in my sketch above because I figured J+ would make it redundant. But I could also see an F+ product wherein the space-efficiency of the -900NEO allows F seats 2ab at ~80in pitch. That gets you basically a private cabin on the order of EY's Residence for each F pax.

For a layout with ~400 basic-Y seats, I'd still want to put Y at the front of the plane to enable faster turnaround. Behind MD D2 is ~40% of cabin area; you can put all your F+/J+/J in that space ("only" ~100 pax). Then behind UD D2 would go PY/Y+.

OTOH, given that our trip cost is ~10% lower than A388, which already pretty efficient, airlines could put only ~500 seats in a -900NEO, all of them premium-spaced, and sell each at 0% premium for extra space, while still being profitable. In that case TRT isn't such a big issue. I just think the optimal economic solution is a mix of super-cheap, dense Y seats and more spacious premium seats.
 
parapente
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Re: 2025ish A380-900NEO

Fri Apr 27, 2018 8:26 am

The work being done here is brilliant.But rant we putting lipstick on a pig?And no I am not trying to be rude to Airbus.
This 'people will 'have' to buy/fly such aircaft due to airport congestion' has been shown to be total codswallop.Sheer smoke and mirrors.
Is there really any need for a -900 however improved it may be? Hell the 800 is too big for all but a very few.First class is a dying breed so the space available is already enormous.Hell if they put in the new wider 777x economy seats (at 17.5" ) you can get X11 in Y Lowe floor easily.

Whilst not nearly as elegant as the above proposal Airbus have already shown us their 'next gen' 380 wing. It's gonna get a second wing twist and blended winglets ( and stay in 80 mtr box).

The only chance ( now -since they have clearly passed on the possible Trent ten option) would be 'the advance/ultra'.That depends entirely if RR choose to take a chance and build such an (replacement)engine for the 797 and A350 families.We know the test core is roughly in this thrust area as is the gearbox and carbon fan test work.So not impossible - but right now unlikely I fear.
If RR got a place on the 797 development project you could rule it out for sure in the near term as their hands would be full (and the bank empty).
 
BobbyPSP
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Re: 2025ish A380-900NEO

Fri Apr 27, 2018 4:25 pm

Eurofusion wrote:
Slow to respond to a task previously mentioned in this thread. It involved building an approximate model of the proposed 900NEO/NWO I'm not an engineer so forgive the clumsy rendition but it's broadly based on the numbers - the wing profile however is a stab in the dark, forgive the pun. The nose has been redesigned in the vain of the A350 curved windscreens, so a cosmetic and efficiency double whammy.

The 3D model really is going to be the basis to demonstrate operational advantages of the re-designated belly space. An additional premium area, lavs and galley. However, most importantly a method to swap the trolley service whilst the main cabins are being cleaned and prepared. This will probably end up being an animation or click by stage animation. So anyway if there are any major show stopping comments to this profile let me know.

Image


Lower deck galleys on L-1011, Dc10 and 747 were service via lower deck: did not hamper passengers
 
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Slug71
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Re: 2025ish A380-900NEO

Mon Jul 02, 2018 3:41 am

Its probably a couple years early at best, but it sure would be nice to hear something big at Farnborough.
 
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Matt6461
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Re: 2025ish A380-900NEO

Wed Jul 04, 2018 3:43 am

Slug71 wrote:
Its probably a couple years early at best, but it sure would be nice to hear something big at Farnborough.


No chance of something big. I'd love to hear just the barest discussion of a future path for the A380 beyond "someday we'll do a NEO." Surely there are plans somewhere within Airbus for future options. Let us in on something!

BobbyPSP wrote:
Lower deck galleys on L-1011, Dc10 and 747 were service via lower deck: did not hamper passengers


Just saw this... Does anyone have any pics of how this worked? Was there a separate galley servicing door or did galley servicing occur through the cargo compartment?
If the latter, the TRT impact wouldn't be much because cargo servicing is often the critical path or near-to-it for TRT.
 
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Slug71
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Re: 2025ish A380-900NEO

Wed Jul 04, 2018 5:07 am

Matt6461 wrote:
Slug71 wrote:
Its probably a couple years early at best, but it sure would be nice to hear something big at Farnborough.


No chance of something big. I'd love to hear just the barest discussion of a future path for the A380 beyond "someday we'll do a NEO." Surely there are plans somewhere within Airbus for future options. Let us in on something!


Oh a roadmap would be big enough for me. That'd be great.
 
Leitwolf22
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Re: 2025ish A380-900NEO

Thu Jul 05, 2018 5:24 pm

I think it is all about the center fuel tank, or the lack of it. Usually the center fuel tank would hold a decent percentage of the total fuel capacity and in its absence, the wings designers had a massive restriction to consider. It is no big secret, that the wings of the A380 are relatively inefficient and a cause otherwise unnecessary drag.

The lower deck must have been a major issue in designing the A380. There are a couple of factors restricting the space available.
1. Due to the double deck design, the main deck was moved a bit downward, reducing the space on the lower deck.
2. Because of the massive cross section, the tail section starts to taper relatively early, effectively reducing the length of the lower deck.
3. The undercarriage is massive and thus consumes a lot of space on the lower deck.
4. Other than on some aircraft, crew accomodations were moved to the lower deck, as there is no space above the upper deck.
5. Due to the large capacity there will be a lot of freight, or luggage respectively, to be concentrated in the already tight situation on the lower deck.

All this meant, that the lower deck was running out of space and so the center fuel tank was simply removed. Even though it may seem statically beneficial to move fuel into the wings, it certainly will make them "fater", heavier, and will cause more drag. Indeed the wings on the A380 look quite clumsy, compared to the lean and stream-lined designs on the A350, B787 or 747-8.

With a MTOW of 570t and ~525 pax the A380 is very heavy compared to modern wide bodys. But it should be obvious where the problem does NOT originate. Empty weight is about 275t. Wings account for 33tx2, engines have 6.5tx4, which leaves us with 183t. Next we have a massive empennage, maybe weighting up to 30t, and an undercarriage most certainly being close to 30t.

So we have a massive but extremely leight weight hull (including installments), but from that point on, something goes awefully wrong.

What if there was a center fuel tank? First of all the wings would become lighter and would procude less drag. The savings in weight would, as always, allow for weight savings in other places, most notably fuel of course. Less drag would save fuel too, but also it would stabilize the aircraft, reducing the requirements for the empennage, allowing for additional weight saving there, where again all the multiplicators would apply.

One could possibly save like 10t on the wings, another 5t on the empennage and possibly another 30t on fuel, both due to less weight and less drag. That would recude MTOW from 570t to 525t. That again would allow for smaller engines (next to more efficient ones with NEO version), and possibly a redesigned and lighter undercarriage.

However, as a matter of fact, there is no space for such a center fuel tank. That is unless you stretch the aircraft by 7-8m. That should give enough extra space to accomodate an 80.000l center fuel tank. Then, all of a sudden, you could build a very lean machine around the same old hull. Despite the additional payload and about 650 pax, you could yield a MTOW < 550t. And that is next to all other thinkable tweeks like improved engines, optimized use of cabin space, or the extensive use of composite materials.
 
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Matt6461
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Re: 2025ish A380-900NEO

Thu Jul 05, 2018 7:30 pm

Leitwolf22 wrote:
I think it is all about the center fuel tank


I see this is first post... Welcome.
I appreciate the thoughts but it's simply not true that A380's wing size is dictate by fuel volume storage requirements (i.e. a lack of center tank). A380 has more than enough fuel storage capacity already (i.e. it's weight-limited instead of volume-limited) and it would be easy to activate storage in the center wing box if needed.
Rather, A380's wing is sized for the -900 stretch, which with 2000 engine tech and absent big winglets would have implied MTOW of ~660t. With such a huge MTOW, you need a huge wing to get airborne.
Airbus Executive Tom Williams has specifically stated that the wing is sized for the -900.
 
Leitwolf22
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Re: 2025ish A380-900NEO

Fri Jul 06, 2018 3:26 am

Hi Matt

Sure I could be wrong, and I do not mind in case someone proves me wrong. However I do not see how a -900 would ever have resulted in 660t?! With wings, undercarriage, essentially everything already in place to support a stretch, what you get is like +10t for the longer hull, and another 10t for additional payload. Add some fuel to it, and you get quite precisely to a maximum of 600t. Or, sticking to the initial design MTOW of the -800 (560t), to about 590t, which is quoted at wikipedia for instance.

So the fact remains, that the A380 has an overproportionate wing. It has 148% the size of the 747-8, but the aircraft weights just 128%. I followed this issue quite a while and do not remember where I read it, though it was a respectable source, where it was stated that the wing is indeed inefficient due to the amount of fuel it must carry. You can say what you want about the 747-8, which features a super old hull. But its wings a very up to date. Btw.. I'd love to learn what their weight is.

Apart from that, if an aircraft like the A380 is underperforming the competition by such a significant margin, I think it is reasonable to ask what is different with this design. And the answer is simple and straight forward.

I do acknowledge there may be some space left in the center wing box, which goes unused. I would need to speculate why it has not been used. I could imagine that given the tight freight space they would reserve this as an option. However there is no way to put like 30% of the required fuel there. So yes, I'll stick to my point.
 
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Matt6461
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Re: 2025ish A380-900NEO

Fri Jul 06, 2018 6:32 am

@Leitwolf22 Here's the quote from Tom Williams, who designed the A380's wings:

Airbus executive vice president Tom Williams says that expanding the already huge A380-800 to even larger variants was the plan from the start.

“I lead the team that designed the wings of the A380, and (when she first saw the models) even my good lady wife was quick to point out that the wings are very big in comparison to the fuselage” Williams told Australian Business Traveller in 2011.

“The wings are in fact designed for a much larger airplane, so we have the capability of going to a bigger fuselage – we can stretch the fuselage very easily.”


https://www.ausbt.com.au/airbus-confirm ... 80-stretch

Also this quote from the A380's head engineer:
Airbus has built plenty of growth
potential into the A380 – “We have
not designed an aircraft with an
845m2
wing for nothing,” says the
programme’s senior vice-president
engineering, Robert Lafontan.


[Narrator: They had, in fact, designed the enormous wing for nothing]

https://www.flightglobal.com/assets/get ... temid=9139 (page 6)

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

You're vastly understating the weight implications of a -900. Stretch means not only a longer tube (10t is about right for that); it also means ~1,200ft2 more floor beams, more pax systems and furnishings. That's another 10t right there.

Then the wing has to be strengthened for the greater bending moment of the heavier heavier fuselage+payload/systems/furnishings/beams.
Your bigger fuselage creates more drag, which means your L/D goes down, which means you have to lift more fuel.
...which means additional MLG weight, perhaps even a whole additional MLG truck (there's room for such a truck in the MLG layout though there's been dispute as to whether the -900 envisioned such an addition).
You should be up by ~25t OEW, ~10t payload (100pax@225lbs), and lose ~4% L/D. Add ~70% to your (OEW+payload) delta to get MTOW delta and you're squarely at 640t.

At 640t, your wingloading is about the same as a 777-300ER. Whether the actual MTOW is a few tonnes less or more, your wing is no longer oversized.

Leitwolf22 wrote:
You can say what you want about the 747-8, which features a super old hull. But its wings a very up to date.


No. The 747-8's wing is merely relofted and extended - in its most important respects it is still a 1960's wing. You can tell this is true simply from its aspect ratio and sweep angle. Boeing proposed a real rewing of the 747 during the 1990's but didn't have enough customer interest to launch the project. The program that became 747-8 was explicitly chosen because it was (supposed to be) cheaper than a rewing.

Leitwolf22 wrote:
I do acknowledge there may be some space left in the center wing box, which goes unused. I would need to speculate why it has not been used. I could imagine that given the tight freight space they would reserve this as an option.


You seem to be under the impression that cargo compartments occupy space that otherwise would be used for fuel tankage? Please look into the definition of "center wing box tank" versus auxiliary tanks.
 
Leitwolf22
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Re: 2025ish A380-900NEO

Sat Jul 07, 2018 11:40 pm

Sorry, you are right on the 747-8s wing. It has been only overhauled rather than completely redesigned (although Boeing claims that in some occasions).

On the other side I can still not follow your logic on the MTOW of a -900. You say that the wing has been designed for a potential stretch version, which would be much heavier than I (and everyone else) think, because "Then the wing has to be strengthened for the greater bending moment", which again was due to a much larger weight, because the wing was not designed for a stretch!?

You are going in circles!

No, you will not need a reinforced wing for a stretch, except for some reinforcements due to some unexpected "cracks" (we know that story). Those quoted statements do not claim anything else, they are more like an "excuse" as to why the wing is too large. But since we already know that line of argument is pointless (as the -900 would hardly weight more!), and +/-5% MTOW do not require a different wing, it gets obvious they try to talk away something significant.

That significant thing is just what I explained. They completely screwed up by skipping the center fuel tank. For that reason the wings are not just oversized, but also too fat, causing a lot of drag, and having overweight.

PS. If you still happen to believe a simple stretch of ~10% would increase MTOW by a 15.7% (=1 - 660 / 570), then just compare this to real life examples with other aircraft.
 
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Matt6461
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Re: 2025ish A380-900NEO

Sun Jul 08, 2018 5:27 am

@Leitwolf22

You appear not to know the difference between wing size and wing strength - or even that these distinct concepts exist. A wing sized for a stretch requires less strength when fitted to a smaller fuselage; it has to be reinforced when fitted to a larger fuselage. This is a technically easy thing to do but has serious weight implications. Thus my mention of "bending moments." If you don't know what that term refers to, I advise you to research it before expending further time and effort in this thread.

You're brand new here so please take some advice: Try to realize that you'll often not know what you're talking about; don't worry about that; just try to learn.

When you say "X" and someone provides a quote from a plane's designers saying "not X," consider whether you're missing something and try to ask questions rather digging into your original position.
 
Leitwolf22
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Re: 2025ish A380-900NEO

Sun Jul 08, 2018 8:21 pm

I guess this table, though not perfectly precise, proves the case very well. We only need to consider the amount of fuel in the wing in relation to the size of the wing, as represented by wing area. Of course not under all the wing area you can store fuel, but yet it should be understandable, that a certain size of a wing can only store a certain amount of fuel.

Generally we see that Airbus puts relatively more fuel into the wing than Boeing. They were especially ambitious with the A340 500/600, which resulted in a wing with very high "thickness to chord" ratio. Of course the A340s 5&6 were no good performers accordingly.

The aircraft that tops it all however is the A380. Its wings have to hold a volume of about 360l/m2, far exceeding industry standards. One could argue that should be fine, as the wing is so large. I will strongly contradict on that, but the point something else. They could not have build a significantly smaller wing to accomodate that same amount of fuel. With a hypothetical 700m2 wing area, the wing would need to hold 436l/m2, which simply would not work.

So this gives us the definite answer to the question why the wing of the A380 is that oversized. Due to the lack of a center fuel tank, they simply had to be made that large to accomodate all the fuel.

    Type / fuel in wing / wing area / fuel/m2

    A380 / 305000 / 846 / 360.5
    (Option?) / 305000 / 700 / 435.7

    B777 / 120000 / 437 / 274.6
    B747-8 / 125000 / 554 / 225.6
    B787-9 / 84000 / 377 / 222.8
    B767-3 / 60000 / 283 / 212.0

    A330 / 93000 / 362 / 256.9
    A340-500 / 131662 / 437 / 301.3
    A350-9 / 100000 / 354 / 282.5
 
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Matt6461
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Re: 2025ish A380-900NEO

Mon Jul 09, 2018 1:26 am

Leitwolf22 wrote:
We only need to consider the amount of fuel in the wing in relation to the size of the wing, as represented by wing area


That you're measuring tankage by area instead of volume tells all one needs to know about the quality of this analysis. I haven't read beyond that sentence.

I hope someday you'll be in a position to recognize what complete nonsense you've written in this thread. Until then, I won't devote more effort to engaging with you. You've diminished enough an otherwise good thread.
 
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seahawk
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Re: 2025ish A380-900NEO

Mon Jul 09, 2018 9:41 am

The big unanswered question in all those debates would be the reason for the missing interest of airlines. It could be that the plane´s economics are the main reason, but maybe they are not the only reasons.
When you do a A380NG (it needs much more than just new engines), you need to be 100% certain that the modifications give you better market penetration and a sustainable product. And that is where I still have doubts, because I have heard to many rumours about things like seasonal demand, high trip costs, yield management, frequency over capacity, reshaping traffic flow to favour zero or one stop connections and so on.
And imho there are facts to support at least some of those rumours, for example the strong preference of the passenger for zero or one stop connections over 2 stops and more. We see this with more secondary airports getting direct connections to new markets but also by the quite interesting fact that the biggest A380 operator is able to offer the most one stop connections with it.

Attributing the missing success of the A380 solely to the economics of the plane might be aiming a bit short.
 
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Re: 2025ish A380-900NEO

Mon Jul 09, 2018 9:53 am

Indeed measuring tankage using wing area is very wierd.

Regarding maximum takeoff weight, a simple stretch doesnt have to increase in weight.

The A380 can fly some of the worlds longest routes. A simple 787-10 style stretch exchanging fuel for payload could work. 90+% of Emirates traffic is inside 6000nm so it shouldn't be an issue. The 777X is also a stretch which keeps the same maximum takeoff weight and its new engines allows it to fly just as far.

Adding extra structural weight to increase the A380's maximum takeoff weight above 600T will just reduce efficiency on the shorter routes.
 
Leitwolf22
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Re: 2025ish A380-900NEO

Mon Jul 09, 2018 6:03 pm

I need to add a little correction. The 747-8 will rather have about 139.000l in the wings, just like the 747-4. We could also add the MD 11..

    B747-8 / 139000 / 554 / 251
    B747-4 / 139000 / 541 / 257
    MD-11 / 62665 / 339 / 185

As I already told, overloading the wing with fuel is due to the lack of space on the lower deck. There is another nice piece of evidence for that problem if we look at cargo capacity. We see very well how the A380 is the most restricted aircraft in terms of cargo, despite being the only one not to have a center fuel tank. I do not know how smart one needs to be to understand the obvious, but certainly not very much (that goes to the intellectual limbo dancers)

    type / cargo m3 / pax / cargo/pax
    A380-8 184 550 0.335
    B747-4 160 416 0.385
    B747-8 180 467 0.385
    A350-9 172 325 0.529
    A340-6 202 380 0.532
    A330-3 158 295 0.536
    B767-3 114 210 0.543
    B777-3 202 365 0.553
    B767-4 139 243 0.572
    A350-10 210 366 0.574
    B777-9 230 400 0.575
    B787-10 191 330 0.579
    B787-9 172 290 0.593

Is that the only problem of the A380? Well, more or less, but not the only perspective. A new aircraft most of all is a business case. As such it should not only be comparing favourable with the competition in certain scenarios (or in a lot of which), it should also force its way into the market. The new design should be an asset to every airline opporating it, putting other airlines under pressure if they do not opporate that aircraft.
Size itself (in the shape of the A380) may be nice to show off, as well as the amenities going along with it, but it is not pressuring anyone. The downside is the challenge of filling an aircraft of that size. So there hardly is any business case with the A380.
What the A380 should be is an aircraft offering economies of scale with much lower opporating costs per passenger if you can fill the aircraft. Then it would still be a challenge, but one that possibly pays off in the end. With a mix of lower prices, more comfort and higher profits, those airlines who dare and succeed will trash the competition. The competition is then pressured to try the same and aquire additional A380s for themselves, and so on..

The A380 however fails on that challenge. Even if you fill it up completely, there is no way to economically outrun the competition. To do so, the A380 would need to be much more fuel efficient than it is. It could and would be so, if there was not that stupid design flaw regarding the center fuel tank. The only way to get the A380 airborne (as a business case) was and is to stretch it to 80m and then adding a center fuel tank, while trimming the wings.
 
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Matt6461
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Re: 2025ish A380-900NEO

Tue Jul 10, 2018 4:12 am

RJMAZ wrote:
Regarding maximum takeoff weight, a simple stretch doesnt have to increase in weight.


I don't see a range-restricted A380 working.
Its heartland mission is to move large numbers over long distances; its economic rationale is less compelling on short haul.*

*my proposed A380NEO would be excellent on short haul when deployed to increase utilization.
 
RJMAZ
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Re: 2025ish A380-900NEO

Tue Jul 10, 2018 10:24 am

Matt6461 wrote:
RJMAZ wrote:
Regarding maximum takeoff weight, a simple stretch doesnt have to increase in weight.


I don't see a range-restricted A380 working.
Its heartland mission is to move large numbers over long distances; its economic rationale is less compelling on short haul.*

*my proposed A380NEO would be excellent on short haul when deployed to increase utilization.

I dont see it being range restricted.

To estimate the performance of a straight stretch we could assume the A380NEO engines will burn 10% less fuel with the same thrust. An A380 currently flying ultra long haul will carry nearly 250t of fuel. That means the NEO would need 25T less fuel to travel the same distance. I am fairly certain a straight simple stretch to 80m would add approximately 25T in weight or even less.

If we assume the fuselage tube represents a third of the 276T empty weight. The tube then weighs approximately 92T. A 10% stretch to 80m would then add only 9T. Double that weight to 18T to account for a bit of strengthening and its still less than the fuel saved by the engines.

Once you add the extra surface drag from the stretch it will probably balance out. The NEO could then carry the same payload the same distance as the current model while burning less fuel and maintaining the original maximum takeoff weight.

Increasing payload by 10% to make use of the extra cabin area would result in the range reducing by less than 5%.

There is only two routes that use the maximum range of the A380. Auckland to Dubai and Sydney to Dallas. Both airlines will have 777X in their fleets to do those routes. The simple stretch A380-900NEO could then perform all of the other existing A380 routes.

Even the slightest increase in the maximum takeoff weight would start to eliminate the range reduction of the simple stretch A380-900NEO.

If the engines only had a 5% efficiency improvement then obviously range would suffer unless the maximum takeoff weight was increased to around 600T.
 
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Re: 2025ish A380-900NEO

Tue Jul 10, 2018 11:49 am

Should not need much strengthening as the 800 is the shrink and the 900 was always planed.
 
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Re: 2025ish A380-900NEO

Tue Jul 10, 2018 8:06 pm

@RJMAZ you're mixing up my projections for a -900NEO and for the "original" -900. Only the latter would have needed increased MTOW.
My -900NEO has ~525t MTOW. That's assuming you can add huge wingtips to increase effective span abou 300ft, which underlies a virtuous cycle of weight reduction (though on net -900NEO would still be a bit heavier than -800).
 
Leitwolf22
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Re: 2025ish A380-900NEO

Sun Jul 15, 2018 6:26 am

I wanted to know what the volume of an A380 wings is. I could not find any info on that, but I could use this contour drawing to get a reasonable estimate.

https://de.wikipedia.org/wiki/Airbus_A3 ... 00v1.0.png

Measuring a number of waypoints allowed me to calculate a volume 310m3 if the wing had a rectangular profile (which of course it has not). That is based on the hight, depth and thickness on about 10 points (or cross sections if you will) of the wing.

Given a normally shaped wing, the overall volume may be around 60% of that, or roughly 210m3. Due to the concave shape of the wing profile (as seen from the front) it will be slightly less. Also the interior volume will obviously be less than the exterior volume. And even then, not all of that interior volume will be usable as a fuel tank.

The (single) wing of the A380 provides a volume of 152.4m3 for fuel. That is 72.5% of the thus derived exterior volume of the wing. I will assume that is pretty much the maximum of fuel you can put into a wing.

That result is pretty much in line with all the rational considerations in this thread so far (which are all mine btw. ;) ). The size of the wing has been determined by the demand to store fuel inside them. Less wing, less fuel, less range. Which of course brings us all back to the pivotal center fuel tank.

Another interesting detail is, that there is this issue with a tiny bit of space left in the wheel box to accomodate some fuel, which has not been used. One could argue, this was not used as the wing could carry it all.

Airbus however was not just planing with an -800 and a -900 version, they also had a -700 offering. The 700 was absurd, as it would have had the capacities of a 747-8, with about 100t in additional MTOW. Yet engineers had to take it into account. With the 800 already being horrible in terms of cargo, all space possibly left in the belly would need to be activated with the 700.

For that reason it was a rationale decision to put all fuel in the wings and skip the center fuel tank completely. Ultimately that leads to an amazing, but fully logical conclusion. The A380s wing is not oversized because of providing for the -900, but rather for the 700! Btw. even for the 900 the wing would oversized, as explained above.

Also I do see how certain people have a problem with this logical and undeniable reasoning. There are people who have very little understanding of the subject and actually think the solution of the problem which is lack of space in the belly and the thus oversized wing, could be solved by putting more stuff into the belly and shrinking the wing.
 
Leitwolf22
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Re: 2025ish A380-900NEO

Sun Jul 15, 2018 6:30 am

Correction: "That is based on the hight, depth and thickness on about 10 points (or cross sections if you will) of the wing."

I meant depth and thickness, while allowing for the distance between these waypoints.
 
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Re: 2025ish A380-900NEO

Sun Jul 15, 2018 9:10 am

Leitwolf22 wrote:
So this gives us the definite answer to the question why the wing of the A380 is that oversized. Due to the lack of a center fuel tank, they simply had to be made that large to accomodate all the fuel.

poppy cock.

The center tank is there ( ~50m³ ). unused. ( no need, would need MTOW increase and would move range through the roof.)

1D linear scaling of 3D objects ( and thus tank volume ) is ^3 while area is only ^2.

design constraints favor a proportionally shorter, stubbier wing when you scale upwards.
( plot a range of types in logscale MTOW over wingspan and you see the effect.)
Murphy is an optimist
 
Leitwolf22
Posts: 12
Joined: Thu Jul 05, 2018 1:36 am

Re: 2025ish A380-900NEO

Mon Jul 16, 2018 1:36 pm

WIederling wrote:
The center tank is there ( ~50m³ ). unused


I do not think so. There is no fuel tank, there is only unused space (unused for the reasons named). And that space, according to what I have read, is about 35m3 only. So it would be great if you had any source supporting your claim.
 
WIederling
Posts: 6498
Joined: Sun Sep 13, 2015 2:15 pm

Re: 2025ish A380-900NEO

Mon Jul 16, 2018 4:50 pm

Leitwolf22 wrote:
WIederling wrote:
The center tank is there ( ~50m³ ). unused


I do not think so. There is no fuel tank, there is only unused space (unused for the reasons named). And that space, according to what I have read, is about 35m3 only. So it would be great if you had any source supporting your claim.


an eclosure designed to be used as tankage is nothing but unused space, isn't it?

You have to look for A380-900 preliminary specs:
https://de.wikipedia.org/w/index.php?ti ... 0#A380-900
( try to find the prelim ACAPS from back then. I haven't stored that )
A380-800 has 320kl, the A380-900 would have gotten 370kl that is a markup of 50kl or ~35t fuel.

3 clicks beyond google would have refuted your argument before you brought it up, even.
Murphy is an optimist
 
Leitwolf22
Posts: 12
Joined: Thu Jul 05, 2018 1:36 am

Re: 2025ish A380-900NEO

Mon Jul 16, 2018 9:49 pm

WIederling wrote:
Leitwolf22 wrote:
WIederling wrote:
The center tank is there ( ~50m³ ). unused


I do not think so. There is no fuel tank, there is only unused space (unused for the reasons named). And that space, according to what I have read, is about 35m3 only. So it would be great if you had any source supporting your claim.


an eclosure designed to be used as tankage is nothing but unused space, isn't it?

You have to look for A380-900 preliminary specs:
https://de.wikipedia.org/w/index.php?ti ... 0#A380-900
( try to find the prelim ACAPS from back then. I haven't stored that )
A380-800 has 320kl, the A380-900 would have gotten 370kl that is a markup of 50kl or ~35t fuel.

3 clicks beyond google would have refuted your argument before you brought it up, even.


Ok .. so you have absolutely nothing to support your claim?!

The german wikipedia states some inconsistent phantasy figures on the A380-900, as there are no specs available (and have never been!). Again it should not take a genius to understand, that a 590t 900 (that figure may be correct), with 35t of additional fuel (!?), will not result in in 1.000km less range! Also there is absolutely no statement on where that additional fuel would be stored. Then 50.000l =! 35t, but rather 39.25t.

Once I am at it, let me go on with your previous post..

WIederling wrote:
The center tank is there ( ~50m³ ). unused. ( no need, would need MTOW increase and would move range through the roof.)


No, wrong logic! Almost all the fuel is in the wing BECAUSE they skipped the center fuel tank. So the wings are oversized because of the missing center fuel tank, while the center fuel tank is not missing because of the oversized wings..

WIederling wrote:
1D linear scaling of 3D objects ( and thus tank volume ) is ^3 while area is only ^2.


..talking off subject to yourself..?

WIederling wrote:
design constraints favor a proportionally shorter, stubbier wing when you scale upwards


I have explained in very detail why the wing of the A380 is like it is. You should know and understand by now.
 
WIederling
Posts: 6498
Joined: Sun Sep 13, 2015 2:15 pm

Re: 2025ish A380-900NEO

Tue Jul 17, 2018 7:24 am

Leitwolf22 wrote:
I have explained in very detail why the wing of the A380 is like it is. You should know and understand by now.


I find it difficult to understand your misconceptions.
Murphy is an optimist

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