Kikko19 wrote:

ElroyJetson wrote:

RJMAZ wrote:

It is the same.

The A350-900 MTOW is 10% heavier than the 787-9 (280T vs 254T). The A350-900 has 7.5% more span (64.75m 60.12m)

The 777-8 MTOW is 11% heavier than the A358-1000 (351T vs 316T). The 777-8 has 9.5% more span (71.8m vs 64.75m)

Now this clearly shows you are wrong. The 777-8 wing is clearly big enough to carry the extra mass.

Any argument saying the A350-900 is better than the 787-9 can be also used to explain why the 777-8 is better than the A350-1000.

Any argument saying the 787-9 is better than the A350-900 can be used to explain why the A350-1000 is better than the 777-8.

Yet the Airbus guys will say the A350 is better in all situations. They will say the A350-900 lifts more payload further than the 787 and that trip fuel burn is not important. Yet when they compare the A350 to the 777X they suddenly say trip burn is the most important and that lifting more payload is not important.

The A350-900 and 787-9 both sell well and they both have pros and cons. Likewise the 777-8 and the A350-1000 they both have pros and cons. People are making it out like the 777-8 has no advantages at all over the A350-1000.

I think you nailed it. A great summary of those that employ constantly shifting arguments that always, always end up favoring only one side.

Both the 778 and A 351 are very close in terms of fuel burn and payload. It will be interesting to see which plane Qantas picks. I see this as almost identical to the A359 and 789 competition. One frame is lighter, has better fuel burn, and is less costly ( 789). One is heavier, burns more fuel, but can carry more payload and is optimized better for ULH missions (A 359).

Hello 778 vs A 351. The exact same dynamic. May the best plane win.

doesn't the fact that the 77x is an old frame with new engine instead make it like the a339 vs the 789?

I don’t think it’s comparable. The 779 does sell and has no direct competition being slightly larger than the A35K. The 778 is an ULH “beast” and designed for that purpose.

Kikko19 wrote:

ElroyJetson wrote:

RJMAZ wrote:

It is the same.

The A350-900 MTOW is 10% heavier than the 787-9 (280T vs 254T). The A350-900 has 7.5% more span (64.75m 60.12m)

The 777-8 MTOW is 11% heavier than the A358-1000 (351T vs 316T). The 777-8 has 9.5% more span (71.8m vs 64.75m)

Now this clearly shows you are wrong. The 777-8 wing is clearly big enough to carry the extra mass.

Any argument saying the A350-900 is better than the 787-9 can be also used to explain why the 777-8 is better than the A350-1000.

Any argument saying the 787-9 is better than the A350-900 can be used to explain why the A350-1000 is better than the 777-8.

Yet the Airbus guys will say the A350 is better in all situations. They will say the A350-900 lifts more payload further than the 787 and that trip fuel burn is not important. Yet when they compare the A350 to the 777X they suddenly say trip burn is the most important and that lifting more payload is not important.

The A350-900 and 787-9 both sell well and they both have pros and cons. Likewise the 777-8 and the A350-1000 they both have pros and cons. People are making it out like the 777-8 has no advantages at all over the A350-1000.

I think you nailed it. A great summary of those that employ constantly shifting arguments that always, always end up favoring only one side.

Both the 778 and A 351 are very close in terms of fuel burn and payload. It will be interesting to see which plane Qantas picks. I see this as almost identical to the A359 and 789 competition. One frame is lighter, has better fuel burn, and is less costly ( 789). One is heavier, burns more fuel, but can carry more payload and is optimized better for ULH missions (A 359).

Hello 778 vs A 351. The exact same dynamic. May the best plane win.

doesn't the fact that the 77x is an old frame with new engine instead make it like the a339 vs the 789?

I wasn't aware the A339 had a new wing and carbon fiber technology like the 77X. If so you might have a valid argument.

It seems the 777-8X has a smaller cabin floor area than the A35K. It is a heavier airframe with less passenger capacity.
The 787-9 has a smaller cabin floor area than the A359. It is a lighter airframe with less passenger capacity.

Isn't that a significant difference in dynamics for a passenger aircraft?

If Airbus can make an A35K lift the same payload as a 778X over the same ULR distance, it means Qantas can hypothetically block economy seats off to equal the full capacity of the 778X without a cost disadvantage. They can fill the aircraft up on shorter routes...and perhaps even replace the A380? The theoretical A35K "Sunrise" seems far more versatile here.

Cabin floor areas: viewtopic.php?t=769733#p11106553

RJMAZ wrote:

It is the same.

The A350-900 MTOW is 10% heavier than the 787-9 (280T vs 254T). The A350-900 has 7.5% more span (64.75m 60.12m)

The 777-8 MTOW is 11% heavier than the A358-1000 (351T vs 316T). The 777-8 has 9.5% more span (71.8m vs 64.75m)

Now this clearly shows you are wrong. The 777-8 wing is clearly big enough to carry the extra mass.

Any argument saying the A350-900 is better than the 787-9 can be also used to explain why the 777-8 is better than the A350-1000.

Any argument saying the 787-9 is better than the A350-900 can be used to explain why the A350-1000 is better than the 777-8.

I don't agree that any argument saying the A350-900 is better than the 787-9 can be also used to explain why the 777-8 is better than the A350-1000, and vice versa. The world is more complicated than that. These are very different aircraft, aircraft of different size.

The A359 cabin is almost 10 % larger than the 789 cabin. In order words, the largest aircraft is slightly heavier, have a higher MTOW and a larger wingspan. The opposite is true for the A35K vs 778. The A35K cabin is almost 10 % longer than the 778 cabin, yet the largest aircraft has a lower OEW, has a lower MTOW and a shorter wingspan.

The comparisons between 789/A359 and 778/A35K are not analog at all.

RJMAZ wrote:

Now you say the lighter plane with the smaller wing is better. I'm sure I am not the only one that can detect a heavy bias.

you feel too counter biased ? ))))))))

RJMAZ wrote:

It is the same.

The A350-900 MTOW is 10% heavier than the 787-9 (280T vs 254T). The A350-900 has 7.5% more span (64.75m 60.12m)

The 777-8 MTOW is 11% heavier than the A358-1000 (351T vs 316T). The 777-8 has 9.5% more span (71.8m vs 64.75m)

Now this clearly shows you are wrong. The 777-8 wing is clearly big enough to carry the extra mass.

Any argument saying the A350-900 is better than the 787-9 can be also used to explain why the 777-8 is better than the A350-1000.

Any argument saying the 787-9 is better than the A350-900 can be used to explain why the A350-1000 is better than the 777-8.

Yet the Airbus guys will say the A350 is better in all situations. They will say the A350-900 lifts more payload further than the 787 and that trip fuel burn is not important. Yet when they compare the A350 to the 777X they suddenly say trip burn is the most important and that lifting more payload is not important.

The A350-900 and 787-9 both sell well and they both have pros and cons. Likewise the 777-8 and the A350-1000 they both have pros and cons. People are making it out like the 777-8 has no advantages at all over the A350-1000.

sigh, you made the same mistake again.

You are looking at the physical span, which is useless in air, actually air simply doesn't see the wing that way. Add the effect of each wingtip device and you will see what you have missed. Otherwise, poor Boeing and Airbus are wasting their time and capital investing in wingtip devices for nothing.

By using the 80% and 45% rule for raked and blended wingtips equivalent length:

Effective wingspan for 789: 58.8m (roughly )
Effective wingspan for A359 and A35K: 66.55m (roughly)
Effective wingspan for 778: 70.35m (roughly)

A359 has an effective wingspan that is 13.2% longer than 789's, and 778 has a wingspan that is 5.7% longer than A35K. Now with their respective MTOW, redo your calculations. You will how the two cases aren't the same.

In both cases, A359 and A35K had a lower span loading.

I am sceptical to the degree to which 'operational flexibility' is going to impact on the final decision.

At the end of the day, flying either a 250 seat A35K or 280 seat 778 in a 4 class configuration between Melbourne and Hong Kong is going to have lousy economics.

You are going to want to ULH aircraft pretty much exclusively flying ULH or LH routes. You will only use them of medium haul flights as a last resort.

scbriml wrote:

RJMAZ wrote:

Qantas operate 787's which share a type rating with the 777. Pilot training would then be cheaper with the 777X.

This is a pointless argument - QF also operates A330s and A380s, so pilot training costs will be a wash.

RJMAZ wrote:

Rolls Royce has fairly poor reliability as of late so I'd put my money on the GE engines being much cheaper to maintain.

Another non-argument - the Trent XWB has been very reliable and GE9X maintenance costs are so far unknown.

On acquisition cost the 787-9 competes more with the A330, than it does with the A350.

There a lot of factors in the economics battle with CASM being just one of them.

Using the Emirates first quarter results as a datam point, fuel represented 32% of total costs. Considering they are a long haul airline operating previous generation A380's and 777's a 10% fuel efficiency advantage will only ever result in a trip cost advantage of 2-3%.

On the flip side revenue opportunity is where an airline like QANTAS wanting to fly ultra long haul aircraft will make its money.

If QANTAS can increase their revenue opportunity by 20% by flying a heavier aircraft,
less efficient aircraft, a 3% trip cost disadvantage is really going to be moot. The extra revenues will more than outweigh the additional costs.

For me the equation for this battle will come down to which aircraft is the more versatile and represents the least amount of risk.

On this front I am backing the A350. On pure revenue and I suppose we can throw marketing opportunity the

Eyad89 wrote:

sigh, you made the same mistake again.

You are looking at the physical span, which is useless in air, actually air simply doesn't see the wing that way. Add the effect of each wingtip device and you will see what you have missed. Otherwise, poor Boeing and Airbus are wasting their time and capital investing in wingtip devices for nothing.

By using the 80% and 45% rule for raked and blended wingtips equivalent length:

Effective wingspan for 789: 58.8m (roughly )
Effective wingspan for A359 and A35K: 66.55m (roughly)
Effective wingspan for 778: 70.35m (roughly)

A359 has an effective wingspan that is 13.2% longer than 789's, and 778 has a wingspan that is 5.7% longer than A35K. Now with their respective MTOW, redo your calculations. You will how the two cases aren't the same.

In both cases, A359 and A35K had a lower span loading.

You did the calculations for the A350 and 777X a few posts up but may I ask you to break-down the calculation for the 787 effective span? Please.

I am learning a lot here. Thank you for this!

May you please also elabortae a little bit more on the span loading.

RJMAZ wrote:

The A350-900 MTOW is 10% heavier than the 787-9 (280T vs 254T). The A350-900 has 7.5% more span (64.75m 60.12m)

The 777-8 MTOW is 11% heavier than the A358-1000 (351T vs 316T). The 777-8 has 9.5% more span (71.8m vs 64.75m)

Now this clearly shows you are wrong. The 777-8 wing is clearly big enough to carry the extra mass.

Any argument saying the A350-900 is better than the 787-9 can be also used to explain why the 777-8 is better than the A350-1000.

In the long tech ops thread we analysed the 787-9 vs the A350-900. In that thread we looked at the same payload over the same distance, for the 40t payload the difference in landing weight was just 4.57%, the trip fuel burn difference on average was less than 1%. The A350-900 being optimised for long haul started to burn less fuel than the 787-9 above 6000 nm.

Looking at Fred’s spreadsheet above the landing weight of the 777-8 will be 207 tonnes, the landing weight of the A350-1000 181 tonnes (assuming 6 tonnes reserve each). That is a delta of 14.42% (207788/181589). Trip fuel is added on top of that.

What Fred has used is a model, not real data, you have to expect it will not be like that in real life. Fred’s model actually exceeds some aircraft limits which would be observed in real life.

We used real data in the tech ops thread to compare the 787-9 to A350-900. That is not being done with the model, anyone making absolute claims based off that just does not understand the limitations of such models.

Also someone else has already gone into some detail to explain effective span on this thread. No need for me to repeat that.

Pacific wrote:

It seems the 777-8X has a smaller cabin floor area than the A35K. It is a heavier airframe with less passenger capacity.
The 787-9 has a smaller cabin floor area than the A359. It is a lighter airframe with less passenger capacity.

I think that is history repeating itself again, the A340-600 would carry more payload with a heavier airframe, however had less cabin areas than the 77W.

Eyad89 wrote:

sigh, you made the same mistake again.

Don’t think it was a mistake at all.

moyangmm wrote:

I wonder if a MTOW-increased 787-10 can be considered for Project Sunrise. I think if Boeing managed to bump 787-10 to around 280t it could be able to do it much more efficiently than A350-1000.

On the same mission my numbers have it needing 127t of fuel but a takeoff weight of 301t and needing a runway length of about 50% greater than the others required and some special new tyres for going that fast to get up and pavement loading numbers that are very high although the specifics of how the ACN numbers are calculated still seem like you might have to be in the boys club to know it.

the 787-10 needs a new engine, a new wing and new gear to make it possible and this adds weight making the above number moot.

Fred

enzo011 wrote:

smartplane wrote:

Dropping the 778 might allow Boeing to offer a second wing / landing gear option for the 787, and perhaps an -11, moving into 778 territory.

Profitability per air frame for the 787 family is many magnitudes greater than the 777X is ever likely to reach.

There is a possibility that while profitability of the 787 increases, that would be tempered by having a one family aircraft at the high end of the capacity range. If Boeing sees a slowing of demand for the 779 then it could mean that everything just about stays where they are. They are more profitable with the 787 but less than projected with the 777X.

Subtopic, I think that would be the best longer term Boeing strategy for big twins. The 787-8, 787-9, 787-10 wing proved maxed out for the -10, limiting it's payload-range for typical flight to/from Asia. The segment where Airbus sold 900 A350's. If Boeing up-sizes the 787 wing (as they planned at launch..), they will have a fully competitive 350 seat-80000Nm platform again, benefiting from the 14 aircraft/month 787 supply chain and economies of scale.


https://www.airliners.net/forum/viewtopic.php?t=1393909

It's a key segment left open after the 777-300ER, which wasn't absorbed by the payload range restricted 787-10 and the heavy, expensive 777-8. Boeing also would tap into UltraFan availability at the end of next decade. I think customers preferences will push Boeing in this direction. IMO it's more a "when" than "if".

In the category, "Something everyone knows but no one wants to admit": the 787 backlog has been shrinking over the last 5 years. That motivates..

Keesje, do they kind of recycle water for those 80000Nm missions?

EChid wrote:

It's a big deal in the sense that, before that, the requirement for a higher number would have put the A35K squarely out of the running. So, the issue is not that the potential candidates were too big, but that one was too small. Now they are both feasible. It might also be a big deal to QF. They may have done it simply so that Airbus could compete, or they may have done it because they assessed the market (and their needs in the rest of the network) and figured out that that was as much as it could bear for a flight that long. Don't know.

I am open to correction that Qantas has had the requirement from the start for 300 passengers. Airbus proposed the A359 which would not be able to fulfill this requirement. Hence we are seeing the current talk of 778 vs A35K as solutions for the flight.

Also, as other has shown the A35K has a bigger cabin area than the 778 so if the A35K is too small then the 778 is also too small. Now the advantage the 778 has it will fit one extra seat per Y row than the A35K, so a longer cabin or bigger cabin area doesn't always mean a higher capacity in seats. At the same time if you have the same amount of seats in the A35K and 778 there will be more personal space for passengers in the Airbus. Will the airline care? Not likely, but if you are going to subject your passengers to a 20 hour flight I think it has to be a consideration.

enzo011 wrote:

I am open to correction that Qantas has had the requirement from the start for 300 passengers. Airbus proposed the A359 which would not be able to fulfill this requirement. Hence we are seeing the current talk of 778 vs A35K as solutions for the flight.

Also, as other has shown the A35K has a bigger cabin area than the 778 so if the A35K is too small then the 778 is also too small. Now the advantage the 778 has it will fit one extra seat per Y row than the A35K, so a longer cabin or bigger cabin area doesn't always mean a higher capacity in seats. At the same time if you have the same amount of seats in the A35K and 778 there will be more personal space for passengers in the Airbus. Will the airline care? Not likely, but if you are going to subject your passengers to a 20 hour flight I think it has to be a consideration.

QF back in November said it no longer required 300+ seats and does not expect a full aircraft. Obviously Joyce hasn’t been reading a.net, the requirements are for a full aircraft apparently.

“However, regardless of the jet chosen to make those marathon 18-20 hour treks, there’s no longer an expectation that it will carry the airline’s previously-stated goal of 300+ passengers across four classes.

“Our belief is [ultra-long-haul flights are] not going to be full passenger payload and freight, but there is sufficient capability to make it commercially viable,” Qantas CEO Alan Joyce has told The South China Morning Post.

Joyce has until now been bullish on expectations that the non-stop flights would have over 300 seats spread across first class, business class, premium economy and economy.”

From. https://www.ausbt.com.au/qantas-ceo-dia ... pectations

Makes sense. If they can fill F, J and W to/from London they won't be too concerned about having to block seats in Y.

And that's one thing that advantages the A350 imho. It's likely to get a new engine earlier, so QF could then get full use of the aircraft, and shift the original 350s to shorter routes.

qf789 wrote:

Qantas says both Airbus and Boeing meet the Project Sunrise challenge and it is expected that a RFP will completed by end of next year with first delivery in 2022.

Boeing is proposing a tweaked version of the 777-8 while Airbus is offering a tweaked version of the A359ULR in the form of the A350-1000ULR

QF CEO says the A350 is more adaptable to places such as HKG and LAX due to it being lighter however in the longer term the 777-9 would be a better replacement for the A380

https://www.airlineratings.com/news/boe ... don-dream/

https://www.reuters.com/article/us-qant ... SKCN1L80MC

Reviewing this, I have to favor Boeing. UA already runs a 789 LAX SYD I think. So the inclusion of the 779 as part of an overall offering provides a more complete solution for QF.

justloveplanes wrote:

Reviewing this, I have to favor Boeing. UA already runs a 789 LAX SYD I think. So the inclusion of the 779 as part of an overall offering provides a more complete solution for QF.

And QF runs 789s BNE-LAX, MEL-LAX, MEL-SFO and soon SYD-SFO

But that's means nothing for a 777 v 350 decision.

keesje wrote:

Subtopic, I think that would be the best longer term Boeing strategy for big twins. The 787-8, 787-9, 787-10 wing proved maxed out for the -10, limiting it's payload-range for typical flight to/from Asia. The segment where Airbus sold 900 A350's. If Boeing up-sizes the 787 wing

Thr 787NEO in 10 years time will mean the current wing will be fine. Each 787 model could then fly 500+nm further with the same payload or carry 20+% more payload over the same distance. The 787-10NEO could then fly most of the flights operated by the 787-9 today.

The 787-8ER with the 254T takeoff weight would have been able to do the project sunrise flight. I do expect this to appear after the 797 comes out. It will simplify production being a straight shribk if the 787-9. The empty weight will probably increase by around 4000kg.

moa999 wrote:

RJMAZ wrote:

Qantas operate 787's which share a type rating with the 777. Pilot training would then be cheaper with the 777X.

Also operate a lot more 330s (28 in all) which have common ratings with the 350.
https://www.airbus.com/newsroom/news/en ... ining.html

And they will likely be considering retiring the first 332s at the time Sunrise aircraft begin deliveries.

but the a330s are on their way out, to be replaced by 787s and probably the 797 if it launches.

ElroyJetson wrote:

zeke wrote:

RJMAZ wrote:

The A350-900 MTOW is 10% heavier than the 787-9 (280T vs 254T). The A350-900 has 7.5% more span (64.75m 60.12m)

The 777-8 MTOW is 11% heavier than the A358-1000 (351T vs 316T). The 777-8 has 9.5% more span (71.8m vs 64.75m)

Now this clearly shows you are wrong. The 777-8 wing is clearly big enough to carry the extra mass.

Any argument saying the A350-900 is better than the 787-9 can be also used to explain why the 777-8 is better than the A350-1000.

In the long tech ops thread we analysed the 787-9 vs the A350-900. In that thread we looked at the same payload over the same distance, for the 40t payload the difference in landing weight was just 4.57%, the trip fuel burn difference on average was less than 1%. The A350-900 being optimised for long haul started to burn less fuel than the 787-9 above 6000 nm.

Looking at Fred’s spreadsheet above the landing weight of the 777-8 will be 207 tonnes, the landing weight of the A350-1000 181 tonnes (assuming 6 tonnes reserve each). That is a delta of 14.42% (207788/181589). Trip fuel is added on top of that.

What Fred has used is a model, not real data, you have to expect it will not be like that in real life. Fred’s model actually exceeds some aircraft limits which would be observed in real life.

We used real data in the tech ops thread to compare the 787-9 to A350-900. That is not being done with the model, anyone making absolute claims based off that just does not understand the limitations of such models.

Also someone else has already gone into some detail to explain effective span on this thread. No need for me to repeat that.

Yes, you arbitrarily picked a payload weight favorable for the A359. The numbers look much different with a 30t or 35t payload.

I showed you the same bias comparing the 778 vs the A351. The 778 can carry 51t payload 1500nm farther.

Choosing conditions to make your argument doesn't make it correct.

From what I understand the payload selected was to match the stated desire from Qantas. No surprise there.

As ever though we on here, even the experts, have less data and poorer models for the frames being proposed than Qantas do. I do wonder why people get so het up about it.

musman9853 wrote:

but the a330s are on their way out, to be replaced by 787s and probably the 797 if it launches.

Delivered 2002-2012. Many will be with Qantas for at least another decade

moa999 wrote:

musman9853 wrote:

but the a330s are on their way out, to be replaced by 787s and probably the 797 if it launches.

Delivered 2002-2012. Many will be with Qantas for at least another decade

sure. but the older ones are pushing 2 decades, and qf has clearly started replacement planning. and given how much alan joyce seems to like the 797, is anyone actually doubting qf wouldnt buy them?

musman9853 wrote:

moa999 wrote:

musman9853 wrote:

but the a330s are on their way out, to be replaced by 787s and probably the 797 if it launches.

Delivered 2002-2012. Many will be with Qantas for at least another decade

sure. but the older ones are pushing 2 decades, and qf has clearly started replacement planning. and given how much alan joyce seems to like the 797, is anyone actually doubting qf wouldnt buy them?

It's hard for me to cheer for the 797, if the specs are unknown. Meanwhile Qantas has been converting A321NEO's to A321LR's and XLR's will be paper work only. The QF NEO backlog is way to large for Jetstar only.

Not doubting that QF won't likely order the 797 (as long as Boeing doesn't make it have too long a sweet spot mission target), but it will also likely replace some of the older (02-04) 737s. The oldest 332s are the domestic config.

The 8 oldest 332s (along with all the 737s) are also getting inflight internet (to Australia's NBN satellite) and the new paint job which would suggest a near term retirement isn't on the horizon.

StTim wrote:

ElroyJetson wrote:

zeke wrote:

In the long tech ops thread we analysed the 787-9 vs the A350-900. In that thread we looked at the same payload over the same distance, for the 40t payload the difference in landing weight was just 4.57%, the trip fuel burn difference on average was less than 1%. The A350-900 being optimised for long haul started to burn less fuel than the 787-9 above 6000 nm.

Looking at Fred’s spreadsheet above the landing weight of the 777-8 will be 207 tonnes, the landing weight of the A350-1000 181 tonnes (assuming 6 tonnes reserve each). That is a delta of 14.42% (207788/181589). Trip fuel is added on top of that.

What Fred has used is a model, not real data, you have to expect it will not be like that in real life. Fred’s model actually exceeds some aircraft limits which would be observed in real life.

We used real data in the tech ops thread to compare the 787-9 to A350-900. That is not being done with the model, anyone making absolute claims based off that just does not understand the limitations of such models.

Also someone else has already gone into some detail to explain effective span on this thread. No need for me to repeat that.

Yes, you arbitrarily picked a payload weight favorable for the A359. The numbers look much different with a 30t or 35t payload.

I showed you the same bias comparing the 778 vs the A351. The 778 can carry 51t payload 1500nm farther.

Choosing conditions to make your argument doesn't make it correct.

From what I understand the payload selected was to match the stated desire from Qantas. No surprise there.

As ever though we on here, even the experts, have less data and poorer models for the frames being proposed than Qantas do. I do wonder why people get so het up about it.

I agree with you. And I believe the 30t payload quoted for Project Sunrise. I also really appreciate the information Fred and others provided. It tells me both the A351 and 778 can do the mission, although each has its particular strengths and weaknesses.

As I have said, I think Qantas can easily justify going with either aircraft.

Anyone else just not buying this ULR stuff? Who would want to sit on an aircraft for THAT long? I mean, I get aviation enthusiasts, but it seems like a bit much..

Veigar wrote:

Anyone else just not buying this ULR stuff? Who would want to sit on an aircraft for THAT long? I mean, I get aviation enthusiasts, but it seems like a bit much..

The people doing it everyday around the world maybe?

Veigar wrote:

Anyone else just not buying this ULR stuff? Who would want to sit on an aircraft for THAT long? I mean, I get aviation enthusiasts, but it seems like a bit much..

Prior to March last year you might have had an arguable point, but the success of the LHR-PER route has rendered it moot. Sydney and Melbourne to London are a gimme at this point. The interesting thing now is how far down QF's route structure the model works. And which metal they choose, of course. Been an eye opening debate (when it got number based), though not sure I'm any the wiser on what will be announced!

my same models as previous with 36t loads.

What size order are people expecting?

To my mind there are probably 5 safe bets for ULH routes (Syd - LHR, Syd - JFK, Syd - DFW, Mel - LHR, Per - LHR). That is 10 aircraft ( + 1 or 2 spares).

Two of those routes (Syd - DFW, Per - LHR) are already served by other aircraft but could probably be better served with Project Sunrise. The current aircraft could be re-purposed for other missions.

I would think a sensible strategy would be:
1) Start with the flagship ULH routes (Syd/Mel - LHR, Syd - LHR).
2) Trial more speculative routes (Mel - JFK, BNE - LHR, Syd - Ord).
3) If any of those routes fail, move the Project Sunrise
aircraft to already proven ULH routes (Per - LHR, Syd - DFW).

Fred,

Can you explain what you mean by missed approach weight and landing weight ?

Thanks

zeke wrote:

Fred,

Can you explain what you mean by missed approach weight and landing weight ?

Thanks

In my original incarnation of the model it works in 3 phases (rightly or wrongly). The main route from the origin to the destination (landing weight), then then assumes that there was a missed approach and a time spent at a given altitude before one more approach( missed approach weight) before a trip to the alternate and landing at 0fuel left. In the example of the project sunrise that we are looking at the QF rules in lead to believe are simply 70mins at 1500ft so I set the alternate to the same as the landing aerodrome and then put the missed approach time as 70mins and missed approach height at 1500ft. There is an artefact in that it does 1second of flying between alternates. My model runs in reverse so starts at DOW plus payload and then adds fuel.

Takeoff weight - missed approach weight = fuel loaded
Takeoff weight - landing weight = fuel used

Hope that makes sense.

Fred


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Thanks Fred, so landing weight -missed approach weight would be holding in a straight line at 1500 ft for 70 minutes (racetrack hold would be an additional 3% more fuel for the turns) ?

zeke wrote:

Thanks Fred, so landing weight -missed approach weight would be holding in a straight line at 1500 ft for 70 minutes (racetrack hold would be an additional 3% more fuel for the turns) ?

Yes, straight line for 70mins, not calculated for turning. I could add 3% or actually calculate it based on the standards is it normally a rate 1 turn? Plus 1 minute straight and level?

Fred


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flipdewaf wrote:

Yes, straight line for 70mins, not calculated for turning. I could add 3% or actually calculate it based on the standards is it normally a rate 1 turn? Plus 1 minute straight and level?

The literal interpretation of the rules means straight line is satisfactory. In reality if your going to hold fir an extended time you would use 10 nm legs and not at 1500 ft. 1500 ft is used as its the worst case holding rate.

flipdewaf wrote:

my same models as previous with 36t loads.

Thanks for the information. Based on your new data at a payload of 36t can both aircraft comfortably fly the mission? Would either aircraft need to block seats with a headwind of say 70 knots versus 20?

Part of the decision for Qantas might be how comfortably each plane can fly the mission with variable conditions. For example, it was rumored the UA's 789 struggled west bound at times on the LAX-SIN route when there were significant headwinds. Could the same fate befall the 778 or A351 at 36t payload on the SYD-LHR route?

flipdewaf wrote:

my same models as previous with 36t loads.

Why are you using DOW weights 8T below OEW for the A350-1000 and then using the actual OEW for the 777-8? Are you trying to making the 777-8 look heavy on purpose?

It is worth noting to save people looking it up themselves that the OEW of the 777-9 is listed at 181T on wikipedia. A straight shrink to 777-8 length brings the OEW to 170T using historic 777 weights. Now this is the weight you are using for your DOW.

The OEW of the A350-1000 is listed as 155-158T on wikipedia yet you are using 147T and 150T for your DOW.

I would use wiki numbers over zeke numbers any day of the week to get a fair apple to apple comparison.

ElroyJetson wrote:

Based on your new data at a payload of 36t can both aircraft comfortably fly the mission?

That table shows only the 777-8 can fly the mission.

If you look at the takeoff weights they are both above the 316T MTOW of the A350-1000. This means they can not carry enough fuel.

So even with the unrealistic empty weight of 147T which is the middle colomn the A350-1000 needs a MTOW of 320T to match the 777-8.

With an empty weight of 150T which is the right column the A350-1000 needs a MTOW of 325T to match the 777-8.

Now a 325T MTOW increase to A350-1000 would cost Airbus a lot of money. Lots of fatigue testing, strengthening and certification work. This would cost more than the entire project sunrise order value. Some would call this putting vanity ahead of profit.

RJMAZ wrote:

So even with the unrealistic empty weight of 147T which is the middle colomn the A350-1000 needs a MTOW of 320T to match the 777-8.

I don't know how unrealistic the 147T empty weight is, but there are plenty of sources that the A351 will have a 3-4 tonne MTOW increase to be delivered in 2020 (cf 316T currently). If it follows the trajectory of other Airbus aircraft 320 tonnes will not be an issue by 2022 - 322T wouldn't be a bad working assumption.

https://www.flightglobal.com/news/artic ... 00-450406/

https://centreforaviation.com/news/qata ... 020-881557

At 316,000kg the A350-1000 is already 7% over her original launch configuration of 295,000kg. Getting another 4,000kg to reach 320,000kg should not be overly complicated.

And with QF now looking at under 300 seats, they won't need 36,000kg of payload capability for SYD-LHR (to be honest, they would not have needed it even at 300 seats).

Per posts on this forum, PER-LHR averages 25,000kg and I would honestly not be surprised if QF is looking at 250 seats or less in four classes so you'd be looking at a similar total payload (revenue cargo is likely going to be minimal due to the carriage cost). So even with a higher DOW than shown in that spreadsheet, a 316,000kg A350 should comfortably be able to do it. And for the shorter Project Sunrise stage lengths, it could either lift more cargo payload or operate at a lower take-off weight to save on fees.

MoKa777 wrote:

You did the calculations for the A350 and 777X a few posts up but may I ask you to break-down the calculation for the 787 effective span? Please.

I just followed the rule of thumb that a raked wingtip adds 80% of the wingtip's length to the physical wingspan, and I roughly assumed a 787's wingtip is 6m on both sides, so its effective wingspan would be 54.12m + 4.8m = 58.92m

Again, those are rough estimations only, and a wind tunnel testing can confirm it.

MoKa777 wrote:

May you please also elabortae a little bit more on the span loading.

Span loading is the complete spanwise pressure distribution of the wingspan, and it can be calculated by dividing weight by span. Before I elaborate further here, I will quickly go through the principle of lift, as understanding it is crucial for grasping the concept of span loading and induced drag.

As air accelerates around the wing, the pressure below the wing will be higher than the pressure above the wing. This difference in pressure generates the lift force that pushes the wings upwards. Now that the pressure at the lower surface is higher than the pressure at the upper surface, what happens at the tips of the wings when the air from the lower and upper side meet? the air will move from the area of the higher pressure to the area of the lower pressure (fluids always flow from higher to lower pressure) in this fashion:



This circular motion of air is caused by the pressure difference between the upper and lower sides of the wings, and that pressure difference is caused by lift. This circular air motion causes changes in the air speed and direction in a way that air circulates around the entire span of the wing, and that simply what is called lift-induced drag. It is the energy consumed in this circular motion, and it is an inherent part of the lift force, as you cannot create lift without having this drag. You can only reduce it.

How to reduce this disturbing motion of air (lift-induced drag)? Reduce span loading. Bring down weight or increase the effective wingspan.

In order to reduce the impact of this circular air motion, you have to make it slower or weaker. Remember this entire motion is generated by the pressure difference between the two sides of the wing, so reducing this pressure difference will reduce the circular motion. How can you reduce the pressure difference? Reduce lift. And how can you do that? Reduce weight.

Another way to make this circular motion slower is to increase its effective wingspan. This will increase spanload distribution for the wing to make the circular air motion around the wing wider and more optimal.


(note: speed and density affect this induced drag as well).

Ok..

So the curved up Boeing winglet reduces the effective wingspan by a 2 metres?

The Airbus slightly sharper curved winglet increases the effective wingspan by 3 metres?

Does anyone else thing that sounds crazy?

Both A350 and 787 winglets have very similar sweep angles when looking from the top down. When looking from the front, both winglets start curving up metres before the end of the wing. The only difference is the 787 wingtip starts curving upwards slightly earlier and the A350 wingtip though starting to curve later it curves up quicker reaching a higher vertical angle.

Eyad89 wrote:

I guess I would cite a few academic peer-reviewed sources since some folks here still don't see what I mean by increasing the effective wingspan over the physical wingspan.

I afraid peer reviewed papers, manufacturers data, and real operational data is not good enough. Apparently wiki is the gold standard

Stitch wrote:

Per posts on this forum, PER-LHR averages 25,000kg and I would honestly not be surprised if QF is looking at 250 seats or less in four classes so you'd be looking at a similar total payload (revenue cargo is likely going to be minimal due to the carriage cost). So even with a higher DOW than shown in that spreadsheet, a 316,000kg A350 should comfortably be able to do it. And for the shorter Project Sunrise stage lengths, it could either lift more cargo payload or operate at a lower take-off weight to save on fees.

The problem is to fly 25,000kg of payload 365 days a year you need headroom. PER-LHR rarely takes off at MTOW. With that 25,000kg of payload it often has around 5000kg of headroom. On a day with bad weather it takes off at MTOW and that headroom is used for extra fuel.

The A350-1000 could not operate the route year round if 25,000kg is the max payload. It will required blocked seats on bad days. The route needs headrooom similar to PER-LHR so 30,000kg of payload is needed to be able to carry 25,000kg every day of the year.

moa999 wrote:

justloveplanes wrote:

Reviewing this, I have to favor Boeing. UA already runs a 789 LAX SYD I think. So the inclusion of the 779 as part of an overall offering provides a more complete solution for QF.

And QF runs 789s BNE-LAX, MEL-LAX, MEL-SFO and soon SYD-SFO

But that's means nothing for a 777 v 350 decision.

The logic is thus

With a 787 / 77X family you cover a wider span of payload / range performance using a common type.

With a 787 / 350 combined fleet, you have two type ratings to support a (slightly) narrower span of payload / range missions.

Since the A35X and 77X appear to be quite close, the decision will hinge on other related benefits, which seem to favor Boeing. Notable that the QF CEO specifically mentioned an A380 replacement as a consideration. A35X would have to be a *lot* better to overcome all this IMHO.

Pretty obvious to see those who understand aerodynamics and those who are fluid dynamics challenged.