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EI321
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 1:12 am

Quoting N328KF (Reply 42):
Well, more properly, it reflects the fact that the A333 is not intended to cover the same sort of distances as the 772/772ER.

Taken from http://en.wikipedia.org

''The 777-200 (772A) was the initial A-market model. The first customer delivery was to United Airlines in May 1995. It is available with a maximum take-off weight (MTOW) from 229 to 247 tonnes and range capability between 3780 and 5150 nautical mile (7000 to 9500 km) ........ The direct Airbus equivalent is the A330-300.''

''The A330-300 was developed as replacement for the A300. It is based on a stretched A300-600 fuselage but with new wings, stabilisers and new fly-by-wire software.
The A330-300 carries 295 passengers in a three-class cabin layout (335 in 2 class and 440 in single class) over a range of 10,500 km (5,650 nautical miles). It has a large cargo capacity, comparable to a Boeing 747. Some airlines run overnight cargo-only flights after daytime passenger services.
........The direct Boeing equivalent is the 777-200.''


The A333 does not have the range of a 772ER but in fact has greater range than a normal 772.
 
widebodyphotog
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 1:23 am

Quoting Zeke (Reply 48):
The average stage length across the entire US 772 fleet was 3,812 nm for the 333 fleet 3,662 nm, 150 nm stage length does not explain the differance.

Yes but the number of stages and the composition of stage lengths is wildly different. 124 airplanes making 1.6 departures per day and a utilization of 12.4h of same is far far more than 22 airplanes at 1.8 and 14.1h. The lower departure number for 777 is indicative of the fact that there are a number of 777's included that are running segments much longer than the overall average. I mean who are we kidding here? This data includes CO EWR-HKG service as well as AA and UA Trans-Pacific service ex JFK, ORD and the US West coast. At the opposite end of the spectrum short range and US transcon 777 service is included. All compared to A330 international operations by US and NW? Like I said, oranges to tangerines and peaches to nectarines...



-widebodyphotog
 
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N328KF
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 1:28 am

Quoting EI321 (Reply 50):
''The 777-200 (772A) was the initial A-market model. The first customer delivery was to United Airlines in May 1995. It is available with a maximum take-off weight (MTOW) from 229 to 247 tonnes and range capability between 3780 and 5150 nautical mile (7000 to 9500 km) ........ The direct Airbus equivalent is the A330-300.''

I'm well aware of that paragraph. You see, I wrote it.
 
CptGermany
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 1:56 am

Quoting Kappel (Reply 49):
Well, the -300 came first, and Airbus than shrank it to the -200.

I didn't know. Thanks.  veryhappy 
 
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zeke
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 2:07 am

Quoting Widebodyphotog (Reply 51):
Yes but the number of stages and the composition of stage lengths is wildly different. 124 airplanes making 1.6 departures per day and a utilization of 12.4h of same is far far more than 22 airplanes at 1.8 and 14.1h.

A larger fleet should be cheaper than a smaller fleet, espically on a maintenance front where spares for a fleet can be spread over a larger number of aircraft.

Quoting Widebodyphotog (Reply 51):
This data includes CO EWR-HKG service as well as AA and UA Trans-Pacific service ex JFK, ORD and the US West coast. At the opposite end of the spectrum short range and US transcon 777 service is included. All compared to A330 international operations by US and NW?

They are the actual average (short and long flights will counter each other out), so the actual situation on average the 333 is more efficient to operate over a 772. This agree with the comments made in post 1...

Quoting Macc (Thread starter):
According to him, the 330 is more fuel efficient than 777.
.......
All in all, most of the station managers tried to get the 777 but now are happy to get the 330 due to significant lower "operating" costs. This however is not so much due to the fuel consumption but due to the fact that purchasing / leasing costs are partially included into the calculating. And obviously the 777 are at least for this airline more expensive than the 330.

The vast majority of all flights done by this class of aircraft worldwide is less than 4000 nm in stage length, so the numbers listed as US averages are fairly representative of worldwide trends.

If you were to compare the 772 and 744 over a longer stage length, one can see why the 772 has replaced the 744.
 
787engineer
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 2:34 am

Quoting Byronsterk (Reply 21):
Well i seriously doubt anyone will fully load the 773.... however somehow (really i don't know why) i think the a330 fuly loaded is better then a 773 fully loaded....

What would make you think that? The 773 would beat the A330 hands down if each were fully loaded, just like a fully loaded 767 would beat a A320. The larger the plane, the better the CASM assuming similar level of technology and pax density.

Quoting Thorben (Reply 26):

I think it is better to compare typical missions than extreme scenarios. Boeing with its comparison of the 773ER and the A346 forgot to add: "under this and this and this and this and this and this condition". If you compare normal missions, things look a lot different.

Who's comparing extreme scenarios? "Nomral scenarios" is different for each airline. It's funny how you automatically assume that since NW determined that the A333 was the right airplane for them, they're the experts in evaluating airplanes. BA, and SQ must not know what they're doing when they order those 772s.  sarcastic 

Quoting Thorben (Reply 13):

But the A330 is a size bigger than the 767.

The A333 is but the A332 matches up very well with the 764 (only about 10 pax difference in 3 class config). Let's try not to lump together families and split them whenever one way suits your argument better.

Quoting Thorben (Reply 15):
Or 10,170 km. What is that? A short-hop? How much range does the 772A have?

Why don't you look it up yourself? 10,170km isn't a short-hop but it isn't all that long compared to 772ER. The 772A was the first cut, and I'm sure the first 50 or so A330 weren't nearly as efficient as the later models. The 772ER would be a better comparison than the 772A; it has a range of 14,316 km, weighs 50,000kg more, and performs the mission that it was originally intended for: long range, 300+ pax airliner. That simply goes to show how much extra structure the 772A was carrying around.

Quoting Aviator27 (Reply 33):
This is fact. Period. If you're confused, go take a class on aerodynamics.

I don't know about you, but I've taken a class on aerodynamics in fact I've taken more than one  Wink. Frankly, I think you're confused, if anything hanging two extra engines on the wing makes it less aerodynamically efficient of a wing. You're also increasing the cross sectional area with four mid to large size engines than two really big ones with the same total thrust. Not to mention the increase in interference and skin friction drag increase. Aerodynamically two engines are better than four, and as far as total TSFC two big engines is better than four small engines in most cases, considering they total the same amount of thrust and have about the same level of technology.
 
widebodyphotog
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 2:49 am

Quoting Zeke (Reply 54):
They are the actual average (short and long flights will counter each other out), so the actual situation on average the 333 is more efficient to operate over a 772. This agree with the comments made in post 1...

If they are a mathematical average then the result is not representative of the disparate 777 operations and not a good comparison even for fleetwide operations. The the longest 777 segments are up to 3,000nm longer than the longest A330 segments the data represents and those longer 777 segments represent total aircraft utilization that is greater than the entire A330 fleet ops. The A330 segments are basically all the same length and you're comparing fleetwide operations for 777 and A330 that include a high numer of segments that the A330 can not operate and a high number of segments that the A330 does not operate. The comparison puts narrowly defined A330 ops up against the entire spectrum of 777-200 ops...not a good comparison at all.

As I said before in this narrowly defined segment of A330 operation it is more efficient than the average of the entire 777-200 fleet operation which includes segments from 500 miles to 8,000 miles. But that does not say much other than that. How does the 777-200 compare head to head over the same markets? There is a much smaller disparity, I assure you.



-widebodyphotog
 
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zeke
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 3:13 am

Quoting Widebodyphotog (Reply 56):
As I said before in this narrowly defined segment of A330 operation it is more efficient than the average of the entire 777-200 fleet operation which includes segments from 500 miles to 8,000 miles. But that does not say much other than that. How does the 777-200 compare head to head over the same markets? There is a much smaller disparity, I assure you.

Incorrect, this is a valid comparison of _all_ 333 and 772 operations in the US.

If fleet planning or other operational requirements mean that an airline is using a short sector and a longer sector fleet wide to get the required utilization, so be it, it is still valid.

I don't understand your point, this is historical data being provided by US carriers of their actual costs, actual fuel burns, actual cabin seating, and their actual market.

It is not manufacturers gloss to skew one product over another of a stage length or configuration which provides a gross disparity which would be difficult to repeat in service.
 
widebodyphotog
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 3:18 am

Quoting 787engineer (Reply 55):
I don't know about you, but I've taken a class on aerodynamics in fact I've taken more than one . Frankly, I think you're confused, if anything hanging two extra engines on the wing makes it less aerodynamically efficient of a wing. You're also increasing the cross sectional area with four mid to large size engines than two really big ones with the same total thrust. Not to mention the increase in interference and skin friction drag increase. Aerodynamically two engines are better than four, and as far as total TSFC two big engines is better than four small engines in most cases, considering they total the same amount of thrust and have about the same level of technology.

I'll agree and add...Thrust is thrust and for a theoretical comparison were all things are "equal" the number of engines would not change any properties of the airframe. The only thing that would matter is the SFC of the engines and if those were the same, and the thrust requirement is the same, then TSFC of the airframe/powerplant combination would be the same and it would not matter what the number of engines was. For four engines to make a difference over two engines on the same airframe the additional two engines would have to change the aerodynamics of the airframe and/or the four engines would have to have better uninstalled efficiency than the pair.

In general larger engines with their higher BPR, OPR, and FPR's are more efficient than smaller engines even if the smaller engines have the same values. Bigger fans and blades are more efficient at extracting energy from and imparting energy to a fluid such as air if the molecules don't change size, which for air and hot burning gases combined with air, they don't.

However, TSFC is a different thing altogether though and I'm still waiting to find out how doing nothing other than changing the number of engines increases the efficiency of the engine/airframe combination...



-widebdyphotog
 
atmx2000
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 3:26 am

Quoting Zeke (Reply 39):
Cost per Block hour / Lease rental capital cost per month/Gal of fuel per hour/Seats
762 $4,132/$158,798/1,408/180
763 $4,901/$321,000/1,568/216
772 $6,331/$366,543/2,159/257
333 $4,891/$243,357/1,871/271

The above divided by the number of seats

762/$22.95/$882/7.82
763/$22.68/$1486/7.25
772/$24.63/$1426/8.40
333/$18.04/$897/6.90

Seems extremely misleading to me to combine 772A and 772ER figures, and non ER and ER versions of the 767 in a single figure. Also where are the A332 figures?

The fact that the 772's are configured with fewer seats than the A333 suggests that the aircraft are being used in very different ways.
 
widebodyphotog
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 3:43 am

Quoting Zeke (Reply 57):
I don't understand your point, this is historical data being provided by US carriers of their actual costs, actual fuel burns, actual cabin seating, and their actual market.

I'm not disputing the validity of the data, I am very familiar with Form 41 data, I am argueing against your representation of the data based on the actual operational costs of the fleet operation. In your comparison it's suggested that a 777-200ER on JFK-NRT can be compared to an A330-300 on CLT-LHR or the like, which is what the average fuel burns/capital cost/utilization suggests. The comparison is not valid on that basis. Calculated data such as cost per ASM or ton/mile figures for freighters is a much more substantial measure of efficiency of fleet utilization across disparate segments and on that basis the the 777-200 does as good or better in comparison to the A330.


-widebodyphotog

[Edited 2006-04-06 20:45:31]
 
Pihero
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 4:55 am

Quoting Stitch (Reply 35):
Per Widebodyphotog:

772ER Max Payload: 135,000lbs
A333 Max Payload: 49,000lbs

772ER Max Payload with Max Fuel: 112,000lbs
A333 Max Payload with Max Fuel: 66,000lbs

Somehow, these figures don't add up, and yet everybody is using them.
As someone would say : "Curiouser and curiouser..." said Alice.

Quoting 787engineer (Reply 55):
don't know about you, but I've taken a class on aerodynamics in fact I've taken more than one . Frankly, I think you're confused, if anything hanging two extra engines on the wing makes it less aerodynamically efficient of a wing. You're also increasing the cross sectional area with four mid to large size engines than two really big ones with the same total thrust. Not to mention the increase in interference and skin friction drag increase. Aerodynamically two engines are better than four, and as far as total TSFC two big engines is better than four small engines in most cases, considering they total the same amount of thrust and have about the same level of technology.

You might know about aerodynamics, but you are showing a modicum of ignorance about performance.The required installed thrust on a quad is always less than a twin's.
And then you seem strangely unaware of the effect of moment bending on a quad, due to the installation of the engines so far toward the wing tip...the consequence of which is a better ZFW for a quad...
Please be nice to others.
 
Thorben
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 5:54 am

Quoting Aviator27 (Reply 33):
There us a stupid idea going around on A-NET that a twin is more fuel efficient than a quad engine airplane. ALL things being equal, given the same airplane and weight, four engines have a better thrust specific fuel consumption than two engines.

Finally, one who clarifies it.

Quoting Aviator27 (Reply 33):
all you 15 year old aircraft engineers and airline operations executives.

Priceless!  thumbsup 

Quoting Aviator27 (Reply 33):
That being said, the B777 and A340 aren't the same airplanes. They have different weights and are different sizes. So its like compare apples and oranges.

That explaines why some airlines operate both types.
 
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zeke
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 5:56 am

Quoting Atmx2000 (Reply 59):
Seems extremely misleading to me to combine 772A and 772ER figures, and non ER and ER versions of the 767 in a single figure. Also where are the A332 figures?

This is not my data, have a look at that thread in Tech Ops for further details. I understand the data comes straight from the carriers.

It maybe misleading to you, however its what the carriers are actually paying.

The seating configurations are the industry average for the entire fleet.

As for seating and predicted burns this is what they throught .....

Quoting Jano (Reply 7):
This is not necessarily apparent if one looks from the generic marketing material from Boeing because the range of the 777-200, evaluated with Northwest rules and interiors, is approximately 1,100 miles less than advertised.

The 777 can carry more seats than the A330 although the A330 already carries 29 more seats than our current DC-10-30s. The optimal 777-200 configuration we modeled had 27 more seats tahn the A330-300 (329-302) and 56 seats more than the DC-10-30 (329-273). However, these additional seats were economy seats taht typically would be filled with lower yielding passengers.

The 777 has the same empty weight for all available MTOW's (580,000-656,000 lbs). Northwest requires only the lowest weight for nearly all markets, roughly comparable to the A330. The net result to Northwest is that the 777 is more than 41,000 pounds heavier than the A330 yet provides minimal additional revenue capacity.

The heavier weight of the 777 translates directly into a fuel burn penalty. On a typical 3,500 nm mission, the A330 burns approximately 28% less fuel tahn a DC-10-30; accounting for its higher seating capacity, it burns 35% less on a per seat basis. The much heavier 777 burns approximately 16% more fuel than the A330 on a per trip basis, and 6% more on a per seat basis.

332 data, not sure if its included in the table, should be 27 330s in the USA at the moment.

Quoting Widebodyphotog (Reply 60):
In your comparison it's suggested that a 777-200ER on JFK-NRT can be compared to an A330-300 on CLT-LHR or the like, which is what the average fuel burns/capital cost/utilization suggests. The comparison is not valid on that basis. Calculated data such as cost per ASM or ton/mile figures for freighters is a much more substantial measure of efficiency of fleet utilization across disparate segments and on that basis the the 777-200 does as good or better in comparison to the A330.

From the same data Total Aircraft Operating Cost Per ASM

777 - 5.1
330 - 3.8

So I take it that is a "substantial measure of efficiency" of the 330 over the 777 ?
 
tigerotor77w
Posts: 198
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 6:16 am

Quoting Thorben (Reply 62):
Quoting Aviator27 (Reply 33):
There us a stupid idea going around on A-NET that a twin is more fuel efficient than a quad engine airplane. ALL things being equal, given the same airplane and weight, four engines have a better thrust specific fuel consumption than two engines.

Finally, one who clarifies it.

I haven't made the claim, but why does the quad have better operating economics (or am I wrong to use operating economics to begin with)... forgive me as I have not taken an aerodynamics or strictly-mechanical engineering classes (sophomore in mech. engr = long way to go yet).
 
flydreamliner
Posts: 1928
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 6:36 am

Quoting LukasMako (Reply 31):
Well,
Then how is it possible that UA uses their 777-200non-ER on Transatlantic flights and their 777-200ER on Asian and Australian flights without any problems. They are all PW4000 powered.

UA doesn't opperate any non-stop north American flights to Australia on a 777, and a 772 non-Er would never make it. Also, for Asian routes, UA can fly out of their hub at SFO. Northwest opperates nearly all their pacific flights out of MSP and DTW, which are almost 2,000 miles further than SFO. A 772 non-ER couldn't do ORD-NRT, MSP-NRT, or DTW-NRT without a tech stop. a 772ER could, but still.

Quoting Aviator27 (Reply 33):
There us a stupid idea going around on A-NET that a twin is more fuel efficient than a quad engine airplane. ALL things being equal, given the same airplane and weight, four engines have a better thrust specific fuel consumption than two engines.

To break it down for all you 15 year old aircraft engineers and airline operations executives. Four engines is more fuel efficient than two engines. Period.

I can't seem to think of an example where that is true..... Or a single reason why that would be true. The number of engines has nothing to do with the efficiency of the engines. The difference is more drag and weight out on the wing, and that is not efficient. Don't tell me an extra engine out on each wing isn't more drag and weight.

And if you were right (but you're not), why would Boeing and Airbus switch over to twin engines? Why would an A330 burn less fuel per mile than an A340 which is the same aircraft, but with four engines, and why is A350 not going to keep going with 4 engines?

4 are not better than 2. It's sad you need opperations execs and 15 year old engineers to tell you that. Period.

Quoting Widebodyphotog (Reply 40):
So if you replace two GE90-115's on a 777-300ER with a quartet of PW JT9D-7's it going to give the aircraft better range performance??

I'm pretty sure JT9D-7 is one of the least efficient engines to go on a widebody and GE90 is one of the most efficient. I think you could probably put 4 GE90s on there and still get better burn rates than 4 JT9D-7s  Smile

Can anyone answer me this..... if they loved A330 so much, why didn't they buy A333's or A350's to do their pacific opps instead of 787s?

A330 is better suited for NW's light transatlantic routes than 777. There is a reason UA, AA, AF, CO, AZ, DL, and more fly the 777 across the Atlantic. It's the better plane for what they need it for. For NW and US Airways, they find the A330 does what they need better. They both opperate mixed fleets (but have been buying more Airbus lately)
 
PlaneHunter
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 6:45 am

Quoting Thorben (Reply 26):
I think it is better to compare typical missions than extreme scenarios. Boeing with its comparison of the 773ER and the A346 forgot to add: "under this and this and this and this and this and this condition". If you compare normal missions, things look a lot different.

"Things" look particularly a lot different in the respective order books...

Quoting Thorben (Reply 62):
That explaines why some airlines operate both types.

Which ones are you referring to specifically?

Quoting Thorben (Reply 62):
Finally, one who clarifies it.

And how do you explain that twins outsell quads?


PH
 
trex8
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 6:48 am

Quoting FlyDreamliner (Reply 65):
Can anyone answer me this..... if they loved A330 so much, why didn't they buy A333's or A350's to do their pacific opps instead of 787s?

well clearly a A333 is not optimal for transpac flights and NW AFAIK use A332s only for transpac.
they clearly felt the 787 was a better bet than the A350 for whatever reason, better assumed economics, sooner delivery times, who knows. but for those who feel they were misguided in choosing the A330, maybe they are just as misguided this time choosing the 787! Smile
 
flydreamliner
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 7:10 am

I said for what NW needed, A330 was superior. I merely used the 787 example to prove A330 isn't an infallible product that is better than 777 in ever situation. It's not.
 
widebodyphotog
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 7:33 am

Quoting Pihero (Reply 61):
You might know about aerodynamics, but you are showing a modicum of ignorance about performance.The required installed thrust on a quad is always less than a twin's.

The required thrust for a twin is a matter of regulation and not aerodynamics. That increased proportion of thrust is to provide an operational margin of safety for engine out performance at various stages of the operating envelope. But just because the level of thrust in increased does not automatically induce higher TSFC. The specific relationship of fuel to thrust production does not change simply because you need more at any given stage of flight. The number of engines does not change the thermodynamic efficiencies of those engines, the size of the engine does, but not the number. In point of fact for engines of the modern era the higher the thrust, larger the engine, the lower the expense in terms of fuel it is to produce. If it was the opposite then we'd have a lot of airplanes with six or eight little engines flying very efficiently all over the world...

Quoting Pihero (Reply 61):
And then you seem strangely unaware of the effect of moment bending on a quad, due to the installation of the engines so far toward the wing tip...the consequence of which is a better ZFW for a quad...
Please be nice to others.

Do you mean that the outboard engines on a quad provide more bending relief than the engines on a twin? Yes of course but for a given wing and weight of aircraft the load is the same and you compensate for it in terms of stronger structure in the required area for the twin, or the weight of the outboard engines for the quad. Again all things being equal there is equal bending loads and they are compensated for up to the structural margins of the aircraft. Changes in bending moments increase or decrease the effective angles of incidence for the wing and may have a drag penalty depending on that wings aero properties. (In reality twins wings bend a lot less because they are not as highly loaded, read that mass/wing area, due mainly to the fact that they are much lighter than comparable quads) But for this to make the difference in TSFC between twins and quads there would have to be different uncompensated bending loads between our two aircraft of equal weight, size, speed and capacity. Why would that be?

And what is better ZFW mean? Lower? In theoretical terms why would the ZFW, structure plus payload, be lower for a quad than for a twin? What is it about theoretical four engined aircraft that makes ZFW "better"? Furthermore In practical terms what example is there of a quad that has a lower mission ZFW with equal payload than, equal or lower takeoff weight to, and can fly longer distances than a twin?




-widebodyphotog
 
787engineer
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 8:27 am

Well said, widebodyphtog, I couldn't have said it better myself. Larger engines (turbofans) are naturally more efficient because of their higher bypass ratios. A higher bypass engine generally has a higher propulsive efficiency. Why do you think most modern airliners have as big of a turbofan that they can reasonably fit under the wing? The 737 went from those small relatively low bypass engines (-100/-200) to what we see today. Of course there are limitations; large fans always have concerns that the tips will go supersonic (one reason why turboprops are slower than jets).

So for an equal amount of thrust two big engines with huge fans will be more efficient than four medium engines. However as you said a twin needs to factor in the engine-out scenario, but that just means once in cruise the pilot could throttle back the mixture and RPMs and rely more on that big fan which is very efficient at providing thrust. I'm not sure if a quad would necessarily have lower ZFW than a twin, you'll have to explain that one to me.
 
widebodyphotog
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 8:29 am

Quoting Zeke (Reply 63):
So I take it that is a "substantial measure of efficiency" of the 330 over the 777 ?

Sure, and what it means is that the A330 fleet operates with a lower cost per ASM on 3,000-4,000nm segments than does the 777-200 subtypes on 400-7,000nm segments. Who's denying that? But that's all it means. The segments that the A330 is operated on by US carriers are basically all the same length. The only conclusion I can glean from that is that going by this representation of specific cost alone it may have been a better idea for the US domestic carriers to purchase subfleets of A330's to do shorter range international segments. However the CASM fighure for 777-200 is skewed by including the entire range of stage lengths relative to the A330's which are all quite close in distance...

By your suggestion there is no difference in CASM for different stage lengths using different sub types of 777-200, and that the A330 CASM would be static for 400nm segments as well as 7,000nm segments, which it can not do BTW. Unfortunately we do not have a complete picture here for two reasons. First the US domestics operate A330's on a limited number of lanes that are similar in length, and secondly there are no domestic operators of the A340 to fill in the analysis for longer segments. So what are we comparing? Airplanes that are up to 150,000lbs heavier, on much longer segments, nearly equal weights on similar segments, and lower weights on very short segments against aircraft that are all pretty much the same on a very narrow range of flight distances...

C'mon Zeke you're a smart guy. Are you really suggesting that the 777-200 has a blanket 34% greater specific operating costs than the A330?

Quoting Stitch (Reply 35):
Per Widebodyphotog:

772ER Max Payload: 135,000lbs
A333 Max Payload: 49,000lbs

772ER Max Payload with Max Fuel: 112,000lbs
A333 Max Payload with Max Fuel: 66,000lbs

Let me correct you there:

A330-300 max structural payload is 102,200lbs for the generic airplane
A330-300 Max payload with Max fuel (FD=6.7) is 54,600lbs

777-200ER Max payload with Max fuel (FD=6.7) is 48,500lbs

Rounded to the nearest hundred pounds



-widebodyphotog
 
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Stitch
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 9:38 am

Do you perchance have a newer master_weight_data.gif file? The data I posted was pulled from that file, but I've had it for awhile so it may be out of date.
 
Pihero
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 10:11 am

Widebodyphotog,
-My post was just pointing at misconceptions which lead to wrong conclusions :
-That a quad and a twin with similar weight and configs would have the same installed thrust. Wrong. For two reasons :
1/-Because the loss of an engine leaves the quad with 75% of thrust, versus 50 for a twin.
2/-Because the drag of a failed engine on a twin is more than twice greater than one on a quad.
So, you see, The "matter of regulations" as you call it translates into a matter of aerodynamics.

Secondly, and see figures for the 330 vs 340, the 340 has a higher ZFW than a twin, and it's just because of the bending moment of the outboard engines.In theory, the higher the bending moment, the higher the ZFW and the lighter the needed wing structure.
Another good example is the 1011 vs the DC-10 . With very similar geometries, the Tristar has a higher ZFW because the engines are so much farther out (they are also quite heavier).

Thirdly

Quoting Widebodyphotog (Reply 69):
The number of engines does not change the thermodynamic efficiencies of those engines, the size of the engine does, but not the number

I beg to differ.The thermodynamic efficiency has nothing to do with the size.It has to do with the characteristics of the core :pressure and temperature . Granted, the propulsive efficiency is related to the by-pass ratio. As you know, the best efficiency, in terms of thermodynamics is reached fairly high in the RPM regimes, so basically, there is a balance somewhere in these respective cycles : a core that's running at or close to its peak efficiency linked to a slightly less efficient fan (quad) or a core that's below its most efficient regime with a fan that's more efficient (twin).
As usual, things are a little bit more complicated than one can see.
Of course, being completely truthful, I have to add that the twin, using its available thrust would climb higher, reaching better altitudes...which makes comparisons even more interesting.

Quoting 787engineer (Reply 70):
that just means once in cruise the pilot could throttle back the mixture and RPMs and rely more on that big fan which is very efficient at providing thrust

That's exactly the misconception I talked about, even forgetting that the pilot of a modern jet has no control of the "mixture".

Lastly, comparisons are moot. Just accept that an airline has chosen one airplane and not the other because it suited their operations better. The ideal situation would be to tailor a fleet as close as possible to the best efficiency of each airplane, depending on the route, the traffic load, the performance constraints, the amount of cargo possible.................etc... etc...
Some airlines manage to do it quite well.

Thank you for correcting the data somone quoted from you. It bugged me that so many posters related to a set of incorrect infos.

Regards
 
widebodyphotog
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 11:23 am

Quoting Pihero (Reply 73):
-My post was just pointing at misconceptions which lead to wrong conclusions :
-That a quad and a twin with similar weight and configs would have the same installed thrust. Wrong. For two reasons :
1/-Because the loss of an engine leaves the quad with 75% of thrust, versus 50 for a twin.
2/-Because the drag of a failed engine on a twin is more than twice greater than one on a quad.
So, you see, The "matter of regulations" as you call it translates into a matter of aerodynamics.

What, in the world does that have to do with this?

Quoting Aviator27 (Reply 33):
There us a stupid idea going around on A-NET that a twin is more fuel efficient than a quad engine airplane. ALL things being equal, given the same airplane and weight, four engines have a better thrust specific fuel consumption than two engines.

To break it down for all you 15 year old aircraft engineers and airline operations executives. Four engines is more fuel efficient than two engines. Period.

He did not say that during an engine out scenario TSFC was higher. The point I am opposing is the above. And no one has given a demonstrable answer on how lower TSFC is an inherent property of aircraft having more engines. Further more a higher level of thrust is not indicative of higher TSFC. For example, the A340-500 has lower TSFC than the 777-200LR through portions of it's design payload range envelope. So what, the thrust requirement is greater in proportion to the difference in TSFC so the fuel burn is greater in total. This has nothing to do with having four engines. It has to do with the properties of the A340-500 wing through certain specific conditions.

Quoting Pihero (Reply 73):
Secondly, and see figures for the 330 vs 340, the 340 has a higher ZFW than a twin, and it's just because of the bending moment of the outboard engines.In theory, the higher the bending moment, the higher the ZFW and the lighter the needed wing structure.
Another good example is the 1011 vs the DC-10 . With very similar geometries, the Tristar has a higher ZFW because the engines are so much farther out (they are also quite heavier)

Huh? So in other words structural payload capability increases because wing loading and subsequently bending loads increase? But the A340-300 has a lower structural payload limit than the A330-300 and the ZFW relative to structural weight is worse in terms of structural efficiency...The structure of the A340-300 is heavier than the A330-300 because the former requires a heavier structure to carry the higher mass fraction of fuel for longer range included in 100,000lbs of higher takeoff weight...What you're saying is absolutely opposite of reality. In theory the structure of a wing can be made lighter because the weight of engines placed further out on the wing provide greater bending relief. So in theory a quad's wings would be lighter than a twins...for the same total mass of aircraft...

BTW The Tristar was not heavier than the DC-10 because the engines were placed further outboard. The L-1011 wing had reduced bending loads from the combination of having the engines further outboard and incorporating an active gust alleviation system. This lower gust loading and higher passive bending relief was a principle feature that allowed the airplane to have up to 25,000lbs lower structural weight than the comparable DC-10 model...

have I stepped into bizzaro world where up is down and down is up???...

I'm operating from the constraints of Aviator27's comments and trying to understand what inherent aerodynamic property of having more engines on a wing reduces TSFC for the same airframe. Still, no answer...

Quoting Stitch (Reply 72):
Do you perchance have a newer master_weight_data.gif file? The data I posted was pulled from that file, but I've had it for awhile so it may be out of date.

Have not changed that file since January 2nd. Some of the info is not up to date but in-production aircraft information is current.



-widebodyphotog

[Edited 2006-04-07 04:30:05]
 
widebodyphotog
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 11:53 am

Quoting Pihero (Reply 73):
I beg to differ.The thermodynamic efficiency has nothing to do with the size.It has to do with the characteristics of the core :pressure and temperature . Granted, the propulsive efficiency is related to the by-pass ratio. As you know, the best efficiency, in terms of thermodynamics is reached fairly high in the RPM regimes, so basically, there is a balance somewhere in these respective cycles : a core that's running at or close to its peak efficiency linked to a slightly less efficient fan (quad) or a core that's below its most efficient regime with a fan that's more efficient (twin).
As usual, things are a little bit more complicated than one can see.
Of course, being completely truthful, I have to add that the twin, using its available thrust would climb higher, reaching better altitudes...which makes comparisons even more interesting.

But this is a false assumption that four engined aircraft cores are linked to less efficient fans and twins are linked to more efficient fans. Especially when taking into account Three spool engines like the Trent 900 and Trent 500 where spool efficiencies are ostensibly more closely matched. It is not an inherent property of twins to have more efficient fans...I mean the 747 and 767 have the exact-same-engines...

Thermodynamic efficiency in terms of turbomachinery is the measure of efficiency in converting fuel/air mass flow into useful work or thrust. Larger engines have higher OPR, which means reduced work on the combustor to make the required TET, lower FPR, reduced fan horsepower requirement to move a given mass of air, and higher BPR, greater proportion of air that does not undergo severe thermodynamic cycle. Taken in combination with the fact that air molecules do not increase in size, kinematic viscosity does not increase, which yeilds lower reynolds flow values because the bits moving air and what the air is moving through is larger, thermodynamics of larger engines is inherently better.


GE has a great technical publication on GE90 that goes through a lot of this chapter and verse, I'll try to dig it up, but now we are really getting off topic here...




widebodyphotog
 
MD-90
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 11:57 am

Quoting Macc (Thread starter):
All in all, most of the station managers tried to get the 777 but now are happy to get the 330 due to significant lower "operating" costs. This however is not so much due to the fuel consumption but due to the fact that purchasing / leasing costs are partially included into the calculating.

I figured that would bring the pro-Airbus camp out spoiling for a fight, but it hasn't. Kudos.
 
OlegShv
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 12:24 pm

Quoting Aviator27 (Reply 33):
ALL things being equal, given the same airplane and weight, four engines have a better thrust specific fuel consumption than two engines.

Holy cow!  eyepopping  You should patent that idea and sell it to Boeing and Airbus. I'm sure they will find a way to fit even 8 engines on an airframe  Big grin

For starters, TSFC has nothing to do with the airframe. It's a characteristic of a particular engine operating in certain environmental conditions. Formal definition:
TSFC=(lb fuel) / (lb thrust * time)

As has been said by Widebodyphotog and 787engineer, there are many factors that will affect efficiency of the airframe with 2 vs. 4 engines. Keep in mind that larger sized engines are usually sigificantly more efficient.

Quoting Widebodyphotog (Reply 58):
However, TSFC is a different thing altogether though and I'm still waiting to find out how doing nothing other than changing the number of engines increases the efficiency of the engine/airframe combination...



Quoting Pihero (Reply 73):
As usual, things are a little bit more complicated than one can see.
Of course, being completely truthful, I have to add that the twin, using its available thrust would climb higher, reaching better altitudes...which makes comparisons even more interesting.



Quoting Pihero (Reply 73):
Lastly, comparisons are moot. Just accept that an airline has chosen one airplane and not the other because it suited their operations better. The ideal situation would be to tailor a fleet as close as possible to the best efficiency of each airplane, depending on the route, the traffic load, the performance constraints, the amount of cargo possible.................etc... etc...
Some airlines manage to do it quite well.

Totally agree!  Smile
 
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zeke
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 12:38 pm

Quoting 787engineer (Reply 70):
Well said, widebodyphtog, I couldn't have said it better myself. Larger engines (turbofans) are naturally more efficient because of their higher bypass ratios. A higher bypass engine generally has a higher propulsive efficiency. Why do you think most modern airliners have as big of a turbofan that they can reasonably fit under the wing? The 737 went from those small relatively low bypass engines (-100/-200) to what we see today. Of course there are limitations; large fans always have concerns that the tips will go supersonic (one reason why turboprops are slower than jets).

Consider a CF6-80-C2 with a BR of 5.31, at takeoff around 52,500 lbf, cruise 6,600 lbf, TSFC 0.545.

A CFM56-5C with a BR of 6.60, at takeoff around 31,200 lbf, cruise 12,000 lbf, TSFC 0.576.

The only thing I can say with powerplant development, is that aircraft with the later generation powerplant, everything else being equal has the performance advantage.

Quoting 787engineer (Reply 70):
So for an equal amount of thrust two big engines with huge fans will be more efficient than four medium engines. However as you said a twin needs to factor in the engine-out scenario, but that just means once in cruise the pilot could throttle back the mixture and RPMs and rely more on that big fan which is very efficient at providing thrust. I'm not sure if a quad would necessarily have lower ZFW than a twin, you'll have to explain that one to me.

"mixture and RPMs", not in a jet.

Quoting Widebodyphotog (Reply 71):
The only conclusion I can glean from that is that going by this representation of specific cost alone it may have been a better idea for the US domestic carriers to purchase subfleets of A330's to do shorter range international segments. However the CASM fighure for 777-200 is skewed by including the entire range of stage lengths relative to the A330's which are all quite close in distance...

Yes I agree, the 772 is not best suited for some of the routes its being used for, and the Boeing numbers do not stack up on short sectors. This is something which has been known in industry for some time, however on a.net the opposite is considered true.

Quoting Widebodyphotog (Reply 71):
By your suggestion there is no difference in CASM for different stage lengths using different sub types of 777-200, and that the A330 CASM would be static for 400nm segments as well as 7,000nm segments, which it can not do BTW.

The majority of flights for this class of aircraft is below 4000 nm, do I understand you correctly that in your view the 330 is a better machine over that stage length ?

Quoting Widebodyphotog (Reply 71):
C'mon Zeke you're a smart guy. Are you really suggesting that the 777-200 has a blanket 34% greater specific operating costs than the A330?

No I don't, I think its well optimised for the role it was designed for. A 7000 nm stage length aircraft would be the 343, not 333.

Quoting Pihero (Reply 73):
Secondly, and see figures for the 330 vs 340, the 340 has a higher ZFW than a twin, and it's just because of the bending moment of the outboard engines.In theory, the higher the bending moment, the higher the ZFW and the lighter the needed wing structure.

The 343 on takeoff is a lot heavier than then 333, the additional mass of fuel in the aircraft has bending moment relief of the outer engines, thus allowing for a lighter wing, sharing 90% structural commonality with the 333 wing.

Quoting Widebodyphotog (Reply 74):
He did not say that during an engine out scenario TSFC was higher. The point I am opposing is the above. And no one has given a demonstrable answer on how lower TSFC is an inherent property of aircraft having more engines.

What is important is that the aircraft has the installed thrust onbord for OEI takeoff, and in cruise all engine operating, if an aircraft has more thrust than is needed for either scenario, it has additional mass on the wing that does not need to be there, and burning fuel to carry that extra unnecessary mass.

Quoting Widebodyphotog (Reply 74):
Further more a higher level of thrust is not indicative of higher TSFC. For example, the A340-500 has lower TSFC than the 777-200LR through portions of it's design payload range envelope.

I think your mistaken, the Trent 500 does not have a lower TSFC than that of the GE90-115B. You put the Trent 1700 derivative powerplant on the 345 with a much improved TSFC it will have better operating economics than that of the 772LR.

As shown on other threads, the 748i has better operating economics over the 773ER, the major difference is the TSFC, the wing design is not changing all that much.

Quoting Widebodyphotog (Reply 74):
In theory the structure of a wing can be made lighter because the weight of engines placed further out on the wing provide greater bending relief. So in theory a quad's wings would be lighter than a twins...for the same total mass of aircraft...

This is correct, a quad that has the same mass, with the same TFSC engines as a comparable twin will have a lighter wing.

333 OEW is about 8t lighter than the 343, however the 343 has a 50t heavier MTOW, and longer range. They share 90 commonality between the two models with their wings, the outboard engine allow for a lighter wing, and improved OEI climb gradient over its 50t lighter sister.

The other obvious reason for quads, is the upper limit of engineering capability in producing thrust to get a larger twin.
 
Thorben
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 5:36 pm

Quoting PlaneHunter (Reply 66):
"Things" look particularly a lot different in the respective order books...

Reasons for buying also look different. How often do I have to say it?

Quoting PlaneHunter (Reply 66):
Which ones are you referring to specifically?

A343 and 772. Operated both by AF, CX, KU, EK and CA.

Or the A346 and the 773.

EK, EY, CX and TG.

Quoting PlaneHunter (Reply 66):
And how do you explain that twins outsell quads?

What do you compare there?
777 vs. A340?
777/A330 vs. A340?
737/757/767/777/787/A320/A310/A300/A330 vs. A340/747/A380/BAe146/Il-96??
 
Pihero
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 5:38 pm

Widebodyphotog,
I'm not quite sure whether we agree on the definition of "zero fuel weight ".
Maybe this link will square it for us :
http://www.westwingsinc.com/zero.htm
Now, can you see the contradiction on the two parts of your first paragraph :
1/-

Quoting Widebodyphotog (Reply 74):
Huh? So in other words structural payload capability increases because wing loading and subsequently bending loads increase? But the A340-300 has a lower structural payload limit than the A330-300 and the ZFW relative to structural weight is worse in terms of structural efficiency...The structure of the A340-300 is heavier than the A330-300 because the former requires a heavier structure to carry the higher mass fraction of fuel for longer range included in 100,000lbs of higher takeoff weight

2/-

Quoting Widebodyphotog (Reply 74):
In theory the structure of a wing can be made lighter because the weight of engines placed further out on the wing provide greater bending relief. So in theory a quad's wings would be lighter than a twins...for the same total mass of aircraft...

So which one is right , then?

Quoting Widebodyphotog (Reply 74):
BTW The Tristar was not heavier than the DC-10 because the engines were placed further outboard

Never said that

Quoting Widebodyphotog (Reply 74):
The L-1011 wing had reduced bending loads from the combination of having the engines further outboard and incorporating an active gust alleviation system.

ZFW involves static conditions so the gust alleviation system -which only happened with the Tristar-500 series- has nothing to do with it.
As I said, having engines the farther out on the wing span would allow for either a higher ZFW or a lighter structure. We are not disagreeing, we just are not talking about the same thing.
Zeke sums it up quite nicely :

Quoting Zeke (Reply 78):
The 343 on takeoff is a lot heavier than then 333, the additional mass of fuel in the aircraft has bending moment relief of the outer engines, thus allowing for a lighter wing, sharing 90% structural commonality with the 333 wing



Quoting Widebodyphotog (Reply 75):
But this is a false assumption that four engined aircraft cores are linked to less efficient fans and twins are linked to more efficient fans. Especially when taking into account Three spool engines like the Trent 900 and Trent 500 where spool efficiencies are ostensibly more closely matched. It is not an inherent property of twins to have more efficient fans...I mean the 747 and 767 have the exact-same-engines...

Please re-read the relevant portion of my post .Sorry my english can be as good as yours. In this paragraph, I was talking about operational use / efficiency of the core which peaks in the higher throttle positions, RPMs...

Quoting Widebodyphotog (Reply 75):
GE has a great technical publication on GE90 that goes through a lot of this chapter and verse, I'll try to dig it up, but now we are really getting off topic here...

Please, yes.
 
macc
Topic Author
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 6:11 pm

Quoting MD-90 (Reply 76):
Quoting Macc (Thread starter):
All in all, most of the station managers tried to get the 777 but now are happy to get the 330 due to significant lower "operating" costs. This however is not so much due to the fuel consumption but due to the fact that purchasing / leasing costs are partially included into the calculating.

I figured that would bring the pro-Airbus camp out spoiling for a fight, but it hasn't. Kudos.

Well, it has brought out a bunch of people cock fighting about technical details which are just boring. My post was to show that BOTH products have markets and pro and cons... and airline business is not at all focused on technical datas only. But that seems to have gone under...

Way to few people here who do love airplanes regardless of their manufacturers.
 
Pihero
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 6:46 pm

You are quite right. The second part of this thread should be in Tech?ops.
But you also should have noted yhat basically everybody has agreed with you, which on this forum is no mean feat.
As for boring, you have never seen a group of pilots discussing for hours the best way to stop an airplane to the gate...
 
widebodyphotog
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RE: A Contribution To 330 Vs 777

Fri Apr 07, 2006 9:33 pm

Quoting Pihero (Reply 80):
Now, can you see the contradiction on the two parts of your first paragraph :

It's not a contradiction, I was trying to understand the point you were making by asking a question, stating the fact about the A340-300 airframe structure, pointing out the reason for it's higher ZFW is not because of increased bending relief, but the necessity of supporting an overall higher weight of airplane, then in the following paragraph pointing out that in theory a quad's structural weight should be lower by design.

Quoting Pihero (Reply 80):
As I said, having engines the farther out on the wing span would allow for either a higher ZFW or a lighter structure. We are not disagreeing, we just are not talking about the same thing.
Zeke sums it up quite nicely :

My apologies Pihero, it appears we are. Adding in the aspect of ZFW threw off my perspective a bit it seems. I think in better terms we can describe the advantages of higher ZFW or lower structural weight as better "useful load".

However, the fundamental disagreement with Aviator27 still remains. TSFC is not a function of number of engines. From our back and forth I think we can conclude that from a structural point of view, a quad with wing mounted engines can theoretically have a lighter structure than a twin for a given mass of aircraft, potentially allowing greater range because the mass fraction of fuel at a given payload can be higher. A quad could theoretically have greater useful load than a twin for a given mass because of lower structural requirements. But this does not affect TSFC.

Quoting Zeke (Reply 78):
Yes I agree, the 772 is not best suited for some of the routes its being used for, and the Boeing numbers do not stack up on short sectors. This is something which has been known in industry for some time, however on a.net the opposite is considered true.

The problem is, and is what I was trying to get at in a round about way, is that we can not conclude how the 777-200 performs against the A330 because the 777 data averages results from disparate routes while the A330 information is from similar sector lengths. Fuel burn rates are less for the lighter 777's operated on shorter routes comparable to what the NW and US A330's are doing. The majority of 777 routes may be under 4,000nm but the longer sectors are significant enough in number to bring down the departure frequency average even though the data contains data from short range 777's that are operating with much higher departure frequency than the average would suggest. If the the A330 data was averaged from such diverse lengths of routes the comparison result would be totally different, and the point on top of that is we can never compare the A330 subtypes to the 777-200 subtypes on a fleet basis each having similar composition of routes because the A330 subtypes can not perform the diverse range of missions that the 777-200 subtypes can...

The data would suggest that the 777-200 has a 34% increased CASM over any mission that the A330 can do. That's simply not the case and you know that. If we are not going to analyze 777-200 performance over like missions or across fleets with similar diversity of segments then we do not have a valid comparison.

We do not know from the data summary that the Boeing data does not "stack up" on shorter segments because the data does not show specifics of shorter sectors for 777-200. It's mixed with very short and very long sectors while the A330 data is from sectors of very similar length. If in reality there was such disparity in operating costs, sector for sector, fleet for fleet between A330 and 777-200 Boeing could not sell a single plane...

The reality sector for sector the applicable 777-200 subtype CASM is nearly as good or better than the A330 because the fuel burns are not that different and the 777 has a higer capacity in practice. We can quibble about maintenance costs, financing and the related blah blah blah, but there is not a vast disparity in CASM on comparable applications.

There is no way to pull out the relevant data for a direct comparison 777-200 to A330 from this data. However, the total sales figures may be more reflective of the applicable performance advantages each comparable sub type enjoys IMO.

767-300ER: 513
A300-600: 286

A330-200: 330
767-400: 41

A330-300: 252
777-200A: 88

A340-200: 28
NO DIRECT COMPETITOR

A340-300: 219
777-200ER: 423



-widebodyphotog
 
PlaneHunter
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RE: A Contribution To 330 Vs 777

Sat Apr 08, 2006 5:04 am

Quoting Thorben (Reply 79):
A343 and 772. Operated both by AF, CX, KU, EK and CA.

- AF's A343 were introduced long before the B772ER - and later B777s were added while the A340 fleet was reduced. Expect more A340s to leave with more B777s being added.
- Cathay once decided against ETOPS long range operations, but that policy has ended when they ordered the B77W. Expect the A343 slowly being replaced by a mix of B777s and A330s.
- Kuwait only operates two B772s and four A343, we all know that makes no sense. It's not a representative example.
- And EK simply added the A343 due to a shortage of capacity. Expect the A343 to be replaced by B777s.

Quoting Thorben (Reply 79):
Or the A346 and the 773.

EK, EY, CX and TG.

Don't mix up ER-versions and non-ER-versions. None of the mentioned carriers operates the direct competitors A346 & B77W.

EK has just delayed the A346, CX's leased A346 will leave as soon as B77W arrive and EY adds similar types simply because they need to grow fast. Whether they keep the A346 remains to be seen.

Quoting Thorben (Reply 79):
What do you compare there?
777 vs. A340?
777/A330 vs. A340?
737/757/767/777/787/A320/A310/A300/A330 vs. A340/747/A380/BAe146/Il-96??

I'm not sure what's the purpose of posting all these different aircraft types, but to get back to our subject - why don't you just compare aircraft which are similar in capacity, range & payload? E.g. A343 vs B772ER, A346 vs B77W.


PH
 
khobar
Posts: 1336
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RE: A Contribution To 330 Vs 777

Sat Apr 08, 2006 6:49 am

Quoting Zeke (Reply 39):
Cost per Block hour / Lease rental capital cost per month/Gal of fuel per hour/Seats

I'm curous why the Boeings have increased their fuel burn by 10%+ while the Airbus hasn't.

I'm seeing ICAO figures of 1217, 1297, and 1929 gal/hour for 762, 763, and 772.

And someone asked about the A332 - 1762/hour.

I can only assume that US-based Boeings burn substantially more than average for the types, while US-based A330's burn exactly the same as average for the type, but I have no idea as to why that would be.

(As a sidenote, fuel burn figures for 343 and 346 are 2174 and 2584, resp.)

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