EA772LR
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Fuel Burn Difference Between The A346 And 742/3/4?

Wed Dec 30, 2009 4:27 pm

I was wondering about the fuel burn difference between the A346 and the 742 and 743 since the A346 was intended to replace the classic 747s and even some 744s for some operators. I know a lot of dirt gets thrown around here on the how much less efficient the A346 is than the 77W, but we already know for just about every mission the 77W is the better choice. This has to do with how well the A346 fulfills its role as a 742/743 replacement. IMHO, I think it has/had fulfilled that role.
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jayeshrulz
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RE: Fuel Burn Difference Between The A346 And 742/3/4?

Wed Dec 30, 2009 4:32 pm

IIRC, the A346 was bought in to compete with T7 and 747 not the classics.
Airlines who use A346 fly in hot and high conditions which is more preferable.

And even if its true the A346 was made to replace the classics, what is the point?
Why to compete with a far previous generation aircraft when the company who made it made a new model to overtake it?
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EA772LR
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RE: Fuel Burn Difference Between The A346 And 742/3/4?

Wed Dec 30, 2009 4:48 pm



Quoting Jayeshrulz (Reply 1):
IIRC, the A346 was bought in to compete with T7 and 747 not the classics.
Airlines who use A346 fly in hot and high conditions which is more preferable.

No the A346 was made to replace 742/743 aircraft. When the A346 was developed, the 77W wasn't even on the drawing board yet.
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BlueSky1976
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RE: Fuel Burn Difference Between The A346 And 742/3/4?

Wed Dec 30, 2009 5:09 pm



Quoting EA772LR (Reply 2):
Quoting Jayeshrulz (Reply 1):
IIRC, the A346 was bought in to compete with T7 and 747 not the classics.
Airlines who use A346 fly in hot and high conditions which is more preferable.

No the A346 was made to replace 742/743 aircraft. When the A346 was developed, the 77W wasn't even on the drawing board yet.

Boeing actually advertised the non-ER 777-300 as a successor to "older 747 Classics" (Boeing PR talk for 747-100/-200), however, it was never used on any transoceanic routes. The A340-600 took off and beat 777-300 due to its superior capabilities, which in turn forced Boeing to design the 777-300ER.
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EA772LR
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RE: Fuel Burn Difference Between The A346 And 742/3/4?

Wed Dec 30, 2009 5:30 pm



Quoting BlueSky1976 (Reply 3):
Boeing actually advertised the non-ER 777-300 as a successor to "older 747 Classics" (Boeing PR talk for 747-100/-200)

Right, I never disagreed. And for the operators who use the 773 (non-ER) they work very well as a 741/2/3 replacement.

Quoting BlueSky1976 (Reply 3):
however, it was never used on any transoceanic routes.

KE used their 773s to LAX.

Quoting BlueSky1976 (Reply 3):
The A340-600 took off and beat 777-300 due to its superior capabilities, which in turn forced Boeing to design the 777-300ER.

Only superior at longer ranges. A standard A340-600 weighs almost 150,000lbs more at MTOW than a non-ER 773. I started this thread so that I could better understand how the numbers work regarding fuel burn for an A346 vs. 742/3/4.
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Flighty
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RE: Fuel Burn Difference Between The A346 And 742/3/4?

Wed Dec 30, 2009 7:53 pm

I am away from my files but it's basically that the B744 enjoys a 10 to 12pct advantage in fuel burn over the 747 Classics. Then, the A346 might be 10 pct better than 744. As a result, the A346 did accomplish the mission of fully replacing the 747 in capability, while burning less fuel.
 
trex8
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RE: Fuel Burn Difference Between The A346 And 742/3/4?

Fri Jan 01, 2010 12:01 am

off the top of my head I remember Zeke saying once the 77W burned about 8000lbs/hr fuel (or maybe it was gallons or kgs but whatever the relative differences are the same), the A346 about 8700 and the 744 something over 11000.
 
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747classic
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RE: Fuel Burn Difference Between The A346 And 742/3/4?

Fri Jan 01, 2010 6:03 pm

If you want to compare the fuel consumption of the A346 with the 747 classic, you first have to decide : Against what type of classic I want to calculate the difference in fuelconsumption ?

First generation classics
747-100/200 powered by P&W JT9D-7 engines up to and incl. JT9D-7J.

Second generation classics :
747-100/200/300 powered by P&W JT9D-70 and 7Q series, GE CF6-50 series and RR RB211-524C/D series.

Third generation classics :
747-200/300 powered by P&W JT9D-7R4G/H engines and GE CF6-80C2B1 engines.

The difference of the best (GE CF6-80C2B1) and the worst (P&W JT-9D-7J) is more than 15% fuel consumption.

The CF6-80C2B1 powered 747 classic are only 4 % less fuel efficient than the 747-400's.(FADEC 1%,wing + winglet 3%)
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RE: Fuel Burn Difference Between The A346 And 742/3/4?

Fri Jan 01, 2010 7:40 pm



Quoting EA772LR (Reply 4):

Only superior at longer ranges. A standard A340-600 weighs almost 150,000lbs more at MTOW than a non-ER 773. I started this thread so that I could better understand how the numbers work regarding fuel burn for an A346 vs. 742/3/4.

Yes, but outside of Asia, such large aricraft are not used on short routes. At the time the 741/2 were introduced, they were among the longest-range aircraft of their time. By the time the 773 came around, the 767 and A330 were available for tranatlantic service and the trend was for smaller aircraft on such routes. The 742's were still being used, of course, because the airlines had them, but there wasn't much interest in a direct replacement. The 744 replaced the 742, and that is hardly a direct replacement. While some airlines did use 744's on these routes, the 744 had such a broad range of possible applications that adding a separate flee type just for those routes made no sense, even if the economics were superior to the 744. This basically reduced the 773 to a niche aircraft that works great in heavily regulated/slot-restricted markets, but nowhere else.

The 77W has the range, capacity, and far superior fuel burn to the 346. With the exception of some niche applications (hot and high, trans-Antarctic) the 77W is unquestionably the superior aircraft.

Quoting 747classic (Reply 7):

The CF6-80C2B1 powered 747 classic are only 4 % less fuel efficient than the 747-400's.(FADEC 1%,wing + winglet 3%)

But doesn't the 744 have more thrust for the same fuel consumption?
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747classic
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RE: Fuel Burn Difference Between The A346 And 742/3/4?

Fri Jan 01, 2010 8:53 pm



Quoting DocLightning (Reply 8):
But doesn't the 744 have more thrust for the same fuel consumption?

The CF6-80C2B1F as installed on the 744 has slightly more T/O thrust (higher rating), because of the higher MTOW of the 744,compared to the 742/3. The T/O thrust-weight ratio of the 747-2/3 is however better, the climb out ( MCT) performance at MTOW of the 742/3 is far better, because of the approx. same CLB thrust levels of both engines, despite the wing extension and winglets on the 744.
The basic engine is exactly the same for both, except for the FADEC on the 744 and the mechanical engine fuel control, with digital supervisory (PMC = power management control) on the 742/3.
The SFC (cruise) difference is approx. 1% between the -B1 and B1F variant.

CF6-80C2B1 , T/O thrust 55.980 lbs, Max. Continuous Thrust 49.550 lbs

CF6-80C2B1F, T/O thrust 57.160 lbs, Max. Continuous Thrust 49.810 lbs

For further info : Type certificate E13NE (GE CF6-80C2 engine)

744 MTOW = 875.000 lbs.
742/3 MTOW = 833.000 lbs.
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DocLightning
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RE: Fuel Burn Difference Between The A346 And 742/3/4?

Fri Jan 01, 2010 9:16 pm



Quoting 747classic (Reply 9):

The CF6-80C2B1F as installed on the 744 has slightly more T/O thrust (higher rating), because of the higher MTOW of the 744,compared to the 742/3. The T/O thrust-weight ratio of the 747-2/3 is however better, the climb out ( MCT) performance at MTOW of the 742/3 is far better, because of the approx. same CLB thrust levels of both engines, despite the wing extension and winglets on the 744.

Is that higher MTOW the reason that the 744 had such a vastly longer range than the 742?
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mandala499
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RE: Fuel Burn Difference Between The A346 And 742/3/4?

Fri Jan 01, 2010 11:37 pm



Quoting DocLightning (Reply 8):
Yes, but outside of Asia, such large aricraft are not used on short routes.

.............

This basically reduced the 773 to a niche aircraft that works great in heavily regulated/slot-restricted markets, but nowhere else.

I think only Asian carriers got the 773(non-ER)?
It was a nice 741/2/3 replacement for anything up to a 10hr flight. The reason why it worked for Asia is because of the heavily regulated past, making the market adapting to large aircraft for relatively few frequency... but then, when you compare population bases between the points served... it does skew the basic perception a bit.

I can't say much for the non-SE Asia based markets... but... take Jakarta-Singapore for example. SQ operated 773s and 744s on the routes, they could have operated the 772s for more frequencies but decided not to. Then we had SIN-SYD, operated with 3x daily 773/744 mix... Turning it into a 5x daily 767/332 ops might not work.

However, as SE Asia is now slowly liberalizing, with unlimited 3rd/4th freedom rights within capital cities, the days of "widebodies for short routes" may be numbered, unless one can justify the 5 - 8x daily widebody service... even then, it's still ripe for being attacked with 5 - 8x daily with a narrowbody (something Air Asia is doing at the moment on the CGK-SIN route).

Quoting DocLightning (Reply 10):
Is that higher MTOW the reason that the 744 had such a vastly longer range than the 742?

Well, to put it simply... yes... for an X% of OEW increase with a Y% in MZFW increase and Z% in MTOW increase... with physically almost the same engines (just different control methods)... as long as Z is bigger than either X or Y, the answer to your question is... YES.

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Rj111
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RE: Fuel Burn Difference Between The A346 And 742/3/4?

Sat Jan 02, 2010 5:27 pm

The area that the A346 (as well as the 77W) blitzes all of these aircraft - including the 744, is the cargo hold.

It's a decent plane really but it comes up against an exceptional one (the 77W, which is the comfortably the best 777 variant).

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