Despite weak sales, Boeing is still working on performance improvements for the 748i. It may not mean a ton more sales, but since the improvements can be retrofit, it should make current buyers happier with their decision.


http://atwonline.com/airframes/boein...st-flight-performance-improvements

Quote: Boeing said the improvements have resulted in an accumulated 1.5% gain in fuel efficiency since the first aircraft was delivered less than two years ago. “These new improvements will give operators an airplane that is an additional 1.8% more efficient,”

Would that give it another 100-200nm of range?

Calling those efforts "improvement" is probably spinning things a bit too far. In actual fact they are still falling short of the originally projected performance figures, and have some way to go to reach that goal. Only once you go beyond that point can you talk about offering "improvements" to the product.

Don't think this will sway any potential customer, but will of course be beneficial to the current operators - however few and far between they may be.

Quoting B777LRF (Reply 2):

Even if they are falling short on original figures, this is still an improvement.

Quoting virginblue4 (Reply 3): Even if they are falling short on original figures, this is still an improvement.

Well, yes, I suppose it is. But that's not the way the story is spun; unless you know the underlying story, you could well be inclined to believe Boeing are offering something that's better than the original promises.

Quoting B777LRF (Reply 2): In actual fact they are still falling short of the originally projected performance figures, and have some way to go to reach that goal.

With the improvements currently being tested they will at least meet the original performance figures.

From the article:
"The planes delivered so far have been performing very well in service, about 1 percent better than we thought," said Boeing spokesman Jim Proulx.

"They are giving double-digit gains in fuel burn (compared with the models they replace) and are on a path to getting back to catalogue commitments in 2014."
http://www.reuters.com/article/2012/...oeing-weight-idUSL2E8DSG7020120228

tortugamon

Quoting B777LRF (Reply 4):

ATWONLINE isn't casual reading. I venture that most reading it have a good idea what's going on.

Quoting tortugamon (Reply 5): With the improvements currently being tested they will at least meet the original performance figures.

This directly contradicts that assumption:

Quoting tortugamon (Reply 5): "They are giving double-digit gains in fuel burn (compared with the models they replace) and are on a path to getting back to catalogue commitments in 2014."

Being "on a path" very clearly means still not being there, but at least moving towards the goal.

Quoting tortugamon (Reply 5): From the article: "The planes delivered so far have been performing very well in service, about 1 percent better than we thought," said Boeing spokesman Jim Proulx.

And this just means that they're progressing better than they had thought at some unspecified interim point in time, nothing more.

If they were actually about to meet or even exceed the catalog specs, the wording would be entirely different.

Quoting Klaus (Reply 7): This directly contradicts that assumption:

There is nothing contradictory about it. They are currently testing at least three items (engine PIP, FMC & software, aft fuel tank) that will be introduced in 2014 and Boeing is expecting that these improvements will result in meeting the original performance spec.

"The engine PIP alone should bring performance to within 1 percent of specification, while aerodynamic upgrades and weight reductions account for much of the balance."
http://www.ainonline.com/aviation-ne...ntinues-bolster-747-8s-performance

The engine PIP will be on production aircraft by Q4 this year and I believe they are referring to the aft fuel tank allowing for better aircraft trim during flight as 'aerodynamic upgrades' which will be ready for the Intercontinental by early 2014 per BA and LH.

If you have any source that indicates that they will not be meeting spec in 2014 then I would surely like to become better informed.

Quoting Klaus (Reply 7): If they were actually about to meet or even exceed the catalog specs, the wording would be entirely different.

Maybe it would sound like: "Boeing says 747-8 to meet performance spec by 2014" ? Isn't that is the title of the article?

tortugamon

One of the "catalogue commitments" may be the additional required navigation performance features and a “quiet climb” function that will be introduced with version 3.0 of the flight management computer (FMC) software so we perhaps should not assume that such commitments only relate to fuel burn or payload-range.

Quoting tortugamon (Reply 8): Maybe it would sound like: "Boeing says 747-8 to meet performance spec by 2014" ? Isn't that is the title of the article?

The article itself sounds a lot less definitive. That's my point.

Of course it's to be hoped that the improvement programs work out as desired, but from the sound of it they'll know for sure only some way further down the road.

Quoting Stitch (Reply 9): "catalogue commitments

This has been quite a moving target. I wonder which one they are referring to.

The 8i flew right over my head yesterday! Wow! This airplane is absolutely beautiful!

Quoting Stitch (Reply 9):

It should be pointed out that Stitch said, "MAY", as in, "it's a possibility". He didn't say the features mentioned would definitely be part of the package.

That being said, this article mentions the test mule 748i, (formerly intended for LH), and testing the 'quiet climb' feature as well as modifications to the flight management computer and rear tank.

http://www.aviationweek.com/Article....l/avd_12_21_2012_p03-01-531189.xml

Everything he mentioned is in the public domain.

Well, Boeing certainly needs to make "improvements" to meet or exceed their original performance guarantees of 747-8.

I, for one, am glad the hunchback is dying its slow and painful death. It's about time.

Bring on the Mighty Triple Seven Dash Nine!

Quoting BlueSky1976 (Reply 15):

A little more respect for an aircraft with such a resume (B747).

Quoting boeingguy26 (Reply 17): A little more respect for an aircraft with such a resume (B747).

No way. Sorry.

Quoting tortugamon (Reply 8): I believe they are referring to the aft fuel tank allowing for better aircraft trim during flight as 'aerodynamic upgrades'

The tail tank isn't used for trim, only to carry more fuel. It gets emptied once there's room in the centre tank. There's no way this could be considered an aerodynamic improvement.

Quoting dynamicsguy (Reply 19): The tail tank isn't used for trim, only to carry more fuel.

"Re-activation of the tail fuel tank will provide added range and improve the aircraft’s performance, says Lufthansa’s Boje. The extra weight of the fuel in the aft of the aircraft can be used to assist in trimming the 747-8 to lower cruise drag. The 747-8’s fuselage extension “tends to be nose heavy so we might gain performance,” he adds."
http://www.aviationweek.com/Article....d_12_21_2012_p03-01-531189.xml&p=1

tortugamon

I kinda think that more use of composites durin design would lead to double digit fuel improvement. Me thinks that Boeing didn't do that and went a cheaper way because it doesn't believe in very large aircraft. The 777-9 is significantly better than 747-8

Quoting cobra27 (Reply 20): The 777-9 is significantly better than 747-8

Its possible that it will be. But I would be very careful to say anything that doesn't yet exist is better than something that actually is flying around.... lol... I mean, really....

...My fantasy of time travel is better than the 777-9  

-AA777

This shows the story may not be quite over yet. If Boeing can show they are on a path to meeting the spec targets... and maybe even move beyond them... airlines could be willing to take another look at the aircraft. However, I think the price rather than the performance specs is the issue. In my opinion the 748i is overpriced for what it is. If they can somehow meet listed specs and get that price down... then maybe they have a winner.

Quoting cobra27 (Reply 19): The 777-9 is significantly better than 747-8

Oh yes, and where may I see it flying? On a piece of paper or a computer screen?

Quoting tortugamon (Reply 8): If you have any source that indicates that they will not be meeting spec in 2014 then I would surely like to become better informed.

I recall Elizabeth Lund saying that the 748 eventually will come 'very close' to the original specification but weight will remain an issue.

Why would Boeing continue to invest in an aircraft with so few orders/potential customers?

re reply 14

"Well, Boeing certainly needs to make "improvements" to meet or exceed their original performance guarantees"

Since they are not selling any at the mo' this is the reason - the birds they 'have' sold are costing them money - and this is on top of a loss making programme.

Having said that if the 748 can be improved then they will hopefully sell more cargo planes as the economy improves.

But as stated in this thread. Regarding PAX Boeing have moved on to the 779 now. Instead of getting towards double digit (9%?) improvements (against a 744) the 779 will slaughter the (744) figures! 20%? Yup I believe so.

Quoting KarelXWB (Reply 23): I recall Elizabeth Lund saying that the 748 eventually will come 'very close' to the original specification but weight will remain an issue.

747classic noted in Randy T Says 748-F Better Than Expected (by ER757 Apr 4 2012 in Civil Aviation) that the initial 747-8F deliveries were between 4,000 and 6,000 pounds above spec weight. Boeing subsequently raised the MTOW of the 747-8F by six tons ("IN FOCUS: Rating the Prospects of the 747-8 Freighter" by Peter Conway on 31 May 2012) for post-April 2012 deliveries to compensate for this.

In his "IN FOCUS: Boeing 747-8 Technical Description & Cutaway" article from 13 November 2012, Max Kingsley-Jones noted Boeing had planned to remove 2.27 tons (5,000 pounds) of weight from the 747-8.

On 5 December 2012, Steven Trimble reported in "Boeing Reduces 747-8 Weight, Tweaks Aileron Setting" that Boeing had removed 5500 pounds / 2500kg of weight from late 2012 747-8 Freighter deliveries compared to late 2011 747-8 Freighter deliveries so it sounds like Boeing has mostly, if not completely, taken care of the OEW overage on the freighters, at least.

[Edited 2013-05-22 11:06:23]

@Stitch That's why Lund said "very close".

[Edited 2013-05-22 11:41:00]

Hey stitch am confused now.

Does you mean that even with current improvements the weight is still over planed initially?

Quoting cobra27 (Reply 28): Does you mean that even with current improvements the weight is still over planed initially?

I am guessing that if it is, it's in the range of hundreds of kilograms (at least for current deliveries of the freighter model), but I do not have a definitive number.

If I may explain why an aft fuel tank can help with 'aerodynamics' for those of us who may not be so familiar with W/B concepts.

As we all know, the wing creates lift in an upward direction, perpendicular to the relative wind. Lift creation causes induced drag as a byproduct.

An airplane has to achieve balance, and in 'stable' commercial aircraft, where the center of gravity (CG) is designed to fall ahead of the center of lift (nose heavy in simple terms), a balancing force should act behind the wing to keep the aircraft pointing straight. That force is provided by the horizontal stabilizer (horizontal tail).

The more nose heavy an aircraft becomes, the more downward lift it will require from the tail. More downward lift from the tail will result in both an increased induced drag from the tail, and more weight to be carried (offset) by the wing again creating more induced drag from the wing.

By moving more fuel to the tail, the CG will get closer to the center of lift, therefore relieving the horizontal stabilizer from having to GENERATE downward lift (because the transferred weight is doing its job.) resulting in reduced induced lift.

I hope this helps those enthusiasts without an aero background.

To understand the above mentioned SFC and OEW figures better, here is some History of the 747-8 program (see also my posting of April 5 2012 as quoted by Stitch.) :

- Early in the 747-8 program an usual issue was noticed : Operating Empty Weight (OEW) was above design target. The exact amount is stil a well kept secret, but somewhere between 4000 and 6000 lbs in the early built airframes will be a good guess. This figure was also in line with the later published plans of Boeing to remove at least 5000lbs of the OEW gradually in later produced airframes.

- On top of that a more serious problem emerged : the TSFC of the GEnx-2B67 engine was 2.7% above specification.

- Consequently the aircraft was below the payload range performance, promised by Boeing to the airlines.

- To restore the payload range of the aircraft, the maximum operating weights were increased, after evaluation of the actual flight loads during the test flights showed that it was possible to increase these maximum structural weights, without structural reinforcement. The Max Zero Fuel Weight (MZFW) was increased to keep the maximum design payload the same. The Maximum T/O Weight (MTOW) was increased from the design 970.000 lbs to 987.000lbs. The increase of 17.000 lbs was used to restore the max. range at max payload by allowing an increase in fuel qty ( 11.000-13000 lbs) at MTOW. (The 747-8F is not fuel limited at MTOW with max payload) .

- After evaluation of the actual fuel consumption during the first months of airline operation, Boeing (the messenger : Randy Tinseth) has stated in Randy's Journal that the actual performance is 1% better than the zero reference. This was very good news, aerodynamically the aircraft must have been better than expected (lower drag).

The result was from the start (EIS) an aircraft with an exactly or even better payload-range than designed.
However the promised fuel consumption target was not met, due heavier aircraft weights (0.5-1.0%) and under performing engines(-2.7%).

The exact performance of this IGW-aircraft was now calculated and measured during the final stages of the flight test program and used as a zero reference for the FMC data base and performance calculations used for flight planning.

Seen the improvements of the GEnx-2B PIP engine (with aircraft/engine certification scheduled before the end of 2013) with a TSFC improvement of 1.8% and the OEW overweight reduced to a few hundred pounds, this will produce an aircraft exactly (or even slightly better) than the design fuel consumption target, but with a much better than expected payload-range performance due the higher than original designed maximum operating weights of the aircraft.

747-8 Aircraft status at the end of 2013.

- OEW on spec or a few hundred pounds above target : SFC = 0,1 % above target

- GEnx-2B/P1 engine .....................................................: TSFC = 0,9 % (2,7 % - 1,8%) above target

- Aerodynamic airframe performance ...........................: SFC = - 1,0 % below target

Conclusion :

- The aircraft/engine combination is exactly on target, but the engines are still 0,9 % above TSFC target.
- Payload-range is better than original spec, due increased operating weights.

[Edited 2013-05-22 14:03:07]

Quoting 747classic (Reply 31):

I find this confusing;

Quote: Boeing said the improvements have resulted in an accumulated 1.5% gain in fuel efficiency since the first aircraft was delivered less than two years ago. “These new improvements will give operators an airplane that is an additional 1.8% more efficient,”

To me, the most likely interpretation is that up to now, Boeing has improved the fuel burn by 1.5%...before the latest improvement, which will add another 1.8%.

The wording of the story is a bit clumsy...so it's not entirely clear if the two are additive or the total gain in efficiency is 1.8%.

I wish this were true http://fbcdn-sphotos-e-a.akamaihd.ne...0023_4238322135088_836466739_n.jpg

Quoting 747classic (Reply 31): To understand the above mentioned SFC and OEW figures better, here is some History of the 747-8 program (see also my posting of April 5 2012 as quoted by Stitch.) :

Thanks 747classic, and great post   

Quoting JoeCanuck (Reply 32): To me, the most likely interpretation is that up to now, Boeing has improved the fuel burn by 1.5%...before the latest improvement, which will add another 1.8%. The wording of the story is a bit clumsy...so it's not entirely clear if the two are additive or the total gain in efficiency is 1.8%.

I would say the previous 1.5% is coming from the weight reductions.

There were also other improvements over the time, the first 747-8i for LH was equipment with FMC 2.0 while the first freighters had an older version of the software.

Quoting JoeCanuck (Reply 6): ATWONLINE isn't casual reading. I venture that most reading it have a good idea what's going on.

Doesn't seem to be that easy:

Quoting JoeCanuck (Reply 32): The wording of the story is a bit clumsy...so it's not entirely clear if the two are additive or the total gain in efficiency is 1.8%.

Quoting kilauea717 (Reply 24): Why would Boeing continue to invest in an aircraft with so few orders/potential customers?

Maybe they have a reason to keep the promises they have made to LH?

Quoting Unflug (Reply 35): Maybe they have a reason to keep the promises they have made to LH?

Not just LH but all customers for all products. Customers have to have faith that Boeing or Airbus will live up to their promises or at least their absolute best to get their. Besides, selling one additional jet should pay for much of this additional costs of improvement. The more 748s that are out in the market the cheaper additional aircraft become for everyone involved.

Quoting JoeCanuck (Reply 32): To me, the most likely interpretation is that up to now, Boeing has improved the fuel burn by 1.5%...before the latest improvement, which will add another 1.8%.

I think Karel is right about the 1.5%. The 1.8% is due to the engine PiP I believe. I agree that it was not worded well.

tortugamon

The 1.5 %, mentioned by Boeing is probably the operational empty weight reduction from the start of the production up to now.
Included in this figure are also minor aerodynamic tweaks with as most important tweak the introduction of slightly drooped outboard ailerons (offset neutral position) during cruise, possible by the new FBW roll system ( by software update) and introduced from the start at the 747-8I, but also implemented at the freighter and as a retrofit to early airframes.

[Edited 2013-05-23 03:24:52]

all I can say is...................... it is way too late, very late, extremely late already in the market.

Quoting 747classic (Reply 31): OEW on spec or a few hundred pounds above target

Does this mean that the Dec 2012 ACAP sheet OEW of 220.128t for the -8i will be achieved by the end of 2013 or will it still be a little higher.?