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787 Electric Architecture Due Wings Too Thin  
User currently offlinetrex8 From United States of America, joined Nov 2002, 4497 posts, RR: 14
Posted (9 months 3 weeks 4 days 21 hours ago) and read 6066 times:
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I can't find this on the Flightglobal website but in the print June 25-Jul 1 edition on page 11 in an article "Boeing locks down 777X performance, strategy" they quote Mike Blair VP marketing commenting on the de icing system on the 777X
"Although the 787's electric architecture is billed as a fuel saving innovation, Blair says, the actual reason it was selected was because the composite wing was too thin to accommodate a pneumatic system"
they go on to say the 777X wing doesn't have this problem so it will be pneumatic

A year or two before the 787 first flight there was a FG article also quoting a 787 electrical systems supplier that they saw no or very little likely fuel saving advantage to the all electric system. I could see a maintenance advantage though same article also said the same supplier said the electrical systems are so much higher in capacity that may not be true either.

So more PR hype by the marketing boys?

25 replies: All unread, showing first 25:
 
User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 1, posted (9 months 3 weeks 4 days 20 hours ago) and read 6016 times:

If the 787 wing is too thin for hot air deicing, how can an MD-80 or 737 have it?

Quoting trex8 (Thread starter):
A year or two before the 787 first flight there was a FG article also quoting a 787 electrical systems supplier that they saw no or very little likely fuel saving advantage to the all electric system.

Even if this is so, removing the bleeds entirely means a big decrease in complexity for the engines, meaning as you say less maintenance, but also less design and construction cost.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offline7BOEING7 From United States of America, joined Oct 2012, 1321 posts, RR: 8
Reply 2, posted (9 months 3 weeks 4 days 19 hours ago) and read 5997 times:

It's one thing to use electric deicing on the wing but the size and complexity of the electrical system is way beyond what would be required for just that.

User currently offlineDocLightning From United States of America, joined Nov 2005, 18712 posts, RR: 58
Reply 3, posted (9 months 3 weeks 4 days 18 hours ago) and read 5924 times:

I read an interview with Mr. Leahy where he said that he had discussed going all-electric on the A350 with his engineers and was talked out of it after they told him that, yes, it would be slightly more efficient, but a lot more expensive to design and that he would be unhappy with the reliability of such a system.

Sure enough, the 787's all-electric architecture is having some reliability issues.

Nothing that won't be worked out in the long run, of course. But it's been an unusually trying "teething period."


User currently offlinebikerthai From United States of America, joined Apr 2010, 2013 posts, RR: 4
Reply 4, posted (9 months 3 weeks 4 days 10 hours ago) and read 5709 times:

Quoting trex8 (Thread starter):
a 787 electrical systems supplier that they saw no or very little likely fuel saving advantage to the all electric system.

Are they talking about fuel savings from a pure energy input/output stand point or did they consider the also the fuel impact of the weight of an electrical vs a pneumatic system?

Quoting Starlionblue (Reply 1):
If the 787 wing is too thin for hot air deicing, how can an MD-80 or 737 have it?

Perhaps not too thin but too flexible. Imagine the number of flex joint you will need to duct a titanium tube up the wing.

Aren't the 787 leading edge a composite part with an aluminum wear strip? If so, then you are not going to blow hot air on to that leading edge for anti-ice. If that leading edge is all aluminum, then ignore that last comment . . . but the flexing of the wing would still be true.

bt



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlinePITingres From United States of America, joined Dec 2007, 1089 posts, RR: 13
Reply 5, posted (9 months 3 weeks 4 days 9 hours ago) and read 5659 times:

I'm more inclined to think that the BS part is "the 777X wing doesn't have this problem so it will be pneumatic". If the 777X keeps its existing pneumatic bleed system, surely it's more to reduce the amount of redesign needed and maintain commonality with the existing systems architecture, than because of any dimensional properties of the new wing.

Revising the 777X into a no-bleed architecture would be a massive job, I would have to think beyond what one would want to do with a derivative.



Fly, you fools! Fly!
User currently offlinebikerthai From United States of America, joined Apr 2010, 2013 posts, RR: 4
Reply 6, posted (9 months 3 weeks 4 days 5 hours ago) and read 5499 times:

Quoting PITingres (Reply 5):

Revising the 777X into a no-bleed architecture would be a massive job

And would require engine manufacturers cooperation.  

bt



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlineairmagnac From Germany, joined Apr 2012, 276 posts, RR: 43
Reply 7, posted (9 months 3 weeks 4 days 3 hours ago) and read 5409 times:

Quoting trex8 (Thread starter):
So more PR hype by the marketing boys?

I'd say it's somewhat the opposite, they're playing down the all-electric hype. Boeing PR touted the all-electric architecture as the best invention since sliced bread, so one would expect any future B product to be as electric as possible.

But today, generally speaking, reality is that power electric systems are bigger and heavier, imply a different management of thermal loads, new constraints on systems installation and still require relatively high maintenance. The benefits exist for sure, but they are far from being as clear cut as the 787 marketing claimed.

As said in previous posts, it makes perfect technical sense to be conservative on the 777X, but it kind of goes against the earlier claims of the marketing department. So it seems to me they're a little       :
"Well, ya know, it's really great, it really really is, but, well, ya know, maybe not as much as we said....But it's still great, I swear !"  



One "oh shit" can erase a thousand "attaboys".
User currently offlinetrex8 From United States of America, joined Nov 2002, 4497 posts, RR: 14
Reply 8, posted (9 months 3 weeks 4 days 3 hours ago) and read 5406 times:
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Quoting Starlionblue (Reply 1):
If the 787 wing is too thin for hot air deicing, how can an MD-80 or 737 have it?

As a non technical type I was hoping technical types like yourself could enlighten me!

Quoting bikerthai (Reply 4):
Are they talking about fuel savings from a pure energy input/output stand point or did they consider the also the fuel impact of the weight of an electrical vs a pneumatic system?

It seems to me that when the 787 was developed B said that there would be a 20% fuel savings over the 767 and then various people in the media made much of it being of composite manufacture and the bleedless systems. As we now know, most if not 3/4 of that savings is from the engines, the rest probably split pretty equally between better aerodynamics, lighter weight from composites and some magical improvement due to bleedless equipment so I think they are talking about overall fuel use.

Quoting bikerthai (Reply 4):
Perhaps not too thin but too flexible.

that seems to make a lot of sense


User currently offlinehivue From United States of America, joined Feb 2013, 928 posts, RR: 0
Reply 9, posted (9 months 3 weeks 4 days 3 hours ago) and read 5393 times:

Quoting bikerthai (Reply 4):
Perhaps not too thin but too flexible.

The 777X wing will have a lot of flex too, right?

Quoting PITingres (Reply 5):
Revising the 777X into a no-bleed architecture would be a massive job

Which I suspect is the real reason Boeing is going with pneumatic wing deicing on the 777X (and no electric brakes, too). They're going to have bleed air anyway, so why not use it?


User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 10, posted (9 months 3 weeks 3 days 22 hours ago) and read 5239 times:

Quoting hivue (Reply 9):
Quoting PITingres (Reply 5):
Revising the 777X into a no-bleed architecture would be a massive job

Which I suspect is the real reason Boeing is going with pneumatic wing deicing on the 777X (and no electric brakes, too). They're going to have bleed air anyway, so why not use it?

Agreed. Why reinvent the wheel? Same deal as with the 747-8. Evolution not revolution.

Quoting trex8 (Reply 8):
Quoting Starlionblue (Reply 1):
If the 787 wing is too thin for hot air deicing, how can an MD-80 or 737 have it?

As a non technical type I was hoping technical types like yourself could enlighten me!

For the record, I'm not a technical type. I went from enthusiast to pilot, and so far only pilot of small planes sans fancy stuff like leading edge heating or, heck, air conditioning. I just know how to break the things. 



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinecornutt From United States of America, joined Jan 2013, 338 posts, RR: 1
Reply 11, posted (9 months 3 weeks 3 days 21 hours ago) and read 5209 times:

Quoting bikerthai (Reply 4):
Perhaps not too thin but too flexible. Imagine the number of flex joint you will need to duct a titanium tube up the wing.

Hmm... makes me wonder how Boeing was planning to handle this back when they were thinking about the folding wing ends for the 777.


User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 12, posted (9 months 3 weeks 3 days 14 hours ago) and read 5082 times:

Quoting cornutt (Reply 11):
Quoting bikerthai (Reply 4):
Perhaps not too thin but too flexible. Imagine the number of flex joint you will need to duct a titanium tube up the wing.

Hmm... makes me wonder how Boeing was planning to handle this back when they were thinking about the folding wing ends for the 777.

Not saying the folding wings would have been a trivial design challenge but designing an opening rigid conduit does not present the same issues as designing a flexible conduit.

[Edited 2013-07-04 02:34:17]


"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineCALTECH From Poland, joined May 2007, 2013 posts, RR: 27
Reply 13, posted (9 months 3 weeks 3 days 7 hours ago) and read 4931 times:

No Bleed Air = Fuel Savings. Whether it will save money in the long run with this electrical anti-ice protection for the leading edge shall have to wait to be seen. It is different. There is Bleed Air for anti-icing protection on the 787 however, just not as extensive as it's predecessors.

Quoting bikerthai (Reply 4):
Perhaps not too thin but too flexible. Imagine the number of flex joint you will need to duct a titanium tube up the wing.

It has already been done since the 707 days with Boeing. Flexibility of the wing has nothing to do with the type of anti-icing system on the 787 wing.



UNITED We Stand
User currently offlinebikerthai From United States of America, joined Apr 2010, 2013 posts, RR: 4
Reply 14, posted (9 months 3 weeks 2 days 10 hours ago) and read 4594 times:

Quoting hivue (Reply 9):
The 777X wing will have a lot of flex too, right?

As noted in artist sketches. We will have to see when the plane actually takes off.

The wing flex would be a design challenge, but do-able.

My real question is:

Will the new 777 engine use the same core/similar core as the old 777 engines or will they use the 787 or similar core.

How hard it would be to take the old 777 core and make it "bleedless similar to the 787". I put bleedless in quotes as we all know that it's not completely bleedless.

bt



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently onlineStitch From United States of America, joined Jul 2005, 29700 posts, RR: 84
Reply 15, posted (9 months 3 weeks 1 day 22 hours ago) and read 4425 times:
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Quoting bikerthai (Reply 14):
Will the new 777 engine use the same core/similar core as the old 777 engines or will they use the 787 or similar core.

Looks like it's a new core based on what's been reported, as using a scaled GEnx core would only get them half of the SFC reduction Boeing wants.

The GE9X's HPC will have 11 stages compared to the 10 on GE90 as well as new powdered metal alloys to increase the pressure ratio from 19:1 to 27:1. The total pressure ratio will be 60:1 vs. 50:1 on the GEnx and 40:1 on the GE90.


User currently offlineA380900 From France, joined Dec 2003, 1091 posts, RR: 1
Reply 16, posted (9 months 3 weeks 1 day 10 hours ago) and read 4237 times:

Quoting trex8 (Thread starter):
"Although the 787's electric architecture is billed as a fuel saving innovation, Blair says, the actual reason it was selected was because the composite wing was too thin to accommodate a pneumatic system"

So this feels like "mystery solved" to me. That must explain why the A350 wings look so similar to previous airliners in shape and flex whereas the 787 wings look like a new generation of airplane. We see that the 777X will not use that.

Quoting hivue (Reply 9):
They're going to have bleed air anyway, so why not use it?

I thought the 787 had some bleed, for deicing the engine nacelles or something. No?


User currently offline7BOEING7 From United States of America, joined Oct 2012, 1321 posts, RR: 8
Reply 17, posted (9 months 3 weeks 1 day 7 hours ago) and read 4167 times:

Quoting A380900 (Reply 16):
I thought the 787 had some bleed, for deicing the engine nacelles or something. No?

It does.


User currently offlineferpe From France, joined Nov 2010, 2792 posts, RR: 59
Reply 18, posted (9 months 3 weeks 19 hours ago) and read 4056 times:

Quoting hivue (Reply 9):
They're going to have bleed air anyway, so why not use it?

The GE-9X is as clean sheet as can be (check the GE-9X thread where a guy in the know makes that clear, jetlife2) so that has no influence on the choice of deice. GE could have done little aircraft bleed (GEnx-1B where only the engine inlet is deiced with bleed) or big bleed like the 777. The deciding factor was probably whether they wanted to grandfather the electrical architecture from the 777 or from the 787 and this has normally certification considerations behind it but also fuselage design considerations. If you go to more electrical you need more avionics equipment bay space, more cable conduit space and so on. It essentially means a totally redesigned fuselage on top of a new wing, then you might as well go clean-sheet altogether.

The more electrical architecture was discussed at length (and depth) in the early parts of the A350 prototypes thread, CM (who was part of the 787 project) then clearly stated it saves fuel and maintenance (in the end when mature) but it is not better in weight until the power conversion stuff can be made with air cooling of the semiconductors. Right now it is liquid cooling (like the IBM mainframes CPUs) and that is heavy and a bit complicated as you need an extra cooling system in the frame just for the (famous  ) power conversion racks.

There was also a long and deep discussion on the power conversion efficiency of pressure to work (ie bleed) or electrical to work, the electrical to work proponents seemed to have better arguments. If B goes less electrical next time when they do clean-sheet then we know there is something we don't know about the 787 architecture  .



Non French in France
User currently offlineJoeCanuck From Canada, joined Dec 2005, 5322 posts, RR: 30
Reply 19, posted (9 months 3 weeks 1 hour ago) and read 3863 times:

The bleed architecture of the 777x has everything to do with getting as much of the new plane grandfathered in on the 777 approvals, as well as to keep r&d costs down, and nothing to do with wing thickness.

Bleed is a significant system in aircraft that use it and takes a lot to get certified. To lose the certifications for, and have to re-cert, all of the pressurization, heating, cooling, anti-ice, engine start and numerous other vital systems, really would make the 777x an all new plane.

The flexibility of the anti ice tubes is the least of the problems, and has never been much of an issue. Just look at the flex of a B-52 wing.



What the...?
User currently offlinelightsaber From United States of America, joined Jan 2005, 12444 posts, RR: 100
Reply 20, posted (9 months 2 weeks 6 days 20 hours ago) and read 3803 times:
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Quoting DocLightning (Reply 3):
Sure enough, the 787's all-electric architecture is having some reliability issues.

Really? Pneumatic system are notorious for taking more maintenance time than electrical (or even hydraulic). Did they screw up on the heating pads and having them burn out?

Any my job is now to design pneumatic components. So while I would *love* what you said to be true (job security), it is the opposite of my engineering experience on other projects though...

Quoting JoeCanuck (Reply 19):
Bleed is a significant system in aircraft that use it and takes a lot to get certified. To lose the certifications for, and have to re-cert, all of the pressurization, heating, cooling, anti-ice, engine start and numerous other vital systems, really would make the 777x an all new plane.

Your correct in the extensiveness of bleed air certification. Quite a bit of work is done to verify not only adequate heating, but durability of the system to thermal shock. And then you have to add an engine with all of its "adventure" into the game.

Quoting JoeCanuck (Reply 19):
The flexibility of the anti ice tubes is the least of the problems, and has never been much of an issue. Just look at the flex of a B-52 wing.

Not the frame I was thinking, but there have been some highly flexible wings with conventional anti-icing.

Quoting Stitch (Reply 15):
Looks like it's a new core based on what's been reported, as using a scaled GEnx core would only get them half of the SFC reduction Boeing wants.

It will have to be a new core for the CMC turbine blades and the new compressor blade designs. That would be giving up too much of the fuel burn improvement (as you noted).

Quoting bikerthai (Reply 14):
How hard it would be to take the old 777 core and make it "bleedless similar to the 787".

Not hard, but what's the point? The GE-90 core is now out of date...

Lightsaber



I've posted how many times?!?
User currently offlineJHwk From United States of America, joined Jan 2013, 183 posts, RR: 0
Reply 21, posted (9 months 2 weeks 3 days 7 hours ago) and read 3388 times:

Quoting lightsaber (Reply 20):
Really? Pneumatic system are notorious for taking more maintenance time than electrical (or even hydraulic). Did they screw up on the heating pads and having them burn out?

Electric systems throughout the ages have taken a long time to make reliable. You might be able to take advantage of 99% of lessons learned from marine and stationary applications, but that still only covers about 60% of the design issues.

The electrical power system for a data center has ~99.999% availability if you provide two independent power paths to every load. The power system for a utility has 99.9% availability.

Boeing seems to have learned a number of important lessons on all-electric systems, but there still seems to be a level of evolution needed to make it a mainstay. Give it 10 years on the 787 and then give it a shot for the next product.


User currently offlineDocLightning From United States of America, joined Nov 2005, 18712 posts, RR: 58
Reply 22, posted (9 months 2 weeks 2 days 15 hours ago) and read 3262 times:

Quoting lightsaber (Reply 20):
Really? Pneumatic system are notorious for taking more maintenance time than electrical (or even hydraulic). Did they screw up on the heating pads and having them burn out?

Any my job is now to design pneumatic components. So while I would *love* what you said to be true (job security), it is the opposite of my engineering experience on other projects though...

Was the entire type grounded for a problem in its pneumatic system? That's a pretty serious reliability issue. And please don't tell me that the battery is unrelated to the electrical system.

In fact, most of the delays in the program have revolved around the all-electric architecture.


User currently offlinebikerthai From United States of America, joined Apr 2010, 2013 posts, RR: 4
Reply 23, posted (9 months 2 weeks 2 days 10 hours ago) and read 3203 times:

Quoting DocLightning (Reply 22):

Was the entire type grounded for a problem in its pneumatic system? That's a pretty serious reliability issue.

Doc,

If you wait 10 years and look back at this incident, you may conclude that the grounding was an over reaction to something unknown.

To nit pick, the grounding was because of a safety concern (which may have come from both reliability and system design short fall) but not because of reliability in itself.

Beside, is it really true that many of the bugs and delays they are having with the 787 come from systems that were converted from pneumatic to electrical?

As for the battery fire issue, the battery was there for back-up. The system that replaced the pneumatic starting system didn't really fail did it?

bt



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlinePPVRA From Brazil, joined Nov 2004, 8876 posts, RR: 40
Reply 24, posted (9 months 2 weeks 2 days 8 hours ago) and read 3170 times:

Quoting trex8 (Thread starter):
"Although the 787's electric architecture is billed as a fuel saving innovation, Blair says, the actual reason it was selected was because the composite wing was too thin to accommodate a pneumatic system"

Doesn't a thinner wing save fuel?



"If goods do not cross borders, soldiers will" - Frederic Bastiat
User currently offlineStarlionblue From Greenland, joined Feb 2004, 16908 posts, RR: 67
Reply 25, posted (9 months 2 weeks 1 day 23 hours ago) and read 3078 times:

Quoting PPVRA (Reply 24):
Quoting trex8 (Thread starter):
"Although the 787's electric architecture is billed as a fuel saving innovation, Blair says, the actual reason it was selected was because the composite wing was too thin to accommodate a pneumatic system"

Doesn't a thinner wing save fuel?

Not necessarily. It depends on the specific wing shape and the operating speeds. For example, supercritical wings for transonic flight tend to be fatter than more non-supercritical ones.



"There are no stupid questions, but there are a lot of inquisitive idiots."
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