CeddP
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787 electrical architecture efficiency vs traditional systems

Sun Nov 10, 2019 6:02 pm

Hi all,

Does anyone have a number regarding efficiency of the overall electrical/bleedless architecture of the 787 vs a traditional equivalent? Do we know how much fuel saving is achieved by using this architecture?
I'd love to know as well how "good" each electric system is vs its hydraulic/pneumatic counterpart (wing anti-ice, brakes, air conditionning/pressurization, engine starters, electrically driven hydraulic pumps vs pneumatically driven...)

Thanks
 
BravoOne
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Re: 787 electrical architecture efficiency vs traditional systems

Sun Nov 10, 2019 7:51 pm

Don't hold your breath for an in-depth analysis as I suspect in varies all over the charts with a host of variables to boot. Seem to recall a number like 8-10%, but that was long time ago. Individual operators could have distintly different data to report.

As far a reliability you would have to look at the dispatch numbers which are quite good. Sorry I can't be more specific.
 
mmo
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Re: 787 electrical architecture efficiency vs traditional systems

Sun Nov 10, 2019 8:28 pm

Disclaimer: This is from the Boeing Aero publication and is from 2007. The aircraft is doing about 1.5-2.0% better than planned.
The article claims a 6% savings over a similar-sized aircraft. So with the additional improvement, it should be 7.5-8% improvement which on an individual basis is not much but on a fleet-wide basis it is a significant improvement. Then there are the maintenance savings with some of the major systems.

https://www.boeing.com/commercial/aerom ... _02_1.html
If we weren't all crazy we'd all go insane!
 
JayinKitsap
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Re: 787 electrical architecture efficiency vs traditional systems

Mon Nov 11, 2019 2:02 am

mmo wrote:
Disclaimer: This is from the Boeing Aero publication and is from 2007. The aircraft is doing about 1.5-2.0% better than planned.
The article claims a 6% savings over a similar-sized aircraft. So with the additional improvement, it should be 7.5-8% improvement which on an individual basis is not much but on a fleet-wide basis it is a significant improvement. Then there are the maintenance savings with some of the major systems.

https://www.boeing.com/commercial/aerom ... _02_1.html


Great article. Maintenance savings is a big part of it, initial assembly is also far easier. We will know the real answer about electrical architecture with Boeing's next clean sheet. If as successful as Boeing presents the next will have version 2.0 of the 787 electrical architecture. Electrical linear actuators or electro-hydraulic (pump at the unit) is replacing hydraulics throughout industry, the advent of the new motors and variable speed drives the troublesome gearboxes are going away.

Some data to consider as to why electrical is easier.
Bleed air uses a lot of Titanium, at $26/lb before doing anything to it makes copper look easy at less than $3/lb or Aluminum at $ 1.56/lb raw. A 6 KW motor running at 230V 3 phase takes (3) #20 wires for the 15A load. That is far easier and lighter than any kind of tubing. A 50KW motor would be 140A which would be (3) #1, still light compared to the tube.
 
gloom
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Re: 787 electrical architecture efficiency vs traditional systems

Mon Nov 11, 2019 10:28 am

I still think it's sort of urban legend, all these savings.

Notice no airplane designed after is all-electric. Instead, a couple of new planes (77X doesn't seem to be a case, since it's already been designed with air in mind) came into market, and they're all bleed planes.

There were topics here on forums, proving maintenance is not so cheaper as it's claimed to be. Ducts are simple, mechanical designs. Electric buses with air generation, not so.
Plus there are initial costs, I'm not quite sure which one is cheaper at design/build phases.

I'd rather hold the horses and see if anyone will follow this route.

Cheers,
Adam
 
Max Q
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Re: 787 electrical architecture efficiency vs traditional systems

Mon Nov 11, 2019 12:25 pm

gloom wrote:
I still think it's sort of urban legend, all these savings.

Notice no airplane designed after is all-electric. Instead, a couple of new planes (77X doesn't seem to be a case, since it's already been designed with air in mind) came into market, and they're all bleed planes.

There were topics here on forums, proving maintenance is not so cheaper as it's claimed to be. Ducts are simple, mechanical designs. Electric buses with air generation, not so.
Plus there are initial costs, I'm not quite sure which one is cheaper at design/build phases.

I'd rather hold the horses and see if anyone will follow this route.

Cheers,
Adam



What new large commercial jet transports have been designed after the 787 / A350 ?


None that I know of in the western world, it’s too early to tell If the concept of a mostly electric systems architecture is considered successful yet


The next clean sheet Boeing design will answer that question
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CeddP
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Re: 787 electrical architecture efficiency vs traditional systems

Mon Nov 11, 2019 1:31 pm

Thanks for the replies, this Aero article is quite nice indeed!

Regarding maintenance cost, the only sure thing is that Cabin Air Compressors and electric brakes are, still up to now, in the top ten list of unscheduled components removals
 
Lpbri
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Re: 787 electrical architecture efficiency vs traditional systems

Mon Nov 11, 2019 7:29 pm

Probably the main reason why CACs get replaced more often than they should is airlines don't know how to handle their airplanes on the ground. They leave them fully powered up with packs on for hours/days at a time. If they used GSE smarter, they would get a lot more life out of them.

The brakes themselves are not a problem. More often its harnesses and boxes that get replaced.
 
gloom
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Re: 787 electrical architecture efficiency vs traditional systems

Mon Nov 11, 2019 8:27 pm

Max Q wrote:
What new large commercial jet transports have been designed after the 787 / A350 ?


Couldn't find exact date for design closed - probably somewhere around 2005. A350 was clean sheet with bleed, Airbus claimed it's a better solution. Chinese did C919, and C929 is also a project with bleed. E2 or A220 would also be post 787, I think. I don't think any of new (or cosidered) engines was designed with bleedless architecture. So, based on what we learned and what we see, savings are not worth what it needs.

Since no other hard evidence is supported, I'll be happy to have one that can be checked, confirmed, and stating otherwise.

Cheers,
Adam
 
CeddP
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Re: 787 electrical architecture efficiency vs traditional systems

Mon Nov 11, 2019 10:58 pm

This brings me nicely to my next question : where Boeing went electric with the 787, what did Airbus do on the 350 for the equivalent systems?
Asked otherwise : appart from aerodynamic and engine improvements, how did Airbus increase other aircraft systems efficiency compared to previous generation?
 
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Starlionblue
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 5:20 am

CeddP wrote:
This brings me nicely to my next question : where Boeing went electric with the 787, what did Airbus do on the 350 for the equivalent systems?
Asked otherwise : appart from aerodynamic and engine improvements, how did Airbus increase other aircraft systems efficiency compared to previous generation?


Just to name some things that have improved from the A330 to the A350.

- Increase in Hydraulic pressure from 3000 to 5000PSI.
- Decrease in hydraulic systems from 3 to 2 thanks to the inclusion of self-contained hydraulic systems in some actuators. That way you can lose all main hydraulics and still fly.
- Simplified hydraulic architecture along with greater redundancy. Both systems now have one pump in each engine.
- Increase in engine generators from 2 to 4, which along with the necessary increased electrical output also gives greater redundancy
- Increase in AC voltage from 115 to 230. (115V systems also remain.)
- Simplification of emergency electrical generation.
- Deletion of trim tank, leading to greatly simplified fuel system.
- Cruise flap extension for center of lift control, replacing trim tank center of gravity control.
- Autopilot still available in situations where on the A330 it disconnects, e.g. alpha prot and dual engine flameout.
- Integration of datalink and other functions in main cockpit systems.
- Simplification of air data hierarchy, as well as more air data redundancy.
- Lower cabin altitude.
- More spacious flight deck with improved ergonomics and visibility.
- Improved radio and audio controls.
- FMS landing system, allowing non-precision approaches to be flown with ILS-like guidance.
- Automatic emergency descent.
- Integrated airport navigation function.
- Enhanced flight control in case of failures and degraded modes.
- Derotation law for enhanced comfort.
- Automatic rudder input with an engine out on takeoff.
- Higher maximum cruise altitude (for the -900).
- Higher cruise speed. 0.85 vs 0.82.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Max Q
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 6:51 am

What is this ‘derotation law for enhanced comfort’ ?
The best contribution to safety is a competent Pilot.
 
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Starlionblue
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 7:10 am

Max Q wrote:
What is this ‘derotation law for enhanced comfort’ ?


Controlled derotation logic on touchdown that was added to the Flare Law. It makes derotation smooth(er) and gives some protection from slamming the nose wheel down.

Some Airbus informational stuff I read says it "provides a comfortable nosewheel touchdown".
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
thepinkmachine
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 10:17 am

FWIW, I had an interesting conversation back in 2011. It was around the time when A350 design was finalized and they were starting the assembly of the first prototype, while Boeing was delivering first 787s to ANA.

I was in Toulouse back then and met one of Airbus engineers. He told me that Boeing had been very revolutionary with new technologies on the 787 and that they were bound for trouble sooner or later (mind you, that was before the Li batteries problem and other issues). In his words Airbus decided to adopt "wait and see" approach, ie. keep the systems more conventional, while letting Boeing trip over new problems. It's not like they said this new things were not worth it, but they were considered too risky to implement.

This seems to be the case - the 787 has more unconventional systems than any other airplane. We have to wait until the next clean sheet project to see which elements get adopted. A330NEO and 777X, 320NEO and 737MAX are not good examples, as in all these cases the main point the goal is to make use of the new engine technology, as cheaply and as quickly as practicable. Hence, changes in systems architecture are kept to the minimum.

However, I can already see several things shared by the 787 and 350, that will probably become the new standard:

- higher hydraulic operating pressure
- new electrical architecture with 4 smaller electrical generators (instead of 2 larger ones) and more electrical buses and 230VDC
- cruise flaps, no more c.g. control with trim tanks
- more "electrical" flight controls


As for the original questions and numbers - I seem to remember initial presentatnions from Boeing, back from 2006, or so (the thing was probably still called 7E7 and still had this lovely sharkfin tail, which got dropped later on). Back then Boeing was claiming efficiency increse of several percent due to the bleedless architecture and more electrics. Unfortunately I don't remember any actual numbers and don't know how much of the gains was 'eaten' later on, due to the added weight of the Liquid Cooling Systems and other stuff required by the new architecture. Also, the 787 engine is not completely "bleedless" - bleed air is still used for engine anti-ice and for engine stability...
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Starlionblue
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 10:45 am

thepinkmachine wrote:

However, I can already see several things shared by the 787 and 350, that will probably become the new standard:

- higher hydraulic operating pressure
- new electrical architecture with 4 smaller electrical generators (instead of 2 larger ones) and more electrical buses and 230VDC
- cruise flaps, no more c.g. control with trim tanks
- more "electrical" flight controls




While you are absolutely right on the concepts, the new generators are not really smaller, as in less powerful, or at least not by much. A350 has 4 x 100 KVA engine-driven generators whilst the A330 has 2 x 115 KVA.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
thepinkmachine
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 10:58 am

Starlionblue wrote:

While you are absolutely right on the concepts, the new generators are not really smaller, as in less powerful, or at least not by much. A350 has 4 x 100 KVA engine-driven generators whilst the A330 has 2 x 115 KVA.


Fair point. I don’t know the power output of the 787 generators (Boeing doesn’t consider it relevant for pilots, so no info in the FCOM), but they are probably similar to the 350.

It a good question, however, whether they used 4 instead of 2 because it’s more efficient, more redundant, or simply because at the moment generators with higher output are not available...
"Tell my wife I am trawling Atlantis - and I still have my hands on the wheel…"
 
CeddP
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 11:16 am

Starlionblue wrote:
- Increase in engine generators from 2 to 4, which along with the necessary increased electrical output also gives greater redundancy

Do you have any idea which system specifically needs this increased output?

Starlionblue wrote:

While you are absolutely right on the concepts, the new generators are not really smaller, as in less powerful, or at least not by much. A350 has 4 x 100 KVA engine-driven generators whilst the A330 has 2 x 115 KVA.

Did they go for the variable frequency on those 4x100KVA or still with constant speed drive?

thepinkmachine wrote:
Fair point. I don’t know the power output of the 787 generators (Boeing doesn’t consider it relevant for pilots, so no info in the FCOM), but they are probably similar to the 350.

It a good question, however, whether they used 4 instead of 2 because it’s more efficient, more redundant, or simply because at the moment generators with higher output are not available...

In the aero article linked earlier, we can see on the electrical schematics (page 3) 2 X 250 KVA per engine + 2 X 225 for the APU. This is more than double compared to the 350 indeed :shock:
 
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Starlionblue
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 11:24 am

CeddP wrote:
Starlionblue wrote:
- Increase in engine generators from 2 to 4, which along with the necessary increased electrical output also gives greater redundancy

Do you have any idea which system specifically needs this increased output?

Starlionblue wrote:

While you are absolutely right on the concepts, the new generators are not really smaller, as in less powerful, or at least not by much. A350 has 4 x 100 KVA engine-driven generators whilst the A330 has 2 x 115 KVA.

Did they go for the variable frequency on those 4x100KVA or still with constant speed drive?

thepinkmachine wrote:
Fair point. I don’t know the power output of the 787 generators (Boeing doesn’t consider it relevant for pilots, so no info in the FCOM), but they are probably similar to the 350.

It a good question, however, whether they used 4 instead of 2 because it’s more efficient, more redundant, or simply because at the moment generators with higher output are not available...

In the aero article linked earlier, we can see on the electrical schematics (page 3) 2 X 250 KVA per engine + 2 X 225 for the APU. This is more than double compared to the 350 indeed :shock:


The reason for increased output? Much larger PTV screens? ;) Well, that's part of it. I bet the galleys use more power too.

The gennys are variable frequency on the A350.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
thepinkmachine
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 12:14 pm

CeddP wrote:
In the aero article linked earlier, we can see on the electrical schematics (page 3) 2 X 250 KVA per engine + 2 X 225 for the APU. This is more than double compared to the 350 indeed :shock:


That's a heck of a powerplant. 2.5 times as much as the 350, more than 4 times as the 330.

Actually, comparison to the A330, which is exactly the same size and must have a similar total energy consumption (of all kinds), gives us an idea of how much electricity replaced other sources of power (bleed, hydraulics).

I suspect the biggest users on the 787 are the CACs, then maybe large motor conrollers powering all sorts of electrical stuff and eqt. cooling. Don't know for sure, as the 787 gives pilots pretty scant information as to the inner workings of its systems. A lot can be dug out thru maintenance pages, though. Will try to have a look next flight.

As for the CACs mentioned before, they used to give a lot of trouble to the maintenance, but they seem to have improved. During my 1.5 year of flying the thing, I have seen CAC inop maybe once, or twice. Maintenance people seem to concur, that the CACs got better lately (and they have been dealing with the 787 since 2012 where I fly).

My only caveat is that CACs are quite inefficient on ground. Due to electrical shedding normally only 2 CACs operate due to electrical load shedding and they sometimes don't deliver enough power to cool down the cabin full of people. This was never an issue on the 330, which uses APU bleed. Once airborne, 4 CACs operate and the system works as advertised...
"Tell my wife I am trawling Atlantis - and I still have my hands on the wheel…"
 
thepinkmachine
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 2:24 pm

Regarding other 'electrified' systems on the 787:

- Electric brakes work very well. No hydraulic accumulators, no need to pressurize hydraulics for parking brake operation. Just push the pedals and they work, also not losing their grip when elec power is out. Strangely enough, they work on 28VDC. Another neat feature is that during taxi at low speed only half of the wheels are braked during each application, which greatly reduces brake wear. Not sure if this feature would be possible on normal, hydraulic brakes. One thing that's missing is BTV that is implemented on the A380 and 350. Boeing initially planned to provide it on the 787 but for some reason didn't


- Electric starters are very cool as well. You normally start two engines at the same time, all four VFSGs providing power simultaneously. The starting currents must be eye-watering, you can almost feel the electrical components frying during start :). If APU is not available, up to 3 external power sources may be connected, 1 dedicated to engine start. No Air Starter required

- Electrical system does a lot of automatic load-shedding. Load shedding is nothing new, but 787 takes it a step further. Rather than shedding entire electrical bus at times of high load (eg. galley power, IFE) it sheds the individual, non-essential pieces of equipment, depending on the phase of flight and available power sources (eg. fuel pumps, lights, CAC's etc). Most of the time it is transparent to the pilot

- Electrically powered hydraulics - no issues, only some strange system logic, precluding eg. single engine taxi out

- Before powering down the 787, at up to 22 minutes on APU/EXT power are needed to let the PECS (Power Electronics Cooling System) cool the electronics. Otherwise you risk damage to the electrical system, and/or degrading the cooling liquid

- APU fuel consumption is very high, up to 400kg/hr. Twice as much as on the A330. Since the electrical system doesn't 'like' poor quality ext power, APU is used more than in conventional A/C.


Dispatch reliability used to be the problem at the beginning, but it's good at the moment, most of the time it works pretty good - except for those pesky RR engines, but that's another story.
"Tell my wife I am trawling Atlantis - and I still have my hands on the wheel…"
 
milhaus
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 4:22 pm

Hello, I am on b878 B1 course right now. Electrical system performance, each of four VFSG normally supplies 250kVA, in overload condition it can supply 312kVA for five minuts or 437,5kVA for five seconds. Each weights 94kg dry and it has oil system with FOHE( fuel oil heat exchanger) and AOHE( air oil heat exchanger)
 
CeddP
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 4:30 pm

Starlionblue wrote:
The reason for increased output? Much larger PTV screens? ;) Well, that's part of it. I bet the galleys use more power too.

C'mon, you forgot about mood lighting in the toilets! :duck:

thepinkmachine wrote:
As for the CACs mentioned before, they used to give a lot of trouble to the maintenance, but they seem to have improved. During my 1.5 year of flying the thing, I have seen CAC inop maybe once, or twice. Maintenance people seem to concur, that the CACs got better lately (and they have been dealing with the 787 since 2012 where I fly).

My only caveat is that CACs are quite inefficient on ground. Due to electrical shedding normally only 2 CACs operate due to electrical load shedding and they sometimes don't deliver enough power to cool down the cabin full of people. This was never an issue on the 330, which uses APU bleed. Once airborne, 4 CACs operate and the system works as advertised...

What about actual setting of cabin occupants in flight? I know CACs suffered from surges when cabin occupants was too low, leading some operators to set a fixed value in the system equals to max cabin occupants. Is it your SOPs as well?

thepinkmachine wrote:
Electrically powered hydraulics - no issues, only some strange system logic, precluding eg. single engine taxi out

Can you expend on this a little bit? Some operators practice engine out taxi-in though. What difference makes it possible?

thepinkmachine wrote:
APU fuel consumption is very high, up to 400kg/hr. Twice as much as on the A330. Since the electrical system doesn't 'like' poor quality ext power, APU is used more than in conventional A/C.

Talking about that, do you know what would be APU fuel burn on ground with packs OFF vs ON?

milhaus wrote:
Hello, I am on b878 B1 course right now. Electrical system performance, each of four VFSG normally supplies 250kVA, in overload condition it can supply 312kVA for five minuts or 437,5kVA for five seconds. Each weights 94kg dry and it has oil system with FOHE( fuel oil heat exchanger) and AOHE( air oil heat exchanger)

Welcome to the discussion and please feel free to answer any of those questions!! :biggrin:
 
thepinkmachine
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Re: 787 electrical architecture efficiency vs traditional systems

Tue Nov 12, 2019 7:36 pm

CeddP wrote:

What about actual setting of cabin occupants in flight? I know CACs suffered from surges when cabin occupants was too low, leading some operators to set a fixed value in the system equals to max cabin occupants. Is it your SOPs as well?


Haven't heard of it, but the cabin crew do in fact always set max no. of occupants (it's in their computer, flight deck have no control over it). Perhaps they've been taught to do so, because of the CAC surges. I'm not, however, aware of any AD, or bulletin recommending this.

thepinkmachine wrote:
Electrically powered hydraulics - no issues, only some strange system logic, precluding eg. single engine taxi out

Can you expend on this a little bit? Some operators practice engine out taxi-in though. What difference makes it possible?


I don't want to go too deeply into the system logic, but basically both engines have to be started in order for the C hyd pumps to run. You don't have nosewheel steering until you start both engines.

For taxi in, when one engine is shut down, the C hyd system continues to operate normally, so this isn't an issue. Then again, the APU burns around 60% of 1 engine fuel consumption at idle, which significantly reduces potential savings for s.e. taxi in. OTOH S.e. taxi without the APU is not recommended due to electrical load shedding. So all in all, there are several things to consider, which differ from more conventional airplanes

thepinkmachine wrote:
APU fuel consumption is very high, up to 400kg/hr. Twice as much as on the A330. Since the electrical system doesn't 'like' poor quality ext power, APU is used more than in conventional A/C.

Talking about that, do you know what would be APU fuel burn on ground with packs OFF vs ON?


Strangely enough, packs ON or OFF don't make a significant difference - maybe 20-40kg/h

milhaus wrote:
Hello, I am on b878 B1 course right now. Electrical system performance, each of four VFSG normally supplies 250kVA, in overload condition it can supply 312kVA for five minuts or 437,5kVA for five seconds. Each weights 94kg dry and it has oil system with FOHE( fuel oil heat exchanger) and AOHE( air oil heat exchanger)
.

Good stuff, all additional info is very welcome
"Tell my wife I am trawling Atlantis - and I still have my hands on the wheel…"
 
milhaus
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Re: 787 electrical architecture efficiency vs traditional systems

Wed Nov 13, 2019 4:04 pm

Hello I have aditional facts about electrical systems. Main network is 235V variable frequency, which is produced by VFSG and apu generators. There also two autotransformers which converts from 235V to 115V variable frequency or only with GPU connected 15V To 235V. There are also four transformer rectifier units which convert 235V variable frequency to 28V DC. Then we have four ATRU which are autotransformer rectifier unit that convert 235V AC to +/- 270V DC and four BPSU that converts 28VDC to+/-130 V DC for brake use. Last transformer is GATU which converts 235V DC to 115V DC for aft galley equpment.
 
milhaus
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Re: 787 electrical architecture efficiency vs traditional systems

Wed Nov 13, 2019 4:07 pm

I forgot, some of tranformers are cooled by liquid and are so heavy that You need some special equipment for removal and instalation. It is hard to imagine that this layout can save some weight.
 
kalvado
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Re: 787 electrical architecture efficiency vs traditional systems

Thu Nov 14, 2019 1:34 pm

milhaus wrote:
I forgot, some of tranformers are cooled by liquid and are so heavy that You need some special equipment for removal and instalation. It is hard to imagine that this layout can save some weight.

Reducing size and weight of power converters is an on-goiing challenge. From your description, it sounds like Boeing went conservative way and they have plenty of opportunity even with current technology
 
milhaus
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Re: 787 electrical architecture efficiency vs traditional systems

Sat Nov 16, 2019 9:10 pm

I have to study APU at friday, it is also different from other APUs as it does not have bleed as expected. Strangest thing is that fuel pump is not powered from gearbox but it is ran by 28V dc el motor and APUC which is APU controler controls fuel supply by controliing motor speed, no fuel metering valve installed.
 
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DocLightning
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Re: 787 electrical architecture efficiency vs traditional systems

Sat Nov 16, 2019 10:16 pm

gloom wrote:
I still think it's sort of urban legend, all these savings.

Notice no airplane designed after is all-electric. Instead, a couple of new planes (77X doesn't seem to be a case, since it's already been designed with air in mind) came into market, and they're all bleed planes.


Mr. Leahy of Airbus said that Airbus decided not to follow suit with the A350 primarily because of concerns about reliability. Boeing undertook an enormous project by choosing their all-electric architecture for the 787 and they paid an enormous price for it. Remember the fire in the electrical bay? Remember the battery debacle? After the entire A380 debacle, JL did not want to take any unnecessary risks with the A350 and so they stuck to a conventional architecture.

So it seems that Airbus decided to let Boeing stick their neck in that noose first and see what happened. It would not shock me if Airbus's next clean-sheet design uses that architecture. Boeing will almost certainly use it on their next clean-sheet design now that they've smoothed out all the wrinkles.

An aerospace engineering friend told me that the big advantage of an all-electric architecture comes during the takeoff and climb phases and less so during cruise. So given that Boeing's next clean-sheet design will probably be geared at short-medium haul, all-electric would be a bigger advantage if what my friend said was true.
-Doc Lightning-

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trex8
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Re: 787 electrical architecture efficiency vs traditional systems

Sun Nov 24, 2019 11:56 pm

When the 787 was almost ready for EIS after delays from rollout there was an excellent article in either FI or AWST discussing the improved "efficiencies" of the 787 vs previous (ie 767) jets. They quoted someone from IIRC Hamilton Sundstrand who makes a big chunk of the 787 s electrical system saying there were likely to be minimal if any fuel efficiencies from electrical generation vs bleed air as the generators were so big and heavy but there would likely be significant potential longterm lower maintenance costs. Of the 20% better fuel efficiency likely from the 787 vs 767, low teens would be from the new generation engine and the rest of the 6-7% savings almost equally between better aerodynamics, CFRP weight savings and bleedless design.
 
milhaus
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Re: 787 electrical architecture efficiency vs traditional systems

Wed Nov 27, 2019 7:50 pm

Fyi electrical wing antiicing system has three modes of operation: antiice input power 165kW, limited antiice 125kW, deice 45kW.

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Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos