787 inflight structural breakup in 3....2....1....

[Procede]

My point was that in a transport-category aircraft the battery isn't so vital a component that it has to be the latest and greatest.

Unless you go for an all (or more) electric architecture.

ANA extends 787 suspension to 31 May

[flyboy2548m]

Unless you go for an all (or more) electric architecture.

Which still won't make the battery(ies) the main player. The main players will be generators, which will need to be more powerful (or there will be more of them). Case in point is the P-8, which, unlike the 738/9, uses two generators per engine rather than one.

[GlennAB1]

Batteries will be the main player when we get to this:
http://www.youtube.com/embed/oz3tzG9RxKI

Sugar Volt baby!!!

[flyboy2548m]

Batteries will be the main player when we get to this:
http://www.youtube.com/embed/oz3tzG9RxKI

Sugar Volt baby!!!

Dear God.

[GlennAB1]

What, you don't think Boeing's on the right track?

[Marc 1]

My point was that in a transport-category aircraft the battery isn't so vital a component that it has to be the latest and greatest.

Unless you go for an all (or more) electric architecture.

ANA extends 787 suspension to 31 May

Or you make a point about the advanced technology your airframe has and spend gazillions developing lightweight materials - then drop a bloody great lead acid battery (peukert effect will ensure it is larger than it needs to be) into it.

[Procede]

Which still won't make the battery(ies) the main player. The main players will be generators, which will need to be more powerful (or there will be more of them). Case in point is the P-8, which, unlike the 738/9, uses two generators per engine rather than one.

But you still need a lot more battery capacity for starting engines and emergencies. This is why the A350 could switch to NiCD and the 787 cannot.

[flyboy2548m]

But you still need a lot more battery capacity for starting engines and emergencies. This is why the A350 could switch to NiCD and the 787 cannot.

In nearly seven years of airline flying I'm yet to do a battery start.

[Gabriel]

Unless you go for an all (or more) electric architecture.

Which still won't make the battery(ies) the main player. The main players will be generators, which will need to be more powerful (or there will be more of them). Case in point is the P-8, which, unlike the 738/9, uses two generators per engine rather than one.

As I understand (which in all fairness is not much in this case), the APU driven generator(s) (that are your main source of electric energy if you have a dual flame-out) are much more powerful that in a traditional architecture, hence need much more power from the APU to operate, hence the APU needs much more power to start, hence the much more powerful battery.

[flyboy2548m]

As I understand (which in all fairness is not much in this case), the APU driven generator(s) (that are your main source of electric energy if you have a dual flame-out) are much more powerful that in a traditional architecture, hence need much more power from the APU to operate, hence the APU needs much more power to start, hence the much more powerful battery.

Gabriel, you're missing the point. Even if indeed this is an issue of needing a "much" more powerful battery, they still don't necessarily have to go with Li-ion. If that means using a Ni-Cad battery that's several hundred (or even a thousand) pounds heavier than most (I doubt that's anywhere near the case), that's still not an issue with an airplane this size.

[Procede]

Gabriel, you're missing the point. Even if indeed this is an issue of needing a "much" more powerful battery, they still don't necessarily have to go with Li-ion. If that means using a Ni-Cad battery that's several hundred (or even a thousand) pounds heavier than most (I doubt that's anywhere near the case), that's still not an issue with an airplane this size.

You would think that the weight penalty would be acceptable. The weight penalty on the A350 is 60 kg.
From what I have heard there isn't enough space in the current bay to retrofit the 787 with Ni-CD batteries. They would have to move the batteries to another area and redo the electrical interference certification...

[GlennAB1]

But you still need a lot more battery capacity for starting engines and emergencies.

Every transport catagory aircraft I know of has air starters for the engines and an electric starter for the APU.

[flyboy2548m]

Every transport catagory aircraft I know of has air starters for the engines and an electric starter for the APU.

Let's not bore people with facts.

[3WE]

Every transport catagory aircraft I know of has air starters for the engines and an electric starter for the APU.

Let's not bore people with facts.

Time out...the fact is, that the plane needs a battery...right? (or maybe "need" is too strong of a word, maybe the battery is just "very nice to have".)

I don't now what it truly needs it for, but the engineers figured out a reasonable size...and now the master plan is a fouled up and they need something bigger or heavier, or maybe they just need to refigure how to get by with less capacity...

anyway- fact is that it's quite the inconveinience.

[Procede]

Every transport catagory aircraft I know of has air starters for the engines and an electric starter for the APU.

Then you do not know the 787, as it uses starter generators on the engines as well.
http://www.boeing.com/commercial/aeroma ... 2012_q3/2/

[GlennAB1]

No, I don't know the 787.... So, does that make the battery(ies) the main player?

[flyboy2548m]

No, I don't know the 787.... So, does that make the battery(ies) the main player?

No, but that would explain the need for two APU Gens to power those 250VAC starter generators.

[Procede]

No, I don't know the 787.... So, does that make the battery(ies) the main player?

No, but that would explain the need for two APU Gens to power those 250VAC starter generators.

The APU is probably heavier because of that, which would require more power to start it. Maybe you can also start an engine straight from the batteries?
I'm not sure other which systems need to be fed in emergencies by the batteries. Next to most of the avionics probably flight controls (Electro-hydrostatic (backup) actuators) and pressurization.

[GlennAB1]

There's really much more to it than that, Ike. The aircraft's available on-board electrical power is 1.45 megawatts, which is five times the power available on conventional airliners. The most notable electrically powered systems include: engine start, pressurization, horizontal stabilizer trim, and wheel brakes. Wing ice protection is another new system; it uses electro-thermal heater mats on the wing slats instead of traditional hot bleed air.

[flyboy2548m]

There's really much more to it than that, Ike. The aircraft's available on-board electrical power is 1.45 megawatts, which is five times the power available on conventional airliners. The most notable electrically powered systems include: engine start, pressurization, horizontal stabilizer trim, and wheel brakes. Wing ice protection is another new system; it uses electro-thermal heater mats on the wing slats instead of traditional hot bleed air.

Still doesn't make the battery the be-all and end-all, does it?

[GlennAB1]

From Boeing: The electric start system affords maximum flexibility from a variety of power sources: APU generators, external power cart, and cross engine (opposite engine VFSGs).

[flyboy2548m]

Maybe you can also start an engine straight from the batteries?

I doubt it, since the starter mode apparently requires 250VAC. So, either way, you'd need an inverter.

[GlennAB1]

Ike, they ought to just take it out and throw it away... we don't need no stinking battery... really doesn't matter to me.

[flyboy2548m]

Ike, they ought to just take it out and throw it away... we don't need no stinking battery... really doesn't matter to me.

Glad we got that established. It seems at the very least they'll be throwing the Li-ion battery away for sure.

[3WE]

From Boeing: The electric start system affords maximum flexibility from a variety of power sources: APU generators, external power cart, and cross engine (opposite engine VFSGs).

http://www.amazon.com/Black-Decker-JUS5 ... ooster+Box
?