Airbus to Proceed With New A350 Jet

[cforst513]

anyone else think that they should concentrate on the problems that they have now with the A380 instead of moving onto new things? and do we REALLY need another freakin' airliner?!?

Link

 

[ToiletDuck]

My question is what's so great abou the 787? What's the overall design for? I heard that it will be composite so is it basically just a 767 that's a lot more efficient?

 

[say again]

My question is what's so great abou the 787? What's the overall design for? I heard that it will be composite so is it basically just a 767 that's a lot more efficient?

Key Words- MORE EFFICIENT!!!!!!:beer:

 

[coolyokeluke]

There are a lot of aging 767 airframes out there, and the 787 is Boeing's product offering to replace them, and airbi. The 787 is a clean sheet design, nothing taken from the 767. In the brutally competitive airline industry increased efficiency will be a very attractive attribute. Plus it's supposed to be nice for passengers, things like better air ciruculation, lower cabin altitude, increased humidity (is that going to cause mold problems?), bigger windows, mood lighting, more space in the overhead bins, etc.
Airbus had to work on making the A350 in order to not hand over market share to the 787.

 

[414Flyer]

And all the A350 is, is an updated A330.

 

[VNugget]

Warning Warning Airbus Vs Boeing Thread Alert

 

[say again]

Warning Warning Airbus Vs Boeing Thread Alert

Go Airboeingbus!!!!

 

[cforst513]

wait -- are you talking about the brasiliantonov airboeingbus or the dorniembraer airboeingbus?

 

[EagleRJ]

The Airbus effort to counter the 787 with another model is half-hearted at best. It's true that the 787 is a clean-sheet design, with new engines designed just for it.

The A350 is an A330 that makes more use of composite parts, and uses the engines being developed for the 787.

The problem is, Boeing is doing away with the use of bleed air in the 787, to let a more efficient bleedless engine to be used. Everything on the 787 that used to be pneumatic is going to be electric now. Pressurization is going to be done with electric air compressors, and anti-icing is going to be all electric. The engines will be started with starter/generators, like a King Air. To handle the electric loads, the 787 is going to have the most electrical generation capacity of any airliner- 1500 KVA total (in comparison, most airliners now have about 120 KVA in AC generation).

To cater to Airbus and the A350, GE and Rolls-Royce are trying to adapt their Gen-X and Trent 1000 engines to lose the extra electrical capacity and add a bleed air system. That's going to be hard to do while maintaining the efficiency that this new design is built around!

So, Airbus is offering to the market a rebadged old-school A330 that has some new composite parts, and engines that are producing bleed air that they weren't designed for. We'll see how efficient this design is compared to the 787. I'll bet the results will be disappointing, as will be A350 sales.

 

[ToiletDuck]

lemme ask you this. Is composite ready for such big design? I've only read a little on it and from what I've read it's kinda unpredictable. It's hard to tell the integrity of it and it degrades with UV rays. Aren't manufacturers worried about this?

 

[coolyokeluke]

Composites have been used in aircraft construction for quite a while now. I'm pretty sure they'll do it right.

 

[mzaharis]

What's interesting is that they started with a minimal modification of the A330, and have had to progressively revise it to have less and less commonality with the A330. They originally estimated 2 billion in development costs, then had to up it to 5 billion, as they reduced A330 commonality. I guess it shows how high the bar was set with the 787.

In other news, some people have claimed that it will be difficult for the bleedless engines to really save that much energy, purely by being bleedless. I'm thinking specifically of an article in AW&ST a few months ago. The engines gain in effeciency by not having to bleed off compressed air, but this is partially offset by the massive amount of power that the auxiliary generator is going to tap.

From the March 28, 2005 AW&ST:

"The comments may apply more to General Electric and Pratt & Whitney engines. The variable stators in their engines go much further up the compression chain. A General Electric official says bleed vs. electric "is a wash relative to the engine performance. It may have differing values to each airframer on how they do the installation and how much they need to extract from the engine." General Electric is selling the GEnx engine for both the 787 and the competing Airbus A350, which uses bleed air, and must be careful not to offend either customer's design."

Rolls Royce claimed that their 3-shaft engines are better equipped for this, because tapping off of the intermediate shaft is more efficient than tapping off the low-pressure or high-pressure shafts on a 2-spooler (GenX). I don't know if this just a manufacturer claim, but most of the sales so far have been RR, if I remember correctly.

 

[coolyokeluke]

Interesting post. Perhaps the advantage of electric vs. pneumatic (since you have to extract energy from the engines either way) if the electric isn't that much more efficient are in the ease of laying electrical lines vs. pneumatics, the associated fire detection/extinguishing that may be needed using pneumatics, weight savings of electric wiring vs. pneumatic plumbing, and more precise control. Pure speculation on my part. Any other ideas?

I know that Continental recently had an "ice cream party" hosted by GE for their upcoming partnership on the 787, so that's at least some orders for GE vs Rolls Royce.

What's interesting is that they started with a minimal modification of the A330, and have had to progressively revise it to have less and less commonality with the A330. They originally estimated 2 billion in development costs, then had to up it to 5 billion, as they reduced A330 commonality. I guess it shows how high the bar was set with the 787.

In other news, some people have claimed that it will be difficult for the bleedless engines to really save that much energy, purely by being bleedless. I'm thinking specifically of an article in AW&ST a few months ago. The engines gain in effeciency by not having to bleed off compressed air, but this is partially offset by the massive amount of power that the auxiliary generator is going to tap.

From the March 28, 2005 AW&ST:

"The comments may apply more to General Electric and Pratt & Whitney engines. The variable stators in their engines go much further up the compression chain. A General Electric official says bleed vs. electric "is a wash relative to the engine performance. It may have differing values to each airframer on how they do the installation and how much they need to extract from the engine." General Electric is selling the GEnx engine for both the 787 and the competing Airbus A350, which uses bleed air, and must be careful not to offend either customer's design."

Rolls Royce claimed that their 3-shaft engines are better equipped for this, because tapping off of the intermediate shaft is more efficient than tapping off the low-pressure or high-pressure shafts on a 2-spooler (GenX). I don't know if this just a manufacturer claim, but most of the sales so far have been RR, if I remember correctly.

 

[mzaharis]

I'd posted this info to the wrong thread last Friday:

I pulled up the old articles from aviationnow.com regarding the 787.

Some interesting points:

1. Pulling the power off of the intermediate shaft makes the Rolls engine less suseptible to compressor stalls (again, a claim that Rolls-Royce themselves make, but they back it up with a bunch of cool looking graphs ;-) ).

2. The aircraft requires 5 times as much electrical power as a normal airliner (!).

3. The only thing that bleed air is used for is engine cowling deicing - even wing deicing is electric.

4. The real advantage of bleedless engines is that bleed air from an engine is hotter and more compressed than optimal, mostly due to the fact that you can't take the bleed air off on the stages where there are variable stators, and you need to wait until a higher stage than optimal. Electric air compressors can be set to compress the air no more than necessary, and you needn't waste energy compressing air more than necessary for cabin compression.

5. They're using the generators as starter motors - this is really a limiting factor - to get the low speed torque required to start the engines, you must run much more current through the generator/starter motors than those motors are normally designed to handle.

6. Controlling all this power flowing through the aircraft is quite a trick - the controllers require liquid cooling.

 

[ToiletDuck]

Anything we say negative will probably have had a billion spent on it to make it better. I'm willing to say they've taken care of all these negtive aspects. It could be possible they could just groundstart each engine so it isn't requiring the planes electrical system to do so.

 

[EagleRJ]

Anything we say negative will probably have had a billion spent on it to make it better. I'm willing to say they've taken care of all these negtive aspects. It could be possible they could just groundstart each engine so it isn't requiring the planes electrical system to do so.

But that would make a windmilling start the only option for inflight restart. That's a Part 25 no-no.

It's not that difficult to design a starter-generator that is able to start a turbofan in the 60,000# thrust class. It's just that it hasn't been done before. If there's any problem getting that amount of power, it might be with the batteries. I'd guess that the engines will need to be started with either the APU or a GPU. The batteries alone won't hack it.

 

[mzaharis]

Anything we say negative will probably have had a billion spent on it to make it better. I'm willing to say they've taken care of all these negtive aspects. It could be possible they could just groundstart each engine so it isn't requiring the planes electrical system to do so.

Two things:

1. Groundstarts - one of the problems is that an electrical motor startup takes more current than the average groundstart cart has - they may need to use 2 groundstart carts. They're counting on the APU to supply juice for startups, even on the ground. (Source - same AvWeek article as in my previous post)

2. I have every confidence that Boeing will solve the challenges ahead of them; it's just interesting to realize how radical doing a nearly "all-electric" jet is from a design perspective, and how much it's exercising the engineers' frontal lobes.

I'm sorry if my post came off as a pessimistic assessment of the 787 - I think it'll be a very successful product. But, Boeing definitely hasn't taken the "easy way out", and I don't think some of the people over at a.net who say "just make airplane x (747-ADV, A350, etc.) bleedless and it'll be tons better" realize what's involved in doing that.

 

[Pedro]

Will the APU still have bleed air? If so that would be a way to start the engines, no bleeds required in the engine for it to have an air turbine starter...

I haven't read much about the 787, so I'm just asking.

 

[mzaharis]

Will the APU still have bleed air? If so that would be a way to start the engines, no bleeds required in the engine for it to have an air turbine starter...

I haven't read much about the 787, so I'm just asking.

The 787's "bleedless". The only thing that bleed air is used for is engine inlet deicing - everything else (cabin pressurization, engine starts, wing deicing) is electric, based on some MASSIVE generators on the engines. Engine starting is via the electric generators on the engines, which double as starter motors, nominally powered by electricity from the APU. The engines have no provision for pneumatic start. Pressurization is driven by electrically-driven air compressors. Deicing/anti-icing is performed with electric heat. From a systems standpoint, the aircraft is a really radical shift from prior, bleed-driven, airliner designs.

 

[mzaharis]

It's not that difficult to design a starter-generator that is able to start a turbofan in the 60,000# thrust class. It's just that it hasn't been done before. If there's any problem getting that amount of power, it might be with the batteries. I'd guess that the engines will need to be started with either the APU or a GPU. The batteries alone won't hack it.

Here's the quote from the AvWeek article:

"Making an electric starter replace the proven pneumatic starter is a top concern. If the generators weren't so large, it wouldn't make sense to use them as starters, but as it is, their size is driven by both roles. The problem is accelerating the large inertia and drag of a big turbofan in a competitive time. The typical Trent pneumatic starter motor makes 200 hp., Booth said. Both electric motors turn the engine and for a quick start are driven at 1.2 times the current rated for continuous generating. "Before, overload [was] rare on aircraft. Here we do it every start," says Robert W. Guirl, the 787 program director in Rockford. "