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Topic: Boeing Twin Aisle Light Jet Economics
Username: TomB
Posted 2011-03-22 09:54:00 and read 17504 times.

Randy Tinseth, Boeing’s Vice President of Marketing was at the Asian Aerospace 2011 conference in Hong Kong on March 9th and Daniel Tsang of Aspire Aviation reported on it.

http://www.aspireaviation.com/2011/0...1/boeing-twin-aisle-737x/#comments

Randy Tinseth talked about the possibility of Boeing launching a light twin aisle airplane (B-797?) and these economic facts were reported in the article.

“Airbus faces a bigger issue here than Boeing since the 737NG has a 5% fuel burn advantage versus the existing A320 family aircraft, from the data that I have seen from the airlines, not Boeing” David Tsang – the author in comment #2.

Boeing 737 Re-engined versus B-737NG:

Fuel Burn Savings 11-12%
Increase Price and Depreciation ??
Direct Operating Cost Savings 2-3%

Airbus 320NEOversus A-320:

Fuel Burn Savings after Strengthening the Outer Wing Box 7%
Increase Price and Depreciation $ 6 Million per Aircraft?
Direct Operating Cost Savings (depends upon engine) 2-5%

Boeing New Light Twin Aisle Aircraft versus B-737NG:

Fuel Burn Savings (per ASM?) 15-20%
Airframe Maintenance Cost Savings 20-30%
Increase Price and Depreciation A Given
Cash Operating Cost Savings (per ASM?) 10-11%
Direct Operating Cost (with depn.) Savings “Significantly Lower”

Tinseth also said the twin aisle light twin would have reduced turnaround times vs. the B-737NG and could thus operate one more revenue generating flight per day. It would also have larger cargo capacity and be able to generate more cargo revenue. The net income of the Boeing twin aisle aircraft would be substantially higher than the A-320NEO owing to the extra revenue generated by flying significantly more cargoes, operating an extra sector per day as well as the additional (10-15%?) fuel burn savings over and above the A-320NEO.

Now if Boeing could have biological twin pilots and two sets of twin flight attendants to go with their twin aisle, twin engine aircraft, they would have the start of a wonderful marketing campaign for the new aircraft.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: pylon101
Posted 2011-03-22 10:29:07 and read 17420 times.

Wow, I like this new and clear definition: Twin Aisle Light Jet.
It states that it is going to be a completely new aircraft.
So comparisons to 767-200 or 757-200 are just irrelevant - at least until we see some result.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: LAXDESI
Posted 2011-03-22 15:02:27 and read 16987 times.

Quoting TomB (Thread starter):
Boeing New Light Twin Aisle Aircraft versus B-737NG:

Fuel Burn Savings (per ASM?) 15-20%
Airframe Maintenance Cost Savings 20-30%
Increase Price and Depreciation A Given
Cash Operating Cost Savings (per ASM?) 10-11%
Direct Operating Cost (with depn.) Savings “Significantly Lower”

Based on the above numbers, I think the twin aisle 797 that is being proposed has to be a 2-2-2 layout. I have my doubt about fuel burn savings reaching 20% with two aisles. However, it looks like most of the cash operating cost savings are from reduction in maintenance cost.

I can see a single aisle replacement of 737 achieving 20% reduction in fuel burn, but a twin aisle is much less likely to do that.

Assuming the twin aisle 797 achieves only 12-15% reduction in fuel burn and with fuel at 30% of operating cost, a cash operating saving of 9% is more likely per trip. Add to that one extra revenue trip per day due to the twin aisle, as per the link in OP, the twin aisle does make economic sense if the net price is not too far from the current NB offerings.

So a twin aisle 797 starting at 180 seats(with transatlantic range?) and NEO for the current 73G and 738 would nicely cover the 140-230 seat NB market.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: cygnuschicago
Posted 2011-03-22 15:11:19 and read 16944 times.

Quoting LAXDESI (Reply 2):
Based on the above numbers, I think the twin aisle 797 that is being proposed has to be a 2-2-2 layout.

I just don't see a 2-2-2 ever being practically used by the majority of purchasers. It will go the same way that 3-2-3 went on the 787.

If Boeing launches a 2-2-2, you will see one of two things happen:
1) Airlines will put in 2-3 in business class and 3-3 with wider seats and aisles in coach, or,
2) Airlines will insist on a slightly wider fuselage during design and then put in 2-3 in business class and 2-3-2 in coach.

The turnaround time from a twin-aisle is a red-herring, especially in the US. There are too many delays in the system to get an extra leg in with quicker turnaround time. The only way I see an extra leg is if Boeing is proposing a return to the SonicCruiser model with higher cruise speeds.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: LAXDESI
Posted 2011-03-22 15:33:50 and read 16845 times.

Quoting cygnuschicago (Reply 3):
The turnaround time from a twin-aisle is a red-herring, especially in the US. There are too many delays in the system to get an extra leg in with quicker turnaround time.

I don't know enough to comment on the issues you raise. I have wondered whether other aspects of a turnaround like catering, refueling, and baggage loading/unloading require a minimum amount of time that is not any less than the current boarding time for passengers. Does anyone know?

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: aklrno
Posted 2011-03-22 16:01:08 and read 16761 times.

I know how WN can shave several minutes off passenger load and unload times without doing anything to the equipment at all.

They already have free baggage which encourages fewer carry-ons, but there is still a lot of delay while people stuff their things into the bins and then try to retrieve them at the end of the flight. The problem is that no one enjoys the 20-30 minute wait at baggage claim. Their ground crews leave the unloaded bags on the carts at the gate until they have loaded the outgoing bags (for fast turnaround). If they had a couple of people at each station that could drive the loaded cart to the belt and unload it immediately I (and lots of others) would be happy to check bags more often.

When I'm on a flight where I get priority bag service I often check my bag. I rarely have a problem, and I enjoy the ease of travel without it. The airline gets the advantage of a faster turn. Doesn't everyone win?

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: LAXDESI
Posted 2011-03-22 23:14:07 and read 16356 times.

Southwest's take on twin aisle 797. It is hard to imagine how it would work for a 150 seat aircraft. It might work for a 180 seat aircraft.
http://www.flightglobal.com/articles...-discuss-new-light-twin-aisle.html

Quote:
"I think a lot of that may very well depend on the size of the aircraft," Kelly told attendees at the JP Morgan Aviation, Transportation and Defense conference. "Maybe a twin-aisle doesn't work for a 137-seater [the size of Southwest's Boeing 737-700s], but maybe it does for a 150-seater".

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Baroque
Posted 2011-03-23 00:16:55 and read 16233 times.

Quoting TomB (Thread starter):
economic facts

If you start on those as "facts" goodness knows where you will be when you get into projections.

Why not check those "facts" against the real numbers that Mandala499 has posted in a number of threads.

Building on quicksands can be dangerous to your structure.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: carbon787
Posted 2011-03-23 10:04:21 and read 14414 times.

I am sure that Boeing has done its homework in regards to a twin aisle layout, be it 2-2-2, 2-3-2 or whatever.
I think we can safely assume that Boeing has held many discussions with prospective airlines as to the layout of the '797' cabin.
So if it turns out to be a 2-2-2, then that is obviously what the majority of the airlines Boeing has spoken with want and the economics of such a design is the way to go.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: AADC10
Posted 2011-03-23 10:25:14 and read 14353 times.

Quoting TomB (Thread starter):
Boeing New Light Twin Aisle Aircraft versus B-737NG:

Fuel Burn Savings (per ASM?) 15-20%
Airframe Maintenance Cost Savings 20-30%
Increase Price and Depreciation A Given
Cash Operating Cost Savings (per ASM?) 10-11%
Direct Operating Cost (with depn.) Savings “Significantly Lower”

You have to take these number with a grain of salt. As shown by previous product launches, the numbers are driven more by the marketing department than engineering.

I also find it difficult to believe that 2-2-2 seating would actually hold up. The 787 was marketed as being able to give passengers one of their most requested items in coach, their own armrest at 8 abreast. Long before anyone has taken delivery however, most airlines have already committed to 9 abreast. The big risk of 2-2-2 is that for an airline like WN it might allow them to squeeze in one additional turn per day but since frontal area is the largest component of drag someone could build an aircraft with similar technology and a conventional narrowbody profile that could beat a 2-2-2 797 in efficiency. Since 7 abreast single aisle is not allowable the 2-2-2 797 operator would be stuck with an aircraft that would only pay off on short flights.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: mandala499
Posted 2011-03-23 10:44:36 and read 14318 times.

Regarding:

Quoting Baroque (Reply 7):
If you start on those as "facts" goodness knows where you will be when you get into projections.

Why not check those "facts" against the real numbers that Mandala499 has posted in a number of threads.

and:

Quoting TomB (Thread starter):
these economic facts

One must be careful on the assumptions used...
On the 738W vs 320, the numbers based on the FPPM (and FCOM Performance Dispatch section) on the NG and FCOM2 (A320 CFM56-5B and V2500-A5), the following are the comparisons (based on LRC and optimum altitudes, zero reserve).


(Note 739W should read as 738W above)


The above, is FACT (based on the numbers in certified manuals)
So, it really does depend on the assumptions used.

So I wouldn't take it at face value and treat it as gospel, nor would I slam what Boeing said as "quicksand"...

Now... When talking about:

Quoting TomB (Thread starter):
Tinseth also said the twin aisle light twin would have reduced turnaround times vs. the B-737NG and could thus operate one more revenue generating flight per day. It would also have larger cargo capacity and be able to generate more cargo revenue. The net income of the Boeing twin aisle aircraft would be substantially higher than the A-320NEO owing to the extra revenue generated by flying significantly more cargoes, operating an extra sector per day as well as the additional (10-15%?) fuel burn savings over and above the A-320NEO.

Reduced turnaround based on?
If one operates in and out of an airport with a nice long runway, in idyllic apron position... or even better, DEN style airport... then brake cooling isn't an issue. When you operate from shorter runways, even with brake fans and operating in hot and humid environments, your twin aisle turnaround advantage is mute if the brakes won't cool down!

Quoting cygnuschicago (Reply 3):
The turnaround time from a twin-aisle is a red-herring, especially in the US.

I've read enough damn marketing material to say, yes, damn red herring... be it Boeing or Airbus marketing material.

Quoting LAXDESI (Reply 4):
I don't know enough to comment on the issues you raise. I have wondered whether other aspects of a turnaround like catering, refueling, and baggage loading/unloading require a minimum amount of time that is not any less than the current boarding time for passengers. Does anyone know?

15 mins on the parking stand is achievable if it's a no catering turnaround, and not on a transit stop... be you in a Boeing or an Airbus narrowbody. However, most airlines would use 20-25 mins as the minimum time on the parking stand for a standard narrowbody on a full turnaround.

Mandala499

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: airfrnt
Posted 2011-03-23 10:47:06 and read 14304 times.

I find it amusing that the OP is being attacked for quoting numbers at a aviation conference. AvB continues.

Quoting TomB (Thread starter):
Tinseth also said the twin aisle light twin would have reduced turnaround times vs. the B-737NG and could thus operate one more revenue generating flight per day.

People are trying to downplay this, but this is huge. An additional flight a day on the existing medal is a large advantage for carriers. On top of that, factor in that Airlines are increasingly moving to carry-on only, with additional revenue generated by checked bags fee. A 2-2-2 (which I think every carrier in the world will turn into 2-3-2) has a additional two center-line luggage areas. That's a big deal for carriers that are wasting a lot of time having to pack bags after passengers are loaded.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: LAXDESI
Posted 2011-03-23 11:17:30 and read 14223 times.

Quoting mandala499 (Reply 10):
15 mins on the parking stand is achievable if it's a no catering turnaround, and not on a transit stop... be you in a Boeing or an Airbus narrowbody. However, most airlines would use 20-25 mins as the minimum time on the parking stand for a standard narrowbody on a full turnaround.

Thanks.

So how long does it take to deboard/board passengers currently on a NB? How long would it take with two aisles with additional bins in the center.

If it takes nearly 35 minutes to deboard/board current NBs, then the saving from a two aisle NB, say 10 minutes, is not useful as the minimum time on parking stand becomes an issue. Perhaps larger cargo door would help.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: AirNZ
Posted 2011-03-23 11:43:47 and read 14146 times.

Quoting cygnuschicago (Reply 3):
The only way I see an extra leg is if Boeing is proposing a return to the SonicCruiser model with higher cruise speeds.

Without going SS how much higher on cruise speeds could you go that would make it realistic to get in an extra rotation a day? I can't see it myself.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: mandala499
Posted 2011-03-23 11:59:43 and read 14101 times.

Quoting LAXDESI (Reply 12):
So how long does it take to deboard/board passengers currently on a NB? How long would it take with two aisles with additional bins in the center.

On using both front and rear doors, the 320 can do a turnaround with 180pax in 25mins on the gate. This can be done on a routine basis.
The board/deboard process only itself (excluding stairs/headcount/cleaning, etc) can be done in 11 mins...
When using the front door only, this is achievable, but pushing it slightly.

How much faster on a twin aisle? Dunno!

Mandala499

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: LAXDESI
Posted 2011-03-23 12:13:03 and read 14055 times.

Quoting mandala499 (Reply 14):
The board/deboard process only itself (excluding stairs/headcount/cleaning, etc) can be done in 11 mins...
When using the front door only, this is achievable, but pushing it slightly.

How much faster on a twin aisle? Dunno!

If your numbers are correct on total turnaround time(25 mins.) and deboarding/boarding(11 mins.), then the bottleneck is in other aspects of a turnaround and not necessarily in deboarding/boarding. So saving time on deboarding/boarding with two aisles may not really save much time on a turnaround.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: tsugambler
Posted 2011-03-23 12:13:36 and read 14054 times.

Quoting mandala499 (Reply 10):
your twin aisle turnaround advantage is mute

I think you mean "moot."

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: parapente
Posted 2011-03-23 12:15:16 and read 14046 times.

What about slot times? If (as most are) it's a busy airport - then you have allocated slot times.If you miss your slot then you have to wait.Furthermore when you get off the apron there is usuall a stack of aircraft waiting anyway.

If you try and "squeeze" a shorter time and for one (of a variety ) of reasons you are late then not only do you miss your slot but the whole of the days schedule is mucked up - and your economics is shot to pieces . It seems too much of a risk no?

BTW the reason that sometimes getting off a plane is slow is when someone (say in the middle) is slow getting their bags out of the locker - there's always one.The issue is nobody can get past,thus backing up the queue.Well on a twin aisle you now double the chances of someone in the middle doing this (it only takes one!).So not sure where 2 aisles gets you really.You cannot base shorter turnround times (and slots) unless you are 99% sure you can do it.Don'tr see how this guarantees this.

I accept that if you have fore and aft doors then it is easy.But that is equally true of a single aisle! I suppose Ryan air is best for double door use as they don't use air bridges in the first place!

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: btblue
Posted 2011-03-23 12:18:08 and read 14025 times.

Quoting airfrnt (Reply 11):
People are trying to downplay this, but this is huge. An additional flight a day on the existing medal is a large advantage for carriers. On top of that, factor in that Airlines are increasingly moving to carry-on only, with additional revenue generated by checked bags fee. A 2-2-2 (which I think every carrier in the world will turn into 2-3-2) has a additional two center-line luggage areas. That's a big deal for carriers that are wasting a lot of time having to pack bags after passengers are loaded.

Spot on.

Airlines like Ryanair (who, have been quiet of late) etc would much rather milk as much flying time as possible out of their aircraft (as any airline would).

Twin aisle, 2x3x2 (1 seat more than the 737, the model I believe we'll see) speedy boarding, disembarkation and plenty of room for you to pack your OWN bags. If all of this cut 10 minutes off a turnaround, that's a fair amount of time in the day.

When I fly (european, 1 - 2.5 hours), I see a LOT of people heading straight off the plane and out the airport - bypassing the carousel.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: flipdewaf
Posted 2011-03-23 12:30:13 and read 13980 times.

Quoting parapente (Reply 17):
BTW the reason that sometimes getting off a plane is slow is when someone (say in the middle) is slow getting their bags out of the locker - there's always one.The issue is nobody can get past,thus backing up the queue.Well on a twin aisle you now double the chances of someone in the middle doing this (it only takes one!).So not sure where 2 aisles gets you really.You cannot base shorter turnround times (and slots) unless you are 99% sure you can do it.Don'tr see how this guarantees this.

It actually decreases you chances of being stuck, id like to say by half but im pretty sure its not. If someone is blocking the isle then they are only blocking one isle and not two.

On the 2-2-2 matter, Boeing won't do it. Anything they can do to mitigate the increase in fuel burn on a wider x-section Airbus can do to the narrower one and trump Boeing on the CASM stakes. Boeing aren't that daft.

Fred

P.S. Happy to be proved wrong in the end, would love to see something new looking in the sky.

[Edited 2011-03-23 12:34:04]

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: mandala499
Posted 2011-03-23 12:33:26 and read 13977 times.

Quoting parapente (Reply 17):
I suppose Ryan air is best for double door use as they don't use air bridges in the first place!

Using front and rear doors, is quicker, but not by much. When the weather's nice and dry... yes...
One carrier I know, has no difference on turnarounds of 25 mins whether it's using front only, or front and rear.
But when it's really wet, the pax flow through the doors can add to at least another 5 minutes... people tend to walk up the stairs slower with their wet shoes    and only 1 door is used... (no probs when on a jetbridge).

Quoting LAXDESI (Reply 15):
So saving time on deboarding/boarding with two aisles may not really save much time on a turnaround.

Yes... but depending on the network/routing and scheduling profiles, one's turnaround policy, and operating in a non 24-hr infrastructure, that squeeze can make a difference... but then, a slight consequential delay can really screw it up if the non 24hr airport doesn't want to extend it's hours to cater for you because you had an earlier delay.

So, how much faster on a twin-aisle? Many factors come in play... one is how the boarding gate is set up too... if the airport has a common waiting room, and/or where the boarding pass check is done as you leave the gate to go to the aircraft, how fast the flowthrough can be achieved by the gate agents then becomes a factor... but that's expanding the scope of this topic too widely I think...   

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Stitch
Posted 2011-03-23 12:46:14 and read 13928 times.

Mr. Tsang did note his numbers were from airlines and not the OEMs. The FOCOM numbers are based on OEM configurations which may not reflect actual airline configurations. They are also based on LRC at optimum altitudes with zero reserve. Actual airline missions may not reflect all of these conditions.

As such, it strikes me as not outside the realm of possibility that with different assumptions plugged into the equation values, an airline's fuel burn numbers would not match those presented in mandala499's charts.

That should not automatically make Mr. Tsang's statements 'factual", since we don't know what airlines or missions he used as his reference points, but neither should that make them automatically suspect.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: LAXDESI
Posted 2011-03-23 12:53:43 and read 13891 times.

Quoting mandala499 (Reply 20):
Yes... but depending on the network/routing and scheduling profiles, one's turnaround policy, and operating in a non 24-hr infrastructure, that squeeze can make a difference... but then, a slight consequential delay can really screw it up if the non 24hr airport doesn't want to extend it's hours to cater for you because you had an earlier delay.

I am less and less optimistic about a twin aisle saving a lot of time in practice for most operators. I am more inclined to believe that 797 is likely to be a single aisle that spans the 175-225 seat market with transatlantic range for the 2 smaller models. A slightly wider single aisle 797 should be able to acheive 20% lower fuel burn and increase the range by nearly 20%.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: tsugambler
Posted 2011-03-23 12:59:42 and read 13840 times.

I still can't shake the feeling that we could see both a 737 re-engine AND a new twin-aisle light jet... or maybe even two new jets (a single-aisle and a twin-aisle) developed in tandem, a la the 757/767.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: mandala499
Posted 2011-03-23 13:11:00 and read 13810 times.

Quoting Stitch (Reply 21):
Mr. Tsang did note his numbers were from airlines and not the OEMs. The FOCOM numbers are based on OEM configurations which may not reflect actual airline configurations. They are also based on LRC at optimum altitudes with zero reserve. Actual airline missions may not reflect all of these conditions.

As such, it strikes me as not outside the realm of possibility that with different assumptions plugged into the equation values, an airline's fuel burn numbers would not match those presented in mandala499's charts.

That should not automatically make Mr. Tsang's statements 'factual", since we don't know what airlines or missions he used as his reference points, but neither should that make them automatically suspect.

And that is SPOT ON! Just because my numbers are factual, it does not mean that Mr. Tsang's numbers are not...

Quoting LAXDESI (Reply 22):
I am less and less optimistic about a twin aisle saving a lot of time in practice for most operators. I am more inclined to believe that 797 is likely to be a single aisle that spans the 175-225 seat market with transatlantic range for the 2 smaller models. A slightly wider single aisle 797 should be able to acheive 20% lower fuel burn and increase the range by nearly 20%.

Well, if we go to the 220 seat end... the 321's minimum turnaround is I think 30 mins using front and rear doors. So, that's 5 minute difference.
Now, if we have a 2-2-2 for 240 seats max capacity, that twin aisle does make a difference!
220 seat narrowbodies already have 1 weakness... LENGTH! To make it any faster, you need a wider aisle than the current "wide aisle" option offered by Airbus... (ignoring airport gate set up constraints)

Regardless of the 797 being a single aisle or a 2-2-2... what matters is... the fuel trip costs and non-fuel trip costs at the end of the day! As ridiculous/radical the idea of a 2-2-2 is, who knows... it could work and work well... (in the meantime, I'm looking forward to see an A321 NEO)...

Mandala499

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Stitch
Posted 2011-03-23 13:55:56 and read 14024 times.

I would not be at all surprised if Boeing and the engine OEMs are planning to adopt engines with larger fans and higher ByPass Ratios than the PW1100G and LEAP-X being planned for the A320neo (and a 737NGneo?).

So it might be that the fuel burn claims over the A320neo being bandied about are based primarily on this and perhaps a larger fuselage is either a "side-benefit" of using such engines or it might even be looking like such engines only will fit on a widebody design (due to clearance issues and perhaps undercarriage geometry).

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: davs5032
Posted 2011-03-23 14:08:34 and read 13924 times.

Quoting LAXDESI (Reply 15):
If your numbers are correct on total turnaround time(25 mins.) and deboarding/boarding(11 mins.), then the bottleneck is in other aspects of a turnaround and not necessarily in deboarding/boarding. So saving time on deboarding/boarding with two aisles may not really save much time on a turnaround.

I think there are enough factors that go into the turnaround time besides just boarding/deboarding, that the time saved would be too minimal to compensate for the additional weight/drag penalties seen with a wider fuselage. Any time saved during boarding/deboarding will have no value if Catering service and/or luggage cargo loading prevents the airline from taking advantage of the saved time.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: flipdewaf
Posted 2011-03-23 14:47:15 and read 14046 times.

Quoting Stitch (Reply 25):
So it might be that the fuel burn claims over the A320neo being bandied about are based primarily on this and perhaps a larger fuselage is either a "side-benefit" of using such engines or it might even be looking like such engines only will fit on a widebody design (due to clearance issues and perhaps undercarriage geometry).

Best reason I have heard yet for going twin isle.

Fred

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: SEPilot
Posted 2011-03-23 17:50:42 and read 13841 times.

Quoting tsugambler (Reply 23):
I still can't shake the feeling that we could see both a 737 re-engine AND a new twin-aisle light jet... or maybe even two new jets (a single-aisle and a twin-aisle) developed in tandem, a la the 757/767.

This will happen just as soon as Boeing engineers figure out how to work 36 hours a day. They have far too much on their plate right now to even think of it. Don't forget the 777, which is also endangered right now.

As to the twin aisle, there is one other factor that has received little mention, and that is cargo capacity. It will be substantially more, as less of the floor area is actually occupied by passengers, and hence it will have proportionally less baggage. This will give more space for revenue cargo, as well as being larger and able to carry containers.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: slowroll
Posted 2011-03-23 18:40:06 and read 13746 times.

Quoting parapente (Reply 17):
BTW the reason that sometimes getting off a plane is slow is when someone (say in the middle) is slow getting their bags out of the locker - there's always one.The issue is nobody can get past,thus backing up the queue.

The way airlines could speed up the turnaround on any jet is to have a deboarding video just like they have safety videos. Just before landing a video could play telling people how to efficiently exit the aircraft.

It could tell people:
have your bag out of the overhead bin BEFORE the line moves in front of you
if you are not exiting immediately remain seated until the aisle clears
if someone is seated and getting up, don't stand there and hold up the whole waiting for them to go
etc.

I bet it would actually be highly effective. Most passengers are simply clueless about how to do things efficiently.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Baroque
Posted 2011-03-23 23:59:22 and read 13563 times.

Quoting mandala499 (Reply 24):
And that is SPOT ON! Just because my numbers are factual, it does not mean that Mr. Tsang's numbers are not...

Well maybe quicksand is a bit harsh, but could you offer a mission and seating plans on which this would be the case?

Quoting TomB (Thread starter):
Airbus faces a bigger issue here than Boeing since the 737NG has a 5% fuel burn advantage versus the existing A320 family aircraft, from the data that I have seen from the airlines, not Boeing” David Tsang – the author in comment #2

If I can read your data aright, a trip of about 100 nm might come close.

Or am I not reading your graphs even close to correctly?

Another way to ask the question would be what on earth are airlines actually doing - as opposed to your assumptions - to alter/reverse your data to such an extent?

If the data you show gets close to real operational situations, then blithely bundling along on the assumption of a 5% fuel burn advantage for the 737NG might not be walking on quicksands, but sounds pretty close to trying to peddle a bicycle through the peat (gambut) of Central Kalimantan.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: StickShaker
Posted 2011-03-24 06:16:12 and read 13398 times.

The 738, 739, 752 and 753 are 39.5, 42.1, 47.3 and 54.5 meters in length respectively.
If there were no advantages in having twin aisles and wider fuselages then aircraft such as the 767 would never have been developed and single aisles would have continued to grow in length up to 80 meters or whatever was practical and aerodynamically plausible.
The threshold at which a twin aisle becomes more efficient than a single aisle seems to be somewhere around 180-200 seats. The 797 is described by Mike Bair as a sub 787 family rather than 737 replacement so comparisons with current LCC configurations may be misleading - its going to be a larger sized family than the 737.


Cheers,
StickShaker

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: seabosdca
Posted 2011-03-24 06:21:45 and read 13391 times.

Quoting StickShaker (Reply 31):
The threshold at which a twin aisle becomes more efficient than a single aisle seems to be somewhere around 180-200 seats.

Up to this point, that has not been true. For missions it can fly, the 753 absolutely kills the small widebody competition on efficiency. Its failure to sell more copies comes down to atrocious market timing, not a problem of design. The question is whether Boeing can find a way to build a small twin-aisle such that it is more competitive, compared to contemporary single-aisles (A321NEO), than the smallest widebodies (762, A310) have been historically.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: parapente
Posted 2011-03-24 06:28:34 and read 13382 times.

Slightly off subject I accept.But I wonder has anybody heard anything recently about the Blended winglet "scimitar" versions that API tested on a Jet Blue aircraft.With their track record and this being an even more refined design it is hard no to imagine that a 5% reduction in sfc is not a guarantee.

Having said this it is not I believe a straight "bolt on" a very small amount of structural work s required on the very outer portion of the wing. The retro 320 market is just "vast!" but also (note further improvements to the 2500 engine) recently.It will make new "standard" 320's alot more attractive as well.For those with shorter routes I would imagine that this might be a better option.

Sorry I appreciate that this post is not about the 737 replacement. However if API was to lunch thier A320 super winglet shortly it would certainly be a final nail in the "re work the 737 coffin" mind you from this thread and general Boeing comments I think that it is nailed down already!

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: enilria
Posted 2011-03-24 06:59:01 and read 13332 times.

Quoting TomB (Thread starter):
(per ASM?)

That's the trick. They are comparing a much bigger plane to the 737. Why don't they compare the 744 to the 737 on CASM? It's massively cheaper at the same seating density. They don't because it is irrelevant. Any comparison between different size aircraft is irrelevant. Larger aircraft have lower CASM. The 797 with the same seating as a 737 is going to be, at best, equal on fuel burn IMHO. The increased cross-section is going to eat up a ton of fuel. If you tell me that it is some amazing new aerodynamic technology that prevents that, then I'll tell you that the same amazing technology could be applied to a single aisle aircraft and achieve much better overall results.

Quoting cygnuschicago (Reply 3):
The turnaround time from a twin-aisle is a red-herring, especially in the US. There are too many delays in the system to get an extra leg in with quicker turnaround time.

There is still only one door and one jetway to exit from at 99.99% of U.S. airport gates.

Quoting AADC10 (Reply 9):
You have to take these number with a grain of salt. As shown by previous product launches, the numbers are driven more by the marketing department than engineering.

Then they mean nothing.

Quoting mandala499 (Reply 10):
However, most airlines would use 20-25 mins as the minimum time on the parking stand for a standard narrowbody on a full turnaround.

You can't have a hub structure with those kinds of turns. People and bags can't connect that fast. At the outstations the planes are mostly waiting for the next bank. There are exceptions where it is valuable, but they are fairly few. It's mostly useful to WN, but the plane is too big.

Quoting airfrnt (Reply 11):
I find it amusing that the OP is being attacked for quoting numbers at a aviation conference. AvB continues.

Never blame the messenger.  

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: tsugambler
Posted 2011-03-24 07:32:04 and read 13229 times.

Quoting enilria (Reply 34):
The increased cross-section is going to eat up a ton of fuel.

That's assuming that the cross-section will be circular, but most people who think that the 797 will be twin-aisle believe the fuselage cross-section will be somewhat elliptical, with drag comparable to current narrow-bodies.

Quoting SEPilot (Reply 28):
This will happen just as soon as Boeing engineers figure out how to work 36 hours a day. They have far too much on their plate right now to even think of it. Don't forget the 777, which is also endangered right now.

I acknowledge that developing two aircraft in tandem would be more work than developing one by itself, but I don't think it would be fully twice as much work... maybe 1-1/2 times as much. And Boeing doesn't have to make it work solely with the engineering resources they have--they could decide to hire more engineers, or (heaven forbid) outsource some of the engineering. Sure, it would be difficult, and it doesn't seem all that likely, but it's still completely plausible.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: mandala499
Posted 2011-03-24 08:43:49 and read 13162 times.

Quoting Baroque (Reply 30):
Well maybe quicksand is a bit harsh, but could you offer a mission and seating plans on which this would be the case?

Well, a 738 @ 189 seats vs A320 (CFM56-5B or V2500-A5) @180 seats for up to 500NM can provide such advantage... or 738 @189 seats vs A320 with CFM56-5A3s or V2500-A1s, if I remember correctly, the 5% or higher burn per seat advantage may exist up to about 750NM.

The A321 vs 739ER for max seat cap, or equal pax load, does give a consistent advantage to the 739ER from the performance numbers.

One can tweak the economic profiles to save a bit more, but allow the other to do the same, and the burn differences can be similar as the 250/280/0.78/LRC/0.78/280/250 profiles.

Quoting enilria (Reply 34):
Never blame the messenger.

Unfortunately, it is always easier to shoot the messenger. Heck, I almost did the same, until I re-read the OP's post...   

Quoting enilria (Reply 34):
You can't have a hub structure with those kinds of turns. People and bags can't connect that fast. At the outstations the planes are mostly waiting for the next bank. There are exceptions where it is valuable, but they are fairly few. It's mostly useful to WN, but the plane is too big.

It depends if one does a banked hub or a non-banked hub. On a banked hub, the shorter turnaround advantage applies at the outstation, and could be a useful flexibility on an inter-hub hop through 1 outstation... but on a single banked hub... not useful.
On a non-banked hub, the advantage could be used to the max.
For where I am, a banked hub is too expensive, and the infrastructure can't cope. A rolling or un-banked one is more effective... but then, I'm not sitting at the biggest market in the world!   

This twin-aisle idea I suspect is aimed at the 180-220 market. The 320NEO's FCOM2 numbers are already showing 17% reduction in fuel burn compared to the 320 (comparison on CFM to CFM option), whilst the marketing department is still touting 15% reduction. On the 321 vs 739ER, a 15% reduction would kill the 739ER's advantage in addition to the current payload-range disadvantage of the 739ER (which is key to 321's survival).


Mandala499

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: enilria
Posted 2011-03-24 09:04:08 and read 13073 times.

Quoting tsugambler (Reply 35):
Quoting enilria (Reply 34):
The increased cross-section is going to eat up a ton of fuel.

That's assuming that the cross-section will be circular, but most people who think that the 797 will be twin-aisle believe the fuselage cross-section will be somewhat elliptical, with drag comparable to current narrow-bodies.

Maybe I'm dumb, but I don't understand why a circle pushes more air out of the way than a larger ellipse. I would think aerodynamically it would have more to do with changing the shape of the nose to minimize the sharp impact of the nose to the air. That kind of change would be irrelevant to the cabin shape.

Quoting mandala499 (Reply 36):
It depends if one does a banked hub or a non-banked hub.

That is true. A hub like ATL can benefit, but most hubs can't handle being de-banked because they aren't large enough to sustain it.

Quoting mandala499 (Reply 36):
On a banked hub, the shorter turnaround advantage applies at the outstation

Not really. Let's say there is a Westbound bank at 12 noon and an Eastbound bank at 2pm and 4pm. Either the plane makes it back by 2pm or 4pm. There are a few occasions where now a flight that barely couldn't make it back to the 2pm bank can now just squeeze in, but in the vast majority of cases the plane still has to wait for the 4pm bank. That is a simplistic example, but each bank structure has what is known as a "pivot point" which is a geographical circle from the hub that the bank structure is built to optimally fit. Any city inside the pivot circle basically has their planes sit until the city on the pivot line returns. They can come back early, but then the plane pretty much sits at the hub instead. There are a few tricks to minimize that, but it is generally true.

Quoting mandala499 (Reply 36):
A rolling or un-banked one is more effective...

Only if the hub is gigantic or has a really large local market like EWR. A place like MEM or STL or even DEN has a hard time sustaining a rolling structure. WN is, of course, different, but even WN is moving toward banking.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: mandala499
Posted 2011-03-24 09:25:16 and read 13053 times.

Quoting enilria (Reply 37):
A hub like ATL can benefit, but most hubs can't handle being de-banked because they aren't large enough to sustain it.

There's more in this world than North America. I live in a place that is 16th in the world in terms of passenger numbers in 2010 and 47th in traffic movement in 2009. NONE of the airlines here do a banked hub. The peak time here is rolled mini-bank at best. Most do 30 mins turnarounds for the narrowbodies.
Just how large does one need to have a debanked hub depends on the market characteristics of the airlines banking there... and the catchment within the pivot area.

In the US, if you want to roll, it's a nightmare due to the volume! But, again, there's more to this world other than North America.

Quoting enilria (Reply 37):
Only if the hub is gigantic or has a really large local market like EWR. A place like MEM or STL or even DEN has a hard time sustaining a rolling structure. WN is, of course, different, but even WN is moving toward banking.

Yes, to an extent that is true. Outside North America, most hubs aren't as "crazily banked", because most of the hubs tend to be in places with adequate O&D market. It is in those places where shorter turnaround times MAY make a difference. For banked megahubs... the shorter turnarounds won't be a big advantage.

Mandala499

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: voltage
Posted 2011-03-24 09:26:54 and read 13025 times.

Quoting StickShaker (Reply 31):
The 738, 739, 752 and 753 are 39.5, 42.1, 47.3 and 54.5 meters in length respectively.
If there were no advantages in having twin aisles and wider fuselages then aircraft such as the 767 would never have been developed and single aisles would have continued to grow in length up to 80 meters or whatever was practical and aerodynamically plausible.

The reason that a shorter twin aisle becomes more efficient than a longer single aisle has to do with additional weight to make the fuse stiff enough, correct?

Quoting StickShaker (Reply 31):
The threshold at which a twin aisle becomes more efficient than a single aisle seems to be somewhere around 180-200 seats. The 797 is described by Mike Bair as a sub 787 family rather than 737 replacement so comparisons with current LCC configurations may be misleading - its going to be a larger sized family than the 737.

So if fuselage stiffness and structure is the important factor in determining whether to go twin aisle, how is that affected by moving to composites? I suspect the "threshold" you speak of will be different than it would be with aluminum planes.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: voltage
Posted 2011-03-24 09:32:09 and read 12996 times.

Quoting enilria (Reply 37):
Quoting tsugambler (Reply 35):
Quoting enilria (Reply 34):
The increased cross-section is going to eat up a ton of fuel.

That's assuming that the cross-section will be circular, but most people who think that the 797 will be twin-aisle believe the fuselage cross-section will be somewhat elliptical, with drag comparable to current narrow-bodies.

Maybe I'm dumb, but I don't understand why a circle pushes more air out of the way than a larger ellipse. I would think aerodynamically it would have more to do with changing the shape of the nose to minimize the sharp impact of the nose to the air. That kind of change would be irrelevant to the cabin shape.

I don't think he was saying that an elliptical twin-aisle crossection would have less drag than a circular single aisle. It would still have more drag, just not much more.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: rcair1
Posted 2011-03-24 09:53:44 and read 12948 times.

Quoting mandala499 (Reply 14):
The board/deboard process only itself (excluding stairs/headcount/cleaning, etc) can be done in 11 mins...

Really? I've never seen a NB loaded with all the carry on deplane in 5:30sec - much less board and stow all luggage. Heck - I've spent 5 minutes standing in the aisle. If you are at the back - it can easily be 10 minutes before you move.
Full NB's are hell to board/deboard these days.

Quoting slowroll (Reply 29):
It could tell people:
have your bag out of the overhead bin BEFORE the line moves in front of you

How? If you are sitting in a window or middle - you cannot get your bag out before the people between you and the aisle will move. To do this - every person AND their on-board luggage would have to fit in the aisle.
What about the lawsuits when passenger in 22A bonks passenger in 22C on the head with a 50 lbs rollaboard.

Quoting slowroll (Reply 29):
It could tell people:
if you are not exiting immediately remain seated until the aisle clears
if someone is seated and getting up, don't stand there and hold up the whole waiting for them to go
etc.

In your dreams - this will never fly. How 'good' are people about boarding in order - not. How often to people fasten seat belts, or put away electronics, or -fill in the blank-

Quoting slowroll (Reply 29):
I bet it would actually be highly effective. Most passengers are simply clueless about how to do things efficiently.

Yes - they are oblivions - oblivious to their surroundings. Telling them has little impact because they either "Know better" or "Don't listen"

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: mandala499
Posted 2011-03-24 11:07:49 and read 12881 times.

Quoting rcair1 (Reply 41):
Really? I've never seen a NB loaded with all the carry on deplane in 5:30sec - much less board and stow all luggage. Heck - I've spent 5 minutes standing in the aisle. If you are at the back - it can easily be 10 minutes before you move.

Well, 180 seats... if you use the aft and front doors with stairs... from the moment the plane is parked... it's about 2 minutes to position the pair of stairscases. From there, it's 4:30 - 5:00 to complete deboarding. Boarding takes about 6:00 - 10:00 to complete from the moment the first passengers enter the doors. On average it takes 10:00 from the moment the first pax enter the forward and aft doors to the time one closes the front door (the rear door is closed and stairs moved before the front door closes). Deboarding isn't the problem... boarding is! On a bad day, it takes forever!

25 minute turnarounds are doable on A320s with 180pax using front door only or front only. 733s with 148 seats can do it too. Mind you, we don't have winters here!    So, I don't see how twin-aisles would help unless we're talking about more than 190 seats in high density configuration.

Mandala499

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: JoeCanuck
Posted 2011-03-24 13:29:12 and read 12712 times.

People are generally pretty good at letting others by while they play with their carry on. There are often some who just won't get out of the way but most will scootch into the seat and clear the aisles.

I don't see how the minimal time saved would offset the extra expense of hauling around the extra aisle. Granted, any new narrow body will be larger than the 737...possibly wider than the 320...but we're talking another 18-20 inches plus the 8 required to even up with the 320.

I think fuel savings will be even more critical for airlines going forward than it is now...any extra, necessary burn will be avoided by airlines, regardless of passenger comfort, (which really doesn't seem to be a consideration anyway).

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: zvezda
Posted 2011-03-24 14:06:12 and read 12658 times.

Quoting SEPilot (Reply 28):
As to the twin aisle, there is one other factor that has received little mention, and that is cargo capacity. It will be substantially more, as less of the floor area is actually occupied by passengers, and hence it will have proportionally less baggage. This will give more space for revenue cargo, as well as being larger and able to carry containers.

If we assume a circular fuselage cross section, 2-2-2 has enough space to accommodate LD3s (single file). The ability to interline LD3s will be valuable for some customers.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: ADent
Posted 2011-03-24 14:34:31 and read 12561 times.

I would like to see these 25 minute turns in the US on airlines that charge for checked baggage and free carry ons.

I spent 45 in my seat loading up an A321 at Christmas time, and I wasn't in the 1st boarding group.

A 2-2-2 will definitely need center bins to speed up this overloaded bin scenario.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: nycdave
Posted 2011-03-24 15:09:57 and read 12476 times.

It'd also be great if at some point we could have dual-jetbridge boarding on either side of the aircraft.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: seabosdca
Posted 2011-03-24 15:22:45 and read 12439 times.

Quoting nycdave (Reply 46):
It'd also be great if at some point we could have dual-jetbridge boarding on either side of the aircraft.

That would take a lot more work than dual jetbridges on the same side, which should happen yesterday. With all the worry about turn times it is a bit of a surprise that they are not already more common in the US. In particular, I find it shocking that WN doesn't have them at every station.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: nycdave
Posted 2011-03-24 16:14:44 and read 12354 times.

Quoting seabosdca (Reply 47):
That would take a lot more work than dual jetbridges on the same side, which should happen yesterday. With all the worry about turn times it is a bit of a surprise that they are not already more common in the US. In particular, I find it shocking that WN doesn't have them at every station.

Very true. And I know opposite-side would be a huge hassle... but it WOULD totally eliminate crossover/doorway chokepoints.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: SEPilot
Posted 2011-03-24 17:04:01 and read 12290 times.

Quoting tsugambler (Reply 35):
And Boeing doesn't have to make it work solely with the engineering resources they have--they could decide to hire more engineers, or (heaven forbid) outsource some of the engineering.

They've been there and done that (and even have the T-shirt.) There are only so many qualified engineers, and they really need to be under Boeing's direct control. Losing engineering control was one of the big problems with the 787; they don't want to go down that road again.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: astuteman
Posted 2011-03-24 23:00:52 and read 12121 times.

Quoting TomB (Thread starter):
Airbus 320NEOversus A-320:

Fuel Burn Savings after Strengthening the Outer Wing Box 7%
Increase Price and Depreciation $ 6 Million per Aircraft?
Direct Operating Cost Savings (depends upon engine) 2-5%

7% fuel burn reduction is a bit different to..

Quoting mandala499 (Reply 36):
The 320NEO's FCOM2 numbers are already showing 17% reduction in fuel burn compared to the 320 (comparison on CFM to CFM option),

The 17% we're told is being quoted in the A320NEO FCOM would result in a nominal range of 3 500Nm for the A320/A321 NEO after allowing for the extra weight.

17% also seems comparable to the figures below

Quoting TomB (Thread starter):
Boeing New Light Twin Aisle Aircraft versus B-737NG:

Fuel Burn Savings (per ASM?) 15-20%
Airframe Maintenance Cost Savings 20-30%
Increase Price and Depreciation A Given
Cash Operating Cost Savings (per ASM?) 10-11%
Direct Operating Cost (with depn.) Savings “Significantly Lower”

Although of course ASM has now been introduced as another variable. I suppose on the basis that the A320 and 737 will to all intents and purposes be the same as before, that's understandable.

I'm intrigued that on the same day Boeing release figures showing a 2%-3% operating cost saving for the 737NEO and 10%-11% (on ASM) for the light twin, and then tell us they've still not decided what they're going to do.

I also wonder if the fact that Airbus operating documents predict a 17% fuel burn reduction for the NEO option, whilst Boeing are telling us that on the 737 NEO gives 11% - 12% savings points to a contributory factor in the decision making process...

Rgds

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: packsonflight
Posted 2011-03-24 23:33:49 and read 12052 times.

Sounds to me that Boeing wants to recycle engineering and manufacturing work from the 787 and create a kind of a 787 lite.

They know that with a new narrow body they would have to abandon the composite single barrel fuse, and go for a metal one, and that demands extra funding for R&D

So the 797 is the cheapest design they can get away with, for a new airframe, and now they are trying to sell the concept to the airlines but I can not see the interest there. Is any major airline exec on record saying: "this is the aircraft I want"

On the contrary, a lot of airline exec are on record urging Boeing to address the 737 problem, but nothing happens.....

In fact the Sonic Cruieser cathered more intrest with the airlines!

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Stitch
Posted 2011-03-25 00:10:03 and read 12016 times.

Quoting packsonflight (Reply 51):
They know that with a new narrow body they would have to abandon the composite single barrel fuse, and go for a metal one, and that demands extra funding for R&D

I see no reason why you could not build a narrowbody out of CFRP.

If they did stay with metal, that should actually reduce R&D spending since they have so many decades of experience there should be no surprises.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: BMI727
Posted 2011-03-25 00:23:42 and read 11980 times.

Quoting packsonflight (Reply 51):
Sounds to me that Boeing wants to recycle engineering and manufacturing work from the 787 and create a kind of a 787 lite.

You say that like it's a bad thing. Whatever Boeing does next will incorporate many of the technologies and lessons learned from the 787. Just like the 787 did with the 777 and so on. They'd be stupid not to. But, that said, simply creating a smaller 787 will not yield the type of results Boeing is looking for.

Quoting Stitch (Reply 52):
I see no reason why you could not build a narrowbody out of CFRP.

You certainly could. Whether it's worth it is something else. I would think that it is, but won't have as dramatic an effect as on larger planes.

Quoting packsonflight (Reply 51):
In fact the Sonic Cruieser cathered more intrest with the airlines!

All we've seen up to this point is vague references to this cross section and that cross section. Pretty much everything else is speculation and the only concepts we got to see are really advanced ones that are in all likelihood too far down the road to be the 737 replacement. We haven't seen a design fleshed out to the degree the Sonic Cruiser was nor have we really gotten any numbers other than things like wanting the range to be about the same as current narrowbodies. Airlines have probably gotten more than the public has, but you can't knock the current plans as generating less interest than the Sonic Cruiser simply because we haven't seen or heard of anything analogous yet in terms of a fairly well defined concept.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: packsonflight
Posted 2011-03-25 01:38:19 and read 11914 times.

Quoting Stitch (Reply 52):
I see no reason why you could not build a narrowbody out of CFRP.



It is simply not practical to do it because thinner walls of the narrow CFRP fuse create problems with impact resistance, and Boeing is publicly acknowledging this, so they are desperately trying to solve the 737 issue with a wide fuse.

The problem is that even though they can beat or match the economics of the 320NEO with this design, Airbus is bound to come up with a new gen narrow body with far superior economics later on.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: SEPilot
Posted 2011-03-25 04:48:11 and read 11798 times.

Quoting packsonflight (Reply 54):
The problem is that even though they can beat or match the economics of the 320NEO with this design, Airbus is bound to come up with a new gen narrow body with far superior economics later on.

This is by no means guaranteed. It is a risk, however; as we do not know what will become practical in the future; if we did, we could do it now. There may be no major breakthroughs; then again, there may be something that will make all we do today obsolete (although the chance of that is remote.) But Boeing has a decision to make this year, with billions of dollars and the future of the company for the next two decades at least on the line. I don't blame them for taking their time.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: JoeCanuck
Posted 2011-03-25 05:16:17 and read 11777 times.

There is more to CFRP than weight savings. In fact, weight is almost the least of the advantages. There can be cost savings, increase in durability, ease of repair, increase in service life, corrosion resistance, ease (relative to metal) in creating complex shapes...to name a few. It can also be cheaper and quicker to manufacture.

If the weight of CFRP is the same as metal, the other advantages can easily make it desirable as a construction material for Boeing's new narrow body.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: parapente
Posted 2011-03-25 05:16:47 and read 11772 times.

In a sense this twin aisle business is a red herring.They (Boeing) have said that it only works on a 200 - 250 seater (and above - fair enough).But we know that no LCC is interested in an aircraft capacity larger than 199 pax as after that you have to add another aircraft crew member thus destroying the economics.Even then most LCC,s are not optimised at even 199 - more like 160-180.

So since even Boeing recognises that double aisles don't make sense at this smaller size - and the discussion about the merit of 2 aisles is primarily speed of turnround (although not proven). The only operators that are really interested in this super fast turn round are in fact the LCC's the very people who would not be buying it in the first place!

Only a month ago a Boeing spokes person referred to the 757 market as "niche" yet here we are discussing it.I am really beginning to wonder about Boeings strategy and whether indeed they have one.

As for single aisle Airbus has said many times that with todays technology if they has to redesign the A320 it would end up looking like a ...A320.Well since Boeing keep telling anybody who will listen that their 737 is already 5% more efficient that the A320 how likley is it that they can produce something that is more efficient than the plane they have already got!

Zero I would have said. Just get on with it and re engine Boeing.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: JoeCanuck
Posted 2011-03-25 05:34:15 and read 11761 times.

Quoting parapente (Reply 57):
Only a month ago a Boeing spokes person referred to the 757 market as "niche" yet here we are discussing it.I am really beginning to wonder about Boeings strategy and whether indeed they have one.

Mike Bair has said that any new narrow body will focus on the 150-220 seat range and have a range and speed similar to the 737. To go ahead, they would need a 20% saving in fuel consumption and 10% overall savings.

He said they would only do one model line and probably offer a choice of two engines. Most of the talk of twin aisles has come from media. There isn't a lot of talk from Boeing execs about it.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: astuteman
Posted 2011-03-25 07:38:32 and read 11673 times.

Quoting JoeCanuck (Reply 58):
He said they would only do one model line and probably offer a choice of two engines. Most of the talk of twin aisles has come from media. There isn't a lot of talk from Boeing execs about it.

apart from the one quoted in the opening post of this thread of course, and which actually caused this thread to be created...  

Rgds

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: parapente
Posted 2011-03-25 08:32:29 and read 11578 times.

http://www.pprune.org/tech-log/44530...ater-optimized-flights-700-nm.html

Of course there is always another way.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: rcair1
Posted 2011-03-25 09:02:14 and read 11505 times.

Quoting mandala499 (Reply 42):
Well, 180 seats... if you use the aft and front doors with stairs

Okay - this is an obvious difference in our experiences. I almost never fly to places where we use stairs and board front/back. Nearly all (95%) of my flying is into places with jet bridges. Those few that do not use them, mostly use only one door. Experience colors perception.

Quoting mandala499 (Reply 42):
Mind you, we don't have winters here!

Ahhh yes.

Quoting ADent (Reply 45):
I would like to see these 25 minute turns in the US on airlines that charge for checked baggage and free carry ons.

Yep - that is where I'm at with this. I don't fly much anymore. As a consultant, my customers don't like to pay me to sit on a plane - so I work remotely now. But prior to a career change last year - I was 100K, but most of that was in/out of US or Northern Europe - with the occasional jaunt to Japan.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: tsugambler
Posted 2011-03-25 09:58:56 and read 11453 times.

Quoting SEPilot (Reply 49):
They've been there and done that (and even have the T-shirt.)

I want to see that T-shirt!

"My engineering job on the 787 was outsourced, and all I got was this lousy T-shirt!"   

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Stitch
Posted 2011-03-25 10:15:43 and read 11420 times.

Quoting packsonflight (Reply 54):
It is simply not practical to do it because thinner walls of the narrow CFRP fuse create problems with impact resistance, and Boeing is publicly acknowledging this, so they are desperately trying to solve the 737 issue with a wide fuse.

It's a quite simple matter to add additional layers of material around areas most subject to impacts to improve their resistance.

I sometimes wish Boeing would let the public whack away at a CFRP barrel section as they have let airline maintenance and fleet operations people do so the general public can see with their own eyes just how resilient the material is.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: packsonflight
Posted 2011-03-25 14:53:24 and read 11191 times.

Quoting Stitch (Reply 63):
It's a quite simple matter to add additional layers of material around areas most subject to impacts to improve their resistance.

Added layer is a added weight, and that is not acceptable when every kilo counts.

Boeing excec have publicly stated that alloy producers really did theyr homework since CFRP use picked up in the industry so why should Boeing use CFRP when new gen alloys are better suieted for a narrow fuse?

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: JoeCanuck
Posted 2011-03-25 15:04:39 and read 11176 times.

Quoting astuteman (Reply 59):
apart from the one quoted in the opening post of this thread of course, and which actually caused this thread to be created.

...which is why I said 'most', not all.

Quoting Stitch (Reply 63):

It's a quite simple matter to add additional layers of material around areas most subject to impacts to improve their resistance.

I sometimes wish Boeing would let the public whack away at a CFRP barrel section as they have let airline maintenance and fleet operations people do so the general public can see with their own eyes just how resilient the material is.

True...you don't have to make the whole fuse heavier...just the places likely to get ramp rash.

Quoting packsonflight (Reply 64):
Boeing excec have publicly stated that alloy producers really did theyr homework since CFRP use picked up in the industry so why should Boeing use CFRP when new gen alloys are better suieted for a narrow fuse?

They haven't said metal is better suited. They said that new alloys are better than they were. Boeing has not said what materials they would use for a new plane. There are advantages to both, regardless of weight.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: zvezda
Posted 2011-03-25 15:06:29 and read 11189 times.

Quoting packsonflight (Reply 64):
why should Boeing use CFRP when new gen alloys are better suieted for a narrow fuse?

I reject your premise that metal is better suited than CFRP for a fuselage. A CFRP fuselage requires far less MX than a metal fuselage. While metal alloys have improved, so have CFRP fibres and resins.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: astuteman
Posted 2011-03-25 15:12:58 and read 11188 times.

Quoting zvezda (Reply 66):
I reject your premise that metal is better suited than CFRP for a fuselage. A CFRP fuselage requires far less MX than a metal fuselage. While metal alloys have improved, so have CFRP fibres and resins.

And yet Boeing don't seem to have "rejected" it yet, for narrowbodys anyway. They haven't accepted it either, of course

Rgds

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: SEPilot
Posted 2011-03-25 15:57:32 and read 11110 times.

Quoting parapente (Reply 57):
As for single aisle Airbus has said many times that with todays technology if they has to redesign the A320 it would end up looking like a ...A320.Well since Boeing keep telling anybody who will listen that their 737 is already 5% more efficient that the A320 how likley is it that they can produce something that is more efficient than the plane they have already got!

What it comes down to is that Airbus does not see that they can get enough improvement from a clean sheet design to justify the expense. Boeing, however, has to do more to get to the same place, and hence the gap between a re-engine and a new design is smaller. It does appear that both could improve on the re-engine option with a new design; the question is how much, and how much it will cost.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: ha763
Posted 2011-03-25 22:50:53 and read 10898 times.

Quoting ADent (Reply 45):
I would like to see these 25 minute turns in the US on airlines that charge for checked baggage and free carry ons.

Well, HA does do 28 minute turns on interisland flights and they do charge for the first checked bag and have free carry ons. There is a lot of checked bags because of all the tourists. They also carry cargo like newspapers, fresh fish, and live fish that have to be unloaded and loaded from these flights.

Quoting packsonflight (Reply 54):
It is simply not practical to do it because thinner walls of the narrow CFRP fuse create problems with impact resistance, and Boeing is publicly acknowledging this, so they are desperately trying to solve the 737 issue with a wide fuse.

That is not what Boeing said. IIRC, what Boeing did say was that a narrow body CFRP fuselage would be thicker than the 787 since it would make it more able to withstand any ramp rash that would occur. Because of this the weight savings of CFRP would not be as great as is possible with a wide body aircraft. As mentioned before, Boeing has allowed the airlines to bash on a 787 fuselage piece with hammers to show them that equipment will not punch through the 'thin walls' of the 787 fuselage.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: tdscanuck
Posted 2011-03-26 10:53:45 and read 10728 times.

Quoting ha763 (Reply 69):
That is not what Boeing said. IIRC, what Boeing did say was that a narrow body CFRP fuselage would be thicker than the 787 since it would make it more able to withstand any ramp rash that would occur.

The 737 doesn't have any different ramp rash requirements than a 787. There is no reason for a 737 to have thicker skin than a 787. There's a minimum thickness for hail (and ramp rash), and if you get down to 737 sized Boeing was hinting that the structurally required thickness drops below the hail/ramp rash thickness, so you end up losing weight advantage.

Tom.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: morrisond
Posted 2011-03-26 15:33:48 and read 10534 times.

Quoting tdscanuck (Reply 70):
The 737 doesn't have any different ramp rash requirements than a 787. There is no reason for a 737 to have thicker skin than a 787. There's a minimum thickness for hail (and ramp rash), and if you get down to 737 sized Boeing was hinting that the structurally required thickness drops below the hail/ramp rash thickness, so you end up losing weight advantage.

That assumes that the cross section is circular, it seems like Boeing has discovered that they can use the extra strength to build an eliptical fuselage making 2x2x2 possible with little to no drag penalty over circular 3x3, and I would assume no weight penalty over a Metal 3x3 as CFRP should be a little lighter, but you add back in structure to make it eliptical so no weight penalty.

If the CFRP fuselage is no more expensive to build than metal and you get a 2x2x2 with no drag penalty or weight penalty vs Alloy 3x3 why wouldn't you build it and change the game?

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: tdscanuck
Posted 2011-03-26 21:08:09 and read 10420 times.

Quoting morrisond (Reply 71):
If the CFRP fuselage is no more expensive to build than metal and you get a 2x2x2 with no drag penalty or weight penalty vs Alloy 3x3 why wouldn't you build it and change the game?

Because, using the same technology, you can build a CFRP 3x3 that beats the pants off the competition.

Holding operating cost equal while improving some other feature is the business model of the Sonic Cruiser...airlines overwhelmingly told Boeing to take that technology and reduce operating cost.

Tom.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: BMI727
Posted 2011-03-26 22:17:43 and read 10353 times.

Quoting morrisond (Reply 71):
why wouldn't you build it and change the game?

Because it's a game nobody wants to play.

Quoting tdscanuck (Reply 72):
Because, using the same technology, you can build a CFRP 3x3 that beats the pants off the competition.

Holding operating cost equal while improving some other feature is the business model of the Sonic Cruiser...airlines overwhelmingly told Boeing to take that technology and reduce operating cost.

  

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: bestwestern
Posted 2011-03-26 22:26:34 and read 10341 times.

Quoting mandala499 (Reply 38):
. Most do 30 mins turnarounds for the narrowbodies.


You could shave 10 mins from a turn around on six daily segments (3 returns) - with no savings from first departure and last arrival of the day you could get one extra 1hr sector in assuming an earlier start and later finish- but the crew are out of place, and aircraft is now night stopping.

With the exception of the mega hub carriers - night stopping makes zero sense as the costs are huge and it is very inefficient use of crew. In Europe, for all but the mega majors, the vast majority of night stopping flights have vanished over the last few years.


[quote=ADent,reply=45]I would like to see these 25 minute turns in the US on airlines that charge for checked baggage and free carry ons.[/quote

In Europe - 25 mins is the norm for a low cost carrier that charges for hold baggage. US airlines need to stop people bringing the kitchen sink away on trips.

One of Europes largest airlines, easyJet, has stated that a wider single aisle makes more sense than a two aisle aircraft.

If the dual aisles are anything like the 777 with 3-4-3 that would be a disaster from a comfort perspective for those who like the aisle seat - these anorexic aisles are really bad.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-03-26 23:13:53 and read 10298 times.

Quoting tsugambler (Reply 35):
Quoting enilria (Reply 34):
The increased cross-section is going to eat up a ton of fuel.

That's assuming that the cross-section will be circular, but most people who think that the 797 will be twin-aisle believe the fuselage cross-section will be somewhat elliptical, with drag comparable to current narrow-bodies.

One area I can possibly help with. A circular cross-section will have a given frontal area. As far as I know an elliptical cross-section will have just about the same frontal area if it is say one foot wider, compensated for by being one foot lower. So an elliptical cross-section offering more width need not necessarily entail any frontal area penalty. Though whether the loss of that foot of height, on any given aeroplane, would throw up headroom or baggage-hold capacity problems, I'm not qualified to say.

I'm no engineer, but it appears obvious that an elliptical cross-section might need to be generally stronger in some key areas. But maybe that's less of a problem with composites?

One other possible 'dividend' - an elliptical fuselage would very probably generate some 'lifting body' benefit (i.e. lift generated by the fuselage), which might in turn allow the 797 designers to reduce the wing area? It doesn't seem to be widely known that the 'lifting body' concept has in the past (mostly when the space shuttle was being developed) been used to build some experimental aircraft that had no wings at all - but still flew OK!  http://en.wikipedia.org/wiki/Lifting_body

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: zvezda
Posted 2011-03-27 01:39:18 and read 10190 times.

I would not be too quick to write off the possibility of a circular 2-2-2 cross section. Compared to a flatter ovoid 2-2-2 cross section, a circular 2-2-2 cross section has two advantages:
1) the structural efficiency of being circular, and
2) the ability to carry LD3s.

The airlines which also operate widebodies, the ability to transship LD3s is valuable.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: morrisond
Posted 2011-03-27 05:05:38 and read 10104 times.

Quoting tdscanuck (Reply 72):
Because, using the same technology, you can build a CFRP 3x3 that beats the pants off the competition.

Holding operating cost equal while improving some other feature is the business model of the Sonic Cruiser...airlines overwhelmingly told Boeing to take that technology and reduce operating cost.

Tom.
Quoting BMI727 (Reply 73):
Because it's a game nobody wants to play.

Maybe I didn't explain it correctly.

If Boeing builds a 3x3 out of CFRP, because it needs to be thicker than optimal there is no weight savings over alloy, however at the same weight and drag you can make it eliptical and 2x2x2 with basically no penalty.

If this is true why not do it? It seems like from Boeing's statements that it is quite possible.

I can't remember who first suggested it but I also like the idea of one cockpit, and cross section along with two sets of wings and tails (if necessary) to cover the whole range from 150-250. One set of wings is optimised for short haul and another is wider, longer cord(giving a bigger cabin) for long range Transatl stuff, with a different sized tail if necessary. Common systems and cockpit commonality.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: flipdewaf
Posted 2011-03-27 06:42:12 and read 10025 times.

Quoting tsugambler (Reply 35):
And Boeing doesn't have to make it work solely with the engineering resources they have--they could decide to hire more engineers
Quoting morrisond (Reply 77):
If Boeing builds a 3x3 out of CFRP, because it needs to be thicker than optimal there is no weight savings over alloy, however at the same weight and drag you can make it eliptical and 2x2x2 with basically no penalty.

I see what you mean, if the ramp rash spec means that the skin thickness needs to be 4mm (these numbers are just for example and i have no idea if they are anywhere near real) and with an ovoid x section the bending moment required a skin thickness of 3.5mm and a circular x-section meant you needed 3mm of thickness for bending then there is no penalty as the bending is the "bottleneck" as it were.

I think what really limits the Ovoid X-section is that it has to be a surprising amount larger to work as people have stated on here. I may run some numbers later.

Quoting morrisond (Reply 77):
I can't remember who first suggested it but I also like the idea of one cockpit, and cross section along with two sets of wings and tails (if necessary) to cover the whole range from 150-250. One set of wings is optimised for short haul and another is wider, longer cord(giving a bigger cabin) for long range Transatl stuff, with a different sized tail if necessary. Common systems and cockpit commonality.

This has come up before but unfortunately aircraft aren't lego, integration of such things could make it difficult and perhaps quite innefficient due to lack of optimisation. Jack of all trades master of none.

Fred

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: zvezda
Posted 2011-03-27 07:36:41 and read 9983 times.

Quoting flipdewaf (Reply 78):
I see what you mean, if the ramp rash spec means that the skin thickness needs to be 4mm (these numbers are just for example and i have no idea if they are anywhere near real) and with an ovoid x section the bending moment required a skin thickness of 3.5mm and a circular x-section meant you needed 3mm of thickness for bending then there is no penalty as the bending is the "bottleneck" as it were.

Using the same fibres and resin used for the 787, the limiting factor would be impact resistance rather than flight loads. The answer to that is not simply to use more layers of the same fibres. The answer is to use different combinations of fibres and different resins, to optimize the CFRP for impact resistance. Airbus and Boeing are both funding research in impact resistant CFRP.

By the way, the CFRP fuselage of the 787 and A350 are much thicker than 4mm.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: JayinKitsap
Posted 2011-03-27 11:59:14 and read 9796 times.

Quoting zvezda (Reply 76):
I would not be too quick to write off the possibility of a circular 2-2-2 cross section. Compared to a flatter ovoid 2-2-2 cross section, a circular 2-2-2 cross section has two advantages:
1) the structural efficiency of being circular, and
2) the ability to carry LD3s.

The airlines which also operate widebodies, the ability to transship LD3s is valuable.

I think being able to use the LD3's would be huge, the 2-2-2 cross section also allows for a 3-3 with wider seats and single aisle so would satisfy a broader range of airlines.

There is very little difference in the thickness of CFRP fuse skin thickness vs diameter as the controlling structural parameter is spacing of ribs and the stiffeners. There is a big difference in the rib depth with respect to shell radius as the rib I value is so important.

Perhaps Boeing has realized they cannot replace the full range properly with a single aircraft as both size and aircraft range are in play. Right now the lower end has a lot of competition with the new entrants. Would it be possible that they would like about a 1/2 cycle to occur there so their lower end entrant has a significant tech and economic difference but not enough to force a new model from the competition. It did well with the 777 for a decade.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: packsonflight
Posted 2011-03-27 12:51:16 and read 9751 times.

Quoting morrisond (Reply 77):
If Boeing builds a 3x3 out of CFRP, because it needs to be thicker than optimal there is no weight savings over alloy, however at the same weight and drag you can make it eliptical and 2x2x2 with basically no penalty.

Where in hell did you get that from?

If true, they found a way to beat phisics, and that is inpressive.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-03-27 22:09:51 and read 9493 times.

Maybe the answer (to what Boeing is thinking about, anyway) is 'staring us in the face' from the excellent Jon Ostrower article on the Boeing patent that started this discussion.

The heading reads, 'WEIGHT-OPTIMISING INTERNALLY-PRESSURIZED COMPOSITE-BODY AIRCRAFT FUSELAGES HAVING NEAR-ELLIPTICAL CROSS SECTION.'

And lower down the text of the application reads, "This twin-aisle fuselage cross-sectional shape has also been shown to provide a perimeter-per-seat ratio comparable to that of a corresponding single-aisle, six-abreast, conventional aircraft fuselage having a circular or "blended circular arc" cross-section, and consequently, can also provide a cross-section-parasite-drag-per-seat ratio and an empty-weight-per-seat ratio that, in a first-order analysis, are comparable to those of the corresponding single-aisle fuselage cross-section, while offering better passenger comfort and owner revenue options."

Furthermore, at first sight the fuselage section at the top looks circular - but if you measure it, you'll find that it is indeed slightly wider than it's high. Maybe not a true ellipse, though, possibly just 'flattened at the top.' Additionally, I don't know much about freight containers, but is that an LD3 in the hold?

The seats are in 2-3-2 though. Possibly a lot depends on what sort of future the airlines are seeing in Premium Economy.' Maybe Boeing are looking at offering them 2-2 in Business, 2-2-2 in Premium Economy, 2-3-2 in cattle class?

http://www.flightglobal.com/blogs/fl...oeing-patent-may-provide-glim.html

[Edited 2011-03-27 22:19:16]

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: bestwestern
Posted 2011-03-27 22:11:19 and read 9493 times.

Thats an LD3-45.

Quoting zvezda (Reply 76):
The airlines which also operate widebodies, the ability to transship LD3s is valuable

Agree - but will the 2-2-2 have a hold height that would accept an LD3?

Are you thinking of an LD3-45 that Airbus use on their narrowbodies or a new size of LD? If the 767 (2-3-2) has trouble accepting standard LD3's side by side, how can a 2-2-2 do any better?

What ever happens - trans-shipment of anything smaller than an LD3 is really inefficient - I'm aware that you can put the smaller container into the LD3, but at a huge waste of space.

Firstly - look at an A300 cross section

http://upload.wikimedia.org/wikipedia/commons/thumb/e/e8/Airbus_A300_cross_section.jpg/800px-Airbus_A300_cross_section.jpg

and compare that to the boeing patent

http://www.flightglobal.com/blogs/flightblogger/737RSpatent_1000.jpg

and finally to the A320 cross section



From a laymans viewpoint - seems to be a poor use of cargo space in boeing patent and considering the aircraft is going to be shorter - will take a major cargo carrying hit - (A321 pax carrying capacity - A319 cargo capacity because of length and use of the LD3-45Ws)

[Edited 2011-03-27 22:37:58]

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: ADent
Posted 2011-03-27 23:35:07 and read 9401 times.

Quoting nycdave (Reply 46):
It'd also be great if at some point we could have dual-jetbridge boarding on either side of the aircraft.

UA was testing dual jet bridges at DIA (aka KDEN), mostly with A320 TED flights. It was nice on the flight I had since I am riff-raff and was near the back door.

If dual aisles are so great, how come these dual bridges are not more common?

Quoting ha763 (Reply 69):

Well, HA does do 28 minute turns on interisland flights and they do charge for the first checked bag and have free carry ons. There is a lot of checked bags because of all the tourists. They also carry cargo like newspapers, fresh fish, and live fish that have to be unloaded and loaded from these flights.

What's their secret? Are the bins not full (maybe people day tripping to another island w/o luggage)? Or are the other airlines not very good. WN's secret is less bags and no seat assignments.

Quoting bestwestern (Reply 74):
In Europe - 25 mins is the norm for a low cost carrier that charges for hold baggage. US airlines need to stop people bringing the kitchen sink away on trips.

Doesn't that airline limit passengers to 10KG carry on? My laptop bag weighs that much. How am I to get my roller board on too?  

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: zvezda
Posted 2011-03-27 23:36:12 and read 9410 times.

Quoting bestwestern (Reply 83):
Are you thinking of an LD3-45 that Airbus use on their narrowbodies or a new size of LD? If the 767 (2-3-2) has trouble accepting standard LD3's side by side, how can a 2-2-2 do any better?

In the graphic shown for the Boeing patent, standard LD3s can fit single-file. A 2-2-2 configuration could also fit standard LD3s single-file, as can a 767. Side-by-side LD3s requires a larger cross section, at least about as large as that of the A300/A310/A330/A340.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: bestwestern
Posted 2011-03-28 00:06:12 and read 9348 times.

Quoting ADent (Reply 84):
Doesn't that airline limit passengers to 10KG carry on?

No - easyJet, for example has a no weight limit - as long as it can be lifted - its OK.

Again looking at the photo of the new 737 bins - three bags into nine seats doesnt go - but neither do they on any narrowbody aircraft bin when the kitchen sink is brought onboard.

Quoting zvezda (Reply 85):
In the graphic shown for the Boeing patent, standard LD3s can fit single-file.

The graphic shows a LD3-45w

Look at the A300 graphic - LD3s only have one cutaway side.

Perhaps I'm wrong, but I dont think the narrowide will be tall enough for an LD3.

And for container sizes:

LD3


LD3-45W

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Stitch
Posted 2011-03-28 00:07:23 and read 9353 times.

Depending on how high she sits off the ground, you might be able to bulk-load. Maybe with that optional telescoping loader the 757-200 family offered.

They could also maybe use LD2s side-by-side like on the 767.

[Edited 2011-03-28 00:08:23]

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: bestwestern
Posted 2011-03-28 00:24:51 and read 9336 times.

Quoting Stitch (Reply 87):
They could also maybe use LD2s side-by-side like on the 767.

The patent image clearly shows one container.

With the LD2 only used on the 767 - would this hamper the sale of the aircraft in China, a market with only 6 767s flying?

The LD2 is sized as follows

Quoting Stitch (Reply 87):
you might be able to bulk-load


Would Bulk loading not drive up turnaround times?

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: zvezda
Posted 2011-03-28 00:27:18 and read 9341 times.

Quoting bestwestern (Reply 86):
The graphic shows a LD3-45w

Negative. The graphic shows a cargo hold height of 64" and a base width of 62". If you don't want to measure it, the clearest clue that it's not an LD3-45w is that the sloping sides of an LD3 go about half way up from the base, but those of an LD3-45w go only about a third of the way up from the base.

Quoting Stitch (Reply 87):
They could also maybe use LD2s side-by-side like on the 767.

Side-by-side LD2s would not fit in a reasonably sized 2-2-2 aircraft. Single-file LD3s are already a tight fit. If you make the fuselage big enough to accommodate side-by-side LD2s, then you'll have space for 2-3-2.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: bestwestern
Posted 2011-03-28 00:35:29 and read 9318 times.

Quoting zvezda (Reply 89):
the sloping sides of an LD3 go about half way up from the base,

Following your logic - Which LD3's have two sloping sides then?


More importantly - what does the graphic tell us about the width of the seats and aisles?

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: zvezda
Posted 2011-03-28 00:55:04 and read 9308 times.

Quoting bestwestern (Reply 90):
Following your logic - Which LD3's have two sloping sides then?

That is not following my logic -- or any logic. Think about it. Suppose, for the sake of the discussion, Boeing (or anyone) were to build an aircraft to accommodate single-file LD3s. Note that optimal use of space would dictate that the base area be centered along the centreline of the aircraft. Would Boeing build an asymmetric cargo hold, forcing either a left or right orientation of LD3s? No, of course not. The cargo hold would be symmetric, allowing LD3s to be loaded alternating left/right for balance or loading convenience. This would also allow for the possibility of a future ULD with two sloping sides to fill the whole space (depicted in the graphic).

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Stitch
Posted 2011-03-28 09:35:21 and read 9097 times.

Quoting bestwestern (Reply 88):
With the LD2 only used on the 767 - would this hamper the sale of the aircraft in China, a market with only 6 767s flying?

I don't see why not. Interlining containers from narrowbodies to widebodies doesn't happen now (since an A320 family aircraft cannot take an LD3 due to insufficient hold height) . So they can use the LD2s solely with the "797" and move the contents to/from LD3s for their widebodies.

Quoting zvezda (Reply 89):
Side-by-side LD2s would not fit in a reasonably sized 2-2-2 aircraft. Single-file LD3s are already a tight fit. If you make the fuselage big enough to accommodate side-by-side LD2s, then you'll have space for 2-3-2.

If Boeing goes twin-aisle, I do not believe they will limit it to 2+2+2, but instead will allow for 2+3+2 using 17" seat cushion width.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: tdscanuck
Posted 2011-03-28 09:54:29 and read 9071 times.

Quoting packsonflight (Reply 81):
Where in hell did you get that from?

If true, they found a way to beat phisics, and that is inpressive.

No, it's not beating physics. The point was that if your minimum skin thickness is dictated by impact resistance, then you're carrying extra material than you need for structural loads. That means you can increase structural loads (e.g. by going to an off-nominal cross-section) with no weight penalty *above what you've already paid for the skin thickness*. It's "free" structural margin that you can "spend" on doing different things to the cross-section.

Quoting ADent (Reply 84):
If dual aisles are so great, how come these dual bridges are not more common?

Jetbridges are far less of a choke point than aisles...nobody is trying to load luggage in a jetbridge.

Tom.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: flipdewaf
Posted 2011-03-28 10:50:16 and read 8950 times.

Quoting tdscanuck (Reply 93):
Jetbridges are far less of a choke point than aisles...nobody is trying to load luggage in a jetbridge.

Tom.

Yes but a second jet bridge would act almost the same for boarding/deboarding as a second isle, i.e. two routes in/out when a fatty or a member of the tiverton west angling team with a huge "carry on" that can't be carried gets in the way.

Fred

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: packsonflight
Posted 2011-03-28 12:08:58 and read 8846 times.

Quoting tdscanuck (Reply 93):
No, it's not beating physics. The point was that if your minimum skin thickness is dictated by impact resistance, then you're carrying extra material than you need for structural loads. That means you can increase structural loads (e.g. by going to an off-nominal cross-section) with no weight penalty *above what you've already paid for the skin thickness*. It's "free" structural margin that you can "spend" on doing different things to the cross-section.

You could argue that there is no weight penalty compered to narrow CFRP, but then you run the risk that your competitor builds a narrow alloy fuse, and then you suddenly your weight penalty is exposed.

Another problem with wide fuse is that eaven though you save 10 minutes in turnaround time, the savings are quickly absorbed in increased burn, (due to much higher parasite drag) when flying time exceeds lets say 2 hrs. This becomes eaven bigger issue with higher fuel prices.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-03-28 17:44:22 and read 8638 times.

Quoting packsonflight (Reply 95):
Another problem with wide fuse is that eaven though you save 10 minutes in turnaround time, the savings are quickly absorbed in increased burn, (due to much higher parasite drag)

According to Boeing's patent, packsonflight, not if, by using composites, you are able to make the fuselage elliptical- that is, lower as well as wider - thus keeping frontal area down.

"This twin-aisle fuselage cross-sectional shape has also been shown to provide a perimeter-per-seat ratio comparable to that of a corresponding single-aisle, six-abreast, conventional aircraft fuselage having a circular or "blended circular arc" cross-section, and consequently, can also provide a cross-section-parasite-drag-per-seat ratio and an empty-weight-per-seat ratio that, in a first-order analysis, are comparable to those of the corresponding single-aisle fuselage cross-section."

Please see Post 82 above for further explanation and a link to the Boeing application.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: TomB
Posted 2011-03-29 03:26:15 and read 8427 times.

To paraphrase Patent Application US 2010/0200697 A1, on a fuselage with a "near elliptical" cross section (a wide oval fuselage), every square inch of the fuselage surface is subject to different critical design loads. These design loads include pressurization induced loads and fuselage bending and torsional loads.

To achieve an optimized lightweight fuselage structure, Boeing proposes to find the optimum combination of composite materials for each square inch of the fuselage surface by varying:
- Thickness of the fuselage skin
- Depth of the fuselage frames
- Thickness and width of the frame flanges
- Angular orientation of the composite plies
- Local strengthening with metal or carbon fiber materials
- The addition of foam sheets or honeycomb material to stiffen the fuselage skin

Hey Boeing, do you realize you have a minor mistake in your patent application. Look at Page 7, line 10.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-03-31 06:53:58 and read 7943 times.

Quoting TomB (Reply 97):
To achieve an optimized lightweight fuselage structure, Boeing proposes to find the optimum combination of composite materials for each square inch of the fuselage.

Just about sure that you're right, TomB.

And almost as sure that they'll succeed. I expect that I'll get 'crucified' for saying it, but the trend that has become increasingly clear in recent years is, "Boeing innovate, Airbus (much later) emulate......."

[Edited 2011-03-31 06:57:25]

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: packsonflight
Posted 2011-03-31 07:23:40 and read 7896 times.

Quoting NAV20 (Reply 98):
And almost as sure that they'll succeed. I expect that I'll get 'crucified' for saying it, but the trend that has become increasingly clear in recent years is, "Boeing innovate, Airbus (much later) emulate......."



Please provide us with some examples of what has become so increasingly clear.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-03-31 07:27:25 and read 7888 times.

Quoting packsonflight (Reply 99):
Please provide us with some examples

777, 787.........? Airbus hasn't produced anything at all that competes?

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: astuteman
Posted 2011-03-31 07:32:04 and read 7865 times.

Quoting NAV20 (Reply 98):
but the trend that has become increasingly clear in recent years is, "Boeing innovate, Airbus (much later) emulate......."
Quoting NAV20 (Reply 98):
I expect that I'll get 'crucified' for saying it

Rightly so   

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: flipdewaf
Posted 2011-03-31 07:52:54 and read 7860 times.

Quoting NAV20 (Reply 98):
"Boeing innovate, Airbus (much later) emulate......."

Yeah like the wide body twin, fly-by-wire technology, composite structures, flight deck commonality......oh no that's wrong.

Fred

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-03-31 08:09:06 and read 7841 times.

Quoting flipdewaf (Reply 102):
Yeah like the wide body twin, fly-by-wire technology, composite structures,

In fairness, flip, I was careful to say 'In recent years.' Quite happy to agree that Airbus took Boeing by surprise with things like the A300 - the birth of ETOPS.

But the modern-day question is - how can Airbus 'answer' the 777, the 787, and the 'looming' 797'? With even the A350 (already a compromise at best, one aeroplane competing with two, and at least two years from first delivery, probably more)?

Just at the moment, I know which of the two firms I'd prefer to be working for........

[Edited 2011-03-31 08:10:37]

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: flipdewaf
Posted 2011-03-31 08:46:21 and read 7793 times.

Quoting NAV20 (Reply 103):
But the modern-day question is - how can Airbus 'answer' the 777, the 787, and the 'looming' 797'? With even the A350 (already a compromise at best, one aeroplane competing with two, and at least two years from first delivery, probably more)?

Well I think that your devotion to Boeing is admirable but there is again a slight bit of bias to what you say.

There are two ways to do this, first is the way that involves logic.

The A350 is a compromise but what plane isn't? It will do just fine against the T7. Infact I'd say it'll do to the T7 what the 787 is about to do the the A330. At the lower end of the spectrum Boeing and Airbus will likely continue to battle it out at 50:50 with maybe a 10% swing either way.

Second is turning it the other way countering what you say.

What will Boeing do to try and counter the A350, they'll never get 20% operating costs out of that nearly 20 year old frame and the 787 going to be at least another 3 years befor it enters service the A330 improvements will mean it will only be able to compete over 7850nm. The 797 or whatever they want to call it will never happen because Boeing need to spend at least 15bn to get better then the A320NEO which is only going to cost Airbus 1bn.

I know who I'd rather be working for....

So nav stop spouting fanboy nonsense, it makes discussions on here look stupid and does nothing to you credibility, those with a modacome of understanding are not fooled.

Fred

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-03-31 09:12:40 and read 7741 times.

Quoting flipdewaf (Reply 104):
So nav stop spouting fanboy nonsense

Since I come from a De Havilland family, flipdewaf - including ageing uncles who hand-built Mosquitos in their time - I guess that I'm the ultimate 'loser' in the aviation field, whatever happens from here.....  

But I stand by what I said. As things stand, Boeing appear still to be about designing better aeroplanes.

I honestly can't fathom what Airbus are about at the moment. All I CAN be sure of is that it has little if anything to do with aeroplanes - and a lot more to do with politics.

It's your privilege to disagree..... "No hard feelings....."  

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: pylon101
Posted 2011-03-31 09:21:32 and read 7728 times.

Quoting NAV20 (Reply 103):
Just at the moment, I know which of the two firms I'd prefer to be working for........

I would strongly advise to become an employee of Airbus. Due to social security reasons.
U.S. business ethics is based on: shareholders - Board of Director: they - and they only - are the company.
Employees are supposed to comply with "easy come - easy go" principle.

The most amazing thing is that this principle is applied to virtually everything.
I am an employee of a non-profit company - but attitudes are the same.

P.S. Obviously you question was within a.netters' everyday A-B discussion "flight envelope".
So I am trying to go beyond the tense and quite boring 737NG vs. 320OEO/NEO talk.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Baroque
Posted 2011-03-31 09:50:29 and read 7691 times.

Quoting astuteman (Reply 101):
Quoting NAV20 (Reply 98):
but the trend that has become increasingly clear in recent years is, "Boeing innovate, Airbus (much later) emulate......."
Quoting NAV20 (Reply 98):
I expect that I'll get 'crucified' for saying it

Rightly so

Two pounds of nails on their way.    Let me know if you will need a javelin - no cannot use a Javelin they were built by Gloster.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-03-31 09:51:10 and read 7695 times.

Quoting pylon101 (Reply 106):
I would strongly advise to become an employee of Airbus. Due to social security reasons.
U.S. business ethics is based on: shareholders - Board of Director: they - and they only - are the company.
Employees are supposed to comply with "easy come - easy go" principle.

The most amazing thing is that this principle is applied to virtually everything.
I am an employee of a non-profit company - but attitudes are the same.
Very interesting comment, pylon101. As far as I can see, you're arguing that company directors are not entitled to 'direct.' The question is - if they're not there to 'direct' the company, what the hell ELSE are they there for?

My own view is that it's a 'balance of forces.' The Board has its say, but so do the directors, and also the workforce. Most times, a compromise is achieved by which the company survives.

Maybe not the 'best' system. But arguably better than any of the alternatves..........  

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-03-31 10:02:54 and read 7666 times.

Quoting Baroque (Reply 107):
Let me know if you will need a javelin - no cannot use a Javelin they were built by Gloster.

Guess I'd settle for a Mark-Three Lee-Enfield, Baroque........

Like father, like son.......all the way from 1918 to 1958.........from defeating Germany in WW1 to defending it after WW2. With EXACTLY the same rifle. Funny old world, I guess........  

[Edited 2011-03-31 10:07:14]

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: zvezda
Posted 2011-03-31 12:33:45 and read 7555 times.

Quoting NAV20 (Reply 98):
I expect that I'll get 'crucified' for saying it, but the trend that has become increasingly clear in recent years is, "Boeing innovate, Airbus (much later) emulate......."

I can think of three innovations first applied to commercial aircraft in this century by Airbus:
- electro-hydrostatic actuators
- LED lighting
- brake-to-vacate

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-04-01 06:00:40 and read 7361 times.

Quoting zvezda (Reply 110):
I can think of three innovations first applied to commercial aircraft in this century by Airbus

Sure, zvesda, but there's a 'question of degree.'

Boeing (always presuming that the 787 makes it into service and succeeds) pioneered the use of composites instead of aluminium. A change which may prove to be every bit as significant as the 1920s switch from fabric covering to stressed-skin aluminium. Airbus took the view that the change was 'unnecessary'; but had eventually to concede that the idea 'had legs,' and hurriedly opt for the A350.

Now Boeing appear to be planning to 'build on' their achievement by producing an aeroplane with an elliptical fuselage - allowing larger passenger loads with no corresponding increase in frontal area. Airbus appears to be taking the view that all they need to do to compete is re-engine the A320.

There was a time when Airbus were the innovators - the A300 and its derivatives just about 'created' the whole concept of ETOPS, and producing the A320 (a worthy competitor to the 737) from a 'standing start' was also a tremendous achievement.

But my feeling is that the situation has turned around. Boeing have a range that spans everything from the 737 through the 787, the 772, and the 773 to the 748. They are clearly now planning that the 797 will fill the gap between the 737 and the 787. Meanwhile, Airbus are still stuck with just three basic models - A320, A330, and A380. Even if they eventually succeed with the A350, in a few years' time, they STILL won't have anything like the product range that Boeing already has; even if the 797 doesn't work out.

And they'll always be 'playing catch-up' from a disadvantaged position - since Boeing has patented both monolithic composite construction (in the 787) and now elliptical composite fuselage cross-sections (in what looks like becoming the 797).

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Baroque
Posted 2011-04-01 06:17:32 and read 7347 times.

Quoting NAV20 (Reply 111):
Boeing have a range that spans everything from the 737 through the 787, the 772, and the 773 to the 748.

"Have". Could that be "will have" or "might have" or "should have"???? Unless the 787 entered service overnight without announcement.

Playing "catch-up" from the Airbus position is something I think I could cope with. At least they have a functioning production line for the A330!

And shock horror, panels might just work you know. Even worse, suppose they are more easily scaled than barrels, there is an awful thought. But it could not be, cos Airbus are just so inexperienced and ignorant about composites.  

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: zvezda
Posted 2011-04-01 06:40:02 and read 7306 times.

Quoting NAV20 (Reply 111):
Sure, zvesda (sic), but there's a 'question of degree.'

Boeing (always presuming that the 787 makes it into service and succeeds) pioneered the use of composites instead of aluminium. A change which may prove to be every bit as significant as the 1920s switch from fabric covering to stressed-skin aluminium.

I'll concede that Airbus have recently been less innovative than Airbus were previously. I'll also concede that the 787's fuselage construction may turn out to be as important as the switch from wood and fabric to metal fuselages and the switch to jet engines. However, what you wrote was:

Quoting NAV20 (Reply 98):
Boeing innovate, Airbus (much later) emulate.......

That's just not correct. Both companies innovate and both companies emulate. The proportions shift somewhat from time to time, but to paint one company as a technology leader and the other as a follower is simply incorrect. You were doing much better when you acknowledged that it's a 'question of degree.'

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Carls
Posted 2011-04-01 06:57:47 and read 7287 times.

Quoting LAXDESI (Reply 2):
797 that is being proposed has to be a 2-2-2 layout

2+2+2 is not going to work. It must be at least 2+3+2 so you are increasing capacity over 3+3, otherwise you will be waisting space in just another isle.

I really think Boeing will do a 737 NEO and try to fight against Airbus, BB and Embraer. Technology is not mature enough to get a true new light jet that save enough money that the investment is justified.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: rheinwaldner
Posted 2011-04-01 07:20:31 and read 7268 times.

Quoting NAV20 (Reply 98):
I expect that I'll get 'crucified' for saying it

Ok, you asked for it:

Quoting NAV20 (Reply 111):
Boeing have a range that spans everything from the 737 through the 787, the 772, and the 773 to the 748.

First this range is smaller than A318 to A380.

And over the last 4 years the following Airbus aircraft families outsold the comparable Boeing aircraft family:
- A320 outsold the 737NG
- The A330 outsold the 787
- The A380 outsold the 748

So I don't say that Boeing obiously has a range of losers but you surely have to bury your claims.

Quoting NAV20 (Reply 111):
They are clearly now planning that the 797 will fill the gap between the 737 and the 787.

If the 797 will emerge the way you think Boeing's product range would roughly shrink to half of the size-range covered by Airbus (Boeing: 180 to 420 seats, Airbus 130 seats to 530 seats).

Quoting NAV20 (Reply 111):
they STILL won't have anything like the product range that Boeing already has

No, Boeing would give up big chunks of those markets that they have served in the past...

Quoting NAV20 (Reply 111):
now elliptical composite fuselage cross-sections (in what looks like becoming the 797).

Bringing an elliptical NB fuselage to get a two aisles would give Airbus a significant advantage to damage Boeing's relevance even more.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: seabosdca
Posted 2011-04-01 07:23:20 and read 7264 times.

Quoting NAV20 (Reply 111):
Boeing (always presuming that the 787 makes it into service and succeeds) pioneered the use of composites instead of aluminium.

For the fuselage, only. Airbus had the first composite vertical stabilizer (A300), secondary wing structure (A330/A340), and wing box (A380). I'd say Boeing couldn't have done it without Airbus, any more than Airbus could have built an A320 without drawing heavily on existing Boeing inventions.

Quoting NAV20 (Reply 111):
Boeing have a range that spans everything from the 737 through the 787, the 772, and the 773 to the 748. They are clearly now planning that the 797 will fill the gap between the 737 and the 787. Meanwhile, Airbus are still stuck with just three basic models - A320, A330, and A380.

You can't give Boeing credit for a 797 that is still undefined and un-launched while not giving Airbus credit for the A350 -- the prototype of which is already under construction.

Both manufacturers' lineups have their strengths and weaknesses. Boeing will have to spend a lot of money to counter the A320 NEO, which won't cost nearly as much. Airbus pretty much gave up on the midsize widebody market, conceding it to the 787, by giving the A350 its huge wing -- but then again, once there is a scaled-up engine, that will pay huge dividends on the top end and will put the 77W out of business unless Boeing, again, spends money.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-04-01 07:31:18 and read 7250 times.

Sorry about the missing 'z', mate, not a key I often use!  
Quoting zvezda (Reply 113):
I'll concede that Airbus have recently been less innovative than Airbus were previously.

Then I guess we're in entire agreement. Since what I posted was:-

Quoting NAV20 (Reply 98):
the trend that has become increasingly clear in recent years is, "Boeing innovate, Airbus (much later) emulate......."

Please note the phrase 'in recent years'.........

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: frmrCapCadet
Posted 2011-04-01 07:43:59 and read 7229 times.

Quoting NAV20 (Reply 111):
d they'll always be 'playing catch-up' from a disadvantaged position - since Boeing has patented both monolithic composite construction (in the 787) and now elliptical composite fuselage cross-sections (in what looks like becoming the 797).

Did Boeing patent the monolithic composite hull, or just one particular way of doing it? The later is what I suspect, and what classically can get a patent. The former is just an idea.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-04-01 07:54:14 and read 7219 times.

Quoting frmrCapCadet (Reply 118):
Did Boeing patent the monolithic composite hull, or just one particular way of doing it?

Wondered myself about that, frmrCapCadet. Thought off-hand, early on, that it would be unlikely to 'stick.' But - given that Airbus have had to use panels rather than monocoque for the A350 (vastly complicating the problem of lightning protection) - I can only presume that, for the moment, the Boeing patent has indeed 'arrived' for the time being.

[Edited 2011-04-01 08:29:16]

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: brindabella
Posted 2011-04-01 07:56:03 and read 7220 times.

Quoting NAV20 (Reply 103):
But the modern-day question is - how can Airbus 'answer' the 777, the 787, and the 'looming' 797'? With even the A350 (already a compromise at best, one aeroplane competing with two, and at least two years from first delivery, probably more)?

Just at the moment, I know which of the two firms I'd prefer to be working for........


My conviction remains that B has a minimum lead of 2 years in CFRP construction technology, which would generally incline me to the same preference.

So far so good, as you might say.

In addition ...

Quoting flipdewaf (Reply 104):
What will Boeing do to try and counter the A350, they'll never get 20% operating costs out of that nearly 20 year old frame and the 787 going to be at least another 3 years befor it enters service the A330 improvements will mean it will only be able to compete over 7850nm. The 797 or whatever they want to call it will never happen because Boeing need to spend at least 15bn to get better then the A320NEO which is only going to cost Airbus 1bn.

I know who I'd rather be working for....



Sorry, Fred, you totally over-egged it there. You didn't even lay a glove on him.

Game over?

No, not necessarily ...

The A320neo decision has now forced B into the B797 decision which I strongly suspect is extremely unwelcome. It appears that it has only been taken because the B737 family, being one of their two major "profit centres", has suddenly come under threat. Does anybody doubt that B would have been far happier with the status quo pertaining say 18 months ago?
At that stage B were justified in anticipating that the happy and profitable A320/B737 duopoly would be continuing for many years to come (or at least that is what anyone would think when reading the salvoes being loosed here on A-Net on any mention of the GTF or the C-series. According to the apparent consensus of the time, Bombardier had no chance whatsoever, and as for poor old Pratts ... well, sad, really! My, how things change!).


Back to the topic:
The technology lead that has been apparent since the B787 launch (now much reduced, it must be said!), should have seen B controlling the contest for some time to come, rather than being forced to react already.
Definitely a bad look for B.

And, even worse for B ...

If the recent thread about the A351 being up-gauged to aim directly at the B77W is in fact based on reality, then over time, the other B "profit centre" will also come under severe, and ultimately, fatal threat.
And this just when B appear to have committed to the B797 decision (probably not a coincidence, hmmm?) ...

If the A351 development is true, then it is potentially a brilliant move by A, (on condition the up-gauged A351 can be made to work - and I wouldn't be betting against it!).
Again, a bad look for B.

In short, B will have to react again - if they have any resources left(!).




Maybe working for A would be cool, also!

Billy
    

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: seabosdca
Posted 2011-04-01 08:01:10 and read 7210 times.

Quoting brindabella (Reply 120):
on condition the up-gauged A351 can be made to work

It's all dependent on how much thrust they can get out of the engine makers. That wing, especially with the extension planned for the current -1000, will take them as far as they want to go.

There is a lot of hyperbole here. To read these comments, you would think that one manufacturer is about to put the other out of business. Not so.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: tsugambler
Posted 2011-04-01 08:11:46 and read 7190 times.

Quoting seabosdca (Reply 121):
There is a lot of hyperbole here. To read these comments, you would think that one manufacturer is about to put the other out of business. Not so.

Hyperbole? HERE??? Surely you jest! Ah--but it is April Fool's Day...

Seriously, all the talk of how one manufacturer or the other is totally screwed is getting ridiculous. Neither is going to box the other into a corner any time soon.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: pylon101
Posted 2011-04-01 08:31:54 and read 7166 times.

Quoting tsugambler (Reply 122):
Seriously, all the talk of how one manufacturer or the other is totally screwed is getting ridiculous

It reminds me of a popular anecdote about The Bolshoi Ballet:

- You are a ballet dancer at Bolshoi. Is it true that ballet dancers wish their rivals to fall and get wounded?
- Wounded, you are saying? No. No way - Death. Only death.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: frmrCapCadet
Posted 2011-04-01 10:08:39 and read 7071 times.

Quoting Carls (Reply 114):
+2+2 is not going to work. It must be at least 2+3+2 so you are increasing capacity over 3+3, otherwise you will be waisting space in just another isle.

The speculation on a-net on the part of several of us is based on statements that Boeing in any event was going to try to match the wider seats of the 320, likely as a matter of matching comfort. Getting rid of the dreaded middle seats even staying with the 17 inch seats and adding a second 18 inch aisle instead of going to a 24 inch aisle would enable all seats to be aisle or window with relatively little increase in hull diameter needed. In addition several have pointed out that this "narrow" wide body would be able to deal with container bins in the lower section.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: brindabella
Posted 2011-04-01 10:42:00 and read 7043 times.

Quoting seabosdca (Reply 121):

Hi seabosdca,

Nope, wrong guy - I consider (as mentioned) that B has a (say) 2-year lead in CFRP production technology (they are in serious trouble if they've been through all this and have retained no gain at all!); but then, inevitably, A will catch-up over time.

As far as one putting the other out of business ... Gawd! People like that are a real worry, IMO.
(I am aware that you are in fact being sarcastic about some of the florid stuff that appears on the Forum - and rightly so).


"Market sweeps" can occur (viz the defunct A340) , but are rather rare - for instance, I have elsewhere suggested that a viable B option to the A320neo challenge may prove to be no more than a continuation of the steady product-improvement that has being going-on for so many years; and have enabled it to remain competitive with the (much) later A320 design (the improvements including the CFM56-7B, of course).

The up-gauged A351 as suggested looks like a serious threat to the B77W, however.
And yes, I've followed the range-war on whether or not the rubber-band on the RR can be stretched far enough.
I have no opinion, but can only suggest that if the engine cannot make the thrust, A will not be launching this up-gauged option, but will instead have to stick with what they have been selling so far (GE are not playing, of course).

Which will be a boon for the B77W and B77NG, as well as a great relief for B, IMO.

Billy

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Stitch
Posted 2011-04-01 11:19:56 and read 7033 times.

Quoting frmrCapCadet (Reply 118):
Did Boeing patent the monolithic composite hull, or just one particular way of doing it? The later is what I suspect, and what classically can get a patent. The former is just an idea.

Considering the issues Boeing have had with the production rate - I do not believe the tape-laying machines are still anywhere near what Boeing expected them to be at in terms of fabrication speed - it may be that Airbus went with panels not because they were denied by patents from using similar fabrication techniques, but because they felt such techniques were too inefficient compared to pressed panels, which should have a more...predictable...fabrication rate.

I have always viewed Airbus' talk about being able to replace those panels as a red herring just because of their sheer size. If they expected this work to be done outside of a FAL, they would have used smaller panel sections that could conceivably be removed in a maintenance hangar. I am of the opinion that "ramp rash" will be handled the same as it looks to be handled on the 787 - cut out the damaged area and apply a patch.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Baroque
Posted 2011-04-02 00:10:19 and read 6878 times.

Quoting brindabella (Reply 125):

Nope, wrong guy - I consider (as mentioned) that B has a (say) 2-year lead in CFRP production technology (they are in serious trouble if they've been through all this and have retained no gain at all!); but then, inevitably, A will catch-up over time.

I was just about to respond to include almost exactly this.

Quoting Stitch (Reply 126):
Considering the issues Boeing have had with the production rate - I do not believe the tape-laying machines are still anywhere near what Boeing expected them to be at in terms of fabrication speed - it may be that Airbus went with panels not because they were denied by patents from using similar fabrication techniques, but because they felt such techniques were too inefficient compared to pressed panels, which should have a more...predictable...fabrication rate.

There is someone on a.net who has experience of much bigger and more heavily stressed panels. And IIRC, at the time of the great panel debate, he suggested there were good reasons to prefer panels. In part along the lines that Stitch indicates.

It is clear that the first preference of Airbus was to retain a dominantly metal fuselage - don't forget that the much much larger A380 fuse is already in part composites - but the decision to go with panels was not as forced as some like to suggest. And if B is ahead on CFRP just at present, until the 787 it was even further behind. Just as Airbus being well ahead on composites before the 787 was of marginal advantage, B being ahead (which is still an arguable point) at present would be even more marginal.

Quoting Stitch (Reply 126):
I have always viewed Airbus' talk about being able to replace those panels as a red herring just because of their sheer size. If they expected this work to be done outside of a FAL, they would have used smaller panel sections that could conceivably be removed in a maintenance hangar. I am of the opinion that "ramp rash" will be handled the same as it looks to be handled on the 787 - cut out the damaged area and apply a patch.

   Wonder if they will pre-prepare a few smaller panels for just this eventuality, shaped to fit the more obvious spots for a dose of ramp rash. Like their wings (and like that sheet on the A380 wings), those panels are BIG!

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-04-02 00:33:28 and read 6861 times.

The actual patent is for a "One-piece inner shell for full barrel composite fuselage" - filed in 2006 and published in 2008. Full description here:-

http://www.freepatentsonline.com/7459048.html

If you scroll down you can call up the drawings too.

It seems to have been a genuine 'invention,' requiring all sorts of new techniques and special tools. It therefore looks as if the patent is 'watertight.' Remains to be seen whether Boeing will go on using the full technique on future models.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: packsonflight
Posted 2011-04-02 01:17:38 and read 6814 times.

Quoting Stitch (Reply 126):
I have always viewed Airbus' talk about being able to replace those panels as a red herring just because of their sheer size. If they expected this work to be done outside of a FAL, they would have used smaller panel sections that could conceivably be removed in a maintenance hangar. I am of the opinion that "ramp rash" will be handled the same as it looks to be handled on the 787 - cut out the damaged area and apply a patch.

I agree that it is not practical to change the entire panel, but since the fuse is designed with joints between panels, Airbus is probably planning on making it possible to replace parts of the panel.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: brindabella
Posted 2011-04-03 00:51:53 and read 6548 times.

Quoting Baroque (Reply 127):
Quoting Stitch (Reply 126):
Considering the issues Boeing have had with the production rate - I do not believe the tape-laying machines are still anywhere near what Boeing expected them to be at in terms of fabrication speed - it may be that Airbus went with panels not because they were denied by patents from using similar fabrication techniques, but because they felt such techniques were too inefficient compared to pressed panels, which should have a more...predictable...fabrication rate.

Hi,

thanks. Interesting. - also the Patent application.

Indeed, Albaugh was recently recently reported as saying that only 1/2 the machines would be needed if they could double the lay-up speeds of each machine.

Hard to argue with that - however this seems to me to carry the implication that the machines are quite recent technology(?).


The decision of A to go to "panels" for the A350XWB family was hotly debated here, of course.
The implications of the B Patents were covered; but IIRC, many (or even most) of the viewpoints expressed were directed to the weight implications of the barrel-versus-panel technologies.


Billy

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: TomB
Posted 2011-04-03 03:51:56 and read 6473 times.

I propose that Boeing adopt a "near elliptical" or wide oval fuselage that has twin aisles and have seven abreast seating in a 2 + 3 + 2 configuration. The wide oval fuselage would be 16' 6" wide (the same as a B-767) and 14' 6" high. The wide oval fuselage would have have the same seating configuration as the B-767, yet only 84% of the fuselage frontal area.

The wide oval fuselage would have two LD3-45 containers located side by side in the baggage compartment. Here is a sketch of the wide oval cross section:



In reply 83, bestwestern showed a drawing of the Boeing "near elliptical" fuselage with only one LD3-45W container.

Using the parameters Boeing and NAV20 listed in reply 98, let us compare the wide oval fuselage to the A-320 fuselage. The A-320 fuselage has a perimeter of approximately 500" and the wide oval fuselage has a perimeter of approximately 600". The A-320 carries only one LD3-45W container in the cross section with 130 cubic feet of capacity. The wide oval fuselage carries two each LD3-45 containers with a combined capacity of 220 cubic feet.

The A-320 has a perimeter versus passenger ratio of 83.3. The wide oval fuselage has a perimeter versus passenger ratio of 85.7. The A-320 is 3% better in this comparison.

The A-320 has a perimeter versus cargo capacity of 3.85 and the wide oval fuselage has a perimeter versus cargo capacity of 2.73. The wide oval fuselage is 29% better in the cargo capacity comparison.

By virtue of its twin aisles, the wide oval fuselage will have 60% more overhead baggage capacity than an A-320.

Also due to twin aisles and abundant overhead baggage capacity, the loading and unloading of passengers is facilitated and the twin aisle should have a turnaround time 10 minutes faster than the A-320 or A-321.

With twin aisles and the fact that every passenger is located within one seat of the aisle. passenger comfort is improved.

Based upon the above comparisons, I would say the wide oval fuselage is the clear cut winner.

As Boeing is clearly slotting the B-797 more as a B-757 replacement than a B-737 replacement, the B-797 will fit into a FAA Design Group III gate size with a wingspan of 118' to 170' or a ICAO Design Group D with a wingspan of 36 m to 52 m. Given the wingspan is relatively unconstrained in this Design Group, I think Boeing should design the B-797 around the following specifications:

Base Model:
200 passengers at 32" pitch or 180 passengers in dual class seating.
Trans continental range of 3300 NM.
Cruise speed of M. 84 - M.85.
A high aspect wing of 150' wingspan and approximately 2000 square feet of wing area to give a relatively light wing loading. The wing-sweep will be 32 degrees to permit high speed cruise.
45,000' certified ceiling to permit low fuel burn at high altitudes.
Second generation P&W GTF engine with 15:1 By-Pass-Ratio and improved gas turbine. P&W would probably go to 4:1 reduction gear on the fan to achieve the 15:1 By-Pass-Ratio.

Long-Range Model:
The LR Model would increase engine thrust and increase fuel capacity to permit a maximum range of 4500NM. The aircraft is designed so that a single crew can fly the aircraft for upwards to 10 hours. This aircraft is designed to a be an extremely capable trans-Atlantic aircraft.

Stretched Model:
This aircraft will be a stretch of the Long-Range Model by increasing the single class passenger capacity to 230 to 250 seats and retaining a basic trans-Atlantic range capability of 3800 NM.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: morrisond
Posted 2011-04-03 04:32:23 and read 6408 times.

Nice work.

It looks like your Cargo area is divided in two(would it be a continuous wall? Or just supports every so often?), you could put doors on both sides and speed your cargo unload/load factor by a factor of two.

Maybe bags go on one side, cargo on the other.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-04-03 07:17:07 and read 6304 times.

Quoting flipdewaf (Reply 104):
and the 787 going to be at least another 3 years befor it enters service

Pleased to say that, according to the (usually very reliable) 'Flightblogger's' (Jon Ostrower's) most recent post, it looks more likely to be a matter of less than four months:-

"With the latest iteration of its 787 schedule, Boeing aims to hand over the first aircraft to Japan's All Nippon Airways in late July, the first of 20 planned for delivery in 2011, according to several sources familiar with the new plan.

"While Boeing won't confirm the late July guidance, that target remains in line with an "early summer" completion of flight test activities.

"Industry officials said previously ANA had been provided a September guidance by Boeing for its first delivery following the November 2010 fire that prompted an additional six-month delay in first delivery, though the latest schedule reflects a more optimistic target for first delivery."


http://www.flightglobal.com/articles...s-july-for-787-first-delivery.html

Must admit that, up to this moment, I've tended to 'translate' Boeing's oft-quoted 'third-quarter 2011' guidance as meaning some time in November or December.........

Let's hope Jon is right and all of us aviation nuts can finally look forward to a totally-new aeroplane taking the skies 'in service' in less than four months' time?

[Edited 2011-04-03 07:29:50]

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: TomB
Posted 2011-04-03 07:20:22 and read 6302 times.

Morrisbond, the experts are suggesting I need a portal in the vertical cargo wall at the loading station so that the cargo containers could be loaded on either side of the fuselage. Of course, the wings on the containers have to be positioned correctly before loading.

TomB

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: flipdewaf
Posted 2011-04-03 07:44:20 and read 6274 times.

Quoting NAV20 (Reply 133):

Well it wasnt supposed to be the truth, I weas simply providing a balance to the Boeing fanboy rhetoric that you talk about.

I am very pleased that the 787 will be here soon and with no doubt it will be breaking into the new point to point markets and I will see one at my local airport every day (EGNV).

Fred

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: pylon101
Posted 2011-04-04 00:59:00 and read 6002 times.

Thanks, Tom.
You managed to switch discussion back to the theme of the thread.

I am just wondering what might be a sketch of some narrower 2-2-2 with 2-3-2 option fuselage?
How would you see it?

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: flipdewaf
Posted 2011-04-04 01:31:09 and read 5969 times.

Quoting TomB (Reply 131):
Quoting TomB (Reply 134):
Morrisbond, the experts are suggesting I need a portal in the vertical cargo wall at the loading station so that the cargo containers could be loaded on either side of the fuselage. Of course, the wings on the containers have to be positioned correctly before loading.

TomB


The diving wall isn't added because it is bette to load from both sides, it is added for strength, loading required from both sides is not a good thing. What is the weight addition from adding the centre divide and having a non circular cross section? I think 2-3-2 is much more likely than 2-2-2, 2-2-2 just doesn't provide the airlines with enough for the pain in my opinion.

On the issue of 4-3 seating and claims that it isn't allowed by FAA, I have not seen the actual document that says it isn't allowed (although I trust that people here will not lie). What I do feel however is that the FAA or JAA or any of the others for that matter are not going to blindly disallow something and are willing to change certain aspects through use of demonstrations and "reasonable" measures. I wouldn't automatically write something off, the authorities are not as "non moving" as people perhaps think, I mean new things have to get certificated at some point, they even let us fly planes made of plastic.

Fred

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: pylon101
Posted 2011-04-04 02:49:17 and read 5939 times.

Most a.netters have playing around the existing types IMHO.
But if they proceed with 797 - it is not going to be 767-200 Lite.
At least that's what I see in "Boeing" statements, which are very vague.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: rheinwaldner
Posted 2011-04-04 04:18:46 and read 5900 times.

Quoting TomB (Reply 131):
Based upon the above comparisons, I would say the wide oval fuselage is the clear cut winner.

I think your drawing has some flaws that make it look better than warranted.

Until now it was a given that only a circular cross sections would allow a high structural effiency. Reason was that after pressurizing in all other cases the the walls had to fight against the inside pressure to keep the shape. The resulting cross section is displayed on figure a.) of the attached picture.

Different cross sections


Sometimes non-circular cross sections were used in the past too. I think the DC-9 would be an example or the Nimrod. The principle of their cross section is displayed on figure b.). The floor beams were put under tensile stress to deform the circular appearance. But still the lower and the upper compartement alone were fully circular. Both full circles are displayed on figure b.).

The cross section that is discussed here is c.). It also uses the floor beams to deform the shape by putting them under compression stress. But we still have to assume circular (or close to circular) compartements above and under the floor. And as you can see on the picture, the resulting shape is not nearly as appealing as on your picture:

- The fuselage fluctuates quickly into the passenger compartement.
- The highly relevant fuselage width at shoulder height is compromised at best.
- The available volume for the overhead bins is largely reduced too.
- The cargo compartement can only take one row of containers.

Please notice that a thicker CFRP skin (that is needed for ramp rash) would not help at all because the skin hardly contributes to keeping the cross sectional shape of a fuselage. It would be the job of enforced frames to keep a non circular shape.

Because of that I don't believe that the new 797 will be two aisles...

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: flipdewaf
Posted 2011-04-04 05:03:25 and read 5837 times.

Quoting rheinwaldner (Reply 139):

Well explained!

It should also be pointed out that the relative stiffness increase is much better for a tall oval than for a wide oval. If I remember back to my uni days the A380 was almost spot on with regards to reducing skin thickness because of the tall shape and increasing thickness because of lack of being circular, both were at the same requirement and neither constraint very overengineered.

Fred

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: packsonflight
Posted 2011-04-04 05:18:32 and read 5811 times.

Quoting flipdewaf (Reply 137):
Because of that I don't believe that the new 797 will be two aisles...



I totally agree, but why is Boeing coming up with double aisles solution for the single aisles 737 problem?

Is it because they want to save some bucks, and use the knowledge they have painfully built up for the past years in building CFRP fuse?

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: JoeCanuck
Posted 2011-04-04 06:12:39 and read 5773 times.

Quoting packsonflight (Reply 141):
but why is Boeing coming up with double aisles solution for the single aisles 737 problem?

Boeing is researching a number of ideas. They will go with the one they think will make them the most money in the long run.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-04-04 07:01:49 and read 5727 times.

Quoting TomB (Reply 131):
Using the parameters Boeing and NAV20 listed in reply 98, let us compare the wide oval fuselage to the A-320 fuselage. The A-320 fuselage has a perimeter of approximately 500" and the wide oval fuselage has a perimeter of approximately 600". The A-320 carries only one LD3-45W container in the cross section with 130 cubic feet of capacity. The wide oval fuselage carries two each LD3-45 containers with a combined capacity of 220 cubic feet.

As I understand the engineering, TomB, the 'ideal' cross-section for a pressurised airliner is a circular one. If you 'fancy' making it oval/elliptical (in either direction) you have to make it stronger (and therefore heavier) at 'critical points' - because, as I understand it, said oval, under stress, will try to 'turn itself into' a circular shape.

However, both firms have employed a form of oval fuselage recently - commonly termed the 'double-bubble' (B787, A380, B748). But the 'doubling' in all those cases was in the vertical plane. It begins to look as if Boeing are now thinking in terms of a horizontal double-bubble, allowing more width for less height.

That could have fascinating results if they succeed. Obviously, an aeroplane with a wider fuselage for no greater frontal area, allowing an extra seat per row, could be shorter (and therefore lighter) than any conventional competitor. In addition, as I mentioned earlier, such a fuselage could be designed with a bit of an 'aerofoil section'; it's 'wider than high' shape would generate lift - the old 'lifting body' principle - thus allowing thinner and/or smaller wings, meaning less drag.........

An interesting couple of years ahead, seems to me.

[Edited 2011-04-04 07:22:45]

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: astuteman
Posted 2011-04-04 07:33:46 and read 5697 times.

Quoting NAV20 (Reply 143):
as I mentioned earlier, such a fuselage could be designed with a bit of an 'aerofoil section'; it's 'wider than high' shape would generate lift - the old 'lifting body' principle

I suspect the "lifting body" principle is more likely with the ellipse long axis in the vertical plane.

It is the difference in distance between top and bottom that generates lift, I would have thought.

On that note, the A380's elliptical body in the vertical plane, is known to produce prodigious amounts of "body lift" - a lot more than was originally anticipated.

Rgds

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: zvezda
Posted 2011-04-04 07:42:01 and read 5680 times.

Quoting NAV20 (Reply 143):
It begins to look as if Boeing are now thinking in terms of a horizontal double-bubble

I have not seen any evidence that Boeing are now thinking in terms of a horizontal double-bubble. Any double-bubble design is only efficient if the two intersections are connected (typically by the floor beams). A horizontal double-bubble would need a vertical wall running the length of the aircraft, down the middle, to efficiently retain its shape. I don't think any airline would want that. Rather than a double-bubble, it seems to me that Boeing are looking at the possibility of ovoid cross sections.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-04-04 08:43:41 and read 5610 times.

Quoting zvezda (Reply 145):
I have not seen any evidence that Boeing are now thinking in terms of a horizontal double-bubble.

I suppose that in the end it all boils down to centimetres (inches in my day), zvezda. Boeing, from the patent alone, are very clearly thinking about a 'horizontal ellipse.'

The only question appears to be, can they pull it off? We already know that Airbus isn't even trying to do the same thing?

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: JoeCanuck
Posted 2011-04-04 12:14:43 and read 5499 times.

The wide oval might work with the floor in compression instead of tension. Composites might be just the ticket for this.

That being said, nothing is more efficient than a circle...or two. Any oval needs some bracing against pressurization and that adds weight.

So the question is; what gives the least penalty, the extra weight or the extra drag?

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-04-05 00:43:19 and read 5294 times.

Finally did what I should have done ages ago - looked up the patent itself.

Boeing refer frequently to the words 'near-elliptical.' And, as far as I can decipher the 'elevated' engineering language, the idea is to reinforce the areas which will be subject to increased stress by adding more composite 'plies' at the key points, and also plies at different angles. Effectively, as I understand it, making the fuselage structure thicker where it needs to be thicker to withstand the effects of pressurisation.

http://www.faqs.org/patents/app/20100200697

Looks like yet another genuine 'invention.'

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: pylon101
Posted 2011-04-05 01:50:47 and read 5253 times.

What made you to assume that 797 is going to be composite "full"?
I remember there was direct indication in one of statements/opinions from "Boeing" that it would be mostly Al-Li.
If they plan to build an airplane for 8 cycles a day - they would need much more knowledge of composites.
Th experience of 787 is not available.
Besides, it was discussed that composites are more effective on long routes.
I think it might be composite "lite".

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-04-05 06:35:01 and read 5155 times.

Quoting pylon101 (Reply 149):
What made you to assume that 797 is going to be composite "full"?

Not really referring specifically to the 797 at all, pylon101. Just talking about the method that Boeing have patented. But, all in all, the available information DOES seem to indicate that Boeing are 100% committed to - and comfortable with - monocoque CFRP?

[Edited 2011-04-05 06:44:49]

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: pylon101
Posted 2011-04-05 06:50:15 and read 5123 times.

Sorry, NAV20, I find that I am getting a little bit obsessed with 797 project.
So I apply to 797 what may be applicable or not applicable.

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: Baroque
Posted 2011-04-05 07:00:55 and read 5116 times.

Quoting NAV20 (Reply 148):
http://www.faqs.org/patents/app/20100200697
multi-ply composite structure incorporating at least one of non-metallic and metallic materials
Quite a variety of construction materials seems to be covered.

That would also cover planes made of alternating layers of rock and wood, the angle of the wood being adjusted - just what Airbus has been planning. DRAT!!

Topic: RE: Boeing Twin Aisle Light Jet Economics
Username: NAV20
Posted 2011-04-05 20:29:47 and read 4887 times.

Quoting pylon101 (Reply 151):
Sorry, NAV20, I find that I am getting a little bit obsessed with 797 project.

No problem, pylon101 - must admit, I'm very interested in it too. I suppose Boeing will tell us in July what sort of aeroplane they're going to 'do next,' and it will very possibly be the 797. Agree with you though that conventional wisdom up to now has been that composites offer fewer advantages on smaller aeroplanes. If Boeing really can produce an efficient 200-seater with an elliptical composite fuselage they'll be 'going some'; especially since the fuselage will have to be strengthened at key points, which will presumably mean yet more weight.......


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