Medium capacity fleet options

[cambriamarsh]

There is another thread that discusses QF's potentially largely single aisle future even for 7-9 hours flights such as to Asia. The rationale is it would increase frequency and / or make long thin routes viable. The downside is poor comfort and maybe reduced freight capacity.

Could a short twin aisle circa 200 seater work on those routes?

If not why not?

 

[jb747]

The 767-200 worked extremely well....

 

[justinbrett]

There is another thread that discusses QF's potentially largely single aisle future even for 7-9 hours flights such as to Asia. The rationale is it would increase frequency and / or make long thin routes viable. The downside is poor comfort and maybe reduced freight capacity.

There's plenty of posters in that thread who labelled that article as clickbait. There's no basis for the claims.

Qantas has said it's replacing its A330s

Qantas to replace A330s with Airbus A350s, Boeing 787s

Get ready to see domestic Dreamliners on Australia’s east-west route.

www.executivetraveller.com

 

[cambriamarsh]

There's plenty of posters in that thread who labelled that article as clickbait. There's no basis for the claims.

Qantas has said it's replacing its A330s

Qantas to replace A330s with Airbus A350s, Boeing 787s

Get ready to see domestic Dreamliners on Australia’s east-west route.

www.executivetraveller.com

Understand that, but it does bring up a good point. Most passengers prefer a twin aisle but the current crop seem a bit on the large side for a thin route. Is there any reason not to build say a 140 to 170 seat twin aisle plane? The proportions might look a little unusual but could it work technically and commercially?

 

[justinbrett]

Understand that, but it does bring up a good point. Most passengers prefer a twin aisle but the current crop seem a bit on the large side for a thin route. Is there any reason not to build say a 140 to 170 seat twin aisle plane? The proportions might look a little unusual but could it work technically and commercially?

That's fewer seats than a 737-800.

A310 is the smallest widebody built as far as I'm aware, that had 190-230 seats - with most operators at or close to the 230 end.

Qantas configures it's 787-9 with 236 seats and its least dense A330-200 with 234, so both seem like a good incremental step up from B737/A320 that's not huge.

They generally don't build aircraft for passenger comfort - twin aisle jets are a function of the size of the fuselage and the number of seats.

The 797, if it's ever built, will be the perfect aircraft for this market - it's tipped to have a 2-3-2 configuration, just like the 767.

 

[oz_mark]

Understand that, but it does bring up a good point. Most passengers prefer a twin aisle but the current crop seem a bit on the large side for a thin route. Is there any reason not to build say a 140 to 170 seat twin aisle plane? The proportions might look a little unusual but could it work technically and commercially?

Technically it could work, however, I think single aisles will always have a commercial advantage for an aircraft that size.

 

[Forg]

Do most passengers prefer a twin aisle because a lot of twin aisle aircraft are set-up for longer flights and single-aisle aircraft are mostly set-up for shorter flights? Airlines don’t have to run a smaller pitch in a 737 than a 787. And TBH by the time I get to the end of 13 hours in the Metal Tube Of Death I’m REALLY happy to escape … if you’re the majority, hence in Y, it’s way quicker getting out of a 737 than a 787.

 

[elanshin]

Understand that, but it does bring up a good point. Most passengers prefer a twin aisle but the current crop seem a bit on the large side for a thin route. Is there any reason not to build say a 140 to 170 seat twin aisle plane? The proportions might look a little unusual but could it work technically and commercially?

It'd be up against a lot of stiff competition in the single aisle segment. The R&D cost for such an aircraft would never make it past the business case in the current environment.

The A220 despite it being single aisle has been touted as a game changer in this market size for passenger comforts so perhaps we'll see if that can change people's opinions. I believe it has just enough range for the northern cities to reach South East Asia if they choose to take it international.

 

[Forg]

It'd be up against a lot of stiff competition in the single aisle segment. The R&D cost for such an aircraft would never make it past the business case in the current environment.

The A220 despite it being single aisle has been touted as a game changer in this market size for passenger comforts so perhaps we'll see if that can change people's opinions. I believe it has just enough range for the northern cities to reach SEA if they choose to take it international.

Yes QF published a map, I can’t get the image reference properly on this iPad so I’ll paste the link below.
Short version though is from Sydney or Melbourne or Brisbane they can get to Bali & Indonesia, from Perth they can get further to Singapore or Cambodia or Thailand or Malaysia or Philippines.

qantas a220 range - Google Search

 

[cambriamarsh]

Technically it could work, however, I think single aisles will always have a commercial advantage for an aircraft that size.

Thanks Oz, why is there a commercial advantage to single aisle at this size?

 

[Forg]

Thanks Oz, why is there a commercial advantage to single aisle at this size?

It would need a change in design compared to what the current crop of commercial aircraft look like, wouldn’t it? A stumpy 787, let’s call it a 787-3 … … would have some fuel consumption issues per-passenger due to wind resistance vs the large cross-sectional area? You’d be looking at something half the size of a 787-8 … 150 pax at 9/row is only going to be about 20 rows of seats allowing for an upfront J, so it’s shorter than a 737-400 (they had about 22 rows?).

Maybe one of those flying-wing designs could be perfected, but that introduces problems with ground infrastructure.

I think one part of it, without redesigning, is that a 2nd aisle means dragging extra real-estate up into the sky unless you can fit twice as many seats across a row as a single-aisle … so to compete with an A321XLR (1 aisle-width every 6 Y seats) with a twin-aisle design you’d need to get 12 Y seats into a row. That’s of course a comparison utilising the current design approach; anything’s possible with a new design.

 

[Quickstatus]

wind resistance vs the large cross-sectional area

Drag comes in several forms

Form drag which is determined by the cross sectional area of the object travelling through a fluid (air) creating pressure differences
There is induced drag caused by an airfoil creating lift
There is surface drag which is caused by the friction of the travelling surface

Then consider 2 single aisle vs 1 twin aisle each of equivalent range and seats. 2 single aisles will require 4 engines, 4 wings, 4 tails, The single twin aisle only 2 engines, two engines, one tail.

Do 2 single aisles have less drag than 1 twin aisle?

 

[Forg]

Drag comes in several forms

Form drag which is determined by the cross sectional area of the object travelling through a fluid (air) creating pressure differences
There is induced drag caused by an airfoil creating lift
There is surface drag which is caused by the friction of the travelling surface

Then consider 2 single aisle vs 1 twin aisle each of equivalent range and seats. 2 single aisles will require 4 engines, The single twin aisle only 2 engines. Do 2 single aisles have less drag than 1 twin aisle?

Per passenger? Possibly. The two single-aisle aircraft are carrying twice as many passengers in this scenario. Unless the twin-aisle aircraft is the size they currently are, which is outside the scope of this discussion ("why not have an A321-capacity twin-aisle aircraft").

 

[Quickstatus]

Possibly

However to compare on a per passenger basis note that I said "equivalent range and seats". Need to compare apples with apples.
In the end issues of drag are more in the realm of fluid dynamic engineers which very few understand without supercomputers. AFF speculation on an laptop does not get very far fortunately

 

[Forg]

However to compare on a per passenger basis note that I said "equivalent range and seats". Need to compare apples with apples.

That's my point.

1. If you're carrying the same number of people in the two single-aisle aircraft as you are in one double-aisle aircraft, then you have the current scenario - twin-aisle aircraft are twice as large.
2. But if the aircraft have the same carrying-capacity as each other, then two single-aisle aircraft are carrying twice as many passengers as your one twin-aisle aircraft is ...

So on a per-passenger basis, the single-aisle still has less cross-sectional area per passenger. Admittedly, to your 2nd point, whatever that actually means ...

There's still the issue of carrying the weight (ie. including structure to support that aisle) of a seat-sized piece of aisle every 6 pax in a 737 vs every 4.5 or 5 pax (because 2 aisles for a 9 or -ick- 10-seat row) in a 787. That's gotta be a cost, in fuel as well as cost-to-build.

 

[justinbrett]

The A220 despite it being single aisle has been touted as a game changer in this market size for passenger comforts so perhaps we'll see if that can change people's opinions. I believe it has just enough range for the northern cities to reach SEA if they choose to take it international.

Northern cities of where? I assume not Australia - A220 wouldn't even get to HNL, let alone SEA.

 

[Quickstatus]

the single-aisle still has less cross-sectional area per passenger

That is not all the sources of drag. You forgot the other significant causes of drag.
Currently there are no single aisles with the capacity of twin aisle. So best comparison would be to control for number of aisle, range and seats.

2nd point, whatever that actually means

It means AFF speculation on a laptop vs fluid dynamic engineer and supercomputers. I know who is likely to be right.
Also I neglected to include windtunnel data.....

Work this out (AFF simplified version):
D = C𝙙 (rV²/2)A
C𝙙 = C𝙙0 +Ci²/(𝜋Aᵣe)

D= Drag
C𝙙 = drag coefficient,
C𝙙0 = Cd at zero lift (equivalent to skin friction and form drag)
Ci = induced drag
𝜋 = 3.1415...
A = wing area
e = Oswald efficiency factor
r = air density
Aᵣ = wing aspect ratio which is very simply S²/A
S = wing span

 

[lovestotravel]

Get all A330 crew onto cheap purchased 787s and those staff contracts or get them onto A330neos and pay them less again

A beancounters dream, and once the 737s and A380s are gone ...

 

[elanshin]

Northern cities of where? I assume not Australia - A220 wouldn't even get to HNL, let alone SEA.

Sorry mis communication should have written South East Asia instead of SEA.

 

[Quickstatus]

Why did Boeing stop production of the 757?