atomicstar
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Why can’t aircraft maximize fuselage space by using ceiling space?

Sat Jun 08, 2019 10:18 pm

I got this idea after reading an investigation report on the 2001 Japan Airlines near mid air collision incident. Of one of the pictures was the ceiling space in which a galley cart got jumped into the ceiling space due to evasive maneuvers.

Image

Now thinking of this, why can’t large aircraft like B747 maximize fuselage space by using the ceiling space for maybe second cargo hold, or lavatories? I understand that some of it is used for equipment and structure, but adding walls and floor and a door could allow it to be used for cargo. Or also add stairs to put lavatories there, allowing more lavatory stalls there (kinda like the L-1011’s rear semicircle of 5 lavatory stalls) and therefore passengers don’t need to wait in line so long to go to the toilet. I get that they probably can’t make it an upper deck seating because there isn’t enough headroom and there’s stuff like structure and equipment as walking obstacles
 
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AirKevin
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Sat Jun 08, 2019 10:27 pm

How would you get the cargo up there.
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SteelChair
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Sat Jun 08, 2019 11:31 pm

There would be structural issues for cargo.

I've wondered since the inception ofthe 777 overhead crew rest modules why airlines didn't sell passenger space up there. Real bunks and more space trump lie flat seats.
 
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AirKevin
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Sat Jun 08, 2019 11:45 pm

SteelChair wrote:
I've wondered since the inception ofthe 777 overhead crew rest modules why airlines didn't sell passenger space up there. Real bunks and more space trump lie flat seats.

I guess that depends on your definition of more space, but judging by the pictures I've seen, you wouldn't really be able to stand up straight at all. Imagine having to crawl or crouch from one end of the plane to the other.
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kalvado
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Sun Jun 09, 2019 12:02 am

AirKevin wrote:
SteelChair wrote:
I've wondered since the inception ofthe 777 overhead crew rest modules why airlines didn't sell passenger space up there. Real bunks and more space trump lie flat seats.

I guess that depends on your definition of more space, but judging by the pictures I've seen, you wouldn't really be able to stand up straight at all. Imagine having to crawl or crouch from one end of the plane to the other.

Even better, imagine doing that for 90 second evacuation.
 
SteelChair
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Sun Jun 09, 2019 12:40 am

Good point on the evacuation.

Yeah, its not real tall, but the Flt Attendant unit is like 30 feel long for only 8 bunks. Lots of room, much more than on many private jets.
 
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DocLightning
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Sun Jun 09, 2019 1:14 am

SteelChair wrote:
There would be structural issues for cargo.

I've wondered since the inception ofthe 777 overhead crew rest modules why airlines didn't sell passenger space up there. Real bunks and more space trump lie-flat seats.


This was proposed by Boeing, but airlines were not interested.

1) You cannot seat additional passengers up there because there is no emergency egress. Once the A/C is above FL100 then passengers could be allowed to occupy that space since an emergency evacuation from FL100 or above is not going to happen (if an emergency happens up there that is survivable, the passengers would have time to come back down to the main cabin and take their seats before landing).

2) They considered adding berths for sleeping up there that would be available at an additional cost, but the fare per berth charged to the pax that would justify the cost of certifying and installing the berths basically made it such that it would make as much sense for a Y pax to just purchase a J seat with a lie-flat feature.
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VSMUT
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Sun Jun 09, 2019 5:14 pm

Putting seating up there has been discussed (and proved inefficient due to emergency evacuation) loads of times, but how about other functions that could release main-deck space for seating? The A340-600 placed some galleys and lavatories under the cabin. By placing them above the cabin, you don't infringe on cargo space either. Would be possible on the 777X, no?
 
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AirKevin
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Sun Jun 09, 2019 6:18 pm

VSMUT wrote:
Putting seating up there has been discussed (and proved inefficient due to emergency evacuation) loads of times, but how about other functions that could release main-deck space for seating? The A340-600 placed some galleys and lavatories under the cabin. By placing them above the cabin, you don't infringe on cargo space either. Would be possible on the 777X, no?

How much standing room would be available for the flight attendants to be able to work comfortably if you put the galleys above the cabin. Putting it below is one thing, you've got plenty of standing room there.
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WPvsMW
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Sun Jun 09, 2019 6:23 pm

"Crouching galleys" and "crouching lavs" above the main cabin... that should work, Airbus strayed too far in the A380. 1.5 decks would have saved the program. ;) :shock: :lol:
 
VSMUT
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Sun Jun 09, 2019 6:53 pm

AirKevin wrote:
VSMUT wrote:
Putting seating up there has been discussed (and proved inefficient due to emergency evacuation) loads of times, but how about other functions that could release main-deck space for seating? The A340-600 placed some galleys and lavatories under the cabin. By placing them above the cabin, you don't infringe on cargo space either. Would be possible on the 777X, no?

How much standing room would be available for the flight attendants to be able to work comfortably if you put the galleys above the cabin. Putting it below is one thing, you've got plenty of standing room there.


Just turn it 90 degrees and place it longitudinally. There is enough space to stand up in the middle.

Even if that isn't an option, what would prevent them from putting a pair of lavatories there?
 
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AirKevin
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Sun Jun 09, 2019 7:54 pm

VSMUT wrote:
AirKevin wrote:
VSMUT wrote:
Putting seating up there has been discussed (and proved inefficient due to emergency evacuation) loads of times, but how about other functions that could release main-deck space for seating? The A340-600 placed some galleys and lavatories under the cabin. By placing them above the cabin, you don't infringe on cargo space either. Would be possible on the 777X, no?

How much standing room would be available for the flight attendants to be able to work comfortably if you put the galleys above the cabin. Putting it below is one thing, you've got plenty of standing room there.


Just turn it 90 degrees and place it longitudinally. There is enough space to stand up in the middle.

Even if that isn't an option, what would prevent them from putting a pair of lavatories there?

Passenger comfort?
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Armadillo1
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Mon Jun 10, 2019 12:33 pm

not full lavatories but part of them. catering storages. lowered part of kitchens. even with travolators lol
 
kalvado
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Mon Jun 10, 2019 1:11 pm

AirKevin wrote:
VSMUT wrote:
AirKevin wrote:
How much standing room would be available for the flight attendants to be able to work comfortably if you put the galleys above the cabin. Putting it below is one thing, you've got plenty of standing room there.


Just turn it 90 degrees and place it longitudinally. There is enough space to stand up in the middle.

Even if that isn't an option, what would prevent them from putting a pair of lavatories there?

Passenger comfort?

what??
 
VSMUT
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Mon Jun 10, 2019 3:46 pm

AirKevin wrote:
VSMUT wrote:
AirKevin wrote:
How much standing room would be available for the flight attendants to be able to work comfortably if you put the galleys above the cabin. Putting it below is one thing, you've got plenty of standing room there.


Just turn it 90 degrees and place it longitudinally. There is enough space to stand up in the middle.

Even if that isn't an option, what would prevent them from putting a pair of lavatories there?

Passenger comfort?



What do you mean, passenger comfort? Main deck space is a premium, the tiny AA 737MAX toilets are an example hereof. Plenty of space for large lavatories up above.
 
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AirKevin
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Mon Jun 10, 2019 4:19 pm

VSMUT wrote:
AirKevin wrote:
VSMUT wrote:
Just turn it 90 degrees and place it longitudinally. There is enough space to stand up in the middle.

Even if that isn't an option, what would prevent them from putting a pair of lavatories there?

Passenger comfort?

What do you mean, passenger comfort? Main deck space is a premium, the tiny AA 737MAX toilets are an example hereof. Plenty of space for large lavatories up above.

Never been on board an American Airlines 737MAX before, so I don't know how small the lavatories are there. In any event, I don't think you have to worry about crouching when you're in the lavatory on the main deck. Not necessarily the case if you put it on the ceiling.
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PatrickZ80
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Mon Jun 10, 2019 5:31 pm

AirKevin wrote:
How would you get the cargo up there.


It wouldn't, but here's another idea. Very simplistic, but here are two different cabin layouts:

Image

Image

Both of them have the exact same distance between the floor and the ceiling, so their cabins are equally high. Only in the first there is a lot of unused space above the ceiling while there is less space beneath the floor for cargo. In the second, the cabin floor and ceiling are placed higher. This means the amount of empty space above the ceiling is reduced to almost zero while at the same time there is more space beneath the floor for cargo.

I always found it kind of ridiculous that wide body aircraft had to have their passenger cabin in the middle. By placing it higher, you can make better use of the space you got.

Of course it's impossible to convert existing aircraft to this new cabin design as the doors and windows would be out of place. But it could be used in future aircraft types.
 
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AirKevin
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Mon Jun 10, 2019 8:33 pm

I actually don't see how that idea would be any better. If you take into consideration the curvature of the fuselage, whoever has the window seat is not going to have a whole lot of space without hitting the wall.
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Dalmd88
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Tue Jun 11, 2019 12:03 am

In reality the floor to ceiling ratio is a lot closer to the lower drawing. The floor is located near the center of the tube to maximize floor space for more seats. There really isn't that much room above the drop ceiling of most widebody jets. Yes there are crew rest rooms in the 777. It's like being in a kids tree house.
 
JayinKitsap
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Tue Jun 11, 2019 1:41 am

Fuel tanks could go up there.

What could possibly go wrong ?! ?! !! :cry2:
 
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Starlionblue
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Tue Jun 11, 2019 3:18 am

Aircraft are typically weight limited anyway. Extra room to stow stuff doesn't do any good if you're maxed out on weight.

Dalmd88 wrote:
In reality the floor to ceiling ratio is a lot closer to the lower drawing. The floor is located near the center of the tube to maximize floor space for more seats. There really isn't that much room above the drop ceiling of most widebody jets. Yes there are crew rest rooms in the 777. It's like being in a kids tree house.


Just so.

In the A350 crew rest bunks I easily reach the ceiling with my hand while lying on my back. By contrast, the cargo spaces take full-size aircraft cargo containers. There's a massive difference in height.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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Starlionblue
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Tue Jun 11, 2019 4:43 am

You can see in these cross-sections how the cargo space is much "taller" than the crown

777
Image

A350
Image
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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TWA772LR
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Tue Jun 11, 2019 4:46 am

Forget bunks, labs, and cargo. Put lounges up there! Couches and seats on the sides and the pathway in the middle so you can stand/walk. It could be an EK style bar, 70s style lounge, or flying mobile airline lounge.
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Tue Jun 11, 2019 8:29 am

TWA772LR wrote:
Forget bunks, labs, and cargo. Put lounges up there! Couches and seats on the sides and the pathway in the middle so you can stand/walk. It could be an EK style bar, 70s style lounge, or flying mobile airline lounge.

Nowhere near room enough to stand up, even in the middle. You might could put down a few tatami mats, toss in a few throw pillows, dim the lights, and go for the "opium den" look because everyone would have to crawl around on their hands and knees anyway.
Able to kill active threads stone dead with a single post!
 
trijetsonly
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Tue Jun 11, 2019 1:26 pm

You could buy your 747 with a berth section in the crown.
https://www.greenpoint.com/747-8-aeroloft/

Though this is a cool offer, the operational penality for airlines is probably not worth it.
Happy Landings
 
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trpmb6
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Tue Jun 11, 2019 2:45 pm

Keep in mind weight and CG considerations. As well as the fact that your ceiling structure must now also be sized to carry the additional loads of anything up there.

It's also not as much space as you really think it is. Especially once you start fitting in all the interior stuff required.
 
CRJ900
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Thu Jun 13, 2019 5:57 pm

Nerd trivia maybe, but Sterling Airways had duty free cigarettes in the ceiling on their B727-200Adv - the aircraft had two above-aisle compartments for rafts, but they stored big bags with duty free cigarettes there instead. All cigarettes were sold by the time the aircraft came back to base, and many passengers jumped in their seat when the FAs suddenly lowered the compartments (they made a particular sound) and took out the bags and brought them to the galley.

Lauda Air had six ATLAS boxes stowed in the ceiling in the mid-cabin galley on their B777-200ER, 3x3. One FA showed me on a long flight VIE-KUL.
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Fri Jun 14, 2019 1:07 am

CRJ900 wrote:
Nerd trivia maybe, but Sterling Airways had duty free cigarettes in the ceiling on their B727-200Adv - the aircraft had two above-aisle compartments for rafts, but they stored big bags with duty free cigarettes there instead. All cigarettes were sold by the time the aircraft came back to base, and many passengers jumped in their seat when the FAs suddenly lowered the compartments (they made a particular sound) and took out the bags and brought them to the galley.

Lauda Air had six ATLAS boxes stowed in the ceiling in the mid-cabin galley on their B777-200ER, 3x3. One FA showed me on a long flight VIE-KUL.



Ok i’ll bite, what
is an ATLAS box ?
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DL_Mech
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Fri Jun 14, 2019 2:24 am

This plane is built to withstand anything... except a bad pilot.
 
tommy1808
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Mon Jun 17, 2019 1:12 pm

PatrickZ80 wrote:
AirKevin wrote:
How would you get the cargo up there.


It wouldn't, but here's another idea. Very simplistic, but here are two different cabin layouts:


Trade offs...

Few fuselages are circular, most are Doubles Bubble. For those the cabin floor has to be where both radii touch or the fuse gets heavy to bear the load of all the pressure inside.

Best regards
Thomas
This Singature is a safe space......
 
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longhauler
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Mon Jun 17, 2019 6:58 pm

Starlionblue wrote:
Aircraft are typically weight limited anyway. Extra room to stow stuff doesn't do any good if you're maxed out on weight.

I would guess this is the main reason. It's pretty rare on a longer international flight that one is not approaching Performance MTOW. So if weight restricted and not volume restricted, increasing volume won't help you if you can't lift it.

By comparison, many many years ago when I was flying Cargo and Combi 737 freighters into Canada's arctic, volume almost always was the biggest issue as we carried a lot of dry goods north that were not very "dense".

CRJ900 wrote:
Nerd trivia maybe, but Sterling Airways had duty free cigarettes in the ceiling on their B727-200Adv - the aircraft had two above-aisle compartments for rafts, but they stored big bags with duty free cigarettes there instead. All cigarettes were sold by the time the aircraft came back to base, and many passengers jumped in their seat when the FAs suddenly lowered the compartments (they made a particular sound) and took out the bags and brought them to the galley.


I love "nerd trivia" like this!
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Fars
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Tue Jun 18, 2019 1:59 am

tommy1808 wrote:
PatrickZ80 wrote:
AirKevin wrote:
How would you get the cargo up there.


It wouldn't, but here's another idea. Very simplistic, but here are two different cabin layouts:


Trade offs...

Few fuselages are circular, most are Doubles Bubble. For those the cabin floor has to be where both radii touch or the fuse gets heavy to bear the load of all the pressure inside.

Best regards
Thomas

Reduce the pressure on the fuselage in the air,the design of any aircraft is the result of the tradeoffs and pressures of being in the air.
 
spantax
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Tue Jun 18, 2019 12:40 pm

Dear Airbus, Boeing, Gentlemen,

Here is the answer: make a square fuselage, à la Shorts 360. No lost spaces, although a little sensitivity to cross winds, I presume.

https://www.airliners.net/photo/Untitle ... wv9w%3D%3D

Regards.
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atomicstar
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Wed Jun 19, 2019 1:45 am

spantax wrote:
Dear Airbus, Boeing, Gentlemen,

Here is the answer: make a square fuselage, à la Shorts 360. No lost spaces, although a little sensitivity to cross winds, I presume.

https://www.airliners.net/photo/Untitle ... wv9w%3D%3D

Regards.


But also is going to be an issue with designing the structure as it needs to be pressurized. It is a lot harder to support a rectangular shape pressurized than a circular shape.

The Shorts 360 is not pressurized
 
SAAFNAV
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Wed Jun 19, 2019 5:09 am

spantax wrote:
Dear Airbus, Boeing, Gentlemen,

Here is the answer: make a square fuselage, à la Shorts 360. No lost spaces, although a little sensitivity to cross winds, I presume.

https://www.airliners.net/photo/Untitle ... wv9w%3D%3D

Regards.


I'm sure the top designers are looking at each other flabbergasted and saying 'well, why didn't we ever think of that!?'
L-382 Loadmaster; ex C-130B Navigator
 
PC12Fan
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Re: Why can’t aircraft maximize fuselage space by using ceiling space?

Thu Jun 27, 2019 1:13 am

Galley storage has been pushed for years IIRC. As far as lounges goes, not many humans would be interested in standing in a lounge environment anyways.
Just when I think you've said the stupidest thing ever, you keep talkin'!

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