Designing a very, very large airliner… [Archive]

medviation

6th Feb 2016, 20:35

…yes it may not have much business sense right now but I had this nagging curiosity on how big airplanes can get since the flight of the A380. Yes you can say there’s no limit from a technical standpoint. As long as you have enough materials and power, a plane with a 10 kilometer wingspan carrying a million people can be built, right? But I’m not here to argue that.

It has been stated that the A380 (particularly the planned but undeveloped A380-900) maxes out the 80x80m box agreed upon by airports around the world. How can an airliner become even bigger without rewriting all the rules of airport infrastructure, without inventing extremely advanced technologies and without sacrificing comfort and performance big jetliners have today? The question is: what is the biggest airliner we can build and certify now?

I’ve taken a look at several concepts intended for large transport aircraft from flying wings to “sky-whales” until I found a design with huge potential for VLAs. It’s called the box wing.

Here’s a video (https://www.youtube.com/watch?v=wTl9EyKonkk) of a box wing being tested in flight.

More about box wings here (http://www.airport2030.de/Dokumente/Publikationen/TextKhan.pdf). Also see page 45 further explaining the potential of box wings for very large aircraft.

So here is my design solution:

http://s2.postimg.org/e3sxkqeh5/presentation_002.png

http://s29.postimg.org/r99dt3wdz/presentation_003.png

WINGS

More reasons why I chose a box wing:

1. In a forward-backward swept wing combo with enough vertical separation a box wing will have a huge lifting capability needed for a wingspan-constrained aircraft.
2. It naturally has very good vortex reducing wingtip devices.
3. It has a relatively strong structure compared to a single cantilever wing. This can allow for a thinner, lighter wing structure.
4. Box wings can eliminate the need for a separate horizontal stabilizer.
5. The brackets that close the wingtips can double as a vertical stabilizer and rudder.
6. The wing configuration can allow significantly more yaw, pitch and roll control options.
7. Engines can be mounted on the top wing giving them significant ground clearance to prevent ingestion of FOD. This also allows for space for ever expanding bypass ratios of aircraft engines.

FUSELAGE

Making the most out of the lift the wings are capable of, I found a triple-decker, multi-bubble to be the best design: 3-4-3 upper deck, 3-6-3 main deck and 3-6-3 lower deck giving the cross-section total of 34-abreast compared to total 18-abreast (potential 19-abreast) A380. This easily fits 1,000 in 3-class configuration. The design also eliminates the need for three or more aisles which poses hazards to emergency evacuation process.

FRONT CENTER WING BOX

To make this plane competitive in belly cargo capacity, I have placed the front center wing box through the lower deck cabin. This design makes for a continuous belly cargo hold that can accommodate 94 LD3 containers. There will be two corridors cutting through the wing box that will act as passage between the front and rear cabin. Instead of fuel tanks, the leftover space can be used for galley storage leaving the rest of the cabin for passengers.

PASSENGER/CARGO LIFT

Aside from the two staircases, the three passenger decks will be connected via lift. This is for the purpose of transporting persons with disability between decks as well as beverage trolleys, among many others. The lift will be located aft of the wing box.

ATRIUM & MEZZANINE

Since the curvature of the fuselage nose cone will cause the upper deck’s ceiling to curve downward, the space at the front will be of little use, so I decided to cut the upper deck’s floor short in order to create a mezzanine that overlooks a small atrium on the main deck. This is also where the main staircase is located giving an impression of a grand hall for passengers entering the aircraft. Due to this, the main deck atrium can only have limited overhead bins so this space can be used as a lounge or shop by premium carriers but it can also be used for more seats by LCCs.

I am not a certified engineer whatsoever and I have never formally studied engineering or aeronautics in my life. Compared to professionals, I only have a rudimentary understanding of aircraft design. I have a background though in architecture hence, some proficiency in 3D modeling.

Thank you for taking the time to read my post. I’ll post more detailed renderings soon. Anyway could it work? What do you think?

I have searched far and wide to find a place to share this where there are people with much expertise on the subject. I hope this is the right place to post this. If not, feel free to move this thread. Also I am inspired by keesje (http://www.pprune.org/members/196250-keesje) with his work with the Turboliner, Greenliner and the Ecoliner among many others.

goeasy

7th Feb 2016, 03:30

I don't think many airports pavement would carry that load. A lot of airports needed strengthening etc for the A380.

Junkflyer

7th Feb 2016, 05:45

It is a huge undertaking to make an airport usable for the A380. Very expensive and time consuming.The required space for runways, taxiways,clearways and gates is burdensome as is. To go even larger is probably uneconomical. Gate space is at a premium at many airports, larger gates mean less total available.

Tourist

7th Feb 2016, 06:21

Your rudders "J"

They are at the midpoint-ish.

This means that they will not produce yaw. At best they would move the aircraft sideways, though if differential you could get some yaw as a secondary effect I suppose.

Tourist

7th Feb 2016, 07:13

I can only imagine that ground effect must be a pig on landing w.r.t. pitch control in box configuration aircraft.

Tourist

7th Feb 2016, 07:18

Why design an aircraft with 6 engines?
Plenty of room for 4 777 engines.

Less is better for efficiency, reliability (6 times more likely to have an engine failure than a one engined aircraft)

Stanwell

7th Feb 2016, 07:44

medviation,
Thanks for an interesting and well presented post.

On the subject of lifting surfaces, particularly of the box design, a distant relative of mine published a number of papers on the subject.
His research produced a number of interesting findings which significantly advanced aviation technology.

You might have heard of him - Lawrence Hargrave. :cool:

p.s. He later regularly corresponded with and advised a couple of Americans called Wilbur and Orville.
Thankfully, he lived to see his dream realised - powered and controlled manned flight.
.

eckhard

7th Feb 2016, 08:30

I think it looks great. A clever way of fitting inside the 80m box while doubling capacity.

As the rudders at 'J' are split, I think they would work just fine for yaw control, using asymmetric drag.

One concern could be the position if the engines behind the front wing. At moderate angles of attack they may encounter disturbed air.

Why don't you send your ideas to the Royal Aeronautical Society? I'm sure they would be interested and have some well-qualified people to give constructive feedback, instead of the nit-picking you may encounter here.

GordonR_Cape

7th Feb 2016, 08:41

A fascinating excercise from a drawing point of view! However I can imagine a number of downsides in terms of structural strength, center-of-gravity, air-flow, economics, efficiency, stability, undercarriage, etc.

Tourist

7th Feb 2016, 09:36

As the rudders at 'J' are split, I think they would work just fine for yaw control, using asymmetric drag.

How many aircraft can you think of that use asymmetric drag for yaw control eckhard?

it is just not an efficient way of providing yaw control if you already have vertical surfaces

cattletruck

7th Feb 2016, 09:44

Happened in Singapore last year. A number of arrivals left the terminal staff running very thin. There were only enough staff to allow us to board our A380 via one door. Delayed us an extra 30 minutes.

cavok_flyer

7th Feb 2016, 10:31

I'm thinkin' deep stall here... Other than that , it looks great. :ok:

eckhard

7th Feb 2016, 10:47

How many aircraft can you think of that use asymmetric drag for yaw control eckhard?

Only one; the B-2. Are there others?

Tourist

7th Feb 2016, 11:17

Only one; the B-2. Are there others?

Not that I can think of, and the B2 does not have them because they are a good idea aerodynamically......

Capot

7th Feb 2016, 11:47

I can only add to the responses about airports.

It is much, much easier to design and build a very large aircraft such as this one than it is to create the environment in which it can operate at its full potential.

The airport industry has not really caught up with the B747, or any other later aircraft offering similar passenger loads. And the B747 first flew in the 1960's.

Most airports simply create parking stands for the large aircraft, and consider their job done. They might have to upgrade pavement strengths as well.

But the real problems with these aircraft start in the terminal, airdide and landside, where few if any airports are really designed to cope efficiently with the peak flows these aircraft generate. Just as a starter, think how long it takes to deplane a full B747, and then wonder why such nonsense happens. It's not set in the Holy Writ that you can only use 2 doors; but most airport managements and their architects believe that it is, which is why it is now a "fact of life" that no-one dares to challenge. Well, I do. (In BAA that meant a lot of unpleasant meetings, usually with a bunch of grocers talking about "footfall" and how to prolong passengers' misery so that they had more time to buy over-priced tat.)

Intermineable queueing in both directions, crowded discomfort, inability to handle massive disruption for reasons such as fog, are all the consequences of airport owners and managements failing totally to grasp their responsibilities as opposed to maximising their retail spend. The excuse that problems are exacerbated by security does not wash any longer. The industry has had 15 years to catch up with that, or rather the USA has had 15 years, the rest of the world 50 years.

My heart sinks when I see brand new, beautiful, modern terminals (eg LHR T5 and T2) which simply perpetuate the fundamental design flaws of their predecessors, wrapped up to look, but not to be different.

So, my suggestion is to put away the aircraft design, and focus on airport design. Bin all the received wisdoms that architects and layout designers hold so sacred. Start afresh. Use technology imaginatively, rather than as a means of just automating and consolidating existing processes and methods. Unless someone does that, the world's airports will always be the reason we cannot advance.

Ex Cargo Clown

7th Feb 2016, 12:24

It looks lovely, BUT

As said above, there would be so many ground handling issues. Checkin, Immigration, baggage, you name it, plus You'd have all manner of PCN issues at that weight.

Maybe it might make a specialised freighter at some adapted airports?

Good luck though

medviation

7th Feb 2016, 12:42

Wow thanks so much for the many replies! :)

I don't think many airports pavement would carry that load. A lot of airports needed strengthening etc for the A380.

Good point. But I wasn't too familiar with airport pavement design. I thought if I added more wheels the distribution of weight will be spread out similar to an A380 or 747. Could you share some numbers?

It is a huge undertaking to make an airport usable for the A380. Very expensive and time consuming.The required space for runways, taxiways,clearways and gates is burdensome as is. To go even larger is probably uneconomical. Gate space is at a premium at many airports, larger gates mean less total available.

I think you're missing the point. I'm trying to look at a design that would allow more payload than an A380 without going beyond the runway, taxiway, gate requirements of an A380.

I can only imagine that ground effect must be a pig on landing w.r.t. pitch control in box configuration aircraft.
One concern could be the position if the engines behind the front wing. At moderate angles of attack they may encounter disturbed air.
I'm thinkin' deep stall here...

I guess so, but well never know without simulation and testing.

Why design an aircraft with 6 engines?
Plenty of room for 4 777 engines.

Less is better for efficiency, reliability (6 times more likely to have an engine failure than a one engined aircraft)

I know, except 4 777 engines is not enough. An airplane this size may require 645kN thrust each compared to 514kN of the GE90. This would require a totally new engine technology.

ManUtd1999

7th Feb 2016, 13:30

Manufacturing the complex wing-joint sections would be difficult/expensive...

LlamaFarmer

7th Feb 2016, 14:51

Curiosity not criticism - why did you go for that design rather than a Blended wing body with a much larger fuselage volume for the wingspan?

Weight is the limiting factor as much as size though, as mentioned, consideration to paved surfaces and undercarriage. Also wake turbulence for following aircraft... not all aircraft will be anywhere near as big, and something so big will limit approach/departure flow.

Also handling ability, something so big will have a massive turnaround time, not only will boarding/disembarking take forever unless airports utilise more aircraft doors, but also the time spent cleaning/prepping the cabin between pax.

It appears to make more sense for smaller more efficient aircraft, which is why 787/A350 seem to be the future rather than 747/A380

Stanwell

7th Feb 2016, 15:17

I've often wondered why the blended wing/lifting body concept hasn't met with much favour.
Vincent Burnelli's lifting body designs (1920s to 1950s) seemed to offer significant advantages in terms of safety, comfort,
economics and operation over conventional designs.

Could somebody enlighten me as to why the 'tin tube' concept continues to dominate?

Tourist

7th Feb 2016, 15:28

Tubes are easy to make and handle pressurisation easily?

Wider is tricky to evacuate?

People like windows?

Runways are only so wide and its nice to have wheels wide relative to fuselage?

Sokol

7th Feb 2016, 15:56

Hi,

since HTMF:mad:U wiped out my explainful answer twice, all in very short manner:

Read through Ludwig Prandtl.
Galley won´t fit into wingbox.

Greetings,

Tourist

7th Feb 2016, 15:59

Oh go on. Sounds like you actually know what you are talking about.

Machinbird

7th Feb 2016, 16:05

Interesting concept.
To fly, you are going to need some angle of attack, aren't you?
How does it rotate with all those wheels in ground contact including some well behind the C.G.?
Likewise, how do you land it?

You might need a variable incidence wing like the F-8 Crusader had. Either that or a whole lot of trailing edge flap and no leading edge slats.

DirtyProp

7th Feb 2016, 16:11

I thought that there were some structural limits that dictate how big we can build something until it collapses under its own weight.
I'm not an engineer, so feel free to correct me....

Tourist

7th Feb 2016, 16:15

LlamaFarmer

7th Feb 2016, 16:41

I thought that there were some structural limits that dictate how big we can build something until it collapses under its own weight.
I'm not an engineer, so feel free to correct me....

Like a black hole?

Capot

7th Feb 2016, 17:05

Just another small point; when the B747 arrived, a number of airports struggled with the fact that their taxiways and parking stands were at a distance from the runway centre-line that meant a B747 tail fin would penetrate the obstacle limitation transitional surface while manoeuvering or on a stand. I don't remember the exact details, but it was a problem.

In your concept drawing the fin is 22.5m high, which I think is about 2.5m higher than a B747; maybe different variants had different heights.

All that shows is that trying to fit a revolutionary new aircraft into existing airport infrastructure is doomed to a degree of failure; fin penetration of the transitional surface is just one tiny detail.

If a team of engineers and designers were to take airport design and stand it on its head, imagine what they could come up with. It would take a decade or two to really change the industry globally as new aircraft design exploits the freedoms offered by a new generation of airports, and design changes must take transition into account, but it can and must be done.

Here's a starter; ever wondered why airport terminals exist? Is there any other way to design and operate an inter-modal hub; maybe doing away with private cars and taxis as a way of getting there or leaving, as well as forgetting any need to provide a shopping mall. If you start with a list of essential functions for the airport to provide, including 3000m of concrete runway, and put them together in a totally different way than is done at present, you begin to realise that there are better ways of doing it.

I'll go back to my previous remark in another post; is it not remarkable and shameful that 40 years after the introduction of the B747, and 50 years (I guess) since its design was first thought about, we are still building terminals that are so dysfunctional that while people can shop in them until they drop, when they board a B747, and get off it at the other end, they'll be lucky to do so through 2 doors instead of one. How utterly absurd is that?

Imagine building a railway station where to get off a train you need to walk down the whole length of it to get out through a single door, and vice versa to get on.

The challenge isn't to design new and better aircraft, it's to design a new and better airport system..

DirtyProp

7th Feb 2016, 17:10

Like a black hole?
Yes, that's it! Or was it a worm-hole...? :suspect:

Seriously, though.
Is there no limit to how big we can build those things?

Tourist

7th Feb 2016, 17:13

Seriously, though.
Is there no limit to how big we can build those things?

Yes, there is, and always has been.

That figure is constantly changing with engine/materials technology and I have no idea what it is at the moment.

I am quite sure that it is not the limiting factor in this case though.

Genghis the Engineer

7th Feb 2016, 17:15

Sokol

7th Feb 2016, 18:03

Is there no limit to how big we can build those things?

Sure there is: Firstly the budget, secondly the earth radius.

Oh go on. Sounds like you actually know what you are talking about.

Sorry, not this evening.

Greetings,

Tourist

7th Feb 2016, 18:05

I've not read his papers yet (in fact I don't think that they've been published), but gather on the professional grapevine that a well regarded professor at Cranfield is asking this very question at the moment.

He's apparently concluded that bigger airliners would be much more efficient, and that the limiting factor on airliner efficiency at the moment is the ICAO 80x80m box.

G

That's very interesting and I would be interested to read about it. It makes sense for various reasons.
I am under the impression that the A380 is less efficient than 777 in terms of fuel per mile per passenger though despite being bigger and newer..

Genghis the Engineer

7th Feb 2016, 18:25

I should keep an eye on Aeronautical Journal - that would be my best bet on where he'll publish.

G

LlamaFarmer

7th Feb 2016, 18:57

That's very interesting and I would be interested to read about it. It makes sense for various reasons.
I am under the impression that the A380 is less efficient than 777 in terms of fuel per mile per passenger though despite being bigger and newer..

According to wiki you would be correct.

http://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#Long_haul

Quick look on unverified websites for fuel cost confirms:

A380
$60.35 per nm
say 500 seats typical layout
$0.12 per nm per seat

B777
$38.99 per nm
350 typical
$0.11 per nm per seat

Never mind the vastly lower cost for the aircraft itself.

Probably why the A380 and B747 have been less popular of late with more orders for the wide-twins like the 777/787 and 330/350

Piltdown Man

9th Feb 2016, 13:59

The problem is not really how big the aircraft can be but more a case of how will the airport infrastructure cope? And then you have the human aspect. The weakest, most frail and unreliable things on an aircraft are passengers. Keep piling them on and after a while your HyperJumbo will be diverting all over the place because the buggers in the back keep popping their clogs. And then you have the marketing problem. Just how many people want to go from A to B? I am convinced that we are approaching saturation on some routes yet capacity keeps increasing. How long before the bloodbath? Do we need yet more capacity?

PM

AC560

9th Feb 2016, 14:31

To me the issue with getting bigger is how many massive planes are really needed in the marketplace for hub/hub movements. You have to sell so many aircraft to recoup the tooling and design costs. A good example is Concorde where operationally it made some sense but the marketplace was never large enough for the manufacturer to turn a profit. The A380 seems to be going the same direction (time will tell).

If you look at JFK<->UK and the number of flights there is no doubt that reducing to a couple A380's JFK<->LHR would be a lot cheaper as you would need less crew, ground, maintenance, etc. on the smaller fleet. The consumer though seems to prefer a lot more time slots and more point/point versus hub. Given the choice of flying 7hrs to LHR and then sitting around a couple of hours and connecting to MAN, I would prefer to pay more for a direct flight.

Sokol

9th Feb 2016, 15:20

Now i am done with reading the .pdf in the first Post.

My Summary: Short Prandtl without mentioning key facts, Aeroelastics- the only mention in this Article, Missing parts of Computed Analysis, Computer coded Darwin-without Darwin, induced Drag is not Suitable for "classic" layouts @ M0.8, Overwhelming Conlusion without criticism.

The most disturbing fact is that he mentioned Aeroelastics only once in the whole Paper but is planning to include an forward swept Wing(part).
Thats also a Point of Criticism in the Openers Post. It is nice to get extra stiffness from installing the upper Wing nearly directly onto the Airframe. There are 2 things to obtain about this:

Firstly you get all the loads of both Wings directly into the Airframe which causes high stress.
Secondly you get in serious trouble with the aft wing when the plane has to ditch, it would be better if this wing would fall off at thus moment without big issues to the hull.

Thats why all BW concepts have thier aft wings installed on the Tailrudder.

P.S. The Wingbox is a highly stressed Part as you can see from Above. It has to be monitored on an regular Basis, no one wants to dismantle half of the Cabin for that.

The right conclusion in the Paper is that BW is a great concept for regional Airliners. To complete this thesis, slow flying regional Airliners, maybe fitted with RR Propfans. (Transonic Airfoils not needed for that)

P.p.S it is funny to see that aircraft designers use firstly CFD and then Euler, especially from a turbine point of view.

Greetings,

medviation

9th Feb 2016, 15:38

On the argument of the Hyperjumbo's business case:

As I said, I'm not here to argue about the marketability of such aircraft in today's economic climate. I think the A380 is overkill for most airlines except Emirates who seem to never be satisfied with the size of their aircraft. I was just curious about how big we can build airplanes with today's technology and standards.

On the argument of how airports will cope with the aircraft:

This would depend from airport to airport and how airport authorities are willing to accept this aircraft, which I believe boils down to the market demand for this aircraft, which is not the aim of this analysis. If there's a sudden change in the economic climate and an aircraft this size will be in hot demand, I think airport authorities will be more than willing to take action.

Renovating (which airports do all the time anyway) to make bigger pre-departure halls, immigration stands, baggage claim areas, etc. is not going to "rewrite airport infrastructure rules". Maybe in today's most modern airports, the biggest modification they will make is adding a 4th jetway that can reach the 3rd deck and that's it.

Some good points pointed out:

1. Pavement strength. I'm not too familiar with airport pavement standards. Is there a way around this with more wheels perhaps? Or, different landing gear configuration? I know Airbus made a variant of the A320 with 4-wheel bogies instead of two for it to be able to operate in weaker pavements.

http://cdn-www.airliners.net/aviation-photos/middle/1/6/0/1656061.jpg

2. Human aspect. It maybe true this aircraft may experience more diversions due to emergencies involving passengers going crazy or other health reasons. Is there an acceptable number regarding this. If so, how can this be improved?

Also, with so many passengers, how can they evacuate in an emergency? With slides of course!

http://s18.postimg.org/d0atia0vt/hyperjumbo_evacuation.png

Airbus did a study (https://www.ipa.tu-berlin.de/fileadmin/i14/Personen/Jungermann/Publikationen/edinburgh.pdf) on how evacuation on the upper deck is compared to the lower deck. And the findings show that passengers on the upper deck may hesitate more. This could be a big blow to the design but we'll never know until more testing is conducted. Also the upper deck slides might need an upgrade to cope with the size. Possible solutions could be a slide design with taller handrails so exiting passengers feel more "cradled" upon sliding.

NSEU

10th Feb 2016, 00:25

AN225 is a bit like that with all it's rows of wheels.

How does the AN225 undercarriage cope with the weight on touchdown? Does it land with no pitch? I can see the rear undercarriage collapsing on this mega-jumbo on landing. All the weight will be on the rear wheels.

Apart from that, it looks like a maintenance nightmare. You would need several cherry pickers on every transit just to check the engines and top up the oil. By comparison, the inboard engines on a 747-400 with RB211 engines can be serviced without steps.

One of the reasons the 777 is so efficient is because maintenance engineers had an input into it's design. If an aircraft is easy to work on, turnaround times are faster and it's inherently safer. Airbus didn't quite grasp this concept with the A380.

I see half the fuel supply is below the height of the engines (not so good when "gravity" feed is required).

medviation

10th Feb 2016, 00:51

How does the AN225 undercarriage cope with the weight on touchdown? Does it land with no pitch? I can see the rear undercarriage collapsing on this mega-jumbo on landing. All the weight will be on the rear wheels.

I don't see the Antonov 225 having problems with it.

https://s-media-cache-ak0.pinimg.com/736x/5a/51/d7/5a51d77ecb9c036ae3230cdd689dc51a.jpg
http://cdn-www.airliners.net/aviation-photos/middle/5/1/4/1247415.jpg

As well as many other aircraft.

https://36.media.tumblr.com/tumblr_lxx3f99YtD1r188b9o1_500.jpg
http://s12.postimg.org/j072e5959/Image2.jpg

http://s28.postimg.org/a3gy2ynkd/Image4.jpg

Apart from that, it looks like a maintenance nightmare. You would need several cherry pickers on every transit just to check the engines and top up the oil. By comparison, the inboard engines on a 747-400 with RB211 engines can be serviced without steps.

One of the reasons the 777 is so efficient is because maintenance engineers had an input into it's design. If an aircraft is easy to work on, turnaround times are faster and it's inherently safer. Airbus didn't quite grasp this concept with the A380.

I see half the fuel supply is below the height of the engines (not so good when "gravity" feed is required).

Did it cause problems on the A380? And with the increased passengers, wouldn't the turnaround time be longer anyway. Can't engineers use that time to inspect whatever they need to inspect?

Sokol

10th Feb 2016, 13:16

I don't see the Antonov 225 having problems with it.

´cause the Antonov has its center of lift directly above the landing gear. Thus provides smaller loads on the aft wheels whilst landing.

Can't engineers use that time to inspect whatever they need to inspect?

They do. Because it is a more adequate way to reduce the turnaround time in the design itself instead of shortening the ground crews time.

Greetings,

medviation

10th Feb 2016, 13:41

´cause the Antonov has its center of lift directly above the landing gear. Thus provides smaller loads on the aft wheels whilst landing.

The center of lift of the hyperjumbo IS directly above the landing gear (resultant center of lift of both wings).

Just to clarify, the projected CG and center of lift characteristics of this aircraft is similar to that of an aft-mounted engine aircraft like the MD-80 because it's 6 engines are practically mounted aft. This is why the landing gears are moved back.

Also, I've modified the landing gear a bit. It now features 2 rows of wheels in each bogie compared to just one in the previous photos.

http://s8.postimg.org/k98v9pg7p/landing_gear_plan.png

No Fly Zone

10th Feb 2016, 14:16

There are likely only 3-4 RWYs in the world that can accommodate something this large, none of the where PAX really want to go. While it would probably fly, ground infrastructure is no where close of able to accept this plane. And who would want to fly on it? Not me!

Stanwell

10th Feb 2016, 14:54

From an SLF point of view, I don't think I'd like to be allocated, say, 37G on the middle deck.
But then, some people seem to get off on that sort of thing - for example, those that flock to football games and such.

A chap told us the other night that he liked travelling on the upper deck of the A380 - because the view is much better up there. (??)

Sokol

10th Feb 2016, 16:33

The center of lift of the hyperjumbo IS directly above the landing gear (resultant center of lift of both wings).

I got that Idea. But the center of lift has to move forward on landing since your rear wing is used as elevator.

Just to clarify, the projected CG and center of lift characteristics of this aircraft is similar to that of an aft-mounted engine aircraft like the MD-80 because it's 6 engines are practically mounted aft.

Thats clear. Like i said, an forward swept wing brings in Aeroelastic problems, the bigger the wings size the bigger the problem gets. Adding 6 engines onto that structure should size that problem to another level.

Your design looks futuristic but in my opinion it is more practical to use an (Beechcraft)Staggerwing like boxwing configuration with classic elevator and rudder.
This also provides chances of turbine driven E-fans.

Greetings,

medviation

10th Feb 2016, 19:46

I got that Idea. But the center of lift has to move forward on landing since your rear wing is used as elevator.

We may never know the exact weight/balance numbers but my model and similar real-life examples demonstrate the landing gear concept to be workable. Also, pitch control is not limited to the rear wing. Yes, you can decrease lift to the rear wing to pitch up, but you can also increase lift to the front to pitch up.

Thats clear. Like i said, an forward swept wing brings in Aeroelastic problems, the bigger the wings size the bigger the problem gets. Adding 6 engines onto that structure should size that problem to another level.

Except, it's not a simple cantilever swept-forward wing. The closed wing system should cancel out opposing forces on the two wings so as a whole, it should be as structurally sound as a very thick straight wing, without the increased drag.

Your design looks futuristic but in my opinion it is more practical to use an (Beechcraft)Staggerwing like boxwing configuration with classic elevator and rudder.
This also provides chances of turbine driven E-fans.

Thanks but why increase the weight by adding elevators when you can use the wings for pitch control? Compared to conventional design, the wings need to compensate for the negative lift the elevators are producing.

NSEU

10th Feb 2016, 21:02

Can't engineers use that time to inspect whatever they need to inspect?

Having operated a cherry picker myself (as part of my engineering duties), I can assure you you're going to increase the inspection/top up time by a factor of 10. I can check the oils and do "front and back" inspections on a 747 in the time it takes for me to put on a safety harness and park one cherry picker at the aircraft. The presence of 2 or more cherry pickers around an aircraft would also interfere with cargo loading.

And no airline is going to wear the costs of 2 cherry pickers per aircraft (I think we only had one or two for the entire fleet at our main base).

(EDIT: Beancounters are also continually telling us that "time on the ground" is wasted. Surely the ultimate goal would be to have shorter transit times. Additional time spent on routine servicing means less time for working on non-routine problems)

I don't see the Antonov 225 having problems with it. As well as many other aircraft.

Point taken. I wonder if the main gear elements are identical on the Antonov or if there are additional reinforcements for the rear gear. The 747 wing gear does seem more robust than the wing gear. The 777 is not really a valid argument. The bogey tilt accommodates the pitch angle.

Intruder

10th Feb 2016, 21:31

I suspect your limitations will include individual tire load and speed limits. it would be fiscally untenable for an airline to have to buy a unique tire for a low-production airplane. OTOH, if you can put enough wheels on it...

Also, I think a blended wing-body concept would fare better than a conventional fuselage+wing design for something that large.

All those considerations are beyond the "need" for an airplane larger than the 747 or A380 in the first place...

Jonno_aus

11th Feb 2016, 03:47

From an SLF point of view, I don't think I'd like to be allocated, say, 37G on the middle deck.
But then, some people seem to get off on that sort of thing - for example, those that flock to football games and such.

Looking at the design, it would be easy to see that sitting in the vicinity of 37G is where the partying would be. First seat sold I'd say.

What's the fascination with size? Has everyone now forgotten speed? Is it for the too hard basket? Because when I fly from SYD to LAX, sitting for 13-14 hours gives me the :mad: . I want it to only be a '3 movie' flight at best.

That's what people want. Speed. The talk around the water coolers at work isn't about big aircraft. It's talk of fast aircraft. That's what us punters want. Fast sonsofbitches to get us there quick.

Impressive engineering skills though, for that aircraft. Stick another 6 engines on the sucker and THEN we'll talkin!!! :ok:

Sokol

11th Feb 2016, 10:01

Also, pitch control is not limited to the rear wing. Yes, you can decrease lift to the rear wing to pitch up, but you can also increase lift to the front to pitch up.It is completely anyhow how you do the pitch up in this configuration. It does result in a higher lift in the front wing, so the neutral point moves forward.

We may never know the exact weight/balance numbers but my model and similar real-life examples demonstrate the landing gear concept to be workable.

Thats true. Mainly on Transport Aircrafts.

Except, it's not a simple cantilever swept-forward wing. The closed wing system should cancel out opposing forces on the two wings so as a whole, it should be as structurally sound as a very thick straight wing, without the increased drag.As you may read in the paper: The wingtips are heavily loaded parts of the structure only after an Aerodynamic evaluation. Aeroelastic evaluation wasn´t done until that point.
Concluding: The Wingtips may get heavier than planned which means a loss in capacy (and an increase in maintenance costs).

Compared to conventional design, the wings need to compensate for the negative lift the elevators are producing. Not on the conventional design. The Wings have to compensate the angle of attack induced by the elevators, the center of lift (nearly) stays fixed in this configuration.

Thanks but why increase the weight by adding elevators when you can use the wings for pitch control? As seen from above.

P.S.: If you want an futuristic and stable design with elevators at this size:
Try an P.180 layout with both wings swept forward, engines between the wings (fixed on upper and lower) providing extra stiffness.

That's what people want. Speed. The talk around the water coolers at work isn't about big aircraft. It's talk of fast aircraft. That's what us punters want. Fast sonsofbitches to get us there quick. Thats true. Just adding engines wouldn´t do that thing. Have you already read about SABRE engines?

Greetings,

Tourist

11th Feb 2016, 10:48

.
That's what people want. Speed. The talk around the water coolers at work isn't about big aircraft. It's talk of fast aircraft. That's what us punters want. Fast sonsofbitches to get us there quick.

The evidence suggests that the opposite is true.
Since the 70s airliners have got a lot slower.
Airlines noticed that passengers are upset by being late, not slow. They then increased all the scheduled times so that if delayed the aircraft could speed up from the usual economical cruise to catch up. VC10 was a rocket ship compared to current airliners.

Incidentally, who among you even knows which airliners are the fastest? Surely if it actually mattered people would chose to fly on the fast ones?

Derfred

11th Feb 2016, 12:17

Can a closed wing design such as this achieve positive longitudinal static stability?

I recall a certain ultralight with a similar wing, which crashed a lot.

Stanwell

11th Feb 2016, 12:27

Ligeti's Stratos?

Owain Glyndwr

11th Feb 2016, 16:28

I have been a fully paid up member of the RAeS for over sixty years, but as I don't want to be accused of nit-picking (post#8) I will refrain from any direct comment on the HyperJumbo as presented and confine myself to remarks on the general concept.
The box-wing has been around for a long time and although the details differ the HyperJumbo under discussion has noticeable similarities to the 1995 Lockheed Boxwing.

https://photos-1.dropbox.com/t/2/AADSbK2nVS3Eeol6x73QWFlBWI80DUYWEhFM0G9Egq4a3w/12/384260522/jpeg/32x32/1/_/1/2/2016-02-10_113357.jpg/EPTGr4cDGBAgASgB/VbOq7VSJWSOMr4mslWDW97jxNDAb6NRDG4YWILvblj8?size=1280x960&size_mode=3

This latter was put together by a professional design team so we can assume it to have been properly thought through. It was assessed by a NASA/Boeing/Stanford group as having achieved the minimum theoretical vortex drag in a configuration with "reasonable" high speed performance (it had favourable transonic area ruling) and some structural advantages.
The problem areas identified, but not resolved, included landing gear integration, maximum lift penalties, fuel volume and low sectional Reynolds Numbers.

The general concept of drag reduction by use of non-planar wings has been studied in detail by Prof. Ilan Kroo of Stanford University. There are a couple of papers worth reading if you want more detail.
Highly Nonplanar Lifting Systems: Ilan Kroo, Stanford University; John McMasters, Boeing Commercial Airplane Group, and Stephen C. Smith, NASA Ames Research Center: Transportation Beyond 2000: Technologies Needed for Engineering Design: September 26-28, 1995
Nonplanar wing concepts for increased aircraft efficiency. I Kroo Stanford University USA; VKI lecture series on Innovative Configurations and Advanced Concepts for Future Civil Aircraft. June 6-10, 2005
The more important conclusions are summarised on the following chart, extracted from one of those papers.

https://photos-4.dropbox.com/t/2/AABrWoh9gh97pP4PMFaZoX-O8Zd1OJU-EFD8hm7iiLVxzA/12/384260522/jpeg/32x32/1/_/1/2/Span%20efficiency%20nonplanar%20wings.jpg/EPTGr4cDGBAgASgB/qw7YRGPOxtI0vhGSc988b3fFqFwn21PC-cdXU0Hmrv0?size_mode=3&size=1280x960

Down on the bottom right Configuration "A" is the closed wing arrangement proposed for the HyperJumbo. It offers the maximum reduction in theoretical vortex drag.
However, Kroo established that you do not need to close the wing to get this drag reduction. Configuration "C" has pretty well the same drag reduction but without the problems associated with the complete boxwing. Kroo developed this thinking into a "C wing" design as shown.

https://photos-3.dropbox.com/t/2/AADsmnhp17dW5jhxr6Tr06T6UOXQ2BJfFMGptIfnEZVxvg/12/384260522/jpeg/32x32/1/_/1/2/Blended%20C%20wing.jpg/EPTGr4cDGBAgASgB/tRlUrJvhEuBo9-34W2mwSg4jtl0KxQCfnOaEKUnbT_4?size_mode=3&size=1280x960

You may, or may not be a convert of the blended wing philosophy, but it does look plausible.

Before getting too excited it might be worthwhile reflecting that the drag reductions being claimed relate to the theoretical vortex drag; that is to the inviscid drag produced by the particular distribution of vorticity over the wing. This theoretical vortex drag is a large part of the total drag due to lift, but is by no means the whole of it.
Staying with the American practice of using Oswald efficiency to describe induced drag, the Oswald efficiency of a modern wing in cruise is of the order 0.8. The theoretical vortex drag contribution would be around 0.9 to 0.93, the rest comes from lift (or aoa) sensitive viscous flow effects giving rise to minor flow separations which in turn produce drag.
Until we know how these viscous effects will operate on unconventional configurations such as the Hyperjumbo we cannot be sure how much of the theoretical drag gains will actually be achieved.
Note also that modern wings are NOT designed to cruise with the theoretically optimum vortex drag. The objective is to produce the best wing not simply the most aerodynamically efficient. It generally pays to back off the theoretical optimum, have a span loading with a more inboard centre of pressure than an elliptic loading and cash the weight saving. That is without winglets of course.
This general thought must be carried over to any new proposals - the object is the best overall design not necessarily the most aerodynamically efficient.
Go back to the second chart and consider Configuration "B". This has less potential gain than A or C but it is a much simpler arrangement. In fact the reduction in theoretical vortex drag is 90% of the theoretical maximum reduction, but the only change to a planar wing is the addition of Longhorn style vertical winglets.
Now if, and it is a very big IF, a viable market emerges for an aircraft with more capacity than be squeezed out of an A380, would you tear up everything and go for an untried unconventional layout or would you chicken out and adopt a simple vertical winglet modification to the A380 for slightly lower potential gains but much less commercial risk?

PS I have just discovered that the illustrations may not appear. They were OK on my PC but not on the ipad. I seem to have a problem with Dropbox which I will attempt to sort out. Meantime, if anyone is desperate to see the pictures they are lifted directly from the two papers I cited. For the first illustration see the Kroo/McMasters/Smith paper p338, for the second see the same paper p346 or p 353, or a slightly different presentation in the Kroo paper Fig 18 (p.18) and for the third illustration see the Kroo paper Fig 13 (p. 15)

All-Ex

14th Feb 2016, 15:53

But I wasn't too familiar with airport pavement design. I thought if I added more wheels the distribution of weight will be spread out similar to an A380 or 747. Could you share some numbers?You will find tons of information regarding the A380 in this document:

A380 AIRCRAFT CHARACTERISTICS AIRPORT AND MAINTENANCE PLANNING:
http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC-A380-Dec2014.pdf

Since you want to design you aircraft to the same restrictions as an A380 has the document might apply to your design as well.

RVF750

14th Feb 2016, 16:29

I agree on earlier posts that the limit is the airport designs.

I have always marvelled at the inefficiency of nose in parking. Once during apron works we had to park side on, and de-boarding/boarding all happened quicker with two sets of steps equidistant from the gate entrance. Bags were kept away from the passengers too.

A properly designed pier system with underground passages for service vehicles and provision to connect airbridges front AND rear would allow aircraft like the B777, A380 and B747 turn quicker. Smaller aircraft would benefit even more as they are not limited to the constraints of the larger long haul ships, slots and spacing to enable two flight daily cycles, etc.

Just a thought.

SeenItAll

14th Feb 2016, 20:15

Imaginative design. It shows a lot of work and thought. But my concern is as a passenger. The five- and six-across middle rows look like a nightmare. I don't see how it is going to work with just two aisles -- unless they are double-wide so that at least two people can pass simultaneously. Think of the extra time to load the plane as people already seated need to get up and enter the aisle to let later-arriving middle seat passengers get in. Also, I think evacuation would present a problem.

medviation

15th Feb 2016, 08:34

You will find tons of information regarding the A380 in this document:

A380 AIRCRAFT CHARACTERISTICS AIRPORT AND MAINTENANCE PLANNING:
http://www.airbus.com/fileadmin/medi...80-Dec2014.pdf (http://www.airbus.com/fileadmin/media_gallery/files/tech_data/AC/Airbus-AC-A380-Dec2014.pdf)

Since you want to design you aircraft to the same restrictions as an A380 has the document might apply to your design as well.

Thanks! That's quite a useful document there! :)

I agree on earlier posts that the limit is the airport designs.

I have always marvelled at the inefficiency of nose in parking. Once during apron works we had to park side on, and de-boarding/boarding all happened quicker with two sets of steps equidistant from the gate entrance. Bags were kept away from the passengers too.

A properly designed pier system with underground passages for service vehicles and provision to connect airbridges front AND rear would allow aircraft like the B777, A380 and B747 turn quicker. Smaller aircraft would benefit even more as they are not limited to the constraints of the larger long haul ships, slots and spacing to enable two flight daily cycles, etc.

Just a thought.

I agree too. Personally I think the future would be about both size and efficiency. And with that comes along gradual airport innovations as well.

Imaginative design. It shows a lot of work and thought. But my concern is as a passenger. The five- and six-across middle rows look like a nightmare. I don't see how it is going to work with just two aisles -- unless they are double-wide so that at least two people can pass simultaneously. Think of the extra time to load the plane as people already seated need to get up and enter the aisle to let later-arriving middle seat passengers get in. Also, I think evacuation would present a problem.

Thanks. 5 middle row seats already exist (see DC-10/MD-11, B777, and soon the A380). 6 middle row seats though are new territories for airlines. I don't see why not when it's practically two A320/737s side by side. But I would expect most airlines would choose 5 middle row seats though over 6 for a total of 11 abreast. I just showed that 12 abreast is possible with 17.5in seats and 15in aisles.

I'm confident evacuation wouldn't be a problem since I configured my aircraft with sufficient exits per deck. The aircraft would have 4 pairs of type A doors on the upper deck, 5 on the main deck and 6 on the lower deck. Each pair of type A door is allowed 110 passengers and I have 15 pairs for a total of 1650 allowable pax capacity. Each exit is within the 60ft separation limit and spaced almost evenly throughout the fuselage.

This is why I chose box wing design over blended wing body. A blended wing body would force you to have exits spaced more than 60ft. And if you put exit openings at the belly, it would be difficult if you have a landing gear collapse. This would need a lot of convincing to the FAA to certify.

Anyway, I have been playing around cabin configurations. Some standard features unique to this aircraft is the forward atrium and mezzanine on the main and upper deck. Since the fuselage curves downward at the nose, the "forehead" would be impractical to fill with galleys and seats, so I decided to leave it empty. Premium airlines can use that space for an ultra-luxurious first/business class lounge or potential for two loft-type suites (a-la Etihad Residence but on steroids). There will also be a lift (option for two) that can carry people and trolleys across the three decks. There will also be two staircases. One in the front, one at the back. Here are some preliminary studies I've came up with:

Ultra dense: Maximum possible configuration. Lavs and galleys of the lower deck are transferred to the main deck so this configuration might only be seen on military or special ops versions.

http://s10.postimg.org/cdsrl0pop/I11_A_presentation_1650_ultra_dense.png

Dense: We might see this configuration for long-haul LCCs or holiday charter airlines.

http://s12.postimg.org/uvucx10zx/I11_A_presentation_1586_high_density.png

Standard single class: This would probably serve as the basis of most configurations for major airline customers out there. This shows the second lift at the back.

http://s14.postimg.org/xkvd87zgh/I11_A_presentation_1316_single_class_v2.png

I'll post 2-class and 3-class and more soon!

glum

15th Feb 2016, 12:52

have you seen the Cranfield study of 2010?

https://www.youtube.com/watch?v=8ojMUAEj-ho

SeenItAll

15th Feb 2016, 14:21

I agree that initially, standard seating on the DC-10 and B777 was 2-5-2. But the DC-10 went away, and seating on the B777 has generally changed to 3-3-3 (or 3-4-3, a configuration that I avoid like the plague).

I still believe that despite a huge increase in emergency exit doors, you will still need double-wide aisles in order to have efficient PAX loading and unloading, as well as avoiding complete aisle blockage by service trolleys.

medviation

15th Feb 2016, 20:20

have you seen the Cranfield study of 2010?

https://www.youtube.com/watch?v=8ojMUAEj-ho

Thanks for sharing!

I agree that initially, standard seating on the DC-10 and B777 was 2-5-2. But the DC-10 went away, and seating on the B777 has generally changed to 3-3-3 (or 3-4-3, a configuration that I avoid like the plague).

I still believe that despite a huge increase in emergency exit doors, you will still need double-wide aisles in order to have efficient PAX loading and unloading, as well as avoiding complete aisle blockage by service trolleys.

Yeah, that's a personal preference of aviation guys like us. But for most people who just want to fly for cheap, they don't care much if it's a 2-5-2 or 3-3-3 or 3-4-3. At 18in 11-abreast, that's as wide as standard economy gets. If you want more, go for premium econ or business class.

Maybe increased aisle width, yes. But double aisle width is I think overkill. Each deck is about the size of your average B777-300 so I don't see why double-width aisles are necessary. And at 11-abreast (lower and main deck), 26in width each aisle is available.

OFF TOPIC: Doesn't forums have quote buttons so you can show the name of the person you are quoting?

Sokol

15th Feb 2016, 21:18

I'm confident evacuation wouldn't be a problem since I configured my aircraft with sufficient exits per deck. The aircraft would have 4 pairs of type A doors on the upper deck, 5 on the main deck and 6 on the lower deck.[...]

Do you have any clue how that plus the long distance between the wings would influence the structural analysis?

Even though: An aircraft is not an flying house, there is a reason that the evacuation is live tested for certification.

If you want more, go for premium econ or business class.

Throw the caviar onto the streets, that the mob would slip on it and breaks its neck.(Sorry sarcasm is a side effect of engineers)

OFF TOPIC: Doesn't forums have quote buttons so you can show the name of the person you are quoting? Try HTML sometimes.

Greetings,

medviation

15th Feb 2016, 21:41

Do you have any clue how that plus the long distance between the wings would influence the structural analysis?

No I don't have a clue. I'm just a scruffy guy with no engineering or flying experience who hides in his room most of the day. I'm bringing this up for help with the analysis.

Even though: An aircraft is not a flying house, there is a reason that the evacuation is live tested for certification.

That may be. Since this aircraft may never get built, live testing is out of the question. I was at least referring to this: FAA Part 25.807 (http://flightsimaviation.com/data/FARS/part_25-807.html)

Sokol

16th Feb 2016, 11:51

No I don't have a clue. I'm just a scruffy guy with no engineering or flying experience who hides in his room most of the day. I'm bringing this up for help with the analysis.

Then crash course in german engineering 101:

When you discuss an idea, it is not the person under criticism, it is the idea.
If you get a tip about an limitation you have to change it, or set an IF.
e.g.: IF the neutral point stays within the limits whilst using pitch.
Too many IFs are pushing the project from hard to manage to science fiction.

As I already said, it is mainly the distance between the fixpoints of the wings that gets this project to Science fiction. With this layout the project gets the following IFs:

IF the structural analysis is sober with consideration of turbulences,
IF the neutral point of lift stays within the limits,
IF the aeroelastic layout is done properly or new meterials appear,
IF someone needs an newly designed aircraft with the capacy of 2 A380s,
IF the airports get to manage the newly type of aircraft,

the plane could be built.

As you may have seen, even the Cranfield study has not this much space between the wings, you should think a bit of it. I mentioned already that aeroelastics may be a lot of a problem, this layout might work in a wingspan from 20-30 meters, 80 meters is sheer to much bravery.

Greetings,

glum

16th Feb 2016, 11:59

What is the drawback of having a dual wing layout like a traditional Biplane?

If wing length is the issue, then why not put half the wing directly on top of the other half, possibly joining the two wingtips to reduce the vortex effects?

Sallyann1234

16th Feb 2016, 21:45

I can just imagine the fun finding HOTAC for 1,600 pax in the event of a delayed/diverted/cancelled flight.

flynerd

16th Feb 2016, 22:04

I can just imagine the fun finding HOTAC for 1,600 pax in the event of a delayed/diverted/cancelled flight.

Easy. Airline provides just 1 service desk. Then as each person takes around 5 minutes to deal with = 12 per hour... 1600/12 = 133 hours to handle the queue.

Then, you have 5 days to work through the queue. After 24 hours, those at the head of the queue will be checking out and those rooms can be re-allocated.
Thus only about 320 rooms are needed.

medviation

17th Feb 2016, 00:37

I did a simple wingflex model to see how the wing would flex. I saw several issues with the bending motion especially on the wing brace that joins the two wings. Constant and extreme bending and twisting of the brace could lead to eventual failure of the wing structure if made of conventional aluminum or composite materials and structure.

http://s29.postimg.org/k2uhjewfb/wingflex.png

Having a background in architecture, I know of a technology used for earthquake-proofing buildings that could be applied here. This plastic/rubber bearing isolates the building from the foundation so when an earthquake occurs, the building can just dance around and not crack.

http://www.ibec.or.jp/jsbd/img/AR/g_08.jpg

A similar setup can be used to isolate the wingtip brace from the rest of the wings. This should allow the two wings to twist and bend without having to put too much pressure on the wingtip. This could be engineered to still have a certain amount of resistance so the two wings can still share loads.

Another area I might put in question is how this could react in flutter. Perhaps the two wings could be designed to oscillate in a different frequency to dampen out potentially dangerous vibrations? :confused: