Future Airliner design - will it really change?

I'd say that chances of the tube+wings airliner shape, so successfully established in the jet age by the 707, are maybe evens, at best, to pretty slim.

Among the reasons for this are the issue surrounding evacuation times, as raised already in the 797 thread, there is also an elegant simplicity to the layout which explains why you can buy an A340 today that looks pretty similar in general arrangement to the 707 of half a century earlier. Go back a further half century and you are into Wright Brothers territory!

Having the engines hung under the wings on pylons is known to be less favourable than the rear mounted layout which was pioneered by France with its Caravelle. This layout was openly mocked when the Caravelle was first revealed, yet it was quickly copied by the UK, with the BAC One Eleven, and America, with the DC-9.

The advantages of rear mounted engines include a reduced likliehood of FOD, a quieter passenger cabin and a more aerodynamically efficient wing. Despite that last one, when Boeing designed the 787 they STILL opted to mount the engines under the wings, even though its raison d’etre is efficiency.

Disadvantages are mainly centred around engineering and maintainance reasons with the engines being more inaccessible than ones close to the ground. Another disadvantage is the deep stall problem associated with mounting the tailplane at the top of the fin, however this was a self inflicted one by the British and American designers of rear engined aircraft, it was not something that the Caravelle suffered from with is cruciform tail of similar design to the Hawker Hunter.

Caravelle


Interestingly ALL the advantages and disadvantages mentioned above also apply to the Boeing and Airbus BWB designs. If the layout has been disowned by designers of conventional airliners why should it be any different for these two marvellous new concepts? As far as I am aware the only new airliner designed with rear engines is the Tu 334.

Here are some examples of advanced concepts for conventional (ie non SST) airliners;

It is quite unlikely that any of them will ever appear, but it illustrates the sort of ideas being bandied about to try and find that elusive design breakthrough.

Boeing BWB


Airbus Flying Wing


Both these designs, although different in detail, explore essentially identical concepts and are both aimed at accommodating around 1,000 passengers. Airbus considers this a potential replacement for the A380 in 20 or so years time, though this decision would clearly be influenced by what Boeing does with theirs.

In both designs the wing and fuselage are combined into a single, light weight, efficient structure. If a clean airflow can be achieved then radically reduced fuel consumption is the prize that awaits.

A drawback, however, is the limited scope for modification of a flying wing from a technical viewpoint: whereas a conventional aircraft type can simply be "stretched", it is likely that every model of a flying wing aircraft, and every size of every model, would require a dedicated design, with the associated cost implications. Due to the complex structure, it would not be possible to insert or remove segments of the fuselage

Airbus Joined Wing


The aerodynamics of this concept are said to be particularly complex. It is of course very much reminiscent of an advanced tanker concept that was designed by Lockheed at around the same time. Lest anyone think that Airbus merely copied Lockheed, it should be noted that this wing concept has been around since the 1930’s.

The primary objective of this concept is to achieve a significant reduction in the size and structural weight of the wing. The design would only need a very short span, which would be advantageous when manoeuvring on the ground. The joined wing would inevitably generate more drag than a conventional wing however, but the aim of the study was to see if all the other advantages could overcome this and result in an overall increased fuel efficiency.

Also, the raised upper fuselage line is aimed purely at reducing interference between the wings but it could also provide space for hydrogen fuels if such development should ever bear fruit.

Airbus ‘Three Surface Layout’


Essentially this concept equates to a canard equipped A340, though if produced its actual design would have be at least as efficient and advanced as the 787 of course. This design is said to be naturally unstable and with it Airbus was attempting to save weight by reducing the size of the rear stabiliser. It is also considered that its various tr8imming possibilities will result in improved cruise efficiency and thus reduced fuel burn. Another consideration is that for further developed stretch of high gross weight versions the overall lift can be increased by enlarging the canard surfaces rather than increasing the wingspan.

Note also how both preceding designs still use wing mounted underslung engines despite the quest for low noise and low fuel burn that inspired them.

Despite all of the above it is my belief that there will be no commercial launch for any of the concepts we have seen here and the best they can hope for is that these concepts lead to technological advances that can be built into aircraft which outwardly look just the same as jetliners always have, just like is happening now with the 787.




[edit on 25-4-2006 by waynos]

Great thread Waynos, as usual. I've always liked the tail mounted engines, simply because they're quiet. The underwing design though I always found so much easier to work on. It's nice being able to access the engine without having to climb up on a stand or a ladder.

Originally posted by waynos
Future Airliner design - will it really change?

I´d say not in the near future. Airliners have long reached a tech plateau, we´re at a point where new concepts in the end dont offer enough advantages to put up the effort and change the tried-and-proven system (something that is quite regular, for example ships, trains or cars havent changed decisively for decades, either). The vast regulations aircraft and the whole aero business are subordinate to doesnt make a radical design changes easier, either. As a saying in my country goes, "the mills of public agencies grind slowly" ...

For Aircraft aficionados, there are two things to hope for: either a groundbreaking new technology (for example new materials or new propulsion technique) and/or the negative impact of increasing oil prices. Both would be a strong lever to rethink almost every technical standard we have today.

OTOH one has to question whether all these concepts that may sound nice on paper are really feasible or would really offer the advantages they have in theory. One would think that at least one of the vast array of radical wing designs would have come to fruition if they were really THAT great. Personally, I think the impossibility of a new concept rises squared to the announced performance increase. When I read things like "25% more cost-efficient", I simply cant believe it. We are still cooking with water here

I think rear mounted engines will make a comeback with the rise of sustained trans/supersonic flight. The easiest way to ensure reliability being to design them as complete plug and play systems which large gantries can remove as a complete power pod for inspection and repair long after the (pretuned) replacement is mounted and the subject aircraft gone from the maintenance hangar.

That said, I have an awfully hard time, looking at the frontal area and spanwise distribution of the BWB, believing in anything like airliner performance of today being efficiently achieved.

Maybe lower down. As a WIG or other, sub-300 knot, 'flyup' platform. Even in specialist missions with VTOL as a primary driver. But the one thing you can say about mailtubes with wings is that they simplify greatly the aerodynamics and scaling issues as well as the engineering ones mentioned.

What interests me more is the notion of composite design enabling 'flipside' significant changes to airliners with an emphasis towards putting the wings HIGH and either suspending aft (canard/joined wing layout) engines. Or integrating them within a reverse lifting body shape that incorporates integral inlets to increase ramp performance in SS flight and allows for general improvements in static margin trim factors.

This approach also keeps the passenger view and potential emergency disembarkation options cleaner, lowers the gear stance and weight considerably and simplifies the airfoil:fuselage join even if it doesn't allow for the entire fuselage itself to be hardback suspended from beneath a monolithic wing structure.

I also wonder if, with systems like the HITS and ESTOL/Moller, we might not be seeing the end of an era in which large scale air transport really works at the higher economic class levels. It is certainly hard to put 4-10 people 500-800nm downrange at 25-28mpg within an airline level of scaling and _absolute efficiencies_ of fuel use over time may come to mean quite a bit as we burn down towards nothing on petroleum.

Even as, especially if there is a nuclear event or for whatever other reason, maintenance of local (ground) transport infrastructure net becomes difficult.

Which means that airline travel itself may have to be looked at as an expensive appendix for intracontinental service especially. And one which 'the masses' may not be able to support at ever increasing fuel prices. As they might say, supertrains or some other alternative system.

$$$$ recovery will drive investment. But technology will be adopted that reflects more than simple direct seat-mile seating gains. If we are at all wise.


KPl.

I personally think that as fuel prices rise, the push to find more efficient designs will push them towards Vacuum-cell Aerostat technology. Nearly neutrally boyant airframes are the future IMHO.

What are the advantages of Vacuum-Cell technology? Well for one thing, you can make it in any shape you require so it doesn't have the disadvantages of regular helium filled aerostats.

The main reason for the cylinder with wings shape being so popular is mainly that its understood. To obtain certification for a BWB or a similarly radical concept is a nightmare, and would be simply too much of a risk to take for a private company.


Regarding the engines - noise will become less of an issue as flight numbers reduce due to slowing economys as the oil price rises hit home. Efficiency and replacing petroleum will become the key areas of development. We could see a return to propfan reasearch (Gunston has stated propfans compared to the then modern 767 had half the sfc in cruise). The problem is they are really noisy. Or hydrogen power as I mentioned in another thread.


Structurally as well, a cylinder is great for pressure containment, but a BWB would be better for wing spar loading.




There is an aircraft which is a halfway house of sorts, the russian Dolphin/Dauphin aircraft. Very hard to come by internet links, but I found some of the stuff done by fellas in my undergrad class:

homepage.ntlworld.com...

Its a much more 'conventional' step to take compared to a BWB.


But tradeoff studies have been done for work more advanced than the above, and the conventional configuration comes out well ahead - mainly due to costs though - these are associated with the risk I mentioned earlier. In terms of performance, the Dolphin concept is well ahead, with the fuselage generated lift meaning much less complicated wings are needed (no leading edge slats and less flaps).

However, one thing that was found, with the wider fuselage, it could get the standard large containers used on big jets (LD-2,3,6,8 & 10) in, so would have been a good machine for a hub and spoke cargo distribution network. [good for a 70 seater jet ]

The fuselage required a double (or maybe treble depending on the width) 'bubble' construction, which, while not wholly ideal, is not too too bad weight wise. It actually compared favourably with the single bubble used in the dolphin, preliminary calcs putting the structure around 10-15 kg/m lighter.

Great job... Can we expect anything else...??

I love the Airbus Joined Wing model... It has no weaknesses, creating better lift right...??

Imo, if the oil shock continues 70% to 90% of airlines will go under, and the window from 1960 - 2010 will be seen as a golden era of cheap easy international air travel. I don't believe there will be advances in aircraft design until the military releases some of their exotic stuff which may allow some form of cheap international air travel to occur. In the interim there could be greatly reduced international air travel and an increase in domestic maglev train systems. Things might pick up again in 50 years or so.





[edit on 26-4-2006 by JamesinOz]

Originally posted by JamesinOz
Imo, if the oil shock continues 70% to 90% of airlines will go under, and the window from 1960 - 2010 will be seen as a golden era of cheap easy international air travel. I don't believe there will be advances in aircraft design until the military releases some of their exotic stuff that might allow some form of cheap international air transport to occur. In the interim their could be greatly reduced international air travel and an increase in domestic maglev train systems. Things might pick up again in 50 years or so.

I was of the same opinion, until I seen the preliminary work on hydrogen powered systems. I don't think it will be too bad. A 20% rise in DOC is not too bad.


What will affect the airlines more is that the world economy will be up the spout, so few would have the money to travel anyway (even if the flights continued at current prices).

Originally posted by JamesinOz
Imo, if the oil shock continues 70% to 90% of airlines will go under, and the window from 1960 - 2010 will be seen as a golden era of cheap easy international air travel. I don't believe there will be advances in aircraft design until the military releases some of their exotic stuff that might allow some form of cheap international air transport to occur. In the interim there could be greatly reduced international air travel and an increase in domestic maglev train systems. Things might pick up again in 50 years or so.

[edit on 25-4-2006 by JamesinOz]

With the price of oil, why not consider using train for the mainland (there must be lot of travel within the USA or Europe (train is more establish over there), a train like the Fench TGV (Train Grande Vitesse) give you almost the same speed (if you factor the waiting time at the airport, etc., etc. + the comfort is superior, have you heard Airbus is considering a STANDING UP section for short travel).

For international air travel, perhaps develop a better Russian like aircraft skimming over the ocean surface (it is 4 time more efficient than a 747).

A fundamental problem with rear mounted engines (and one that Boeing designed a remedy for on the B727) is the significant out of trim (nose heavy) condition caused by an engine departing the aircraft. On the 727, the nose up trim range was incredible (I don't remember the number of units) and only accounted for the loss of a single engine. The aircraft would be unflyable if two or more engines departed. But I am unaware of any engine departing from a 727, DC9, or MD80.

I love the 727 and often wondered why Boeing never returned to its design and installed two high-bypass engines (CFM56) in place of the 3. It had a relative high cruise speed and because of the sweep of its wings, was an efficient design. It was the fact that it had three engines that made it so inneficient.

Just stumbled across this at work. Sounds kind of funny, so have to dig deeper to see if it is true or not. Wouldn't be the first time a newspaper (especially an Australian one) got hoaxed by the internet. If true, well, I'd be interested in the restraining mechanism. High grade velcro maybe

Stand up and prepare for take-off

Freedom for sum, thats a good point and one that I overlooked in my first post, would I be right in thinking that the 727 and Hawker Siddeley Trident both used a variable pitch tail to counter this?

I love the 727 and often wondered why Boeing never returned to its design and installed two high-bypass engines (CFM56) in place of the 3.

That was how the 757 came about Here is a 1979 model of the 757 that Boeing touted to British Airways, it still has the 727 nose and tail, BA got the tail redesigned and later on Boeing changed the nose to one that had more commonality with the 767.




Wandering slightly, it has always fascinated my how the Hawker Siddely Trident, which inspired the 727 after the Boeing visit to Hatfield in 1958, underwent the exact same transformation as the 727/757 evolution when it was redesigned into the HS 134, namely it grew a longer fuselage and adopted a low tail and twin underwing high bypass engines. The thing is that the HS134 was designed in 1966, 13 years earlier than the Boeing model illustrated above.

But obviously it was British and so was never pursued due to Govt policy of the time. Their ideas may not be completely original but at least Boeing gets things done.

[edit on 26-4-2006 by waynos]

Originally posted by Willard856
Just stumbled across this at work. Sounds kind of funny, so have to dig deeper to see if it is true or not. Wouldn't be the first time a newspaper (especially an Australian one) got hoaxed by the internet. If true, well, I'd be interested in the restraining mechanism. High grade velcro maybe

Stand up and prepare for take-off

Yes, it is true

This is only an early simulator mock-up, I have also seen a more polished version (with a 3/4-point seatbelt, so possibly even more secure than a regular seat). It is however very difficult to find information about it, I guess they keep silent about it because of the negative public reaction when the design study was first revealed (and it really only was a design study back then, not an actual plan).

It´s not a real "standing" seat, it has a height-adjustable bycicle-like seat and the backboard is slightly angled backwards. I think it shouldnt be too uncomfortable on a short-haul flight (which it was designed for). Personally I like the idea, as I dont like to sit all the time during flights anyway, and it could greatly reduce the ticket price as well as increase the fuel-per-passenger-per-mile significantly.

Hmmm, don't like that idea AT ALL. I hope nobody goes for it.

couple of points, The implication in the piece that this is what 'Airbus wants', while Boeing is offering beds, betrays a clear overtone, precisely because it fails to mention the comfort lounges etc that have been shown in relation to the A380 (which have equally little hope of adoption) and that this would only happen if airlines wanted it, and if they did want it Boeing would offer the same.

Also, it is stated that this is aimed solely at island hopping style short haul flights, so why does the piece then go on to mention this being adopted for flights to Australia

Well this discussion about the BWB, seems to be only thoretical. The 787 made a clear statement in Boeing eyes the future in Aviation is with point to point flights, not hub on hub flights. That was the whole point behing the Sonic Cruiser and the 787 Dreamliner.

So building a pane of that size doesn't make sense especially since they are doing very well in terms of sales...

And about a new design, if it wasn't for the hgh oil prices we could have this beauty ready to fly

Interesting thread.

I'm studying Aerospace Engineering in the University of Manchester, UK. At the moment I'm actually writing a report for a new "eco-friendly" aircraft with a potential design etc.

I've read a lot of reports about the aviation industry's impact on the environment and the public perception is pretty exaggerated. For example here's some statistics I found while researching for my project- aviation contributes approximately 3% of all man-made CO2 emissions. Approximately 20-25% of fossil fuels is used in the transportation sector, of this 25% only 12% is used by aviation while 75% is used by road transportation.

Anyways in terms of non-conventional designs being used on future civil aircraft: The blended wing design, while possibly being the most environmentally friendly design (the top mounted engines greatly reduce noise and the large wing and body surface area greatly increase lift; ie. less fuel burnt), it would also be the hardest design to accomodate for and implement. The huge A380 already requires quite a few modifications to airports in order to handle this massive aircraft. Imagine how many changes would have to be made to handle a blended wing aircraft.

Originally posted by Kidder
I've read a lot of reports about the aviation industry's impact on the environment and the public perception is pretty exaggerated. For example here's some statistics I found while researching for my project- aviation contributes approximately 3% of all man-made CO2 emissions. Approximately 20-25% of fossil fuels is used in the transportation sector, of this 25% only 12% is used by aviation while 75% is used by road transportation.

Ah, be sure you are representing that data taking account of the number of passenger miles for each transportation method.


Some papers you might be interested in:

JOURNAL OF AIRCRAFT
Vol. 41, No. 4, July–August 2004
Aircraft Optimization for Minimal Environmental Impact
Nicolas E. Antoine and Ilan M. Kroo


Progress in Aerospace Sciences 40 (2004) 199–235
Propulsion and power for 21st century aviation
Arun K. Sehra, Woodrow Whitlow Jr.


NASA/CR-2002-211754
Ultra Efficient Engine Technology Systems
Integration and Environmental Assessment
David L. Daggett


I have more stuff somewhere, but can't find them - if I do I'll post the links up.

Most of the airplanes look the same. The Boeing 700 looks like the A380. And don't mention the 797 is it the E-170? It looks so small. I want to be a pilot one day. I think the BWB is the best looking concept aircraft. Flying that beauty would be a dream. And what airline would be buying the BWB I now Luthsana would be buying it. They buy almost every single plane. The Sonic cruiser looks a little bit too long at a airport. Also they should make the BWB a little bit smaller. When a 777 or a 747 passes the BWB it might hit each other the wings are too long it should be at least below 200 feet. That was my opion and the rest of the planes are just fine. I am a aviation expert.