New 110-160 seat narrowbody -20% fuel design; what do you think

[keesje]

Hi folks I´m new on pprune. Been on other forums but here I hope to get more feed back from more (relatively down to earth) folks upfront :)

Half a year ago I looked at different published studies on new fuel savy and low noise ideas from the US and Europe and asked an internet friend (Henry Lam from Australia) to create an artist impression.

The engines could be e.g. Geared Turbo fans, optimized for low noise and a relative low but fuel efficient cruise speed. The configuartion is further optimized for low noise (tail / wing deflection), low drag (5 abreast cross section) lean wings, and focusses on regional / feedwer / low cost (6 abreast) markets..

http://www.kaktusdigital.com/images/large/LRJ_02_s.jpg
http://www.kaktusdigital.com/images/large/LRJ_02.jpg

Some basic specifications
- Max cruising speed: Mach.7
- Max range with full passenger load: 2200 nm
- Operating Empty Weight: 22,000kg ( 50.000lb)
- 70% Advanced materials CRFP / Alu-Li
- Capasity: 110-165 seats in single class 32 inch pitch

http://gc.kls2.com/cgi-bin/gcmap?RANGE=2200nm%40FRA,2200nm%40DFW,2200nm%40hkg&RANGE-STYLE=shaded&RANGE-COLOR=yellow
2200nm range from DFW, FRA and HKG.

Cabin Comfort
The wide cabin is dimensioned for a comfortable 2-3 + 2-2 lay-out with every seat having two individual armrest. On top of this the aisle is 30inch wide, allowing passengers to pass each other / cabin staff with trolleys. A first are the small roof top windows that spreads a friendly natural light in the cabin, giving every passenger a perception of space. Large windows and luggage bins further enhance passenger comfort.

From an operational perspective, do you think this design is feasible?

[Rainboe]

Attractive design keesje, but I see several shortfalls. Please take this as suggestions, not criticism:

The balance, according to the picture, is incorrect. Large engines, and fairly heavy like that, right at the rear would move the whole wing much further rearwards. That wing position would look right with the engines podded forward of the wing.

The wing appears optimised for long range, high speed flight. This is essentially a shorter-range commuter. What is it to be?

The engine position will lead to critical loading problems. The design must be able to carry full loads. What will be done when the flight is empty or very light? You will need ballast at the front.

I see severe longitudinal stability problems. Tailfins aren't just there to put the airline name on. They are essential and they are large. All I see here are sections of tailplane angled up slightly. Possible severe Dutch Roll problems, total loss of directional control risks, and even though the engines are mounted close to centreline, still severe asymetyric problems in engine failure cases.

Essentially, what has this design got that a re-engined MD82 or B717-200 hasn't got? So can you justify claims of 20% fuel savings? Stick the latest engines into a B717 and you have your efficiencies and save a fortune in development costs over your design.

Embraer also seem to be rapidly soaking up this market very well with the 190, and TU Superjet. It offers nothing new, apart from a fancy tailplane which probably has no real effect on efficiency, and seems to leave question marks over effectiveness.

We're looking at the next step in airliners now with the B787-type systems- the design seems to be pretty well settled on B737 planforms. After that? Something revolutionary is needed- maybe canard designs or 'flying wing' concepts- these are where the exciting design developments are- but they will have to justify themselves! But you must understand why a flying wing will not do for shorter range lower capacity designs.

Whilst your design is new, it is not original, and is only a reworking of present designs. A Caravelle with modern engines and dinky tail? To make it cost effective to develop, a big leap over current designs is needed, like the original Comet/Caravelle layouts were over that period. Something different. All there is is Canard or Flying Wing with 787-type systems.

And remember, whilst the designer may let his imagination run away, the world is very conservative and wants these designs proved before it buys it!

[Bolty McBolt]

Nice Pic
I believe Boeing have a replacement for the 737 on the design board 797??
It may not be a quantam leap like the "Comet/Caravelle" but if the items you list are fuel saving I am sure Mr Boeing will be looking at it indeed
The engines could be e.g. Geared Turbo fans, optimized for low noise and a relative low but fuel efficient cruise speed. The configuartion is further optimized for low noise (tail / wing deflection), low drag (5 abreast cross section) lean wings, and focusses on regional / feeder / low cost (6 abreast) markets..
But I suspect it will be a carbon/plastic aircraft similar to current shapes with a new Gen engines and not very interesting to look at unlike your artists impression pic. :ok:

[llondel]

Rainboe:
Essentially, what has this design got that a re-engined MD82 hasn't got?

I believe work has been done that shows that having the engines above the wing surfaces can reduce the noise footprint on the ground. I don't know if it would be true in this configuration but that's the one thing it would have over any existing commercial airliner.

[Rainboe]

The only designs I can think of like that are VFW614, which failed, and Honda Jet. There are costs to counter the incredibly minute alleged increase in efficiency- much more engine noise in the cabin, a severely restricted view from the window, and possible fire safety considerations. Not convinced it is in any way worth the bother.

I have been mystified since the advent of the 757 why the extremely old 737flight deck shell design has been left a la 55-year old 707/727 layout as opposed to the cool 757 design, which is roomier, more visibility friendly, presumably less draggy, and gives commonality across all Boeing types up to 767. If the NGs all had 757 flight decks and windows, it would have updated the aeroplane even more. Now it's like having a sports car with a post war sit-up-and-beg windscreen!

[Evening Star]

Do as Ilondal suggests and move the engines to over the wing, then follow Rainboe's advice about a proper tailfin, and we have then created the Cheburashka (Antonov 72/74):

http://upload.wikimedia.org/wikipedia/commons/3/36/Antonow_An-72_jno_MACS_97.jpg

[Torquelink]

Allowing for the comments above, the pic resembles easyJet's concept for an environmentally friendly A319 / 737NG replacement "revealed" a few months ago. Presumably, a rear and high engine location would be necessary to allow the installation of sufficiently high bypass ratio fans - or even unducted fans - which wouldn't fit under the wing? Or maybe, on the other hand, go for a high wing.

[Desert Diner]

Well said rainboe.

Those large aft egines will require a honking big tail plus stabilizer to counter the forces (thinking Tu-154).

[Rainboe]

High wings are not nice for airline operations:
*Unattractive landing gear bulges and noisy landing gear operation. Fuselage absorbing landing loads. Less efficient landing gear storage.
*Noisy flap operation in cabin (BAe146 frightening in certain cabin areas)
*Wing de-icing harder to achieve
*Tailplane design problems- T tail needed. Easier to have low tail for engineering and de-icing.
*High wing + high engine= pitch/power problem
*low fuselage- hold access difficulties, although only lower steps needed.
* problem of where to locate airconditioning packs

In your design, I also see elevator design problems. Is this an all moving tailplane? There is not a lot of room on the horizontal section for elevators? Are elevators on the canted sections? It starts getting a very complicated tailplane design. Because of the extreme rearward c of g, a very large moment must be generated at the tail.

I think it would be fascinating trying to predict the next stage in fuselage layout design. The clues are there- I think it will be a retractable canard (lifting vertically to prevent ground damage), blended wing, horizontal double bubble cabin (remember the fuselage has to hold 9 psi- large flat fuselages are out)- find out where you can stick the engines with least nuisance! Please design in a 'Captains rest room/flight deck shower/crew jacuzzi', and give it one of them fancy Airbus pilot tables- we're dead jealous of them! Oh for the luxury of being able to cross your legs inflight!

[chornedsnorkack]

blended wing, horizontal double bubble cabin (remember the fuselage has to hold 9 psi- large flat fuselages are out)-

1) If you increase your bypass ratio and engine diametre, for eample by geared turbofans, you have to decrease cruise TAS. Which you may do. On a 4000 km leg, decreasing cruise TAS from M 0,8...0,85 (850...900 km/h) to M 0,7 (750 km/h) means increasing trip time from 4,4...4,7 hours to 5,3 hours, which you might afford.

ATR 42 and Dash-8 have cruise TAS of 0,5 or 0,55 M. A faster turboprop is possible. Saab 340 is relatively fast, Piaggio Avanti is fast, Tu-114/Tu-95 is fast. Airbus A400 would also be about 0,7 M.

Could someone come up with a mainline narrowbody sized plane with a turboprop or geared turbofan engine, cruising appreciably slower than jets, but appreciably faster than Dash-8 and ATR, and being appreciably more fuel efficient than jets?

If you decrease your TAS and do not simultaneously decrease your wing loading (what for?) you will necessarily fly lower. Therefore, pressurization forces are somewhat smaller, although at 0,7 M probably still large.

What exactly does horizontal double bubble give you, compared to single bubble?

How thick do you think your wing root would be? What exactly do you want to blend?

[Rainboe]

Thinking lifting fuselage with wider cabin and stubbier swept wings- very thick wing root (in fact depth of fuselage)- all the room in the world for fuel, gear, systems, engines, and wider cabin. Think bigger Vulcan, with double or treble joined cylindrical fuselages (with vertical bracing disguised as aspidestra pots), and it's getting towards Boeings latest studies for next gen aeroplanes. Someone will have a picture of the latest model being glide tested (in the UK for some reason).
Found it!: http://www.news.com/2300-11397_3-6207999.html
Don't like engine location, but this has to be the shape for longrange, high capacity aircraft. Really, it's just a Vulcan jazzed up with better engines and a cabin. But to get a cabin that wide and flat, you need cylindrical fuselages side by side in a 'double bubble' or 'treble bubble' (hence the vertical bracing columns), no windows apart from a walkway at the front of the wing, and a very quiet bedroom for the Captain. It is the logical next step.

[Desert Diner]

Might not be bad if the cabin was like someones sitting room.

Might be a bit clausterphobic though if the cabin was full of 32" pitch seats, don't care how many aisles there were. After all there is a reason why planes are still long relatively narrow tubes with lots of windows.

Still, a very nice looking delta.

[chiglet]

Ah,what happens to those engines at high alpha? [I remember watching the Vulcan land]. Reverse thrust...Not until the nose wheel is down. Spoilers? Noise over the paxs' heads, :(
As Mr R said but this has to be the shape for longrange, high capacity aircraft.
I think [without Googling] that Westland Aviation had a "similar" concept in the late 20/early30s, albeit with [obviously] piston engines. And there have been many concepts of the Broad/blended fuselage/wing aircraft. Yet it has not [as yet] been taken up.
watp,iktch

[chornedsnorkack]

What limits small BWB-s is the wing thickness and headroom needed for passenger cabin.
B-2 has the headroom for cockpit, and wingspan and TOW capacity for a longhaul widebody.

Junkers/Mitsubishi G-38 had actually seats in the main wing and forward facing passenger cabin windows, but high drag was a problem. Burnelli had lifting fuselage and much thinner wings, but it was unpressurized.

[Rainboe]

DD- you're getting blinkered by thinking up to now, without projecting ahead. Go for some blue skies thinking! If (when) this thing comes in, we have a group of seats like a movie theatre, with no windows, except forward facing ones with net curtains to draw. They are now producing LCD-type screens 3mm thick. By the time a beastie like this appears, we will have floor to ceiling LCD=type screens, seat compartments screened off by walls showing whatever you like. People would not want a window because of watching whatever can be put on the screens. Look at the job Boeing engineers and cabin designers have done with the 787, and think forward 15 years. You could have side walls completely showing floor to ceiling live views of outside on full height video screens, in HD. Who would want a pokey little window? A camera could be on the flight deck allowing me to demonstrate on a screen 10 feet high my conjuring tricks for 2 hours to 600 people- there is no end to the delights modern technology could bring to a design like this.

So keesj, stop playing about with ancient designs and really let your imagination go! Some of the models in Thunderbird 40 years ago showed more design flair than we see these days. That big green vertical transport aircraft-Thunderbird 2: http://davidszondy.com/future/Thunderbirds/thunderbird2.htm ...... stunning- lifting body, vertical flight, stubby wings- incredible. Talk about ahead of its time!

[llondel]

Some of the models in Thunderbird 40 years ago showed more design flair than we see these days.

I did like Fireflash, apart from the fact that it was a hypersonic aircraft with a very thick wing (1st class is in the wing section) and so would get rather warm trying to push it through the air, even on the edge of space. I assume power was no problem because it was nuclear powered. It was also fun to see the 60s technology used to build it, all the exposed terminals and the High Voltage signs. Modern health and safety would have a fit.

Sadly, the only practical flying machine they had was Thunderbird 6.

[keesje]

Hello folks thanx for the comments ! I already knew the wing is to far forward, it should move to back a few meters.. If possible I will ask Henry if he can find time for an "upgrade".

However the tail design isn't that wild. The reason to do it like this iso a conventional tail is stiffness / weight and more importantly: noise. The tail area deflects a lot of noise above populated areas, probably allowing airlines to fly more to noise restricted airports. Airbus and Boeing have both been experimenting with it for years.. Aircraft like the A10, YF-23 and An225 have similar tail configurations..


http://seattletimes.nwsource.com/ABPub/2006/05/09/2002983476.gif

http://seattletimes.nwsource.com/ABPub/2006/05/05/2002974269.jpg

On lateral stability I think aircraft like the F117 are basicly unstable and still fly. New technology to solve the instability by computer power have been operational for more then 25 yrs & research institutes didn't sit on their hands. All control surfaces and new ones can be used to create the required stability.

I doubt the use of blended wing bodies for passengers for the foreseeable future. Pressurizing a flat body, forces / structure weight / evacuation become a night mare. Maybe for cargo / tanker duties..

The engines on above's design may seem heavier then they are. Sized like CFM's they are high BPR optimized for lower speeds / low fuel consumption. On short flight the minutes aren't that critical, props are popular again, ATR is reengining the ATR's. I think the undected fans won't become popular because of noise. So I "put a (scraffed) casing around it" http://ec.europa.eu/research/transport/news/images/treatment02_6691.jpg

On the wings : I think the balance between earodynamic optimal and operation optimal has moved. Wings are getting longer (787 won't fit many 767 gates). Longer thinner wings is better for almost any distance and the disadvantages of it have IMO become more acceptable with oil prices going north of $80/barrel.

I think the conventional configuration (engine under wing or T tail/engines is not what we are going see see for a next generation of 100-200 seat aircraft.

http://www.aviationweek.com/aw/generic/story.jsp?id=news/aw062507p1.xml&headline=Green%20Debate%20Dominates%20Le%20Bourget&channel=comm

[chornedsnorkack]

The reason to do it like this iso a conventional tail is stiffness / weight and more importantly: noise. The tail area deflects a lot of noise above populated areas, probably allowing airlines to fly more to noise restricted airports. Airbus and Boeing have both been experimenting with it for years.. Aircraft like the A10, YF-23 and An225 have similar tail configurations..


An-225 has H-tail in order not to have fin or rudder blanked by external load. The same reason 747 Shuttle Carrier has extra fins and rudders at the ends of tailplane.

Several other airplanes have H-tails in order to limit the total height - like Electra.

As for noise, I think B-2 has engines over main wing to suppress noise. But your jet blast would interact with the wing lift, like it does on An-72/74.

However, upper surface blowing has another problem. When one engine fails, suddenly you have asymmatric loss of lift in addition to asymmetric loss of thrust.

And if you blow your blast over tailplane? Huge upper surface blowing forces far from your pitch axis! When a tail engine fails, the plane would drop tail due to loss of upper surface blowing...

[Desert Diner]

On lateral stability I think aircraft like the F117 are basicly unstable and still fly.

What is acceptable for the military is not the same as for civilian aviation, especially when carrying passengers.

Try geting someting that is "basicly unstable but still flies" certified to carry passengers. What would happen if you lost an engine?

Going off on a tangent now, I wonder if Concorde would have been certified under current requirements.

[Desert Diner]

Very interesting graphic keesje. But I wonder how far beyond the "drawing board" have these designs progressed.

http://seattletimes.nwsource.com/ABPub/2006/05/09/2002983476.gif

[keesje]

Desert liner, I think Boeing and Airbus (at least the research institues) as shown below seem to move in the direction of aft located engines. Higher BPR's are possible as well as noise shielding, clean wings .

If you look hard enough and knwo the keywords you can even find recent research reports. (source in red)

http://i191.photobucket.com/albums/z160/keesje_pics/progreenconceptdriverairbus.jpg?t=1191533833

Apparently they call the tail "powered tail" and have been doing wind tunnel research, which means it ius probably more then a bad idea..

http://i191.photobucket.com/albums/z160/keesje_pics/poweredtail.jpg?t=1191533953

[llondel]

On lateral stability I think aircraft like the F117 are basicly unstable and still fly.

A lot of military aircraft start with an unstable design and use control electronics to stabilise them for flight. This gives a very fast response to control input, useful if someone's shooting at you or you need to shoot at them. Commercial aircraft tend to be designed for stability so they don't rely on a lot of control software to just keep them in the air. You don't want to be doing barrel-rolls in a passenger plane (707 excepted...) just because your hand twitched.

[Rainboe]

keesj- note the designs have a far greater vertical element than your canted tailplane tips. Rear engines give a rear c of g which requires a far greater fin. I would suggest your first design would have little directional stability. It's all very well for these designs to point out an unobstructed wing is 'more efficient'. It is leaving out the negative side of the design where engines on the wing provide a lot of 'wing bending relief' making the wing structure lighter and simpler. It is interesting that the 'engines on wing' formula (737,757, A320 series) was found to be far more efficient and successful than the rear engined designs (BAC1-11, DC-9 series). Even the Russians have dispensed with rear engine designs and concentrated on 737/A320 planforms with their latest designs. Perhaps a chase after maximum theoretical efficiency is not the most cost efffective way.

I think the next step will be revolutionary, on the lines I suggested. The disadvantages of the traditional tailplane at the back/standard circular fuselage/engines on wing can be overcome. Lifting body, no windows, smaller wings, canard, engines buried within fuselage at rear with noise attenuating B2/F117 type ehausts- then you must have fantastic gains in efficiency and noise. Why would you need windows when the whole sidewall can be large curved LCD screens of the outside view, floor to ceiling? How fantastic would that be? No asking someone to get their head out of the way! The video technology is almost already on us.

[Jet_A_Knight]

Build it in X-Plane using the Plane maker program, and see how it flies.

Many other designers are doing the same, apparently.

[Sl4yer]

Going off on a tangent now, I wonder if Concorde would have been certified under current requirements.

I'm curious about this. Why might it not? Except for electrical signalling, the flight controls are pretty conventional aren't they?

[james ozzie]

Quote:
That big green vertical transport aircraft-Thunderbird 2: http://davidszondy.com/future/Thunde...underbird2.htm ...... stunning- lifting body, vertical flight, stubby wings- incredible. Talk about ahead of its time!
Yes, and powered by a sparkler and a piece of fishing line!

[keesje]

Time to resurrect a 5year old thread,

Embraer now actually is considering an aircraft this size, 5 abreast.

Embraer CEO Frederico Curado during an earnings call today stated in his "humble opinion" a new design by Boeing makes a "lot of sense".
Boeing's ultimate decision will directly influence Embraer's strategy in the 130-seat market, says Curado. "We are waiting to understand where Boeing is going", before taking a decision to engage in the development of a five-abreast aircraft, he explains.

Embraer waits for Boeing?s move before defining new aircraft strategy (http://www.flightglobal.com/articles/2011/03/25/354801/embraer-waits-for-boeings-move-before-defining-new-aircraft.html)

I wouldn't still rule out Embraer and Boeing finding each other either, Embraer < 150 seats, Boeing > 150 seats.. similar to what Bombardier and Comac announced yesterday.

2007 "LRJ" artist impression by Henry Lam, 5 abreast, big geared turbofans.

http://i191.photobucket.com/albums/z160/keesje_pics/LRJ_Boeing_Embraer_Y1_narrow_bod-1.jpg