MIT Designs Aircraft That Uses 70% Less Fuel Than Conventional Planes

greenrainbow writes "Today a team of researchers at MIT unveiled their design for an airplane that uses 70% less fuel than conventional aircraft. The MIT design comes thanks to a NASA-funded initiative to increase fuel efficiency, lower emissions, and allow planes to take off on shorter runways. The team accomplished all of NASA's set goals with their innovative D-series plane, lovingly referred to as the 'double bubble,' which has thinner, longer wings and a smaller tail, and engine placement at the rear of the plane instead of on the wings."

Comments

hmmm

[meerling]

Looks like it's fuselage is also a lifting body.

Re:hmmm

[gyrogeerloose]

Looks like it's fuselage is also a lifting body.

On the larger one, yeah, it does.

Interestingly, TFA mentions that NASA was also soliciting new designs for a supersonic transport aircraft; given the reluctance of nations to allow those in their airspace and the resulting eventual demise of the Concorde (which, IIRC, never made a profit anyway), one has to wonder why.

Re:hmmm

[ircmaxell]

Well, it's possible to travel supersonic with a minimal or even no sonic boom (I remember someone came out with a design for a boom-less Learjet recently). IF they can do that reliably, perhaps the countries will open up their airspace to it... Or perhaps it's a losing battle. Either way, some good science should result from it (What NASA is ultimately, a science organization. It's not Airbus)...

Re:hmmm

[robot256]

Yeah...except it hasn't actually ended yet. Will Obama veto a budget with irrationally-mandated Constellation spending? Only time will tell.

Re:hmmm

[Pence128]

The faster you go, the less time you spend going.

Re:hmmm

[vtcodger]

***The faster you go, the less time you spend going.***

Of course. My understanding is that's why drag related fuel losses only increase with the square of velocity rather than the cube of velocity. Still, given likely future trends in fuel costs, I expect that we're more likely to see zeppelins return than supersonic airliners return.

Re:hmmm

[Grishnakh]

Who cares if there's a sonic boom? A large portion of long-distance air travel happens over the Atlantic and Pacific Oceans. As long as a SST plane slows to subsonic speed before crossing over land, which it'll probably need to do anyway because it's preparing to land, there shouldn't be a problem.

Think about it, most really long flights are going to be trips like LA to Tokyo, LA to Beijing, LA to Sydney, NYC to London, NYC to Paris, etc. The vast majority of the distance is over international waters, and these airports are mostly very close to the water. Obviously, trips over Western Europe will have to be subsonic, but it's really not that far from the Ocean to any airport in Western Europe so the subsonic leg shouldn't be a big deal. Trips over North America can be supersonic, since it's doubtful the American government will care about sonic booms. If they do, I'm sure a few "campaign donations" will fix that....

Even trips from LA to Western Europe shouldn't be a problem, since most of the journey is over the North Pole IIRC.

Re:hmmm

[Grishnakh]

Or a larger slower plane and have a better seat.

Unfortunately, that never seems to be an option. With the way corporations work, you'll have a choice between fast and expensive but cramped like a sardine, or slow and cheap but cramped like a sardine. You'll also need to bring plenty of change to use the restroom.

Re:hmmm

[shermo]

It's my understanding that drag increases as the square of velocity. This leads to fuel consumption per unit of distance increasing linearly.

Go twice as fast, use twice as much fuel getting there. Your rate of fuel consumption is four times higher, but you spend half the time getting there.

Re:hmmm

[cmiller173]

Dallas/Fort Worth - London Heathrow (looks like 50% over land and 50% over water give or take. http://gc.kls2.com/cgi-bin/gc?PATH=DFW-LHR&RANGE=&PATH-COLOR=&PATH-UNITS=mi&PATH-MINIMUM=&SPEED-GROUND=&SPEED-UNITS=kts&RANGE-STYLE=best&RANGE-COLOR=&MAP-STYLE=

Re:hmmm

[Wyatt Earp]

The extra distance would also cost fuel, more fuel, more weight, fewer paying passengers, lower profits and now that route isn't viable, more time in the air, more maintenance and less total life on the airframe.

Re:hmmm

[daBass]

Booms aren't just loud, they also smash Windows and American law-makers care; the FAA specifically bans not sonic booms, but *all* supersonic flight. So even if you came up with a boomless SST, you'd still need the get permissions to go supersonic!

Your views on trips are also rather US-centric. There are a lot of aircraft flying from Europe to Asia, all over land.

If it had not been for this minor boom problem, Concorde would have been a much bigger success.

Re:hmmm

[Wyatt Earp]

Sonic booms are not legal over the majority of the United States and they don't routinely make them over urban areas, I lived in Portland for 14 years and there was never a sonic boom in the area there.

I've heard them, I lived near a high speed route for B-1Bs in the 1980s and they'd break the sound barrier on occasion.

http://www.aerospaceweb.org/question/planes/q0060b.shtml

http://www.kerncog.org/maps/MEAR_atlas/23MilitaryFlightOperationAreas.pdf

http://en.wikipedia.org/wiki/Oklahoma_City_sonic_boom_tests

Re:hmmm

[blueg3]

He didn't say it was a law. (It's not, it's a rule of thumb.)

I'm no aircraft engineer, but for cars, internal frictions are only significant at low speeds. At a respectable speed, all of your power is going to counteracting drag.

Re:hmmm

[Grishnakh]

Booms aren't just loud, they also smash Windows and American law-makers care; the FAA specifically bans not sonic booms, but *all* supersonic flight.

I don't know about the FAA, but I've heard tons of sonic booms from F-16s, and they fly supersonic here all the time. I live in a large metro area near an F-16 training base.

Your views on trips are also rather US-centric. There are a lot of aircraft flying from Europe to Asia, all over land.

Yep, those won't be able to go supersonic. I didn't say all planes could do it, just that there's a lot of long-distance traffic that flies mostly over water.

If it had not been for this minor boom problem, Concorde would have been a much bigger success.

I have a feeling the $5-10k ticket price (in 80s dollars) was also a "minor" problem with the Concorde.

If someone wanted to make a supersonic plane that was economically feasible, they'd make it small, like the size of a Cessna Citation X or some other small corporate jet, or maybe smaller. They'd need to figure out how to get the ticket price down to $10-25k per ticket, with only ~20 passengers or so. There simply aren't enough rich people going the same place, at the same time, to fill up some giant jet with hundreds of seats. However, getting 20 rich people going the same place at the same time who want to get there quickly is a much smaller problem.

Re:hmmm

[daBass]

The larger the aircraft, the bigger the boom. A conventional 200 passenger airliner will create a very big boom.

I was surprised because the Mythbusters couldn't break any windows with an F-18 unless they were at tree-top level. But big booms from big airliners are real.

And it's not just the boom, it's also the engines. Hard to create a supersonic airliner using quiet high-bypass turbofans. Concorde used straight turbojet with after burners: very loud.

Right until the Paris crash, Concorde between London and NYC was full and making a lot of money for BA. (buying the aircraft for peanuts from the government helped) Ticket prices were barely more than 1st class going subsonic.

I would imagine a NYC-LAX service and between other hubs would be equally lucrative; there an aweful lot of very rich folks and companies!

That said: I agree the next SST will more than likely be a business jet.

Re:hmmm

[smellsofbikes]

It's my understanding that drag increases as the square of velocity. This leads to fuel consumption per unit of distance increasing linearly.

Go twice as fast, use twice as much fuel getting there. Your rate of fuel consumption is four times higher, but you spend half the time getting there.

Well... okay, here's the thing. The drag rises as the square of velocity, so the force required to overcome the drag rises as the square of velocity. However, since you're going faster there's another time unit involved, meaning the *power* required rises as the *cube* of velocity. "Thus, the resultant power needed to overcome this drag will vary as the cube of velocity.". And as such your fuel costs aren't rising linearly but exponentially.

Re:hmmm

[Martin Blank]

The FAA has prohibited overland supersonic flight except for explicitly-approved military flights for decades now. Even the military has to get permission when outside of established supersonic corridors, most of which are controlled by the FAA. (Many people are often amazed at how much authority the FAA has over military flights within US borders.)

NASA has conducted a great deal of research into quieting sonic booms, either by deflecting them upward or by canceling them out. I imagine those will be or have been factored into MIT's proposals.

Re:hmmm

[shermo]

Ah, good point.

See my OP for an example of Slashdot: Where you can get +1 interesting for a completely wrong post.

Re:hmmm

[Hadlock]

Well hey, since it's apparently free to fly at supersonic speeds, you could just fly south over Houston, once you hit the gulf just fly around the tip of Florida and up to London!!! It'd be even easier flying from LA - just head south around the tip of Argentina off the coast of south america and it's a straight shot to London!

Re:hmmm

[MechaStreisand]

Not exponentially! No! Something that is rising exponentially is rising as 2^x, which is like hitting a brick wall compared to something rising quadratically, which, if your math is right, is how fuel costs would rise with increasing speed. And your math seems right.

Re:hmmm

[Jarik C-Bol]

Personally, with the deadly safety record of swimming (sharks, jellyfish, cramps, exhaustion) i think I'd rather just stay home and look at pictures of cats on the internet.

Re:hmmm

[westlake]

Trips over North America can be supersonic, since it's doubtful the American government will care about sonic booms. If they do, I'm sure a few "campaign donations" will fix that....

It didn't work for Boeing in the '70s:

The anti-SST paperback, "SST and Sonic Boom Handbook" edited by William Shurcliff, which claimed that a single flight would "leave a 'bang-zone' 50 miles wide by 2,000 miles long" along with a host of problems that would cause. In tests in 1965 with the XB-70 near Oklahoma City, the path had a maximum width of 16 miles, but still resulted in 9,594 complaints of damage to buildings, 4,629 formal damage claims, and 229 claims for a total of $12,845.32, mostly for broken glass and cracked plaster.
Boeing 2707

Think about it, most really long flights are going to be trips like LA to Tokyo, LA to Beijing, LA to Sydney, NYC to London, NYC to Paris, etc.

There are two big problems here.

The North Atlantic run is heavily traveled.

But very competitive and price-sensitive. No matter how quick the turn-around, you need to sell a lot of seats on your SST at super-premium prices to compete against the jumbo jets and charters.

The really long runs over water - and there are not so very many of them, when you come right down to it - don't generate anything like that kind of traffic.

Intrigued to know more

[ICLKennyG]

I wonder how the seating configurations are for these planes. There is no scale provided so you wonder what they are calculating on, is it fuel per mile per passenger? Anything else would be irrelevant.

Re:Intrigued to know more

[AnonymousClown]

Seating is usually dictated by the individual airline that buys the planes. Rest assured that all of the US based carriers will cram as many seats in as possible so even a little guy like me - 5' 7" 155lbs - will feel cramped.

Of course, when the airlines get these, there will be a "green" fee, a "designed by MIT" fee and an "environmental feel good" fee added onto your ticket price along with all the junk fees.

Re:Intrigued to know more

[Chris Burke]

There is no scale provided so you wonder what they are calculating on, is it fuel per mile per passenger? Anything else would be irrelevant.

The two designs carry the exact same number of passengers as the planes they are hypothetically replacing, the 180-passenger 737 and 350-passenger 777, so there's no difference in this case between miles per gallon and passenger-miles per gallon. :)

Re:Intrigued to know more

[blair1q]

Of course, when the airlines get these, there will be a "green" fee, a "designed by MIT" fee and an "environmental feel good" fee added onto your ticket price along with all the junk fees.

And then there's the fee for adding on the fees...

Re:Intrigued to know more

[elysiana]

And then there's the fee for adding on the fees...

Nah, that's already been patented by Ticketmaster.

Re:Intrigued to know more

[CWCheese]

Recalling the BWB work done at McDonell Douglas and Boeing in the '90s, there was considerable resistance from passenger focus groups who could not get comfortable not seeing windows. The arrangement I remember seeing was similar to a theater seating with 3 or 4 rectangular sections in the thickest part of the chord of the wing, which could carry several hundreds of passengers in a ship not nearly as long as a 747. Cost per passenger mile is much better optimized in such an arrangement; perhaps with all the novelty items found in typical Emirates accommodations there will be less resistance to the windowless cabin.

Re:Intrigued to know more

[timeOday]

Recalling the BWB work done at McDonell Douglas and Boeing in the '90s, there was considerable resistance from passenger focus groups who could not get comfortable not seeing windows.

Well, they could always put windows in the floor to make people feel better.

Re:Intrigued to know more

[Type44Q]

Rest assured that all of the US based carriers will cram as many seats in as possible...

Guess you've never been on a Japan Airlines flight!

Slower than current aircraft

[sunderland56]

One way they save fuel: flying slower than current aircraft. First, will customers accept that? And second, why not just fly current 737s a bit slower right now, to save on fuel?

Re:Slower than current aircraft

[sznupi]

While I'm sure you can devise a design which, as part of greater fuel economy, flies slower (turboprops might be just that...) - it won't really work for existing aircraft, like mentioned by you 737s. Airlines take care to fly them at optimal speed, not the greatest speed; optimal for fuel economy.

For example Rynair (which cares greatly about lowering costs...), some time ago, changed the guidalines for cruising speed by...2 or 3 km/h. Accidentally in this case it was lowering it, but might have been just as well an increase; what works best for given airplane / engines / routes / weight combo (didn't stop local journalists from proclaiming "Ryanair will fly slower to save fuel", which was technically correct, but....)

Re:Slower than current aircraft

[h4rr4r]

They sure will. If you can give me a 30% reduction in ticket price but a 10 hour flight instead of an 8 hour one across the atlantic that would be fine by me.

Provided it is a nice European carrier like Lufthansa, who actually has free beer and back of the seat entertainment systems. Unlike American carriers who charge for beer and have 70s entertainment systems in the aircraft.

Re:Slower than current aircraft

[schon]

One way they save fuel: flying slower than current aircraft.

No. While they do fly slightly (10%) slower than existing aircraft, they do that to mitigate engine stress.

will customers accept that?

Well, they seem to "accept" waiting 2-3 hours in security lines, so I'm guesing yes.

why not just fly current 737s a bit slower right now, to save on fuel?

You honestly believe that flying a 737 10% slower will reduce fuel consumption by 50%? I can tell you that if an airline reduce their costs anywhere close to that much, they'd do it in a heartbeat.

Re:Slower than current aircraft

[vlm]

They sure will. If you can give me a 30% reduction in ticket price but a 10 hour flight instead of an 8 hour one across the atlantic that would be fine by me.

Doesn't work exactly like that. Levitating a million pounds of aluminum costs a certain amount per unit time, no matter how slowly you move it. Also the hotel loads of pressurizing, electricity, air conditioning, hydraulics, all are mostly invariant. And cost of inflight food/entertainment increases linearly with flight duration.

The real killer, however, is financial.

To simplify, lets assume the plane instantly loads and departs and magically requires no maintenance nor cleaning. That means the 8 hour flightplan makes 3 trips per day. And the 10 hour flightplan (drumroll as slashdotters get out their HP-48 calculators) makes 2.4 flights per day.

So, your 10 hour flightplan, in addition to lowering revenue by 30%, lowers total DAILY revenue, just due to scheduling by (3-2.4)/3 = 20%. Now you can play games with percentages all day, but be careful adding them or applying one on top of another. Even worse, To continue shipping the same number of bodies around in their current cattle car style, they need 20% more planes. And 20% larger maintenance facilities to process 20% more planes. And 20% more management overhead to supervise the 20% increase in staff. And a 20% higher bond/rent payment to pay for those planes.

And some people simply don't enjoy sitting in a cattle car. So they'll spend a little more dough to avoid it.

I would casually estimate that slowing the planes down with that discount would lower revenues "about" 50% while increasing expenses across the board roughly 25%. Profit margins are low enough that its unlikely any airline could survive that.

If anything, to survive, an airline that slows down "to save the planet!" is going to have to increase ticket costs modestly.

Re:Slower than current aircraft

[LWATCDR]

Actually it is a lot more complex than that.
The higher you fly the less fuel you burn but the higher the stall speed as well as the speed that offers you the best lift to drag.
Also engines have an optimum power setting as well.
Also the higher you fly the more fuel you burn in climb so there is a function of distance, altitude, and airspeed where the plane gets the best efficiency.
The concept D looks like it is using the classic trick of increasing the aspect ratio of the wing. That increases climb rate and improves the lift to drag at a given speed.
My guess by looking at the pictures they are using engines that have a much lower disk loading than current turbofans and a wing that is optimized for cruise at a lowers speed.

The problem will be the increase in weight. When you increase the aspect ratio you increase the weight of the wing. If you decrease the disk loading of a turbo fan the weight goes up. It will be interesting to see if all the lines cross where they think they will.

Re:Slower than current aircraft

[pittance]

You're correct that drag has a large influence, engines have a part to play also.
Turbofans have a 'bucket' speed where their efficiency (specific fuel consumption or the fuel they burn per second per pound of thrust) is best*
The result is that, when the aerodynamics and engine efficiency are combined, there will be a best efficiency speed (best range speed) that's not far below the theoretical 'design' speed. However many airlines fly faster than this, depending on their balance of fixed vs. hourly costs.
Generally you can get higher efficiency by flying slower but you have to make changes to the aircraft, as seen here where much of the efficiency probably comes from the lower lift dependent drag that you can get from the larger spans of these aircraft. They probably get quite a lot of gain from engine improvements also, perhaps half.

*all bets are off with open-rotor or propellor engines, broadly these like to fly slower overall and you lose efficiency steadily the faster you fly.

Re:Slower than current aircraft

[thrich81]

Sorry to differ here, but "using anything over the minimal amount of fuel you need to move will necessarily result in decreased efficiency" -- is not accurate. Aside from the parasitic ("wind resistance") drag which increases non-linearly with airspeed, all aircraft suffer another drag, "induced drag" which is a direct effect of generating lift. Induced drag is greater at low airspeeds and decreases with increasing airspeed. So for any given aircraft weight and configuration there is a compromise ("max range") airspeed which gives the best fuel economy per mile traveled. It is not even true that the airspeed which gives the best endurance (least fuel per minute) is the slowest speed at which the aircraft will stay airborne. Again this is a compromise between parasitic and induced drags. Max range airspeed is pretty fast in jet aircraft -- I'm not an airline pilot but I suspect that they fly near max range airspeed a lot.

Re:Slower than current aircraft

[vlm]

If your flight from new york to LA took an extra half hour and cost 30% less, i don't think anybody would complain

For scheduling reasons, moving the same amount of cattle will now take something like 8% more aircraft. That means that several internal empires will need to expand by at least 8%, in some cases much more. Hourly crew costs and massive management overhead always scales super-linearly. Financing costs for 8% more planes on less revenue will demand a higher interest rate, so financial costs will increase super-linearly.

If an airline did the "slowdown" thing for marketing to "save the planet" they're going to have to increase ticket costs at least 10% merely to break even financially.

Re:Slower than current aircraft

[ubercam]

Fly with Air Canada next time. They offer the same amenities as Lufthansa.

Re:Slower than current aircraft

[BitHive]

Uh, excuse me I'm pretty sure anything American beats the pants off anything European. That's home come it's America, jackass.

Re:Slower than current aircraft

[marcosdumay]

To fly a 737 slower, you'd need to also fly it lower. The net effect is that increases drag instead of reducing it.

How to pressurize it?

[mangu]

A non-cylindrical cabin would be significantly heavier than a cylindrical cabin, if the plane is meant to fly at the same altitude as current planes.

Re:How to pressurize it?

[ThreeGigs]

It's actually two cylindical (or semi-cylindrical) cabins joined together lengthwise, with a stressed interior partition framework. Kinda like a number 8 laying on its side. Pressurization isn't difficult in that case, and the interior stressed partition can be a latticework. It's not a new idea, although it's never been done for reasons of practicality, just a lot simpler to make the body a long tapered tube and be done.

Answered my own question

[Bruiser80]

NASA's link says the 777 design flies 10% slower. A pretty good return!

Wing length is a Really Big Deal

[PPalmgren]

I remember watching a documentary on the new Airbus plane. There are regulations on wing length, and that plane *has* to use the perpendicular tips at the end of its wings to help with lift, or its wings would be too long. If you require longer wings per pound, you will fit less passengers per plane to fit in regulation. They will have to find a way to collapse the wings without adding significant weight or complications to make this practical for larger planes. That is a very big hurdle, maybe they should focus on that next.

I can't remember why, but I remember them stating that the wing length regulations had very good reasons behind them (logistics of current airports being a major one if I recall). I don't think changing the regulations would be practical if that was the case.

Re:Wing length is a Really Big Deal

[pavon]

According to the article the proposed 737 replacement has standard wing length and is suitable for existing airports.

Re:Wing length is a Really Big Deal

[dwye]

> The 70% savings in fuel cost will be sucked up somewhere,

The article mentioned that moving the engines to the rear increased stresses. Replacing engines will use up that savings; replacing airframes even more so. There is a reason that commercial jets have engines in separate nacelles, nowadays, despite the obvious benefits of locating them inside the wing or fusilage.

OTOH, the super-wide bodies might be a real win, unless moving the fuel tanks from the wings decreases crash safety too much.

Re:Wing length is a Really Big Deal

[hey!]

Oh, you can get a heavier aircraft aloft that way, but the wings in a biplane don't give anything like twice the lift. The main reason for the biplane design is not lift, but strength. If you're building a wing out of fabric covered lumber you want to make that sucker stiff so it doesn't bend and snap. That means big, heavy pieces if you have a monoplane. In the biplane the wings, struts and wires form a kind of truss that is lighter for the same stiffness.

Can it fit into most airport's taxiways and gates?

[gront]

Sure, long thin wings, or a flying wing design are great, but widening aircraft past existing designs would be a nightmare for airports. There is a certain amount of space to fit airplanes while they are moving around on the ground, and wider planes = more of a hassle.

http://blog.flightstory.net/272/airbus-a380-hits-hangar-in-bangkok/

http://home.iwichita.com/rh1/hold/av/avhist/abs/a380flys.htm

Re:So Lets See,

[MBGMorden]

Having a viable prototype design that's gone through simulations and the like is a lot more than artists renderings. What the hell do you think they do to make an airplane? Take some steel, rivets, and aluminum out to the hangar and just see where things end up?

Re:So Lets See,

[fuzzyfuzzyfungus]

Well, that and a bottle of jack daniel's, yeah...

Re:Great... now its up to the aerospace companies.

[sznupi]

You're forgetting about Embraer or Bombardier. Companies which start to introduce ever bigger planes, ever closer to competing directly with Boeing/Airbus/Tupolev mainstray (B737, A320). And also using "classical" design...

Both of TFA's linked sadly lacking in details

[Larson2042]

I'm disappointed in both of the linked articles. Some real substance about the design would have been nice, but as it is, I'm left with a lot of questions:
-70% less fuel? How much of that is aerodynamic savings and how much of that is engine efficiency savings?
-Did they do any wind tunnel testing of their model? How close were their CFD and tunnel test results?
-Are they using engines based closely off existing ones, or are they projecting fuel savings 25 years into the future (the 2035 time frame from the article)?
-What sort of structural weight-saving advances are they assuming, or projecting from?
-So they made the tail smaller, what makes up for the reduction in control authority there?
-Plus other more detailed questions based on the answers to those questions. Would it have been so hard for MIT to link a design document pdf or something? I guess not being a public university, they don't have to if they don't want to. Too bad.

Re:Both of TFA's linked sadly lacking in details

[denzacar]

-70% less fuel? How much of that is aerodynamic savings and how much of that is engine efficiency savings?
5% here, 5% there...

the design mitigates some of the drawbacks of the BLI technique by traveling about 10 percent slower than a 737. To further reduce the drag and amount of fuel that the plane burns, the D series features longer, skinnier wings and a smaller tail. Independently, each tweak might not amount to much, but the "little 5-percent changes add up to one big change," Drela said.

-Did they do any wind tunnel testing of their model? How close were their CFD and tunnel test results?
No actual model. Just the ones in the computer.

They have proposed evaluating the interactions between the propulsion system and the new aircraft using a large-scale NASA wind tunnel. Even if the MIT designs are not chosen for the second phase, the researchers hope to continue to develop them, including testing smaller models at MIT's Wright Brothers' Wind Tunnel and collaborating with manufacturers to explore how to make the concepts a reality.

-Are they using engines based closely off existing ones, or are they projecting fuel savings 25 years into the future (the 2035 time frame from the article)?
Mostly projection and wishful thinking. Right now, they could MAYBE do 50%.

Not only does the D series meet NASA's long-term fuel burn, emissions reduction and runway length objectives, but it could also offer large benefits in the near future because the MIT team designed two versions: a higher technology version with 70 percent fuel-burn reduction, and a version that could be built with conventional aluminum and current jet technology that would burn 50 percent less fuel and might be more attractive as a lower risk, near-term alternative.
.
The researchers acknowledge that some propulsion system technology still needs to be explored.

-What sort of structural weight-saving advances are they assuming, or projecting from?
Only mention of weight-saving is regarding the H-series that should replace 777s.

The MIT team designed a triangular-shaped hybrid wing body aircraft that blends a wider fuselage with the wings for improved aerodyamics. The large center body creates a forward lift that eliminates the need for a tail to balance the aircraft.

-So they made the tail smaller, what makes up for the reduction in control authority there?

The researchers acknowledge that some propulsion system technology still needs to be explored.

-Plus other more detailed questions based on the answers to those questions.

The researchers acknowledge that some propulsion system technology still needs to be explored.

Re:Questions

[blair1q]

By 2035 it's almost certain those will be carbon-fiber aircraft.

The fuel will be somewhere in the fuselage, possibly in the seat cushions (oh don't roll your eyes like that would make flying any more dangerous).

Moving the moment of inertia in will make the aircraft less stable about its forward axis, but computer flight algorithms will keep it from wobbling too much.

Re:So Lets See,

[Chris Burke]

I would like to give you the benefit of the doubt as a result of the flattering implication that engineering involves artistry, but on the whole you've got such an ignorant and insulting view of aerospace engineering that I can't call it anything but ignorant and insulting.

Burt Rutan drew up some "artists' renderings" (they're called CAD models usually) of a plane that in computer models appeared to be able to circumnavigate the world without refueling. Then they built it and it did.

Aerospace firms around the globe rely on computer models to predict the aerodynamic behavior of everything from commercial airliners to supersonic fighters. They use these models because they work. They may not be perfect, but they can be used to reliably predict the behavior of designs in the real world within a margin of error.

The idea that just having the computer model means there's "nothing to see here" is simply wrong. Anyone with a clue would be impressed that they could demonstrate these fuel savings even though they are just in a simulation.

Re:So Lets See,

[EdZ]

It's not impossible. I used to bullseye flow dynamic calculations on my Ti-15 back home, they're not much bigger than two OOM.

Type D ment to work with existing airports

[buback]

The type D is specifically designed to work with existing airports without drastically changing the terminals.

The type H, however, would require changes to current airports. The article says that these designs are planed for a 2035 deployment, though, so plenty of time to make the requisite changes, if the airlines so chose.

Re:Great... insurance

[dltaylor]

It took FOREVER to get a composite commercial aircraft into production because the insurance companies had no data on hull integrity to do the underwriting. As a result, the proposed premiums were based on utter disaster.

It may have been the Beech Starship http://www.wingsoverkansas.com/legacy/article.asp?id=775 that provided some useful data. Although a turboprop, it is pressurized, and the more-frequent pressure cycling of a corporate hauler may have given them some idea that composites aren't highly more likely than conventional aluminum hulls to become convertibles (Aloha 737) in flight.

If the US gov't really wanted to help advance the aircraft industry, they'd create an insurance agency for new designs and materials.

I wonder which engines they used ...

[Aviation Pete]

So far, two thirds of efficiency improvement has been gained by the engine makers, not the airframe designers. If those planes are intended for 2035, I suspect that the guys at MIT extrapolated the current engine efficiency a quarter of a century into the future and had already half of the savings pocketed, without having to improve the airframe a bit. Attaching glider-like winks did the rest, easily.

Icing

[arikol]

Interesting designs. Looking at the first one I have some reservation to this. Structural integrity of the wings is one. A wing has to effect a mass-flow large enough to lift the aircraft, and so has to be fantastically strong, as well as large enough to cause this massflow. A problem (or rather a limitation) with gliders is that when the aspect ratio gets very high that means that there is precious little internal volume to the wing for load bearing members. This is a very real limitation on sailplane wings and means that 20 metre wingspan is a real world limit (some types have gone longer, but the extreme flex of that length of wing means that they are impractical). This seems like a very real issue here.
Of course, high aspect ratio wings are more efficient due to a number of effects, an important one being wingtip vortices affecting a smaller percentage of the wing. I have no idea how that pans out at high speeds, though. When you're reaching M0.8 I would imagine that interesting effects might start happening, but I'm sure that the MIT kids have calculated all that as well as can be done (I doubt them being dumb).

Icing would also be a concern, both for the wing (high aspect ratio, laminar flow) and (more seriously) for the whole fuselage which pollutes the airflow into the engines. MD80's (and other jets with rear fuselage mounted engines, the CL60 is another example) had some accidents due to ill visible icing forming on the wings prior to take-off, detaching from the wing on take-off and flying into the engines. This design would be quite sensitive to this sort of problem.

But all in all, a very intriguing design idea. Would be interesting to see if the real world problems can be solved as well.

Re:Icing

[Falconhell]

(some types have gone longer, but the extreme flex of that length of wing means that they are impractical)

I am quite sure my friend who owns an ASH 25 (26M span) http://en.wikipedia.o/wiki/Schleicher_ASH_25 would disagree, he flys it nearly every weekend.

  I have flown 25 hours in it myself and whilst it is slow in roll the flexibibity of the long high aspect ratio wing makes for a vey comfortable ride. (Think of the wing as a leaf spring, supporting the fuselage)

The largest production glider is the ETA

http://en.wikipedia.org/wiki/Eta_Aircraft_eta

I do however agree that 20M gliders are easier to handle in the air, I prefer the Duo Discus and the
DG 1000 to flying the ASH.

Hmmm... slower than a 737

[DieByWire]

the design mitigates some of the drawbacks of the BLI technique by traveling about 10 percent slower than a 737.

I wonder if they accounted for the added weight of beefing up the trailing edge of the wing to withstand bird strikes.

You lost me at 2035

[tyrione]

Get this down to 2020 and I'd be impressed.

And that's why math education is so important

[A nonymous Coward]

The fees for adding on the fees for adding on the fees need calculus to calculate correctly, and since there are so many variations on the fees, a canned list won't so. Thus we need to make sure that all ticket agents know calculus!!!!!

Re:How Fast?

[Falconhell]

The ratio of length to chord of a wing is refered to as aspect ratio.

To simplify somewhat, the tip of a wing is always
producing a vortex, which reduces the lift contribution of that part of the wing, and increases drag. Winglets are desigend to help reduce this loss.

So the longer the wing the less percentage of it is tip, and the efficency increases.

Hence gliders having high aspect ratio wings.

At low speeds this is good, but at mach speeds a low aspect ratio delta wing gets better results.

It is difficult to make a thin high aspect ratio wing strong due to engineering constraints.(The thinner the wing the more strength required in the main spar which carries the bending loads)

Re:My plane uses 100% less fuel.

[Falconhell]

As a working figure, 330M per 10KM is an glide ratio (L/D) of 30. Are you claiming an L/D of 600+?

Re:Not quite...

[VisceralLogic]

We really need a new term for all these "we have a pretty picture and some untested numbers we came up with" articles. Vaporware doesn't really cut it anymore. Something like renderware, or CGIware, or imagineware...

The term you're looking for is "conceptual design."

Boom?

[Lost Penguin]

Where's the kaboom? There was supposed to be an earth-shattering kaboom!

Certification

[konohitowa]

Prototypes are fun and all, but let's see the numbers once it has customers lined up and has gone through FAA certification. That's a bit like coming up with a car that gets 175MPG (of actual gasoline or diesel, not "gallons" of electricity) -- until you've gotten it past the EPA and the DOT and can still sell the thing to more than the wealthy toy market, it's just a show car.

Believe it or not, they actually have one or two smart people working at Boeing & Airbus (possibly one at each) and it's not like they're in bed with BIG OIL!!!! or whatever other tinfoil hatted fantasy people like to believe in this week.

And, in regard to some other post here, I seem to recall winglets being there to break up parasitic drag from vortices spewing off of the wing tips. But that's just my recollection from working on MD-11 (software, not mechanical design, so take that for what it's worth). They're fairly common now.

strong whiff of 'Jetsons' fantasy horseshit here.

[Simonetta]

...while accounting for the changes in air travel in 2035 -- when air traffic is expected to double -- would require "a radical change,"

    These guys are in a clusterfuck headspace. They are basically throwing fantasies off each other.

    Given the present state of known oil reserves (and the difficulties in accessing those reserves), the current depletion rate, and the expanding rate of oil usage in the developing world, NO ONE seriously expects air traffic to double by 2035. No one except a handful of tech nerds in NASA and the Defense Department think-tanks who get paid big bucks to let their imaginations run wild without any consideration of the conditions in the real world.

    The airlines will be lucky to exist at all by 2035. In all likelyhood, there will be one airline in the world that offers once daily flights across the major oceans at enormous cost for the public, and small-jet charter service for the ultra-rich. The hoards of lower-middle-class masses (that you and me and rest of the Slashdaughters reading this) are not going to jetting to Vegas or Hawaii for wild-weekends as they did during the millenium years 1985-2010. Every six months we read in the business sections about another national airline merging with a major carrier and the major carriers merging with each other. What was it last month? Oh yeah, United and Continental merging because they are both going broke as individual companies.

    I also fail to see how a plane design that looks more or less exactly like all the other plane designs is going to be able to fly 100+ passengers with 70% less fuel. Maybe I missed the football-field-sized helium balloon that was attached to the fuselage (and cropped from the picture). Oh yeah, the front nose looks beveled. And this is supposed to give it 'super lift'. If this were the case, don't you think that Boeing and/or Tupolev would have figured that out twenty years ago?

    Again, these guys get paid to fantasize. Not produce reality. They're the same type of guys who promised us Howard Johnson's restaurants on space stations and PanAm weekly service to luxury hotels on the moon in the film 2001:A Space Odyssey forty years ago. And what was 2001 in reality? Millions of screaming kids and dorks in shorts riding a trashy 30-year old 737 to Branson and Disneyland.

    Trust your instincts. Don't trust MIT/NASA reports.

Pushing tin

[ArundelCastle]

and engine placement at the rear of the plane instead of on the wings.

Rear wheel drive? Nuh-uh. Bigger chance of hydroplaning. ;)

Or as they like to say on WestJet... "should this flight become a cruise..."

Move along...

[Evtim]

You know, people, it is perhaps shameful to admit in front of this audience but despite working at the cutting edge of technology I only shrug at news like this one. Instead of all the exiting engineering/scientific thoughts that most of you exhibited and made the discussion interesting the only thing that crossed my mind was something like:

"So, we are going to save 70% of the fuel. What would happen in such "vacuum" Well, we will just build 70% more plains, fly even more people around, cheaper perhaps so the "gain" in efficiency will be quickly drowned by the increased volume of planes and passengers. Move along, nothing to see here..."

I don't want to rain on anybody's parade but every time when some new technological development frees us time, it is immediately filled with more work, not more recreation or hobbies or family life. When it comes to food and water it is even worst. Just consider the "green revolution" from the 70's. Population pressure due to the baby boom after the war. Solution - industrial agriculture which completely kills the taste of food (especially fruits and vegetables) but its efficient and easier to transport and preserve. When it was all over , did we wipe out the noble sweat and sat down to enjoy the fruits of our ingenuity (pun intended)?

No, because the population pressure was already pushing us again. We will never catch up with this. And as every scientist will tell you , every next step will require more energy and more effort to squeeze maximum yield from minimum volume. Asymptotic approach to use the proper term. Like trying to accelerate a mass to the speed of light. As long as we do not stop the geometrical progression of our multiplication we will never be able (most of us) to enjoy what the progress is all about - giving MORE time for ourselves and our personal development and personal life. Giving MORE and higher quality goods and services per person (population flat, but efficiency increases).

Globally as humans we experience what we people in the west experience with the constant inflation - you have to run ever harder just to stand still. Miss one year's promotion or a raise and your buying power goes down. The effect of missing one year only is accumulative like compound interest. I am sick to the teeth that I have to run like a mouse on an endless tread just to stand still. Just to exists. And being told all the time how good I have it.