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

[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

[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.

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

[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.

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: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:So Lets See,

[fuzzyfuzzyfungus]

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

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.

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.