Fly the Eco-Friendly Skies: Airplanes That Would Use 70 Percent Less Fuel Than Current Models

Science Daily
May 19, 2010

ScienceDaily (May 19, 2010) — In what could set the stage for a fundamental shift in commercial aviation, an MIT-led team has designed a green airplane that is estimated to use 70 percent less fuel than current planes while also reducing noise and emission of nitrogen oxides (NOx).

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The design was one of two that the team, led by faculty from the Department of Aeronautics and Astronautics, presented to NASA last month as part of a $2.1 million research contract to develop environmental and performance concepts that will help guide the agency's aeronautics research over the next 25 years. Known as "N+3" to denote three generations beyond today's commercial transport fleet, the research program is aimed at identifying key technologies, such as advanced airframe configurations and propulsion systems, that will enable greener airplanes to take flight around 2035.

MIT was the only university to lead one of the six U.S. teams that won contracts from NASA in October 2008. Four teams -- led by MIT, Boeing, GE Aviation and Northrop Grumman, respectively -- studied concepts for subsonic (slower than the speed of sound) commercial planes, while teams led by Boeing and Lockheed-Martin studied concepts for supersonic (faster than the speed of sound) commercial aircraft. Led by AeroAstro faculty and students, including principal investigator Ed Greitzer, the H. Nelson Slater Professor of Aeronautics and Astronautics, the MIT team members include Aurora Flight Sciences Corporation and Pratt & Whitney.

Their objective was to develop concepts for, and evaluate the potential of, quieter subsonic commercial planes that would burn 70 percent less fuel and emit 75 percent less NOx than today's commercial planes. NASA also wanted an aircraft that could take off from shorter runways. Designing an airplane that could meet NASA's aggressive criteria while accounting for the changes in air travel in 2035 -- when air traffic is expected to double -- would require "a radical change," according to Greitzer. Although automobiles have undergone extensive design changes over the last half-century, "aircraft silhouettes have basically remained the same over the past 50 years," he said, describing the traditional, easily recognizable "tube-and-wing" structure of an aircraft's wings and fuselage.

Two planes for two missions

The MIT team met NASA's challenge by developing two designs: the 180-passenger D "double bubble" series to replace the Boeing 737 class aircraft, currently used for domestic flights, and the 350 passenger H "hybrid wing body" series to replace the 777 class aircraft now used for international flights.

The engineers conceived of the D series by reconfiguring the tube-and-wing structure. Instead of using a single fuselage cylinder, they used two partial cylinders placed side by side to create a wider structure whose cross-section resembles two soap bubbles joined together. They also moved the engines from the usual wing-mounted locations to the rear of the fuselage. Unlike the engines on most transport aircraft that take in the high-speed, undisturbed air flow, the D-series engines take in slower moving air that is present in the wake of the fuselage. Known as the Boundary Layer Ingestion (BLI), this technique allows the engines to use less fuel for the same amount of thrust, although the design has several practical drawbacks, such as creating more engine stress.

According to Mark Drela, the Terry L. Kohler Professor of Fluid Dynamics and lead designer of the D series, 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. Although the plane would travel slightly slower than a 737, he said that some of this time could be recovered because the plane's wider size should allow for quicker loading and unloading.

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.

Carl Burleson, the director of the Federal Aviation Agency's Office of Environment and Energy, said that in addition to its "really good environmental performance," the D series is impressive because its bubble design is similar enough to the tube-and-wing structure of current planes that it should be easier to integrate into airport infrastructure than more radical designs. "You have to think about how an airport structure can support it," he said. " For some other designs, you could have to fundamentally reshape the gates at airports because the planes are configured so differently."

Although the H series utilizes much of the same technology as the D series, including BLI, a larger design is needed for this plane to carry more passengers over longer distances. 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.

The large structure also allows engineers to explore different propulsion architectures for the plane, such as a distributed system of multiple smaller engines. Although the H series meets NASA's emissions-reduction and runway-length goals, the researchers said they will continue to improve the design to meet more of NASA's objectives.

The MIT team expects to hear from NASA within the next several months about whether it has been selected for the second phase of the program, which will provide additional funds to one or two of the subsonic teams in 2011 to research and develop the technologies identified during the first phase. The researchers acknowledge that some propulsion system technology still needs to be explored. 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.

Canada Bans Pesticides

Huffington Post
May 10, 2010

The smell of lawn chemicals is as dependable a harbinger of spring as robins and lilacs. Not in big parts of Canada, where many municipalities and provinces have opted to abolish the cosmetic use of pesticides on the grounds that the links between pesticide exposure and childhood cancer are too troubling to ignore. So, how come we're still using them?

DDT is now so universally used that in most minds the product takes on the harmless aspect of the familiar.
- Rachel Carson, Silent Spring

Harmless aspect of the familiar was the phrase that leaped into my mind when I watched a scantily clad woman - the day was hot and sunny - lie down in a green sward of grass in front of the Women's Center on the campus of DePauw University in Indiana. Next to her waved a small yellow flag that warned passers-by to keep off the grass as it had just been sprayed with pesticides.

I guess the word irony might also have applied. On the other side of the flag, a card table was piled high with copies of my book, Living Downstream, which, among other topics, discusses the dangers of lawn chemicals. The books were for sale. I was positioned up on the porch, encouraged by my faculty host to chat with students, drink punch, and sign books as part of an informal reception before my all-campus Earth Day lecture.

Yes, I intervened. The reclining woman seemed bewildered by my concern for her, pointing out that the yellow flags are so ubiquitous that no one notices them. She reluctantly promised to shower and launder her clothes before attending the evening's lecture.

No flags wave from the lawns in many parts of Canada. Ontario, Quebec, New Brunswick, and Prince Edward Island - and many cities across the rest of the nation - have expressly outlawed the cosmetic use of pesticides. Within these provinces and municipalities, the use of synthetic pesticides to improve the appearance of lawns and, in some places, gardens is now illegal.

Indeed, Earth Day 2009 - one year ago - was the deadline for hardware and garden stores across Ontario to remove approximately 250 chemical bug and weed killers from their shelves. Beginning on that ceremonial day, as part of a commitment to decrease toxic exposures to chemicals linked to cancer, residents of Ontario could no longer use pesticides on lawns and gardens, and stores could not sell them.

And just how are the organically managed lawns of Canada faring? During my last visit to Toronto, I can't say I noticed any barren, grub-infested yards or playgrounds abandoned to thistles - my grandfather the farmer called them Canada thistles for a reason, right? - and I'm happy to report that all the French-style gardens still looked lovely.

What I did notice is that the legislation outlawing lawn chemicals has become familiar enough to Torontonians to merit an offhand mention in the complimentary magazine in my hotel room. This lushly illustrated guidebook not only trumpeted the city's best restaurants and hottest nightclubs, it also welcomed visitors with the following reassurance:

All green spaces are pesticide-free. In 2004, Toronto became the largest municipality in the world to ban cosmetic use of lawn and garden pesticides. The Sierra Club of Canada reports a clear link between pesticide use and breast cancer; many other studies have shown the dangers to children from chemical exposure to pesticides.

That is precisely the worrisome body of evidence that I review in Living Downstream. When I speak about leukemia and lawn chemicals here in the United States, people in my audiences sometimes tell me that the subject matter is too depressing for them to even contemplate. But in parts of Canada, doing something about it is a selling point for tourism.

The Canadian and U.S. governments have the same scientific evidence available to them - indeed much of the data on children's exposure to pesticides and its possible contribution to pediatric brain tumors were generated on this side of the border. So why have so many jurisdictions in one nation chosen, as a response to that data, abolition of cosmetic pesticides while jurisdictions in the other rely on dinky yellow flags?

In Canada, the ban on nonessential uses of pesticides began with old-fashioned citizen activism in the small village of Hudson in Quebec. (This story is documented in the documentary film A Chemical Reaction.) Upheld by the Supreme Court of Canada, that city's ban was replicated in other communities. Such bans are supported by the Canadian Cancer Society (a counterpart of our American Cancer Society) and by the Ontario College of Family Physicians. Research partially funded by the OCFP concluded, in 2007, that the weight of the evidence indicates a "positive relationship between exposure to pesticides and the development of some cancers, particularly in children ... The authors of the research recommend that exposures to all pesticides be reduced."

Benefit of the doubt goes to children, not to chemicals.

By contrast, federal agencies, mainstream cancer charities, and physicians' organizations south of the border have been more circumspect about the role of involuntary exposures to inherently toxic substances in creating health threats. Why the demurral? Is it because the impulse in the United States is to treat public health threats as issues of personal choice? Thus, lawn flags instead of bylaws?

I don't know the answer here. Let's ask. The mothers of children with leukemia can go first. (A 2009 study found higher levels of household pesticides in urine samples collected from children with leukemia and from their mothers than in the urine of mother-child pairs living in households unaffected by leukemia. Not all of the mothers of these child cancer patients used pesticides themselves. In fact, most did not.)

When it's my turn, I'd like to pose the following query to the American Cancer Society, the National Cancer Institute, and the American Medical Association: I spent a lot of time this spring walking by yellow flags planted in the green lawns of college campuses, on my way to Earth Day lectures. When I pointed the flags out to my student escorts, most of them just shrugged. Meanwhile, to the north, 77 percent of Canadians already benefit from pesticide bans, Environment Minister Sterling Belliveau introduced a bill last week to ban the sale and use of nonessential pesticides for lawn care in Nova Scotia, and momentum grows for a province-wide ban on lawn chemicals in British Columbia. Why can't we do things like this?

Sandra Steingraber is the author of Living Downstream, newly published in second edition by Merloyd Lawrence Books/Da Capo Press to coincide with the release of the documentary film adaptation. The film is having its Canadian Premiere on May 18 at 7:30 pm at the Bloor Cinema in Toronto. This essay is one in a weekly series by Sandra exploring how the environment is within us. www.steingraber.com / www.livingdownstream.com