Guest Post by Sarah Jensen from the Ask an Engineer series, published by MIT’s School of Engineering

Because 15th-century sailors didn’t have GPS…

Photo: Jo Schmaltz

Photo: Jo Schmaltz

Adventure novels and history books are filled with harrowing stories of sailing ships delayed at sea—tales of sailors running low on food and fresh water, dying of scurvy, and getting trapped in the doldrums, or the tropics during storm season. Unless sailors knew how fast they were going, they could end up days off schedule, endangering those on board and worrying loved ones awaiting them in port.

“With no landmarks to gauge their progress across the open sea, sailors couldn’t tell how fast or how far they were traveling,” explains Camila Caballero ’13, former academic coordinator for Amphibious Achievement, an athletic and academic outreach program for urban youth in Boston. But when the nautical mile – 1.852 kilometers – was introduced in the 15th century, they had a handy standard against which to measure speed and created out of necessity the chip log, the world’s first maritime speedometer. “They used materials they had on hand,” she explains. “A wedge-shaped piece of wood, a small glass timer, and a really long rope.”

But not just any rope would do. Based on the length of the nautical mile, knots were tied along the log line at intervals of 14.4 meters. One end was secured to the ship’s stern and the other was attached to the wooden board, which was dropped into the water. “As one sailor watched the sand empty through the 30-second glass, his shipmate held the line as it played out behind the ship and counted the knots as they passed between his fingers,” says Caballero. Dividing that 14.4 meters by 30 seconds told them that one knot equaled 1.85166 kilometers per hour, or one nautical mile. By performing the calculation using the actual number of knots that unspooled, the sailors were able to measure the ship’s speed.

The average of frequent measurements taken throughout the day proved to be a highly accurate reflection of how fast a ship was moving. The data was used to help them navigate by dead reckoning, the method used before the advent of modern instruments.

Today, maritime speed is determined by ultrasonic sensors or Doppler measurement, and the 30-second divisor in the rate equation has been replaced by 28. But the instrument for measuring a vessel’s speed is still called a log, and marine and aeronautical distances are still measured in nautical miles. “Maps used at sea and in the air are based on the earth’s circumference,” says Caballero. “Their scale varies with latitude, and the nautical mile, about 500 feet longer than the land mile, reconciles those differences.”

And in both today’s pilothouse and cockpit, the speed equal to one nautical mile an hour is still called a knot, the term an echo of the days when crewmembers of square-riggers and caravels got creative with a few simple materials and produced an essential and significant little gadget.

Thanks to S. Venkatesh from Tirunelveli, India, for this question. Visit the MIT School of Engineering’s Ask an Engineer site for answers to more of your questions.

More information about Amphibious Achievement and their third annual Erg-a-Thon

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Update: Happy April Fools’ Day! Currently, there are no plans for a moving walkway in the Infinite Corridor. Walk safely! 

The Infinite Corridor may soon seem much less infinite. Beginning in 2015, portions of the corridor will include a moving walkway, called Zero Footprint, which will allow members of the MIT community to safely text, read a book, or study as they travel through the corridor.

The proposed walkway—similar to the slow-moving conveyors commonly seen in airports—was designed by researchers at MIT’s Historical Edifice Innovation Center and will have a dual purpose of safety and sustainability. According to a new MIT study, 30 percent of MIT students reported injuries related to texting or reading while walking within the Infinite Corridor or other busy MIT pathways in the past school year.

Fran Swanson, Hayden S. Finch Professor of Building Theory, says the walkway will add another layer of safety to campus while also being mindful of MIT’s commitment to sustainability. Zero Footprint will be a first-of-its-kind carbon-neutral moving walkway.

A mockup of Zero Footprint. Credit: Alan Scott

A mockup of Zero Footprint. Credit: Alan Scott

“It’s called Zero Footprint because it will create nearly 95 percent of the power required to operate,” explains Swanson. “The most important issue is student safety, but the name is a nice tie-in with the Infinite Corridor. It explains just how sustainable this new installation is.”

Based on research from MIT’s Urban Re:Construction Lab, Zero Footprint will be powered almost entirely by piezoelectric tiles that will frame the walkway. Those who choose to walk outside of Zero Footprint will generate energy with each step on the tiles.

To allow for maximum mobility within the corridor and easy on/off access, Zero Footprint will consist of five short moving walkways.

Additionally, to mitigate traffic congestion in the corridor, Zero Footprint has been designed as a one way walkway that will change direction depending on traffic flow. For example, as students rush to campus for morning classes, Zero Footprint will move away from Lobby 7 towards Bldg. 4. The walkway will then reverse directions in the late afternoon as students return home.

Plans for Zero Footprint are pending final review by the Cambridge Historical Commission. Currently, construction on the walkway is slated to begin April 1, 2015.


Guest Post by Peter Dunn from the Ask an Engineer series, published by MIT’s School of Engineering

In an era when everything else is accelerating, airplanes are actually flying at slower speeds than they used to…

A 1950s advertisement for the Boeing 707; Credit: 1950s unlimited

“Your link to faraway continents in hours less time: the new, fabulously swift Boeing 707.”
Credit: 1950s unlimited

Specified cruising speeds for commercial airliners today range between about 480 and 510 knots, compared to 525 knots for the Boeing 707, a mainstay of 1960s jet travel. Why? “The main issue is fuel economy,” says Aeronautics and Astronautics professor Mark Drela. “Going faster eats more fuel per passenger-mile. This is especially true with the newer ‘high-bypass’ jet engines with their large-diameter front fans.”

Observant fliers can easily spot these engines, with air intakes nearly 10 feet across, especially on newer long-range two-engine jetliners. Older engines had intakes that were less than half as wide and moved less air at higher speeds; high-bypass engines achieve the same thrust with more air at lower speed by routing most of the air (up to 93 percent in the newest designs) around the engine’s turbine instead of through it. “Their efficiency peaks are at lower speeds, which causes airplane builders to favor a somewhat slower aircraft,” says Drela. “A slower airplane can also have less wing sweep, which makes it smaller, lighter and hence less expensive.” The 707’s wing sweep was 35 degrees, while the current 777’s is 31.6 degrees.

There was, of course, one big exception: the Concorde flew primarily trans-Atlantic passenger routes at just over twice the speed of sound from 1976 until 2003. Product of a treaty between the British and French governments, the Concorde served a small high-end market and was severely constrained in where it could fly. An aircraft surpassing the speed of sound generates a shock wave that produces a loud booming sound as it passes overhead; fine, perhaps, over the Atlantic Ocean, but many countries banned supersonic flights over their land. The sonic-boom problem “was pretty much a show-stopper for supersonic transports,” says Drela.

Some hope for future supersonic travel remains, at least for those able to afford private aircraft. Several companies are currently developing supersonic business jets. Their smaller size and creative new “boom-shaping” designs could reduce or eliminate the noise, and Drela notes that supersonic flight’s higher fuel burn per passenger-mile will be less of an issue for private operators than airlines. “But whether they are politically feasible is another question,” he notes.

For now, it seems, travelers will have to appreciate the virtues of high-bypass engines, and perhaps bring along a good book.

Visit the MIT School of Engineering’s Ask an Engineer site for answers to more of your questions.


The winter issue of MIT’s Spectrvm showcases MIT research on making cities more livable, efficient, and sustainable. Certainly, they are growing—by 2050, two-thirds of the world’s population is expected to live in cities. The work of many of MIT’s architects and urban planners, who are working on the problems and opportunities inherent in this rapid growth, is covered in this issue.

Fab Lab champion Neil Gershenfeld chats with students at Boston’s South End Technology Center. Photo: Len Rubenstein

Fab Lab champion Neil Gershenfeld chats with students at Boston’s South End Technology Center. Photos: Len Rubenstein

A trend toward sharing assets, rather than owning them, offers opportunities to live more conveniently and less expensively. Professor J. Meejin Yoon has proposed the Shareway, a transformation of the I-95 Boston-Washington route into a multi-layer transportation artery that would include a high-speed rail system along with cars, bikes, and pedestrians. Kent Larson, director of the City Science Initiative in the MIT Media Lab, says his group is designing 300-square feet apartments that can function at twice their size. A 10-year study launched by the new Center for Advanced Urbanism will examine how physical design can improve human health, even as urban density seems destined to increase. Read the full article, “The Future Is Cities,” for more. Other highlights:

Do-it-Yourself Manufacturing

Fab labs, workshops equipped with computer-controlled tools for making things, have spread across America and beyond, championed by MIT and offering city dwellers a place to build furniture or a startup prototype. This form of do-it-yourself manufacturing, pioneered by Professor Neil Gershenfeld, is helping cities evolve by sparking local, small manufacturing businesses and teaching young people to be self-sufficient.

Noelle Eckley Selin works to cut air pollution in urban areas.

Noelle Eckley Selin works to cut air pollution in urban areas.

Pollutants to Smart Policy

Noelle Eckley Selin’s research tracks air pollution and determines its economic impact. When she found that air pollution in China cost the country $112 billion in 2005, environmental policymakers worldwide took note. Recently the assistant professor has turned her computer models on the effects of potential climate policies on air pollutants and human health across the northeastern U.S.

Read Spectrvm online and check out Continuum, Spectrvm’s blog. In a recent post, learn about Alexandra Witze ’92, a correspondent for Nature, who parlayed her earth science studies into a career as a science writer.

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Virgin Galactic, the Mojave, California-based firm that aims to bring the world’s first commercial passengers to space, named Steven Isakowitz ’83, SM ’84 as its first president this week.

Isakowitz assumes the leadership role in a dubious time for non-commercial space travel. NASA, where Isakowitz recently served as deputy associate administrator, has seen its appropriations cut this year to nearly the lowest in a decade.

Steven Isakowitz ’83, SM ’84. Photo courtesy Virgin Galactic.

Steven Isakowitz ’83, SM ’84 poses with SpaceShipTwo. Photo courtesy Virgin Galactic.

At the same time, Virgin Galactic’s proverbial star has risen. Founded by Richard Branson in 2004, the firm announced its 600th passenger booking for its commercial program last month. Its inaugural flight may take off as early as December.

Rumored to be among those 600 passengers, who each booked a $250,000 seat on Virgin Galactic’s SpaceShipTwo: actors Brad Pitt and Angelina Jolie and pop singers Justin Bieber and Katy Perry.

“This is a transformational company and I am honored to take on this new role,” said Isakowitz. “As we chart an exciting course into the future of commercial space travel, I could not imagine a better team with which to do it.”

Isakowitz’s challenges as president will be formidable ones: leading the company through this critical first flight, negotiating rights to use the nation’s first spaceport, supporting NASA’s continuing mission, and growing its own researchers’ talents. Another challenge will be bringing that space-flight price tag down, one that certainly makes a summer vacation to Europe by contrast more appealing.

And of course, there’s safety.

“Our goal is to be the safest spaceflight vehicle in history,” Isakowitz said in a recent interview with Forbes, “but this does not equate to risk free because the safest ship is one that never leaves the harbour. We selected a vehicle that was safe by design and that has a very small number of critical systems, which supports safety through simplicity. Our system allows for a safe return for all involved even if there is an issue with the mission.”

Isakowitz joined Virgin Galactic in 2011 as its EVP and CFO. Before his work in space travel, Isakowitz served as CFO at the U.S. Department of Energy under Presidents George W. Bush and Barack Obama and as a branch chief for the White House Office of Management and Budget. He began his career as an aerospace engineer and project manager at Lockheed Martin.


Claude von Roesgen ’79 needed a way to combine his love of Lake Winnipesaukee with his zeal for alternative energy and simple living. A lake cabin was too much work, and an RV lacked charm and guzzled gas.

Tiny house, solar boat before launch. Photo: Roger Amsden.

Readying for the launch. Photo: Roger Amsden.

This year, von Roesgen struck on the perfect solution: a tiny house. On a pontoon boat.

After constructing both house and boat this spring, von Roesgen held a christening and launch ceremony last week in Meadowbrook, NH.

The tiny house movement appealed to von Roesgen from the minute he learned of it. These “were structures that were built on trailers to avoid having to meet building codes that would otherwise force one to build a much larger house,” he says. “The fact they were on a trailer made them movable of course.”

To help him construct the house, von Roesgen recruited his neighbor, Bob Wallhagen SM ’66, who owns a construction company in Carlisle, MA. Once it was complete, Wallhagen maneuvered the house carefully onto the 28×14-ft. pontoon craft and anchored it into place using a giant forklift.

To power the house and the boat, the two alums installed solar panels capable of producing 2.4 kilowatts and storing it in a lithium-ion battery for up to five days. Von Roesgen will power a microwave oven, refrigerator, and a 4000-watt electric motor on the boat from the stored energy.

Though the motor might not produce waterski-capable speeds, Von Roesgen will use it for what he loves best: traversing New England waters. “I’ve always been interested in energy conservation as I grew up during the oil shocks of the seventies,” he says. “And compared to my pedal kayak, going 2-5 mph without effort will seem luxurious.”

From left, Claude von Roesgen '79, Carla Schwartz, and Bob Wallhagen SM '66 on board the houseboat. Photo: Roger Amsden.

From left, Claude von Roesgen ’79, Carla Schwartz, and Bob Wallhagen SM ’66 on board the houseboat. Photo: Roger Amsden.

Von Roesgen aims to live in the tiny-house-boat this summer and do the same on other northeastern lakes for many summers to come, moving it between waterways on a trailer. “I may try Moosehead Lake, Lake Champlain, Erie Canal, Lake George, Lake Saratoga,” he says.

Tiny houses have long been a favorite design challenge within the MIT community, from the MAS.863 course “How to Make (Almost) Anything” to the Center for Bits and Atoms’ Fab Lab house.


Most riders on the MBTA (the public train system known locally as “the T”) have one simple goal: the shortest trip possible. No delays, no missed trains, and no mysterious underground breakdowns. The quickest trip is always the most enjoyable.

MBTA_Tweet_2A group of graduate students in the MIT Transit Lab had a different motive: visit every stop on the T’s Red, Blue, Green, and Orange lines in a single day. Transit Lab student Raphael Dumas documented their experiment in real time, live-tweeting throughout the adventure using the hashtag #TDay.

The students accomplished their goal on June 22. Beginning at the Red Line’s Park Street station shortly after 9 a.m., the group traveled each of the T’s major lines—with a few bus transfers for variety—in slightly over 12 hours.

MBTA_Tweet_1Dumas told Boston Magazine that their purpose was two-fold: a fun adventure that directly ties in with the group’s coursework. The Transit Lab’s research focuses on transit policy, operations planning, and transportation modeling.

From Boston Magazine:

“None of us had ridden the whole network, so we decided to challenge ourselves to see if we could do it all in one day,” he said, adding that some schoolwork was involved. “I’m working on an algorithm in the MIT Lab to look at where people get in and out of the network.”

MBTA_Tweet_4A few observations from their journey, via the #TDay twitter stream.

  • The Red Line has the most parking lots, but also the most public bathrooms.
  • The Blue Line is the cleanest.
  • The Green Line’s D Branch is the most scenic.
  • The Redline’s Mattapan high speed rail line, which passes through a cemetery, is the prettiest.

Their travels also included a stop in Harvard Square, a stroll on the Blue Line’s Revere Beach, a detour to find Dumas St. off of the Red Line, and a brief period of self-doubt.

The final stop, the Green Line’s Boston College station, occurred shortly before 10 p.m. In addition to Dumas, the Transit Lab travelers included William Chow, Katie Pincus, and Michael Gordon.

MBTA_Tweet_3The MIT Transit Lab research team includes research associate John Attanucci SM ’74; Haris N. Koutsopolous SM ’83, PhD ’86; Frederic Salvucci ’61, SM ’62; and Nigel Wilson SM ’67, PhD ’70.

The team has participated in the development, design, and construction of San Juan’s Tren Urbano rail system, Chicago’s Circle Line and Airport Express projects, and Boston’s MBTA Silver Line.

Screenshots via @DumasRaphael.


Photo: Chelsea He SM '10

Photo: Chelsea He SM ’10

For many MIT students, the Bose Corporation is an audio equipment company whose speakers hang on their dorm room or apartment walls. In truth, the connection between Bose and MIT dates back more than 65 years.

In 1956, graduate student Amar Gopal Bose ’51, SM ’52, ScD ’56 purchased a stereo system. Disappointed with the stereo’s sound quality, Bose began researching acoustics and reverberant sound. He continued his research as an MIT professor and was awarded several patents on speaker technology. In 1964, he founded the Bose Corp.

As of April 2013, the company has eight operating plants and more than 150 stores worldwide.

“Most students don’t realize Bose is a company that began at MIT,” Lee Zamir ’95, SM ’97, Bose director of new business development, says. “We’re a startup in every way—innovation, making good devices even better, and producing new products.”

The Galactic Goats, most resilient team winners. Photo: Chelsea He SM '10

The Galactic Goats, most resilient team winners.
Photo: Chelsea He SM ’10

After Bose retired from MIT in 2001, the on-campus connection between Bose and the Institute diminished. Zamir wanted to change that.

In 2011, he connected with Associate Professor Olivier de Weck SM ’99, PhD ’01, whose fluid dynamics course features the annual Unified Engineering Flight Competition (UEFC), where student teams design miniature airplanes and control their movement around various obstacles.

Past UEFCs had never included a sound component. For the 2013 competition, under the guidance of Zamir and Bose engineers, the students  were required to fly their plane towards a beacon tower and chirp out M-I-T in Morse code. Another task involved jamming a target receiver with audio. Points were awarded for time and decibel level.

“The contest combined system design with flight precision,” Zamir says. “A plane’s speaker system needs to be lightweight and in the perfect spot. Otherwise it won’t fly.”

The competition was held in the Johnson Center and featured more than a dozen teams of four. The top three teams were recognized (“Supersonic ExitVelocity” took first place) as were the most resilient team and the most creative design.

Photo: Chelsea He SM '10

Photo: Chelsea He SM ’10

In addition to the UEFC, the students received a lecture on the elements of acoustic design. The competition also allowed Zamir and other Bose employees who are MIT alums the chance to return home.

“It’s great to get back on campus—especially to do innovation-based work,” he says. “We were looking to make the Bose and MIT connection even stronger and this was a perfect way to do it.”

While Amar Bose is best known as the company’s chairman, at MIT he was known as Dr. Bose, and a seat in his electrical engineering courses was highly coveted.

“When I was a student there in the early ’90s, there was always a fear that he could stop teaching at any time,” Zamir says, “We’d check the schedule, and when he saw his name, we’d register right away.”

In 2011, Bose donated a majority of the company’s non-voting shares to MIT (with a caveat that the shares never be sold) to help advance MIT’s research mission. Read the MIT News story.


Like any engineer who has sat in traffic, Gregor Hanuschak MBA ’08 has dreamt of ways to ease the car-commuter’s diurnal ordeal in major cities.

While earning his degree at Sloan, another master’s at Stanford, or in his work for Lockheed Martin and NASA in California and Washington, DC, Hanuschak has sat in plenty of traffic jams.

Even though studying traffic patterns and public transportation solutions are worthy pursuits, Hanuschak wants to relieve drivers’ stress with song—percussion, to be exact.

Smack Attack

The Smack Attack steering wheel drum set. Photo: Gregor Hanuschak.

Launched in April, Hanuschak’s Smack Attack project Reinventing the Wheel aims to do even more for drivers than just cure boredom. A “drum set for your steering wheel,” Smack Attack claims to be a remedy for zoned-out drivers.

The device is easy to use: wrap the flexible drum pad around your steering wheel, plug into your phone’s music library (or use a wireless FM transmitter) and start drumming along.

“Experiencing highway hypnosis firsthand while driving across the US inspired me to design something to fight it and keep drivers alert,” writes Hanuschak on his Kickstarter page. “Sleep researchers are finding the best way to fight highway hypnosis is through auditory or tactile stimulation… and this product provides both!”

The project has drawn the attention of the Discovery Channel, Wired, and dozens of other media outlets. Hanuschak has already raised more than $10,000 for the combination device/app concept.

Hanuschak will put his studies in music, computer engineering, and business to practice as he develops and markets the product this year. He has produced the code for the Smack Attack’s smartphone app, produced music and videos to promote the device, and created a community portal on his website for users to share drum sounds and songs.

“Right now I’m trying to bring my costs down,” Hanuschak said earlier this week, “so I’m now learning from the experts. I’m working with the MIT Venture Mentoring Service for advice on this and entrepreneurial advice in general.”


Update: View a video of this presentation.

Climate change policy can be complex, expensive to implement, and have unintended negative consequences on the environment. Focusing on the economics of transportation policy, Professor Christopher Knittel is working help create climate change policy that is more efficient and economically sustainable.

In the next Faculty Forum Online broadcast, Knittel will discuss his studies of consumer and company reactions to energy price fluctuations and the implications of this work for effective environmental policies.

Knittel, a William Barton Rogers Professor of Energy Economics and co-director of the Center for Energy and Environmental Policy Research, will introduce his research and take questions from the worldwide MIT community on Wednesday, April 10, from noon to 12:30 p.m. (EDT).

Register for this free eventClimate Change Policy that Makes Economic Sense—to receive the link for live viewing. After the event, return to Slice and continue the conversation in the comments.

Christopher Knittel

About Christopher Knittel

Before joining the MIT faculty in 2011, Knittel taught at Boston University from 1999-2002 and the University of California, Davis from 2003-2011. His research focuses on environmental economics, industrial organization, and applied econometrics.

He is a research associate at the National Bureau of Economic Research and an associate editor The American Economic Journal—Economic Policy, The Journal of Industrial Economics and Journal of Energy Markets. He received his bachelor’s degree in economics and political science from the California State University, Stanislaus in 1994, a master’s degree in economics from Davis in 1996, and a doctorate in economics from University of California, Berkeley in 1999.


Use Subsidies Elsewhere,” New York Times (editorial), October 7, 2010
The Economics of Energy,” MIT Spectrum, spring 2012
Christopher Knittel uncovers surprising facts about the cars we drive — and about the price of gas.” MIT Joint Program on the Science and Policy of Global Change
Faculty Profile: Christopher R. Knittel