Saturday, July 12, 2008
Tech students win NASA design competition
The six undergraduates designed a commercial airplane of the future.
Shaozhuo Cui | The Roanoke Times
Bakar Bey, a senior aerospace engineering student at Virginia Tech, talks to teammate Stephen Pace, who just graduated from Tech, and his professor, Andy Ko, about what he said were the exciting moments he had when working on the STINGRAE project. Bey, Pace and four other students designed a commercial airplane of the future for NASA's Fundamental Aeronautics Student Competition and won the undergraduate division of the 16-team competition.
Courtesy of Stephen Pace
The airplane of the future
Some of the features of the STINGRAE- Digital throttling: The plane has four small engines rather than the two large engines used by today’s planes. Airplane engines run at peak efficiency at full throttle. But that power is used only during takeoff. For most of the flight the two engines in today’s planes are not operating at peak efficiency. By having four smaller engines, the STINGRAE can shut off two when it reaches cruising altitude and operate the other two engines at near full throttle, and peak efficiency, for most of the flight.
- Integrated geometry: The body, wing and engines of the plane are integrated into a single, "flying wing" design rather than the "tube and wing" used today. The design allows for more lift and less drag with the four engines located inside the plane. When two of the engines shut down they don’t create a "windmill" effect that would create drag if they were outside the plane. The flying wing design does present challenges of stability and control.
- Upper surface blowing: Allows the plane to generate additional lift from flaps and engines that accelerate air over the upper surface of the wing.
- Synergistic wingtip turbines: The condensation trails you see behind planes are caused by air wrapping around the wingtips, areas of very low air pressure as the wing generates lift. The wingtip turbines capture some of this energy and use it to power some of the auxiliary needs of the plane such as electricity and maintaining cabin pressure.
BLACKSBURG -- What will airplanes be like 50 years from now?
Will they be able to hop continents in minutes? Will they have hovercraft technology?
Maybe they'll be able to dive underwater. Or leave the Earth's atmosphere.
Maybe. But that's not what concerned a group of Virginia Tech aerospace engineering students when they designed the commercial airplane of the future for NASA's Fundamental Aeronautics Student Competition.
It's not what concerned NASA, either, as Tech's STINGRAE won the undergraduate division of the 16-team competition. NASA made the announcement Monday, and three of the six Tech students will travel to Atlanta for a NASA convention in October.
The competition asked students to address pragmatic issues such as noise, pollution, fuel efficiency and takeoff and landing distance.
The students -- Bakar Bey, Mike Fifer, Jon Frankenfield, Mike Lurie, Stephen Pace and Cabin Samuels -- entered the competition for their yearlong project for a senior aircraft design course. Andy Ko, an adjunct professor and aircraft design engineer with Avid LLC, a Yorktown company with research facilities in the Virginia Tech Corporate Research Center, taught the course.
STINGRAE stands for Short Takeoff Integrated Nacelle-less Geometry for Reduction of Acoustics and Emissions.
The plane, designed to be the next generation of the DC-3, does not look radically different from today's aircraft.
The students based their design on current research technologies that have been proven to work.
"Part of our design philosophy was to be radically simple," Pace said. "There's no radical change here or unrealistic technology."
The STINGRAE is designed to carry about 150 passengers and would be able to take off and land on a runway of only 3,000 feet. It would be the equivalent of having a 737 that is able to land at the Virginia Tech/Montgomery Executive Airport, Ko said.
The team worked 18-hour weeks for the entire academic year, researching technologies, running programs to predict the results of design changes and compromising on differences within the group. Its members turned in a 25-page report to NASA and a 100-page report to Ko. Pace said it was difficult at times to balance the demands of the project with other requirements of the class, such as midterms.
"This thing's due to NASA in two months," he remembers pleading with Ko. "We don't have time."
Pace said the concept that set up the design for the plane was "digital throttling." It's a technology used in the automobile industry. The new Hemi V8 engine, for instance, uses all eight cylinders when needed for acceleration. When cruising, it shuts off four.
The STINGRAE would be equipped with four small engines rather than two large ones, allowing it to shut down two of the engines when it reaches cruising altitude and making for a plane that's about 30 percent more efficient. The plane body was then designed to allow that concept to work.
Ko said he was impressed with the focus and restraint the students used throughout the design process.
"They didn't take every technology that's out there and try to lump it in and say, 'Let's just build this hodgepodge of things.' They really did a good job of trying to identify what makes sense," he said.
Another example of the students' pragmatism was the choice of fuel. They explored the possibility of fueling the plane with hydrogen. But problems such as the lack of density of the fuel would make it impossible for the plane to carry enough hydrogen for anything more than a short flight.
To allow the STINGRAE to have more range, the students chose Fischer-Tropsch synthetic fuel. Similar to jet fuel, it can be produced from biomass or coal. So although it's not a clean fuel like hydrogen, it's more practical and would not depend on foreign oil.
Bey, a senior, and Pace, now a graduate student at Tech, both want to work in aircraft design. For Bey, the competition experience just reinforced that desire.
"Bringing the concept together is what really gets me excited," he said. "That's what kept me going a lot as I was doing this project."
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