Designing a plane to fly 10 times the speed of sound

To Ted Conbeer ’08, the task assigned to his engineering class seemed “a little like science fiction.” The project? To design a hypersonic aircraft that could carry 10 passengers and two crew members from Tokyo to New York in less than three hours and for less than $100,000 a ticket.

Conbeer’s assignment was part of a junior-level design course, “Aircraft Design,” required of all mechanical and aerospace engineering students. Luigi Martinelli, an associate professor who normally teaches the class, said the course is a culmination of students’ coursework in the department and an introduction to real-life problem solving.

“It’s the first time they are making connections between mathematics, physics, and application computing,” Martinelli said. “They’re bringing everything together, and they have to start integrating all their knowledge.”

In the past, the students in the class have focused on more conventional vehicles, such as seaplanes or business jets. But during the spring semester, the juniors and seniors applied their engineering know-how to designing a hypersonic airplane capable of flying more than 10 times the speed of sound. Leading the class this year was Kevin Bowcutt, chief scientist of hypersonics and a senior technical fellow at Boeing.

Working in three teams of about 10 students each, Bowcutt’s class designed three types of hypersonic airplanes: a one-stage cruiser, which would stay within the atmosphere and be propelled by its own power; a two-stage cruiser, which would also stay within the atmosphere but be propelled by a separate, larger aircraft; and an exo-atmospheric cruiser, which would be self-propelled and enter suborbital flight during its voyage.

The teams generated 3-D computer models of their designs, and the winner was picked by a panel of judges that included a NASA researcher, a professor in the Johns Hopkins Applied Physics Laboratory, and a colleague of Bowcutt’s at Boeing. “It was a very broad and extensive look at all the different aspects you are required to look at for the design of hypersonic vehicles,” said David Glass, a senior research engineer at NASA. “They did a good job.”

Bowcutt said the students developed a novel way of designing the passenger cabin and fuel storage of the plane so that the vehicle’s center of gravity would remain fixed during flight. The group working on the exo-atmospheric cruiser also came up with a new wing design that integrated the plane’s propulsion system and allowed for a varying wing area.

“Anything I learn here, any good ideas, I can bring them back to Boeing,” Bowcutt said. “We will look for opportunities to leverage this.” He said he has encouraged his students to submit their design to a competition organized by the American Institute of Aeronautics and Astronautics.

Having Bowcutt as a teacher had its perks, students said.

Alex Van Hoek ’08 said the class offered him the chance to work with people in the industry who could give him guidance and feedback. Caroline Teichner ’07 also enjoyed the connection with the aeronautics industry: “It was the only class that made me feel like I was doing something that might relate to the real world.”

Bowcutt hopes his time at Princeton will inspire future engineers to continue the hypersonic aircraft-design work on which he has focused for 25 years.

Although he estimates that hypersonic flight is 10 to 20 years away, he hopes to see it become a reality. “This is my dream — I want to do this,” he said.