Dropping stuff for science

A unique new structure in the Engineering Building enables students and faculty to learn more about what happens in space. The Dryden Drop Tower is 102 feet high, which gives researchers 72 feet of free-fall in which to observe weightlessness.

The two second time span is long enough to observe how fluids react in a low gravity environment. The tower, located in the Engineering Building’s atrium, reaches from the fifth floor to the basement. The open enclosure allows people to view the drop from any floor.

The inaugural drop occurred on June 16 at a party held for donors and friends of the former dean of the Maseeh College of Engineering and Computer Science, Robert Dryden. The tower is named after Dryden, who served as dean for 13 years.

According to the DDT website, the project was headed by the DDT Board, composed of Yongkang Chen, a mechanical and materials engineering research associate, Trevor Snyder of Xerox and Mark Weislogel, a mechanical and materials engineering professor.

Drop towers are used to learn how fluids and other materials behave in low gravity. According to the DDT website, the fixture is similar to the 2.2 second drop tower operated by NASA in Cleveland, Ohio. The DDT is unique because it is located in a public space, available for viewing by anyone in the building.

According to Weislogel, the materials that are to be studied are loaded into the payload center. A drag shield surrounds the chamber to remove drag caused by the air the chamber falls through. High-speed video cameras inside the chamber enable researchers to see what happens to the materials being tested.

The DDT will primarily be used to study capillary action and fluid dynamics. In low gravity environments—like in space—fluid behaves very differently. Designing fuel containers, cooling systems and life support systems in low gravity environments is important for space missions, Weislogel said.

Capillary action refers to how liquid behaves. This behavior changes depending on the forces at work on it.

“When gravity is gone, smaller forces that are always there start dominating and it looks weird,” Weislogel said. Fluid can be forced to move in a very different way in a weightless environment, depending on the geometry of the object containing it.

Weislogel is collaborating with a team in Germany on experiments that will be performed at the International Space Station sometime this year.

“The drop tower has been essential for our experiments,” he said. “It also proves our tests so we’re guaranteed the experiments in the space station will work.”

Renjeng Su, dean of MCECS, said, “We expect that the Dryden Drop Tower will attract students of all ages, faculty from many institutions, and industrial scientists and engineers. We will welcome them to conduct experiments with the Tower.”

The DDT cost over $300,000 and was paid for by donations, including design donations, Su said.

“It is a project that has generated enthusiasm and support from friends of the Maseeh College as well as a wide engineering and architecture community in Portland,” he said.

According to Weislogel, the project provided the opportunity to honor Dryden and to reach out to K–12 students. As long as nothing breaks, he said that the structure takes little money to maintain.

Learn more about the drop tower and opportunities to get involved at www.ddt.pdx.edu or e-mail Mark Weislogel at [email protected].