Cadet research is helping NASA shuttles return to space

The shuttle program has been land-locked since the Feb. 1, 2003, loss of the Space Shuttle Columbia. This academic year, the Air Force Academy is assisting NASA’s Return to Flight program by utilizing the skills of instructors and cadets, and putting a model of the space shuttle through its paces in the wind tunnels of the Department of Aeronautics.

“Mainly we’re looking at its stability characteristics — both longitudinal and lateral-directional — and aerodynamic characteristics such as lift, drag, and lift-to-drag ratio, which is a big indicator of glide range,” said Cadet 1st Class David Schmitt.

That research includes the impact of leading edge damage on the shuttle’s wings, added Cadet 2nd Class Matt Karmondy. “The objective was to see if leading edge damage would adversely affect, lift, drag, and stability of the shuttle after reentry. It turned out certain damage configurations did raise some concern, and further investigation will be conducted to see if the shuttle has the capability to overcome stability issues caused by wing leading edge damage.”

The research is being accomplished in the Academy’s Aeronautics Research Center. This 5,100 square meter facility houses world-class experimental and computational facilities, including five wind tunnels. NASA provided a 1.67 percent scale aluminum polymer model of the shuttle, for use in the Academy’s subsonic wind tunnel. This tunnel simulates speeds of 50 to 600 feet per second.

Last semester’s research started with a baseline evaluation of the shuttle model. Once the baseline data was collected, several different leading edges were fitted on to the model. These changes simulate damage at different locations, allowing researchers to evaluate the resulting changes in pitch, roll, yaw, stabilization and other aerodynamic characteristics of a damaged shuttle.

This semester’s efforts expand the research into the wing structure itself, said Dr. Thomas Yechout, Aeronautics department professor and research advisor for the project.

“NASA is in the process of having a new wing for our model fabricated,” said Yechout. “It will also have a variety of damage configurations along the left wing. It differs from the first model wing since it will include a cavity inside the wings’ leading edge, with pressure taps inside the cavity at various locations to measure pressure loads in the vicinity of the damaged structure changes.”

According to The Columbia Accident Investigation Board, the loss of the space shuttle was caused by a piece of insulating foam which separated from the external tank at 81.7 seconds after launch, and struck the left wing’s leading edge. Upon re-entry, this breach allowed superheated air to penetrate the leading edge insulation and progressively melt the aluminum structure of the wing. This weakened the wing until the increasing aerodynamic forces of reentry caused loss of control and failure of the wing. The Columbia broke up at an altitude of 203,000 feet while traveling at Mach 18, just 15 minutes prior to its scheduled landing at Kennedy Space Center, Fla., killing all on board.

NASA is utilizing the research capabilities of several organizations as part of its Return to Flight program, including the Air Force Academy’s Department of Aeronautics. The Academy’s been involved with NASA research for the past 8 years, dealing with several past, current and future spacecraft.

The Return to Flight research is one of approximately 300 undergraduate research projects currently underway at the Air Force Academy.