As we begin to expand our exhibitions about Enterprise, we contacted NASA Langley to see if it would be possible to receive some relevant objects on loan. The extremely helpful and generous staff there recently lent us some wind tunnel models on our wish list. Some of these wind tunnel models, as well as Enterprise herself, were used in the investigation after the Columbia Disaster
Wind Tunnel with Model. Courtesy of NASA.
Wind tunnel models are scale test models used to anticipate how a full scale version of a vehicle will react in a particular aerodynamic environment. The friction from the hypersonic wind simulates the heat experienced by a shuttle upon reentering the Earth’s atmosphere. Contained in and around the wind tunnel are sensors and other equipment that help researchers monitor the results of the test.
L2012.10.02.04. Mach 6 Wind Tunnel Model. On Loan Courtesy of NASA Langley.
In the wake of the 2003 Columbia Disaster, NASA scientists created over 70 wind tunnel models to test the effects of heat on shuttles. One theory was that foam had struck the left wing causing fatal damage. By placing the model in a wind tunnel, NASA researchers could see how a damaged shuttle would react under reentry conditions and ultimately pin point the reason why Columbia broke up.
An example of the tests run on the Mach 6 Wind Tunnel Models. One can see the different heat patterns depending on the modification to the model. These wind tunnel tests focused on modifying a panel on the left leading edge. Courtesy of NASA.
The models are coated with a special chemical layer that fluoresces under UV light. The warmer the model is, the more fluorescence it produces. Engineers developed a program specifically for these experiments called the Shuttle Image Management System (SIMS). The SIMS allowed researchers to know the temperature at different points and see the effects of the modified wind flow on the model. After running these small scale tests and ruling out the least likely scenarios, NASA staff conducted large scale tests on Enterprise herself. In fact, NASA installed heat shield tiles on Enterprise for these tests. When you visit, you can see the scarring on the leading edge of the left wing and on the left main landing gear door from these tests.
The Shuttle Image Management System (SIMS) that NASA staff created also had a practical application for the real space shuttles. It permitted astronauts in space and engineers on the ground to view the temperature of the shuttle throughout the mission so that any damage in the thermal protection system could be reviewed and fixed while in space. The direct effect of this program was evident on Discovery’s mission STS-114, the first flight after Columbia. Based on analysis from SIMS, Astronaut Stephen Robinson replaced two gap fillers in between thermal tiles which had become exposed during lift off. If the fillers were not replaced, a dangerous amount of heat could have presented problems for the shuttle upon reentry. Not only was this the first external shuttle repair made during orbit, it was also the first EVA (extravehicular activity) underneath a shuttle.
Be sure to look for the wind tunnel models and other artifacts on display as we supplement our Enterprise related exhibitions throughout the coming year!