Wind tunnel witch creates spooktacular Schlieren Published Oct. 31, 2022 By Bradley Hicks AEDC Public Affairs ARNOLD AIR FORCE BASE, Tenn. -- Arnold Engineering Development Complex Fellow and Volunteer Emeritus Dr. Bill Baker helped conjure a bewitching supersonic Schlieren of a model resembling a certain Halloween staple. In 1962, while a student at Mississippi State University, Baker made an aluminum model of a broomstick-riding witch in the school’s aerophysics shop. “I was working in the shop on another project and there was a scrap piece of aluminum, so I cut out the witch on a bandsaw just for fun,” he said. Although he originally fabricated the witch “as a lark,” Baker later decided to see if he could run it in the Mach 2 blowdown wind tunnel at MSU. Unfortunately, the 2.5-inch witch Baker made was too large to run in the 3-inch by 4-inch tunnel. Baker was finishing his master’s thesis and nearing graduation, so he lacked the time to construct a smaller version of the model. However, a fellow student loved Baker’s idea and took it upon himself to make a witch model suitably sized for the MSU tunnel. After this new model was run in the tunnel, Baker’s peer sent him a photo of the Schlieren. That photo is the image shown here. Baker earned his master’s in August 1963 and began his nearly 60-year AEDC career in August 1964. Baker retired in 2021. He was inducted as an AEDC Fellow in 2004.