NASA has recently selected Term-LAB to measure the Sound Pressure Level generated by the Space Shuttle during liftoff. According to NASA engineers, acoustical measurements during liftoff have not been attempted for more than a decade. And, even then, reliable measurements were difficult if not impossible to achieve due to the extreme nature of the SPL being produced. After researching the available test equipment on the market, Term-LAB was selected for this very demanding application.
NASA plans to use the measurements recorded by Term-LAB to identify specific frequencies that could be causing damage to the pad during launches. The need for logged data required some significant additions and enhancements to the Term-LAB software. Wayne Harris, president of WHE Inc., worked closely with NASA engineers to develop these changes.
The first measurements were taken during the launch of Discovery on May 31, 2008. The sensor was attached to a high-speed camera mount located 1300 feet from the launch pad. The Term-LAB system was switched to “NASA Mode” and the data logger began logging measurements to the computer’s hard drive several minutes prior to liftoff.
The logged data was then reviewed by NASA and WHE Inc. Based on this data, the shuttle established a peak “dB Drag” SPL of 147.7 dB at 20 Hz. While a score like this won’t set any dB Drag Racing World Records, it is very impressive when you consider that the measurement was taken from 1300 feet away and that the frequency where the maximum SPL occurred was 20 Hz.