This image or file is a work of a
U.S. Air Force Airman or employee, taken or made as part of that person's official duties. As a
work of the
U.S. federal government, the image or file is in the public domain in the United States.
An engineer using a
w:slide rule, probably in 1950s. Note calculator in background. Source: Aeronautical Systems Center (ASC) History Office http://www.ascho.wpafb.af.mil/Genesis/chap2.htm
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