This 1949 photograph shows a Douglas D-558-2 undergoing pre-flight operations on Rogers Dry Lakebed at Edwards Air Force Base. Note the small inlet on the left side used for the turbo-jet engine in this aircraft’s propulsion system. An often overlooked aspect of flight research is the large amount of pre- and post-flight maintenance and fabrication work it requires. Before a flight, the aircraft's systems had to be checked out, the instrumentation calibrated, cameras and oscillographs loaded with film, and the aircraft serviced with propellants. After a landing, the data had to be ''reduced,'' by human ''computers'' in the case of the early X-planes including the D-558s, which would have been X-planes had they been sponsored by the Air Force instead of the Navy. The ''computers'' ''read'' the films and converted their markings into data on sheets or in graphs that research engineers could then use in their analyses.