NASA's 16-Foot Transonic Tunnel Leaves Powerful Legacy NASA -- When the massive fan blades stop turning for the last time on September 30, 2004, the steel walls of the 16-Foot Transonic Tunnel will continue to reverberate with an incredible history of aeronautical research spanning over six decades.    The stone "NACA" plate over the building's main entrance at NASA's Langley Research Center only hints at the historical significance of the facility...