NASA aerospace engineers Pete Zell (left) and Dr. William Clifton Horne (right), project director are shown preparing a laser light sheet for a flow visualization test. The subject of their test is Pratt & Whitney's Advance Ducted Propulsor (ADP) demonstrator engine in the Full-Scale Aerodynamic Complex (NFAC) 40 x 80 foot Wind Tunnel. Shown standing in the nacelle of the ADP is John Girvin, senior test director at NASA Ames Research Center.