Aerodynamics Experimental Facility Upgrade: Downrange Distance Measurements

Author(s):

Joseph Haire and Ilmars Celmins

Abstract:

The Aerodynamics Experimental Facility (AEF) is a spark shadowgraph range located at Aberdeen Proving Ground, Maryland, used to determine aerodynamic coefficients of projectiles in free flight. To accurately extract the coefficients, precise knowledge of the projectile’s 6-degrees of freedom coordinates as it travels downrange is required. These coordinates are obtained by taking orthogonal photos of the projectile in free flight at numerous stations along the length of the range. A fiducial notch is located at each range station and is used as a reference for the projectile position in each photo. At the time of publication, the AEF range is undergoing an upgrade from analog to digital hardware. After the installation of the new hardware, the downrange position of the fiducial notches must be surveyed to provide position inputs for the aero data reduction software. This report discusses the procedure used to determine the downrange location (Z direction) of each station’s fiducial notch relative to the first station’s notch. The notch locations were measurable with an uncertainty of less than 0.04 inch (1 mm).