Scanning a 50-Year-Old Swedish Draken Fighter

Abstract

When a large aerospace and defense contractor wanted to research the aerodynamics of a 50-year-old Swedish-built jet fighter, the Saab Draken, it turned to Exact Metrology of Algonquin, Illinois, for its unique capabilities to speedily process point-cloud data using Polyworks software from InnovMetric Software Inc. The contractor wanted a very accurate data map of the aircraft that could be imported into engineering analysis tools to obtain real aerodynamic performance. The data were needed to ensure that an airframe structure under development by the contractor could survive in 21st century combat environments. The mission was given to Exact Metrology, a digitizing and surveying firm. Their task was to generate complete, accurate surface data of the entire aircraft plus high-resolution scans of weapons and gun bays, which could be fed into the contractor’s computer simulations. The scanning was done at a private airport 26 The Journal of the CMSC/Spring 2008 and aircraft graveyard at Inyokern in California’s Mojave Desert. Six of the remaining Drakens (Swedish for “dragon”) are stored, refurbished, and flown there. The technical challenge was creating aerodynamic surface data files by merging high-definition and low-definition scans. The differences in resolution were enormous. Points in 3-D space in the high-definition scans were about 1 micron apart and points in the low-definition scans were about 1 millimeter apart. That meant that the high-definition scans were 1,000 tim