Aircraft OML Reverse Engineering Enables Complex CFD Analysis

In 2009, Direct Dimensions Inc. was approached by Texas A&M University’s Flight Research Laboratory (FRL) with a challenging yet typical 3-D problem. The FRL, while primarily an active teaching facility, also offers both flight and wind tunnel test services. This particular project was for a customer who had contracted the FRL to perform feasibility and conceptual design studies for a flight-test program using a business-jet class aircraft.

This type of virtual aerodynamic testing, called CFD analysis, or computation fluid dynamics, requires a dimensionally accurate “as built” 3-D CAD model of this specific Gulfstream airplane. The FRL would also need additional 

3-D models showing the plane in various configurations, such as with and without the engine, and with and without the vortex generators.

Given the complexity of these specifications, the FRL contracted Direct Dimensions Inc. (DDI), a reverse engineering company based in Owing Mills, Maryland, with 15 years of expertise with 3-D metrology technologies, specifically within the aerospace industry. Their extensive experience in creating accurate 3-D models for CFD analysis made DDI uniquely suited to work on the team’s project.

Over the course of three days, DDI engineers worked on site at NASA’s Forward Operating Location in El Paso, Texas, to scan the entire outer mold line of the designated Gulfstream II. The airplane surfaces were captured using the uniquely accurate Surphaser 25HSX 3-D laser scanner. This scanner captured the shape to an accuracy of less than 0.25 mm with extremely high data resolution. The ease of use and portability of the Surphaser allowed the large plane to be scanned from multiple positions to rapidly obtain all the data for the final CAD modeling process.

With the raw point-cloud data gathered during scanning, DDI engineers then created reverse engineered 3-D CAD models using PolyWorks, Imageware, and SolidWorks software. These digital models allowed the FRL to then “virtually” test the aircraft and design modifications in their CFD program and evaluate the suitability of the Gulfstream II for the test program.

You can read more about the test program here.

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