Specialized CAD tool cuts hours from airplane development
If you’ve ever tried to model an airplane in traditional CAD tools, you know it can be challenging at best. Short of pain stakingly lofting surface cross-sections, the fuselage typically looks more like a cylinder, the boxy wings have flattened tips and putting the taper and twist on a propeller blade can make you want to stab your monitor to death.
For the conceptual aircraft designer, NASA has come to the rescue. At the recent American Institute for Aeronautics and Astronautics (AIAA) Aerospace Sciences Meeting, NASA officially releasing its internally developed parametric aircraft modeling application — OpenVSP (short for Vehicle Sketch Pad) — under the NASA open source license. The intent of the application is to assist in the quick development of conceptual aircraft design, particularly by those unfamiliar with traditional CAD.
For example, contrary to general purpose CAD applications, OpenVSP includes a library of standard components or primitive geometric building blocks common to all aircraft, including fuselage, wing and propeller, among others. Modeling typically begins by importing a .jpg file of a target plane’s top and side views.
A fuselage object is then created and its cross-sections fitted to the image’s outline. Then a wing object’s parameters – including span, sweep, root and tip chord, etc – are manipulated through a series of sliders or direct numeric input to fit the aircraft’s profile. Control surfaces, engines, propellers, landing gear, struts, etc can be similarly modeled.
Once the model is finished, a mesh can be generated and wetted area of the plane calculated. In addition, meshes for further FEA or CFD analysis can be generated and exported or the model itself can be output for further detail work in traditional CAD packages.
Currently, the application can import STL files and outputs basic point data (Xsec file), computational fluid dynamics (CFD) geometry (Felisa and NASCART), solid modeling (STL), Rhino 3D (.3dm), or several standardized geometry formats (Techplot, Stechplot, and POVRAY). It also outputs Nastran geometry and Calulix, an open source FEA application.
OpenVSP is available as native executables for Windows and OSX, but sources code can also be compiled for Linux operating systems. Although unsupported by NASA or any software vendor, the application has a dedicated training site and user manual.