You can zoom in and out, rotate or pan the models available here. Visualization services provided here helps you to understand Complex engineering drawings. Autocad R13 drawings are listed here. Good listing of 35 drawings showing manholes, typical sewer pipe installation in trench and so on. Worth taking a look Aircraft Models Aircraft models are available for download from this site.
All files are in .dxf format and have been compressed as .zip files.
CAD Download Page CAD Download Page. Click on the file. Your browser will ask you where to save the file. Save the file in a directory, double click on the file and it will automatically expand into a .dwg file. The 3D files are highly simplified to reduce disk overhead on your system.