Champaign-Urbana Community Fab Lab

Betty Barrett writes:

Dave Semeraro is a member of the CUCFL community and joins us on a regular basis to work on projects in the lab. During the time he isn’t in the lab, he hangs out at the NCSA where he helps people create visualizations of large scale models of physical processes. His undergrad and master degrees are in aeronautical engineering and his PhD is in computer science. His early passion for aeronautics shows in the work he is doing in the lab.

Recently he brought in the completed model he built of a Sopwith Scout that pilots called a Sopwith Pup. It is a WWI single seat fighter plane that he has crafted out of lightweight balsa wood and tissue paper. The model weighs about 40 grams. Dave says that he was able to achieve such precision and light weight due to the laser cutter that allowed him to cut out small internal pieces to reduce weight. On the tissue paper he applied aircraft dope to give it some strength. Another modification he made was to glue 20 thousandths carbon fiber rods to the wood of the landing gear to give them strength. Markings on the plane were designed in Inkscape and printed on decal paper.

Dave says that in the lab he could refine his technique to create models that were lighter than normal. He could also design the structure so that the parts fit together in a tab and slot sort of way. This is called self jigging, where you don’t need a lot of external fixtures to keep things square and aligned. The structure does it itself. You can design this in with CAD software and align everything very precisely so that everything slots together and fits. The precision of the laser cutter and the CAD software really helps with this.

Dave estimates that the model took six weeks to build the model from the scratch drawing to having the structure done. It took a several more weeks to get the radial gear in and test fly the model. Next he plans to build a bigger model that will have ailerons with slightly bigger servo motors. It is also a WWI plane, a British observation plane - a BE2C.