One of the unanticipated benefits of converting my botched first attemt at a cowl into a mold for the real cowl was an improved ability to visualize improvements in the cowl and make modifications to the mold to accomplish those improvements. When I made the plug mold by enclosing the engine in hardware cloth, duct tape and fairing compound, I made it too tight in some places and excessively large in other places. One example is the space around the carbeurator, air filter and alternate air assembly. I found it hard to visualize exactly how much space I needed there, so I made the plug mold bigger than it needed to be in that area. Now that I have the mold to help me see exactly how much excess space there is in that area, I can make plans to fill that space with spray foam and make that part of the cowl more streamlined in that area. In image 3 below, the black line represents an area that can be filled with foam, and glassed over with another layer of fiberglass, to make a more streamlined shape for my eventual cowl. This is working out well.
