IV Manufacture and Flight
The main structures of most small fixed-wing unmanned air vehicles (UAVs) are essentially built using fiber-reinforced plastics of some kind with the addition of foam, plywood, and metallic parts where needed. To these are assembled a whole raft of externally sourced components, which are then connected via suitable wiring harnesses. As has already been made clear in Parts II and III of this book, we have adopted the use of 3D printing (rapid prototyping) to deal with a great deal of the more complicated geometries needed in our UAVs and have limited the use of fiber-reinforced material to stock shapes that can be bought in and used with little further effort, though they still usually form the main load-bearing backbones of most of our airframes (see Table 18.1 for typical properties). We thus avoid the use of molds with glass-/carbon-fiber-reinforced plastic (GFRP/CFRP) lay-up processes completely; molds are expensive and add a layer of tooling that we no longer believe necessary, though many commercial UAVs are still produced in this way and we often manually clad our foam parts in fiber materials.