Hi wzak29
I'm glad you asked. It stands for Simple Plastic Airplane Design. It involves building model airplanes from a corrugated plastic material (like a cardboard box except it is plastic). This material is what sign companies use to make political and other signs. If you scroll down to the SPAD forum and look in the author column for villa, you will see photos of some of the planes I built. Free plans are available at spadtothebone.com. The website devoted to the SPAD plane is spadworld.net. It is a way to Fly R/C at a very low cost.