According to Azhar, the prototype flew fine with the CG right on the wing tube. In mine, the batteries are well forward but still behind the firewall. It balanced perfectly on the wing tube with spinner but no prop. Once the prop is in place it should be about right for the maiden. If an engine that is much lighter than the DLE30 is to be used, keep the tail as light as possible. Using a single elevator servo would help a lot, as this airplane has a long tail moment. Having gotten this far I now believe that a 50cc engine is doable assuming the structure is reinforced accordingly. At that point the wings would probably be the limiting factor, along with the wing tube itself. I'll leave that experiment to some other brave young scientist. I think it will be lots of fun with 30cc-class power, so I'll stick with it the way it is.