if you have drawn up plans, you can seal them in an envelope, and send them to your self as a certified letter. With a goverment agency certifying the date, I.E., the post mark, its a way to prove that you invented the device in question. They call it a Poor man's pattent. its not a great substitute for a patent, but its good protection while you're working on finalizing the plans.

I have an ex girlfriend who had been through the pattent process several times. her thoughts were that she should file for a pattent before ever mentioning she even had an idea to anyone. the risk is that someone else, hearing your idea will run out and patent it, then wait untill you have spent your time developing it and then demand you pay them before you can use it.

As for the plane, I plan to build it at 1/8th scale, which is a 40 inch wingspan. I'm intrested how the props workout on your slowstick. Its my understanding that there is some turbulance as the blades pass each other, so slow rpm, high pitch is better than high rpm, low pitch, but thats as far as I got in trying to design my plane.