New airplane design

I've come up with what I think is a good, original design for an ultralight or ARV airplane, and I've reached the point where I'm considering actually building and flying a full scale airplane. I've built and flown many R/C models, 1/6, 1/4, and 1/3 scale, I've been to Osh Kosh for the past 20 years, etc. I'd like to post some pictures of it on this forum to get some reactions, advice, and suggestions, but I'm a little worried that someone might steal the design. I entered it in an EAA design contest, but that was a long time ago. What can I do to protect my design? Is an 'ornamental design' patent the way to go? How much time and money would that take? Or do you just put your design out there and 'wing' it? THANKS!