I had the same problem with my Nobler. Our field is grass and it can get a little rough. It was almost impossible to taxi without nosing over a little and breaking the prop. I tried a 10 1/2 inch prop and still had problems. I ended up getting a "mighty bender" and some piano wire, and made some new gear wires that are slightly longer and bent a little forward. This setup works great. I'm still flying with the original 11x5 APC prop that I mounted three months ago!