Jason,

I have flown 1/2A engines with 5% and 10% nitro fuel. The 5% is a little harder to start. Standard Cox 1/2A fuel had 15% nitro, their Racing fuel had 25%. Try some different blends and see what works for you.

My Brodak Basic Trainer does not loop. I have it set-up with minimum control for kids to learn on. If you set it up with more control and balance a little further back so it is a bit more sensitive it may loop, but then it will be harder to learn on. Don't expect a lot of performance, the plane has a high wing loading. Give it a try.

Also remember that the Sure Start engine has about twice the power of my old Cub .049A, so you can fly it on longer lines.

George