The air coming out of the leaf blower is probably going to be wayyyy too turbulent to get meaningful results from. You could always spritz water on the model and see which way it gets blown off but I don't know of any better way to test it. Neil Blanchard put together like five leaf blowers to test his 1/4 scale (?) foam model, but even 1/18 is very small.
Now if you have a 1/4 scale car model lying around, lets' talk!
