Often, as I have found anyway, our control and the way we handle the transmitter has a lot to do with the attitude of the plane as you enter a maneuver, such as a loop. It takes practice to add elevator without ANY aileron influence. Practice and focus. Try to do a loop and focus on your straight back pulling of the elevator. If the plane is set up properly, your and your input is straight back, the plane will do a nice round loop without any roll. And of course, it helps to start out by flying directly into the wind.

As I said, practice and focus works every time. And as my 'instructor/mentor' always tells me, burn fuel. Period. Burn fuel and practice practice practice.

CGr.