This may sound strange but the answer to your question may be answered by an explanation given to me by an accomplished 3D pilot. He explained that air is a fluid in motion and the more air flow the easier it becomes to control a model aircraft in flight. Think as air flow as wave motion. The bigger the wave the easier it becomes for a surfer to perform certain manuvers.
He went on to explain that you need constant wind felocity of at least 10mph to learn how to do this manuver. With the help of constant airflow it will be easier to maintain elevation and heading while in the learning mode.
It made a believer out of me when I whitness his words but into motion. I understand this may sound to simple but it is certainly a starting point.