New & Improved Trubines

So...after working and researching the different types of turbines which have been developed, I decided to investigate the Helical turbine. The main advantage of this type of turbine, is that it is derived from both the Savonius and Derrieus turbine...and hence, it has the best of both worlds in the sense that it has drag and lift capabilities.
After several attempts of developing one, I finally managed to build a few myself. The craftmanship of the turbines are far from exquisite, but the efficiency is still there. I found that these were much lighter in weight as well as easier to rotate and generate movement. One thing which I noticed but was not at all surprised with, was the aspect that the wider the aerofoils were, the less efficient my turbines were, due to there being more surface drag. So the question now becomes, how small of an aerofoil do I have to develop so I reach an optimal relationship between lift and drag.