The low rpms is the killer and the fact that the vawts tend to not take advantage of higher winds cause they seem to be self limiting. I think that may be caused by the cylinder shape so they start to flow the air around them when the turbulence caused by the blades gets very high especially in the stronger winds. The turbine starts to act like an airfoil and some of the energy of the wind is diverted to create a force at 90 degrees to the oncoming wind. The side which spins in the same direction as the wind is the bottom of the air foil and the side which spins into the wind is the top of the air foil. Magus effect.

Hey you never know what will happen till you try. I think it looks great. My barrel vawts are a big success but only as yard art. I have 3 orders to fill by Xmas. No energy made just spinning eye candy.

Have fun learning