To design a wind axial turbine, it's essential to calculate the required power using the formula Power = Torque x rpm x % Efficiency of the generator. Understanding the relationship between torque and rpm is crucial for meeting power requirements. The blade design must be optimized to generate sufficient torque at the desired rpm and wind velocity. Researching "propeller design" can provide insights, though it may not yield straightforward solutions. Proper calculations and design considerations are vital for effective turbine performance.