13-23: Direct Drive Motor Design - Improving Product Availability byThe horsepower and speed required for a given fan depends on many factors, including maximum tip speed, blade design, blade pitch, and required CFM. There are an infinite number of HP RPM shaft combinations that could be requested from a direct drive motor manufacturer. With careful design, it is possible to create a "universal" motor that covers a wide range of requirements. This paper discusses characteristics that must be considered when designing