Advanced modeling tools and concepts are essential to allowing an engine/drive system to achieve a significantly larger speed range without sacrificing power and efficiency. These tools and concepts include high-efficiency, multi/variable-speed drive systems, oil-free engine/optimized gearbox systems, and wide-operability engine systems for rotary wing applications.

Rotorcraft propulsion is a critical element of the overall aircraft. Unlike fixed wing aircraft, the rotor/propulsion system is used for aircraft lift, forward flight, and maneuvering. As a result, the rotorcraft engine/gearbox system must be highly reliable and efficient. Future rotorcraft will be more versatile, efficient, and powerful aircraft that challenge state-of-the-art propulsion system technologies. Advanced tools and methodologies must be developed that enable industry to more accurately and effectively develop and design new engine and drive system technologies. The overall approach for meeting future rotorcraft propulsion challenges is to focus on the following key research areas: variable/multi-speed drive system technologies; improved drive system analytical tools; optimized gearbox/engine system; oil-free engine technology; wide-operability engine technology; and efficient, high-power-density engine technology.