Investigation of Cross Flow Fan Propulsion for Lightweight VTOL Aircraft
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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As world population increases, road and airport congestion will become increasingly prevalent. A small, cheap VTOL aircraft that can be flown from a driveway to the workplace parking lot would reduce traffic congestion and travel time. A lightweight, single seat commuter type VTOL aircraft is envisioned as the solution to this problem. To achieve a goal of minimum weight, the aircraft aerodynamic design should be optimized for forward flight. Vertical thrust augmentation from a propulsion unit contained within the fuselage would have little detriment to forward flight aerodynamics, and the cross flow fan can be accommodated as such. Cross flow fan propulsion has not been seriously considered for aircraft use since an LTV Vought Systems Division study for the U.S. Navy in 1975. Despite an indepth knowledge of the design parameters and airflow relationships in cross flow fans, the existing data support the hypothesis that with further development the thrust efficiency and thrust to-weight ratio could improve to the point where this thrust producing method is viable. This study investigates the incorporation of rotary engine powered cross flow fan propulsion in a hypothetical lightweight VTOL aircraft and concludes that cross flow fan propulsion is viable, but only with further investigation of power plant technology and fan design parameters and relationships.