Fan inlet for a V/STOL airplane

An inlet was designed for a tilt nacelle lift/cruise fan. A complete set of low speed data was obtained with a 38-cm diameter cold-flow model, and a partial set of data was obtained with a 140-cm-diameter inlet coupled to a high bypass turbofan. The results indicate that a fixed-geometry inlet is a viable concept for the proposed application. Analyses of the data demonstrate that at high angles of incidence and at low airflow rates inlet-flow separation is strongly sensitive to Reynolds number and, consequently, the large-scale inlet has a significantly greater range of separation-free operation.