Evaluation of a 10-Foot Diameter X-Wing Rotor

A 10-ft diameter, Mach-scaled model of a potential full-scale demonstrator aircraft was built and tested to obtain data at tip speed and disk loadings considered to be representative of those required for an operational X-Wing aircraft. A higher harmonic control capability was considered necessary and was a primary factor in the model design. The test program covered most flight regimes including hover, transition, forward flight to conversion speeds, and high advance ratios representing conversion. The paper presents a brief discussion of the circulation control concept, a description of the model, and a discussion of the major aerodynamic test results. Hover shaft power data is presented and compared with the results from a previous model. The low speed transitional flight regime is discussed, and data demonstrating the trim requirement and critical air-speed is presented. A simple algorithm for applying higher harmonic control is included that resulted in flapwise bending moment reductions of nearly eighty percent. Finally, a comparison between test data and analytical predictions is made, and generally good agreement demonstrated.